Acoustic noise reduction of a 6/4 SRM drive based on third harmonic real power cancellation and mutual coupling flux enhancement

In this paper, an effective technology is presented for noise reduction and torque increase in a three-phase 6/4 switched reluctance motor (SRM) drive without position sensors. Using a three-phase full bridge inverter and Y-typed connection of winding configuration, three-phase sinusoidal currents in each commutation region can be controlled to form long and short-flux paths. Long main flux can be added by short mutual coupling flux to enhance the stator flux; the resulting current-oriented control scheme can obtain a higher electromagnetic torque and cancel the third harmonic real power. To verify the effectiveness of the proposed scheme, it was applied to a 350 W three-phase 6/4 SRM drive system operating below 1500 rpm. Experimental results yield maximal acoustic noise at 74 dB and maximal torque at 21 kg cm. Moreover, the 6th harmonic real power is found to be the dominant source of acoustic noises in the SRM system.