Control strategies for low voltage DC residencial grids with constant power loads

This paper presents the design, control and analysis of a small DC residential grid supplying constant power loads. A DC/DC Buck converter is used to connect the main DC bus to the DC distribution grid. Constant power loads are DC/DC converters embedded in equipment, connected to the DC distribution grid, and considered to be operated at constant power, as usual in most electronic equipment. Two possible solutions to control the main DC/DC converter are designed and assessed: a linear controller and a novel non-linear controller based on the Lyapunov direct control method. The two control strategies are then compared, considering response time, overvoltage, and overall disturbance in the DC grid voltage. The obtained results show a better performance of the Lyapunov non-linear controller.