【作者】 杨钢；

【导师】 邓智泉； 严仰光；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2008， 博士

【摘要】 无轴承开关磁阻电机是利用磁轴承结构与电机定子结构的相似性,将悬浮绕组集成到电机定子中,以同时实现转子的旋转和自悬浮控制。将无轴承技术应用于开关磁阻电机不仅可充分发挥其高速适应性,而且由于对转子径向位置的控制,有望为解决其因不对称磁拉力造成的振动和噪声问题提供一种新的途径。本文以无轴承开关磁阻电机的数学模型、控制策略、功率变换器和电机绕组结构作为研究重点,设计了无轴承开关磁阻电机系统实验平台,实现了电机在多种控制策略下的稳定悬浮。本文在对前人成果深入研究的基础上,改进了无轴承开关磁阻电机的数学模型。新模型不仅考虑了径向悬浮力间的耦合,而且解决了以往模型中电感曲线的顶部凹陷问题。基于无轴承开关磁阻电机的数学模型,本文设计了三种电机控制策略。针对现有文献中超前角计算方法的不足,对主绕组方波电流控制策略进行了改进;根据主绕组磁势和悬浮绕组磁势不同组合对电机转矩和悬浮力的影响,研究了最小磁势控制策略,此控制策略可一定程度地降低电机损耗和转矩脉动;此外针对转速增加时瞬时悬浮力难以控制的问题,设计了平均悬浮力和平均转矩控制策略。给出了绕组功率变换器的设计原则。本文根据无轴承开关磁阻电机的数学模型和运行原理,分析了其对功率变换器的基本要求,提出了变换器的设计原则。依据此原则,在主绕组中采用不对称半桥变换器,在悬浮绕组中采用三相半桥变换器,并分析了变换器的各种工作模态和数学模型。针对悬浮绕组三相半桥变换器实际运行中电流纹波较大和中点电压飘移的问题,提出了改用三相四桥臂变换器的改进措施。本文还优化了无轴承开关磁阻电机的绕组结构。本文将电机本体、功率变换器和控制系统作为一个整体,分析了不同绕组结构对三相半桥变换器中点电压的影响,给出了一组优化结构。此优化结构使变换器两个分裂电容的负载达到均衡。此外根据绕组结构对三相四桥臂变换器公共桥臂的影响,给出了四桥臂变换器下的绕组优化结构。最后本文设计了以DSP和CPLD为核心的无轴承开关磁阻电机控制系统,并在实验样机上进行了实验,实现了无轴承开关磁阻电机的稳定悬浮。更多还原

【Abstract】 Because of similarity between the construction of a magnetic bearing and that of a switched reluctance motor (SRM) stator, a bearingless switched reluctance motor (BSRM) integrates the magnetic suspension winding into the same stator so that the rotor may suspend and rotate at one time. The bearingless technology has been applied to the switched reluctance motor, which could fully enhance its high-speed performance. Moreover, it also provides a new approach to solve the problem of switched reluctance motor’s noises and vibration because it actively controls the radial displacement of a rotor. The dissertation focuses on mathematic models, control strategies of the torque and radial force, power converters and optimal winding arrangements and designs the experimental platform of a bearingless switched reluctance motor. Successful levitation operations are realized based on diverse control strategies.On the basis of research of the former achievements, the mathematic models are revised concerning the couple between radial forces. The new model solves the problems of subsidence at the crown of the inductance’s curve.Based on the principle and mathematic models, three kinds of control strategies are designed. Firstly, aimed at the shortage of the existing method of calculating the current advanced angle, the control strategy of main winding square-wave current is improved. And the influences of different combinations of winding currents on radial force and torque are analyzed. Then a least magnetomotive force strategy is designed. The novel control strategy can decrease torque ripple and motor losses. Aimed at the problem of controlling instantaneous radial force difficultly after the motor speed increases, the control strategy of controlling average radial force and average torque is designed.The designed principle of winding converters is presented. Based on the principle and mathematic models, this dissertation analyzes the requirement of converters and offers the design principle of converters. In order to increase reliability and reduce cost, the asymmetry converter is applied to main winding and the three-phase half-bridge converter is applied to levitated winding. Then all kinds of work states and mathematical models of converters are expounded. Aimed at disadvantages of a levitated winding converter, the improved measure is taken that a three-phase four-leg converter substitutes the three-phase half-bridge converter.Winding arrangement of BSRM is researched. The influence of winding arrangement on the midpoint voltage is analyzed when regarding a motor, power converters and a control system as a whole. As a result, four kinds of optimized winding arrangements are given, which can balance two split capacitors’load of converters. Moreover, according to the influence of winding arrangements on the netrual leg of the three-phase four-leg converter, optimized winding arrangements which are fit for the four-leg converter are offered.According to control strategies, a digital control system for real-time control is designed based on DSP and CPLD and a lot of experiments are completed. The experimental results verify that the rotor shaft may be successfully suspended.更多还原