Dual-Machine Injection Method-Based Sensorless Starting Strategy for Wound-Rotor Synchronous Starter/Generator

Wound-rotor synchronous starter/generator (WRSSG) has been widely adopted in the modern aircraft. The uncertainty of the inductive saliency in WRSSG (the saliency may change, disappear, or reverse during starting process) makes it difficult to implement the sensorless starting in the low speed region. This paper proposes a dual-machine injection method for the sensorless control of WRSSG, which is able to eliminate the dependency on the machine saliency in rotor position estimation. Using the multi-stage structure of WRSSG, in the proposed method, a high frequency (HF) voltage is injected in the main machine (MM) of WRSSG, and HF current response in the main exciter (ME) side of WRSSG is detected and used to estimate the rotor position since the ME is connected with the MM through a rotating rectifier. Experiments about the proposed dual-machine injection method on a WRSSG prototype in low speed region are carried out, and the experimental results verify the effectiveness and advantages of the proposed method.

I. Introduction

Wound-Rotor synchronous starter/generator (WRSSG) has been widely used as the generator in the aircraft power system. Integrated starter generator (ISG) system removes the special starter and uses WRSSG as the motor to start the aero engine in the starting mode [1]–[4]. The control of WRSSG in starting process requires the rotor position to generate the required torque. In traditional ISG system, the mechanical position sensor increases the size and decreases the reliability. Hence, the sensorless control techniques of WRSSG have been investigated in the past few years [5], [6].