CN219351543U

CN219351543U - Auxiliary source power supply circuit and switching power supply

Info

Publication number: CN219351543U
Application number: CN202223310314.0U
Authority: CN
Inventors: 钟青容; 赵问凤; 杨涛
Original assignee: Mornsun Guangzhou Science and Technology Ltd
Current assignee: Mornsun Guangzhou Science and Technology Ltd
Priority date: 2022-12-09
Filing date: 2022-12-09
Publication date: 2023-07-14
Anticipated expiration: 2032-12-09

Abstract

The utility model provides an auxiliary source power supply circuit which is used for outputting IC power supply by a switching power supply, and can maintain the IC power supply even under the condition of short circuit of output under the condition of small turn ratio of a flyback transformer and high output voltage. The circuit device comprises a capacitor C2, a rectifier diode D3, a capacitor C3, a triode Q2, a resistor R3, a voltage stabilizing tube ZD1 and a capacitor C4. When the primary MOS tube Q1 is conducted, the forward voltage of the main winding of the transformer T1 is utilized to charge the capacitors C2 and C3, the capacitor C2 and the capacitor C3 are connected in series for voltage division, the forward voltage of the transformer T1 is reduced, and then the power is supplied to the post-stage Q2 in a linear voltage-stabilizing mode for outputting. Compared with the traditional power supply mode, one path of winding is needed to be added on the transformer T1 for voltage reduction power supply, the design difficulty of the transformer is increased, the winding space of the transformer is occupied, and the cost is higher. The circuit can still maintain the output normal power supply under the condition of saving one auxiliary winding.

Description

Auxiliary source power supply circuit and switching power supply

Technical Field

The utility model belongs to the technical field of switching power supplies, and particularly relates to an auxiliary source power supply circuit and a switching power supply.

Background

In a conventional flyback switching power supply, the output usually uses an auxiliary winding of a transformer as a power supply circuit, and the step-down power supply is realized by designing the turn ratio of the transformer, so as to provide a proper working voltage for active devices such as a control IC, etc., and a schematic diagram of the auxiliary winding power supply circuit of the conventional transformer is shown in fig. 1.

The auxiliary source is supplied by the aid of the method that the transformer is provided with one more winding, the utilization rate of winding space of the transformer is low, the miniaturization design of the transformer is affected, the complexity of the transformer design is increased, winding space and safety distance are considered under the condition that the winding is increased, and the cost is relatively increased.

Therefore, the auxiliary source is designed without increasing the windings, and the application is of great significance.

Disclosure of Invention

In view of the above, the present utility model aims to provide an auxiliary source power supply circuit and a switching power supply, which can solve the above-mentioned drawbacks of the prior art at least to some extent.

As a first aspect of the present utility model, an embodiment of an auxiliary source power supply circuit is provided as follows:

an auxiliary source power supply circuit is applied to a switching power supply, the switching power supply comprises a transformer T1, a main power switching tube Q1 and a rectifying tube, the transformer T1 comprises a primary side winding and a secondary side winding, and one end of the primary side winding and the other end of the secondary side winding are homonymous ends; the input end of the switching power supply is connected with one end of the primary winding, the other end of the primary winding is connected with one end of the main power switching tube Q1, and the other end of the main power switching tube Q1 is coupled with the input ground end of the switching power supply; the output end of the switching power supply is connected with one end of the secondary winding, the other end of the secondary winding is connected with one end of the rectifying tube, the other end of the rectifying tube is connected with the output ground end of the switching power supply, and when the rectifying tube is conducted, current flows from the other end of the rectifying tube to one end of the rectifying tube; the auxiliary source power supply circuit includes: the capacitor C2 is characterized by comprising a capacitor C2, a diode D3, a capacitor C3 and a voltage stabilizing circuit, wherein one end of the capacitor C2 is an input end of the auxiliary source power supply circuit and is used for being connected with the other end of the secondary winding, the other end of the capacitor C2 is connected with an anode of the diode D3, a cathode of the diode D3 is connected with one end of the capacitor C3, one end of the capacitor C3 is coupled with an output end of the auxiliary source power supply circuit through the voltage stabilizing circuit, the other end of the capacitor C3 is a grounding end of the auxiliary source power supply circuit, and the voltage stabilizing circuit is used for stabilizing voltages at two ends of the capacitor C3 at a set value and then outputting power supply voltages through an output end of the auxiliary source power supply circuit.

