磁悬浮无轴承电机悬浮力绕组励磁及控制方式分析

EXCITATION AND CONTROL ANALYSIS OF LEVITATION FORCE WINDING FOR MAGNETIC SUSPENSION BEARINGLESS MOTORS

该文对磁悬浮无轴承电机悬浮力绕组的励磁及控制方式进行了分析。从磁悬浮无轴承电机的运行原理出发,通过将1台该种电机等效成具有不同极数的2台电机,研究电机内磁场和转子的相对运动,得出绕组极数选取方案与等效电机工作状态的关系。进一步推导出绕组极数选取方案与悬浮力绕组励磁方式的关系。从中可以看出绕组极 数选取方案决定悬浮力绕组的电能传递方向及它的励磁方式。针对悬浮力绕组存在的两种励磁及控制方式,重点讨论了悬浮力绕组工作在自励方式时,控制悬浮力绕组励磁电流的方法。提出一种采用逆变器并联电容器的新方法,该方法通过PWM逆变器控制悬浮力绕组中励磁电流。最后,进行了实验研究。

In this paper excitation modes and control stra-tegies of levitation force winding for magnetic suspension bearingless motors are analyzed. From the operation principle of a beaingless motor, the relation between pole-number selec-tion of windings and two equivalent motors operation modes can be obtained by using the equivalence of the motor to two equivalent motors with different pole numbers and studying the relative motion between magnetic field and the rotor. The relation between pole-number selection of windings and excita-tion modes of levitation force winding can be further derived. From the relations, it is concluded that pole-number selection of windings not only determines direction of electrical energy transfer for levitation force winding, but also does its excitation modes. For two kinds of excitation modes and control methods existing in levitation force winding, the paper mainly discusses how to control current in levitation force winding operating under self-excitation mode. A novel method of a capacitor in parallel with inverter is presented, in which current in levitation force winding can be controlled by PWM technique. Finally, experimental results are shown in the paper.