三相并网逆变器比例复数积分电流控制技术

Current Regulation for Three-phase Grid-connected Inverters Based on Proportional Complex Integral Control

传统PI控制无法消除并网交流电流稳态误差,但关于稳态误差存在的根本原因相关文献描述较少。为揭示其本质,首先建立并网电流控制模型,然后通过叠加定理和频域分析得出结论:并网交流电流零稳态误差控制条件为:系统控制器在并网电流频率处具有无穷大增益,而PI控制不具有该特性。在该结论基础上,提出一种可消除并网交流电流稳态误差的比例复数积分(proportional complex integral,PCI)控制,给出一套控制器参数整定方法,并采用TMS320F2812 DSP实现系统的数字化控制。在理论分析的基础上进行仿真和实验研究,通过与PI控制对比验证PCI控制的有效性。

Proportional plus integral （PI） control is conventionally regarded as an unsatisfactory solution for ac grid-connected inverter systems because it cannot eliminate steady-state amplitude and phase errors. Unfortunately, few literatures discuss the nature of this problem. In order to clarify the point, the linear model for the grid current control is built, based on which a crucial conclusion is reached in virtue of the superposition theorem and frequency-domain analysis： Zero steady-state error control for grid-connected inverters is obtained on condition that the controller has the infinite gain at the excited frequency, which is not the case for PI control. Based on this conclusion, a novel proportional complex integral （PCI） control is proposed, which extends the conventional real domain control into the unconventional complex domain in a mathematic way. A step-by step parameter design procedure for PCI control is given. The control system is digitally implemented with TMS320F2812 DSP. Simulation and experiments are carried out based on the theoretical analysis, and the effectiveness of the proposed PCI control is verified by an apple to apple comparison with PI control.