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
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