CN116154724A

CN116154724A - Short-circuit protection circuit and power conversion circuit

Info

Publication number: CN116154724A
Application number: CN202211667771.7A
Authority: CN
Inventors: 黄诗源
Original assignee: Shenzhen Megmeet Welding Technology Co ltd
Current assignee: Shenzhen Megmeet Welding Technology Co ltd
Priority date: 2022-12-23
Filing date: 2022-12-23
Publication date: 2023-05-23

Abstract

The application discloses short-circuit protection circuit and power conversion circuit, this short-circuit protection circuit includes: a power supply circuit; the control circuit receives the first power supply provided by the power supply circuit and determines the transmission mode of the control signal according to the first power supply; the output circuit receives the control signal sent by the control circuit and sends the control signal to the load circuit, so that when the load circuit is short-circuited, the voltage of the first power supply is gradually reduced to be lower than a set voltage threshold value periodically and then gradually increased, and when the voltage of the first power supply is lower than the set voltage threshold value, the control circuit does not send the control signal to the output circuit, and when the voltage of the first power supply is higher than the set voltage threshold value, the control signal is sent to the output circuit. The short-circuit protection circuit in the application can be repeatedly disconnected when the load circuit is short-circuited, and the output provided for the load circuit is turned on, so that the short-circuit loss is effectively reduced, and the configuration requirements and the working temperature of all devices in the short-circuit protection circuit are reduced.

Description

Short-circuit protection circuit and power conversion circuit

Technical Field

The present disclosure relates to the field of electronic devices, and in particular, to a short-circuit protection circuit and a power conversion circuit.

Background

Nowadays, among common faults of each functional circuit of an electrical device, a short-circuit fault is generally included, so how to provide effective short-circuit protection for each functional circuit is one of key issues of not opening the circuit design field.

However, in the existing circuit for providing short-circuit protection, current sampling is usually implemented by adopting a resistor, so that when a short circuit occurs, the short-circuit current becomes extremely large, a large short-circuit loss is caused, and the short-circuit power of the circuit is continuously maintained, so that a high configuration requirement is provided for each device in the circuit, and the corresponding working temperature is also high, thereby adversely affecting the service life of each device.

Disclosure of Invention

The application provides a short-circuit protection circuit and power conversion circuit, and this short-circuit protection circuit can solve the short-circuit loss of the short-circuit protection circuit among the prior art great, and circuit short-circuit power will keep continually, therefore has put forward higher configuration demand to each device in the circuit, and corresponding operating temperature is also higher to the problem of adverse effect has also been brought to the life of each device.

In order to solve the technical problems, one technical scheme adopted by the application is as follows: there is provided a short-circuit protection circuit, wherein the short-circuit protection circuit includes: a power supply circuit; the control circuit is connected with the power supply circuit to receive the first power supply provided by the power supply circuit and determine the transmission mode of the control signal according to the first power supply; the output circuit is connected with the power supply circuit and the control circuit and is used for being connected with an external load circuit, receives a control signal sent by the control circuit and sends the control signal to the load circuit, so that when the load circuit is short-circuited, the voltage of the first power supply is gradually reduced to be lower than a set voltage threshold periodically and then is gradually increased to be higher than the set voltage threshold; wherein the control circuit will not send a control signal to the output circuit when the voltage of the first power supply is below the set voltage threshold and send a control signal to the output circuit when the voltage of the first power supply is above the set voltage threshold.

The power supply circuit comprises a first resistor and a first capacitor, wherein the first end of the first resistor is used for being connected with an external first power supply, the second end of the first resistor is connected with the output circuit, the control circuit and the first end of the first capacitor, the second end of the first capacitor is connected with the control circuit, and the first resistor receives a second power supply provided by the first power supply so as to store or discharge the second power supply through the first resistor and the first capacitor, so that the second power supply is converted into the first power supply.

Wherein the resistance value of the first resistor is 10Ω -150Ω.

