EHPS用四相无刷直流电机的弱磁策略与实验研究

Research and Experiments on Field-weakening Control Method of a Four-phase Brushless DC Motor for EHPS Applications

电动液压助力转向系统EHPS(Electro-Hydraulic Power Steering)在快打方向盘时存在跟随特性较差的问题,即驱动电机瞬时转速不足。本文通过分析一种新颖结构的EHPS用四相无刷直流电机,设计了四相半桥驱动电路,并基于超前导通的算法思想设计了一种低成本弱磁升速方法。同时根据EHPS的转速要求,设计了基速以下和基速以上两种工作模式及其切换机制。最后通过实验验证了四相无刷直流电机可以达到EHPS的转速要求,为下一步EHPS台架调试奠定了基础。

The electro-hydraulic power steering system （EHPS） has the problem of the poor follow-up characteristic when steering fast, i.e. the drive motor＇s instantaneous speed is insufficient. In this paper, a novel EHPS＂ four-phase brushless DC motor structure was analyzed and a four-phase half-bridge circuit was designed. A low-cost field-weakening method is designed based on the conduction in advance control algorithm. At the same time, two modes of operation both below base speed and above base speed and their switching mechanism were designed according to the requirements of the EHPS driven speeds. Finally, the experiment of the four-phase brushless DC motor can reach EHPS speed requirements, which laid the foundation for the next step EHPS bench debugging.