Simulation Evaluation of a Closed-Loop Control System for a Transformerless Modular DC-DC Converter

This paper presents the concept of closed-loop control for a modular high-step-down DC-DC converter. The analyzed converter uses four modules powered by an input capacitor divider. The system operates with a low duty cycle, so there are no short circuits of the input capacitors. In the analyzed control system, there is an output voltage controller, individual choke current controllers of modules, and controllers for input capacitors voltage balancing. А stable operation of the four-module system in a configuration with dual loop output voltage regulation and input voltage division control was demonstrated. The performance evaluation of the presented converter was carried out by the simulation in Matlab/Simulink. It is shown, that the modular converter can operate with a precisely balanced input voltages value. The obtained results show stable operation of the system, and the possibility of correcting the voltage sharing on the input capacitors by independently controlling the currents of the modules.