基于线反电势估算的无刷直流电机无传感器控制方法研究

发布时间：2019-06-10 19:35

【摘要】：相较于传统的有刷电机,永磁无刷直流电机具有寿命长、调速范围宽、功率密度大、效率高等优势,在电动工具领域得到了广泛应用。位置传感器为无刷直流电机的换相控制提供实时的转子位置信息,但其增加了系统的成本,对安装精度要求较高且对温度敏感,并不适用于对可靠性要求较高的应用场合。因此本文对无刷直流电机无传感器驱动控制技术进行了深入研究。首先,对基于线反电势估算的无传感器换相控制方案进行研究。建立了自然坐标系下无刷直流电机的数学模型,对无刷直流电机的三相六状态控制原理和调速原理进行了分析和总结。研究了基于线反电势过零检测的换相控制原理,合理地简化了线反电势的计算公式,给出了电机正转和反转时的换相控制方案,并进行仿真验证。其次,对基于短时脉冲检测的无传感器起动方法进行研究。分析了通入短时检测脉冲后,定子绕组等效电感与转子初始位置区间的关系,研究了转子初始位置定位和位置闭环加速起动的原理,给出了相应的控制方法。考虑了转子位于临界区间的检测精度有限的问题,对检测电流设置了优先级。在MATLAB/SIMULINK中搭建三相无刷直流电机控制系统模型,仿真对比了该起动方法与传统三段式起动法的起动性能。然后,对基于线反电势估算的无传感器控制方案存在的换相位置检测误差进行了分析。讨论了低通滤波器移相导致的换相误差,针对电机不同转速,提出了“60°-α”和“120°-α”的补偿策略,并对其进行仿真验证。分析了逆变器开关管PWM控制所产生的线反电势估算误差,并推导了该误差的表达式。仿真对比不同脉宽调制方式控制下,换相位置检测误差随转速的变化情况。最后,对本文提出的换相控制策略和补偿策略进行实验验证。研究了控制系统的硬件结构;设计了基于短时脉冲检测的起动控制和基于线反电势估算的换相控制的软件流程,并编写程序。搭建实验平台,分析实验结果,验证了所述方法的正确性和可行性。
[Abstract]:Compared with the traditional brushed motor, permanent magnet brushless DC motor has many advantages, such as long life, wide speed range, high power density and high efficiency, so it has been widely used in the field of power tools. The position sensor provides real-time rotor position information for the commutation control of brushless DC motor, but it increases the cost of the system, requires high installation accuracy and is sensitive to temperature, and is not suitable for applications with high reliability requirements. Therefore, the sensorless drive control technology of brushless DC motor is deeply studied in this paper. Firstly, the sensorless commutation control scheme based on line back EMF estimation is studied. The mathematical model of brushless DC motor in natural coordinate system is established, and the three-phase six-state control principle and speed regulation principle of brushless DC motor are analyzed and summarized. The principle of commutation control based on zero crossing detection of line back EMF is studied, the calculation formula of line back EMF is simplified reasonably, and the commutation control scheme of motor forward and reverse is given, and the simulation verification is carried out. Secondly, the sensorless starting method based on short-time pulse detection is studied. The relationship between the equivalent inductance of stator winding and the initial position interval of rotor is analyzed after the short time detection pulse is introduced. The principle of rotor initial position positioning and position closed loop acceleration starting is studied, and the corresponding control method is given. Considering the limited detection accuracy of the rotor in the critical range, the priority of the detection current is set. The control system model of three-phase brushless DC motor is built in MATLAB/SIMULINK, and the starting performance of the starting method is compared with that of the traditional three-stage starting method. Then, the commutation position detection error of sensorless control scheme based on line back EMF estimation is analyzed. The commutation error caused by phase shift of low pass filter is discussed. The compensation strategies of "60 掳- 伪" and "120 掳- 伪" are put forward according to the different rotating speed of the motor, and the simulation results are carried out. The estimation error of line back EMF caused by PWM control of inverter switch is analyzed, and the expression of the error is derived. The variation of phase change position detection error with rotating speed under different pulse width modulation (PWM) control is simulated and compared. Finally, the commutation control strategy and compensation strategy proposed in this paper are verified by experiments. The hardware structure of the control system is studied, the software flow chart of starting control based on short time pulse detection and commutation control based on line back EMF estimation is designed, and the program is programmed. The experimental platform is built, the experimental results are analyzed, and the correctness and feasibility of the method are verified.
【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】：TM33

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