摘要
文中提出一种背靠背型中性点钳位式(back-to-back neutral point clamped,BT-NPC)功率因数校正(power factor correction,PFC)电路,并设计二阶自适应滑模控制方法用于提高电路鲁棒性与降低电流谐波含量.首先,分析所提三电平 PFC 电路工作特性,推导该电路的等效模型及其模态扰动,并分析模态扰动量对其工作特性的影响;然后,结合高阶滑模理论与自适应控制两者的优点,设计二阶自适应滑模控制器,既使电路具有变结构控制的良好鲁棒性,又能最大限度的减小控制震颤.同时,基于电流带宽分析,设计比例谐振控制器补偿交流电流与工频相位,并设计基于扩张状态观测器的直流电压采样滤波方法,用于消除二倍频纹波造成的电流谐波影响.最后,基于 BT-NPC 电路,搭建220 V/50 Hz、1 kW/400 V的实验样机,实验结果验证所提变换器的可行性和控制方法的有效性.
Abstract
This paper proposes a back-to-back neutral point clamped(BT-NPC)power factor correction(PFC)circuit and designs a second-order adaptive sliding mode control method(SASMC)to enhance circuit robustness and reduce current harmonic content.First of all,by analyzing the operational characteristics and deriving the equivalent model of the three-level circuit along with its perturbations,the impact of perturbations on circuit operational characteristics is determined.Then,combining the advantages of high-order sliding mode theory and adaptive control,a second-order adaptive sliding mode controller is designed to provide the circuit with excellent robustness inherent in variable structure control while minimizing control chattering.Additionally,this paper analyzes the current bandwidth and designs a proportional resonant controller(PR)to compensate for AC current and grid phase.The DC voltage sample filter based on the extended state observer(ESO)is also designed to eliminate current harmonic effects caused by double-frequency ripple.Finally,the experimental prototype of the BT-NPC circuit is designed with a rated input of 220 V/50 Hz and an output of 1 kW/400 V.The experiment results have verified the feasibility of the proposed converter and the effectiveness of the control method.
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