MULTI-LEVEL CONVERTER APPARATUS WITH EFFICIENCY IMPROVING CURRENT BYPASS

摘要

An apparatus includes a multi-level converter circuit (e.g., a neutral-point-clamped (NPC) converter circuit) configured to selectively couple first and second DC buses to a common node. The apparatus further includes first and second bypass circuits (e.g., diodes) coupling the common node to respective first and second ones of the DC busses. The first and second bypass circuits may be configured to provide unidirectional conduction paths between the common node and respective ones of first and second DC buses. In some embodiments, the multi-level converter circuit and the first and second bypass circuits are configured to support four quadrant operation, wherein the first and second bypass circuits conduct current in a first two quadrants and block current in a second two quadrants. The apparatus may be used, for example, as a rectifier and/or inverter in an uninterruptible power supply (UPS).