Digital control for a modular system of DC/DC converters for primary distribution system

In space applications, power subsystem is strongly dependent on the requirements from the other subsystems for each specific mission. Modular configuration of the power units would allow a reduction of the cost and a shorter time to market. This paper presents a control strategy of a modular power unit for a primary distribution system based on a droop digital control implemented on FPGA. Each power module has its own control stage, and there is no external communication among the modules. The proposed approach allows a proper regulation of the bus voltage, sharing the demand power among the modules connected to different power supplies (solar panel, battery). The key issue is that each module has a slightly different voltage reference that depends on the current provided to the load. The proposed system has been validated through simulations and with experiments in the laboratory. The results show the feasibility of the proposal, being the bus voltage within the specified limits, having an appropriate power distribution among the power units and having a stable dynamic response.