Quasi-resonance control circuit of power supplier and its control method

Abstract

The present invention provides a quasi-resonant control circuit of power supplies and the control method . The present invention utilizes a control circuit formed by simple electric components and the control method to control a power transistor to conduct when the power transistor and a transformer is at zero voltage level, so as to reduce the switching loss when the conduction of the power transistor is conducted.

Description

【Technical field】 [0001] The present invention relates to a quasi-resonance control circuit and a control method for a power supply, in particular to conduction between a power transistor and a transformer contact at a zero-voltage level, thereby reducing switching losses of the power transistor. 【Background technique】 [0002] Quasi-resonant flyback switching power supplies have been widely used in the market in order to reduce switching loss and electromagnetic interference noise generated during conduction. Figure 1 is a conventional flyback quasi-resonant control circuit diagram, called RCC (Ring Choke Converter) flyback circuit topology, please refer to Figure 1, when the DC power supply B+ power supply is turned on, a small current is first provided through a resistor R1 to slowly Charging turns on the power transistor Q1, and the primary side current starts to flow to the flyback transformer T1, power transistor Q1 and current detection resistor R10 to the negative po...

AI Technical Summary

Problems solved by technology

Referring again to Figure 3, in order to achieve the operation of this quasi-resonant control circuit, the circuit is complicated, the number of parts is large, and the cost is relatively expensive.

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