Research On High-Power-Factor Control Of The Converter Without DC-Link Electrolytic Capacitors For PMSM Drive

Variable-speed permanent magnet synchronous motor(PMSM) systems have been widely applied to home electrical appliances. In order to keep the DC-link voltage almost constant, the electrolytic capacitor with large capacitance is generally used in the DC-link, which results in low power factor, low reliability, high cost and large volume. Based on the background, focusing on PMSM drive systems without electrolytic capacitor, the profound analysis and study have been made in this dissertation to obtain high power factor.Compared to the PMSM drive system with large capacitance electrolytic capacitor, a small DC-link film capacitor is used in the PMSM drive system without electrolytic capacitor, which results in the different feature. Firstly, the PMSM mathematical model has been made, and the feature of the system without electrolytic capacitor has been analyzed and been compared with the traditional drive system. Then the vector control platform for PMSM drive systems without electrolytic capacitor is constructed. Secondly, the constraints of the PMSM operating and how to improve the power factor are investigated in detail. Based on the analysis, the current allocation strategy is designed for the purpose of high power factor. Thirdly, because the tradition PI controller can't track the fluctuating q-axis current reference with twice of AC source voltage frequency precisely, PIR controller and repetitive controller are designed and implemented as the current controller to obtain the precise tracking. Then the simulation platform is established in the Matlab/Simulink environment and the verification is realized by the simulation.At last, the hardware platform and the software design of the PMSM drive system without electrolytic capacitor based on vector control have been fully implemented based on Digital Signal Processor. A lot of experiment has been done to validate the designed control strategy for the purpose of high power factor. Experimental investigations show that the speed could be regulated well and the power factor could be improved effectively by the control strategy.