A control scheme for a High Speed Railway traction system based on high power PMSM

The high power permanent magnet (PM) traction drive has recently been highlighted due to its promising qualities such as high efficiency and power density. For better performance, a robust, efficient and reliable control and driving scheme needs to be designed. In this Paper a control scheme is designed which based on Most Torque Per Ampere (MTPA) strategy to obtain high power density and is specially designed to achieve smooth transition between constant torque mode and constant power (field weakening) mode. In addition, a novel low-frequency pulse width modulation (PWM) scheme is designed to achieve smooth transitions between various fundamental-carrier wave frequency ratios while maintaining the synchronization between stator and rotor flux throughout the entire operation range. The validity of the scheme has been proved by simulation results and experiment is underway.