DCF Control Method Based on Digital Control and Its Stability Analysis

Abstract

This paper proposes a dual-current feedback (DCF) control scheme under digital control. The inverter system's model changes when operating in the digital domain. Through a detailed analysis of the model under digital control, a series of control block diagram derivations, and parameter determination using discrete-domain modeling methods, the study establishes the scheme's framework. The effectiveness of the theoretical analysis is validated through simulation experiments. The discrete-domain parameters derived from the theoretical analysis enable the DCF control scheme to achieve stable operation under digital control without requiring iterative adjustments. In contrast, continuous-domain parameters cannot ensure stable operation for the same scheme under digital control. Additionally, this control scheme can maintain stable operation even during grid voltage fluctuations, making it a suitable strategy for LCL-type grid-connected inverters.