Generally, the exchange of electrical energy is converted into the DC process called rectification, to complete the circuit of the rectifier function called a rectifier circuit device called a rectifier rectification process equipment or rectifier. Correspondingly, the DC power is converted into electrical energy exchange process is known as the inverter, the complete circuit of the inverter functions called inverter circuit device called inverter inverter process equipment or inverter.
Modern inverter technology is the study of the the inverter circuit theory and applications of a science and technology. It is a practical technology in industrial electronic technology, semiconductor device technology, modern control technology, modern power electronic technology, semiconductor technology, pulse-width modulation (PWM) converter technology disciplines basis. It mainly includes integrated semiconductor power devices and their applications, inverter circuit and inverter control technology into three parts.
inverter classification
The
inverter type of a lot of different classification.
1. From AC power inverter output frequency can be divided into the frequency inverter, IF inverse and high-frequency inverter. The frequency of the frequency inverter 50 ~ 60Hz inverter; IF frequency of the inverter is typically 400Hz to hundreds of kHz; the high-frequency inverter frequency is generally more than a dozen kHz to MHz.
2. Press the number of phases of the inverter output, can be divided into single-phase inverter, three phase inverter, and a multi-phase inverter.
3. The whereabouts of the inverter output power points, can be divided into active inverter and passive inverter. Where the inverter of the inverter output power is conveyed to an industrial power grid, referred to as active inverter; Where the energy output of the inverter output of the to certain electric load inverter called passive inverter devices,Grid tie inverter.
4. Divided according to the form of the main circuit of the inverter, the inverter can be divided into single-ended, push-pull inverter half-bridge inverter and a full-bridge inverter. http://www.gridtieinverter.de/
5. Stars by the main switching element of the inverter type, can be divided into the thyristor inverter, transistor inverter, FET inverter and an insulated gate bipolar transistor (IGBT) inverter. Could be grouped into two categories of "semi-controlled inverter and control inverter. The former, does not have the ability to self-shutdown components in the conduction soon lost control, so called "semi-controlled" ordinary thyristor that fall into this category; latter, you have the ability to self-OFF, ie no device The turn-on and turn-off is available to the control electrode control, so called "full control, power field-effect transistors and insulated the in gate bipolar transistor (IGBT), etc. fall into this category.
6. DC power points, can be divided into a voltage source inverter (VSI) and current source inverter device (CSI). The former, the DC voltage is nearly constant, the output voltage of alternating square wave; latter, nearly constant DC current, the output is also the current of alternating square wave.
7. The inverter output voltage or current waveforms, may divide into a sine wave output inverter and non-sinusoidal output inverter.
8. Inverter control points can be divided into the frequency modulation (PFM) inverters and modulation (PWM) inverter, the pulse width of formula.
9. Inverter switching circuit works hard switching inverter resonant inverter can be divided into fixed-frequency and fixed-frequency soft switching inverter.
10. The inverter commutation points, can be divided into load commutation inverter and from the commutation inverter.
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the basic structure of the inverter
The
direct function of the inverter is the DC can be converted into AC power, and its schematic diagram shown in Figure 1.
The core of the inverter device, the inverter switching circuit, referred to as the inverter circuit. The circuit power electronic switch is turned on and turned off, to complete the functionality of the inverter. -Off of the power electronic switching devices, requires a certain driving pulses,www.12vgridtiepowerinverters.com, these pulses may be adjusted by changing a voltage signal. Generating and regulating circuit of the pulse. Usually referred to as a control circuit or control loop. The basic structure of the inverter device in addition to the above-mentioned inverter circuit and the control circuit, the protection circuit, an output circuit, the input circuit, the output circuit and the like, as shown in Figure 2.
works
inverter. Full-controlled inverter works: as shown in Figure 3, the output is usually used in single-phase full-bridge inverter main circuit diagram AC components IGBT control Q11, Q12, Q13, Q14. By the PWM pulse width modulation control IGBT control turned on or off.
When the inverter circuit is connected to the DC power supply, first Q11, Q14 is turned on, Q1 and Q13 is cutoff, the current from the DC power supply positive output, the Q11, L or flu, the transformer primary coil Figure 1-2 Q14 back to the negative power supply. After the closing of the Q11, Q14, Q12, Q13 is turned on, the current from the positive power supply Q13 transformer primary coil 2-1 electric feel Q12 back to the negative power supply. At this time, in the primary coil of the transformer, forming a square wave of positive and negative alternating use of the high-frequency PWM control, two pairs of IGBT tube are alternately repeated, generates an AC voltage in the transformer. To form a sine wave AC voltage, so that the output AC filter effect due to the LC.
, Grid tie inverter ; When Q11, Q14 is turned off, in order to release the stored energy in the IGBT at the parallel diodes D11, D12 so that energy back to the DC power.
2. Semi-controlled inverter works: a semi-controlled inverter thyristor components. The improved parallel inverter main circuit is shown in Figure 4. Figure, Th1, Th2 working alternately Transistor, to set Th1 first trigger conduction, then the current flowing through the transformer of Th1, the same time due to the inductive effects of the transformer,power inverter, the commutating capacitor C is charged to 2 times the power supply voltage. According Th2 is triggered by conduction, because the anode reverse-bias of the Th2 power inverter , Th1 deadline to return to the blocking state. Thus, Th1 and Th2 commutating capacitor C and then reverse polarity charging. Alternately triggered thyristor current alternately flows to the transformer primary to get alternating current in the transformer secondary.
in the circuit, the inductance L can limit the change of the discharge current to the capacitor C, to extend the discharge time to guarantee circuit turn-off time is greater than the thyristor turn-off time, without the need great capacity capacitor. D1 and D2 are two feedback diode, the inductance L of energy release, it will be sent back to the remaining energy to the power supply, to complete the feedback effect of energy.
inverter technology performance and evaluation of selection
technical performance
Many
characterize the content of the basic parameters and technical conditions for the performance of the inverter, a brief description below only in respect of the evaluation parameters.
1. Rated output voltage
fluctuations allowed within specified input DC voltage, it should be able to output inverter rated voltage value. Stable accuracy of the rated output voltage value is generally defined as follows:
(1) in the steady-state operation, the voltage fluctuation range should have a limited, for example, the deviation does not exceed the rating of ± 3% or ± 5%.
(2) in the dynamic case load mutation (rated load 0% → 50% → 100%) or other interference factors, the output voltage deviation should not exceed rating of ± 8% or ± 10%.
2. The degree of imbalance of the output voltage
In normal operating conditions, the inverter output phase voltage unbalance degree (the ratio of the reverse component of the positive-sequence component) should not exceed a predetermined value, generally %, such as 5% or 8%.
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