A compact multi - function design of the inverter

discrete inverter challengeThe DC from discrete inverters
the solar battery module or another power source, it will be necessary to convert DC to AC. Applications in the user's changing power requirements, designers must be able to press additional inverters in parallel, or must the product is suitable for three-phase work environment. In addition, they need to efficiently and effectively provide such power. The inverter which requires flexible design can easily adapt to any future needs.
In addition, in view of the nature of the applications, these inverters must be compact and easy to carry. For example, remote campsites, boat, and the need for emergency standby power usually has no place of power grid, need to use the power in these circumstances. Meanwhile, these types of inverter must be simple to use and can be performed on-site maintenance,power inverter.

solutions
The inverter only
customers weighing 8 kg, acceptable nominal battery voltage of 24V or 48V nominal output 2200 VA, efficiency up to 93%. These discrete inverter charging technology and inverter integrated. In order to achieve compact size and easy to carry, customers with a high-frequency transformer-based inverter architecture, the architecture consists of the input level of high-frequency power, high-frequency transformer, intermediate DC link and the output power level. As a result, the discrete inverter simply relying on small high-frequency transformer, rather like other similar design as a large low frequency heavy-duty transformers.
by applying the concept of the high-frequency, connected to the load of the inverter, is almost directly connected to the output stage, thereby eliminating the attenuation problems commonly faced when using the low-frequency transformer design. That is, it is possible to adjust the output power level fluctuations of the load end. One of the major challenges faced in the design process, the need for efficient implementation of this architecture and high quality sine wave output of a frequency, voltage and harmonic distortion specification.
In addition, how discrete inverter AC side parallel and switch, customers are also facing a number of challenges. Because discrete inverter has played the role of the voltage source, it will produce a unique stable output voltage and current regulation according to the connected load. Therefore, when connecting two or more voltage sources which are not synchronized with each other, will cause the asymmetric load and the current flowing between the voltage source does not flow into the load. This will result in power loss and to generate reactive power. More worryingly, this current may also damage the power.
If there is a slight phase shift between two voltage source, this asymmetry may also occur, leading the voltage difference between the two voltage source and causing the voltage source is directly connected to the AC side. This is because the resistance is very low, resulting in a very large current is generated between the inverter. To solve this problem, the customer uses a very fast and precise control and communication algorithms.
view of the multiple discrete inverter parallel operation work needs, customers must put forward a set of modular design concept. Standby inverter working with standard inverter ((DC-AC), http://www.gridtieinverter.de/, which uses the same power supply electronic circuit and generator to charge the battery by the AC power supply (AC-DC) currently on the market without any models inverter can support this feature and relying on the high-frequency transformer architecture must be developed in order to achieve these goals, the new interface and control strategies. block diagram in Figure 1 is the most apt description of this concept. the client idea of ​​inverter The control system includes four different functional modules, is controlled by three different signal controller:

1. DC-DC
2. DC-AC
3. display and user interface
after market a wide range of digital signal controller (Digital Signal Controller, DSC), customers choose Microchip Technology the dsPIC (r) DSC. The dsPIC DSC with power-friendly peripherals, such as counter pulse width modulation (Pulse-Width-Modulation, PWM) module, based on the analog comparator feedback and coordination ADC (Analog-to-Digital Converter, ADC ) sampling; addition can achieve fast multiplication in a single clock cycle. The combination of these features makes the dsPIC30F DSC cope customers inverter required high execution rate of the control loop algorithms.
In addition, these highly integrated DSC eliminate many external components, such as reset controllers, memory chips, ADC and Controller Area Network (Controller Area Network, CAN) controller. Execution rate by providing up to 30 MIPS, dsPIC30F DSC ensures that enhance the efficiency and reliability of the inverter system. Another advantage of DSC is to support a variety of operating voltage (2.5V-5.5V), ensure the follow-up to the successful upgrade.
DSC also has a variety of flash memory and RAM capacity, and with a variety of connectivity options, which also helps to achieve a flexible modular inverter design. For example, in the DC to DC power level functional modules, dsPIC30F5015 DSC control battery input and high-frequency transformer between the high-frequency level. The client also uses this device to accurately measure the battery voltage and current,power inverter. DC to AC power stage modules using dsPIC30F6010A, used to power electronic circuit through a proportional-integral (Proportional Integral, PI) control loop (patent pending).
The
dsPIC30F6010A connected through the CAN bus and the front panel, and a display control for the inverter dsPIC30F5011. It will also be adjusted according to the user's instructions functional mode of the inverter. Customer specifically selected the dsPIC30F5011 to perform this task, because it is equipped with 66 KB of flash memory and a CAN interface. In addition, the dsPIC30F5011 the on-chip flash memory can help storage inverter multi-language user interface graphical icons. With the front panel navigation keys,Grid tie inverter, the user can easily navigate the various operating modes and menus.
These inverters are highly stable, fast response, and based on the high-frequency transformer technology and modular design. The user can also these inverters in parallel - in the three-phase environment, each phase can be up five inverters in parallel, i.e. the system can be equipped with a total of 15 inverter.
through the selection of Microchip's dsPIC30F DSC, customers to design a compact, multi-functional inverter, without being connected to the public grid can be self-powered,Grid tie inverter.

Figure 1: Functional Block Diagram of discrete inverter

Bipolar full-bridge inverter control

full bridge inverter is a full bridge (Full Bridge) PWM DC / DC converter's main part, its main circuit is shown in Figure 1, it is the tube by four switches V1 to V2, and its Anti-parallel diodes D1 ~ D4, and the output transformer Tr, and other components. The input DC power supply voltage Ui, the output AC voltage U. The primary winding of the transformer Tr, two midpoint of the bridge arm connected to the A and B two turns of the primary winding of the transformer is W1, the secondary winding turns W2,Grid tie inverter, and a variable ratio Κ = W1/W2 is. The full bridge inverter may be used bipolar control, finite bipolar control and phase shifting control mode.
1. Bipolar control mode
bipolar control
full-bridge inverter waveform shown in Figure 1 (b), (c). The switch tube V1 to V2 is used in the PWM control mode. V1 and V4 lead in the first half of a switching period TS weeks, switch to pass on-time TON, DU is the duty cycle, the latter half cycle switch V2 and V3 conduction, conduction time TOn. Switch V1 and V4 conduction Excluding switch-state voltage drop, the voltage on the primary winding of the transformer for UAB =-Ui; switch V2 and V3 conduction, the voltage on the primary winding uAB =-Ui; switch tube V1 and V4, and V2 and V3 are off,power inverter, the voltage on the primary winding UAB = 0, and the open circuit of the transformer secondary, the primary winding of the transformer on the waveform of the voltage UAB Fig 1 (b) shown is a square wave voltage. Adjusting the conduction time of the switch tube, i.e., to adjust the duty ratio DU, can be adjusted voltage UAB pulse width, so as to achieve the purpose of adjusting the voltage UAB RMS size. The secondary voltage U2. UAB same waveform amplitude Ui / K. / p>
the secondary access resistive load RLd, flowing through the load current is isO. Current is, waveform voltage UO, UAB, the same amplitude. IP waveform of the transformer primary current and secondary current is the same, and its amplitude. This equation also can be written in R1, converted to the primary value of the secondary load resistance RLd; Found that, if the transformer is an ideal transformer, which is connected to the transformer secondary the load resistor RLd with without transformer directly connected to the resistor R1, while at both ends of the A, B the effect is the same. Therefore, when the switch tube V1 and V4 conduction, flowing through the current of the V1 and V4, V2 and V3 conduction switch tubes, flowing through the current V2 and V3, the switch tube V1 ~ V4 antiparallel diode D1 ~ D4, there is no current flow.