Preferably, the voltage stabilizing circuit includes: resistor R3, voltage-stabilizing tube ZD1 and triode Q2, resistance R3 one end with triode Q2's collecting electrode is connected simultaneously electric capacity C3 one end, triode Q2's projecting pole is connected auxiliary source power supply circuit's output, voltage-stabilizing tube ZD 1's positive pole is connected auxiliary source power supply circuit's ground connection, voltage-stabilizing tube ZD 1's negative pole is connected simultaneously the resistance R3 other end with triode Q2's base.

Further, a capacitor C4 is further connected between the output end of the auxiliary source power supply circuit and the ground end thereof.

Further, the two ends of the capacitor C2 are also connected with a resistor R4 in parallel.

As a second aspect of the present utility model, an embodiment of a switching power supply is provided as follows:

the switching power supply comprises a transformer T1, a main power switching tube Q1 and a rectifying tube, wherein the transformer T1 comprises a primary winding and a secondary winding, and one end of the primary winding and the other end of the secondary winding are the same-name ends; the input end of the switching power supply is connected with one end of the primary winding, the other end of the primary winding is connected with one end of the main power switching tube Q1, and the other end of the main power switching tube Q1 is coupled with the input ground end of the switching power supply; the output end of the switching power supply is connected with one end of the secondary winding, the other end of the secondary winding is connected with one end of the rectifying tube, the other end of the rectifying tube is connected with the output ground end of the switching power supply, and when the rectifying tube is conducted, current flows from the other end of the rectifying tube to one end of the rectifying tube; the switching power supply further comprises an auxiliary source supply circuit as described in any of the first aspects above.

Preferably, the rectifying tube is a diode or a synchronous rectifying tube.

The working principle of the present application will be described with reference to specific embodiments, which are not described herein, and compared with the existing auxiliary winding power supply technology, the present utility model has the following beneficial effects:

the auxiliary source power supply circuit directly takes power from the secondary winding, obtains the reduced power supply voltage by serially dividing the two capacitors, outputs the reduced power supply voltage after being stabilized by the voltage stabilizing circuit, has simple circuit, can save one transformer winding under the condition of realizing normal power supply output, does not occupy the winding space of the transformer, has simple process and low cost, and has good application value.

Drawings

FIG. 1 is a schematic diagram of a conventional auxiliary winding power supply circuit for a transformer;

FIG. 2 is a schematic diagram of a switching power supply circuit including an auxiliary power supply circuit according to a first embodiment of the present utility model;

fig. 3 is a circuit diagram of a switching power supply including another specific schematic diagram of an auxiliary power supply circuit according to a first embodiment of the present utility model.

Detailed Description

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

It should be noted that the terms "comprising" and "having," and any variations thereof, as described in the specification and claims of this application are intended to cover a non-exclusive inclusion, for example, comprising a series of elements or unit circuits that are not necessarily limited to those elements or unit circuits explicitly listed, but may include elements or unit circuits that are not explicitly listed or inherent to such circuits.

In addition, embodiments and features of embodiments in this application may be combined with each other without conflict.

It will be understood that, in the description and in the claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element or "connected" to the other element through a third element.

First embodiment

The embodiment provides an auxiliary source power supply circuit, and fig. 2 is a circuit diagram of a switching power supply including a specific schematic diagram of the auxiliary source power supply circuit according to the first embodiment of the present utility model; fig. 3 is a circuit diagram of a switching power supply including another specific schematic diagram of an auxiliary power supply circuit according to a first embodiment of the present utility model. Referring to fig. 2 and 3, the auxiliary source power supply circuit of the present embodiment is applied to a switching power supply:

the switching power supply comprises a transformer T1, a main power switching tube Q1 and a rectifying tube, wherein the transformer T1 comprises a primary winding and a secondary winding, and one end of the primary winding and the other end of the secondary winding are the same-name ends; the input end of the switching power supply is connected with one end of a primary winding, the other end of the primary winding is connected with one end of a main power switching tube Q1, and the other end of the main power switching tube Q1 is coupled with the input ground end of the switching power supply; the output end of the switching power supply is connected with one end of the secondary winding, the other end of the secondary winding is connected with one end of the rectifying tube, the other end of the rectifying tube is connected with the output ground end of the switching power supply, and when the rectifying tube is conducted, current flows from the other end of the rectifying tube to one end of the rectifying tube.

