Adaptive model-free sliding mode control for boost converter with flexibility to varying operating conditions

DC-DC boost converter (BC) is widely used in renewable energy systems and electric vehicles due to their high efficiency, compactness, and strong dynamic performance. However, input voltage fluctuations and parameter variations make maintaining stable operation challenging. Sliding Mode Control (SMC) offers high robustness but relies heavily on accurate system models, making it sensitive to uncertainties. In contrast, Model-Free Control (MFC) based on the ultra-local model (ULM) provides simplicity and robustness by estimating system behaviour in real time from input-output measurements. MFC is effective for minimum-phase systems but struggles with non-minimum-phase systems like BCs. To overcome this, an adaptive MFC-SMC (AMF-SMC) scheme is proposed, combining MFC and SMC principles. The approach uses ULM with a time-delay estimation (TDE) technique and an adaptive gain mechanism to enhance precision and responsiveness. Lyapunov analysis confirms uniform ultimate boundedness of the sliding surface. Comparative experiments demonstrate the proposed controller’s superior robustness, high accuracy, and chattering-free operation.