Study Of Direct Torque Control Of Permanent Magnet Synchronous Motor Applied In Electric Propulsion

With the development of the power semiconductor device, various advanced control strategies and microcontroller, alternating current (AC) drive technology plays the dominant role in the ship electrical propulsion systems. Controlling the electromagnetic torque directly in the AC speed system, the direct torque control (DTC) system has the excellent dynamic and static performance. And the digital signal processor (DSP) provides the stable material foundation for advanced controlling methods. This paper mainly introduces the study about the DTC system of permanent magnet synchronous motor (PMSM) applied in electric propulsion based.Firstly, this paper presents the mathematical model of PMSM in different reference frames and elaborates the DTC theory for PMSM. Secondly, based on the research on the traditional DTC system, the author of this paper presents an improved DTC method which adopts voltage space vectors subdivision and the multiple relay controllers. By making use of space vector pulse width modulation technique, this system can remain the switching frequency constant. And the simulation based on MATLAB/Simulink was carried out to study the performance of the new control system. The results of the simulation show that the introduction of improved DTC system is capable of effectively improving the steady state performance and keeping the excellent dynamic performance of the PMSM DTC system simultaneously. The simulation is very important for the development of DTC of PMSM. At last, according to the theory analysis of the PMSM DTC system, the hardware of the speed control system was designed and the software was compiled.In this paper, the author studied DTC of PMSM applied in electric propulsion based on DSP and combined the control theory and the real character of the motor to build up the valuable control system.