Robust Control for Enhanced Dynamic Performance of CRM-Based Active Power Decoupling Circuit

The inherent tendency of single-phase grid-connected ac–dc converters is to produce double-line-frequency ripple at the dc link. A buck-based active power decoupling (APD) converter is employed to solve this issue of double-line-frequency ripple. By operating the APD converter with variable switching frequency, a critical condition mode (CRM) is achieved, which ensures soft switching of both the switches of APD converter. However, high-attenuation-based digital filters in both voltage and current loops are necessary in variable-switching-frequency-based control, which introduces new dynamics in the control loop. This limits the ability of the controller to rapidly adjust the decoupling capacitor voltage with change in output power. In this article, a novel control method is proposed for the APD converter, which entitles the design of a faster decoupling control, while ensuring the system stability and efficiency during dynamic periods. Although the proposed control results in higher robustness and improved transient response, the original dynamics of the system remain unaffected. The steady-state and dynamic performance improvement results with the proposed control of the CRM-operated APD converter are validated through simulation and experimental results.