Resonant switch converter, control circuit and control method for automatic dead-time regulation of control circuit

Abstract

The invention discloses a resonant switch converter, a control circuit and a control method for automatic dead-time regulation of the control circuit. The resonant switch converter comprises an upper side switch tube, a lower side switch tube, a resonant tank circuit and the control circuit, wherein the control circuit comprises a slope sampling circuit, a slope judging circuit, a clock generating circuit, and a conduction moment control circuit; the slope sampling circuit generates slope signals representing the voltage slope at a common terminal between the upper side switch tube and the lower side switch tube; the slope judging circuit judges whether the slope signals are effective and generates slope judging signals; the time generating circuit generates clock signals; the conduction moment control circuit regulates the dead time between the upper side switch tube and the lower side switch tube according to the slope judging signals and the slope signals. Compared with the prior art, the resonant switch converter, the control circuit and the control method for automatic dead-time regulation of the control circuit can flexibly realize automatic regulation of the dead time, so as to ensure zero-voltage opening of the upper side switch tube and the lower side switch tube, and increase the system efficiency.

Description

technical field [0001] Embodiments of the invention relate to electronic circuits, and more particularly to resonant switching converters. Background technique [0002] In the resonant switching converter, under the action of the resonant tank circuit, the current flowing through the switching tube becomes a sine wave, so that the switching tube is turned on at a certain moment, thereby realizing zero-voltage or zero-current switching. [0003] Taking the half-bridge LLC resonant circuit as an example, usually by designing a suitable switching frequency and dead time, the voltage on the switch tube drops to zero before it is turned on, and it turns on when the current is negative. Before the switch tube is turned on, the current flows through the body diode of the switch tube, and turning on the switch tube at this time can realize zero-voltage turn-on. However, if the dead time is too large, the current of the half-bridge LLC resonant circuit will oscillate through zero, c...

AI Technical Summary

Problems solved by technology

However, if the dead time is too large, the current of the half-bridge LLC resonant circuit will oscillate through zero, causing capacitive switching

However, if the dead time is too small, as the inductance of the excitation inductor rises or the load current decreases, the switching frequency of the half-bridge LLC resonant circuit increases, and the excitation current decreases, so that the voltage on the switching tube is in the switching state. It cannot be reduced to zero before the tube is turned on, so that zero voltage turn-on cannot be achieved, which is not conducive to improving system efficiency

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