Abstract: Because of lower inductance and higher commutation frequency, caused by high-frequency current harmonics induced by the PWM control, super high speed permanent magnet brushless motors commonly face overheating of both the rotor and stator. For chopping directly at the inverter, the frequency should be increased to reduce the current harmonics. But for the 10 kW class motor drives used in the air compressors of fuel cell vehicles, the power switch devices currently do not fulfill the needs of switch frequency and power simultaneously. Therefore, it is not a good choice to regulate the speed by chopping at the inverter. Aimed at reducing losses in the stators and rotors, this paper presented the design of a pre-Buck square wave drive for reducing current harmonics. By optimizing the back electromotive force (EMF) filter circuit and commutation compensation angle, the operation range of sensorless control CAN was extended to 3000-100000 r·min^-1. The key points encountered during the drive development were analyzed and solutions proposed. Finally, the excellent performance of the drive was demonstrated by experiment.