Figure 3-29 bipolar control mode
If the inductive load L is connected in the secondary of the transformer, when the switch tube V1 and V4 conduction, the transformer primary voltage UAB = Ui, of secondary voltages UO = K0 - the role of the voltage UO, the load current from zero began to increase, the rate of increase, http://www.gridtieinverter.de. This current, i.e. switch tube V1 and V4 will be off reaches a maximum when the switch tube V1 and V4 off, this current can not be a sudden change occurs, and will continue in accordance with the direction of the original flow. It will make the diode D3 and D2 conduction, so the voltage UAB =-Ui, Uo polarity reverse. Under the action of a reverse voltage, the load inductor current will be reduced to the same, the rate of increase of the reduced speed with the switch tube V1 and V4 opened. In this case, the primary and secondary transformer voltage waveform, and resistive loads, there is a great difference, the emergence of a shaded area. UAB: pure inductive load area of the shadow, and the resistive load when the area of the same size. Therefore, the waveform of the output voltage Uo is determined not only by the conduction state of the switch tube v1 and v4, but also related to the nature of the load. When the duty ratio DU ≥, i.e., the conduction time of the switch tube V1 and v4 Ton ≥ Ts / 4,power inverter, the waveform of the voltage UAB becomes a square wave pulse width of 180 ° in electrical angle. I.e., when DU in the range of ~ 1 changes,Grid tie inverter, the voltage UAB and Uo is always 180 ° pulse width of a square wave, from the duty cycle affect Du changes. From the above analysis, the full-bridge inverter should not be used in the inductive load such a pulse width control mode.

traditional fuel cell vehicles with the

traditional fuel cell vehicles with the DC / DC converter and the post-stage DC / AC converter with the regulation, realize the wide scope of multi-method exchange motor speed control,http://www.gridtieinverter.de/, the maximum output current of the DC / DC converter for fuel cell with power restraint, in order to maintain the fuel cell, while a voltage regulator regulating system line; the DC / AC converter to play the role of the power conversion master, on the system bus to electrical energy is changed to electrical energy suitable for motor running, while gripping the motor the operation, to form a model of two energy change.

traditional hard Boost topology boost switch conduction is large due to the topology boost factor than the verge, so switch conduction time is too long to switch cut-off time is too short, resulting in the loss and temperature rise is too large, prejudice to applicable limits the regulator scale. However often taken inverter installed facing due to the boost chopper circuit rated participate Boost, added system cost down conversion effectiveness; any cause of control failures or electromagnetic annoyance level of inverter tube straight through the destruction of the switch tube ; in order to prevent the switch from pipe straight to participate in the death zone affect the output current waveform, there is the problem of the large number of harmonics.

individual, two-stage efficiency is lower than the single-stage system. The new Z-source network can be applied a strange passive network buck conversion efficacy, but also insist on a single-level structure and high potency, have a good discussion. Z-source network pass-through time when the input voltage of the fuel cell is low, the introduction of work in boost mode; without adding direct time when the input voltage is higher, the Z-source network operating in buck mode. Thus, the proposed Z-source inverter network can be well adapted to the wide scope of the automotive fuel cell output voltage changes. Take Z-source capacitor voltage closed-loop control, solid given the fair, so that the voltage and the output voltage of the DC bus to adhere firmly to the capacitor voltage value.

 

traditional Z-source inverter, there are some disadvantages, by introducing a higher functions of the new Z-source inverter, the Z-source inverter in the traditional structure basically function more perfect, more satisfaction in fuel some requests cell vehicles with high discuss the value with use value. Its restraint can through the use of the voltage space vector modulation scheme, the longitudinal zero vector is applied to the role of the conventional zero vector interval, may simultaneously achieve gripping of the DC voltage does not affect the conditions of the effective output voltage vector relative sinusoidal pulse width modulation and other measures show the upper hand. However, the the traditional SVPWM way north to condition, helpless direct use of the Z-source inverter. To solve this problem, this paper given implementation. The new high-performance Z-source inverter topology structure, absolute in the traditional Z-source structure, a DC voltage side switch,power inverter, so the switch to master their be enunciated,Grid tie inverter.

1 Z source inverter

11 traditional Z-source inverter topology and working principle

voltage three-phase Z-source inverter main circuit topology shown in Figure 1.

。

Why choose flyback topology structure

premise Vin = 25 to 125V , Vout = 125, Iout = 32
, why use flyback topology ?
many books have mentioned , The flyback topology practical power below 150W , detailed the cause , however ,power inverter, is rarely profiling , I try to do the instructions . Parse the switch , magnetic devices , capacitors from three aspects .
lower switch (MOSFET). Assuming the input voltage constant 60V, situation , ibid . Appropriate, flyback ,Grid tie inverter, forward , half-bridge selection mosfet withstand voltage with flow through maximum rms current of the mosfet from two aspects .

visible fantasy situation , three topological differences are not body had the lower mosfet conduction losses ( Watch out half-bridge applications two power mosfet ) , switch to another loss , switching loss , the derivation of the formula see EXEL documents . Assuming enlightened off a similar loss , inductance is infinite , then figuring the formula is as follows
flyback

The positive shock
   
half-bridge


can be seen from the formula , in only for the case of an input voltage point optimization , the flyback switching losses , with the half-bridge does not forward differences , which is the limit flyback high power applications a cause, http://www.gridtieinverter.de/

Using an example of the power inverter power

power inverter power is a possible DC12V DC convert AC220V AC mains similar for ordinary electrical applications, is a convenient power converter. The electricity power inverter universal use in, it can be used in various modes of transport, such as cars, all kinds of ships and fly is in the areas of solar and wind power generation, the inverter can not be replaced. Power to master the system reliable power systems and equipment is reliable, efficient operation of the protection level is power restraint system necessary to have the insurance and reliable holding power,power inverter. Power system for the protection of the substation, such as backing machine sub-station RTU, communications equipment can work uninterrupted AC power outage, engineering practice normal UPS power supply as an important solution, but there are small capacity UPS power supply, prices are too lack of high failure rate, protect large, and thus integrated automation substation can be taken power sine wave inverter (hereinafter referred to as the power inverter) to replace the practice of uninterrupted UPS power supply, its strengths are as follows

1 down power inverter system operation and maintenance expense
integrated automation substation
now run, most of the individual set backed by monitoring computer, communication equipment such as microwave and fiber optic machine, such monitoring communication equipment working power in exchange for the power to do the uninterruptible power supply four remote requests to satisfaction, the equipment shall be solely the installation of an uninterruptible power supply (UPS) with battery pack. Installation of inverter power substations can be directly applied large-capacity battery system with DC power supply exchange power and frugal investment outlay than the UPS power supply plan to prevent the repeated investment in batteries to reduce the protection of the workload, decline in the running capital.
2 progress power inverter power supply securely
DC power system installed
substation, high reliability, long life, and thus the DC Energy + inverter program, application of the DC power system monitoring functions and inverter communication efficacy afar real-time monitoring small battery capacity, power inverter running condition, solve the practice UPS power monitoring, easily rendered battery destruction not timely invention issues. Skin care products because of the large capacity battery by the substation DC power system, grid power greatly extends uninterrupted power supply time, really play the role of the emergency power supply, improve the reliability of power supply.

3 power inverter power supply peace
power inverter is a new generation of DC / AC power products, input 220V DC 220V, 50Hz sine wave AC output, input and output terminals are completely isolated from the mains to avoid the impact of the stability of the mains load complete contentment substation sub station RTU request of the working power of the communications equipment and computer equipment, and complete with mains isolation, but also to prevent the power supply caused by lightning overvoltage the board destroyed Incident, progress load insurance.
super-isolated output
because the new generation of DC / AC power inverter, super anti of annoyance 88261baccd0b086d5f574f2af259,Grid tie inverter, powerful communication efficacy in rural comprehensive initiative substations take DC energy + inverter plans exist than good running economy,firmly and peace, to realize unattended monitoring equipment working power requirements. http://www.gridtieinverter.de/

Welding machine of IGBT series welder

power inverter
inverter welding machine works
important
inverter welding machine inverter inverter welding power source, also known as arc welding inverter welding power source is a novel. -Frequency (50Hz) alternating current first into DC rectified and filtered by the rectifier, and then through the high-power switching electronics (SCR SCR transistor GTR FET MOSFET or IGBT) reverse into how many kHz ~ How many ten kHz IF AC,Grid tie inverter, via the transformer at the same time reduced to tens V voltage suitable for welding, and a stable DC welding current is again rectified and filtered output commensurate reactance.
transform order can briefly showed
-frequency exchange (rectifier filter) → DC (inverter) → IF AC (buck, rectifier, filter) → DC.
is AC → DC → AC → DC
Because the exchange of electricity in the inverter is decreased, because of its high frequency, the inductance large,http://www.gridtieinverter.de/, the active power in the welding circuit will be greatly decreased. So rectified again. This is the Inverter Welder common currently the mechanism.
The fundamental characteristics of the arc welding inverter characteristics of
power inverter is a high operating frequency, which bring all sorts of advantages. Since the transformer either the primary winding remains the secondary winding, its potential E and the frequency f of the current, the magnetic flux density B, the core cross-sectional area S and the number of winding turns W follows the associated E = 444fBSW
the winding terminal voltages U approximation that is E, i.e.
U ≈ E = 444fBSW

