开式绕组无刷电动机换相转矩脉动抑制研究

Research on Commutation Torque Ripple Suppression of Open Winding Brushless DC Motor

开式绕组无刷直流电动机无中性点,各相绕组电气隔离,可实现各相绕组的独立控制。介绍了开式绕组无刷直流电动机的数学模型,分析了互感作用下各相电流变化之间的影响,以及同一母线供电时续流对非换相相电流的影响;对开式绕组无刷直流电动机的换相过程电流进行分析,得出在理想反电势下关断相和导通相电流变化速率相等可保证非换相相电流不变,从而保持电磁转矩不变。提出了采用重叠换相相电流闭环控制方法来抑制换相转矩脉动,推导出重叠换相法关断相施加电压和延迟关断时间公式,利用滑模观测器观测反电势并计算得到电磁转矩。Matlab仿真和试验结果验证了重叠换相相电流闭环控制可以有效抑制开式绕组无刷直流电动机换相转矩脉动。

The open winding brushless DC motor has no neutral point,and the phase windings are electrically isolated,which can realize independent control of each phase.Firstly,the mathematical model of open winding brushless DC motor is introduced,the influence of each phase caused by the mutual inductance and the impact of the diode freewheeling for non-commutation phase with the same bus power supply are analyzed.Secondly,the current commutation process of open winding brushless DC motor during the commutation period is analyzed.It is concluded that if the turn-off and the conduction phase current with the same change rate,under the ideal Back EMF condition,the non-commutation phase current is constant,then the electromagnetic torque remains the same.Thirdly,the working principle and process of overlapping commutation with phase current closed-loop control are given,the voltage applied on turn-off phase and delay shutdown time formulas in overlapping commutation are derived,electromagnetic torque is calculated by the Back EMF which is observed by sliding mode observer.Finally,the method of overlapping commutation with phase current closed-loop control are carried on the Matlab simulation analysis,the experimental results indicate that the control method can realize the commutation torque ripple suppression of open winding brushless DC motor.