WO2021093711A1

WO2021093711A1 - Protection circuit for power supply, and power supply

Info

Publication number: WO2021093711A1
Application number: PCT/CN2020/127602
Authority: WO
Inventors: 王建航; 梁新春
Original assignee: 中兴通讯股份有限公司
Priority date: 2019-11-11
Filing date: 2020-11-09
Publication date: 2021-05-20
Also published as: CN112787311A

Abstract

A protection circuit for a power supply, and a power supply. The protection circuit comprises: a detection module comprising 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 a response module comprising at least one first switching device configured to control a soft-start switching tube to be switched off, wherein a control end of the first switching device is connected to the detection output end. The detection module is used to detect the fault signal of the power supply; and the response module is used to receive the fault signal, and to output an action signal according to the fault signal in order to control the soft start switching tube of the power supply to be switched off. The soft-start switching tube is thus quickly switched off when a fault occurs, and a stress requirement for the soft-start switching tube is effectively reduced.

Description

A protection circuit for power supply and power supply

Technical field

The embodiments of the present application relate to, but are not limited to, the technical field of power supplies, and in particular to a protection circuit for power supplies.

Background technique

In the power circuit design, in order to limit the impact current, a slow-start circuit is usually designed in the input loop, which can also be called a soft-start circuit. There are four commonly used implementation forms of slow-start circuits: one is resistance for slow start, the other is MOS (Metal Oxide Semiconductor) tube for slow start, the third is resistance and relay for slow start, and the fourth is resistance. Add a switch tube (such as MOS tube) for slow start.

In the slow-start circuit structure in the related art where the resistance and the switch tube are used for slow start, when a short circuit occurs between the power bus bars, can the input circuit be quickly turned off and can it be ensured that the parallel switch tube is not increased rapidly? Current damage is the key to ensuring protection can be achieved. Otherwise, the long-term high current may cause the power supply to smoke or catch fire and cause safety accidents. In particular, the greater the power, the more serious the situation is when there are more switch tubes connected in parallel. Under normal circumstances, to turn off a switch tube (such as a MOS tube) in an on state, its driving voltage (such as a gate-source voltage Vgs) needs to be lowered below its turn-on threshold. Therefore, when a fault occurs, the choice of when to turn off and the time required to turn off determine the timeliness of the protection and the stress requirements on the switching devices.

At present, the conventional approach is: on the one hand, use the single-chip microcomputer to run the control software, and when a fault is detected, output instructions to turn off the switching tube driving voltage; on the other hand, select the switching tube with strong impact resistance. However, on the one hand, using the single-chip microcomputer to run the control software, it takes a long time from the detection of the signal to the software judgment to give the switching instruction, and then to the completion of the switching action of the switch tube; and once a short circuit occurs between the power bus, the current will be A sharp rise in a short period of time may still cause smoke and fire in the power supply and cause safety accidents. On the other hand, because the current will rise sharply in a short time when a fault occurs, even if a switch tube with a large size and strong impact resistance is selected, it cannot fundamentally eliminate the safety hazard of smoke and fire when the power bus is abnormally short-circuited.

Summary of the invention

The embodiments of the present application provide a protection circuit and a power supply for a power supply, which can quickly turn off the slow-start switch tube when a fault occurs, and effectively reduce the stress requirement on the slow-start switch tube.

In the 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, and the protection circuit includes:

The detection module includes a detection input terminal and a detection output terminal, the detection input terminal is electrically connected to the power bus;

The response module includes at least one first switching device configured to control the turning off of the slow-start switch tube, and the control terminal of the first switching device is connected to the detection output terminal.

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

Power input

A power bus, the power bus is connected to a power input end;

Power output

A slow-start circuit, the slow-start circuit is arranged at the power bus bar, and is set as a power slow-start; the slow-start circuit includes a slow-start resistor and a slow-start switch tube connected in parallel;

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

Other features and advantages of the present application will be described in the following description, and partly become obvious from the description, or understood by implementing the present application. The purpose and other advantages of the application can be realized and obtained through the structures specifically pointed out in the specification, claims and drawings.

Description of the drawings

The accompanying drawings are used to provide a further understanding of the technical solution of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application, and do not constitute a limitation to the technical solution of the present application.