Wherein, auxiliary source power supply circuit includes: the capacitor C2 is characterized by comprising a capacitor C2, a diode D3, a capacitor C3 and a voltage stabilizing circuit, wherein one end of the capacitor C2 is an input end of the auxiliary source power supply circuit and is used for being connected with the other end of the secondary winding, the other end of the capacitor C2 is connected with an anode of the diode D3, a cathode of the diode D3 is connected with one end of the capacitor C3, one end of the capacitor C3 is coupled with an output end of the auxiliary source power supply circuit through the voltage stabilizing circuit, the other end of the capacitor C3 is a grounding end of the auxiliary source power supply circuit, and the voltage stabilizing circuit is used for stabilizing voltages at two ends of the capacitor C3 at a set value and then outputting power supply voltages through the output end of the auxiliary source power supply circuit.

Specifically, the voltage stabilizing circuit comprises: resistor R3, regulator ZD1 and triode Q2, electric capacity C3 one end is connected simultaneously to resistance R3 one end and triode Q2's collecting electrode, and auxiliary source power supply circuit's output is connected to triode Q2's projecting pole, and auxiliary source power supply circuit's ground connection is connected to regulator ZD 1's positive pole, and the negative pole of regulator ZD1 connects resistance R3 other end and triode Q2's base simultaneously.

The voltage stabilizing principle of the voltage stabilizing circuit is as follows: the resistor R3 stabilizes the base voltage of the triode Q2 at a set value, for example, about 5.6V through the voltage stabilizing tube ZD1, and because the triode PN node has clamping characteristics, the emitter voltage of the triode Q2 is smaller than the base voltage of the triode Q2 by 0.7V, for example, about 4.9V (5.6V-0.7V), so that the voltage stabilizing circuit can stabilize the voltage at two ends of the capacitor C3 at a set value and then output the voltage through the output end of the auxiliary source power supply circuit.

Further, a capacitor C4 is further connected between the output end of the auxiliary source power supply circuit and the ground end thereof, and the filtering effect of the capacitor C4 can maintain the stability of the power supply voltage VCC output by the output end of the auxiliary source power supply circuit in this embodiment.

Further, the two ends of the capacitor C2 are also connected with the resistor R4 in parallel, and the discharge of the capacitor C2 can be accelerated by increasing the resistor R4, so that the output current capacity of the circuit can be increased.

The working principle of this embodiment is explained below in conjunction with fig. 2 as follows:

when the switching tube Q1 is turned on, the primary winding of the transformer T1 is excited, and the secondary winding induces electromotive force to rise "-" down "+", and the rectifier diode D2 is reversely cut off according to the same-name end relation; diode D3 switches on, and secondary winding forward power supply charges for electric capacity C2 and electric capacity C3, and electric capacity C2 and electric capacity C3 establish ties partial pressure, and the preferable electric capacity C2 is small, and electric capacity C3 is big, and most voltage partial pressure is on electric capacity C2, and after the forward voltage of transformer T1 was step down to electric capacity C3, output after stabilizing at a setting value with the voltage at electric capacity C3 both ends by voltage stabilizing circuit, need not to increase the winding, only need increase electric capacity C2, electric capacity C3, diode D3 and voltage stabilizing circuit, can realize the step-down power supply.

When the switching tube Q1 is turned off, the secondary winding of the transformer T1 is demagnetized, the induced electromotive force is up plus minus, the rectifying diode D2 is turned on, and the secondary circuit output capacitor Co is charged; the diode D3 is reversely cut off, the energy stored by the capacitor C3 maintains the voltage VCC at the output end of the auxiliary source power supply circuit, and when the Q1 is conducted next time, the capacitor C2 and the capacitor C3 are charged to supplement energy.

Second embodiment

Referring to fig. 2 and 3, the switching power supply of the embodiment includes a transformer T1, a main power switching tube Q1 and a rectifying tube, where the transformer T1 includes a primary winding and a secondary winding, and one end of the primary winding and the other end of the secondary winding are the same-name ends; the input end of the switching power supply is connected with one end of a primary winding, the other end of the primary winding is connected with one end of a main power switching tube Q1, and the other end of the main power switching tube Q1 is coupled with an input ground end; the output end of the switching power supply is connected with one end of the secondary winding, the other end of the secondary winding is connected with one end of the rectifying tube, the other end of the rectifying tube is coupled with the output ground end, and when the rectifying tube is conducted, current flows from the other end of the rectifying tube to one end of the rectifying tube; the switching power supply of this embodiment further includes any of the auxiliary source power supply circuits of the first embodiment.