The output circuit comprises a driving transformer, the driving transformer comprises a primary winding and a secondary winding which are mutually and magnetically connected, a first end of the primary winding is connected with the power supply circuit, a second end of the primary winding is connected with the control circuit, a first end and a second end of the secondary winding are respectively used for being connected with the first end and the second end of the load circuit, and the driving transformer receives a control signal sent by the control circuit and sends the control signal to the load circuit after converting the control signal.

The secondary winding comprises a first secondary winding and a second secondary winding, the load circuit comprises a first sub-load circuit and a second sub-load circuit, the first end and the second end of the first secondary winding are respectively used for connecting the first end and the second end of the first sub-load circuit, the first end and the second end of the second secondary winding are respectively used for connecting the first end and the second end of the second sub-load circuit, and the driving transformer receives a control signal sent by the control circuit and sends the control signal to the first sub-load circuit after converting the control signal.

The output circuit further comprises a first diode, the first end of the second sub-secondary winding is connected with the first end of the first diode, the second end of the second sub-secondary winding is connected with the second end of the second sub-load circuit, and the second end of the first diode is connected with the first end of the second sub-load circuit.

The output circuit further comprises a second resistor, the first end of the first sub-secondary winding is connected with the first end of the second resistor, the second end of the first sub-secondary winding is connected with the second end of the first sub-load circuit, and the second end of the second resistor is connected with the first end of the first sub-load circuit.

The control circuit further comprises a driving chip and a first switching tube, the driving chip is connected with the power supply circuit and the first switching tube, the first switching tube is connected with the power supply circuit and the output circuit, the driving chip receives a first power supply provided by the power supply circuit, determines a transmission mode of a control signal according to the first power supply, and transmits the control signal to the first switching tube when determining to transmit the control signal, so that the control signal is transmitted to the output circuit after being regulated by the first switching tube.

In order to solve the technical problem, another technical scheme adopted by the application is as follows: there is provided a power conversion circuit, wherein the power conversion circuit includes: the buck-boost topology circuit is connected with the short-circuit protection circuit and is used for connecting an external second power supply and the load circuit, receives a third power supply provided by the second power supply and a control signal sent by the short-circuit protection circuit, and performs voltage conversion on the third power supply according to the control signal so as to provide the third power supply after voltage conversion for the load circuit; wherein the short-circuit protection circuit is any one of the above-described short-circuit protection circuits.

The buck-boost topology circuit comprises a second switch tube, an inductor, a second diode, a third resistor and a second capacitor; the first end of the second switch tube is connected with the first end of the second power supply, the second end of the second switch tube is connected with the first end of the short-circuit protection circuit, the third end of the second switch tube is connected with the second end of the short-circuit protection circuit, the first end of the inductor and the second end of the second diode, the second end of the inductor is connected with the third end of the short-circuit protection circuit, the first end of the third resistor, the first end of the load circuit, the second end of the second capacitor and the fourth end of the short-circuit protection circuit, the first end of the second diode is connected with the second end of the load circuit, the first end of the second capacitor and the fifth end of the short-circuit protection circuit, and the second end of the third resistor is connected with the second end of the second power supply.

The beneficial effects of this application are: compared with the prior art, when the control circuit in the short-circuit protection circuit receives the first power supply provided by the power supply circuit, the transmission mode of the control signal can be determined according to the first power supply, the output circuit receives the control signal transmitted by the control circuit and transmits the control signal to the load circuit, so that when the load circuit is in short circuit, the voltage of the first power supply is gradually reduced to be lower than a set voltage threshold value and then gradually increased to be higher than the set voltage threshold value, when the voltage of the first power supply is lower than the set voltage threshold value, the control circuit does not transmit the control signal to the output circuit, and when the voltage of the first power supply is higher than the set voltage threshold value, the control circuit transmits the control signal to the output circuit, so that when the load circuit is in short circuit, the output provided to the load circuit can be repeatedly disconnected and then opened, the short-circuit protection circuit works intermittently, the configuration requirements and the working temperature of all devices in the short-circuit protection circuit and the load circuit are reduced, and adverse effects on the service life of all devices are avoided. After the short circuit is relieved, the short circuit protection circuit can automatically and timely recover normal power supply to the load circuit, and the influence caused by the short circuit is minimized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:

