Analysis of abnormal phenomena caused by synchronous rectifiers in a paralleled converter system

Problems of synchronous rectification in a parallel-module DC-DC power converter system are described. These include excessive power dissipation due to the bidirectional current flow capability of MOSFETs and abnormal oscillation due to the cross coupling of the MOSFETs used as synchronous rectifiers. The abnormal oscillation, which causes excessive voltage stress, is analyzed; the results of which are subsequently confirmed by experiment. Methods for solving the abnormal oscillation problem are discussed.