Preferably, the rectifying tube is a diode or a synchronous rectifying tube.

In this embodiment, the secondary forward voltage is equal to the primary input voltage divided by the turn ratio, so when the primary secondary turn ratio of the transformer T1 is smaller, the secondary forward voltage is large, which is not suitable for direct power supply of the voltage stabilizing circuit, otherwise, the loss is large, and thus the voltage needs to be reduced, that is, the voltage at two ends of the capacitor C3 is output after the voltage stabilizing process by serially connecting the capacitor C2 diode D3 and the capacitor C3.

The above embodiments are only for aiding in understanding the inventive concept of the present application and are not intended to limit the present utility model, and any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art without departing from the principles of the present utility model should be included in the scope of the present utility model.

Claims

1. An auxiliary source power supply circuit is applied to a switching power supply, the switching power supply comprises a transformer T1, a main power switching tube Q1 and a rectifying tube, the transformer T1 comprises a primary side winding and a secondary side winding, and one end of the primary side winding and the other end of the secondary side winding are homonymous ends; the input end of the switching power supply is connected with one end of the primary winding, the other end of the primary winding is connected with one end of the main power switching tube Q1, and the other end of the main power switching tube Q1 is coupled with the input ground end of the switching power supply; the output end of the switching power supply is connected with one end of the secondary winding, the other end of the secondary winding is connected with one end of the rectifying tube, the other end of the rectifying tube is connected with the output ground end of the switching power supply, and when the rectifying tube is conducted, current flows from the other end of the rectifying tube to one end of the rectifying tube; the auxiliary source power supply circuit is characterized by comprising: the capacitor C2 is characterized by comprising a capacitor C2, a diode D3, a capacitor C3 and a voltage stabilizing circuit, wherein one end of the capacitor C2 is an input end of the auxiliary source power supply circuit and is used for being connected with the other end of the secondary winding, the other end of the capacitor C2 is connected with an anode of the diode D3, a cathode of the diode D3 is connected with one end of the capacitor C3, one end of the capacitor C3 is coupled with an output end of the auxiliary source power supply circuit through the voltage stabilizing circuit, the other end of the capacitor C3 is a grounding end of the auxiliary source power supply circuit, and the voltage stabilizing circuit is used for stabilizing voltages at two ends of the capacitor C3 at a set value and then outputting power supply voltages through an output end of the auxiliary source power supply circuit.

2. The auxiliary source power circuit of claim 1, wherein the voltage regulator circuit comprises: resistor R3, voltage-stabilizing tube ZD1 and triode Q2, resistance R3 one end with triode Q2's collecting electrode is connected simultaneously electric capacity C3 one end, triode Q2's projecting pole is connected auxiliary source power supply circuit's output, voltage-stabilizing tube ZD 1's positive pole is connected auxiliary source power supply circuit's ground connection, voltage-stabilizing tube ZD 1's negative pole is connected simultaneously the resistance R3 other end with triode Q2's base.

3. The auxiliary source power circuit of claim 2, wherein: and a capacitor C4 is also connected between the output end of the auxiliary source power supply circuit and the grounding end of the auxiliary source power supply circuit.

4. A secondary source supply circuit according to any one of claims 1 to 3, wherein: and the two ends of the capacitor C2 are also connected with a resistor R4 in parallel.

5. The switching power supply comprises a transformer T1, a main power switching tube Q1 and a rectifying tube, wherein the transformer T1 comprises a primary winding and a secondary winding, and one end of the primary winding and the other end of the secondary winding are the same-name ends; the input end of the switching power supply is connected with one end of the primary winding, the other end of the primary winding is connected with one end of the main power switching tube Q1, and the other end of the main power switching tube Q1 is coupled with the input ground end of the switching power supply; the output end of the switching power supply is connected with one end of the secondary winding, the other end of the secondary winding is connected with one end of the rectifying tube, the other end of the rectifying tube is connected with the output ground end of the switching power supply, and when the rectifying tube is conducted, current flows from the other end of the rectifying tube to one end of the rectifying tube; the method is characterized in that: the switching power supply further comprises an auxiliary source supply circuit as claimed in any one of claims 1 to 4.

6. The switching power supply of claim 5 wherein: the rectifying tube is a diode or a synchronous rectifying tube.