Design and implementation of a sensorless SRM drive with complete isolation

This paper presents a comprehensive sensorless method for controlling a 3 phase, 6/4 SRM with complete isolation. In this method the rotor position is achieved by processing the current results of injected high frequency diagnostic pulses to the motor windings. By finding the suitable pulse width at the beginning of the control algorithm and comparing the results, there is no need to consider any predefined threshold. This makes the proposed method highly independent of the SRM under test. Advancement of rotor excitation is done by control algorithm and increases rotor speed up to high speeds. The drive is designed without any common path between power and control circuits even with the presence of high frequency analogue signals. Finally, a position sensor is installed on the motor and the exciting pulses of stator windings are compared with the position sensor signals which demonstrate the correctness and precision of the method.