Research On Proportional Resonance Control Strategy Based On DSP28335 Three-Level APF

With the rapid development of the society,the nonlinear load in the power system increases greatly.As one of the main power devices for harmonic control,active filter(APF)has become a research hotspot in the field of power electronics.Compared with two-level APF,three-level APF can withstand higher voltage,have lower harmonic distortion rate,lower switching frequency and smaller loss,and is more suitable for medium-high voltage and high-power fields.In this paper,a three-level APF based on DSP proportional resonance control strategy is designed.Firstly,the mathematical model of three-level APF in three-phase ABC coordinate system and rotating two-phase dq coordinate system is established,and its switching function is analyzed.Because three-level APF requires high computing speed and quick response of the system,the traditional SVPWM method cannot meet the actual needs.Therefore,SVPWM is improved to simplify the operation process effectively.The improved strategy determines the sector of the voltage vector according to the three-phase reference voltage.The action time of current operation is determined by means of shearing and integration.The switching time is determined by seven modulation modes.Therefore,the improved SVPWM is taken as the space vector modulation strategy in this paper.Secondly,the basic principle of proportional resonant current control strategy is studied,and a parallel current controller with multiple resonant controllers is designed.The impact response invariant method and the bilinear transformation method are used to program the PR controller.In order to solve the phase compensation problem,the zero phase of the controller is added.Thirdly,the simulation model is built on the MATLAB/Simulink platform.The three-level APF of the proportional resonance control strategy is simulated and analyzed,and the current waveform,voltage waveform and FFT distortion rate before and after the compensation of the traditional PI and PR control strategies are compared.Finally,the hardware platform is built,which is composed of DSP control board,sampling circuit,drive circuit and power circuit.The main chip DSP28335 is programmed and controlled by CCS software using C language to achieve the filtering and compensation effect.On this basis,the design of the software flow program and the establishment of the experimental platform were completed,and the experiment was analyzed and studied.