DC Voltage Regulation Bandwidth Enhancement Control in VSG based Bi-directional EV Charger

VSG-based bi-directional piles currently use DC/DC to regulate the intermediate DC bus voltage, and a gridside converter (VSG) to realize the charging and discharging power. However, there are steady-state deviations in the power under grid frequency perturbations, which cannot accurately track the commanded values. Thus, this paper proposes a new VSG bidirectional pile control architecture, i.e., a converter (VSG) is used to control the intermediate DC bus voltage, while DC/DC is used to accurately track the charging and discharging power. However, the VSG, as the inner loop of the DC voltage control outer loop, has an extremely slow dynamic response and cannot achieve voltage stabilization. At the same time, the conventional VSG has the problem that it is difficult to achieve fast power following and provide high inertia support at the same time, which limits the application of virtual synchronous machine in bidirectional charging pile to some extent. To this end, this paper further proposes to significantly increase the bandwidth of the VSG power loop by introducing feedforward channels and filters to eliminate the inherent oscillation poles of the VSG, thus significantly reducing the inner loop delay of the outer loop of the DC voltage, while achieving closed-loop regulation of the DC voltage.