Discrete-time sliding-mode-based digital pulse width modulation control of a boost converter

In this study, a non-linear digital control of a boost converter based on a sliding discrete-time approximation is presented. The control strategy follows a classical cascade regulation scheme with the inner loop consisting in a non-linear current-control based on discrete-time sliding mode, and the outer one being composed of a simple discrete-time proportional-integral (PI) controller for output voltage regulation. An analytical expression of the current control law is developed using a simplified discrete-time small-signal model of the boost converter. The discrete-time PI compensator is designed from a discrete-time small-signal parametric model of the inner loop obtained by linearisation around the desired equilibrium point. The proposed method is initially based on the notion of discrete-time sliding motion to eventually derive a pulse width modulation (PWM) controlled system. Thus, the reported approach can be categorised not only as a direct digital design technique for voltage regulation but also as a competitive method to design sliding-mode-based PWM controllers. Simulated and experimental results in a boost converter operating in continuous conduction mode verify the theoretical predictions.