System Performance Optimization for Dual-Loop Dual-Variable Controlled Active Clamp Flyback Converter Using Decoupling Compensation Technique

Active clamp flyback (ACF) is a good candidate to be used in high frequency power adapter applications. For high performance, dual-loop dual-variable (DLDV) control strategy consists of voltage, current and period regulation loops is very suitable to be used in ACF converter. However, the complexed control framework makes the controller is hard to design, and which can affect the dynamic response of the system. Therefore, a cascade controller consists of a decoupling controller and digital controller is proposed for good stability and dynamic characteristic. The decoupling controller is used to eliminate the coupling effect between the output voltage and period regulation loop, and the digital controller is adopted to stabilize the system. To verify the effectiveness of the designed controller, simulation and experimental results based on a 65W 19.5V output ACF prototype are tested. By comparing with the non-decoupling controller, the designed controller has a faster dynamic and smaller voltage overshoot and undershoot in DLDV controlled ACF converter.