 

when U, B conclude, if the progress F, S decrease reduced, W, and therefore, the component with the volume of the transformer can be greatly reduced. Will be able to make the machine's components with volume significantly reduced. Frequency of progress and the remaining factors bring many strengths to be compared with conventional arc welding power source, the following important features
1 small size, light weight, thrifty information, carry, move convenience.
the
2 energy efficient, the effects of which can be reached from 80% to 90%, than traditional welding saving more than 1/3.
characteristics
3 moving easily arc, arc solid, weld forming decency, small splash.
4 suitable for robot joint, composed of active welding produced system.
5 a machine used to achieve a variety of welding and cutting processes.
welding machine IGBT series welder works
power switch analogy
common power switch is a thyristor, IGBT, FET, etc.. Thyristor (SCR) of the lowest switching frequency is about 1000 times / sec, the ordinary is not practical for high frequency operation of the switch circuit.
effect transistor characteristics

FET raised strengths in its high switching frequency, the second can switch more than 50 million times above normal in 500V, pressure, temperature 150 ° C (die), and on-resistance pipe low loss switching devices of fantasy, especially suitable for high frequency circuit switching device applications.
However the FET operating current is small, and a high of approximately 20A low individual in 9A or so, limits the maximum current in the circuit, and the encapsulation situations because the FET, such that its pin creepage interval ( conductor to another conductor the nominal interval) smaller, easily breakdown in the environment under high pressure, the conductive pin between destruction machine or persecution personal insurance.
IGBT characteristics
IGBT bipolar insulation effect tube, symbol and equivalent circuit diagram is shown in Figure 111, the switching frequency between 20KHZ ~ 30KHZ. But it by a large current (100A), and outside the package pin pitch, creepage distances can resist the impact of environmental high pressure, safe reliable.

Why choose flyback topology structure

premise Vin = 25 to 125V , Vout = 125, Iout = 32

why use flyback topology ?
many books have mentioned , The flyback topology practical power below 150W , detailed the cause , however ,power inverter, is rarely profiling , I try to do the instructions . Parse the switch , magnetic devices , capacitors from three aspects .
lower switch (MOSFET). Assuming the input voltage constant 60V, situation , ibid . Appropriate, flyback ,Grid tie inverter, forward , half-bridge selection mosfet withstand voltage with flow through maximum rms current of the mosfet from two aspects .

visible fantasy situation , three topological differences are not body had the lower mosfet conduction losses ( Watch out half-bridge applications two power mosfet ) , switch to another loss , switching loss , the derivation of the formula see EXEL documents . Assuming enlightened off a similar loss , inductance is infinite , then figuring the formula is as follows

flyback

The positive shock
half-bridge

can be seen from the formula , in only for the case of an input voltage point optimization , the flyback switching losses , with the half-bridge does not forward differences , which is the limit flyback high power applications a cause , http://www.gridtieinverter.de/

IGBT AC drive inverter design

energy into the process known as inverter from AC power and DC power from AC electrical energy into DC process called rectified DC into AC electricity. The inverter is a complete DC to AC energy conversion device. the AC motor
generally use the AC - DC - AC inverter power supply, grid AC into DC rectifier, filter,power inverter, then through the inverter DC into AC power, to Motor power supply. Therefore, the inverter is one of the key technical device. With the development of semiconductor devices, IGBT increasingly being applied to the AC drive technology. The AC drive constituted by the paper mainly analyzes IGBT form, including the main circuit structure of a main circuit of the inverter, the realization of the drive circuit and the snubber circuit protection.
main circuit structure schematic
Figure 1 is a structure schematic diagram of a typical inverter. It consists of three parts: the inverter circuit, driver protection circuit, control and signal acquisition circuit.

inverter circuit is mainly responsible for the electrical energy into the upcoming DC input available for the motor load can be transformed into three-phase alternating current electrical energy to provide energy to the motor. Figure 2 shows the schematic diagram for the inverter circuit, the inverter circuit comprises six insulated-gate bipolar transistor T1 ~ T6 and freewheeling diode D1 ~ D6. T1 ~ T6 through shutdown input DC power by controlling the IGBT tube reverse into a rectangular wave of adjustable frequency AC output to a three-phase motor. Freewheeling diode D1 ~ D6 when T1 ~ T6 is turned off by the conduction reflux to the DC power supply is provided for the regenerative current when the motor braking channel release passage is provided for the electrical energy stored in the motor coil; ,Grid tie inverter.


2 protection the absorption circuit structure
due to the presence of distributed inductance circuit, combined with IGBT switching speed, and contrast when the IGBT is turned off and then the reverse recovery diode reverse-phase recovery, will generate a great surge voltage Ldi / dt thereby threaten IGBT security. Therefore, measures must be taken to suppress the surge voltage to protect the IGBT is not damaged. Retrofitting way to protect absorption circuit can be used to suppress the surge voltage. The schematic in Figure 3, the protection absorption circuit has a good effect of suppressing, having the advantages of a small loss occurred protection absorbent,http://www.gridtieinverter.de/products_show.asp?id=183

2.1 protection circuit schematic analysis
to switch T1 off moment as a starting point for analysis of the absorption circuit works, the course of their work can be divided into: linearization commutation, busbar parasitic the inductance Lp resonance energy absorption capacitance Cs release point of three stages.
linearization commutation stage shutdown signal is received from the switch tube T1 start to the end of full-cutoff switch T1. Flow through the shunt the bus parasitic inductance Lp busbar current through T1 and snubber circuit branch.
switch T1 completely the commutation phase
online after deadline. At this time, the main circuit parasitic inductance Lp and absorption resonant capacitance Cs, Lp the stored energy is transferred to the Cs. When the voltage on the snubber capacitor reaches the maximum value, i.e. the resonance peak, the resonant current i is zero, absorption circuit diode D2 is turned off, the clamping voltage to prevent oscillation.
after the end of the second stage, the absorption overshoot energy discharge through the the absorption resistance R, the power supply and the load capacitance Cs. Approximate that during the discharge process, the load is a constant current source.
2.2 component parameters selected
a. snubber capacitor Cs select
the buffer capacitor Cs
buffer circuit capacitance value:


the
wherein L is the parasitic inductance of the main circuit, the collector current Io for the IGBT is turned off, VCEP eventually reaches a value in the voltage of the buffer capacitor, Ed is the DC supply voltage.
b. the value of the snubber resistor Rs
buffer resistor role in IGBI next before shutdown the buffer capacitor charge to release. IGBT next action before, in 90% of the storage charge discharge conditions, the snubber resistor value formula should satisfy the following formula:


where f is the switching frequency.
3 driver circuit structure
to ensure reliable IGBT operation, the drive circuit plays a vital role.
3.1 IGBT drive circuit requirements
basic requirements
IGBT drive circuit are mainly the following:
(1) the driver circuit must be extremely reliable, to ensure that the charge-discharge circuit to provide a low impedance for the IGBT gate capacitance;
(2) meet the switching characteristics and reactive the consumption allowed case, the gate resistance can be suitably increased, for limiting transient voltage drop spikes;
(3) driving circuit kHz level able to pass a high-frequency pulse signal; < br /> (4) IGBT Gate pole emitter voltage limit voltage drop is ± 20V. Usually selected forward drive voltage is +15 V, and the reverse drive voltage is-8V.
a drive circuit
3.2 M57959L
According to the design principle of the driving circuit, according to different requirements can be designed to various forms of driving circuit. The common driver circuit has a driving circuit of discrete components, and application specific integrated drive circuit. Relative to the drive circuit with discrete components, application specific integrated drive circuit anti-jamming capability, high degree of integration, speed, perfect protection function drive IGBT best.
M57959L hybrid integrated IGBT driver for Japan's Mitsubishi, the internal principle structure shown in Figure 4. It consists of a high-speed optical isolation input, high dielectric strength, compatible with TTL level. Short-circuit protection circuit built-in timing logic and the protection delay characteristics. Negative when the chip is powered by the positive and negative power to overcome the single power supply voltage instability shortcomings, drive power can to drive 200A/600V or 100A/1200V IGBT module. By M57959L a drive circuit shown in Figure 5.




