【作者】 吴胜；

【导师】 李朗如； 周理兵；

【作者基本信息】 华中科技大学 ， 电机与电器， 2005， 博士

【摘要】 本文以绕线型感应电机的双馈控制技术(或称双馈电机的控制技术)为研究对象,对双馈电机的数学模型、控制策略、三相高频PWM 整流控制器和矩阵变换器等进行了深入研究。首先利用电机学基本原理,建立M -T坐标系下电机的数学模型,以及在定子磁链定向的矢量控制策略下,电机定、转子电流的关系表达式。通过绕组折算和频率折算,导出双馈电机的等效电路。根据等效电路,导出双馈电机稳态下定、转子侧的功率关系表达式,并分析了双馈电机在各种不同运行状态下的功率流程。为双馈电机的磁场定向矢量控制提供理论基础。明确指出,正是由于频率折算的等效“放大”作用,使得双馈电机能够通过控制转子侧较小的无功功率,达到控制定子侧较大的无功功率,从而实现经济地调节电机功率因数的目的。采用AC/DC/AC 的拓扑结构,构建了双馈电机控制用变换器,变换器整体结构可分为两大模块:AC/DC 整流模块和DC/AC 逆变模块,两部分通过具有直流储能环节的直流母线相联接,使得对两个模块可分别采取不同的控制策略实施控制,且互不干扰,具有整体硬件结构简单,改变DSP 软件编程即可方便的改换成不同的控制策略的优点。其中,整流模块采用三相高频PWM 整流矢量控制技术进行控制,提出了开关频率固定的直接电流滞环控制法,在实现能量双向流动的同时始终保持在接近于1 的高功率因数下工作,充分利用双馈电机能量双向流动的特性,使得能量可回馈利用,提高效率的同时,又由于有效的改善了AC/DC 变换器的电流波形而减少对系统的谐波污染。实验研究证明了该控制策略的可行性,并为实施双馈控制控制提供基础。对DC/AC 模块,采取以定子磁链定向的矢量控制策略,将M -T坐标系的M 轴与定子磁链ψ1重合,使得电机的有功分量与无功分量可分别得以控制。按照定子磁链定向矢量控制策略,采取双闭环控制的结构,以双馈电机的转速以及定子侧的无功功率为控制目标构成控制外环,以双馈电机转子三相电流的滞环跟踪控制为电流控制内环,通过控制转子侧电流达到控制电机定子侧的无功功率和转速的目的。双闭环控制保证了双馈电机的快速响应,实验验证了双馈控制策略的正确性。AC/DC/AC 双馈控制器的硬件结构采取以DSP 为核心的全数字控制系统,简要介绍更多还原

【Abstract】 The double-fed control strategy for wound-rotor induction machine is investigated in this paper. The double-fed machine’s mathematical model and matrix converter as well as three-phase high frequency PWM converter are also studied. Firstly, according to the basic principle of electrical machine, the double-fed machine’s mathematical model under M ? T coordinate system is deduced, stator flux oriented vector control strategy as well as relational expression between stator current and rotor current are also investigated. At the same time, active power and reactive power seen from stator side are also been studied. All the researches provided theoretic base to carry out more research for double-fed control strategy. Secondly, double-fed machine’s equivalence circuit is deduced through winding convert and frequency convert. According to the equivalence circuit and from the point of view of the law of energy conservative, the relational expression of the active power between stator side and rotor side under steady state is analyzed. Moreover, the energy flow direction and distribute process is also studied. Point out definitely that just due to the effect of frequency convert, double-fed control system can regulate power factor at stator side economically by means of control lesser reactive power at rotor side. In this paper, the AC/DC/AC main circuit topological structure is adopted to the control of double-fed machine. So, this kind of converter can be bifurcated as AC/DC converter block and DC/AC inverter block. This converter has two back-to-back 3-arm bridges with DC bus linked electrolytic capacitor, thus the AC/DC module and the DC/AC module can be controlled respectively. The control strategy can be change conveniently as needed by write different DSP program well and the whole hardware maintenance the same. The whole hardware structure can be designed very compactly. The AC/DC converter block is controlled by three-phase high frequency PWM vector control strategy with direct current hysteretic loop control method. Under this control strategy, the converter maintains a high power factor while the energy flows into or out of the converter. The slip energy can be regenerated thus increased the hole system efficiency and reduced harmonic pollution. Experiment results show that the control strategy is feasible The DC/AC module is controlled by stator-flux oriented vector control strategy. When M axis is attached to the stator flux, the active power and reactive power can be controlled respectively. According to stator flux oriented vector control strategy, dual close loop control structure is adopted. The rotor speed and the reactive power of stator side are defined as object function of outer loop. The current of the rotor is defined as object function of inner loop. The rotor speed and reactive power is controlled by the rotor current. In addition, the principle and structure of the stator flux observer is also introduced. This dual close loop strategy ensures the quick-response ability of system. It is concluded that the double-fed control strategy works well. It can be designed very compactly. The AC/DC/AC double-fed controller uses DSP as the key device thus make up the all-digital control system. The other elements are also introduced. The detailed power device hardware structure and control block structure is introduced too. The whole simulation module is made up by simulink blocks in Matlab environment. Dynamic simulations and experiment results show that the whole control strategy is effective and advantaged. Proposed a method of switches acting on current zero-crossing point in matrix converter to control double-fed machine in open loop and carried out experimental study. The bi-direction switch unit formation and main circuit hardware constitution of the matrix convert has introduced. The circuit structures which are using for created control signal and course are also analyzed. Switching element’s current transformation course under every possible work mode and potential problems are analyzed in detail. Further more, corresponding improvement strategy is proposed. According to this strategy, a sample device is made to carry out experiment study. The experiment results show that this control method is correct and feasible. All of these provided useful experience to carry out open-loop control of double-fed machine in future.更多还原