Research Of AC Permanent Magnet Synchronous Motor’s Direct Torque Control

Permanent magnet synchronous motor is mainly used in variable speed drive and servo control. It has drawn increasing attention because of a series of advantages such as small size, light weight, wide speed range and high power density. Direct Torque Control is gaining more and more applications in the AC motor control principle with its advantages such as simple structure, fast torque response and easy to realize the digital control as an advanced AC motor control principle. The direct torque control in Permanent magnet synchronous motor has become the research in the field of AC drive because of their outstanding features,In this paper, Conventional permanent magnet synchronous motor direct torque control has been researched and implemented based on the theory of Direct Torque Control. The results show that the system has good control performance and closed-loop parameters have impact on the system. Conventional permanent magnet synchronous motor direct torque control system has two major flaws which large flux and electromagnetic torque ripple and the inconstant of Inverter switching frequency. Space vector modulation and fuzzy logic are applied in conventional permanent magnet synchronous motor direct torque control system to Improve inadequate of Conventional permanent magnet synchronous motor direct torque control system. The simulation results show that PMSM direct torque control system which is based on fuzzy logic is good for the suppression of flux and torque ripple. However, it has less effective in Relative space vector modulation. Space Vector Modulation permanent magnet synchronous motor direct torque control system can not only improve Flux torque ripple, but also overcome the shortcomings of conventional direct torque control system that the switching frequency is not fixed. For the electromagnetic torque response speed Conventional permanent magnet synchronous motor direct torque control system responds fastest, the Permanent Magnet Synchronous Motor direct torque control system based on fuzzy logic follow by it, and Permanent Magnet Synchronous Motor Direct Torque Control System based on Space Vector Modulation is slowest.The estimation accuracy of speed and stator flux directly affects the performance of permanent magnet synchronous motor control, Though this way can obtain the estimation of speed by mechanical sensor directly in Conventional permanent magnet synchronous motor direct torque control system, the system cost increases and its application in harsh environments is limited. No sensor technology used in permanent magnet synchronous motor direct torque control system to achieve the speed and stator flux estimate online real and solves the problems mechanical sensors and the stator flux caused by inaccurate estimation. A high performance senseless permanent magnet synchronous motor direct torque control system is established. The system realizes the online real-time observation permanent magnet synchronies’motor stator flux, speed, and rotor position angle by the extended Kaman filter. An improved method of extended Kalman filter speed estimation based on particle swarm optimization has been proposed to to solve problem that the extended Kalman filter cannot accurately obtain in speed estimation. This method combines the advantages of PSO algorithm and genetic algorithm. The simulation results show that improved PSO can find better solutions more quickly in optimizing extended Kalman filter comparing with genetic algorithms and particle swarm optimization.