Torque-Enhanced Phase Current Detection Schemes for Multiphase Switched Reluctance Motors with Reduced Sensors

Abstract

An n/2-sensor-based and an (m + 1)/2-sensor-based phase current detection scheme are proposed for even-numbered switched reluctance motors (EMSRMs) with n phases and odd-numbered switched reluctance motors (OMSRMs) with m phases. For the EMSRMs, the phases are divided into n/2 groups each of which includes two phases furthest from each other, and the lower dc bus is split into n/2 + 1 buses such that the currents through the lower switches of a group flow through a bus whose current is detected by a sensor. For the OMSRMs, the phases are divided into (m + 1)/2 groups and the currents through the lower switches of a group are detected by a multiplexed sensor without converter modification; the phase grouping is generalized as an optimization problem considering the volume and measuring range of the sensors. The schemes can detect the magnetization and freewheeling phase currents under multiphase excitation without pulse injection and voltage penalty. Compared to the existing schemes using cross-winding sensors, the proposed schemes can increase the motor torque by extending the phase conduction region. In addition, the proposed scheme for EMSRMs can combine the low-cost low-side shunt current sensing technique, and the proposed scheme for OMSRMs can increase the current sensing resolution. Simulations are carried out to validate the two proposed schemes. The proposed (m + 1)/2-sensor-based scheme is further verified experimentally.