CN112787311A

CN112787311A - Protection circuit for power supply and power supply

Info

Publication number: CN112787311A
Application number: CN201911095576.XA
Authority: CN
Inventors: 王建航; 梁新春
Original assignee: ZTE Corp
Current assignee: Shenzhen Zte Technical Service Co ltd
Priority date: 2019-11-11
Filing date: 2019-11-11
Publication date: 2021-05-11
Also published as: WO2021093711A1

Abstract

The application relates to a protection circuit for a power supply and the power supply. The protection circuit includes: the detection module comprises a detection input end and a detection output end, wherein the detection input end is used for acquiring a fault signal of the power supply; and the response module comprises at least one first switching device for controlling the slow-start switching tube to be switched off, and the control end of the first switching device is connected to the detection output end. The embodiment of the application adopts a detection module to detect the fault signal of the power supply; and receiving the fault signal by using a response module, and outputting an action signal according to the fault signal so as to control the slow-start switching tube of the power supply to be switched off. The quick turn-off of the slow-start switch tube is realized when a fault occurs, and the stress requirement on the slow-start switch tube is effectively reduced.

Description

Protection circuit for power supply and power supply

Technical Field

The embodiment of the application relates to but is not limited to the technical field of power supplies, and particularly relates to a protection circuit for a power supply.

Background

In power circuit design, in order to limit inrush current, a slow start circuit, which may also be referred to as a soft start circuit, is usually designed in an input loop. The slow start circuit is commonly implemented in four ways: firstly, the resistor is started slowly, secondly, the MOS (Metal Oxide Semiconductor) tube is started slowly, thirdly, the resistor and the relay are started slowly, and fourthly, the resistor and the switch tube (such as the MOS tube) are started slowly.

In the existing slow start circuit structure using a resistor and a switching tube as slow start, whether an input loop can be quickly turned off and whether the parallel switching tube is damaged by a large current which quickly rises or not is the key for ensuring whether protection can be realized under the condition that a short circuit occurs between power buses. Otherwise, the power supply may be smoked and ignited due to long-time large current, and safety accidents are caused. In particular, the higher the power, the more switching tubes connected in parallel, the more serious the situation. Normally, a switching tube (such as a MOS tube) to be turned off and on needs to reduce its driving voltage (such as a gate-source voltage Vgs) below its turn-on threshold. Thus, the timing of when to select to turn off and the time required to turn off when a fault occurs determines the timeliness of protection and stress requirements on the switching device.

At present, the conventional method is as follows: on one hand, the singlechip is used for operating control software, and when a fault is detected, an instruction is output to close the driving voltage of the switching tube; on the other hand, a switching tube having high impact resistance is selected. On one hand, however, the singlechip is used for operating the control software, and a switching instruction is given after the software is judged by the detected signal, and the time is long from the time when the switching tube is switched on and off; once a short circuit occurs between the power buses, the current will rapidly rise in a short time, which may cause the power to smoke and fire, resulting in safety accidents. On the other hand, when a fault occurs, the current rapidly rises in a short time, and even if a switch tube with large size and strong impact resistance is selected, the potential safety hazard of smoke and fire generation in the case of abnormal short circuit of a power bus cannot be fundamentally eliminated.

Disclosure of Invention

The embodiment of the application provides a protection circuit and a power for power, can realize that turn-off slowly opens the switch tube when the trouble takes place fast to effectively reduce the stress requirement to slowly opening the switch tube.

In a first aspect, an embodiment of the present application provides a protection circuit for a power supply, the power supply includes a power bus and a slow-start switch tube, and is characterized in that the protection circuit includes:

the detection module comprises a detection input end and a detection output end, and the detection input end is electrically connected with the power supply bus;

and the response module comprises at least one first switching device for controlling the slow-start switching tube to be switched off, and the control end of the first switching device is connected to the detection output end.

In a second aspect, an embodiment of the present application provides a power supply, including:

a power supply input terminal;

the power supply bus is connected with the power supply input end;

a power supply output terminal;

the slow starting circuit is arranged at the power bus and used for slowly starting the power supply; the slow starting circuit comprises a slow starting resistor and a slow starting switching tube which are connected in parallel;

a protection circuit for a power supply as described in the first aspect.

