Performance enhancement for digital implementations of resonant controllers

Resonant control is one of the highest performance alternatives for ac current/voltage control. The implementations based on two integrators are a widely employed choice in order to provide frequency adaptation to these regulators without substantial computational burden. However, the discretization of these schemes causes a significant error both in the resonant frequency and in the phase lead provided by the delay compensation. Therefore, perfect tracking is not assured, and stability is compromised at high frequencies or low sampling periods. This paper contributes solutions for both problems without adding a significant resource consumption. Furthermore, the previously proposed approaches for calculating the leading angle are analyzed, and a novel expression with superior performance is contributed. Experimental results obtained by means of a laboratory prototype corroborate the theoretical analysis and the improvement achieved by the proposed discrete-time implementations.