Robust speed control of a switched reluctance vector drive using variable structure approach

The robust speed control of a switched reluctance vector drive is presented in this paper. An approximate sliding-mode input power controller and another feedforward sliding-mode speed controller are combined with space voltage vector modulation. The resultant drive has rapid and robust speed response. In addition, a switched reluctance motor (SRM) drive incorporating the proposed controller requires only one current sensor and can be implemented in a low-cost 8-bit microcomputer and a few discrete integrated circuits. Furthermore, the controller does not require any offline characterization of the motor or load characteristics and could easily be applied to SRMs with any number of phase windings. A 4 kW four-phase SRM drive is constructed to test the performance of the controller. The results show that a step response from 200 to 1980 RPM needs only 2-3 s, even when driving a high-inertia load, and that the speed error can be controlled below 1%, even under unknown and dynamic loads. It is concluded that modified sliding-made controllers are effective in dealing with the highly-nonlinear characteristics of the SRM drive system.