LCL滤波并网逆变器的分裂电容法电流控制

针对LCL滤波的并网逆变器电流控制时存在的系统稳定性和稳态误差与谐波失真等问题，提出了一种新的电流反馈控制技术。新的控制策略将LCL滤波器的电容按特定比例分成并联的前后两部分，通过测量中间电流并作为反馈信号控制逆变器输出，从而使受控系统的特性从三阶系统转换为一阶系统，控制性能得以改善，便于实现稳定误差和电流谐波失真的减小。本文给出了该控制策略的理论依据和实现方法，分析比较了新方法与传统控制方法的特性差异。通过对5kVA燃料电池逆变并网发电电源的试验验证了该控制策略。

Current Control for Grid-connected Inverters by Splitting the Capacitor of LCL Filter

This paper proposes a novel control strategy based on a new current feedback for grid-connected voltage source inverters (VSI) with an LCL-filter. The strategy “split” the capacitor of LCL-filter into two parts, and the current flowing between these two parts is measured and used as the feedback of a current regulator to stabilize and improve the system performances. By this way, the inverter control system is simplified from third-order to first-order, and the close loop control system can easily be optimized for minimum steady-state error and current harmonic distortion. The characteristics of the inverter system with the proposed controller are investigated and compared with the traditional strategy. Simulations results are provided, and the new current control strategy has been experimentally tested on a 5kW fuel cell inverter.