The embodiment of the application comprises the following steps: detecting a fault signal of a power supply by using a detection module; and receiving the fault signal by using a response module, and outputting an action signal according to the fault signal so as to control the slow-start switching tube of the power supply to be switched off. The quick turn-off of the slow-start switch tube is realized when a fault occurs, and the stress requirement on the slow-start switch tube is effectively reduced.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the claimed subject matter and are incorporated in and constitute a part of this specification, illustrate embodiments of the subject matter and together with the description serve to explain the principles of the subject matter and not to limit the subject matter.

FIGS. 1a, 1b, 1c, and 1d are schematic diagrams of four common slow start circuits respectively;

FIG. 2 is a schematic diagram of a position and an implementation manner of a soft start circuit in a switching power supply in the related art;

FIG. 3 is a schematic diagram of a position and an implementation manner of a slow start circuit structure for a slow start by a resistor and an MOS transistor in a switching power supply according to the related art;

fig. 4 is a schematic structural diagram of a protection circuit according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of a position of a protection circuit in a power supply according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of a protection circuit according to another embodiment of the present application;

fig. 7 is a schematic structural diagram of a protection circuit according to another embodiment of the present application;

fig. 8 is a schematic structural diagram of a position of a protection circuit in a power supply according to another embodiment of the present application;

fig. 9 is a schematic structural diagram of a protection circuit according to another embodiment of the present application;

FIG. 10 is a schematic diagram of a power supply according to an embodiment of the present application;

FIG. 11 is a schematic diagram of a power supply according to another embodiment of the present application;

FIG. 12 is a graph showing comparison between the effects before and after the embodiment of the present invention is carried out.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. In the present application, the embodiments and features of the embodiments may be arbitrarily combined with each other without conflict.

It should be noted that although functional blocks are partitioned in a schematic diagram of an apparatus and a logical order is shown in a flowchart, in some cases, the steps shown or described may be performed in a different order than the partitioning of blocks in the apparatus or the order in the flowchart. The terms first, second and the like in the description and in the claims, and the drawings described above, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

In power circuit design, in order to limit inrush current, a slow start circuit, which may also be referred to as a soft start circuit, is usually designed in an input loop. The slow start circuit is commonly implemented in four ways: firstly, the resistor is started slowly (refer to fig. 1a), secondly, the MOS transistor is started slowly (refer to fig. 1b), thirdly, the resistor and the relay are started slowly (refer to fig. 1c), and fourthly, the resistor and the switching transistor (such as the MOS transistor) are started slowly (refer to fig. 1 d). For example, fig. 2 illustrates the location and implementation of a soft start circuit in a switching power supply; fig. 3 illustrates the position and implementation manner of a slow start circuit structure for a resistor plus a MOS transistor as slow start in a switching power supply in the related art.

For example, a slow start circuit structure of a related art switching power supply is shown in fig. 3. The circuit structure is usually used in a switching power supply with larger power, the slow start circuit comprises a plurality of slow start MOS tubes Q1 and a slow start resistor R1, the plurality of slow start MOS tubes Q1 are connected with the slow start resistor R1 in parallel, and the on-off state of each slow start MOS tube Q1 is controlled by a slow start MOS drive unit (a slow start switch drive circuit). The scheme can meet the requirement on the limitation of surge current and is helpful for improving the efficiency of the power supply. The slow start circuit structure is characterized in that a slow start resistor R1 is used for limiting surge current in the power-on process, and when the voltage of an input bus capacitor on a power bus reaches a certain value, a slow start MOS driving unit outputs a driving instruction to control the conduction of a slow start MOS tube Q1; when a fault (such as a power bus short circuit) occurs, the soft-start MOS driving unit outputs a driving instruction to close the soft-start MOS transistor Q1. The slow-start MOS driving unit generally detects an electrical signal of a power bus or a temperature signal of a slow-start circuit by using a single chip or discrete components to determine a power failure state. The software judgment of the singlechip is detected from the electric signal of the power bus or the temperature signal of the slow start circuit, and the time of dozens of milliseconds is usually needed to give a driving instruction and then to finish the switching action of the slow start MOS tube Q1; once a short circuit occurs between power buses in normal operation, current rises to hundreds of amperes within a short time of tens of nanoseconds to hundreds of nanoseconds, a single chip cannot complete protection under such a rapid condition, a large current of hundreds of even thousands of amperes easily damages the slow-start MOS tube Q1 to cause short circuit and cannot break an input loop, and then the continuous large current can cause the temperature rise of the power supply to rise rapidly, so that even if the slow-start MOS tube Q1 with large size and strong impact resistance is selected, the potential safety hazard of smoke and fire generation during abnormal short circuit in the power supply cannot be fundamentally solved.

