Optocoupler-based closed-loop hysteresis control for buck converter: experimental results

Abstract

This work experimentally evaluates a simplified closed-loop on-off (hysteresis) controller for a single-phase buck converter using an LM324 comparator and an optocoupler-based gate drive to the IRF830 MOSFET. The controller compares the output voltage against a reference and drives the switch in a binary manner, yielding variable-frequency regulation with low component count. Performance is assessed for DC-DC regulation and dynamic reference tracking under sinusoidal, triangular, and rectangular waveforms at 1 Hz and 60 Hz, as well as under input-voltage droop, load perturbations, and real-time changes in reference waveform. Results show envelope-accurate tracking with fast transients and bounded ripple across all tested conditions, including representative grid-frequency operation. The controller maintains stability and preserves waveform fidelity despite supply and load disturbances; edge transients observed for rectangular references at 60 Hz are consistent with expected output-capacitor dynamics and remain bounded. The findings support the suitability of analogue on-off hysteresis with optocoupler isolation as a low-complexity approach for applications requiring efficient DC-DC conversion and dynamic signal tracking, especially where cost, simplicity, and rapid response are prioritized.