A Sensorless Control Strategy of Permanent Magnet Starter/Generator under All Working Conditions

With the advantages of high-power density and simple control, permanent magnet starter/generator (PMSSG) is a better choice over other types of starter/generators in small and medium-sized aircraft. However, position sensors are susceptible to interference due to the complexity of operating conditions. Therefore, a sensorless control strategy for PMSSG under all working conditions is presented. Firstly, a double-closed-loop switch control strategy is designed for starting and power generation conditions. Then, the working area of the sensorless method is divided according to the speed, and the high-frequency injection method is used to obtain the rotor position information in the low-speed range. To weaken the chattering of traditional sliding mode observers, a fractional sliding mode observer is designed in the high-speed range for sensorless control. The simulation results show that the above control strategy can achieve accurate rotor position estimation under all working conditions.