低开关频率下永磁电机控制方法研究

发布时间：2018-08-02 10:38

【摘要】：永磁同步电机控制简单,效率高,在轨道交通中的应用越来越广泛。针对永磁同步电机弱磁扩速的特殊性,本文分析了负直轴电流补偿弱磁控制方法,利用电机电压合成矢量与直流侧能够提供的最大电压矢量幅值之差,通过PI控制器闭环校正直轴电流指令来实现弱磁。同时大功率牵引传动系统中要求开关频率较低,加剧了永磁同步电机矢量控制的电流耦合问题,而较长的开关周期也使数字控制固有的延时问题更加突出,影响了电机的控制性能。本文从复矢量域建立永磁同步电机数学模型,推导出系统传递函数,从理论上分析了电流耦合问题。对双PI调节器解耦方法进行了深入分析,研究了其改进形式,并通过传递函数画出系统闭环零极点分布图和伯德图对几种解耦控制优化方法进行了对比讨论。相比较前馈解耦和反馈解耦,改进型双PI解耦控制对电机参数具有更好的鲁棒性,解耦效果更好。本文分析了数字控制原理及延时产生基理,研究了角度补偿和q轴电流误差补偿两种延时补偿方法。两者均可改善低开关频率下的控制性能,后者动态性能更好。在加入延时补偿条件下,对低开关频率下几种解耦控制方法的解耦效果做了分析对比。研究分析了在低开关频率下适合永磁同步电机的解耦控制与延时补偿相结合的控制优化方法。本文在MATLAB/Simulink中搭建了永磁同步电机传动系统仿真模型,并搭建了基于DSP28335的7.5kW永磁同步电机牵引传动系统实验平台。分别在仿真和实验中对弱磁控制、解耦控制方法和延时补偿方法进行了分析,验证了控制优化方法的准确性和可行性。
[Abstract]:Permanent magnet synchronous motor (PMSM) is widely used in rail transit because of its simple control and high efficiency. Aiming at the particularity of weak magnetic expansion of permanent magnet synchronous motor (PMSM), this paper analyzes the negative direct axis current compensation weak magnetic field control method. The difference between the motor voltage synthesis vector and the maximum voltage vector amplitude which can be provided by DC side is used. The weak magnetic field is realized by Pi controller closed loop correction of straight axis current instruction. At the same time, the low switching frequency is required in the high-power traction drive system, which exacerbates the current coupling problem of the vector control of the permanent magnet synchronous motor, and the long switching period also makes the inherent delay problem of digital control more prominent. The control performance of the motor is affected. In this paper, the mathematical model of permanent magnet synchronous motor (PMSM) is established in complex vector domain, the system transfer function is derived, and the current coupling problem is analyzed theoretically. In this paper, the decoupling method of double Pi regulator is deeply analyzed, and its improved form is studied. Several decoupling control optimization methods are compared and discussed by drawing the closed loop zero and pole distribution diagram of the system with transfer function and Byrd diagram. Compared with feedforward decoupling and feedback decoupling, the improved dual Pi decoupling control has better robustness and better decoupling effect on motor parameters. In this paper, the principle of digital control and the principle of delay generation are analyzed, and two delay compensation methods, angle compensation and Q axis current error compensation, are studied. Both can improve the control performance at low switching frequency, and the latter has better dynamic performance. Under the condition of adding delay compensation, the decoupling effect of several decoupling control methods at low switching frequency is analyzed and compared. The optimization method of decoupling control and delay compensation for PMSM with low switching frequency is studied and analyzed. In this paper, the simulation model of permanent magnet synchronous motor drive system is built in MATLAB/Simulink, and the experimental platform of 7.5kW permanent magnet synchronous motor traction drive system based on DSP28335 is built. In the simulation and experiment, the weak magnetic control, decoupling control and delay compensation are analyzed, and the accuracy and feasibility of the control optimization method are verified.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM341

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