【作者】 高瑾；

【导师】 胡育文；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2007， 博士

【摘要】 本文核心内容是无刷直流电动机直接转矩控制技术的研究,包括理论与实践两个方面。迄今为止,直接转矩控制技术已成功地应用于异步电动机和正弦波永磁同步电动机,但无刷直流电动机现在仍然是直接转矩控制技术尚未深入涉及的领域,所以该项研究具有理论意义。直接转矩控制技术具有优良的动态性能,实现简单,也便于实现无速度传感器运行。对于结构简单的无刷直流电动机而言,应用该技术有望达到两个目的:首先是提高无刷直流电动机调速系统的动、静态性能,其次是不增加系统的复杂性,保持无刷直流电动机调速系统原有的简洁,所以本文研究具有现实意义。本文提出了无刷直流电动机直接转矩控制方案,通过转矩滞环比较器与磁链滞环比较器选择最优电压空间矢量作用于电机,定子磁链跟踪圆锯齿轨迹。解决了以下三个具有普遍性的问题:两相导通模式下的电压空间矢量计算;两相导通模式下的磁链计算;非正弦量的坐标变换,为后续的进一步深入研究奠定了基础。直接转矩控制方案中系统比较复杂,为解决这一不足,本文提出了无刷直流电动机直接自控制方案,将直接自控制技术首次应用于无刷直流电动机。该方案采用三相导通方式,不存在关断相,定子磁链跟踪六边形轨迹,系统组成简单,实现容易。直接转矩控制方案实现起来比较复杂,直接自控制方案的电流脉动较大。为解决上述两种方案的不足,达到增强实用性的目的,本文在前述研究的基础上提出了一种全新的理论:无刷直流电动机超空间矢量理论。该理论采用两相导通方式,使用三维正交空间坐标系,将关断相的电压放置到与xy平面垂直的z轴,电压空间矢量与磁链空间矢量均在三维空间中运动变化,并将其定义为超空间矢量,利用电压超空间矢量在xy平面上的投影来控制定子磁链超空间矢量在xy平面上的投影。根据该理论构建的系统在本文所提出的三种方案中实现最简单。因为电机仅是调速系统的一个组成部分,把系统割裂开来的研究方法是不完整的。本文根据一体化的思想,将研究范围延伸到电机本体上,以期望取得整体最优控制效果。首先分析了无刷直流电动机参数与电流脉动的关系,包括稳态时的电流脉动与起动过程中的电流冲击,指出影响电流脉动的主要电机参数是自感。针对无刷直流电动机自感偏小的特点,分析了增大自感的方法及其优缺点。将一体化的思想从无刷直流电动机延伸到正弦波永磁同步电动机,分析了三个关键参数:直轴电抗、交轴电抗、永磁体磁链对调速性能的影响,提出一种图形优选法来优选这三个参数,使得整个调速系统的利用率最大。更多还原

【Abstract】 The core content was direct torque control of brushless direct current motor, including theory and experiment. Up to now, direct torque control had used successfully in asynchronous motor and permanent magnet synchronous motor, but not in brushless direct current motor. Therefore, the research of this paper had theory creation. Direct torque control had excellent dynamic performance, easy realization, convenient for realization of non-velocity sensor. For the simple structure brushless direct current motor,application of direct torque control would acquire two result: firstly, the dynamic and stable performance of brushless direct current motor get improvement, secondly, the complex of brushless direct current motor control system did not increase. So the research of this paper get practical meaning.The direct torque control strategy of brushless direct current motor was proposed. The optimal voltage space vector was chosen to control the motor by torque comparator and flux comparator. The locus of stator flux was sawtoothed circle. The direct torque control strategy created whole fundamental theory, and solved three problem: voltage vector’s calculation under two-phase conduction mode; the flux calculation under two-phase conduction mode; the coordinate transformation of non-sinusoidal variable. That was the foundation of next research.To solve the complex of direct torque control strategy, the direct self control strategy of brushless direct current motor was proposed. The strategy used three phase conduction mode to eliminate turn-off phase, as a result, the control system get simplified. The stator flux followed hexagon locus. The system’s combination was simple and easily realization.The direct torque control strategy was complicated, and the direct self control strategy had the deficiency of current pulsation. To solve these two problems, a newly theory: hyper space vector theory of brushless direct current motor was proposed. The theory used two phase conduction mode, and three dimension space coordinate was applied. The voltage of turn-off phase was put on the z axis, which perpendicular to xy plane. The voltage space vector and flux space vector moved in three dimension space. The project of voltage space vector were used to control the project of flux space vector. The control system of hyper space vector theory was simplest within the three mentioned strategy. It had bright development in practice.The motor was only a fraction of speed control system, it was not a scientific method to research only one part of a whole system. Besides the control strategy, the aim of this paper was to research the motor, so as the whole system performance get optimized. The relation between the brushless direct current motor parameters and current pulsation was analyzed firstly, including stable current pulsation and start-up current shock. The critical parameter was induction. As the induction of brushless direct current motor was always small, the paper analyzed the method how to increase the induction, with their merits and disadvantage.The permanent magnet synchronous motor was analysed according to the whole system theory, and three critical parameters were selected: direct axis reactance, quadrature axis reactance, permanent magnet flux. The effects of these three parameter on speed control performance was analyzed, furthermore, a graphic method was proposed to optimize these three parameter, as a result, the control system maintained maximum utilization.更多还原