Direct Torque Controller for Switched Reluctance Motor Drive using Sliding Mode Control

A direct torque control algorithm for switched reluctance motor (SRM), using sliding mode control (SMC), is reported in this paper. SRM magnetization characteristics is highly non-linear, where torque is a complex and coupled function of phase current and rotor position. Finding equivalent current reference for a given torque reference becomes non-trivial. In order to avoid this conversion, a direct torque control strategy is used. As it is difficult to develop an accurate non-linear model for SRM, the torque controller should be robust to model inaccuracies. It is well known that SMC provides robustness to such model uncertainty. By exploiting this property of SMC, a simplified trapezoidal phase inductance profile is used to obtain an equivalent control. For robustness, a saturated switching control is added to the equivalent control. The resulting controller keeps torque tracking error within a narrow band near zero, and there by minimizes torque ripples. Experimental results from a 1-hp, 4-phase SRM are provided, which demonstrate the effectiveness of the proposed torque control scheme.