Continuous Sliding Mode Control of Buck Converter with Constant Switching Frequency

In this paper, a novel continuous sliding mode (SM) control approach is proposed to address the two problems of chattering and non-constant switching frequency for buck converters. Instead of using the commonly used sub-optimal algorithm and hysteresis modulation (HM) method, a continuous SM controller is designed on the basis of the averaging model of buck converters to solve the chattering problem and to achieve control continuity. In phase plane, the control performance is analyzed around the equilibrium point simultaneously, leading to a variable hysteresis width for HM. The influence relationship of the switch frequency with the hysteresis width and controller parameter of buck converters is investigated. Simulations validate the proposed approach.