CN219659594U

CN219659594U - Switch power supply

Info

Publication number: CN219659594U
Application number: CN202320272326.4U
Authority: CN
Inventors: 马绵华
Original assignee: Mornsun Guangzhou Science and Technology Ltd
Current assignee: Mornsun Guangzhou Science and Technology Ltd
Priority date: 2023-02-21
Filing date: 2023-02-21
Publication date: 2023-09-08
Anticipated expiration: 2033-02-21

Abstract

The utility model discloses a switching power supply, which comprises an unstable voltage switching power supply module and a linear voltage stabilizing circuit; the input end of the non-stabilized switching power supply module is connected with the input voltage Vin, and the output end of the non-stabilized switching power supply module is connected with the input end of the linear voltage stabilizing circuit; the output end of the linear voltage stabilizing circuit is connected with the output end Vo of the switching power supply; when the voltage of the output end of the non-stabilized switching power supply module is smaller than the minimum stabilized voltage of the linear stabilized circuit, the voltage of the output end Vo is the voltage of the output end of the non-stabilized switching power supply module; when the voltage of the output end of the non-voltage-stabilizing switch power supply module is larger than the minimum voltage-stabilizing voltage of the linear voltage-stabilizing circuit, the linear voltage-stabilizing circuit stabilizes the voltage of the output end of the non-voltage-stabilizing switch power supply module, so that the voltage of the output end Vo is the voltage of the output end of the linear voltage-stabilizing circuit. The utility model has good load regulation rate and high efficiency when the load of the switching power supply is a medium load.

Description

Switch power supply

Technical Field

The utility model relates to the technical field of electronic circuits, in particular to a switching power supply.

Background

The non-voltage-stabilizing switch power supply has the advantages of simple circuit and low cost, is generally applied to occasions isolated from an input power supply, and can boost voltage and reduce voltage according to different requirements. As an open loop system, the output voltage changes with the input power voltage and the output current, when the input voltage is constant, the larger the output current is, the smaller the output voltage is, so the load regulation rate is poor, and especially in the application occasions of low-voltage output and larger required output current, the load regulation rate is more easily limited due to the load regulation rate difference. The conventional method is to add a linear voltage stabilizing circuit behind the non-voltage stabilizing switch power supply to output a completely stable voltage, so that the voltage stabilizing switch power supply is formed, the problem of poor load regulation is solved, the loss is greatly increased due to complete voltage stabilization, and the efficiency is greatly reduced.

Disclosure of Invention

In view of this, the present utility model provides a switching power supply, which effectively solves the problem of poor load regulation of an unstable switching power supply by combining an unstable switching power supply module with a linear voltage stabilizing circuit, and has high working efficiency when the load of the switching power supply is a medium load.

In order to achieve the above purpose, the present utility model adopts the following technical scheme:

the utility model provides a switching power supply, which comprises an unstable voltage switching power supply module and a linear voltage stabilizing circuit; the input end of the non-stabilized switching power supply module is connected with the input voltage Vin, and the output end of the non-stabilized switching power supply module is connected with the input end of the linear voltage stabilizing circuit; the output end of the linear voltage stabilizing circuit is connected with the output end Vo of the switching power supply;

when the voltage of the output end of the non-stabilized switching power supply module is smaller than the minimum stabilized voltage of the linear stabilized circuit, the voltage of the output end Vo is the voltage of the output end of the non-stabilized switching power supply module (the loss in the linear stabilized circuit is ignored at the moment); when the voltage of the output end of the non-voltage-stabilizing switch power supply module is larger than or equal to the minimum voltage stabilizing voltage of the linear voltage stabilizing circuit, the linear voltage stabilizing circuit stabilizes the voltage of the output end of the non-voltage-stabilizing switch power supply module, so that the voltage of the output end Vo is the voltage of the output end of the linear voltage stabilizing circuit.

Further, the non-stabilized switching power supply module is an open loop system, and the output voltage of the non-stabilized switching power supply module increases with the increase of the input voltage Vin and decreases with the increase of the output current.

