Novel encoder for switching angle control of SRM

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with rotor position because the position of the rotor is an essential information. Although high-resolution optical encoders or resolvers are used to provide precise position information, these sensors are expensive. Moreover, in a high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low-cost analog encoder suitable for practical applications is proposed. In addition, the control algorithm to generate switching signals using a simple digital logic is presented. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.