Combined DC voltage control scheme for three-port energy router based on instantaneous energy balance

Abstract

DC voltage control is crucial for the multi-stage converter, because it contributes to reduce the DC capacitance and improve the reliability of the whole system. A combined control scheme, induding two parts, is proposed in this paper for controlling the two DC bus voltages respectively in the Energy Router. Firstly, the energy feed-forward control scheme is used to control the low voltage DC bus, which connects the dual active bridge, the inverter and the bidirectional DC/DC converter. Compared with the conventional feed-forward control scheme, the energy feed-forward control scheme considers the instantaneous energy changes of the inductors in the inverter and the DC/DC converter together. Secondly, for the high voltage DC bus, which is connected to the single-phase PWM rectifier, a new control scheme is proposed based on the energy balance relationship among the source, the load and the passive elements (the inductors and the capacitors). The proposed combined control scheme can improve obviously the transient performances of the two DC bus voltages. Simulation and experimental results have confirmed their superior performances.