Dual-Buck Half-Bridge Voltage Balancer

Abstract

Micro-dc grid is a novel power system focused on the development of renewable resources. However, two-wire transmitting power mode is generally accepted in a micro-dc grid, which is usually not suitable for the requirements of the input voltage levels of different power converters and loads. In order to meet the requirements, a half-bridge voltage balancer was introduced in a micro-dc grid, which can convert a two-wire mode into a three-wire mode in a micro-dc grid via a neutral line. However, the shoot-through problem existing in bridge-type converters degrades the reliability of the voltage balancer. In this paper, a dual-buck half-bridge voltage balancer and a control strategy are proposed, which can avoid the shoot-through problem. The small-signal model of the voltage balancer is derived for designing the control parameters and the current relationships of the inductors; the capacitors and the unbalanced loads are analyzed particularly. Finally, a prototype, which can deal with 2-kW unbalance ability, is built to verify that the proposed voltage balancer may have a good ability of balancing the voltage by building a neutral line.