Analysis and Reduction of Electromagnetic Noise Induced by Dead Time Effect for an Axial-Flux Permanent Magnet Motor

This paper analyzes the influence of inverter dead time effect on the electromagnetic noise of axial flux permanent magnet (AFPM) motors. It is found that the 5th and 7th current harmonics induced by the dead time effect contribute the most to the increase of 0th spatial order electromagnetic force of the AFPM motor, thereby deteriorating its vibroacoustic performance. Then, by adding compensated switching time, a compensation method is used to reduce the output voltage errors of inverter. The simulation result validates the effectiveness of this dead time compensation method on the noise reduction of a 27-slot/30-pole AFPM motor. It is found that after compensation, the amplitude of the axial electromagnetic force drops by 70%, and its electromagnetic noise is reduced by over 6 dB(A). The noise prediction model used for simulation has been experimentally verified. This paper shows that dead time effect can increase the electromagnetic vibration and noise of AFPM motors and proper compensation methods will help mitigate this negative effect.