三电平理论

华中科技大学

硕士学位论文

三电平逆变器SVPWM控制策略的研究

姓名：刘亚军

申请学位级别：硕士

专业：控制理论与控制工程

指导教师：程善美

20080604

摘要

三电平逆变器输出由于具有更高的电能质量、更低的谐波含量，更好的电磁兼容性以及更低的开关损耗等优点，在中高压大容量交流调速领域得到了广泛的应用。但是，三电平逆变器也存在不少关键问题，如三电平算法的简化问题，过调制区中点电压控制问题，以及在高压运行时系统的稳定性问题。鉴于以上存在的问题，本论文深入地研究了三电平逆变器的结构，原理，控制策略，电容中点电压的控制，死区补偿，过调制处理以及SVPWM算法的实现。

论文在论叙二极管箝位三电平逆变器的结构和工作原理的基础上，分析了三电平逆变器的SVPWM调制策略，提出了一种实用的易于数字化实现的三电平SVPWM 算法。在该算法的基础上通过修改小矢量的作用时间给出了基于滞环控制和PI控制的电容中点电压控制策略，并得到了很好的效果。同时，论文对三电平逆变器的死区补偿和过调制处理进行了深入的研究，并且提出了一些新的方法来解决在过调制情况下的中点电压平衡问题，研究了三电平逆变器的死区实现方案和补偿策略，仿真实验证实了所提出的策略达到了预定的效果。为了验证所提出的三电平SVPWM 算法，本文在MATLAB下建立了基于三电平逆变器的感应电动机V/F控制系统和矢量控制系统，仿真结果验证了所提出的三电平空间矢量PWM算法是可行有效的。

论文对三电平逆变器的SVPWM算法的实现进行了研究，基于DSP和CPLD提出了两种实现方法。一种是采用数字信号处理器TMS320LF2407A中的两个事件管理器巧妙实现了三电平SVPWM算法；另一种是利用TMS320LF2407A和EPM240T100C5组成组合逻辑来实现。实验结果进一步证实了所做的研究工作和所提出的算法是实际可行的。

关键词：三电平逆变器SVPWM算法中点电压控制死区补偿过调制

Abstract

Because of the superiority such as higher power quality, lower harmonic components, better electromagnetic compatibility, and lower switching losses in its output, three-level inverter is applied widely in high-voltage and high-power applications. However, there are many key problems in the three-level inverter, such as simplifying the algorithm of three-level, the neutral point fluctuation in overmodulation region, and the stability issues of the system in the high-voltage performance. In light of the above existing problems, the thesis thoroughly investigates the structure, principle, control strategies, neutral point balancing, dead-time compensation, overmodulation and the realization of SVPWM algorithm in the diode-clamped three-level inverter.

On the basis of describing the structure and principle of diode-clamped three-level inverter, the thesis analyzes the SVPWM modulation strategies of three-level inverter, and proposes the SVPWM algorithm which is practical and easily digital realization. It proposes a neutral point control strategy based on hysteresis control and PI control through modifying the working time of small vector on the basis of the algorithm, and achieves a good result. At the same time, the thesis completely investigates the dead-compensation and overmodulation in three-level inverter, and proposes a new scheme to solve the neutral point unbalancing for operating a three-level inverter in overmodulation region. It also investigates the schemes of dead-time setting and the dead-compensation. The simulation results confirm that the proposed strategy achieve the intended results. In order to verify the proposed three-level SVPWM algorithm, this thesis based on MATLAB software establishes induction motor V/F control system and vector control system which is based on three-level inverter, and the simulation results show the proposed three-level space vector PWM algorithm is feasible and effective.

In this thesis, the realization of the SVPWM algorithm for three-level inverter has been studied, and two methods based on the DSP and CPLD are proposed. One method achieves skillfully the three-level SVPWM algorithm by making use of two events manager of the digital signal processor TMS320LF2407A, another is the use of