System for providing working frequency for switching power supply converter

Abstract

The invention provides a system for providing working frequency for a switching power supply converter. The system comprises a feedback input circuit, a variable frequency and intermittent mode control circuit, a logical control circuit, an oscillator and a PWM (Pulse Width Modulation) generator, wherein the feedback input circuit is used for feeding a load state back into an integrated circuit through an optical coupling device and generating a first control signal; the variable frequency and intermittent mode control circuit is configured to receive the first control signal and generate a first output signal related to the frequency; the logical control circuit is configured to receive the first output signal and a sawtooth wave signal of the oscillator to form a second output signal; the oscillator is configured to receive the second output signal to control the charging and the discharging of a capacitor through current to form a third output signal (a sawtooth wave signal); and the PWM generator is configured to receive the second output signal and the third output signal to form a fourth output signal for switching on or off a power switch of the switching mode power supply converter. Through the system, the working frequency of a switching power supply is controlled to change along with the change of a load, so that the aim of reducing power consumption is achieved, and the efficiency of the system is increased.

Description

technical field [0001] The present invention provides a system for providing an operating frequency for a switching power converter. The invention is applied to the field of switching power supply. Background technique [0002] The high-frequency switching power supply operates at high frequency through MOSFET or IGBT, and its switching frequency is generally controlled in the range of 50 kHz to 100 kHz, which can achieve high efficiency and miniaturization. The increase of the switching frequency reduces the filter inductance and output capacitance, which is beneficial to the miniaturization of the switching power supply, but at the same time the loss of the switching tube and the transformer will increase accordingly. It is necessary to select a suitable switching tube and magnetic material to reduce the loss. resulting in an increase in cost. [0003] Taking the flyback switching power supply converter as an example, the power consumption mainly includes conduction loss...

AI Technical Summary

Problems solved by technology

A higher switching frequency can reduce the converter's requirements on the size of the energy storage components (inductance and capacitance), but when the load is lightened, using the same switching frequency will only reduce the ratio of actual power to apparent power, resulting in a larger Power loss

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