Research on dual closed-loop PI control strategy for supercapacitor energy storage and release converters

To address the efficient energy storage and release requirements of supercapacitors in energy storage systems, a dual-loop PI control strategy based on a bidirectional DC-DC converter is proposed, featuring a voltage outer loop and a current inner loop. By establishing a small-signal model of the converter, the system stability under supercapacitor charge-discharge conditions is analyzed, and PI controller parameters are designed based on frequency-domain characteristics. The voltage outer loop dynamically regulates the DC bus voltage, while the current inner loop accurately tracks charging and discharging current commands, effectively suppressing voltage fluctuations caused by load variations. Simulation results demonstrate that the dynamic performance achieves seamless mode switching between energy storage and release within 0.5 seconds, with a response speed improvement of 40%. The disturbance rejection capability ensures that bus voltage fluctuations are limited within ±10% under 80% load step disturbances. This strategy significantly enhances system robustness and energy conversion efficiency, providing a reliable control solution for high-fluctuation renewable energy generation scenarios.