The Study Of Digital Control System Of Active Power Filter

Active power filter(APF) is an advanced power electronic device,which can be used for compensating harmonics,reactive power and negative sequence current. Compared with conventional compensation devices, active power filter has advantages of real-time and accuracy. So active power filter has been studied widely and is stepping into industrialization.The choice of its method of current detecting and control system are important factors that influence APF's performance. In this thesis, the requirements for real-time and accuracy of APF's control system were analyzed deeply. Based on the analysis, a simple, high efficient, digital real-time control scheme was brought forward, which foundation are Digital Signal Process(DSP) and Field Programmable Gate Array (FPGA) structure, as well as, its hardware platform was designed. In this thesis, assembler language was applied to program to realize DSP algorithm controller, which can perform such main computing as data collecting, self-adaptable distortion current detecting based on linear nerve cell, capacity voltage controlling in the side of direct current based on fuzzy control, PWM pulse width computing based on unsymmetrical rule sampling, etc. Quick control speed (one work period is 50μs) and high accurateness feature largely in the controller. In this thesis, VHDL hardware description language was applied to program FPGA to realize high accurate pulse generator. It can process dead-zone of two pulse signals accurately, whatever their types are, and has such characteristics as excellent performance, good flexibility and high reliability, and its switching frequency and dead-zone time are programmable. Therefore, the result can be applied to other power electronic devices such as transducer, SVG, etc.Lastly, APF's main circuit, snubber circuit and driver circuit were fixed, debugged, and improved in some aspects.