FIG. 1 is a schematic diagram of a first embodiment of a short-circuit protection circuit of the present application;

FIG. 2 is a schematic diagram of a second embodiment of the short-circuit protection circuit of the present application;

FIG. 3 is a schematic diagram of a first embodiment of a power conversion circuit of the present application;

fig. 4 is a schematic structural diagram of a second embodiment of the power conversion circuit of the present application.

Detailed Description

The following description of the technical solutions in the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

The terms "first," "second," "third," and the like in this application are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", and "a third" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise. All directional indications (such as up, down, left, right, front, back … …) in the embodiments of the present application are merely used to explain the relative positional relationship, movement, etc. between the components in a particular gesture (as shown in the drawings), and if the particular gesture changes, the directional indication changes accordingly. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

The present application is described in detail below with reference to the accompanying drawings and examples.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a first embodiment of a short-circuit protection circuit of the present application. In the present embodiment, the short-circuit protection circuit 10 includes: a power supply circuit 11, a control circuit 12, and an output circuit 13.

The short-circuit protection circuit 10 provided in the present application is specifically used in a functional circuit that needs to be short-circuited, for example, a non-isolated DC-DC (direct current to direct current) power supply circuit 11 or any other reasonable circuit with short-circuit risk, so that when a short circuit occurs, the corresponding short-circuit loss can be reduced as much as possible, and adverse effects on each device in the short-circuit protection circuit 10 and the functional circuit are avoided.

It is to be understood that the power supply circuit 11 may be specifically integrated with a power supply, or correspondingly connected to an external power supply, so as to obtain a stable power supply from the outside, and after the power supply is adaptively adjusted to be converted into the first power supply, the first power supply is provided to the control circuit 12.

The control circuit 12 is specifically connected to the power supply circuit 11, so as to receive a first power supply provided by the power supply circuit 11 correspondingly, and thus, a transmission mode of the control signal can be determined according to the first power supply.

The transmission method may specifically include the control circuit 12 transmitting a control signal to the output circuit 13, or not transmitting a control signal to the output circuit 13, or adjusting the control signal and then transmitting an adjusted control signal to the output circuit 13. And the control circuit 12 determines the particular manner in which the current control signal is sent in particular in response to whether the voltage of the first power supply exceeds a set voltage threshold.

Further, the output circuit 13 is correspondingly connected to the power supply circuit 11 and the control circuit 12, and is used for being connected to an external load circuit 101, so that when the output circuit 13 receives a control signal transmitted from the control circuit 12, the control signal can be transmitted to the load circuit 101.

When the load circuit 101 is shorted, and specifically, two terminals of the output circuit 13 and the load circuit 101 are shorted, or any reasonable loop in the load circuit 101 is shorted, so that when an abnormally large current occurs at two terminals of the output circuit 13 and the load circuit 101, the load circuit 101 will trigger the voltage of the first power supply to be periodically and gradually reduced to be lower than the set voltage threshold value through the output circuit 13, and then gradually increased to be higher than the set voltage threshold value, and the cycle is repeated until the short circuit of the load circuit 101 is relieved, and the short circuit protection circuit 10 resumes the normal working state.

It should be noted that the set voltage threshold is specifically understood as a start-up threshold voltage of the control circuit 12, so that when the voltage of the first power source provided to the control circuit 12 by the power source circuit 11 is lower than the set voltage threshold, the control circuit 12 will stop working, and not send the control signal to the output circuit 13, and when the first power source is restored to be higher than the set voltage threshold, restart sending the control signal to the output circuit 13.

