Loss Minimization Control of Aircraft Wound-Rotor Synchronous Starter–Generator in the Starting Mode

The wound-rotor synchronous machine has become a competitive candidate for the integrated starter–generator of more electric aircraft. Due to the large inertia of aircraft engine, the armature currents of the main machine (MM) are large and the windings heat up severely. In order to reduce the heat generation during the starting process, it is necessary to research a loss minimization control method of the wound-rotor synchronous machine in the starting mode. Based on the equivalent circuits considering the equivalent iron loss resistance, this article derives the controllable electrical loss function of the MM. Since its field current changes with speed, the derivative term of the field current with respect to time is considered. By solving for the extremum, the reference value for the d-axis current of the minimum loss point is derived and a loss minimization control method for the MM in the starting mode is proposed. Besides, based on the model reference adaptive system, an adaptive law is designed to identify the stator resistance, thereby improving the accuracy of the loss minimization control method. Experiment results show that the proposed method can effectively reduce the controllable electric loss and thus suppress the heat generation during the starting process.

I. Introduction

The integrated starter–generator (ISG) system is a significant technology for more electric aircraft. Wound-rotor synchronous machine is widely used as the generator in the aviation ac power system, and it has become a competitive candidate for aircraft ISG because of high reliability, mature structure, and generation technologies [1], [2]. On the basis of achieving the starting function of the wound-rotor synchronous starter–generator (WRSSG), some researches on rotor position estimation and fault diagnosis for rotating rectifiers have been carried out [3], [4] and enriched the control strategies of WRSSG [5].