Note gate resistor value should be used. The value of the gate resistor Rext can affect the oscillation suppressing effect, slowing the switch opening when the di / dt, and improve current undershoot waveform to reduce the surge voltage,power inverter. From the safety point of view, should Rext whichever is greater, but the larger the Rext impact switching speed, increasing the switching losses,Grid tie inverter; increase the operating frequency, should take the smaller value. Meet the switching frequency, whichever is greater Rext.
installation and layout of the main circuit
IGBT switching frequency is very fast while the high power IGBT constitute the other parts of the inverter will generate strong interference. These disturbances not only affect the normal working of the circuit, and even may cause the inverter instantaneous short circuit damage. Therefore, pay enough attention to respond to electromagnetic interference, and reasonable installation and layout to reduce electromagnetic interference.
common interference and corresponding measures are:
isolation powered suppression of
(1) IGBT switches interference due to the impact of distributed capacitance and coupling inductance of the power supply transformer, a strong spikes generated when one of the IGBT is turned on or off by the distributed capacitance (inductance) interfere with other the normal work of the IGBT. Accordingly, each of a trigger circuit of the full-bridge inverter must be isolated from the power supply to suppress such interference.
(2) due to the leakage inductance of the average operating current and instantaneous peak current of the inverter, inverter circuit, even a small lead inductance can not be ignored. If not carefully designed PCB layout flux PCB wires through the closed form current. To this end, the following measures can be taken to suppress interference:
a, an IGBT trigger circuit element should be concentrated in a narrow area, avoiding to cross each other;
b, the same phase of the trigger circuit should be adjacent, while the distance between the two groups should be relatively distant;
c, between the PCB and IGBT leads should be as short as possible and mutual stranded.
5 IGBT voltage and current parameters selected
the absorption circuit
in protection, When the the T1 turns, T2 deadline, T2 withstand voltage Uce2 is:
consider grid fluctuations of + / -10%, the T2 ripe voltage Uce2:
take into account the open circuit off instantaneous voltage and IGBT module withstand voltage of 50% to 80% margin should be left in their chosen the module voltage BVce should to:
consider the fluctuations in the grid, the startup current spikes the selected IGBT module Icm for:
wherein, Pn is the inverter output power. δ is the pulse duty ratio, η is the efficiency of the inverter.
6 Conclusion
the
This paper describes the IGBT drive a motor drive circuit, the buffer should pay attention to the problem of absorption composition and parameter selection as well as the main circuit installation and layout of the circuit with the main circuit of the inverter and IGBT parameter selection, the actual application in inverter design value.

Cascade inverter - based photovoltaic power

1 Introduction
Currently, the traditional single-stage or multi-stage structure of solar photovoltaic grid system deficiencies: grid inverter switch operating frequency is relatively high, a larger loss; work properly for the inverter, photovoltaic cells need the series to a sufficient voltage level, not only to make the switch voltage stress, and reduce the reliability of the system, the system the anti-Battery local shadow diminished capacity; centralized MPPT strict large photovoltaic grid system, in order to improve the reliability of the system and efficiency, avoid more solar photovoltaic cells connected in series, the literature suggests that a step wave and current instantaneous value feedback cascade inverter for hybrid control to achieve grid-connected PV. On this basis, the control of the the cascade inverter photovoltaic power generation system based on hybrid control strategy, double loop control parameters of the instantaneous value of the feedback unit design is based on the hybrid control cascade inverter PV system design theory and implementation of reference, the theoretical analysis and experimental verification,power inverter.

2 photovoltaic power generation system control strategy
the control system
2.1 Structure
two cascaded inverter PV grid power system topology shown in Figure 1. Figure previous stage is a DC / DC dual tube interleaved Boost circuit, the rear stage is composed of from 2H bridge cascaded inverter. The circuit consists of N + M a 2H bridge unit cascade. 1 ~ N 2H bridge for the the ladder wave control, N +1 to N + M a 2H bridge unit for the current instantaneous value feedback octave phase-shift the SPWM control or current hysteresis tracking control. Due to space limitations, here only ladder wave and current hysteresis hybrid control system analysis.

2 ladder wave and current hysteresis tracking mixed control block diagram. S 1 to N +1 of DC / DC converter unit to the voltage of the photovoltaic cell array to boost and to complete the photovoltaic cell MPPT. 1
N2H bridge unit the trapezoidal wave control, N +1 2H bridge unit for voltage and current double-loop control, current inner hysteresis control. Phase-locked loop (PLL) to network current iL and grid voltage ug same phase reference of the PLL circuit is given multiplied by the voltage output of the outer ring,power inverter, the inner ring is the current input reference current. The current iL comparison error signal is amplified by current amplifier via hysteresis control, generating the control signal of the N +1 2H bridge unit. A first N +1 2H bridge unit output voltage us (N +1) should be 1 ~ N 2H bridge unit, the output of the staircase wave voltage in phase with the PLL,http://www.gridtieinverter.de/index.asp, DSP calculated conduction pulse, so that before the inverter N ~ 1 The unit width of the output voltage respectively (θN ~ π-θN), (θN-1 ~ π-θN-1), ..., (θ1 ~ π-θ1), i.e. operating in different modes.
2.2 cascade inverter unit control strategy
in Figure 2, the calculated error of the actual voltage value of the DC bus voltage reference value and the sampled amplitude command Iref of the DC / AC inverter output current is obtained through a proportional-integral link, then Iref with the grid voltage synchronization unit sinusoidal signal sin (ωt) is obtained by multiplying the output current command value Irefsin (ωt), then Irefsin (ωt) with the sampled value of the error through the current regulator, the hysteresis comparator through the drive circuit to control the first N +1 2H bridge unit DC / AC inverter switch.

when ug IL noninverting,Grid tie inverter, the inverter output voltage in phase ahead ug. Therefore the 1 ~ N2H bridge unit output the staircase wave voltage with the instantaneous value of the output voltage of the feedback control of the 2H bridge unit us (N +1) the same phase, gives us (N +1) by the PLL is in phase with the ladder Boji Bo The voltage is then sampled by DSP real s 1 to the N2H bridge unit DC bus voltage, the calculated conduction pulse each 2H bridge unit.
3 instantaneous value the feedback unit bicyclic control analysis
3.1 instantaneous value of the the feedback cascade inverter unit current inner loop design
current inner tri-state the DPM the current hysteresis control, control block diagram shown in Figure 3.

type I system design current regulator. In addition to considering the fast-track the performance of the current inner grid-connected inverter the bicyclic control system, the inner current loop bandwidth of at least 5 to 10 times the voltage loop bandwidth. When the output inductor 25 mH, inductor equivalent resistance is taken as 0.4 Ω take 0.1 ms, Ts, ki is 16. Single P-loop direct current control current inner loop frequency response and the step response is shown in Figure 4.

be seen from Figure 4a, the current closed-loop bandwidth is greater than 10 times the fundamental frequency high the tracking steady accuracy of the fundamental current; seen from Figure 4b, the current closed-loop response is fast, less than 1 ms. Outer voltage, the current inner loop can be equivalent to a controlled current source, and its transfer function can be expressed as FIG. 3B.
3.2 instantaneous value feedback the the cascade inverter unit voltage outer Design
feedback means and the DC input power
set the instantaneous value of the total output power of the cascaded inverters, that is fed into the grid power λ (λ <1) times, the inverter loss is ignored and that the input power of the inverter DC is equal to the output power, namely:.

Figure 5 is an outer voltage control block diagram.

The first-order low-pass filter in
figure GLPF be used to filter out the harmonic components in the DC bus voltage, so that it does not participate in the feedback. PI regulator is set to: Gv = Kpv (τpvs +1) / s, low-pass filter is set to: the GLPF = 1 / (TLPFs +1), the voltage open-loop transfer function is:

The inverter is designed for a typical type II system: take TLPF = T2 = 10ms, λ = 0.435, the Udc (N +1) = 160V, KIF = 0.2, CN +1 = 5600μF, then have Kd ≈ 0.42, Kpv ≈ 3.2, PI regulator proportionality coefficient is 0.16. The design parameters are substituted into the formula (3), we can obtain the frequency response of the voltage of the outer ring and the step response shown in Figure 6,Grid tie inverter. Seen from Figure 6a, the system is equivalent to a cutoff frequency of 18.8 Hz (the closed-loop bandwidth) of the low-pass filter, harmonic components of bus voltage can be well suppressed to ensure the quality of the steady-state input current. By the the Figure 6b bus voltage unit step response shows that the voltage adjustment time of about 80ms.