In the above scheme, when the load circuit 101 is shorted, the short-circuit protection circuit 10 periodically gradually reduces the voltage of the first power supply to be lower than the set voltage threshold value and then gradually increases the voltage of the first power supply to be higher than the set voltage threshold value, so that the control circuit 12 intermittently sends a control signal to the load circuit 101, and then the short-circuit protection circuit 10 intermittently works, and the output circuit 13 intermittently provides output for the load, so that the short-circuit loss can be effectively reduced, and the configuration requirement and the working temperature of each device in the short-circuit protection circuit 10 are reduced, thereby avoiding adverse effects on the service life of each device.

It can be understood that the short-circuit protection circuit 10 and the load circuit 101 will not generate short-circuit loss in the interval time when the control circuit 12 does not output the control signal, that is, the short-circuit loss can be effectively reduced by increasing the interval time as much as possible by adjusting the circuit parameters, so that the damage risk caused by continuous temperature rise of each device in the short-circuit protection circuit 10 and the load circuit 101 during short-circuit can be avoided, the configuration requirement and the working temperature of each device in the short-circuit protection circuit 10 are reduced, and adverse effects on the service life of each device are avoided. After the short-circuit is released, the short-circuit protection circuit 10 can automatically and timely recover the normal power supply to the load circuit 101, so that the influence caused by the short-circuit is minimized. The short-circuit protection circuit 10 is simple and reliable, low in implementation cost and wide in application scene.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a second embodiment of the short-circuit protection circuit of the present application. The present embodiment is based on the first embodiment of the short-circuit protection circuit provided in the present application, and the power supply circuit 21 in the short-circuit protection circuit 20 specifically further includes a first resistor R1 and a first capacitor C1.

Specifically, a first end of the first resistor R1 is used for being connected to the external first power supply VCC, and a second end of the first resistor R1 is correspondingly connected to the output circuit 23, the control circuit 22 and the first end of the first capacitor C1, and a second end of the first capacitor C1 is connected to the control circuit 22.

When receiving the second power supplied by the first power supply VCC, the first resistor R1 can store or discharge the second power through the first resistor R1 and the first capacitor C1, so as to convert the second power into the first power, and supply the first power to the control circuit 22.

Alternatively, the second power source provided by the first power supply VCC may specifically be a dc power source with any reasonable voltage level and capable of outputting stably.

It should be noted that, the first capacitor C1 may be connected in parallel with the control circuit 22, and the corresponding first capacitor C1 has the same working voltage as the control circuit 22, so that when the load circuit (not shown) is shorted, the current flowing through the first resistor R1 will also become larger, so that the voltage drop across the first capacitor C1, that is, the voltage across the first capacitor C1 drops until the voltage drops below the starting threshold voltage of the control circuit 22, that is, the set voltage threshold, the control circuit 22 stops working, and the first capacitor C1 will be charged through the first resistor R1, so that when the voltage across the first capacitor C1 gradually rises to exceed the set voltage threshold, the control signal is started to be sent to the output circuit 23 again, but at this time, if the short circuit is not released, the above process will be repeated, so as to implement the repeated hiccup protection until the short circuit protection circuit 20 returns to normal after the short circuit is released.

Optionally, the resistance of the first resistor R1 may be specifically 10 Ω (ohm) -150 Ω, so as to ensure that the short-circuit protection circuit 20 has less loss during normal operation, and at the same time, the interval time between stopping operation of the control circuit 22 when the load circuit is shorted can be increased as much as possible, so as to reduce the short-circuit loss.

In one embodiment, the output circuit 23 includes a driving transformer T, and the driving transformer T further includes a primary winding Np and a secondary winding (not shown) magnetically connected to each other, wherein a first end of the primary winding Np is connected to the power circuit 21, a second end of the primary winding Np is connected to the control circuit 22, and the first end and the second end of the secondary winding are respectively connected to the first end and the second end of the load circuit, so that when the driving transformer T receives a control signal sent by the control circuit 22, the control signal can be converted, and the converted control signal is sent to the load circuit.

