A novel encoder for switching angle control of SRM

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position, because the position of rotor is an essential piece of information. Although high resolution optical encoders or resolvers are used to provide a precise position information, these sensors are expensive. Moreover, in the high-speed region, switching angles are fluctuate 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. 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.