Flyback power supply with power factor correction function

Abstract

The invention discloses a flyback power supply with a power factor correction function. The flyback power supply is used for a liquid crystal display product, and comprises an alternating current power supply, a filter circuit, a bridge rectification circuit, a bulk capacitor C1, a flyback transformer T1, an output rectification circuit, an output filter circuit, a metal oxide semiconductor (MOS) transistor Q1, a control chip, a feedback circuit and a power supply circuit. A power factor correction circuit is arranged between the bridge rectification circuit and the positive end of the bulk capacitor C1. By the power factor correction circuit, a power factor can be increased by 75 to 90 percent. A few electronic parts are involved. The flyback power supply is simple in structure and low in design and manufacture cost.

Description

technical field [0001] The invention relates to a flyback power supply, in particular to a flyback power supply with power factor correction function. Background technique [0002] Traditional liquid crystal display products do not have switching power supplies with power factor correction circuits, such as figure 1 As shown, the bridge rectifier circuit 02 output terminal (diode D3, D4 negative terminal) is directly connected with the large capacitor C 1 The power factor PF value of this circuit is only about 45%~55%. Due to the low power factor value, it flows into the large capacitor C 1 The peak pulse current at the positive terminal is relatively large, which generates a large number of odd harmonic components, causing interference and damage to the power grid, so it cannot be used for electrical products with an input power greater than 75W. For this reason, countries around the world have set relevant restrictions on the harmonic current input by general electrical ...

AI Technical Summary

Problems solved by technology

[0003] Currently, the power factor correction circuit 03 used in the switching power supply of liquid crystal display products, such as figure 2 As shown, but the power factor correction circuit 03 has a complex structure, uses a large number of electronic components, and the design cost is high, which makes the designed product less competitive in terms of price

For power adapter products larger than 75W, the internal space is often limited. If the existing power factor correction circuit 03 is used, due to the large number of electronic parts in the existing power factor correction circuit 03, it will make it more difficult to place the parts, thus It may cause the development cycle of power adapter products to be longer, and product reliability will often be reduced

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