Figures 1a, 1b, 1c, and 1d are schematic diagrams of the realization of four commonly used slow-start circuits;

Figure 2 is a schematic diagram of the position and implementation of the slow-start circuit in the switching power supply in the related art;

FIG. 3 is a schematic diagram of the position and implementation of the slow-start circuit structure in the switching power supply of the related art resistor plus MOS tube as the slow-start;

FIG. 4 is a schematic structural diagram of a protection circuit provided by an embodiment of the present application;

5 is a schematic diagram of the position structure of the protection circuit in the power supply provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a protection circuit provided by another embodiment of the present application;

FIG. 7 is a schematic structural diagram of a protection circuit provided by another embodiment of the present application;

FIG. 8 is a schematic diagram of the position structure of the protection circuit in the power supply provided by another embodiment of the present application;

FIG. 9 is a schematic structural diagram of a protection circuit provided by another embodiment of the present application;

FIG. 10 is a schematic structural diagram of a power supply provided by an embodiment of the present application;

FIG. 11 is a schematic structural diagram of a power supply provided by another embodiment of the present application;

Fig. 12 is a schematic diagram of comparison of effects before and after implementation of an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions, and advantages of this application clearer, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not used to limit the present application. In the case of no conflict, the embodiments in the application and the features in the embodiments can be combined with each other arbitrarily.

It should be noted that although the functional module division is carried out in the device schematic diagram, and the logical sequence is shown in the flowchart, in some cases, it can be executed in a different order from the module division in the device or the sequence in the flowchart. Steps shown or described. The terms "first", "second", etc. in the specification and claims and the above-mentioned drawings are used to distinguish similar objects, and not necessarily used to describe a specific order or sequence.

In the power circuit design, in order to limit the impact current, a slow-start circuit is usually designed in the input loop, which can also be called a soft-start circuit. There are four commonly used implementation forms of slow-start circuits: one is resistance for slow start (refer to Figure 1a), the other is MOS transistors for slow start (refer to Figure 1b), and the third is resistance plus relay for slow start (refer to Figure 1c). ), the fourth is a resistance plus a switch tube (such as a MOS tube) for slow start (refer to Figure 1d). For example, Figure 2 illustrates the location and implementation of the slow-start circuit in the switching power supply; Figure 3 illustrates the location and implementation of the slow-start circuit structure in the switching power supply with a resistor and MOS tube in the related art.

For example, the slow-start circuit structure of a related art switching power supply is shown in Figure 3. This circuit structure is usually used in switching power supplies with larger power. The slow-start circuit includes a plurality of slow-start MOS transistors Q1 and a slow-start resistor R1, and a plurality of slow-start MOS transistors Q1 are connected in parallel with the slow-start resistor R1 and driven by the slow-start MOS. The unit (slow-start switch drive circuit) controls the on-off state of each slow-start MOS transistor Q1. This kind of scheme can not only meet the requirement of inrush current limit, but also is very helpful for the improvement of power supply efficiency. This slow-start circuit structure uses the slow-start resistor R1 to limit the surge current during the power-on process. When the voltage of the input bus capacitor on the power bus reaches a certain value, the slow-start MOS drive unit outputs a drive command to control the slow-start The MOS transistor Q1 is turned on; and when a fault (such as a short circuit of the power bus) occurs, the slow-start MOS drive unit outputs a driving command to turn off the slow-start MOS transistor Q1. The slow-start MOS drive unit usually uses a single-chip microcomputer or discrete components to detect the electrical signal of the power bus or the temperature signal of the slow-start circuit to determine the power failure state. It usually takes tens or hundreds of milliseconds from the detection of the electrical signal of the power bus or the temperature signal of the slow-start circuit to the software judgment of the single-chip microcomputer, and then to the drive instruction to the completion of the switching action of the slow-start MOS transistor Q1; Once there is a short circuit between the power bus bars in operation, the current will rise to hundreds of amperes in a short period of tens to hundreds of nanoseconds. Under such a fast situation, the single-chip microcomputer cannot complete the protection action. A large current of hundreds or even thousands of amperes can easily damage the slow-start MOS transistor Q1 and cause a short circuit and cannot disconnect the input circuit. Then the continuous large current will cause the power supply temperature to rise sharply. Therefore, even if the size is large and impact resistant The capable slow-start MOS transistor Q1 cannot fundamentally solve the potential safety hazards of smoke and fire when the power supply is abnormally short-circuited.

Based on this, the embodiments of the present application provide a protection circuit and a power supply for a power supply. Specifically, in view of the problem that the slow-start switch tube is not turned off in time when a short-circuit fault occurs, a major safety hazard may be caused. The embodiment of the present application adds a protection circuit on the basis of the normal switch of the slow-start switch tube, which can be realized in the event of a fault. At the same time, it starts to trigger the turn-off action of the slow-start switch tube, which can quickly turn off the slow-start switch tube when a fault occurs, and effectively reduces the stress requirement on the slow-start switch tube.

