CN112039346A - Novel method for improving output power and efficiency of flyback power supply - Google Patents

Abstract

The invention provides a novel high-power and high-efficiency flyback power supply topology circuit to improve the output power and efficiency of the flyback power supply. Through this circuit, the output power of the switching power supply of the flyback topology can be increased, and the efficiency of the switching power supply can be improved, and the synchronous rectification circuit can be used in parallel at the same voltage output end, which solves the problem of the traditional flyback with built-in synchronous rectification at the same voltage output end. The parallel use of the rectifiers of the control IC has poor reliability, and even cannot be used. When doing high current output, it can reduce the secondary loss of the power supply and reduce heat generation.

Description

A Novel Method for Increasing Output Power and Efficiency of Flyback Power Supply

technical field

The invention belongs to the field of switching power supply circuit design, and relates to a novel method for improving the output power and efficiency of a flyback power supply.

Background technique

At present, in the design of switching power supply, the flyback topology structure uses one winding for the output of the same voltage of the output winding. The single-tube flyback can usually only achieve less than 150W, and the output current does not exceed 12A. If the output power is too large, or the output current is too large, Because the duty cycle is too large, the secondary rectifier conduction time is too long and the loss is too large, or in order to reduce the duty cycle, the primary switch tube will have a high reverse spike, resulting in a very high withstand voltage switch tube. Switches with high withstand voltage are expensive, and they are not easy to purchase due to the small amount of use in the market; the use of dual-tube flyback can solve the withstand voltage problem of the primary switch, but the same output voltage of a single winding cannot solve the secondary output current. large, resulting in large secondary rectification losses, especially for low-voltage and high-current products;

For high-current output power supplies, synchronous rectification is usually used in the design, but for rectifier tubes with built-in synchronous rectification control IC and field effect transistors, parallel connection cannot be supported, and a single tube cannot support excessive current.

The forward output can be used for high power, but the output requires a large energy storage inductor, which is costly and bulky; when using an LLC circuit, an additional LC resonant circuit is required for the input, which is complicated to debug and high cost.

SUMMARY OF THE INVENTION

In view of the above defects, we invented a new flyback power supply topology to improve the supported output power of the flyback power supply and solve the problem of reducing secondary losses when making large current output, especially to support the problem of synchronous rectification and parallel connection more reliably.

The topology of the switching power supply circuit adopts a double-tube flyback. The primary control switch tube is an N-type field effect transistor or IGBT. The S-pin source of the upper tube (IGBT is the e-pole) is connected to the upper end of the input winding of the transformer, and the D-pin drain of the lower tube is connected. (IGBT is the C pole) is connected to the lower end of the input winding of the transformer, the input driving signals of the upper tube and the lower tube are in the same sequence and phase. In this way, the reverse turn-off peak of the switch tube can be reduced, and the conventional withstand voltage switch tube can be used instead of the high-voltage switch tube. The voltage-resistant switch tube can support the primary to provide more power. At the same time, the main transformer coil of the switching power supply adopts the flyback winding method, and there is at least one secondary winding with the same output voltage. In parallel, this parallel architecture can support high-power and high-current output, and can better support the parallel problem of synchronous rectification in the same voltage output.

In this way, the output power and efficiency of the flyback power supply can be improved.

Description of drawings

In order to illustrate the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are required to be used in the description of the specific embodiments or the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. In the drawings, each element or section is not necessarily drawn to actual scale.

Figure 1 Schematic diagram of a new method for improving the output power and efficiency of a flyback power supply

Notes:

1.Q1: The upper tube of the switch tube 2.Q2: The lower tube of the switch tube

3.D1,D2: Diodes 4.D3,D4: Secondary rectifier diodes

5.Trans: Transformer 6.C1: Input filter capacitor

7.C2: Output filter capacitor 8.R1: Resistor (for current limit detection)

9.Vgs1: Upper tube drive signal 10.Vgs2: Lower tube drive signal

Remarks: D3 and D4 of this circuit structure are used to indicate secondary rectification, not specifically to use diodes, but also to use synchronous rectification current or other rectification devices; R1 and its position only indicate current limiting resistors, not essential components or designated positions.

