Switching Frequency Optimize and Fuzzy Logic Based Direct Torque Control of Permanent Magnetic Synchronous Motor

The relation among motor speed, torque hysteresis band width and switching frequency was analyzed, and switching frequency optimize means was proposed. In order to improve the system stability and raise the response speed, fuzzy logic based direct torque control for a permanent magnet synchronous motor (PMSM) was put forward. In this scheme, zero voltage space vectors are introduced to simplify fuzzy control rulers. Simulation results show that the flux locus of the fuzzy direct torque control is more approximatively a circle by switching frequency optimize and fuzzy control, and the rotational speed can reach up to as table value quickly and the torque for the proposed scheme can change smoothly.