A position sensorless hybrid control method for electrically excited synchronous motor

Electrically excited synchronous motors have the advantages of wide speed range, high overload capacity, and adjustable power factor, and are widely used in high-power transmission fields, where position sensorless control technology is an important part of the speed regulation of electrically excited synchronous motors. A back-to-back voltage-source converter structure, current frequency control, sliding mode observer, and Kalman filter are presented, followed by two position sensorless control schemes using only current frequency control and hybrid control combining current frequency control and sliding mode observer. Simulation and experimental results verify that both control schemes can achieve variable frequency starting and speed regulation of electrically excited synchronous motors without position sensors, but the hybrid control scheme combining current frequency control and sliding mode observer has the advantages of high-power factor and high practicality, and is more suitable for high-power drive applications.