Based on this, this application embodiment provides a protection circuit and power for power. Specifically, to the problem that the slow-start switch tube was turned off untimely and probably caused great potential safety hazard when short-circuit fault took place, this application embodiment has increased protection circuit on the basis of the normal switch of slow-start switch tube, can realize just beginning to trigger the turn-off action to the slow-start switch tube when the trouble takes place, can realize that the fast turn-off slowly turns off the slow-start switch tube when the trouble takes place to effectively reduce the stress requirement to the slow-start switch tube.

It should be noted that in the following embodiments, the power supply may be a switching power supply, or may be other types of power supplies (such as a linear power supply); the power supply can be a direct current power supply or an alternating current power supply. The following description will be given only by taking a dc switching power supply as an example. The slow starting circuit adopts a slow starting resistor and a slow starting switch tube to perform slow starting. The slow starting resistor can adopt various types of resistors, such as a constant resistor, a thermistor and the like; the slow-start switch tube can adopt various switch tubes, such as a triode, an MOS tube and the like. The number of the slow starting resistor and the slow starting switch tube can be set randomly according to actual conditions. The following description will be given only by taking an example in which the soft-start switch is a MOS transistor and the soft-start resistor is a positive temperature coefficient thermistor. The slow starting resistor and the slow starting switch tube can be arranged on a positive line (a positive input line) of a power bus, can also be arranged on a negative line (a negative input line) of the power bus, and can also be arranged on the positive line and the negative line of the power bus simultaneously (the positive line is provided with the slow starting resistor and the slow starting switch tube, and the negative line is also provided with the slow starting resistor and the slow starting switch tube). The following description will be made only by taking an example in which the slow start resistor and the slow start switching tube are provided on the negative line of the power bus. The fault signal may be an electrical fault signal or an over-temperature signal, etc. For example, the detection module may obtain an electrical fault signal by detecting an electrical signal of the power bus; the over-temperature signal can also be obtained by detecting the temperature signal of the slow-start switch circuit by using a temperature sensor. The following description will be given only by taking an example of obtaining an electrical fault signal by detecting an electrical signal of a power bus.

In a first aspect, an embodiment of the present application provides a protection circuit for a power supply. The protection circuit can be an independent circuit module or a circuit submodule integrated in the power supply circuit.

Example 1A

Referring to fig. 4, the protection circuit for a power supply of the present example includes:

In some examples, the power supply includes a power bus bar and a soft start switch tube. The detection module can be used for detecting the electric signal of the power bus. The electrical signal may be a voltage signal or a current signal, and the present embodiment is described by taking the electrical signal as the voltage signal.

In some examples, referring to fig. 5, the detection module of the protection circuit is connected to the common ground (i.e. the protection circuit is referenced to the ground) of the slow-start switch driving circuits (e.g. the slow-start MOS driving units) of the slow-start switch transistors Q1 to Qn, and the output terminal of the first switching device in the response module may be connected to the control terminals of the slow-start switch transistors Q1 to Qn to directly drive the slow-start switch transistors Q1 to Qn, so as to control the slow-start switch transistors Q1 to Qn to turn off in case of a fault.

The following is an application example.

Application example 1A-1

Referring to fig. 6, in this application example, the detection module includes a first voltage-dividing resistor R6 and a second voltage-dividing resistor R7 for voltage signal sampling, after the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 are connected in series, one end of the first voltage-dividing resistor R6 is connected to the positive line of the power bus as the detection input terminal, one end of the second voltage-dividing resistor R7 is connected to the negative line of the power bus as the protection circuit reference ground, and the protection circuit reference is located at the left end point of the slow start resistor R1 (i.e., the network located before the slow start circuit), and the connection node of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 is connected to the input terminal of the response module as the detection output terminal of the detection module.