4 experimental results
design of a single-phase inverters based on a cascade of 3 2H bridge unit 10 kWp photovoltaic power generation system. Two 2H bridge unit for the trapezoidal wave control, the input DC bus voltage in the standard light and the ambient temperature, the inverter unit is respectively 80 V, 160 V, 3 2H bridge unit tristate DPM current hysteresis for tracking control, The input DC voltage is 160 V. Grid current filter inductor L = 2.5 mH. Figure 7 cascade inverter-based photovoltaic grid system current closed-loop control of the experimental results. Seen from the figure, the grid current phase with the grid voltage. In the light intensity changes, and net current amplitude command change. Figures 7a, b, respectively, for the current amplitude command experimental waveform 40 A and 60 A, respectively corresponding grid power was 6.22 kW, 9.33 kW. With the light intensity and the increase in net current and power PV output power point tracking.

5 Conclusion
here by controlling the cascaded inverter input DC bus voltage value is constant, to achieve the input voltage control (power control loop) and photovoltaic systems and network control method of the current control (power quality control loop) decoupling verified through simulation and experimental results with theoretical analysis. System to achieve the maximum power point tracking for photovoltaic output to verify the effectiveness of the proposed control method.

Car audio power multiphase boost the settlement

date: 2013-1-18

Car audio amplifiers usually applied boost converter born 18 V ~ 28 V or higher battery output voltage. 100W and 100W high power use more need big boost inductor, multiple levels of output capacitor parallel MOSFET and the diode,www.12vgridtiepowerinverters.com. The power stage is divided into a plurality of parallel phase to reduce a lot of the power component stress, accelerating the load change, such as the response of the bass notes and advances the system effectiveness.
find a pulse width modulation (PWM) controller for 2-phase boost converter is definitely compared easily. Most dual-channel interleaving the offline controller or push-pull controller can be used to directly drive two boost MOSFET of phase. However, in the 4-phase solution, the scale of the controller's choice is more limited. Honored, multiphase buck controller can be easily converted to 4-phase boost converter.
Figure 1 shows the
using TI's TPS40090 multiphase buck moderation 4 a boost-phase, 300W power supply, the converter is designed to dispose of individual will be presented in audio using 500W peak burst. Typically, the in multiphase buck construct, the uniform current through the inductance of the inductive output of the gripper to equalize the electric power of each phase. In contrast, in a multiphase boost configuration, the current sensing is carried out in the device in each FET source resistor. The peak current through each FET equalizer,Grid tie inverter, multiphase grippers average deployment of power at all in the boost phase. From the grasp the gate drive signal to a logic level, and thus each phase request exists a MOSFET driver. In this design, the application of a dual-channel MOSFET driver, such as the UCC27324 to reduce the number of components.

Figure 1 for car audio amplifier 300W 4-phase boost converter
protected against a current limit applied to each phase and multiphase mastered cover temperance uploaded premise of the infringement. Audio utilization have a lot higher than the uniform output power transient peak power needs. Necessary for the flow limit is set high enough to satisfied with the peak power request. External undervoltage lockout (UVLO) circuit also supply another level maintenance, which can avoid the system running in the low battery voltage conditions. Boost power supply when the battery voltage drops, will attempt to supply as many as possible of the input current, this will lead to the dramatic landing of the battery voltage when the battery is running out of power. This situation causes the battery is damaged, the worst case even make battery scrap. Brief and low-cost the UVLO circuit by a reference circuit, a dual-channel analogy with several resistance.
the design, the four phases are 500 kHz switch, and the resolution of 90 degrees synchronization. Figure 2 shows all four phases of the drain - source voltage waveform. Qijiang from each phase of the ripple current in the input terminal and an output terminal, while they at the input and output terminal partially canceling each other. This at the same time reduce the input and output capacitor AC ripple current. In addition, the integrated ripple current to 2 MHz, the phase frequency is four times the frequency of a single phase. Because the lower the ripple current and a higher frequency,power inverter, and the single-phase solutions comparable input and output power capacity in the multiphase solution is much smaller. A more efficient switching frequency also allows the converter more swiftly, to respond to the change of the load current.
power level is divided into a plurality of phase and decrease the stress of each power module. The lower current and additional power to provide a wider spot supply inductance, FET with diode choice areas. Single-phase solution plan unmatched power loss less and wider spread area, thus simplifying the cooling governance. In the case of driving a 300W load, such a four-phase design is to obtain a 94% of the effect, thus achieving the loss of less than 20W.
looking for a can drive more than two-phase boost controller will bring a certain design provocation. The TPS40090 multiphase boost converter is very practical in the use of high-power audio.

interleaved 4-phase boost settlement plan
the Figure 2 2MHz efficient ripple current run results

Based on input voltage regulation

in the energy crisis db500ffb34c7cc94ef22a7536dcd after the energy conversion efficiency and the effectiveness of increasingly high regard. Thus, countries are also diverse formulate a lot of energy norms. From the early full load efficiency to today's four o'clock uniform efficiency. Desktop power converter, for example, more 80Plus gold, silver and bronze medal in the 20%, 50%, 100% load efficiency norms. However, in many other certification specification, the most troubled of R & D staff is often light load and half load effect. This article first volume of half bridge resonant converter the basic operation Plateau reasonable, and clarifies how through regulating reactive the modify stage PFC output voltage in order to progress in the LLC-SRC half-bridge resonant converter light load and half load effect.

to the current use of high-efficiency power converter, for example, conventional hard-switching techniques Hard-Switching helpless satisfaction of the request in the the 80Plus Gold Medal or higher. The major power supply manufacturers diverse inputs developed soft switching techniques Soft-Switching. Which more half-bridge LLC-SRC series resonant converter Half-Bridge Series Resonant Converter most by the blue eyes. Important Plateau due to its easily reached zero voltage switching to reduce switching loss and the the progressive conversion efficiency, a decrease of such as electromagnetic annoyance EMI.

LLC Highland reasonable dissect
The half-bridge series resonant converter in
LLC-SRC structure shown in Figure 1, can be divided into the triplet part. Square wave generator Square wave generator, resonant network Resonant network output rectifier filter Rectifier network.

A square wave generator by the conduction period of nearly 50% Duty cycle drive power switch MosFETQ1 with Q2 to reach output voltage regulation and by gripping the switching frequency square wave voltage to occur,Grid tie inverter.

B resonant network portion is mainly composed by the resonant capacitor Cr, resonant inductor Lr and magnetizing inductance Lm. This series resonant network can be higher harmonic current filter, and the the current angle outdated voltage reached zero voltage switching.

C application of full-wave bridge rectifier or transformer center tap rectifier type with output filter capacitor, the exchange current is converted to DC voltage output. Exchange for the equivalent circuit is as follows



which



when the input voltage changes or output load changes, to adhere to the output voltage of the solid, required by the swap resonant network voltage gain Gain to achieve. Wherein the gain M may be defined as



which



thereby be noted that the resonant network has two resonant frequencies, one composed by Lr and Cr, while the other by the LP and Cr. And gain with the resonant frequency shift from the load change impact. If the operating frequency w = resonant frequency w0 available



Therefore, when the operating frequency is close to the resonant frequency, all of the resonant impedance of the network is simply will that is output impedance. Here is more similar to the traditional series resonant converter,power inverter. The following picture shows the LLC series resonant converter voltage gain curve.



here with the traditional series resonance is the LLC series resonant converter exist two resonant point, and allow the converter between two resonant point.
FIG 4
, when the operating frequency is less than the resonant frequency FS "F0, primary switching crystal MosFET and secondary-side rectifier diode Rectifier are operating in a soft handover Soft-Switching position, in this case, the secondary side rectifier diodes have no reverse reply time trr of loss. But also because of its the current emerging non-continuous conduction scene,www.12vgridtiepowerinverters.com, its said Ripple Current ripple current in the output filter capacitor, so the analogy useful in the output of the current use of high voltage.

when the operating frequency is greater than the resonant frequency fs f0, characterized more similar to the traditional series resonant converter Series Resonant Converter. Fs more on the verge of f0, its smaller side of reincarnation current Circulating Current, thereby so aptly characterized reduce reincarnation current primary side, to reach efficiency optimization. Secondary side output rectifier diode current than last, the tables had absolutely smaller filter capacitor ripple current. So the operating range is more practical in the output of the use of low voltage and high current.

