基于模糊控制三电平Boost直流变换器输出电容均压方法

Output Capacitor Voltage Balance Control Method of Three-Level Boost DC-DC Converter Using Fuzzy Controller

摘要: 本文针对应用于三相非隔离光伏并网发电逆变器中三电平Boost直流变换器启动建压过程时，可能出现的中点(Neural-Point, NP)电位不平衡问题和后级逆变电路调制策略对中点电位的影响，在三电平Boost直流变换器功率级提出了一种实现中点电位平衡的模糊控制策略。采用模糊控制器可自适应地改变三电平Boost直流变换器开关管的占空比大小，不仅在启动过程中(直流母线建压时)，而且在并网逆变器稳定工作时，都能实现直流侧输出电容的均压,并获得良好的动态和静态性能。论文中为三电平Boost直流变换器设计了模糊控制器，给出了控制规则。最后通过仿真和实验验证了该方法的可行性和可靠性。

Abstract: Aiming at the neutral-point (NP) imbalance and the influence of the modulation strategy of the post-stage inverters on the neutral-point potential when the three-level Boost DC converter is used in the three-phase non-isolated grid-connected PV power generation inverters to start the voltage-building process, a fuzzy control strategy is proposed to realize the neutral-point potential balance at the power level of the three-level Boost DC converter. The duty cycle ratio of the switch of three-level Boost DC converter can be adaptively changed by using the fuzzy controller. Not only in the start-up process (when the DC bus is voltage-building), but also in the stable operation of grid-connected inverters, the voltages across output capacitors can be equalized and good dynamic and static performance is obtained. In this paper, a fuzzy controller is designed for three-level Boost DC converter, and the control rules are given. Finally, the feasibility and reliability of the method are verified by simulation and experiment.