In this application example, the detection output end of the detection module of the response module is connected with the input end of the response module; the response module comprises at least one first switching device VT1, wherein the first switching device VT1 is used for receiving the electric signal and outputting an action signal according to the electric signal so as to control the slow-start switching tubes Q1 to Q4 of the power supply to be turned off. The first switching device VT1 is a device (non-software control device) that uses hardware to implement the determination and the switching action, such as a triode, a MOS transistor, or other devices with a switching function. The number of the first switching devices VT1 may be one, or may be multiple, for example, a plurality of first switching tubes may be driven in cascade. In this example, the first switching device VT1 employs a PMOS transistor, and the gate of the PMOS transistor is connected to the detection output terminal (the connection node of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7) of the detection module as the control terminal of the response module. In some examples, the response module further includes a first protection diode D1 and a second protection diode D2. The anode of the first protection diode D1 is connected with the grid of the PMOS tube, and the cathode is connected with the source of the PMOS tube; the anode of the second protection diode D2 is connected to the base of the PMOS transistor, and the cathode is connected to the detection output terminal (the connection node of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7) of the detection module, that is, the base of the PMOS transistor is connected to the detection output terminal of the detection module through the second protection diode D2; the drain of the PMOS tube is connected with the negative line of the power bus as the reference ground of the protection circuit, and the reference of the protection circuit is positioned at the left end point of the slow starting resistor R1 (namely, a network positioned in front of the slow starting circuit). The source electrode of the PMOS tube is used for outputting an action signal to the control ends of the slow-start switch tubes Q1 to Q4 of the power supply so as to control the slow-start switch tubes Q1 to Q4 of the power supply to be turned off.

In this application example, when the power supply normally works, the voltage value obtained by dividing the voltage signal of the power supply bus through the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 is a high level, at this time, the voltage difference Vgs between the gate of the PMOS transistor and the source of the PMOS transistor is higher than the turn-on threshold voltage, so that the PMOS transistor VT1 is turned off, the action signal output by the PMOS transistor VT1 is a high level, and the slow-start switching transistors Q1 to Q4 maintain the turn-on state, so that the power supply normally works. After the slow start, when the power bus fails (for example, a short circuit occurs between a positive line and a negative line of the power bus), a voltage value obtained by voltage division of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 is rapidly reduced to a low level, at the moment, a voltage difference Vgs between a gate of the PMOS transistor and a source of the PMOS transistor is lower than a conduction threshold voltage, the PMOS transistor VT1 is rapidly turned on, and voltages of control ends of the slow start switching transistors Q1 to Q4 are pulled to the low level, so that the slow start switching transistors Q1 to Q4 can be turned off in a short time. The high current at fault will cause the ptc thermistor R1 to rise rapidly, causing the current in the loop to drop rapidly, and the power supply will then enter a hiccup protection mode with the characteristics of the thermistor.

Because the switch tube is turned off quickly when the switch tube is started slowly, the peak current of the input loop of the power bus is limited, the time of large current action is extremely short, the generated heat is reduced, and the risk of smoke and fire caused by power damage is effectively controlled. And because the time of heavy current effect is extremely short, the electric stress and the thermal stress requirement of circuit devices are greatly reduced, so that the specification requirement of the circuit on the slow-start switching tube Q1 is reduced, more economic devices can be selected, the cost is reduced, and the power performance is improved.

In some embodiments, as in embodiment 1A above, the response module may directly output a control command to turn off the soft-start switch. In other embodiments, such as embodiment 1B described below, the first switching device, in turn, controls the turn-off of the soft-start switch tube of the power supply through the isolation module and the secondary response module.

Example 1B

Referring to fig. 7, the protection circuit of the present example includes:

the detection module is used for detecting an electric signal of the power bus; the detection module comprises a detection input end and a detection output end, and the detection input end is electrically connected with the power supply bus;

the response module comprises at least one first switching device, and the control end of the first switching device is connected to the detection output end; the first switch device is used for receiving the electric signal and outputting an action signal according to the electric signal;

the isolation module is connected between the response module and the secondary response module and used for realizing signal isolation;

and the input end of the secondary response module is connected with the output end of the response module, and the secondary response module is used for controlling the turn-off of a slow-start switch tube Q1 of the power supply according to the action signal.

