Torque ripple minimisation of switched reluctance motor using sense coils

Abstract

Switched reluctance motor (SRM) offers several advantages compared to conventional motors such as low cost, rugged design and good high-speed performance. Torque ripple and the associated acoustic noise and vibrations have been a challenge for its application in low and medium power applications. The torque ripple is due to double salient structure and nonlinear magnetic characteristics of the machine. This study presents a sense coil system to measure instantaneous inductance that represents the non-linearity and saturation effects. The current profile is generated from the measured inductance to minimise the torque ripple and reduce the copper losses. The speed of motor is derived from the measured inductance thereby eliminating need for an external sensor. The effect of temperature and asymmetries in machine construction are compensated due to the dynamic nature of inductance measurement. The proposed method is implemented on a SoC FPGA to control the speed of SRM with reduced torque ripple.