Permanent Magnet Synchronous Motors (PMSM) have many advantages of small size, high power density and high efficiency. These advantages are responsible for its wide utilization with the rapid development of the power electronics technology and modern control theory. Direct torque control (DTC) of PMSM theory does not need rotating coordinate transformation, and has good dynamic performance. Thus, it has become a hot spot of academic research. Based on the traditional PMSM DTC theory, speed-loop control stra...