Further, the minimum voltage stabilizing voltage of the linear voltage stabilizing circuit is larger than the output end voltage of the non-voltage stabilizing switch power supply module of the switch power supply in the heavy load state and smaller than or equal to the output end voltage of the non-voltage stabilizing switch power supply module of the switch power supply in the light no-load state.

Further, the non-stabilized switching power supply module includes: the driving circuit DR, the primary side main power circuit, the transformer and the rectifying circuit;

the driving circuit DR is electrically connected with the primary side main power circuit; the primary side main power circuit comprises a first input end, a second input end, a first output end, a second output end and a third input end, wherein the first input end is connected with an input voltage Vin, the second input end is connected with an input ground end GND, the first output end is connected with a homonymous end of a primary side winding Np of a transformer, and the second output end is connected with a heteronymous end of the primary side winding Np of the transformer; the secondary side of the transformer is connected with a rectifying circuit, and the output end of the rectifying circuit is used as the output end of the non-stabilized switching power supply module and is connected with a linear voltage stabilizing circuit.

Further, the primary side main power circuit includes: a capacitor C1, a capacitor C2, a switching tube Q1 and a switching tube Q2;

the first end of the capacitor C1 is connected with the drain electrode of the switching tube Q1, and the common end of the capacitor C1 is used as the first input end of the primary side main power circuit; the source electrode of the switching tube Q1 is connected with the drain electrode of the switching tube Q2, and the common end of the switching tube Q1 is used as a first output end of the primary side main power circuit; the driving circuit DR is connected between the grid electrode of the switching tube Q1 and the grid electrode of the switching tube Q2; the second end of the capacitor C1 is connected with the first end of the capacitor C2, and the common end of the capacitor C is used as the second output end of the primary side main power circuit; the second terminal of the capacitor C2 is connected to the source of the switching tube Q2, and the common terminal thereof is used as the second input terminal of the primary side main power circuit.

Further, the transformer includes a primary winding Np, a first secondary winding Ns1, and a second secondary winding Ns2.

Further, the rectifying circuit is a full-wave rectifying circuit and comprises a diode D1 and a diode D2; the anode of the diode D1 is connected with the homonymous end of the first secondary winding Ns1, and the anode of the diode D2 is connected with the heteronymous end of the second secondary winding Ns2; the cathode of the diode D1 is connected to the cathode of the diode D2, and the common terminal thereof is used as the output terminal of the rectifying circuit.

Further, the linear voltage stabilizing circuit includes: the switching tube Q3, the error amplifier U, the diode D3, the resistor R1, the resistor R2 and the resistor R3;

the drain electrode of the switching tube Q3 is used as the input end of the linear voltage stabilizing circuit to be connected with the output end of the rectifying circuit, the grid electrode is connected with the output end of the error amplifier U, the source electrode is respectively connected with the first end of the resistor R2, and the common end of the switching tube Q3 is used as the output end of the linear voltage stabilizing circuit to be connected with the output end Vo; the power supply end of the error amplifier U is the enabling end of the linear voltage stabilizing circuit and is connected with the output end of the rectifying circuit, the negative phase input end is connected with the output negative end of the switching power supply through the diode D3, the positive phase input end is respectively connected with the second end of the resistor R2 and the first end of the resistor R3, the second end of the resistor R3 is connected with the output negative end of the switching power supply, and the resistor R1 is connected between the power supply end and the negative phase input end of the error amplifier U.

The specific working principle of the present utility model will be described in the specific embodiment, and is not described herein. Compared with the prior art, the utility model has the beneficial effects that: according to the utility model, the non-stabilized switching power supply module and the linear voltage stabilizing circuit are combined to work, when the output voltage of the non-stabilized switching power supply module is higher than the working voltage of the linear voltage stabilizing circuit, the linear voltage stabilizing circuit can stabilize the output voltage of the non-stabilized switching power supply module, and the linear voltage stabilizing circuit does not play a role in stabilizing voltage in other working states; through the working mode, the problem of poor load regulation of the non-stabilized switching power supply can be effectively solved, when the load of the switching power supply is a medium load, the efficiency is greatly improved, and the circuit is simple in working principle and easy to design.

