O-Splines-Based Fixed-Frequency Integral Sliding-Mode Controller for PFC Rectifier

This paper proposes a fast-response sliding mode controller (SMC) for a semi-bridgeless boost converter under large and quick load fluctuations to ensure tight output voltage regulation and unity power factor correction (PFC) at the line side. In this sense, a novel approach for estimating the reference current profile is presented focusing on the real-time phasor estimation via the O-splines of the discrete-time Taylor-Fourier transform (DTTFT). This method allows for improving the computational efficiency and dynamic performance of the estimations of amplitude, frequency and phase of the network voltage used for the generation of the reference current profile. Several aspects of the controller design are discussed, including the choice of the sliding surface, the existence and stability conditions, and the implementation of an adaptive hysteresis band to fix the switching frequency and reduce zero-crossing distortion. Experimental results of a GaN-based prototype validate the theoretical predictions, exhibiting a PF close to 1 and a total harmonic distortion lower than 3.2% in presence of load changes of up to 50% and changes in the output voltage set point. Several comprehensive experimental comparisons between the proposed framework and the most widely used methods recently reported in the literature are accomplished in terms of transitory and steady-state responses. The robustness of the proposed control approach is experimentally demonstrated under sag conditions and a wide operating range of the input voltage.