Research On Automatic Current And Voltage Sharing Of High Frequency Combined DC-DC Converters

Due to high power density, good dynamic performance, high reliability and high power rating, high frequency combined DC-DC converters are now one of the research focus in power electronics. Usually, it needs current or voltage sharing control loop to ensure equal current and voltage sharing, which makes the control system more complicated. In order to simplify the control, this paper researches on the topology and connection, all the work shown as follows:The mechanisms of natural current and voltage sharing are generalized, which contain two natural voltage sharing mechanisms in input series output parallel(ISOP) and input parallel output series (IPOS) combined DC-DC converters, as well as three natural current sharing mechanisms in input parallel output parallel(IPOP) combined DC-DC converters.Based on controlled current source characteristic paralleled current sharing mechanism, a new IPOP combined DC-DC converter is proposed. The operation principle is introduced. The steady current sharing and dynamic current sharing is analyzed, using large signal model and small signal model. It is concluded that equal current sharing can be guaranteed even with little parameter mismatches between modules. The natural current sharing mechanism is verified by both simulation and experiment.Based on voltage sharing mechanism of inductor volt-second balance, a new ISOP combined forward converter is also proposed. The derivation and operation principle is introduced. The voltage sharing is briefly analyzed, and is verified by simulation and experiment.