Induced Current Reduction in Position-Sensorless SRM Drives Using Pulse Injection

This article proposes a new pulse injection scheme for low-speed position-sensorless switched reluctance motor (SRM) drives with the reduced induced current. Conventional injection methods utilize a constant injection amplitude for position estimation; however, the induced current in idle phases nonlinearly varies with the rotor position and has significant magnitude. It results in large negative torque and degrades the control performance. To mitigate this problem, an injection amplitude regulator based on terminal sliding-mode control is put forward. The amplitude of pulse voltages is adjusted online through a nonlinear control law, and the induced current can be maintained at a minimal level over the whole idle-phase period. Moreover, the adverse impacts of motor parameter uncertainties are eliminated. As a result, the proposed scheme does not require SRM's magnetic characteristics and is easy to implement. The effectiveness was experimentally validated on a three-phase 128 SRM setup with comparisons of the conventional method.