Drawings

Fig. 1 is a circuit block diagram of a switching power supply provided by the utility model.

Fig. 2 is a circuit block diagram of a switching power supply according to an embodiment of the present utility model.

Fig. 3 is a schematic circuit diagram of a switching power supply according to an embodiment of the present utility model.

Detailed Description

In order that the objects, technical solutions and advantages of the present utility model will become more apparent, the present utility model and its advantageous effects will be further described in detail below with reference to the detailed description and the accompanying drawings, it being understood that the detailed description is given herein for the purpose of illustrating the utility model only and not for the purpose of limiting the utility model.

Any feature disclosed in this specification (including any accompanying abstract and drawings), unless otherwise indicated, may be replaced by alternative features serving the same, equivalent or similar purpose. That is, each feature is one example only of a generic series of equivalent or similar features, unless expressly stated otherwise.

Electrical coupling, which means not only direct coupling, but also indirect coupling (i.e. other components may be connected between two electrically coupled objects), and includes coupling by induction or the like.

As shown in fig. 1, the present utility model provides a switching power supply, which includes an unregulated switching power supply module and a linear voltage stabilizing circuit; the input end of the non-stabilized switching power supply module is connected with the input voltage Vin, and the output end of the non-stabilized switching power supply module is connected with the input end of the linear voltage stabilizing circuit; the output end of the linear voltage stabilizing circuit is connected with the output end Vo of the switching power supply;

The non-stabilized switching power supply module is an open loop system, the output voltage of the non-stabilized switching power supply module increases along with the increase of the input voltage Vin, and decreases along with the increase of the output current; the minimum voltage stabilizing voltage of the linear voltage stabilizing circuit is larger than the output end voltage of the non-voltage stabilizing switch power supply module of the switch power supply in a heavy load state and smaller than the output end voltage of the non-voltage stabilizing switch power supply module of the switch power supply in a light no-load state.

As shown in fig. 2, the switching power supply provided in this embodiment includes: the power supply comprises an input capacitor Cin, an unstable voltage switching power supply module, a linear voltage stabilizing circuit and an output capacitor Co; wherein the non-stabilized switching power supply module includes: the driving circuit DR, the primary side main power circuit, the transformer and the rectifying circuit;

the input capacitor Cin is connected between the input voltage Vin and the input ground end GND, and the driving circuit DR is electrically connected with the primary side main power circuit; the primary side main power circuit comprises a first input end, a second input end, a first output end, a second output end and a third input end, wherein the first input end is connected with an input voltage Vin, the second input end is connected with an input ground end GND, the first output end is connected with a homonymous end of a primary side winding Np of a transformer, and the second output end is connected with a heteronymous end of the primary side winding Np of the transformer; the secondary side of the transformer is connected with a rectifying circuit, and the output end of the rectifying circuit is used as the output end of the non-stabilized switching power supply module and is connected with a linear voltage stabilizing circuit; the output capacitor Co is connected in parallel with the linear voltage stabilizing circuit and is connected between the output end Vo and the output negative end.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

As a specific embodiment of the switching power supply provided by the utility model, a schematic circuit diagram thereof is shown in fig. 3, and the switching power supply comprises: the power supply comprises an input capacitor Cin, an unstable voltage switching power supply module, a linear voltage stabilizing circuit and an output capacitor Co; wherein the non-stabilized switching power supply module includes: a driving circuit DR, a primary side main power circuit, a transformer and a full-wave rectifying circuit; the primary side main power circuit includes: a capacitor C1, a capacitor C2, a switching tube Q1 and a switching tube Q2; the transformer comprises a primary winding Np, a first secondary winding Ns1 and a second secondary winding Ns2; the full-wave rectifying circuit comprises a diode D1 and a diode D2; the linear voltage stabilizing circuit includes: the switching tube Q3, the error amplifier U, the diode D3, the resistor R1, the resistor R2 and the resistor R3;

