Research on direct torque control of permanent magnet synchronous motor based on optimized state selector

This paper describes an investigation of optimized state selector method of DTC for permanent magnet synchronous motor (PMSM) drives. The increase of electromagnetic torque of PMSM is proportional to the sine of the angle between the stator and rotor flux linkages and therefore fast torque response can be obtained by increasing the rotating speed of the stator flux linkage as fast as possible. In conventional direct torque control (DTC), there are partitioned six sectors in the stationary two-axes reference frame and vectors of stator flux linkage is controlled by selecting different vectors of six voltage vectors. But there are questions in this control method. When stator flux linkage is especially in the adjacent region of two sectors and the amplitude of stator flux linkage is easily fluctuating and more the voltage vector which should be selected is also uncertainty. The presented control strategy of optimized state selector DTC method is aimed at the actual questions of all above. The paper discusses the scheme of optimized state selector DTC and the control system structure of it in details. At last, Simulation results well demonstrate the effectiveness of the proposed control method in comparison with conventional DTC method in some aspects.