Computation of torque pulsations of switched reluctance drive

The switched reluctance (SR) drive exhibits torque pulsations (ripple) due to: (i) the constructional features of the machine-salient poles on both stator and rotor; and (ii) a switched form of supply. The form and level of torque pulsations are therefore dependent on variables related to the geometrical form of the magnetic circuit and on those related to the phase current waveform. The influence of these variables on torque pulsations can be estimated by sophisticated mathematical models. The authors describe a procedure for computing the instantaneous values of electromagnetic torque exhibiting pulsations. It is assumed that magnetic parameter data (inductances or flux-linkage against position and current) are known, i.e. the data are obtained by measurements in stall conditions or computed by numerical field analysis.