起动/发电（S/G）系统作为多电飞机（MEA）的核心动力来源，既可实现带动航空发动机起动点火的功能，也可以由发动机拖动发电，为整机提供电能，具有集成度高、效率高等优点。本文主要对高开关频率大容量三电平变换器和基于高速永磁同步电机（PMSM）的起/发系统进行了研究，主要内容包括：本文首先对高开关频率大容量三电平中性点箝位（NPC）变换器展开研究。通过分析两种不同的NPC电路拓扑结构及不同的调制方法，从谐波特性、系统效率及损耗均衡、电压应力及高杂散参数下缓冲吸收电路的设计、中性点电容电压平衡控制能力等方面比较了不同方法在起/发系统中应用的优势和劣势，得出了有源中性点箝位载波层叠(ANPC-PDPWM）方法具有显著优势的结论。针对加入缓冲吸收电路后吸收电容与杂散电感的谐振问题，提出了一种改进的ANPC调制方法，能够有效地抑制谐振，该方法通过仿真和实验得到了验证。其次，本文分析了PMSM的数学模型，并在此基础上研究了起/发系统中PMSM的起动控制策略。起动过程可以分为恒转矩起动和恒功率起动两个阶段。考虑到基于数字控制的电机控制系统由于采样、计算以及调制等原因存在控制滞后问题，研究了相应的滞后补偿算法并对算法的稳定性进行了分析，仿真结果验证了理论分析的准确性。PMSM无速度传感器控制也是本文的研究重点，针对基于模型参考自适应（MRAS）方法的PMSM无速度传感器控制，分析了由于数字控制引入的位置估计误差，提出了一种消除稳态和暂态位置估计误差的方法，仿真和实验验证了提出的补偿方法的可行性。最后，分析了基于电压或电流闭环控制的PMSM发电系统的数学模型。为了实现发电过程中高转速下母线电压的可控，需要对PMSM进行弱磁控制。本文使用了基于电压反馈的弱磁控制方法，通过仿真和实验验证了提出控制策略的可行性。对于多台发电机并联运行的系统，分析了主从控制和下垂控制两种方法。下垂控制中直流母线电压随功率的变化而变化，不能控制为恒定值。为解决这一问题，本文提出了一种下垂控制补偿控制方法，可维持稳态电压的恒定。除此之外，本文还建立了永磁同步发电系统的小信号模型，通过阻抗分析的方法分析了影响系统稳定的关键因素，对系统的设计及控制参数的选取具有参考意义。
As the major power supply of more electric aircraft (MEA), starter/generator (S/G) system can not only realize the function of driving the aero-engine to its ignition speed, but also can be driven by the engine to generate electrical power for the entire aircraft. Hence, it has the advantages of high integration and high efficiency. In this paper, the high-power high-frequency converter and the S/G system based on high-speed permanent magnet synchronous machine (PMSM) are studied. The main contents are as follows:Firstly, a high-power abd high-frequency three-level neutral point clamped (NPC) converter is developed. By analyzing the two different NPC circuits topologies and various modulation methods, the advantages and disadvantages of the different methods in S/G system are compared from the aspects of harmonic characteristic, system efficiency and loss balancing, voltage stress and design of snubber absorption circuit, ability of capacitor voltage balancing control of the neutral point, and the conclusion is drawn that the active neutral point clamped phase disposition pulse width modulation (ANPC-PDPWM) method has significant advantages in S/G system. In additional, an improved ANPC modulation method is proposed to suppress the resonance of stray inductor and absorption capacitor after adding snubber absorption circuit to the ANPC converter. It has been verified by simulation and experiment.What’s more, the mathematical model of PMSM is analyzed, and the startup control strategy of PMSM in S/G system is studied. Starting process can be divided into two parts: constant torque control (CTC) and constant power control (CPC). Considering that the motor control system based on digital control has a lag problem due to the process of sampling, calculation and PWM modulation, this paper studies the corresponding compensation algorithm and analyses the stability of the strategy. The digital simulation results verify the correctness and accuracy of the stability analysis. As for the speed sensorless control based on model refrences adaptive system (MRAS), this paper also analyses the position estimated error introduced by digital control, and proposes a method to eliminate both steady and transient position error. It is verified by simulation and experiment.Finally, the mathematical model of generator system based on voltage or current closed-loop control is analyzed. In order to control the bus voltage stability at high speed in generator mode, the flux-weakening control is introduced. In this paper, a flux-weakening control based on PI controller is applied. The feasibility of the proposed control strategy is verified by MATLAB simulation and experiment. For the generators parallel operation system, this paper also analyses two methods, includes master-slave control and droop control, and puts forward a control method which can compensate for the reduction voltage of droop control. In addition, the small signal model of permanent magnet synchronous power generator system is established. The key factors affecting the stability of the system are analyzed by impedance analysis and they are verified by simulation.
