The Research On System Of Permanent Magnet Synchronous Motor Variable Frequency Speed Adjusting

Based on the operation theory of the Permanent magnet synchronous motor (PMSM) the details of the variable frequency speed adjusting theory of PMSM is presented in this paper together with the field-orientation vector control (VC) system of PMSM based on DSP. PMSM has the advantage of smaller volume, higher efficiency and power density over the induction motor. Therefore the research on PMSM has entered a new stage since the 1980' s with the improvement of ratio between the performance and the price of the PM material and the development of the power electronics devices. PMSM has its own characteristics compared to the induction motor and the EESM. Naturally the paper originates from the PMSM itself, discusses the steady operation theory, analyses the torque character of PMSM, power character and efficiency as well. VC theory is one of the greatest breakthroughs in the AC speed control field. Also details of the VC of PMSM is presented in the paper, and the analysis of several circuit control strategies of VC theory applied to the PMSM control, which include the id =0 control, cos = 1 control and the max torque/current control. A complete digital PMSM VC system based on DSP is developed with the soft and hard ware design plans given. The paper discusses the theory of weaking flux speed control of PMSM and the reason why the weaking flux speed extending is difficult, and then brings out two new weaking flux plans, which have special rotor structures. Direct torque control (DTC) theory is another advanced control theory after VC theory in the speed control field. The application of DTC theory on PMSM is discusses in the end and the simulation results show perfect dynamic performance, minor static error and good robustness characteristic.