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

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Abstract
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.

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