the first end of the capacitor C1 is respectively connected with the input voltage Vin, the first end of the input capacitor Cin and the drain electrode of the switch tube Q1, and the second end of the capacitor C2; the second end of the capacitor C2 is respectively connected with the input ground end GND, the second end of the input capacitor Cin and the source electrode of the switching tube Q2; the driving circuit DR is connected between the grid electrode of the switching tube Q1 and the grid electrode of the switching tube Q2; the source electrode of the switching tube Q1 is connected with the drain electrode of the switching tube Q2, the connection point of the source electrode is connected with the homonymous end of the primary winding Np of the transformer, and the heteronymous end of the primary winding Np of the transformer is connected with the connection node of the capacitor C1 and the capacitor C2; the same-name end of a first secondary winding Ns1 of the transformer is connected with the anode of a diode D1, and the different-name end is connected with the same-name end of a second secondary winding Ns2 of the transformer and then is connected with an output ground end; the synonym end of the second secondary winding Ns2 is connected with the anode of the diode D2; the cathode of the diode D1 is connected with the cathode of the diode D2, and the common end of the diode D1 is connected with the input end and the enabling end of the linear voltage stabilizing circuit;

the drain electrode of the switching tube Q3 is used as the input end of the linear voltage stabilizing circuit to be connected with the cathode of the diode D1 and the common end of the cathode of the diode D2, the grid electrode is connected with the output end of the error amplifier U, the source electrode is respectively connected with the first end of the resistor R2, and the common end of the switching tube Q3 is used as the output end of the linear voltage stabilizing circuit to be respectively connected with the first end of the output capacitor Co and the output end Vo; the power supply end of the error amplifier U is the common end connection of the enabling end of the linear voltage stabilizing circuit and the cathode of the diode D1 and the cathode of the diode D2, the negative phase input end is connected with the output negative end of the switching power supply through the diode D3, the positive phase input end is respectively connected with the second end of the resistor R2 and the first end of the resistor R3, the second end of the resistor R3 is connected with the output negative end of the switching power supply, the resistor R1 is connected between the power supply end and the negative phase input end of the error amplifier U, and the second end of the output capacitor Co is connected with the output negative end.

In this embodiment, the driving circuit DR alternately turns on the switching transistors Q1 and Q2 with a duty ratio of about 50%.

The working principle of the embodiment is as follows:

the working mode of the switching power supply provided in this embodiment may be divided into the following four phases:

in the first stage, the driving circuit DR drives the switching tube Q1 to be turned on, the switching tube Q2 is turned off, the voltage 1/2Vin at the end of the voltage dividing capacitor C1 is applied to two ends of the primary winding Np, the polarity is positive and negative, the current of the primary winding Np is linearly increased, and meanwhile, the induced voltages of the first secondary winding Ns1 and the second secondary winding Ns2 are also positive and negative; at this time, the diode D1 is turned on, the diode D2 is turned off, the induced voltage of the first secondary winding Ns1 is output from the diode D1 to the enable end of the error amplifier U, and the induced voltage is stabilized by the resistor R1 and the diode D3 and then output a fixed voltage to be transmitted to the negative phase input end of the error amplifier U; the voltage of the output end Vo is divided by the resistor R2 and the resistor R3 and then is transmitted to the non-inverting input end of the error amplifier U, and the output end of the error amplifier U outputs a level signal to be transmitted to the grid electrode of the switching tube Q3 by comparing the voltage difference between the non-inverting input end and the negative phase input end. When the voltage of the diode D1 is larger than or equal to the minimum stable voltage of the linear voltage stabilizing circuit, the level signal of the output end of the error amplifier U negatively feeds back and adjusts the on and off of the switching tube Q3, and the voltage difference between the drain electrode and the source electrode of the switching tube Q3 is adjusted, so that the voltage of the output end Vo is stable, and the voltage of the output end Vo is the voltage of the output end of the linear voltage stabilizing circuit; when the voltage of the diode D1 is smaller than the minimum stable voltage of the linear voltage stabilizing circuit, the voltage of the non-inverting input end of the error amplifier U is always smaller than the voltage of the negative phase input end, so that the output end of the error amplifier U always outputs a low-level signal to drive the switching tube Q3 to be saturated and turned on, the voltage difference between the drain electrode and the source electrode of the switching tube Q3 is minimum, the voltage difference between the drain electrode and the source electrode is negligible, the voltage of the output end Vo is equal to the voltage of the diode D1, that is, the voltage of the output end Vo is the voltage of the output end of the non-stable voltage switching power supply module.

