Elimination of Current and Position Sensors in Switched Reluctance Motor Drives Using Direct Sensing of Leaking Flux

One of the primary challenges in widespread use of Switched Reluctance Motor (SRM) drives is the need to monitor rotor position for proper commutation of the stator phases. Additionally, the current magnitude in each phase must be measured and accurately controlled within a specific band. The sensors required to satisfy these functions are bulky, expensive, and prone to errors. Moreover, the position sensor, which is mounted on the shaft of the machine, reduces the compactness of the overall system. Rather than relying on current sensors for control or using complex methods to estimate rotor position, this paper presents a low-cost alternative that directly senses the leakage flux of the stator windings using Hall effect sensors that are mounted axially from the end wings of the stator. Each Hall effect sensor is positioned in front of one of the concentrated end windings of the stator phases. Since the sensed magnetic leakage flux offers a one-to-one correspondence with phase current and position of the rotor, a seamless control of the SRM is possible. The proposed control method is significantly more cost-effective, compact, and robust, enabling the development of a fully integrated inverter for SRMs. Additionally, the proposed method can detect the initial rotor position without requiring any extra devices, thereby providing a reliable startup process. Simulation and experimental results are provided to validate the claims.