基于三相半桥功率变换器的无轴承开关磁阻电机绕组结构分析

无轴承开关磁阻电机兼有开关磁阻电机和磁轴承的优点。功率变换器是无轴承开关磁阻电机的重要组成部分，其控制绕组电流，对电机旋转和悬浮性能有重要影响。悬浮绕组功率变换器采用三相半桥结构时，由于负载的不对称，存在中点电压漂移问题。该文简要介绍了电机悬浮原理和数学模型，将功率变换器和电机作为一个整体，分析了中点电压漂移的原因及绕组配置对中点电压的影响。给出了5种绕组结构形式下，各相悬浮力之和及其对中点电压的影响。通过合理配置绕组结构，使电机在恒定径向负载的情况下，中点电压波动大为减小。给出了4种优化的无轴承开关磁阻电机绕组结构。实验结果证明了理论分析的正确性。

Analysis of Winding Arrangements of Bearingless Switched Reluctance Motors Based on Three-phase Half-bridge Power Converter of the Levitation Windings

Bearingless switched reluctance motors have integrated merits of general switched reluctance motors and magnetic bearings. The power converter which is one of important components of bearingless switched reluctance motors controls current of motor windings. Therefore it mostly influences the rotation and levitation of bearingless motors. When the topology of levitated-windings power converters is three-phase half-bridge, the midpoint voltage of converters unbalances with asymmetric load. In this paper after the principle of radial force generation and mathematical model of motor are briefly introduced, the reason for imbalance of midpoint voltage and the influence of windings arrangement on midpoint voltage are analyzed when regarding the power converter and motor as a whole. The sum of every phase levitated force and the influence of the sum on midpoint voltage are obtained with five kinds of windings arrangement. On condition that the reasonable structure of windings is arranged, the imbalance of midpoint voltage is alleviated heavily with the invariable radial load. At last four kinds of optimized windings arrangement are given. The experimental results verify the correctness of theoretic analysis.