A wide speed operation of SRM using low cost encoder

In switched reluctance motor (SRM) drives, the on-off angles of each phase switch should be accurately controlled in order to obtain the desired torque and speed stably. The accuracy of the switching angle is dependent upon the resolution of the encoder and the sampling period of the microprocessor. However, as the speed increases, the amount of the switching angle deviation from the preset values is also increased. Therefore, a low cost encoder suitable for the practical and stable SRM drive is proposed and a control algorithm using a simple digital logic circuit is also presented in this paper. As a result, a stable wide speed SRM drive can be achieved by the proposed high precision angle control. It is verified from experiments that the proposed encoder and logic controller can be powerful candidates for practical low cost SRM drives