| || Impact of Dwell Angle on the Electromagnetic Torque Ripples of the Switched Reluctance Motor
Author : Bhuvaneswari, G.;Srinivasa Rao, P.;Thakurta, Sarit Guha;Murthy, S. S.
Source : Defence Science Journal ; Vol:58(3) ; 2008 ; pp 363-371
Subject : 53 Applied Physics;532.542 Fluid Dynamics
Keywords : Commutation;Dwell angle;Sensor-less control;Switched reluctance motor;SRM;Electromagnetic torque
Abstract : Switched reluctance motors (SRM) are emerging as promising competitors to the vectorcontrolled induction motor (VCIM) drives and permanent magnet (PM) motor drives in the variablespeed drive market owing to their robust nature coupled with low cost, simplicity, and capability to operate in harsh environments. They are also suitable for nuclear and aerospace applications due to their low inertia and capability to be fed from a dc supply through a simple power converter. The principle of torque production in SRM makes rotor position information mandatory for effective control of the drive. The torque produced by any particular phase of the SRM is dependent upon the exciting current and the period during which the current is carried by that phase winding. The conduction period of any particular phase is termed as dwell angle when it is specified in terms of rotor angular position. In the present work, the SRM operation has been analysed in sensor mode and in sensor-less mode, paying special attention to the relationship between dwell angle and output torque ripple. The performance has been studied for different values of dwell angle and the resultant torque profile has been analysed. From the analysis, a methodology has been devised to deduce an appropriate value of dwell angle for minimising the torque pulsations, given the values of speed and load torque, thus improving the performance of the SRM drive.