Detailed ways

Embodiments of the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention. It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the usual meanings understood by those skilled in the art to which the present invention belongs.

It is to be understood that, when used in this specification and the appended claims, the terms "comprising" and "comprising" indicate the presence of the described features, integers, steps, operations, elements and/or components, but do not exclude one or The presence or addition of a number of other features, integers, steps, operations, elements, components, and/or sets thereof.

It is also to be understood that the terminology used in this specification of the present invention is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly dictates otherwise.

As used in this specification and the appended claims, the term "if" may be contextually interpreted as "when" or "once" or "in response to determining" or "in response to detecting" . Similarly, the phrases "if it is determined" or "if the [described condition or event] is detected" may be interpreted, depending on the context, to mean "once it is determined" or "in response to the determination" or "once the [described condition or event] is detected. ]" or "in response to detection of the [described condition or event]".

Example:

The topology of the switching power supply circuit adopts a double-tube flyback. The primary control switch tube is an N-type field effect transistor or IGBT. The S-pin source of the upper tube (IGBT is the e-pole) is connected to the upper end of the input winding of the transformer, and the D-pin drain of the lower tube is connected. (IGBT is the C pole) is connected to the lower end of the input winding of the transformer, the input driving signals of the upper tube and the lower tube are in the same sequence and phase. In this way, the reverse turn-off peak of the switch tube can be reduced, and the conventional withstand voltage switch tube can be used instead of the high-voltage switch tube. The voltage-resistant switch tube can support the primary to provide more power. At the same time, the main transformer coil of the switching power supply adopts the flyback winding method, and there is at least one secondary winding with the same output voltage. In parallel, this parallel architecture can support high-power and high-current output, and can better support the parallel problem of synchronous rectification in the same voltage output.

In this way, the output power and efficiency of the flyback power supply can be improved. Refer to Figure 1.

Figure 1 Schematic diagram of a new method for improving the output power and efficiency of a flyback power supply

Notes:

1.Q1: The upper tube of the switch tube 2.Q2: The lower tube of the switch tube

3.D1,D2: Diodes 4.D3,D4: Secondary rectifier diodes

5.Trans: Transformer 6.C1: Input filter capacitor

7.C2: Output filter capacitor 8.R1: Resistor (for current limit detection)

9.Vgs1: Upper tube drive signal 10.Vgs2: Lower tube drive signal

Remarks: D3 and D4 of this circuit structure are used to indicate secondary rectification, not specifically to use diodes, but also to use synchronous rectification current or other rectification devices; R1 and its position only indicate current limiting resistors, not essential components or designated positions.

For the methods provided by the embodiments of the present invention, for the purpose of brief description, for the parts not mentioned in the embodiments, reference may be made to the corresponding contents in the foregoing product embodiments.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. The scope of the invention should be included in the scope of the claims and description of the present invention.

Claims (4)

1. a novel high-power high-efficiency flyback power supply topology circuit improves the flyback power supply output power and the method for improving efficiency, it is characterized in that, The topology structure of the switching power supply circuit is a double-tube flyback, and the secondary output has the same output voltage and at least one output is rectified by the transformer double winding output and then connected in parallel. 2. according to claim 1, a kind of novel high-power high-efficiency flyback power supply topology circuit improves the method for flyback power supply output power and improving efficiency, it is characterized in that, The main transformer coil of the switching power supply adopts the flyback winding method, and there is at least one secondary winding with the same output voltage, which is a parallel winding method of two windings. 3. according to claim 1, a kind of novel high-power high-efficiency flyback power supply topology circuit improves the method for flyback power supply output power and improving efficiency, it is characterized in that, The input terminal adopts the double-tube flyback connection method, the switch tube is N-type field effect transistor or IGBT, the S-pin source of the upper tube (IGBT is the e-pole) is connected to the upper end of the input winding of the transformer, and the D-pin drain of the lower tube (IGBT is the e-pole) is connected to the upper end of the transformer input winding. C pole) connected to the lower end of the transformer input winding. 4. according to claim 1, a kind of novel high-power high-efficiency flyback power supply topology circuit improves the method for flyback power supply output power and improving efficiency, it is characterized in that, The input driving signals of the upper tube and the lower tube are in the same sequence and phase.

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