Motor Carrier Electromagnetic Noise Caused by PWM Pulse Modifying Technique of DC Bus Current Detection

This paper describes the carrier electromagnetic noise caused by PWM pulse modifying technique of DC bus current detection. It is cleared from theoretical analysis that the influence factors of carrier harmonics are DC voltage, self-inductance and pulse modifying width. As estimated the carrier electromagnetic noise, we propose the new evaluation index of radiation area electromagnetic force to multiply the radial electromagnetic force and gap surface area. The proposed evaluation index can be estimated the increase of carrier electromagnetic noise within 1.5dB error by experiment. Also, the one phase pulse modifying method to reduce the carrier electromagnetic noise is proposed. The effect of this method was demonstrated in the experiment.