In the second stage, dead time exists between the driving of the switching tube Q1 and the driving of the switching tube Q2, when the switching tube Q1 is turned off and the switching tube Q2 is not turned on, the polarity of the primary winding Np is changed to be negative and positive, leakage inductance energy and part of excitation energy are returned to the capacitor C2 for storage by means of the capacitor C2 and the parasitic diode of the switching tube Q2, and meanwhile, the induced voltages of the first secondary winding Ns1 and the second secondary winding Ns2 are also changed to be negative and positive, so that the diode D2 is turned on, and the diode D1 is turned off. The induced voltage of the primary winding Np is outputted to the enabling end of the error amplifier U via the diode D2 by means of the second secondary winding Ns2, and the working principle of the linear voltage stabilizing circuit is similar to that of the first stage linear voltage stabilizing circuit, except that the second stage is that the diode D2 is turned on.

The third stage is similar to the first stage in operation principle, except that the driving circuit DR drives the switching tube Q2 to be turned on, the diode D2 to be turned on, and the diode D1 to be turned off.

The fourth stage is similar to the second stage in operation except that the fourth stage diode D1 is on and D2 is off.

The output voltage of the non-stabilized switching power supply module is higher when the output voltage of the non-stabilized switching power supply module is higher than the minimum stabilized voltage of the linear stabilized circuit, and the linear stabilized circuit starts to stabilize voltage, so that the output end Vo outputs a stable low voltage, namely the voltage of the output end of the linear stabilized circuit; the larger the output current is, the lower the output voltage of the non-voltage-stabilizing switch power supply module is, when the voltage of the output end of the non-voltage-stabilizing switch power supply module is lower than the minimum voltage stabilizing voltage of the linear voltage stabilizing circuit, the linear voltage stabilizing circuit does not stabilize the voltage, and at the moment, the voltage of the output end Vo is the voltage of the output end of the non-voltage-stabilizing switch power supply module, so that when the linear voltage stabilizing circuit detects large output current, the linear voltage stabilizing circuit does not stabilize the voltage, and the overall working efficiency of a switch power supply product is improved. According to the switching power supply provided by the utility model, the non-voltage-stabilizing switching power supply module and the linear voltage-stabilizing circuit are combined to work, when the voltage at the output end of the non-voltage-stabilizing switching power supply module is larger than or equal to the minimum voltage-stabilizing voltage of the linear voltage-stabilizing circuit, the linear voltage-stabilizing circuit starts to perform voltage-stabilizing operation, and the linear voltage-stabilizing circuit does not perform voltage-stabilizing effect in other states, so that the problem of poor load regulation of the non-voltage-stabilizing switching power supply is effectively solved, and the working efficiency is greatly improved especially when the load is a medium load.

The foregoing is merely a preferred embodiment of the present utility model, and it should be noted that the foregoing preferred embodiment should not be construed as limiting the present utility model, and that modifications and alterations can be made by those skilled in the art without departing from the spirit and scope of the utility model, and that modifications and alterations are also considered as protecting the transformer structure, and that the scope of the utility model shall be defined by the claims without further description.

Claims

1. The switching power supply is characterized by comprising an unstable voltage switching power supply module and a linear voltage stabilizing circuit; the input end of the non-stabilized switching power supply module is connected with the input voltage Vin, and the output end of the non-stabilized switching power supply module is connected with the input end of the linear voltage stabilizing circuit; the output end of the linear voltage stabilizing circuit is connected with the output end Vo of the switching power supply;

when the voltage of the output end of the non-stabilized switching power supply module is smaller than the minimum stabilized voltage of the linear stabilized circuit, the voltage of the output end Vo is the voltage of the output end of the non-stabilized switching power supply module; when the voltage of the output end of the non-stabilized switching power supply module is larger than or equal to the minimum stabilized voltage of the linear stabilized voltage circuit, the linear stabilized voltage circuit stabilizes the voltage of the output end of the non-stabilized switching power supply module, so that the voltage of the output end Vo is the voltage of the output end of the linear stabilized voltage circuit.

