Sensorless Adaptive Dwell Angle Control of SRM Drive for LEV Application

Abstract

In this work, switched reluctance motor (SRM) drive with a position sensorless approach is used for light electric vehicle. Sensorless control enhances reliability and reduces maintenance by eliminating position sensors, enabling compact, efficient, and high-torque drives suitable for urban transport, e-bikes, and small electric mobility platforms. For initial starting and acceleration of the vehicle, SRM is controlled at higher values of phase current and phase overlap conditions to achieve high torque. Flux-current-position polynomials are utilized for the detection of rotor positions. Commutation angles are made adaptive, through variation of turn-off and turn-on angles, for different operating conditions to get an improved performance. Active phase voltage and current are sensed to obtain flux and compared with flux values at known or required positions. Flux comparison and thus rotor position detection are executed only in specific regions. In these regions, phase flux has higher magnitudes flux lines are equally separated and spaced in flux-current-position characteristics. Thus, problems of identification and detection of rotor position, during low magnitude and dense flux detection, are taken care. Phase symmetricity property is utilized for flux detection and rotor position estimation in unaligned and aligned rotor positions, where flux lines are denser. SRM drive operates in regenerative braking mode to extend the vehicle's practical range by converting kinetic energy stored in vehicle's inertia back into electrical energy and returning it to power source. In this work, a 12/8, 1.25 kW, 28 A SRM is fed from an asymmetrical half-bridge converter, and a battery is connected to dc-link as a power source. Effectiveness of the presented algorithm is verified through experimental results.