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三相PWM整流器低开关频率分层模型预测控制

Low Switching Frequency Multi-Layered Model Predictive Control Strategy for Three-Phase PWM Rectifier

  • 摘要:
    目的 随着直流微电网在配电网中使用的不断拓展,大功率三相PWM(Pulse Width Modulation)整流器的重要性日益凸显。与两电平PWM整流器方案相比,采用三相三电平PWM整流器可在获取优异的网侧电能质量的同时大幅提升装置的耐压及有效容量,但其控制目标及复杂度大幅增加。现有的整流器模型预测控制算法在三电平PWM整流器的多目标控制中存在计算量大、权重系数整定困难、开关频率较高的问题。这使得整流器对控制器算力要求高、性能下降,制约了其广泛使用。
    方法 针对上述问题,文章以三相三电平大功率PWM整流器为研究对象,对传统模型预测控制进行改进,提出1种基于电流波形相似系数的低开关频率PWM整流器分层模型预测控制策略,以实现三相三电平PWM整流器的多目标优化控制并搭建了仿真和实验平台进行仿真和实验验证。
    结果 仿真及实验结果显示,该控制策略有效减少了计算量,并可在较低开关频率情况下获得较低的电流畸变率,实现多目标约束下的有效控制。
    结论 可将此控制策略应用于大功率PWM整流器的控制中,减小系统开关损耗,提高其可靠性。

     

    Abstract:
    Objective With the continuous expansion of the use of DC microgrids in distribution networks, high-power three-phase pulse width modulation (PWM) rectifiers are becoming increasingly important. Compared with the two-level PWM rectifiers, three-phase three-level PWM rectifiers can significantly improve the withstand voltage and effective capacity of the devices while obtaining excellent grid side power quality, but their control objectives and complexity are greatly increased. The existing rectifier model predictive control algorithms have problems such as large amounts of calculation, difficulty in setting weight coefficients, and high switching frequency in multi-objective control of three-level PWM rectifiers. As a result, the rectifiers require high computing power from the controllers and have reduced performance, restricting their widespread use.
    Method To solve the above problems, this article took three-phase three-level high-power PWM rectifiers as the research object, improved the traditional model predictive control, and proposed a low switching frequency PWM rectifier multi-Layered model predictive control strategy based on current waveform similarity coefficient to achieve multi-objective optimization control of the three-phase three-level PWM rectifiers. A simulation and experimental platform was built for simulation and experimental verification.
    Result Simulation and experimental results show that this control strategy effectively reduces the amounts of calculation, achieves a lower current distortion rate at a lower switching frequency, and achieves effective control under multi-objective constraints.
    Conclusion This control strategy can be applied to the control of high-power PWM rectifiers to reduce system switching losses and improve system reliability.

     

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