适用于磁悬浮轴承的新型五相六桥臂开关功放控制策略

具有五自由度全悬浮的磁轴承系统需要5个全桥结构开关功放。为提高开关功率放大器的集成度和母线电压利用率,提出五相六桥臂开关功放拓扑结构。该拓扑结构采用一种新型的混合电流控制方法,对公共桥臂和负载桥臂分别进行控制。其中公共桥臂采用改进型最大电流误差控制,该方法通过增加误差极性判断模块,最大程度提高了五相电流控制的独立性,实现其解耦控制;负载桥臂采用改进型采样保持控制,满足了在不同负载情况下的控制要求。仿真和实验结果均表明,基于新型混合电流控制方法的五相六桥臂开关功率放大器具有电流纹波小,动态响应快,受负载参数影响小,集成度高,硬件接口简单等优点。

A Control Strategy of Novel Five-phase Six-leg Switching Power Amplifiers Applied in Magnetic Levitating Bearing Systems

Magnetic bearing system of five DOF needs five H-bridge switching power amplifiers,in order to enhance integrated level and power density of the power amplifier,a five-phase six-leg topology was adopted in this paper.A hybrid current control method was introduced,in which the control of neutral leg and phase leg was independent.In this control strategy,the control strategy of the neutral leg was the improved maximum current error modulator,it could reduce the couple of five output currents to the largest extent by adding a current error polarity judgment module.The control strategy of other legs was an improved sample-hold modulator,which can satisfy different load conditions varying in a wide range.The simulation and experiment results indicate that the five-phase six-leg switching power amplifier based on the new hybrid current control method has the advantages of low current ripple,fast dynamic response,least association with load parameters,high integrated level,simple logic interfaces and so on.