Study on high robustness and fast dynamic response synchronous rectifier buck converter

Here, a novel control strategy combined by constant-frequency V² control and H_∞ robust control is proposed and tested in a buck converter. The control strategy not only demonstrates the fast transient response of ordinary V² control, but also shows strong robustness with different input conditions. The main drawbacks of V² control, such as high interference susceptibility and low input perturbation stability margin, can be improved by introducing H_∞ robust strategy into the controller design. During the analysis and design process, the original controlled system based on the V² control is modelled at first, then the H_∞ weighting functions are calculated according to the small-signal analysis of V² controlled buck converter. After that, the H_∞ robust compensator parameters based on constant-frequency V² control are calculated. Finally, a buck converter controlled by the proposed control strategy is built and tested, with 48 V input voltage, 12 V output voltage, and 120 W output power. The experimental results demonstrate the effectiveness of the converter with the proposed control, which also proves the proposed method has great potential for high robustness and fast dynamic response applications.