基于三电平拓扑的中压大功率永磁同步电机牵引系统关键技术研究

Employing the high efficiency and energy saving permanent magnet synchronous machines (PMSMs) as traction motors, this project focuses on the key technology of three-level-topology-based medium voltage high power permanent magnet traction system. The current system exhibits the following drawbacks: The harmonic features of different types of PMSMs have significant effects on the harmonic elimination results. In addition, the parameters variations of traction motors have affected the performance of the traction system control considerably. Moreover, the traditional controllers couldn't achieve unity power factor tracking of grid side. Finally, the fundamental wave component generated in the phase current has influenced the system control effect when it operated in the square-pulse state due to the twice beat frequency of grid. Therefore, this research focuses on the following four top technologies：(1) The harmonic characteristics and the parameter variations principles of different types of PMSMs by finite element analysis; (2) The selective principles of single PI flux weakening controller and the SHEPWM+VC control strategy of three-level inverter for different types of PMSMs; (3) The design principles of the resonant controller which can achieve the unity power factor control for grid side of single phase three-level 4-quadrant rectifier; (4) The mechanism of twice beat frequency of grid generated in the DC link and its impact on the control performance of traction motors, as well as the deadbeat control algorithm of the traction motors which can eliminate the impact of the beat frequency. The basic theories and key technologies of three-level-technology-based medium voltage high power permanent magnet traction systems are generalized through theoretical analysis, simulated predictions, prototype machine trial and experimental verifications.

以高效节能永磁同步电机为牵引电机，对基于三电平拓扑结构的中压大功率永磁牵引系统关键技术进行研究。不同结构永磁同步电机的谐波构成影响系统消谐结果，电机参数变化又会影响电机控制性能。此外，传统控制器无法实现网侧单位功率因数跟踪、电网2倍拍频使相电流产生的基波分量影响电机方波运行时的控制效果。针对上述瓶颈，本项目围绕：（1）有限元仿真分析验证不同结构永磁同步电机的谐波特性及其全工况下的参数变化；（2）不同结构永磁同步电机的三电平逆变器SHEPWM+VC控制策略和单PI弱磁控制器选择原则；（3）实现单相三电平四象限整流器网侧单位功率因素控制的谐振控制器设计原理；（4）直流环节2倍拍频产生机理及其对电机控制性能的影响，及消除拍频影响的电机无差拍控制算法等四大关键技术展开研究；通过理论研究，构建仿真模型、原型样机试制和实验验证系统，最终归纳出基于三电平拓扑的中压大功率永磁牵引系统的基础理论和关键技术。

永磁同步电机是由电励磁三相同步电机发展而来，电励磁系统被永磁体所取代，取消了励磁绕组、集电环和电刷，定子与电励磁三相同步电机基本相同，具有比其他交流伺服电机更优越的性能，其与三电平结构相结合产生的三电平拓扑结构的中压大功率永磁牵引系统则具有高压大容量运行，多电平输出，系统绝缘冲击下，谐波特性良好等多电平结构的优点。本课题针对三电平拓扑结构的中压大功率永磁牵引系统不同结构永磁同步电机谐波特性、SHEPWM+VC控制和电PI弱磁控制、单相三电平四象限整流器控制及无差拍控制的关键技术进行研究，其目的在于拓展拓扑应用领域与简化调制策略，本课题的主要研究内容包括：. 研究中压大功率牵引永磁同步电机根据不同类型电机的电压谐波和电流谐波关系，制定相应的三电平逆变器的SHEPWM+VC控制策略设计方法；研究单相三电平四象限整流器网侧单位功率因数跟踪控制的谐振控制器；研究方波控制时单PI弱磁控制器的设计方法和稳定性分析理论；研究加入无差拍控制抑制直流环节出现电网2倍拍频对电机控制器的产生的影响。. 此外，本课题采用有限元法分析不同结构型式永磁同步电机的电磁参数与特性计算方法，得到电机全速运行范围内的参数平面，指导电机控制策略的选择。研究了永磁同步电机在不同模式与同模式不同开关角个数之间实现平滑切换的控制策略，实现了针对不同的调速要求采取不同的调制方式，保证电机系统高效运行。研究对单相三电平整流器使用特定谐波消除调制，控制整流器产生的波形中特定次谐波的分量。研究使用粒子群算法实现SHEPWM开关角的求解，有效降低系统中THD含量。研究基于补偿观测器的三电平逆变器永磁同步电机无差拍控制算法，消除网侧100Hz的拍频对电机运行在方波状态时的影响。. 课题组通过仿真软件MATLAB/SIMULINK对所有理论分析进行了验证，同时搭建了实验样机对仿真的正确性进行了验证。