永磁同步电机系统死区效应抑制策略研究

发布时间：2019-06-09 23:47

【摘要】：永磁同步电机由于其结构紧凑,转矩-电流比大等特点得到了广泛的应用。然而逆变器引入的死区会使系统产生电流畸变与转矩波动,限制其在高精度场合的应用。对电机转矩波动的研究已有大量相关文献,然而对逆变器死区所致的电机电流谐波抑制的研究则相对较少。电流谐波会导致电机发热,效率下降,并影响电机的控制效果,因而,对逆变器死区引起的电流谐波进行抑制是十分重要的。在永磁同步电机模型的基础上,针对目前缺乏对永磁同步电机系统死区的详细分析,建立永磁同步电机的谐波数学模型,并探究了永磁同步电机系统中死区时长、PWM调制与采样方式对逆变器死区所致电流畸变的影响,以及不同的电感、电势、电机转速等系统变量与逆变器死区共同作用时对电流谐波的影响。为选取合适的方法对逆变器死区所致电流谐波进行抑制,将现有的优化控制算法归纳为两类,分别是基于特定次数谐波抑制的控制方法与基于全频域谐波抑制的控制方法,并各选择了一种具有代表性的控制方法来对控制器进行设计,通过比较二者对死区效应的抑制效果来对这两类控制方法进行比较。对于全频域谐波抑制方法,将死区时间看作扰动,采用自抗扰控制。首先通过对传递函数的频域分析,来归纳参数选择依据。接下来定量证明自抗扰控制器具有着抑制死区效应的能力,并设计相应的二阶自抗扰控制器,通过仿真验证了其具有抑制死区效应的能力。并优化控制器参数,分别实现了扰动的无差观测、对转速跟随性能的优化以及对相电流正弦性的优化,并得出一阶自抗扰控制器可以更好地抑制死区效应的结论。最终探究了噪声下控制器的鲁棒性。对于特定次数谐波抑制方法,采用基于旋转坐标系的谐波注入法。在设计过程中,设计了平均值滤波器以解决现有数字滤波器的带宽与相应速度存在矛盾的问题;引入前馈控制与交叉耦合项以解决多电流环响应慢的问题。经仿真证明所设计的控制器能够实现死区效应的抑制,谐波电流中的5,7次谐波下降效果明显。最终对自抗扰控制与谐波注入法进行了比较,通过二者的比较,归纳出了一些关于特定次数谐波补偿法与全频域谐波补偿法的特点及所适用的场合。在理论设计与仿真分析的基础上,利用所设计的基于DSP的硬件实验平台,对所设计的两种控制器进行了对比试验。实验结果证明了两种方法可以对永磁同步电机系统死区效应进行有效抑制,从而验证了算法的可行性。
[Abstract]:Permanent magnet synchronous motor (PMSM) has been widely used because of its compact structure and large torque-current ratio. However, the dead time introduced by inverter will cause current distortion and torque fluctuation, which limits its application in high precision occasions. There are a lot of related literatures on motor torque fluctuation, but the research on motor current harmonic suppression caused by dead time of inverter is relatively few. Current harmonics will lead to the heating of the motor, the decrease of efficiency, and affect the control effect of the motor. Therefore, it is very important to suppress the current harmonics caused by the dead time of the inverter. Based on the permanent magnet synchronous motor model, aiming at the lack of detailed analysis of the dead time of the permanent magnet synchronous motor system, the harmonic mathematical model of the permanent magnet synchronous motor system is established, and the dead time length of the permanent magnet synchronous motor system is discussed. The influence of PWM modulation and sampling mode on the current distortion caused by dead time of inverter and the influence of different inductance, electric potential, motor speed and other system variables on current harmonics when different system variables such as inductance, electric potential and motor speed interact with the dead time of inverter. In order to select a suitable method to suppress the current harmonics caused by the dead time of the inverter, the existing optimal control algorithms are classified into two categories, which are the control methods based on specific harmonic suppression and the control methods based on full frequency domain harmonic suppression. A representative control method is selected to design the controller, and the two control methods are compared by comparing the suppression effect of the two methods on the dead time effect. For the full frequency domain harmonic suppression method, the dead time is regarded as disturbance, and the automatic disturbance rejection control is adopted. Firstly, through the frequency domain analysis of the transfer function, the basis of parameter selection is summarized. Then it is quantitatively proved that the ADRC has the ability to suppress the dead-time effect, and the corresponding second-order ADRC is designed. The simulation results show that the ADRC has the ability to suppress the dead-time effect. The parameters of the controller are optimized, and the zero-error observation of disturbance, the optimization of speed following performance and the optimization of phase current sinusoidal are realized respectively, and the conclusion that the first-order ADRC can better suppress the dead-time effect is obtained. Finally, the robustness of the controller under noise is discussed. For the harmonic suppression method of specific times, the harmonic injection method based on rotating coordinate system is adopted. In the design process, the average filter is designed to solve the contradiction between the bandwidth of the existing digital filter and the corresponding speed, and the feedforward control and cross-coupling term are introduced to solve the problem of slow response of multi-current loop. The simulation results show that the designed controller can suppress the dead-time effect, and the seventh harmonic drop effect is obvious in the harmonic current. Finally, the ADRC and the harmonic injection method are compared. through the comparison of the two methods, the characteristics and applicable occasions of the specific harmonic compensation method and the full frequency domain harmonic compensation method are summarized. On the basis of theoretical design and simulation analysis, the two kinds of controllers are compared and tested by using the designed hardware experiment platform based on DSP. The experimental results show that the two methods can effectively suppress the dead-time effect of permanent magnet synchronous motor (PMSM) system, which verifies the feasibility of the algorithm.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM341

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