3KW inverter IGBT bridge driver

recently done a 2000W after class , the number of W-3000W SPWM after class can easily be changed , can be a convenient output pure sine wave form control board with two plans , the effects are as follows < / p > 1, the main control board practical unipolar with bipolar SPWM output , just change the number of resistors can be achieved with the substrate to distinguish .

2, DC input 0-400VDC.

3, the output voltage can swap board potentiometer .

4,Grid tie inverter, by the board potentiometer to achieve the largest areas of regulating the output frequency 0 - 400Hz .

5, the board can choose welding Hall electrical propagation sensor for high-precision current detection .

the board power tube temperature detection sheltering .

7, onboard fan initiative dominated interface, can take the initiative to moderation fan start and stop .

8, perfect maintenance of a short circuit , the output can be any short circuit , automatic recovery after the abolition of short-circuit ,www.12vgridtiepowerinverters.com, cold , hot start can be driven by any load , currently only test the lamp load , cold resistance approximate short circuit ,power inverter. Bipolar mode , sudden 2KW bulb , voltage recovery time in 400ms .

board Videos of

level inverter board





master one pictured < / p >



master two pictured < / p >



board back

12V to AC 220V inverter works

Today we introduce an inverter (see Figure 1) mainly by the MOS FET, ordinary power transformers constitute. Its output power depends on the power MOS FET and power transformers, eliminating the cumbersome transformer winding, using suitable for the amateur production of electronics enthusiasts. Here are the works of the transformer and the production process.





circuit diagram (1)

works:

Here we will detail the working principle of the inverter.

, square wave generation

CD4069 constitute a square wave signal generator. R1 in the circuit is a compensation resistor, used to improve the oscillation frequency due to changes in the supply voltage caused by instability. The shock of the circuit is completed through the capacitor C1 is charged and discharged. The oscillation frequency f = 1/2.2RC. The maximum frequency of the circuit as shown: fmax = 1/2.2x103x2.2x10-6 = 62.6Hz,power inverter, the minimum frequency fmin = 1/2.2x4.3x103x2.2x10-6 = 48.0Hz. Due to the errors of the components, the actual value will be slightly different. Other unwanted fat phase, the input connected to ground to avoid the influence of other circuits.





Figure 2

, FET drive circuits.

Since the maximum amplitude of the oscillation signal output voltage of the square wave signal generator is 0 ~ 5V, the full drive power switching circuit, where TR1, TR2 of the oscillation signal voltage is amplified to 0 ~~ 12V. As shown in Figure 3.





Figure 3

, FET power switch circuit.

FET is the core of the device, before in Introducing the part works, briefly explain MOS FET works.

MOS FET has also been referred to as MOS FET, i.e., Metal Oxide Semiconductor Field Effect Transistor (metal oxide semiconductor FET) Abbreviation. General depletion mode and enhanced two. This article uses the enhanced MOS FET, its internal structure is shown in Figure 4. It can be divided into an NPN and PNP type,Grid tie inverter. The NPN type usually referred to as the N-channel type and PNP type usually known as the P-channel type. Figure tube can be seen, the N-channel type field effect its source and drain connected to the N-type semiconductor, the same tube for the P-channel FET with its source and drain connected to the P-type semiconductor. . We know that the the general transistor is the current output by the input current control. But for the FET, the output current is controlled by the input voltage (or field voltage) can be considered that the input current is minimal or no input current, which makes the device has a high input impedance, while this is we call The reason for the FET.





Figure 4

explain MOS FET works, let's look at the process of a P-N junction diode only. Shown in Figure 5, we know that the forward voltage (P Termination positive electrode, N termination negative), the diode conducts the current through the PN junction diode plus. This is due to the positive voltage at the end of the P-type semiconductor, the negative electrons within the N-type semiconductor is attracted flock applied a positive voltage of the P-type semiconductor side, and positrons within the P-type semiconductor side toward the N-type semiconductor side movement, thereby forming a conduction current. Similarly, when the the diode plus reverse voltage (P Termination negative, N terminating positive electrode, when the P-type semiconductor side to a negative voltage, n electrons are gathered in the p-type semiconductor side, the negative electrons are gathered in the N-type semiconductor side, the electrons do not move, no current flows through the PN junction diode cutoff.





Figure 5

For FET (Figure 6), when no voltage in the gate, with the previous analysis, not a current flows between the source and the drain, the FET is in the OFF state (FIG. 6a). When a positive voltage is applied to the N-channel MOS FET gate, due to the effect of electric field, the negative electrons of the source and drain of the N-type semiconductor is attracted and flock to the gate, but due to The oxide film of the barrier, making electronic aggregation (Figure 6B) in between the two N-channel P-type semiconductor, thereby forming a current, so that the conduction between the source and drain. We can also imagine a ditch between the two N-type semiconductor, the establishment of the gate voltage between for them take a bridge, the bridge's size is determined by the gate voltage. Figure 8 shows the working process of the P-channel FET, similar to how it works will not repeat it here.





Figure 6

briefly below the working process of the application circuit of C-MOS FET (Enhanced MOS FET) (see Figure 8). The circuit will be an enhancement-type P-channel MOS field colonels and an enhancement-type N-channel MOS FET used in combination. When the input is the bottom level, the P-channel MOS FET output and the positive power supply is turned on. When the input is high, N-channel MOS FET is turned on, output terminal and the power turned on,power inverter. In this circuit, the P-channel MOS FET and the N-channel FET is always in the opposite state, the opposite phase input terminal and an output terminal. Through this work we can get a large current output. Due to leakage currents at the same time, so that the gate voltage is not to 0V, typically the gate voltage is less than 1V to 2V, the MOS FET i.e. off. The different FET turn-off voltage is slightly different. Think so, so that the circuit will not short out power to two simultaneous conduction.





Figure 8





Figure 9

above analysis we can draw the MOS FET schematic part of the work process (see Figure 9). The working principle is the same as the foregoing, such low voltage, high current, a frequency of 50Hz alternating signals through the low voltage winding of the transformer, the high-pressure side of the transformer to induce a high-voltage AC voltage, the completion of the DC to AC conversion. Note here that, in certain circumstances, such as the oscillation portion stop working when the low-voltage side of the transformer is sometimes there will be a large current through, so that the fuse of the circuit can not be omitted, or shorting.

circuit board shown in Figure 11. Elements may be used by referring to Figure 12. Secondary inverter transformer used for 12V and current of 10A, the primary a refined power transformer voltage of 220V. The maximum drain current of the P-channel MOS FET (2SJ471) 30A, when the FET, the resistance between the drain - source 25 mOhm. By 10A current will 2.5W power consumption. N-channel MOS FET (2SK2956) maximum drain current of 50A, FET, the drain - source resistance of 7 milliohms, through 10A current power consumption of 0.7W,www.12vgridtiepowerinverters.com. Thus we have seen that in the same working current circumstances, The 2SJ471 fever about 2SK2956 4 times. Therefore, in considering the radiator should pay attention to this point. Figure 13 shows an inverter FETs location distribution and connection on the radiator (100mm × 100mm × 17mm) that are described in this article. The FET switch state heat will not be great, for security reasons radiator choice here Shaopian.





Figure 11





Figure 12





Figure 13





Figure 14

inverter performance test





test circuit is shown in Figure 15. Test input power 12V car battery with low internal resistance, discharge current (generally greater than 100A), and provides plenty of input power for the circuit. The test with a load of an ordinary electric bulb. The test method is by changing the size of the load, and measuring the input current at this time, the voltage and output voltage. Their test results, see the curve of the voltage, current diagram (Figure 15a). It can be seen that the output voltage with the increase of the load decreases, the consumed power of the lamp with the voltage change. We also find out the relationship between the output voltage and power can be calculated. But actually changed due to electrical resistance of the bulb with by raising both ends of the voltage change and the output voltage, the current does not be a sine wave, so this calculation can only be regarded as estimates. Load is 60W light bulb, for example:





Figure 15





Figure 16,17

assumed that the resistance of the bulb does not change with the voltage change. R lamps = V2 / W = 2102/60 = 735Ω, so the voltage of 208V, W = V2 / R = 2082/735 = 58.9W. Which can be converted into a voltage and power relations. Pass the test, we found that when the output power is about 100W, input current of 10A. The output voltage is 200V. The inverter power efficiency characteristics shown in Figure 15b,Grid tie inverter. Figure 16 is an inverter continuous 100W load, FET, the temperature rise of FIG. The output waveform diagram for the production of 17 different load reference.

