An Active Clamp Flyback Converter

Abstract

The invention discloses an active clamp fly-back converter, which comprises an active clamp circuit, an isolation feedback module and a controller. The converter is characterized in that the active clamp circuit consists of a main clamp circuit and an auxiliary clamp circuit; the isolation feedback module is used to detect a load current, generate a current detection signal related to the load current and transmit the current detection signal to the controller. The controller controls the working mode of the active clamp fly-back converter according to the current detection signal, wherein theconverter enters a double-clamp working mode when the current detection signal is higher than a predetermined value, and the converter enters a single-clamp working mode when the current detection signal reaches or is lower than the predetermined value. Compared with the prior art, by using mode switching, the efficiency of the circuit under heavy load is ensured, the efficiency when the load becomes light is improved, and the problem of oscillation in the circuit due to leakage inductance is eliminated; and by using a scheme of clamp switch tube driving transition, the system stability is improved, and the service life of the device is prolonged.

Description

Technical field [0001] The invention relates to the field of switching converters, in particular to an active clamp flyback converter. Background technique [0002] The traditional active clamping circuit is composed of a clamping switch tube and a clamping capacitor in series, which are connected in parallel to both ends of the main power switch tube or the primary winding of the main power transformer. A flyback converter with an active clamping circuit is generally called Active clamp flyback converter, active clamp flyback converter can not only absorb the leakage inductance energy, but also feed the leakage inductance energy back to the output terminal and realize the soft switching of the switch tube, which is improved compared to ordinary flyback converters. In order to improve efficiency, traditional active clamp flyback converters are favored by designers. [0003] The traditional active clamp flyback converter can realize the ZVS (Zero Voltage Switch, zero voltage switch...

AI Technical Summary

Problems solved by technology

The solution proposed by this patent can realize the ZVS of the main power switch S1 at light load, and solve the oscillation problem in the intermittent rest stage at the same time, but the leakage inductance oscillation is more obvious in the demagnetization stage of the transformer under heavy load, and the working waveform at heavy load is as follows image 3 shown

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