Transient Response and Stability Improvement of Buck Converter by Using Digital Predictive V2C Peak Control

V² control is widely used in Buck converter due to its good transient response. However, its control performance is highly dependent on the value of the equivalent series resistance of the output capacitor, which may even lead to system instability. To overcome this issue, a digital predictive V²C peak control algorithm is proposed. First, the system structure of buck converter based on digital predictive V²C control is introduced. The control object of the inner loop is the weighted value of inductor current and output voltage instead of only output voltage. Then, according to the geometric characteristics of inductor current and output voltage ripples, the predictive V²C peak control algorithm is proposed. It can eliminate the inner loop feedback voltage disturbance within two switching cycles and effectively avoid subharmonic oscillation. Furthermore, the small-signal model analysis of Buck converter with the proposed algorithm is carried out to derive the open-loop transfer function, which guides the optimal design of the outer loop controller. Finally, simulation results prove the proposed algorithm has improved transient response and stability than V² control.