It can be understood that the power supply circuit 21 and the control circuit 22 are connected with each other through the driving transformer T

After the load circuit is electrically isolated, the power supply circuit 21 and the control circuit 225 can be effectively prevented from interfering with and damaging the operation and the operation of the load circuit.

Further, in an embodiment, the secondary winding specifically further includes a first secondary winding Ns1 and a second secondary winding Ns2, and the load circuit further includes a first sub-load circuit (not shown) and a second sub-load circuit (not shown), and the first secondary winding

The first and second terminals of the winding Ns1 are specifically for connecting the first 0 terminal OUT1+ and the second terminal OUT 1-of the first sub-load circuit, respectively, and the first and second terminals of the second sub-secondary winding Ns2 are for connecting the first terminal OUT + and the second terminal OUT-of the second sub-load circuit, respectively.

When receiving the control signal sent by the control circuit 22, the driving transformer T converts the control signal and sends the control signal to the first sub-load circuit.

In one embodiment, the output circuit 23 further includes a first diode D1, and the first terminal of the second sub-secondary 5-side winding Ns2 is connected to the first terminal of the first diode D1

The second terminal of the secondary winding Ns2 is connected to the second terminal OUT-of the second sub-load circuit, and the second terminal of the first diode D1 is connected to the first terminal out+ of the second sub-load circuit.

It will be appreciated that when the load circuit is shorted, and in particular, the first terminal out+ of the second sub-load circuit is shorted with the second terminal thereof, the voltage of the second sub-secondary winding Ns2 will be clamped at 0 the forward turn-on voltage of the first diode D1, which corresponds to the short circuit, so that the current flowing through the second sub-secondary winding Ns2 is increased, and thus the current flowing through the primary winding Np is increased.

In one embodiment, the output circuit 23 of the short-circuit protection circuit 20 further includes a second resistor R2, and the first end of the first secondary winding Ns1 is specifically connected to the second resistor R2

The first terminal, the second terminal of the first sub-secondary winding Ns1 is connected to the second terminal 5OUT 1-of the first sub-load circuit, and the second terminal of the second resistor R2 is connected to the first terminal OUT1+.

The first sub-load circuit may be specifically a buck-boost topology circuit, and when the control circuit 22 sends a control signal to the first sub-load circuit through the output circuit 23, the on-off state of a corresponding switching device in the buck-boost topology circuit can be adjusted by the control signal, so as to adjust the voltage conversion of the buck-boost topology circuit.

In an embodiment, the control circuit 22 in the short-circuit protection circuit 20 further includes a driving chip IC and a first switching tube Q1, the driving chip IC is specifically connected to the power supply circuit 21 and the first switching tube Q1, and the first switching tube Q1 connects the power supply circuit 21 and the output circuit 23.

When the driving chip IC receives the first power supplied from the power circuit 21, the driving chip IC determines a transmission mode of a control signal according to the first power, and when determining that the voltage of the first power is higher than a set voltage threshold, the driving chip IC transmits the control signal to the first switching tube Q1, so as to adjust the control signal through the first switching tube Q1, and then transmits the adjusted control signal to the output circuit 23.

It can be understood that the set voltage threshold value specifically corresponds to a start threshold 0 voltage of the driver chip IC, or a holding voltage, and the control signal specifically corresponds to a PWM (Pulse width modulation ) signal, so as to determine whether to send out the PWM signal by the voltage level based on the first power supply and the adopted current fed back to the control chip by the load circuit, and

or adjust the duty cycle of the PWM signal.

Optionally, the driving chip IC may be replaced by any reasonable circuit with a signal processing function, such as an MCU (micro controller5 Unit) circuit, which is not limited in this application.

It should be noted that the working principle of the short-circuit protection circuit 20 may specifically be:

after the first power supply VCC is supplied, the first power supply VCC is supplied through the first resistor R1 and

the first capacitor C1 supplies power to the driving chip IC, and when the 0 voltage of the first power supply supplied to the driving chip IC is higher than the start threshold voltage of the driving chip IC, the driving chip IC has a PWM signal output, that is, a control signal is externally sent.

