Flyback switching power supply

Abstract

A flyback switch power supply connects NP1 heteronymous terminals in a transformer B to a power source, grounds second primary side winding NP2 heteronymous ends, and ensures that NP1 and NP2 are dual-wire parallel windings. Adding a capacitor C1, one end of C1 is connected to NP1 homonymous terminals, and the other end is connected to NP2 homonymous terminals. The secondary side winding uses a Q2 connection method that is the opposite to the prior art, and is controlled by a PWM signal controlled by another output voltage. The following effect is realized: when Q1 is connected, NP1 and NP2 are both excited, and there is artificial surplus energy; when Q1 is disconnected, the secondary side NS implements a rectified output voltage via Q2 on the basis of the output load requirements, and the leakage inductance and excess energy are non-destructively absorbed by NP2 via D1.

Description

TECHNICAL FIELD[0001]The present invention relates to the field of switching power supplies, and in particular, to a flyback switching power supply.BACKGROUND ART[0002]At present, switching power supplies have been extensively used. For applications with input power below 75 W and having no requirement on power factor (PF), flyback switching power supplies may have fascinating advantages: a simple circuit topology and a wide input voltage range. Since the number of components is small, the reliability of the circuit is relatively high, and the flyback switching power supply is widely used. For convenience, in many documents, the flyback switching power supply is also referred to as a flyback switching power supply, a flyback power supply, and a flyback converter. In Japan and Taiwan, it is also referred to as a flyback converter, a flyback switching power supply, and a flyback power supply. A common topology for AC / DC converters is shown in FIG. 0. The prototype of the figure is fro...

AI Technical Summary

Benefits of technology

The present invention provides a flyback switching power supply that has several technical benefits. Firstly, the leakage inductance between the primary and secondary-side windings is allowed to be relatively large, which reduces the need for a separate third winding for demagnetization. Secondly, the conversion efficiency is not reduced, and the losses during excitation and demagnetization are reduced. These benefits increase the bandwidth and improve the loop response of the power supply. Additionally, the bifilar winding is still used on the primary side, and the EMI performance is good. Overall, the technical effects of the present invention provide a more efficient, reliable, and versatile flyback switching power supply.

Problems solved by technology

This is because the input current is discontinuous and the ripple is relatively large, which has a relatively high requirement for a previous power supply device.

The output current is also discontinuous, and the ripple is large, which has a relatively high requirement for capacity of a subsequent filter capacitor.

The inductance of the primary-side winding is also relatively low, and it is often found that the calculated number of turns is insufficient for winding full a wire casing of a skeleton from left to right in a tiled manner.

At a low working voltage, the series connection causes the inductance to be excessively large, and the sandwich parallel connection scheme has to be used.

Consequently, losses are generated, which makes the efficiency of the switching power supply become low, causing the following problems:

Due to low internal resistance of the winding, it is induced that current caused by the voltages that are not equal is not small, causing losses and relatively large electromagnet interference.

The process is complicated, and the third winding formed by parallel connection by two windings also induces voltages that are not equal, causing losses and large electromagnetic interference.

In fact, for the common demagnetization by the third winding, the advantage is non-destructive demagnetization, and the efficiency is relatively high, but the choice of the wire diameter of the third winding is also a problem: a relatively small wire diameter is selected, and parallel winding with the primary-side winding is relatively troublesome, and the thin wire is easily pulled apart.

If a wire diameter the same as that of the primary-side winding is selected, costs are high.

The flyback switching power supply still has one shortcoming: the bandwidth of the switching power supply is insufficient, that is, the loop response is poor.

It is also very difficult to achieve 10 kHz.

However, as the jump frequency of the load increases, a control loop of the system cannot keep synchronization.

Images