It should be noted that in the following various embodiments, the power supply can be a switching power supply or other types of power supply (such as a linear power supply); the power supply can be a DC power supply or an AC power supply. The following only takes the DC switching power supply as an example for description. The slow-start circuit uses a slow-start resistor and a slow-start switch for slow-start. Among them, the slow-start resistance can adopt various types of resistance, such as constant resistance, thermistor, etc.; the slow-start switch tube can adopt various types of switching tubes, such as triode, MOS tube, etc. The number of slow-start resistance and slow-start switch tubes can be set arbitrarily according to the actual situation. In the following, only the slow-start switch tube is a MOS tube and the slow-start resistance is a positive temperature coefficient thermistor as an example. The slow-start resistance and the slow-start switch tube can be set on the positive line (positive input line) of the power bus, or on the negative line (negative input line) of the power bus, or at the same time on the positive and negative lines of the power bus ( The positive line is provided with a slow-start resistance and a slow-start switch tube, while the negative line is also provided with a slow-start resistance and a slow-start switch tube). The following only takes the slow-start resistance and the slow-start switch tube set on the negative line of the power bus as an example. The fault signal can be an electrical fault signal or an over-temperature signal. For example, the detection module can obtain the electrical fault signal by detecting the electrical signal of the power bus; it can also obtain the over-temperature signal by using the temperature sensor to detect the temperature signal of the slow-start switch circuit. The following is only an example for obtaining an electrical fault signal by detecting the electrical signal of the power bus.

In the 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 sub-module integrated in the power supply circuit.

Example 1A

Referring to Figure 4, the protection circuit for the power supply of this example includes:

The fault signal of the power supply is detected by using the detection module; the response module is used to receive the fault signal, and output an action signal according to the fault signal, so as to control the slow-start switch tube of the power supply to be turned off. It realizes that the slow-start switch tube is quickly turned off when a fault occurs, and the stress requirement on the slow-start switch tube is effectively reduced.

In some examples, the power supply includes a power bus and a slow-start switch. The detection module can be set to detect the electrical signal of the power bus. The electrical signal may be a voltage signal or a current signal. In this embodiment, the electrical signal is a voltage signal as an example for description.

In some examples, referring to FIG. 5, the detection module of the protection circuit and the slow-start switch drive circuit of the slow-start switches Q1 to Qn (such as the slow-start MOS drive unit) share the same ground (ie, the protection circuit and the slow-start switch drive circuit reference ground Consistent), the output terminal of the first switching device in the response module can be connected to the control terminals of the slow-start switch transistors Q1 to Qn, and directly drive the slow-start switch transistors Q1 to Qn, so as to control the slow-start switch transistors Q1 to Qn in the event of a fault. Qn turns off.

The following is an application example for illustration.

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 configured to sample the voltage signal. After the first voltage dividing resistor R6 and the second voltage dividing resistor R7 are connected in series, the first voltage dividing resistor R6 and the second voltage dividing resistor R7 are connected in series. One end of the voltage dividing resistor R6 is used as the detection input terminal to connect to the positive line of the power bus, and one end of the second voltage dividing resistor R7 is connected to the negative line of the power bus as the reference ground of the protection circuit, and the reference ground of the protection circuit is located to the left of the slow-start resistor R1. At the side terminal (ie, the network located before the slow-start circuit), the connection node of the first voltage dividing resistor R6 and the second voltage dividing resistor R7 serves as the detection output end of the detection module and is connected to the input end of the response module.

In this application example, the detection output end of the detection module is connected to the input end of the response module; the response module includes at least one first switching device VT1, and the first switching device VT1 is configured to receive the electrical signal , And output an action signal according to the electrical signal to control the slow-start switch 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 judgment and switching actions, such as a triode, a MOS tube, or other devices with a switching function. The number of the first switching device VT1 may be one or multiple. For example, a cascade driving mode of multiple first switching devices may be adopted. In this example, the first switching device VT1 uses a PMOS tube, and the gate of the PMOS tube serves as the control terminal of the response module and the detection output terminal of the detection module (the connection node of the first voltage divider resistor R6 and the second voltage divider resistor R7) connection. 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 to the gate of the PMOS tube, the cathode is connected to the source of the PMOS tube; the anode of the second protection diode D2 is connected to the base of the PMOS tube, and the cathode is connected to the detection output terminal of the detection module (first The connection node of the voltage dividing resistor R6 and the second voltage dividing resistor R7) is connected, that is, the base of the PMOS tube 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 to the negative line of the power bus as The protection circuit is referenced to the ground, and the reference ground of the protection circuit is located at the left end of the slow-start resistor R1 (ie, the network before the slow-start circuit). The source of the PMOS tube is set to output the action signal to the control end of the slow-start switch transistors Q1 to Q4 of the power supply, so as to control the slow-start switch transistors Q1 to Q4 of the power supply to be turned off.