Wherein the second sub-secondary winding Ns2 of the driving transformer T is connected in parallel to the first terminal OUT+ and the second terminal OUT-of the second sub-load circuit via a first diode D1, i.e. the first diode

The cathode of the tube D1 is correspondingly connected to the first terminal out+ of the second sub-load circuit, while the other end of the second sub-secondary 5 winding Ns2 is connected to the second terminal OUT-of the second sub-load circuit.

It will be appreciated that when the generated voltage of the second sub-secondary winding Ns2 is lower than the voltage between the first end out+ of the second sub-load circuit and the second end OUT-of the second sub-load circuit of the main power output, the other winding of the driving transformer T, i.e. the first sub-secondary winding Ns1, will pass

The second resistor R2 sends PWM signals to the first sub-load circuit so as to drive a switching tube inside the first sub-load circuit to act; when the second sub-load circuit is short-circuited, that is, the first end OUT+ of the second sub-load circuit is short-circuited with the second end OUT-, a wave-by-wave current limiting scheme is realized through a sampling resistor (not shown) in the second sub-load circuit, and the driving chip IC continuously sends OUT PWM signals; however, since the second sub-secondary winding Ns2 in the driving transformer T is correspondingly connected to the first terminal out+ of the second sub-load circuit and the second terminal OUT-of the second sub-load circuit through the first diode D1, when a short circuit occurs, the voltage across the second sub-secondary winding Ns2 is clamped to the forward conducting voltage Vf of the first diode D1, which corresponds to the short circuit, the current flowing through the primary winding Np increases, so that the voltage drop across the first resistor R1 increases, and the voltage across the first capacitor C1 decreases.

When the voltage across the first capacitor C1 is lower than the holding voltage of the driving chip IC, the driving chip IC will stop sending the PWM signal, and the first capacitor C1 will be charged again through the first resistor R1, so that when the voltage across the first capacitor C1 reaches the start threshold voltage of the driving chip IC, the driving chip IC will have the PWM signal output again, but at this time, the first terminal out+ of the second sub-load circuit and the second terminal OUT of the second sub-load circuit will repeat the above process if still maintained in the short circuit state, and further realize the repeated hiccup protection, until the short circuit is relieved, the short circuit protection circuit 20 resumes the normal operation.

Therefore, the short-circuit protection circuit 20 is simple and reliable, has low implementation cost, generates very low power loss after short-circuit protection, and can resume normal operation in time after the short-circuit is released.

The application further provides a power conversion circuit, please refer to fig. 3, fig. 3 is a schematic structural diagram of a first embodiment of the power conversion circuit. In the present embodiment, the power conversion circuit 30 includes: a buck-boost topology circuit 31 and a short-circuit protection circuit 32.

Specifically, the buck-boost topology circuit 31 is connected to the short-circuit protection circuit 32 and is used for connecting the external second power supply 102 and the load circuit 103, so that when the buck-boost topology circuit 31 receives the third power supply provided by the second power supply 102 and the control signal sent by the short-circuit protection circuit 32, the voltage of the third power supply can be converted according to the control signal, and the third power supply after the voltage conversion can be provided to the load circuit 103.

Alternatively, the third power source provided by the second power source 102 may specifically be a dc power source with any reasonable voltage level, which is not limited in this application.

The short-circuit protection circuit 32 may be specifically the short-circuit protection circuit 10 or the short-circuit protection circuit 20 as described in any of the above, and is specifically referred to in fig. 1-2 and related text, and will not be described herein.

Referring to fig. 4, fig. 4 is a schematic structural diagram of a second embodiment of the power conversion circuit of the present application. The present embodiment is based on the first embodiment of the power conversion circuit provided in the present application, and the buck-boost topology circuit 41 in the power conversion circuit 40 specifically further includes a second switching tube Q2, an inductor L, a second diode D2, a third resistor R3, and a second capacitor C2.

