MATLAB Implementation of BUCK Circuit with Dual-Loop Control Strategy

BUCK circuit is a common step-down DC-DC converter widely used in power electronic systems. This article demonstrates how to implement a dual-loop control scheme with constant current and constant voltage functionality for BUCK circuits using MATLAB. In BUCK circuit design, the dual-loop control strategy typically consists of an inner current loop and an outer voltage loop. The current inner loop regulates inductor current to ensure fast dynamic response, while the voltage outer loop maintains stable output voltage. This control approach enables smooth transitions between constant current and constant voltage modes, making it suitable for applications like battery charging and LED driving. For implementation, first establish the mathematical model of the BUCK circuit, including main circuit topology, PWM modulation module, and feedback network. Using MATLAB's Simulink tool to build the simulation model, PID controllers can be designed separately for both current and voltage loops. The reference signal for the current loop is typically determined by the output of the voltage loop, achieving automatic switching from constant current to constant voltage mode. During simulation, appropriate PI parameters must be configured to ensure system stability and dynamic performance. By observing waveforms of output voltage and inductor current, the effectiveness of the dual-loop control strategy can be verified. Additionally, load step-change tests can be incorporated to evaluate the system's disturbance rejection capability. For advanced implementation, modern control algorithms such as fuzzy control and sliding mode control can be explored within the dual-loop structure to further enhance BUCK circuit performance. MATLAB provides comprehensive toolboxes that facilitate algorithm validation and performance optimization for researchers. Key implementation aspects include using Simulink's Power Electronics toolbox for circuit modeling, implementing PID controllers with anti-windup features, and utilizing MATLAB's tuning algorithms for optimal parameter selection.