【作者】 王波；

【导师】 贺益康；

【作者基本信息】 浙江大学 ， 电机与电器， 2010， 硕士

【摘要】 永磁同步电机(PMSM)功率密度大、功率因数高,直接转矩控制(DTC)原理简单、转矩响应快,结合二者优点的PMSM DTC系统在电动汽车、军事、家用电器等诸多领域获得了越来越广泛的应用,DTC调速系统的可靠性也随之越来越受重视。PMSM DTC系统采用逆变器供电,由于电力电子器件的脆弱性,逆变器故障在各类故障中最为频繁。由于DTC将电机与逆变器作为一个整体进行控制,若逆变器发生故障将导致整个变频调速系统失去运行能力,因此很有必要对逆变器故障时系统的容错运行进行深入研究。三相四开关容错型逆变器供电方案和其他方案相比,既节约系统成本又有较好性能,故本文选取三相四开关供电方案作为容错运行方案。容错运行状态下供电条件的恶化和DTC固有的转矩脉动大的特点相叠加,使得性能恶化,因此亟待解决这种新型供电条件下的动静态特性矛盾,即在抑制转矩脉动的同时又能保持DTC的快速动态响应特性,这是本论文研究的主体内容。本文的主要工作包括:1.三相四开关逆变器供电PMSM传统DTC研究。在三相六开关逆变器供电的PMSM传统DTC运行研究的基础上,通过分析三相四开关逆变器容错拓扑结构,重定义了三相四开关逆变器电压空间矢量和相应的传统DTC的开关表。实现了三相四开关逆变器供电的PMSM传统DTC运行。2.三相四开关逆变器供电PMSM SVPWM-DTC研究。受三相六开关逆变器供电条件下空间矢量调制(SVPWM)技术能显著削弱转矩脉动的启发,在三相四开关逆变器供电条件下引入SVPWM,形成SVPWM-DTC方案来优化系统性能。3.三相四开关逆变器供电PMSM SMC-DTC研究。鉴于滑模变结构控制(SMC)抗干扰性好、鲁棒性强、适合非线性控制的突出优点,引入滑模控制形成SMC-DTC方案,并将其控制效果和SVPWM作比较。4.直流母线电容电压不平衡程度的抑制和不平衡条件下的计算。三相四开关逆变器容错重构方案中逆变器故障相对应的电机绕组是通过直流母线上串联的两个电容的中点来供电的,运行中伴随着电容的充放电该中点的电位会发生偏移,最终会导致运行失败。本文在直流母线电容电压不平衡条件下进行了仿真分析和实验研究,提出了一种软硬件相结合以控制直流母线电容电压不平衡度的行之有效的方案,并针对普通SVPWM算法不适用于三相四开关逆变器供电条件的问题提出了一个新SVPWM算法并将其应用于SVPWM-DTC和SMC-DTC中,改善了三相四开关逆变器供电的PMSM DTC系统的运行性能。更多还原

【Abstract】 Permanent Magnet Synchronous Motor (PMSM) features high power density and high power factor, direct torque control (DTC) is famous for its simplicity and fast torque response, therefore, PMSM DTC systems, with the advantages of both, are widely applied in electric vehicles, military, home appliances and many other fields, and their reliabilities have been paid more and more attention. PMSM DTC system usually use voltage source inverter, due to the frangibility of the power electronic devices, various faults could occur in the inverter. Because DTC considers motor and inverter as a whole for control, inverter faults could result in lossing the operation ability for drive system. So it’s necessary to conduct a in-depth study of fault-tolerant operation for inverter faults. Compared to other inverter fault-tolerant schemes, three-phase four-switch inverter costs less and has better performance, so in this thesis three-phase four-switch inverter is selected for fault-tolerant operation. Deterioration of power supply added to the inherent large torque ripple of DTC makes the ripple of torque even more prominent. So it is urgent to solve the contradiction of dynamic and static characteristics under the new condition of power supply, namely suppressing of torque ripple while basically maintaining the fast dynamic response. This thesis’s main work include:1. Three-phase four-switch inverter fed PMSM conventional DTC. based on the operation of three-phase six-switch inverter fed PMSM conventional DTC, the voltage space vector and the corresponding switch table is redefined for three-phase four-switch inverter by analyzing its topology. Finally three-phase four-switch inverter fed PMSM conventional DTC is realized.2. Three-phase four-switch inverter fed PMSM SVPWM-DTC. By the inspiration of the fact that the technique of Space Vector Pulse Width Modulation (SVPWM) is able to reduce the torque ripple significantly in the three-phase six-switch inverter system, SVWPM is introduced in the three-phase four-switch inverter to optimize the performance of drive system.3. Three-phase four-switch inverter fed PMSM SMC-DTC. Sliding mode control features outstanding merits of good interference rejection, good robustness, and it’s applicable for nonlinear control, and it is introduced for the three-phase four-switch inverter to realize the SMC-DTC strategy. The control results are compared with theSVPWM-DTC.4. Suppression of DC bus capacitor voltage imbalance and the calculation under theunbalance condition. The motor winding corresponding to the fault phase of theinverter is connected to the midpoint of the two dc-link capacitors in series, and alongwith capacitor charging and discharging, the voltage will change. Simulation analysisand experimental study are performed under the unbalance condition in this thesis.更多还原