Referring to fig. 8, in some examples, since there is a difference between the reference ground of the detection signal and the reference ground of the driving signals of the slow-start switching transistors Q1 to Qn, that is, when the detection module of the protection circuit is not common to the slow-start switching driving circuits of the slow-start switching transistors Q1 to Qn, an isolation process is required, the isolation module may be used to achieve signal isolation between the response module and the secondary response module. The isolation module can be realized by electronic devices with an isolation function, such as an optical coupler U1 and an isolation chip U1. The response module controls the slow-start switch tube of the power supply to be turned off sequentially through the isolation module and the secondary response module.

The relevant description of the detection module can refer to the corresponding description of embodiment 1A, and is not repeated herein.

The response module comprises at least one first switching device VT1, wherein the first switching device VT1 is used for receiving the electric signal and outputting an action signal according to the electric signal so as to control the slow-start switch tube Q1 of the power supply to be turned off. The first switching device VT1 is a device (non-software control device) that uses hardware to implement the determination and the switching action, such as a triode, a MOS transistor, or other devices with a switching function. The number of the first switching devices VT1 may be one, or may be multiple, for example, a plurality of first switching tubes may be driven in cascade.

The secondary response module comprises at least one second switching device VT 2. The second switching device VT2 is a device (non-software controlled device) that uses hardware to implement the determination and the switching action, such as a triode, a MOS transistor, or other devices with a switching function. The number of the second switching devices VT2 may be one, or may be multiple, for example, a plurality of second switching tubes may be driven in cascade.

The following is illustrated with two application examples.

Application example 1B-1

Referring to fig. 9, the protection circuit of the present application example can be applied to a low-voltage dc power supply with high power (e.g., 2500W). The slow starting circuit adopts a positive temperature coefficient thermistor (slow starting resistor R1) and 6 slow starting MOS tubes (slow starting switch tubes) which are connected in parallel, the 6 MOS tubes are respectively a first slow starting MOS tube Q1 to a sixth slow starting MOS tube Q6, and the 6 MOS tubes are NMOS tubes. In some examples, to quickly turn off the drive of the slow-start MOS transistor, it is generally required to draw the gate-source charge of the slow-start MOS transistor with the capability of several amperes and maintain the low level for a period of time.

In this application example, the detection module includes a first voltage-dividing resistor R6 and a second voltage-dividing resistor R7 for sampling the voltage signal, after the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 are connected in series, one end of the first voltage-dividing resistor R6 is connected to the positive line of the power bus, one end of the second voltage-dividing resistor R7 is connected to the negative line of the power bus, and the connection node of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 is connected to the input end of the response module as the output end of the detection module.

The isolation module is realized by adopting an optical coupler U1. The optical coupler U1 includes a first input, a second input, a first output, and a second output.

The response module comprises a PNP transistor, and an emitter of the PNP transistor is connected to the second input terminal of the optocoupler U1. A first input terminal of the optocoupler U1 is connected to the first power supply terminal VCC1 through a fifth resistor R5. The collector of the PNP transistor is connected to the reference ground of the detection signal (i.e. the right end of the slow-start resistor R1, hereinafter referred to as the primary reference ground of the protection circuit), and the base is connected to the output terminal of the detection module (the connection node of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7). In some examples, the response module further includes a first protection diode D1 and a second protection diode D2. The anode of the first protection diode D1 is connected with the base electrode of the PNP triode, and the cathode of the first protection diode D1 is connected with the emitting electrode of the PNP triode; the anode of the second protection diode D2 is connected with the base of the PNP triode, and the cathode is connected with the output end of the detection module, that is, the base of the PNP triode is connected with the output end of the detection module through the second protection diode D2; the collector of the PNP triode is connected with the negative line of the power bus as the primary reference ground of the protection circuit, and the primary reference of the protection circuit is positioned at the right end point of the slow start resistor R1 (namely, the network positioned behind the slow start circuit). And the emitter of the PNP triode is used for outputting an action signal, and the action signal is transmitted to the secondary response module through the isolation module.