Asymmetric H-bridge five -level inverter and its u

1 Introduction withstand voltage stress level inverter power switch

hybrid multilevel power devices can be used, so the same topology,Grid tie inverter, take full advantage of the power switch to the respective advantages. Asymmetric h hybrid multi-level inverter bridge is the most basic, the most typical topology, its half-bridge power switch can work at the fundamental frequency and high-frequency pwm way, with the traditional multi-level inverter phase The ratio, in the case of the same output level number, reducing the power device, to reduce the switching loss [1,2]. The first asymmetric h bridge five-level inverter, its structural features, proposed a universal modulation strategy. Finally, experimental platform to the asymmetric capacitor clamped h-bridge topology for the experimental validation of the proposed modulation strategy.

asymmetric h bridge five-level inverter

The Asymmetric h-bridge topology in

basic hybrid multi-level topology, the most typical topology, its half-bridge power switch can work at the fundamental frequency and high-frequency pwm way with the traditional multi-level inverter compared in the same level as the number of output and reduce the power devices, reducing the switching loss. The most useful of the three five-level asymmetric h bridge: bidirectional switches asymmetric h bridge, the diode clamp asymmetric h bridge and capacitor clamped asymmetric h bridge, are shown in Figure 1 (a), (b), (c) shown below. Figure 1 (a) of the bidirectional switch five-level inverter through the two-way switches (S5, and d1 to d4) and h bridge (S1 to S4), and outputs the voltage combination of the two DC power supply e Five-level AC voltage; Figure 1 (b) diode clamped five-level inverter, the left half of the bridge for diode clamped Sanden Pingban, bridge and right half bridge two power Pingban bridge, while Figure 1 (c) capacitance clamped five-level inverter,Grid tie inverter, the left half bridge capacitor clamped three the electric Pingban bridge.

traditional multi-level inverter three categories: the diode clamped, flying capacitor the h bridges cascade Schedule for the five-level inverter single phase power devices required comparative table, with traditional the three types of five-level inverter compared to the first three categories topology using voltage stress 1:1 power switch, the topology required power switch up,power inverter; Figure 1 Asymmetric h bridge five-level inverter hybrid applications The voltage stress ratio 1:2 power switch, five-level voltage output less power switch, from the point of view of the number of output voltage level and the number of power switches have a greater advantage than the first three categories topology.

3 common modulation strategy

already

Figure 1 h bridge asymmetric five-level inverter modulation strategy specific sub-harmonic elimination method [3] and a square wave - eliminate harmonics pwm synthesis modulation strategy [4], the former in frequent occasions wide speed range of the motor drive, the look-up table value and the true value of the switching transition time between there is a certain deviation, which need to be high, low-frequency power switching half-bridge separating modulation, calculated high-frequency the modulated wave of the half-bridge of the power switch, increasing the complexity of the modulation strategy. To solve these problems, this paper presents the versatility of a non-symmetric h bridge five-level inverter modulation strategies.

the general modulation strategies

3.1 Principle

used the "half-bridge"

Currently, there are three types: the the two power Pingban bridge hb1, the the diode clamp n electric Pingban bridge hb2, the capacitive clamp type n electric Pingban bridge hb3. Orderly mixing these three types of "half-bridge", constitutes a Universal asymmetric h bridge shown in Figure 2. Figure hbx 'said this "half-bridge" with respect to hbx less resistance to high-voltage power switch work in the the ladder wave modulation Zeyi more low-voltage power switch in hbx pwm modulation state, x is 1, 2, 3, even m standard Mody coefficient of the output voltage of the DC power supply voltage of each level is e. Asymmetric h bridge pwm modulation state the half bridge hbx the power switch withstand e shutdown voltage stress, right half bridge hbx ', the power switch to withstand the maximum voltage stress off need to reach me, limiting its The power switch is only for low-frequency, high voltage devices. In Figure 1, the three asymmetric H bridge five level topology is a special case of Figure 2 Universal asymmetric H bridge when m = 1.

of Figure 2 generic non symmetric the h bridge right half bridge operation at the fundamental frequency of the square wave modulation, the driving signal and the modulated wave zero crossings synchronization. According to the position and the left half bridge hbx output voltage level corresponding to the switching state where the positive and negative regions of the modulated wave, to determine the distribution state of the carrier within a fundamental cycle. The three types of "half-bridge" in the power switch is a complementary pair, so the number of carriers of the the left half bridge hbx's power switch complementary pair quantity, that is, DC power supply subscript Mody coefficients m. Asymmetric h bridge topology common modulation strategy in Figure 3, the carrier cm, cm 'according to the output voltage level corresponding to the switching state orderly laminating distribution. Positive and negative area, the position of the carrier laminate need to be determined according to the output level corresponding to the switching state,www.12vgridtiepowerinverters.com, the carrier modulated wave Vref where CI layer layered partition pwm modulation obtained on the PWM driving signal complementary to the corresponding power switch si uo makes the Asymmetric h bridge output with carrier ci corresponding the pwm level of layer. And within this time region, and other power switches are in the OFF state of the ON / OFF.

3.2 Asymmetric h bridge five-level inverter universal modulation strategy

Figure 1 Asymmetric h bridge five-level inverter working mechanism available, the right half of the asymmetric h bridge bridge power switch are working at the fundamental frequency, the left half-bridge power switch drive signal pwm complementary right, for example, Figure 1 (a) in the power switches s1, S5 (or S2, S5) complementary; Figure 1 (b) power switches s1, s3 complementary and S2, S4 complementary; Figure 1 (c) power switches S1 and S4 complementary and s2, s3 complementary,power inverter. Figure 3 common modulation principle of asymmetric h bridge asymmetric the generic modulation principle, the five-level inverter h bridge as shown in Figure 4. Asymmetric h bridge five-level inverter in the positive half cycle of the modulated wave, requires two-way vertical distribution of the carrier c1, c2, the modulated wave and the two-channel carrier spwm modulation, respectively, corresponding to the non-complementary power switch S1, a drive signal S2, so that the inverter output of the five-level corresponds to the carrier c1, c2 two PWM level layers 1,2. Right half bridge S5 a drive signal by the modulation wave, the zero-crossing point decision. In the negative half cycle of the modulated wave, the carrier staggered distribution to the negative region of the modulated wave, the completion of the negative half cycle SPWM modulation, the output the pwm level of layer 1 ', 2'.

4 experimental results

In order to verify the non-symmetrical the h bridge five-level inverter universal modulation strategy, single-phase capacitor clamped five-level asymmetric h-bridge topology experimental platform, and experimental verification. The DC bus voltage e = 20V, the carrier frequency fc = 2kHz, the modulation wave frequency fm = 50Hz modulation mA = 0.95, RL load, r = 100Ω, l = 63ml.

Figure 5 is a power switch s1, S5 drive signal experimental waveform, power switches S1 to S4 are working at high frequency PWM state power switches s5, s6 work in the baseband state. Figure 6 is an experimental waveform of the inverter output voltage and the clamp capacitor voltage, UO five-level voltage to the inverter output, uo clamp capacitor voltage of the inverter, since the positive and negative half cycle to the clamp capacitor charge and discharge the capacitor voltage smaller fluctuations, but universal modulation strategy makes the clamp capacitor voltage reaches a good balance. Figure 7 is an experimental waveform of the inverter output voltage and load current, il is the load current (at both ends of the resistance r voltage) the RL load so that the load current having a preferably sinusoidal.

5 Conclusion

In this paper, three asymmetric h bridge five-level inverter, based on an asymmetric h bridge common modulation strategy for three asymmetric h bridge five-level inverse change control. Finally, the single-phase capacitor clamped five-level inverter experiment platform, to verify the correctness and validity of the proposed method.

