Based on the fact that harmonic voltage and harmonic current will produce core loss and copper loss to reduce the operation efficiency in the direct torque control system of interior permanent magnet synchronous motor (IPMSM-DTC) for urban rail traction, efficiency optimization control strategy was presented based on switching frequency optimization. The adaptive hysteresis band value and optimized null vector distribution method were adopted to utilize the switching frequency of power device and optimize null vector to PWM. Efficiency optimization control system was implemented using a STM32F...