The secondary response module adopts a second MOS tube as a second switch tube. The second MOS transistor can select a small-signal MOS transistor (in this application example, a small-signal NMOS transistor is selected), so as to reduce the cost. The secondary response module further comprises a second power supply terminal VCC2, a third resistor R3, a fourth resistor R4 and a second capacitor C2. The second power supply terminal VCC2 is connected to the first output terminal of the optocoupler U1 through a fourth resistor R4, and the second output terminal of the optocoupler U1 is connected with the gate of the second MOS transistor. The gates of the second MOS transistors are respectively connected to the driving signal reference ground of the soft-start switch transistor Q1 (i.e. the left end point of the soft-start resistor R1) through a parallel circuit formed by a third resistor R3 and a second capacitor C2. The source of the second MOS transistor is connected to the driving signal reference ground of the soft-start switch transistor Q1, and the drain of the second MOS transistor is connected to the gates of the soft-start MOS transistors Q1 to Q6.

In this example, when the power supply normally operates, the voltage value obtained by dividing the voltage signal of the power bus through the first voltage dividing resistor R6 and the second voltage dividing resistor R7 is at a high level (for example, higher than the voltage of the first power supply terminal VCC 1), so that the PNP transistor VT1 is turned off, and the operation signal output by the PNP transistor VT1 is at a high level. The optocoupler U1 does not work, the second MOS transistor VT2 is in a cut-off working state, the MOS transistors Q1 to Q6 are started slowly to maintain a conducting state, and the power supply works normally. And after slowly starting, when the power bus breaks down (for example, short circuit appears between the positive line and the negative line of power bus), the voltage value that first divider resistance R6 and second divider resistance R7 partial pressure obtained falls to the low level fast (if be less than first supply terminal VCC1 voltage), PNP triode VT1 switches on fast, then opto-coupler U1 switches on, second MOS pipe VT2 also switches on fast, thereby can pull the voltage of the control end of parallelly connected 6 slowly-starting MOS pipes Q1 to Q6 to the low level in 1 ~ 2 microseconds, and then make 6 slowly-starting MOS pipes Q1 to Q6 turn off. The high current at fault will cause the ptc thermistor R1 to rise rapidly and the current in the loop to drop rapidly, and the power supply will then enter a hiccup protection mode with the characteristics of the thermistor.

Application example 1B-2

Referring to fig. 10, the protection circuit of the present application example can be applied to a low-voltage dc power supply of medium to high power (e.g., 1500W). The slow starting circuit adopts a positive temperature coefficient thermistor (slow starting resistor R1) and 4 slow starting MOS tubes (slow starting switch tubes) which are connected in parallel, wherein the 4 MOS tubes are respectively a first slow starting MOS tube Q1 to a fourth slow starting MOS tube Q4, and the 4 MOS tubes are NMOS tubes. In some examples, to quickly turn off the drive of the slow-start MOS transistor, it is generally required to draw the gate-source charge of the slow-start MOS transistor with the capability of several amperes and maintain the low level for a period of time.

Compared with the application example 1B-1, the application example is applied to a low-voltage direct-current power supply with smaller power, and therefore, the number of the soft start MOS transistors connected in parallel is reduced. The first switching device VT1 uses PMOS tube, the isolation module uses isolation chip U1, the second switching device VT2 uses NPN triode. The parameters of the peripheral third resistor R3 and the second capacitor C2 can be adjusted according to the actual situation. The rest of the circuit structure of application example 1B-2 is similar to that of application example 1B-1, and is detailed in fig. 9, which is not described herein again. The protection circuit of the application example 1B-2 can also be used for quickly switching off the slow-start MOS tube when a power bus fails, so that the purpose of protecting the power supply is achieved.

Referring to FIG. 12, the input loop current I is shown before and after the power supply adopts the embodiment of the present invention, at fault_inSize and duration of action. Before a protection circuit is added (the protection circuit is not adopted), a soft-start MOS driving unit is used for detecting when a fault occurs and software is used for shutting off a soft-start MOS tube, the peak current of an input loop current curve L1 reaches 800A, and the loop current curve L1 reaches 800AThe peak value of the current of the circuit is high, the acting time T1 of the current is long, and the power supply is easy to damage; after a protection circuit is added (the protection circuit is adopted), after an electric signal of a power bus behind a slow start position is detected in a hardware mode, the embodiment of the invention directly drives and closes the slow start MOS tube, the peak current of an input loop current curve L2 is about 300A, the peak value of the loop current is obviously reduced, the current action time T2 is shortened, and the reliability of the power supply is improved. Therefore, by adopting the embodiment of the invention, the quick turn-off of the slow-start switch tube Q1 can be realized when a fault occurs, and the stress requirement on the slow-start switch tube Q1 is effectively reduced.

