New NPC multi-level four-quadrant DC-DC converter controlled by the integrated-voltage-control method

A switching mode DC-DC converter controlled by the integrated-voltage-control method works stably and has no steady state error and a quick response time. We propose a new NPC (neutral-point-clamped) multi-level four-quadrant DC-DC converter controlled by the integrated-voltage-control method. It consists of eight hysteresis comparators driven by an error voltage integrator. The working region is divided into eight regions and one of eight power transistors driven by one of eight comparators to on/off in each prearranged region. The neutral-point voltage can also be kept at a constant value by a new restrain control scheme.