| In recent years, with the wide use of power electronic devices and nonlinear loads,harmonic pollution in the power system is becoming more and more serious. Harmonicsuppression with reactive power compensation has become a major topic in the powersystem. Compared with passive filter, active power filter can not only suppress harmonicand compensate reactive power, but also is not affected by the impedance of the system. Itavoids the occurrence of harmonic amplification and resonance. Development trend ofactive power filter is modular. The modular of active power filter can realize theoptimization of heat dissipation and three-dimensional layout. The power density will beimproved and real-time compensation will be realized in function. Compensation effect isvery good.In this paper, the complete mathematical model of three-phase four-wire active powerfilter is established. Three-level structure is adopted in the main circuit. The space voltagevector modulation (SVPWM) method is used as the control method of active power filter.The control principle of SVPWM and the solution of mid-point voltage offset are mainlyelaborated in this paper. SVPWM algorithm is written in Matlab Fcn module to prepare forthe program transplantation in the DSP. Simulation results show that: For the balance andimbalance three-phase load the compensation effect is both satisfactory, and it has alsogood dynamic characteristics. The compensation control of three-phase four-wirethree-level active power filter is realized.Based on the theoretical analysis and Matlab/Simulink simulation, the softwareprogram of DSP is compiled and hardware circuit of active power filter is designed. Theminimum system board of TMS320F28335is adopted; current, voltage sampling circuit,zero voltage detection circuit, drive circuit based on the M57962AL and a variety ofprotection circuits are designed. Through continuous debugging of hardware and software,APF has good compensation effect. |
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