Minimum voltage type active clamp DC-DC converter

Abstract

The invention discloses a least-voltage type active clamping DC-DC converter. Circuit of the converter is formed as follows: Clamping capacitance cascaded to assistant inductance then is connected to assistant switch tube in parallel. The one end of above formed circuit is connected to a main switch tube and another end is connected to a diode, forming an invented basic converting circuit that replaces buck, boost, buckboost, Cuk, SEPIC and Zeta 6 kinds of basic converting circuit used in conventional converter. The invention has advantages of simple structure, low cost, and high working efficiency. Reverse recovery current of the diode is effectively restrained. Both of main and assistant switches of converter are zero voltage workable switches.

Description

technical field [0001] The present invention relates to DC-DC converters. Background technique [0002] figure 1 The circuit shown is connected by a switch tube M1 and a rectifier diode D2, and has three connection terminals labeled 1, 2, and 3 that are drawn out at the contact points. figure 2 The step-down converter (buck), boost converter (boost), step-up-step-down converter (buckboost) shown in a), b), c), d), e), and f) in Converter (Cuk), Sepic converter (SEPIC), Zeta converter (Zeta) and other basic conversion circuits in six conventional DC-DC converters, figure 2 Vin in each figure is the input voltage port of the converter, Vo is the output voltage port of the converter, L and L' are the inductors in the converter, and C is the capacitor in the converter. The disadvantage of the DC-DC converter composed of this basic conversion circuit is that the converter works as a hard switch. In the current continuous mode, the related loss cause...

AI Technical Summary

Problems solved by technology

The disadvantage of the DC-DC converter composed of this basic conversion circuit is that the converter works as a hard switch. In the continuous current mode, the related loss caused by the reverse recovery of the diode in the converter is very high. high current stress

Some converters adopt zero-voltage switching technology, which suppresses the reverse recovery current of the diode and realizes the zero-voltage switching operation of the main switch without increasing the voltage stress of the device. However, the auxiliary switching devices in the converter often do not work In the soft switching state; although the usual active clamp technology can realize the soft switching operation of the main switch and the auxiliary switch at the same time, the voltage stress of the main switch and the auxiliary switch increases a lot, and the voltage stress increases with the control duty cycle and load In addition, after the diode in the converter is turned off, the parasitic capacitance at both ends of the converter and the auxiliary inductance resonate to produce a serious voltage oscillation, and the voltage stress is large

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