2. The switching power supply of claim 1 wherein the unregulated switching power supply module is an open loop system, the output voltage of the unregulated switching power supply module increasing with increasing input voltage Vin and decreasing with increasing output current.

3. The switching power supply of claim 1, wherein the minimum regulated voltage of the linear regulator circuit is greater than the output voltage of the unregulated switching power supply module when the switching power supply is in a heavy load state and less than or equal to the output voltage of the unregulated switching power supply module when the switching power supply is in a light idle state.

4. The switching power supply of claim 1 wherein said unregulated switching power supply module comprises: the driving circuit DR, the primary side main power circuit, the transformer and the rectifying circuit;

the driving circuit DR is electrically connected with the primary side main power circuit; the primary side main power circuit comprises a primary side main power circuit, a primary side winding Np, a primary side main power circuit and a secondary side main power circuit, wherein a first input end of the primary side main power circuit is connected with an input voltage Vin, a second input end of the primary side main power circuit is connected with an input ground end GND, a first output end of the primary side main power circuit is connected with a homonymous end of the primary side winding Np of the transformer, and a second output end of the primary side main power circuit is connected with a heteronymous end of the primary side winding Np of the transformer; the secondary side of the transformer is connected with the rectifying circuit, and the output end of the rectifying circuit is used as the output end of the non-stabilized switching power supply module and is connected with the linear voltage stabilizing circuit.

5. The switching power supply of claim 4 wherein said primary side main power circuit comprises: a capacitor C1, a capacitor C2, a switching tube Q1 and a switching tube Q2;

the first end of the capacitor C1 is connected with the drain electrode of the switching tube Q1, and the common end of the capacitor C1 is used as the first input end of the primary side main power circuit; the source electrode of the switching tube Q1 is connected with the drain electrode of the switching tube Q2, and the common end of the switching tube Q1 is used as a first output end of the primary side main power circuit; the driving circuit DR is connected between the grid electrode of the switching tube Q1 and the grid electrode of the switching tube Q2; the second end of the capacitor C1 is connected with the first end of the capacitor C2, and the common end of the capacitor C1 is used as the second output end of the primary side main power circuit; the second end of the capacitor C2 is connected with the source electrode of the switching tube Q2, and the common end of the capacitor C2 is used as the second input end of the primary side main power circuit.

6. The switching power supply of claim 5 wherein said transformer comprises a primary winding Np, a first secondary winding Ns1 and a second secondary winding Ns2.

7. The switching power supply according to claim 6, wherein the rectifying circuit is a full-wave rectifying circuit including a diode D1 and a diode D2; the anode of the diode D1 is connected with the homonymous end of the first secondary winding Ns1, and the anode of the diode D2 is connected with the heteronymous end of the second secondary winding Ns2; the cathode of the diode D1 is connected with the cathode of the diode D2, and the common end of the diode D1 is used as the output end of the rectifying circuit.

8. The switching power supply of claim 7 wherein said linear voltage regulator circuit comprises: the switching tube Q3, the error amplifier U, the diode D3, the resistor R1, the resistor R2 and the resistor R3;

the drain electrode of the switching tube Q3 is used as the input end of the linear voltage stabilizing circuit to be connected with the output end of the rectifying circuit, the grid electrode of the switching tube Q3 is connected with the output end of the error amplifier U, the source electrode of the switching tube Q is respectively connected with the first end of the resistor R2, and the common end of the switching tube Q3 is used as the output end of the linear voltage stabilizing circuit to be connected with the output end Vo; the power supply end of the error amplifier U is the enabling end of the linear voltage stabilizing circuit and the output end of the rectifying circuit, the negative phase input end is connected with the output negative end of the switching power supply through a diode D3, the positive phase input end is respectively connected with the second end of the resistor R2 and the first end of the resistor R3, the second end of the resistor R3 is connected with the output negative end of the switching power supply, and the resistor R1 is connected between the power supply end and the negative phase input end of the error amplifier U.