Advanced control circuit for intermediate bus converter

Power systems employing intermediate bus architecture (IBA) are lower cost and superior power quality solution versus the centralized power supply or distributed isolated DC-DC converters. The advantage of IBA depends heavily on highly efficient and power dense unregulated intermediate bus converter (IBC). This isolated IBC generates intermediate bus voltage in the range from 8 V to 14 V to supply local point-of-load regulators. The paper describes advanced control approach for the intermediate bus converter specifically addressing its key requirements. The new controller includes load current dependent off time control for improved efficiency, special means to address potential oscillating of synchronous self-driven MOSFET rectifiers and frequency control circuit to minimize the size of output inductor. Efficiency and performance improvement of IBC using described controller is verified by test results of the module with nominal input voltage 48 V and output power up to 600 W.