Low forward voltage rectifier using capacitive current splitting

摘要

A Low Forward Voltage Rectifier (LFVR) circuit includes a bipolar transistor, a parallel diode, and a capacitive current splitting network. The LFVR circuit, when it is performing a rectifying function, conducts the forward current from a first node to a second node provided that the voltage from the first node to the second node is adequately positive. The capacitive current splitting network causes a portion of the forward current to be a base current of the bipolar transistor, thereby biasing the transistor so that the forward current experiences a low forward voltage drop across the transistor. The LFVR circuit sees use in as a rectifier in many different types of switching power converters, including in flyback, Cuk, SEPIC, boost, buck-boost, PFC, half-bridge resonant, and full-bridge resonant converters. Due to the low forward voltage drop across the LFVR, converter efficiency is improved.

主权项

1. A switching power converter circuit comprising:
a first capacitor having a first terminal and a second terminal; a second capacitor having a first terminal and a second terminal, wherein the first terminal of the second capacitor is coupled to the first terminal of the first capacitor at a first node; a bipolar transistor having a base, a collector, and an emitter, wherein the collector is coupled to the second terminal of the second capacitor, and wherein the base is coupled to the second terminal of the first capacitor; a diode having an anode and a cathode, wherein the anode is coupled to the collector of the bipolar transistor, and wherein the cathode is coupled to the emitter of the bipolar transistor at a second node; a first inductor having a first terminal and a second terminal, wherein the first terminal of the first inductor is coupled to the collector of the bipolar transistor; and a second inductor having a first terminal and a second terminal, wherein the first terminal of the second inductor is coupled to the base of the bipolar transistor, and wherein the second terminal of the second inductor is coupled to the second terminal of the first inductor at a third node.