Wound-field synchronous machine has become an important candidate for the integrated stator-generator of more-electric aircraft. The aviation power system requires the wound-rotor synchronous starter-generator to have the ability of three consecutive starts. The large amount of heat generated during the starting process will increase the difficulty of the second and third starts. Therefore, it is of great significance to research maximum torque per ampere (MTPA) methods that can reduce the stator copper loss of the main machine. Traditional MTPA control method ignores iron loss, which lead to errors of MTPA point. This paper proposes a virtual high-frequency signal injection based MTPA method considering iron loss. Simulation and experimental results have verified the effectiveness of the proposed MTPA method.

Accurate rotor position estimation plays an important role in the start control for the aircraft three-stage Wound Rotor Synchronous Starter-Generator (WRSSG). In this paper, a novel exciter controller and rotor position estimation method for aircraft WRSSG were proposed. The exciter controller consists of a three-phase full-bridge converter and a full H-bridge converter, and it is used to inject high frequency voltage into the permanent magnet pre-exciter to estimate the rotor position in the starting mode, and regulate the field current of the main exciter to control the output voltage of the main machine in the generation mode. The proposed rotor position estimation method has the advantages of high stability and high estimation accuracy. Simulation analysis verified the feasibility and effectiveness of the proposed exciter controller and rotor position estimation method.

For sensorless starting control of the brushless synchronous starter/generator (BSSG), signal injection is commonly adopted to estimate the initial rotor position of the main generator (MG). Due to the special structure of BSSG, signal transmission link between MG and the main exciter (ME) is a rotating rectifier that has a complicated operating principle. The lack of theoretical analysis of this complex transmission path leads to unreliability and inaccuracy for the methods based on it. In this paper, the transmission mechanism of injected signals from the field winding of MG to the stator windings of ME is clarified. According to this theory, a novel initial rotor position estimation method of MG is proposed. Both the simulation and experiment results show that this approach can provide initial rotor position of MG with reasonable accuracy.

The cross-coupling effect is the most common phenomenon in the electric machinery operation, it has the influence on the machine efficiency and control scheme. However, the cross-coupling effect is ignored in the existing virtual signal injection (VSI) maximum torque per ampere (MTPA) control. In this paper, the online searching MTPA control based on VSI scheme for Integrated Starter/Generator (ISG) system considering the cross-coupling effects is proposed. For obtaining the accurate torque gradient with respect to the torque angle online, the torque equation in the existing VSI scheme is extended by the cross-coupling effect is proposed. A prototype is set up and experiments are carried out to verify effectiveness the proposed control scheme.

A novel failure detection method for rotating rectifier of the brushless synchronous starter/generator in the generator mode has been proposed. In this method, the terminal voltage of the idle field winding of the main exciter is used. Firstly, the first maximum voltage and corresponding position in the voltage sample sequence are obtained. On this basis, the voltage sample sequence is reconstructed into two sequences to acquire the second maximum voltage. Then the voltage ratio is calculated for failure detection. Experimental results verify the feasibility and effectiveness of the proposed method.

The rotating rectifier in the brushless synchronous starter/generator is more vulnerable than others. Therefore, fault detection of the rotating rectifier is necessary. This article focuses on the identification of the diode failures in the rotating rectifier of the brushless synchronous starter/generator. Traditional approaches based on the analysis from the main exciter field current or main machine output voltage may lose the fault location information. To solve this problem, the fault features based on the rotor current are analyzed. With a simple rotor current restructuring approach, the magnitude ratio of second harmonic to fundamental obtained by bandpass filters on the restructured rotor current is employed to confirm the one diode open-circuit or one diode short-circuit fault. The experimental results verify the feasibility and effectiveness of the proposed method.

This study focuses on the identification of the phase-to-phase short-circuit fault and phase open-circuit in the exciter rotor windings of the brushless synchronous starter/generator. Traditional methods are based on the analysis that the faulty rotor currents have effects on the stator winding currents or voltages, but these approaches will lose the fault location information. To locate the fault phase, the restructured rotor current by the exciter stator voltage, current and rotor position are employed. Then the root mean square (RMS) value and the third harmonic of the restructured rotor current is used for fault detection and location. The experimental results verify the feasibility and effectiveness of the proposed method.