The first end of the second switching tube Q2 is connected to the first end dc+ of the second power supply, the second end of the second switching tube Q2 is connected to the first end of the short-circuit protection circuit 42, the third end of the second switching tube Q2 is connected to the second end of the short-circuit protection circuit 42, the first end of the inductor L and the second end of the second diode D2, the second end of the inductor L is connected to the third end of the short-circuit protection circuit 42, the first end of the second capacitor C2, the first end out+ of the load circuit, the second end of the third resistor R3 and the fourth end of the short-circuit protection circuit 42, the first end of the second diode D2 is connected to the second end OUT-, the first end of the second capacitor C2 and the fifth end of the short-circuit protection circuit 42, and the second end of the third resistor R3 is connected to the second end DC-of the second power supply.

It should be noted that, the short-circuit protection circuit 42 specifically further includes a first resistor R1, a first capacitor C1, a driving chip IC, a first switching tube Q1, a driving transformer T, a primary winding Np, a first secondary winding Ns1, a second secondary winding Ns2, a second resistor R2, and a first diode D1, and the corresponding relationship between the first end to the fifth end of the short-circuit protection circuit 42 and each element and the corresponding electrical connection manner are shown in fig. 4, which can be specifically combined with reference to fig. 2 and related text and will not be described herein.

It is understood that the buck-boost topology circuit 41 may be a non-isolated DC-DC power circuit, and the second power supply may be configured to provide the third power to the non-isolated DC-DC power circuit, and then convert the voltage of the third power supply by the non-isolated DC-DC power circuit, and output the converted voltage to the load circuit.

The short-circuit protection circuit 42 provides short-circuit protection for the buck-boost topology circuit 41 and the load circuit, and can adjust the on-off time duty ratio of the second switching tube Q2 by adjusting the duty ratio of the PWM signal, which is the control signal correspondingly output to the buck-boost topology circuit 41, so as to adjust the voltage conversion state of the buck-boost topology circuit 41, thereby realizing the buck-boost function.

Compared with the prior art, when the control circuit in the short-circuit protection circuit receives the first power supply provided by the power supply circuit, the transmission mode of the control signal can be determined according to the first power supply, the output circuit receives the control signal transmitted by the control circuit and transmits the control signal to the load circuit, so that when the load circuit is in short circuit, the voltage of the first power supply is gradually reduced to be lower than a set voltage threshold value and then gradually increased to be higher than the set voltage threshold value, when the voltage of the first power supply is lower than the set voltage threshold value, the control circuit does not transmit the control signal to the output circuit, and when the voltage of the first power supply is higher than the set voltage threshold value, the control circuit transmits the control signal to the output circuit, so that when the load circuit is in short circuit, the output provided to the load circuit can be repeatedly disconnected and then opened, the short-circuit protection circuit works intermittently, the configuration requirements and the working temperature of all devices in the short-circuit protection circuit and the load circuit are reduced, and adverse effects on the service life of all devices are avoided. After the short circuit is relieved, the short circuit protection circuit can automatically and timely recover normal power supply to the load circuit, and the influence caused by the short circuit is minimized.

The foregoing is only the embodiments of the present application, and not the patent scope of the present application is limited by the foregoing description, but all equivalent structures or equivalent processes using the contents of the present application and the accompanying drawings, or directly or indirectly applied to other related technical fields, which are included in the patent protection scope of the present application.

Claims

1. A short-circuit protection circuit, the short-circuit protection circuit comprising:

a power supply circuit;

the control circuit is connected with the power supply circuit to receive a first power supply provided by the power supply circuit and determine a transmission mode of a control signal according to the first power supply;

the output circuit is connected with the power supply circuit and the control circuit and is used for being connected with an external load circuit, receives a control signal sent by the control circuit and sends the control signal to the load circuit, so that when the load circuit is short-circuited, the voltage of the first power supply is gradually reduced to be lower than a set voltage threshold periodically and then is gradually increased to be higher than the set voltage threshold;

wherein the control circuit is to not send the control signal to the output circuit when the voltage of the first power supply is below the set voltage threshold, and to send the control signal to the output circuit when the voltage of the first power supply is above the set voltage threshold.

