Thrust Ripple Rejection Of Pmlsm Based On Hybrid SVPWM

This thesis is supported by National Natural Science Foundation of China (51075281), and firstly summarizes the research status of permanent magnet linear synchronous motor (PMLSM) and direct thrust control technology. Direct thrust control of PMLSM has also been studied. The thesis also deeply analyzes control system performances. Based on MATLAB/Simulink simulation software, this thesis builds a simulation block diagram about direct thrust control system of PMLSM based on space vector pulse width modulation (SVPWM) and analyzes the simulation results. Simulation results show that the SVPWM method reduces the pulsations of thrust and flux to some extent. However, SVPWM method has dead zones. Therefore, the pulsations of thrust and flux are still large.This thesis analyzes the effect of SVPWM dead zones on the output voltage deeply. To further enhance the control precision of direct thrust control system and reduce the impact of dead zone compensation on controller, a new method is applied to direct thrust control system of PMLSM. This method avoids dead zone compensation and can modulate some voltage vectors with different directions and sizes to reduce thrust and flux pulse. In order to verify the feasibility of this method, this thesis carries out the simulation experiment of PMLSM direct thrust control based on hybrid SVPWM. Simulation results show that the method can effectively suppress thrust and flux ripples.Finally, the hybrid SVPWM method is implemented by TMS320F2812 DSP chip. The main work includes drawing flow charts, C language programming and application of VHDL for FPGA programming.Through simulation and experimental verification, this method can effectively suppress the ripples of thrust and flux and also makes the output current closer to the sinusoidal, which proves that the method for PMLSM direct thrust control system is feasible.