Magnetic Characteristics-less Position Sensorless Control of SRM drive for a Wide Speed Range for Light Electric Vehicle

This work presents an EV (Electric Vehicle) application-based magnetic characteristics-less position sensorless approach for the SRM (Switched Reluctance Motor) for for a wide speed range. A 3-phase, 48 V, 1.25 kW, 28 A, 12/8 SRM is controlled and driven through an asymmetric half-bridge (ASHB) converter for the required purpose. The aligned rotor position of each phase is identified with the inductance slope negative going instant. To avoid errors occurring because of the saturation and the switching of the phase, the demagnetization region in each conducting cycle is selected for the phase inductance measurement. The phase inductance slope is calculated through the sampled inductance and the sampling instants. The inductance slope variation is monitored and a flag signal is passed when the slope changes its sign. The turn-off angle of each phase is made adaptive in such a manner that there is an adequate amount of phase current for the inductance and the slope measurement at the aligned rotor position, without production of negative torque. The control algorithm allows the phase current to go beyond the rated value during starting and acceleration of the vehicle for the EV application. The rating of the machine is selected as per the light electric vehicle (LEV) specification.