In a second aspect, embodiments of the present application provide a power supply including the protection circuit according to the first aspect. The power supply can be a switch power supply, and can also be other types of power supplies (such as a linear power supply); the power supply can be a direct current power supply or an alternating current power supply. The following description will be given by taking only a dc power supply as an example.

Example 2

Referring to fig. 5 or 8 or 11, the power supply of the present example includes:

a power supply input terminal;

the power supply bus is connected with the power supply input end;

a power supply output terminal;

a protection circuit for a power supply as in embodiment 1A or embodiment 1B.

In some examples, the power supply input is for accessing an external power supply; the power supply bus comprises a positive line and a negative line, an input bus capacitor C1 is arranged between the positive line and the negative line, and the detection module of the protection circuit can monitor the working state of the power supply by detecting voltage signals (electrical signals) at two ends of the input bus capacitor C1. Obviously, the electrical signal may also be a current signal, a power signal, an impedance, etc.

In some examples, the power supply is a switching power supply, and the switching power supply further comprises a power conversion module connected between the power supply input terminal and the power supply output terminal. The power conversion module can be implemented by using a conventional power conversion circuit, and generally includes a circuit for converting a dc voltage into a pulse voltage, or a circuit for converting a dc voltage into a pulse voltage and then into a dc output voltage.

In some examples, the soft start circuit includes a soft start MOS driving unit, a soft start resistor R1, and a soft start switch Q1. The slow-start MOS driving unit can detect the working state of the power supply by detecting a voltage signal of a power supply bus, and outputs a control instruction to drive the slow-start switch tube Q1 so as to control the switching state of the slow-start switch tube Q1. The slow-start MOS driving unit can be realized by utilizing processors such as a singlechip and the like through a software processing mode, and can also be realized by utilizing a pure hardware mode formed by discrete devices. The slow starting resistor R1 and the slow starting switch tube Q1 can be arranged on a positive line (a positive input line) of a power bus, can also be arranged on a negative line (a negative input line) of the power bus, and can also be arranged on the positive line and the negative line of the power bus simultaneously (the positive line is provided with the slow starting resistor R1 and the slow starting switch tube Q1, and the negative line is also provided with the slow starting resistor R1 and the slow starting switch tube Q1). Fig. 5, 8, and 11 show a power circuit configuration in which the slow-start resistor R1 and the slow-start switching tube Q1 are provided on the negative line of the power bus. Fig. 5 illustrates a power circuit structure in which a detection module of a protection circuit is commonly grounded with a soft-start switch driving circuit of a soft-start switch tube (i.e., the detection module of the protection circuit is consistent with the reference ground of the soft-start switch driving circuit) before the protection circuit is disposed in the soft-start circuit; fig. 8 or fig. 11 illustrates a power circuit structure in which the detection module of the protection circuit is not grounded with the soft start switch driving circuit of the soft start switch tube after the protection circuit is disposed in the soft start circuit. The slow starting resistor R1 can adopt various types of resistors, such as a constant resistor, a thermistor and the like; the slow-start switch tube Q1 can adopt various types of switch tubes, such as a triode, a MOS tube, and the like. The number of the slow starting resistor R1 and the number of the slow starting switch tubes Q1 can be set arbitrarily according to actual conditions. Fig. 11 illustrates a circuit structure of the slow start circuit including a slow start resistor R1 and a slow start switch Q1, the slow start resistor R1 and the slow start switch Q1 are connected in parallel, and the circuit structure is generally suitable for a power supply with smaller power; fig. 8 illustrates a circuit structure of the slow start circuit including a slow start resistor R1 and a plurality of slow start switch transistors Q1 to Qn, wherein the slow start resistor R1 is connected in parallel with the plurality of slow start switch transistors Q1, and the circuit structure is generally suitable for power supplies with larger power.

