A Fixed Frequency Duty-Ratio Based Digital Sliding-Mode Controller for DC–DC Buck Converter

摘要

The hysteresis modulation (HM) based sliding mode control (SMC) implementation results in variable frequency, where the converter's operating frequency cannot be measured accurately. This will have a negative impact on circuit component and filter design. Furthermore, it is sensitiveto the disturbances and the parameter uncertainties. To maintain constant switching frequency during line and load regulation, a duty-ratio (DR) based sliding-mode (SM) control approach is proposed in this paper and applied to a DC–DC buck converter. The translation of the SM controllaw for HM and DR scheme implementation by using field programmable gate array (FPGA) for DC–DC buck converter is illustrated. A simple and self-explanatory design and implementation procedure are also addressed. The performance and robustness of the proposed DR-based SM controllersare validated by both simulation results using MATLAB/Simulink and experimental results. The robustness of the SM controller is tested at various operating conditions and compared the results with HM-based SM and conventional linear controller.