永磁无刷直流电机系统转矩波动抑制与调制策略研究

发布时间：2018-01-12 14:45

本文关键词：永磁无刷直流电机系统转矩波动抑制与调制策略研究　出处：《天津大学》2014年博士论文　论文类型：学位论文

【摘要】：永磁无刷直流电机由于具有功率密度大、效率高、体积小等优点，被广泛应用于航天航空、军事装备、工业自动化等领域。本文围绕永磁无刷直流电机系统高效能、低成本、高可靠性等工业应用中的实际问题，对永磁无刷直流电机系统控制策略、调制方法以及新型逆变器拓扑结构展开研究。针对永磁无刷直流电机系统反电势和电流换相引起的转矩波动问题，研究了转矩波动产生机理，研究了不同开关调制策略对控制器带宽的影响规律，建立了电机在非换相运行过程和换相运行过程中转矩与电流的映射关系，提出了电流优化控制策略。该策略利用线反电动势波形分别优化电机非换相运行过程和换相运行过程中控制系统的参考电流，，以抑制反电动势对转矩的影响。在换相运行过程中，根据不同的转速区间，分别采用低速换相调制策略和高速换相调制策略，实现了非换相绕组电流对参考电流的准确跟踪，抑制了换相转矩波动。设计了积分变结构电流控制器，通过合理设计控制器连续分量，使开关分量的开关增益仅依赖于参数扰动和系统不确定性扰动，有效地减小了开关分量引起的系统抖振。针对三相四开关永磁无刷直流电机系统中反电动势引起的电流畸变问题，建立了非导通相反电动势和电流之间的映射方程，分析了不同调节矢量对非导通相电流的调节机制，提出了三有效矢量调制策略和两有效矢量调制策略。两种调制策略利用调节矢量对非导通相电流的不同调节机制，抑制反电动势对电流的负面影响，并控制非导通相电流的平均值收敛于零，有效提高电流动态和稳态性能。本文构造Lyapunov函数以证明两种调制策略的稳定性，并基于稳定性判据采用简单的方法计算调节矢量的占空比。针对永磁无刷直流电机系统在低压场合带载能力和调速范围受限制的问题，研究了三相四开关逆变器和升压变换器的运行特性，将二者有机结合，提出了升压型三相五开关逆变器拓扑结构和升压三有效矢量调制策略，该策略利用直通矢量对输出电压的调节机制，实现了电机系统升压功能，有效拓展了永磁无刷直流电机在低压场合的带载能力和调速范围。通过搭建硬件实验平台，对提出的电流优化转矩波动抑制策略、三有效矢量调制、两有效矢量调制策略以及升压型三相五开关逆变器拓扑结构进行了实验验证，实验结果证明了理论分析的正确性和提出策略的有效性。
[Abstract]:Permanent magnet brushless DC motor is widely used in aerospace and military equipment because of its high power density, high efficiency and small size. This paper focuses on the practical problems of high efficiency, low cost and high reliability in industrial application of permanent magnet brushless DC motor system, and the control strategy of permanent magnet brushless DC motor system. The modulation method and the new inverter topology are studied. Aiming at the torque ripple caused by reverse EMF and current commutation in permanent magnet brushless DC motor system, the mechanism of torque ripple is studied, and the influence of different switching modulation strategies on the controller bandwidth is studied. The mapping relationship between torque and current in non-commutative operation and commutation operation is established. A current optimal control strategy is proposed, in which the reference current of the control system during the non-commutative operation and the commutation operation of the motor is optimized by using the line back EMF waveform, respectively. In order to restrain the influence of the backEMF on the torque, the low speed commutation modulation strategy and the high speed commutation modulation strategy are adopted in the process of commutation according to the different rotational speed range. The non-commutative winding current can accurately track the reference current and restrain the commutation torque ripple. The integrated variable structure current controller is designed and the continuous component of the controller is reasonably designed. The switching gain of the switch component is only dependent on the parameter perturbation and the system uncertainty disturbance, which effectively reduces the buffeting caused by the switch component. In order to solve the problem of current distortion caused by backEMF in three-phase four-switch permanent magnet brushless DC motor system, the mapping equation between non-conducting phase reverse EMF and current is established. The regulation mechanism of non-conducting phase current by different adjusting vectors is analyzed. Three effective vector modulation strategies and two effective vector modulation strategies are proposed. The two modulation strategies use different modulation mechanisms of adjusting vector to the non-conducting phase current to suppress the negative effect of the backEMF on the current. The average value of the non-conducting phase current converges to zero, which effectively improves the dynamic and steady-state performance of the current. In this paper, the Lyapunov function is constructed to prove the stability of the two modulation strategies. Based on the stability criterion, a simple method is used to calculate the duty cycle of the adjusting vector. Aiming at the problem that the load capacity and speed range of permanent magnet brushless DC motor system are limited in low-voltage situations, the operating characteristics of three-phase four-switch inverter and boost converter are studied, and the two are combined organically. The topology of boost three-phase five-switch inverter and the three effective vector modulation strategy of boost voltage are proposed. This strategy realizes the booster function of motor system by using the regulation mechanism of the output voltage by the straight-through vector. Effectively expand the load capacity and speed range of permanent magnet brushless DC motor in low voltage field. Through the hardware experiment platform, the proposed current optimization torque ripple suppression strategy, three effective vector modulation. The two effective vector modulation strategies and the topology of the boost three-phase five-switch inverter are experimentally verified. The experimental results show the correctness of the theoretical analysis and the effectiveness of the proposed strategy.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM33

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