By adopting the power supply of the embodiment, the aim of switching off the switch tube Q1 in microsecond level when a fault (such as short circuit) occurs can be fulfilled, so that the current size and action time in an input loop after the fault occurs are limited, and the risk of damage, smoke and fire of the power supply is effectively controlled. In addition, the requirements on the electric stress and the thermal stress of the slow-starting switch tube Q1 can be effectively reduced, so that the power supply can select the more economic slow-starting switch tube Q1, the cost is reduced, and the performance of the power supply is improved.

Referring to FIG. 12, the input loop current I is shown before and after the power supply adopts the embodiment of the present invention, at fault_inSize and duration of action. Before a protection circuit is added (the protection circuit is not adopted), a soft-start MOS driving unit is used for detecting and utilizing software to turn off a soft-start MOS tube when a fault occurs, the peak current of an input loop current curve L1 reaches 800A, the peak value of the loop current is high, the current action time T1 is long, and a power supply is easy to damage; after a protection circuit is added (the protection circuit is adopted), after an electric signal of a power bus behind a slow start position is detected in a hardware mode, the embodiment of the invention directly drives and closes the slow start MOS tube, the peak current of an input loop current curve L2 is about 300A, the peak value of the loop current is obviously reduced, the current action time T2 is shortened, and the reliability of the power supply is improved. Therefore, by adopting the embodiment of the invention, the quick turn-off of the slow-start switch tube Q1 can be realized when a fault occurs, and the stress requirement on the slow-start switch tube Q1 is effectively reduced.

The above-described embodiments of the apparatus are merely illustrative, wherein the units illustrated as separate components may or may not be physically separate, i.e. may be located in one place, or may also be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

One of ordinary skill in the art will appreciate that all or some of the steps, systems, and methods disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.

While the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and such equivalent modifications or substitutions are included in the scope of the present invention defined by the claims.

Claims

1. A protection circuit for a power supply, the power supply including a soft-start switch tube, the protection circuit comprising:

the detection module comprises a detection input end and a detection output end, wherein the detection input end is used for acquiring a fault signal of the power supply;

2. The circuit of claim 1, wherein the fault signal is an electrical fault signal or an over-temperature signal.

3. The circuit of claim 1, wherein the output terminal of the first switching device is connected to the control terminal of the slow-start switch tube.

4. The circuit of claim 1, further comprising an isolation module and a secondary response module, wherein the first switching device controls a slow-start switching tube of the power supply to be turned off sequentially through the isolation module and the secondary response module.

5. The circuit of claim 4, wherein the secondary response module comprises at least one second switching device, a control terminal of the second switching device is connected to the output terminal of the isolation module, an input terminal of the isolation module is connected to the output terminal of the first switching device, and an output terminal of the second switching device is used for controlling the soft-start switch to be turned off.

6. The circuit of any one of claims 1 to 5, wherein the first switching device is a triode or a MOS transistor.

7. A power supply, comprising:

a power supply input terminal;

the power supply bus is connected with the power supply input end;

a power supply output terminal;

a protection circuit for a power supply as claimed in any one of claims 1 to 6.

8. The power supply of claim 7, wherein the power supply is a switching power supply, the switching power supply further comprising a power conversion module coupled between the power supply input and the power supply output.

9. The power supply of claim 7 or 8, further comprising an input bus capacitor connected between the power buses, wherein the detection input is configured to obtain an electrical signal from the input bus capacitor.

10. The power supply of claim 7 or 8, wherein the slow start circuit comprises:

the circuit comprises a slow starting resistor and a slow starting switch tube, wherein the slow starting resistor and the slow starting switch tube are connected in parallel; or,

the circuit comprises a slow starting resistor and a plurality of slow starting switching tubes, wherein the slow starting resistor is connected with the plurality of slow starting switching tubes in parallel; or,

the circuit comprises a plurality of slow starting resistors and a slow starting switching tube, wherein the plurality of slow starting resistors and the slow starting switching tube are connected in parallel; or,

the circuit comprises a plurality of slow starting resistors and a plurality of slow starting switching tubes, wherein the plurality of slow starting resistors and the plurality of slow starting switching tubes are connected in parallel.