2. The short-circuit protection circuit according to claim 1, wherein,

the power supply circuit comprises a first resistor and a first capacitor, wherein a first end of the first resistor is used for being connected with an external first power supply, a second end of the first resistor is connected with the output circuit, the control circuit and the first end of the first capacitor, a second end of the first capacitor is connected with the control circuit, and the first resistor receives a second power supply provided by the first power supply so as to store or discharge the second power supply through the first resistor and the first capacitor, so that the second power supply is converted into the first power supply.

3. The short-circuit protection circuit of claim 2, wherein,

the resistance value of the first resistor is 10 omega-150 omega.

4. The short-circuit protection circuit according to claim 1, wherein,

the output circuit comprises a driving transformer, the driving transformer comprises a primary winding and a secondary winding which are mutually and magnetically connected, a first end of the primary winding is connected with the power supply circuit, a second end of the primary winding is connected with the control circuit, a first end and a second end of the secondary winding are respectively used for being connected with a first end and a second end of the load circuit, and the driving transformer receives the control signal sent by the control circuit and sends the control signal to the load circuit after conversion.

5. The short-circuit protection circuit according to claim 4, wherein,

the secondary winding comprises a first sub secondary winding and a second sub secondary winding, the load circuit comprises a first sub load circuit and a second sub load circuit, the first end and the second end of the first sub secondary winding are respectively used for connecting the first end and the second end of the first sub load circuit, the first end and the second end of the second sub secondary winding are respectively used for connecting the first end and the second end of the second sub load circuit, and the driving transformer receives the control signal sent by the control circuit, converts the control signal and sends the control signal to the first sub load circuit.

6. The short-circuit protection circuit according to claim 5, wherein,

the output circuit further comprises a first diode, a first end of the second sub-secondary winding is connected with the first end of the first diode, a second end of the second sub-secondary winding is connected with the second end of the second sub-load circuit, and the second end of the first diode is connected with the first end of the second sub-load circuit.

7. The short-circuit protection circuit according to claim 5, wherein,

8. The short-circuit protection circuit according to claim 1, wherein,

the control circuit further comprises a driving chip and a first switching tube, the driving chip is connected with the power supply circuit and the first switching tube, the first switching tube is connected with the power supply circuit and the output circuit, the driving chip receives the first power supply provided by the power supply circuit, determines a transmission mode of the control signal according to the first power supply, and transmits the control signal to the first switching tube when determining to transmit the control signal, so that the control signal is transmitted to the output circuit after being regulated by the first switching tube.

9. A power conversion circuit, the power conversion circuit comprising: the buck-boost topology circuit is connected with the short-circuit protection circuit and is used for connecting an external second power supply and a load circuit, receives a third power supply provided by the second power supply and a control signal sent by the short-circuit protection circuit, and performs voltage conversion on the third power supply according to the control signal so as to provide the third power supply after voltage conversion for the load circuit;

wherein the short-circuit protection circuit is a short-circuit protection circuit according to any one of claims 1-8.

10. The power conversion circuit of claim 9, wherein the power conversion circuit comprises a power converter,

the buck-boost topology circuit comprises a second switch tube, an inductor, a second diode, a third resistor and a second capacitor;

the first end of the second switch tube is connected with the first end of the second power supply, the second end of the second switch tube is connected with the first end of the short-circuit protection circuit, the third end of the second switch tube is connected with the second end of the short-circuit protection circuit, the first end of the inductor and the second end of the second diode, the second end of the inductor is connected with the third end of the short-circuit protection circuit, the first end of the third resistor, the first end of the load circuit, the second end of the second capacitor and the fourth end of the short-circuit protection circuit, the first end of the second diode is connected with the second end of the load circuit, the first end of the second capacitor and the fifth end of the short-circuit protection circuit, and the second end of the third resistor is connected with the second end of the second power supply.