Study Of Shunt Active Power Filter Based On Soft-switching Technology

All kinds of power electronic products are widely used in modern industry, which promotes thedevelopment of the industry, but also brings serious harmonic pollution to the power system. As aresult, as a kind of device to restrain the harmonics, the active power filter is developed, which hasremarkable effect in terms of harmonic compensation effect and can real-time compensate all theharmonic waves in one process.For the purpose of the harmonic pollution governance of the power system, this thesis discussesthe shunt active power filter in detail and improves its performance. As a result, the author addsoft-switching technology into the inverter circuit of the active power filter, which will make that theactive power filter adapt to a bigger power system..At the first step, the author studies the structure model of the shunt active power filter and itsworking principle, then divides it into three parts which can be analyzed one by one. In this article,the author employs i_p-i_q method in harmonic detection and operation part, and adopts the controlstrategy which combines with hysteresis current controller and space vector. As for the main circuitpart, in view of expanding the capacity of active power filter and increasing the switching frequency,the author decided to add the soft-switching technology to expand the main circuit structure. In acycle of the soft switch, through the analysis of the voltage and pulse change on the main switch, theauthor draws the corresponding circuit diagrams, lists the differential equation, and calculatescomponent parameters of the main circuit.Then, the author set up the hardware and software system of the active power filter based on theabove theoretical foundation, which provides design thought. In the laboratory a low voltage systemof the Shunt Active Power Filter was constructed based on DSP processor and in the CCSenvironment the software program was writted, including soft-switching interrupt subroutine, andthe system was carried on the debugging.Finally, for testing the accuracy and feasibility of the design, the author establishes thesimulation model of the whole system in MATLAB, and then through the simulation result of theload current waveform of A phase and the voltage waveform of capacitor, we can confirme thissystem design choice of algorithm, the soft switch technology idea is feasible.