Optimization Design Of Active Power Filter Hysteresis Control

With the upgrading of power electronic devices, Power electronictechnology is also booming. These devices play an important role inpeople’s convenient daily life, saving energy and improving productionefficiency, but most of power electronic devices use nonlinear components, soharmonic problems caused by current transformation also affects us. A largenumber of harmonic and reactive current go into the grid will reduce the powerfactor of the grid, lower power efficiency, and lead to power equipment appearhidden troubles, even causes the problem such as system relay protectionmisoperation. Compared with early passive filter, active filter (APF) in terms ofharmonic and reactive power compensation and purifying power grid has asignificant effect, active filter not only has a small volume but also make areliable performance, so active filter has become hot spot research in the respectof power quality in recent years.The paper based on the three-phase three-wire shunt APF system as theresearch object, introduces the basic principle and the topological structure ofAPF. In terms of harmonic current detection uses the detection method based oninstantaneous reactive power. The current tracking control method is based onthe traditional hysteresis control, through the analysis of the hysteresis principle and model, carries on the optimization design, to improve the instabilityproblem of switch frequency in the original model. This method can effectivelycoordinate system parameters, under the conditions of the variational systemparameter still can realize the precise tracking of instruction current.Build the simulation model of the system under the simulation environmentof MATLAB/SIMULINK. It mainly includes: main circuit, the harmonicdetection and calculation module, current tracking control module. Currenttracking control module has a loop width calculation module, it can beaccording to the real-time feedback system parameter to calculate reasonablewidth value, and by writing S function to give the right switch control signals.By comparing the traditional hysteresis control and optimized control method,the simulation results show that two methods both can accurately track theinstruction current and get the desired compensation effect. In terms of theswitch frequency, we can see clearly that the optimized method can make theswitch frequency relatively stable, so as to make up for the deficiency of thetraditional hysteresis control method.Improve the signal detection circuit and implement experiment under thecondition of the TMS320F2812hardware. Writing the programs include themain program, capture interrupt, A/D sampling filter, harmonic calculation andcompensation function modules. On the basis of the hardware platform, debugthe program in CCS3.3, experimental results proved the correctness andfeasibility of the optimized hysteresis control method.