Notice

Conventional voltage balancers for the bipolar low-voltage dc (LVDC) distribution system have been composed of multiple power stages, which degrades their power density and cost effectiveness. To minimize the power stages, this paper presents a single-stage voltage balancer with high-frequency isolation. This voltage balancer is based on three-level dual-active-bridge converter. Furthermore, for the proposed voltage balancer, an enhanced switching modulation using the two switching patterns and is proposed to fully balance the bipolar voltage level under unbalanced load condition and even for when one of the dc poles has no load. Besides, a closedloop control system can be implemented by using output voltage information and proportional-integral controllers. Finally, experimental results using a 3-kW laboratory prototype converter verify the effectiveness of the proposed voltage balancer.