A novel analog method for sensorless closed-loop control of SRM without parameter estimation

The stator winding current commutation with respect to rotor position is the central subject of switched reluctance motor (SRM) control. Therefore, detection of rotor position either directly or indirectly is essential for variable speed drive application. However, the use of a direct sensor is expensive and can be unreliable in some environments. This paper describes the development of a novel sensorless (both position and speed sensor) cost-effective general purpose analog controller without parameter estimation for closed-loop control of a 4-phase SRM for full speed range. The actual phase current signals are used for rotor position detection. Also the same phase currents are used for speed estimation, sequence locking and current limit for protection purpose.