Developed based HPWM dominated skills sinusoidal

1 Introduction

ultrasonic

mounted by ultrasonic power inverter transducer. In recent years, because the research and development of the victory of the new rare earth efficacy data, the production of high-power ultrasonic transducer as possible, but the accompanying high-frequency sine wave inverter power supply products are still rare. At present, the market of high-power sine power inverter are IGBT made in low-frequency, high frequency inverter power most power or duty cycle of the square wave pulse inverter power adjustable. Therefore, high-frequency high-power sinusoidal power inverter has become a bottleneck ultrasonic utilization, makes the development of the power supply has become a pressing problem. Here, the use of the mixed pulse width modulation (Hybrid Pulse Width Modulation, HPWM) control skills MOSFET parallel operation mode, the use of single-chip composed of intelligent control system, high-performance, high-power sine the ultrasonic wave inverter power development in the discussion.

2 system formation

for high-performance, high-power the sine ultrasonic power inverter, and its frequency is 25kHz, the power of 4.5kW. Voltage request is adjustable between 0 ~ 200V, adjustable frequency between 10 ~ 25kHz.

2f672f2b6f77980b075f2b0b40978b65 design

Figure 1 shows the power inverter a block diagram showing the configuration of the system hardware. It consists of two major departments of the AC / DC and DC / AC. AC - DC - AC main circuit, driving circuit, MCU control system, a low-pass filter, display and cover other important links.



main circuit directly powered by 220V mains. The single-phase switching voltage by a thyristor the constant current constant voltage control module will be exchanged is converted to DC of the inverter for supplying a constant DC voltage.

To make the inverter can be a function with the incomparable good sinusoidal output waveform, there need to be greater than the carrier. Because its carrier signal will reach 400 ~ 600kHz, and thus can only use the MOSFET as a switching device. However, the output power of the MOSFET is small and can be taken in order to increase the output power, the way to solve the resistance to high-frequency and high-power MOSFET parallel operation.

inverter partial asynchronous modulation constant frequency triangular carrier signal input sine wave. Grasp the way take HPWM skills. The inverse of the DC voltage pulse signal into a series of amplitude. Amplitude with the pulse width of the pulse signal is always proportional to the modulating sine wave. These pulse signals are filtered via low pass filter, a high-frequency carrier signal. Can be obtained with the modulation wave with the frequency of the sine wave output. Therefore only the transformation of the input modulated wave, can be easily achieved adjustable amplitude, variable frequency sine wave output.

22 microcontroller dominated system

The power supply uses specially designed for the control of the inverter 80C196MC microcontroller as the control center of the inverter. 80C196MC microcontroller internal waveform generator WFG, the CPU time is very short. By P6 port directly output 4 PWM signals for the inverter drive. Formed by 80C196MC and EPROM2764 minimum microcomputer system. Will be given of the ultrasonic frequency and voltage magnitude. As well as the setting of the carrier frequency, and mimic the output unipolar sine wave with constant amplitude pulse width modulation HPWM signal. The display of the voltage amplitude and frequency can be realized. And maintenance of the power supply control.

23 inverter main circuit and HPWM of restraint methods

when running in high frequency the great switching losses of the power tube. The device is easy to damage, limit the power increases. The crucial technical difficulties of the power is in the the high frequency premise How to get high-power variable frequency sine wave output. Inverter difficulty is how to decline the the switch switching losses, du / dt and di / dt stress greatly reduced, in order to achieve the high-frequency inverter. In order to reach these goals. The main circuit of the inverter uses a single-phase full-bridge topology structure easy to implement soft-switching technology. In a controlled manner using the the HPWM control mode. Figure 2 illustrates the topology of the main circuit of the inverter. Figure 3 illustrates the output signal of the four switch control of the drive signal and the inverter.



HPWM to grasp the nature of the way is still a unipolar SPWM control. The output of the inverter bridge is a tri-state output voltage wave shape. The sinusoidal modulating wave and the triangular carrier wave in the positive half cycle of the output voltage of the AC / sectional generating a pulse signal control VS2 and VS4 arm restraint VS1 and VS3 bridge Arm HF complementary off; low frequency complementary off, i.e. VS2 off, VS4 guide through. In the negative half cycle of the output voltage, the exchange of the working status of the two bridge arm. The VS1 always off, VS3 always brought into conduction, VS2, and VS4 high-frequency modulation operation. HPWM control mode, the total two power tube work in the low-frequency case, reducing the switching losses in general,power inverter, this progress in the high-frequency power is extremely favorable. Unmatched individual SPWM dominated. Two leg work alternately in the low-frequency and high-frequency conditions HPWM way, the two leg work symmetrically balanced power tube working conditions, which will extend the life of the power tube, to all circuit robustness additions, there are voltage applications rate, the harmonic content, low switching losses strengths. Because each switch in parallel with a capacitor filter inductance parameter choices appropriate circumstances, the circuit is very easy to achieve zero-voltage switch-off (ZVS), du / dt and di / dt stress greatly landing,Grid tie inverter, complete to to achieve the high-frequency power inverter.





24 driver circuit switch driver circuit latest LM5111 drives can be used. SOIC-8 pin package, and to support the use of input and output stage supply alone break ground and reference voltage pin, leaving the power supply design gate drive configuration. The LM5111 chip peak output currents up to 5A LM5111's two of 5A current drive channel can be individually broken, can also be parallel convergence, the peak output drive current progress to 10A, in order to be able to drive great power MOSFET high effectiveness. LM5111's operating frequency up to 1MHz, enlightened, off delay resolution of 12ns and 14ns. Able to complete satisfaction of the power of the request.

3 software

31 main program

Figure 4 shows the main program flow chart. It includes a subroutine initialization subroutine, HPWM signal, keyboard scanning and display routines. Initialization routine the Application of 80C196MC on stack address and carrier frequency parameters initialization and microcontroller I / O ports, suspension and waveform generator set operating mode. Keyboard given desired output sine wave frequency is displayed by the display program. Subroutine of the voltage signal timing sampling A / D conversion, dynamic, time-sharing the frequency and amplitude of the sine wave value.



32 HPWM signal the subroutine

HPWM is comparable to that generated by the sinusoidal modulation wave with the amplitude of the triangular carrier. Waveform generator core alignment mode, the counting process of the WG-COUNTER constitute an imaginary triangle wave carrier. Sinusoidal modulation wave can be achieved through the look-up table. Because output HPWM wave has symmetry, so long as to establish 0 ° ~ 180 ° of the sine function table. Every 0.15 ° sine function table in order to reach the adequate identification rate, the deployment of a sampling point, each data with 15-bit binary value, accounting for two-byte, half cycle of the output sine 1200 of data sent the presence of starting address for the storage area of ​​the SIGN. Carrier frequency fc, the output frequency is fo, each half cycle of sine wave output is required of N =-fc / FO intersection value, corresponding to the intersection of the i-th sinusoidal modulation amplitude value can be obtained through the look-up table, the address SIGN +1200 i / N.



the triangular carrier at the intersection of sinusoidal modulation amplitudes analogy to to obtain inverter HPWM switch mode. Whenever the peak of the triangular wave carrier (WG-COUNTER = WG-RELOAD) or bottom to the microcontroller the aborted plea, data loading. So, each half cycle of the AC two-phase to obtain hybrid unipolar modulation mode HPWM wave. Figure 5 illustrates HPWM signal generating subroutine flowchart.

4 test results

the main circuit structure, control method, developed an output frequency of 25kHz; carrier frequency of 600kHz; principle prototype output power of 4.5kW. Figure 6a, b shows the filter inductor the rational half load and rational full load current iL and output voltage uo experimental waveforms. The figure shows that half load and full load, uo change smaller have better load swap rate. Figure 6c, d shows the drive voltage inverter bridge unified one leg two power tube VS2 and VS4 ugsVS2 and ugsVS4 the enlarged ugsVS2 and ugsVS4 test waveforms. Visible, as appropriate, to the death zone, unified leg two power tubes are complementary conduction. Power tube drive voltage waveform rebound and landed delay time is extremely short, may contentment requirements. The judge





5 the psionic control system, single-chip high-power ultrasonic power, artificial power frequency and output voltage setting. Simplifies hardware circuit the HPWM signal microcontroller mimic the output, greatly improving the power factor and the effectiveness of the system,www.12vgridtiepowerinverters.com; applied HPWM control mode with ZVS resonant soft-switching technology, the decline in the loss of the switch, restraint and high-order harmonic reduced transducer losses. The experiments show the excellent performance of power, adjust convenient, reliable high. For high-power ultrasonic transducer provides excellent performance in various aspects of the use of ultrasonic power.

Grid tie inverter
power inverter