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.

Aiming at the aircraft two-stage high-voltage direct current (HVDC) integrated starter-generator (ISG) system, this paper proposes a control method for armature current minimization and stabilized power generation based on PWM rectification and excitation regulation. Based on the structural principle and mathematical model of the two-stage HVDC ISG system, the optimization problem of armature current minimization is analyzed and solved from a mathematical point of view, and then the control method of the minimum armature current of the main machine (MM) in the wide-speed range power generation state is derived. The proposed method can realize fast dynamic response performance while keeping the armature current minimized in a wide speed range for the two-stage HVDC ISG, which is of great significance for reducing the stator copper loss and the burden of rectified power devices of the system. Finally, the feasibility and effectiveness of the proposed method are verified by simulation and comparative analysis.

In this paper, an accurate and timely fault diagnosis method for exciter rotor windings of the wound-rotor synchronous starter-generator (WRRSG) is proposed. Traditional methods are mostly based on the estimation of the rotor current, and cannot detect the fault in both start-up and generation modes. To overcome these difficulties, the proposed method uses the sum of squared stator currents of the main exciter (ME) as the fault information. The ratio of the two adjacent maximum peaks of the fault information is calculated and used in fault detection. Then, the corresponding rotor position where the maximum peak of the fault information occurs is collected to determine the fault location. The experimental results verify the feasibility and effectiveness of the proposed method.

Due to the use of feedback excitation method in the two-stage integrated starter-generator system (TISGS), the output voltage of the main machine (MM) is prone to fluctuations, and when the system is suddenly loaded, the output voltage will drop sharply or even cause a voltage crash, so the anti-disturbance capability of the system is crucial. Since the traditional PID control method is based on the error to generate a control strategy to eliminate the error, it can meet the control requirements of the output voltage loop, but it is difficult to meet the high-performance requirements of the excitation current loop. Therefore, this paper proposes a method to use the active disturbance rejection control (ADRC) instead of the PID to control the excitation current of the brushless exciter (BE). In this method, the ADRC controller of the excitation current and the PID controller of the MM output voltage are combined to form a dual closed-loop controller, so as to realize the voltage-stabilizing control of the system. The simulation results verify that compared with the traditional double-closed-loop PID control method, the proposed method can improve the anti-disturbance capability of the system and suppress the fluctuation of the output voltage.

The existing rotor position estimation methods for aviation brushless synchronous starter/generator (BSSG) are with such drawbacks as the complex signal processing and phase delay caused by filters. In this paper, by analyzing rotor current characteristics of main exciter (ME), a novel rotor position estimation method based on “fixed-point sampling on rotor's direct-axis current of ME” used for main machine (MM) is proposed. The method is implemented by three steps: Firstly, rotor's direct and quadrature axis currents of ME is calculated by ME's stator voltage and current signals; Secondly, through fixed-point sampling on the calculated direct-axis current, and performing simple mathematical operations on sampled values, the sine and cosine information containing ME's rotor position information can be extracted, further, phase-locked loop is used to extract ME's rotor position; Finally, based on the structural characteristics of BSSG, rotor position increment of MM can be obtained, and combining MM's initial rotor position, MM's real-time rotor position is obtained to realize sensorless starting control of BSSG. The method avoids high-frequency signal injection and using of filters, and is without influence by MM's operating state and saliency variation. Experiment verifies the effectiveness and high accuracy of the proposed method.

The traditional rotor position estimation method of permanent magnet synchronous motor at zero and low speed based on high-frequency pulse voltage signal injection inevitably adopts band-pass and low-pass filters, which reduces the dynamic response speed of the system. In this paper, a new rotor position estimation strategy is proposed. First, in the static coordinate system, the pulse vibration high-frequency signal with the same frequency and amplitude is injected into the α and β axis respectively. At the same time, the DC offset for rotor position estimation is extracted. Then the high-frequency pulse vibration signal is injected into the α axis, the obtained DC offset is used to compensate the current response signal, and the cascade filter is used to expand the bandwidth of the position estimation link and improve the dynamic response; Finally, at zero speed, the positive and negative square wave signals are injected into the α axis or β axis, and the initial position is determined by comparing the current amplitude of the corresponding shaft. The effectiveness of this method is verified by simulation. The results show that this method can quickly and accurately obtain the rotor position information at zero and low speed, and has good stability and dynamic characteristics.

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.

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.

The paper proposes an alternative method to design two-phase exciter based on the existing single-phase exciter to solve the excitation problem for the main generator when the aircraft starter/generator starts up. Compared with distributed winding, concentrated winding has been adopted for the exciter's field winding for the advantages of shorter end-windings and available space for air duct in the stator which really meet the demand of aircraft machines on volume and heat dissipation. Initially a reconfiguration of the existing single-phase exciter into a two-phase exciter has been carried out to assess the potential of the existing exciter. The relationship between the number of the field winding's turns of single-phase exciter and two-phase exciter has been analyzed, on the basis of which electromagnetic design has been accomplished using FEA. Simulation results verify the reasonability of the analysis and confirm that the two-phase exciter is capable of generating the required current both in the start and generation modes. Finally, the characterization of the two-phase exciter has been studied to supply excitation control with theoretical support.