基于端电压平均值和准滑模观测器的无刷直流电机控制

倪有源 余长城 陈浩

Abstract：Sensorless control is the trend of development in the future. In order to improve the accuracy of a sensorless brushless DC （BLDC） motor control system， based on an average terminal voltage， a quasi sliding mode observer with a line back electromotive force （EMF） was proposed. To reduce chattering in the traditional sliding mode observer， a saturation function with boundary layer was employed and the average terminal voltage was sampled. In the control strategy， line back EMF without filter circuit and phase compensation module were obtained， and by using of the line back EMF as commutation signal the problem of phase back EMF as commutation signal lagging 30° electrical degree was eliminated with the actual commutation signal. The virtual hall signals corresponding the line back EMF determine the commutation signals. Compared with the traditional sliding mode control method， the proposed method can be used to obtain low torque ripple and fast response speed. The simulation and experiment results show that the proposed method is effective and correct .

Keywords：sensorless control; brushless DC motor; average terminal voltage; line back electromotive force; quasi sliding mode observer

0 引 言

永磁無刷直流电机具有控制简单、可靠性高以及效率高等优点，广泛应用于各种场合[1]。传统的无刷直流电机采用霍尔传感器检测转子位置从而换相，然而位置传感器却限制了无刷直流电机在一些场合的应用而且造成电机成本过高。因此，无位置传感器无刷直流电机已成为关注的热点之一。

国内外学者对于无位置传感器控制技术进行了广泛研究。常用的转子位置检测方法有反电势检测、续流二极管导通检测、磁链检测、观测器检测[2-7]等。在观测器检测方法中，滑模观测器具有良好的鲁棒性、简化的外围参数[8]等优点而被众多学者深入研究。滑模观测器的设计常常在估值振荡、相位延迟、收敛速度、系统能量损耗等因素之间进行取舍。文献[9-10]针对无位置传感器电动汽车驱动系统分别将高阶非奇异终端模型和模糊逻辑引入滑模观测器，根据滑模运动的情形来消除估算振荡，确保系统的稳定性和鲁棒性，整个系统的运算量十分巨大。文献[11]采用了一种双曲正切函数代替传统滑模函数来削弱估值振荡，同时将线反电势加入状态方程增加转子估算的准确性，这种结合使用的方法无疑增加了运算的复杂性，使得在宽转速电机推广应用中受到限制，动态响应也很差。文献[12]采用分段饱和函数代替简单的符号函数，滑模输入误差在边界层内外适用于分段函数中不同的条件，从而有效地减小了估值振荡的问题，但是并没有将分段函数进行理论推导，没有和实验匹配的理论支撑。……