In this application example, when the power supply is working normally, the voltage value obtained by dividing the voltage signal of the power supply bus by the first voltage dividing resistor R6 and the second voltage dividing resistor R7 is a high level. At this time, the PMOS transistor grid and the PMOS transistor source The voltage difference Vgs of the pole is higher than the turn-on threshold voltage, which will turn off the PMOS tube VT1, the action signal output by the PMOS tube VT1 is high, the slow-start switch tubes Q1 to Q4 maintain the on state, and the power supply works normally. After the slow start, when the power bus fails (such as a short circuit between the positive and negative wires of the power bus), the voltage value obtained by dividing the first voltage dividing resistor R6 and the second voltage dividing resistor R7 quickly drops to a low value. At this time, the voltage difference Vgs between the gate of the PMOS tube and the source of the PMOS tube is lower than the turn-on threshold voltage, and the PMOS tube VT1 turns on quickly, pulling the voltage of the control terminals of the slow-start switches Q1 to Q4 to a low level, Therefore, the slow-start switches Q1 to Q4 can be turned off in a short time. The large current at the time of the fault will cause the resistance of the positive temperature coefficient thermistor R1 to rise rapidly, thereby causing the current in the loop to drop rapidly. After that, the power supply will enter the hiccup protection mode following the characteristics of the thermistor.

Since the slow-start switch tube turns off quickly, the peak current of the power bus input loop is limited, and the large current acts for a very short time, so the heat generated is reduced, and the risk of damage to the power supply, smoke and fire is effectively controlled. Moreover, due to the extremely short time of the large current, the electrical stress and thermal stress requirements of the circuit devices are greatly reduced, so that the circuit has reduced the specification requirements for the slow-start switch Q1, so that more economical devices can be selected, which reduces the cost and at the same time. Improved power performance.

In some embodiments, as in the foregoing embodiment 1A, the response module can directly output a control command to drive the slow-start switch to turn off. In other embodiments, such as the following embodiment 1B, the first switching device controls the slow-start switch of the power supply to be turned off through the isolation module and the secondary response module in turn.

Example 1B

Referring to Figure 7, the protection circuit of this example includes:

The detection module is configured to detect the electrical signal of the power bus; the detection module includes a detection input terminal and a detection output terminal, the detection input terminal is electrically connected to the power bus;

The response module includes at least one first switching device, the control terminal of the first switching device is connected to the detection output terminal; the first switching device is configured to receive the electrical signal and output actions according to the electrical signal signal;

An isolation module, the isolation module is connected between the response module and the secondary response module, and is configured to achieve signal isolation;

A secondary response module, the input terminal of the secondary response module is connected to the output terminal of the response module, and the secondary response module is configured to control the slow-start switch Q1 of the power supply to be turned off according to the action signal .

8, in some examples, due to the difference between the reference ground of the detection signal and the reference ground of the drive signal of the slow-start switches Q1 to Qn, that is, the detection module of the protection circuit and the slow start of the slow-start switches Q1 to Qn When the switch drive circuit does not share the ground, isolation processing is required, and the isolation module can be used to realize the signal isolation between the response module and the secondary response module. The isolation module can be implemented by electronic devices with isolation function such as optocoupler U1 and isolation chip U1. The response module controls the slow-start switch tube of the power supply to be turned off through the isolation module and the secondary response module in turn.

For the related description of the detection module, please refer to the corresponding description of Embodiment 1A, which will not be repeated here.

The response module includes at least one first switching device VT1, and the first switching device VT1 is configured to receive the electrical signal and output an action signal according to the electrical signal to control the slow-start switch Q1 of the power supply to turn off Off. The first switching device VT1 is a device (non-software control device) that uses hardware to implement judgment and switching actions, such as a triode, a MOS tube, or other devices with a switching function. The number of the first switching device VT1 may be one or more, for example, a cascade driving mode of multiple first switching devices may be adopted.

The secondary response module includes at least one second switching device VT2. The second switching device VT2 is a device (non-software control device) that uses hardware to implement judgment and switching actions, such as a triode, a MOS tube, or other devices with a switching function. The number of the second switching device VT2 may be one or multiple. For example, a cascade driving mode of multiple second switching devices may be adopted.

Two application examples are described below.

Application example 1B-1

Referring to Figure 9, the protection circuit of this application example can be applied to a high-power (such as 2500W) low-voltage DC power supply. The slow-start circuit uses a positive temperature coefficient thermistor (slow-start resistance R1) and 6 slow-start MOS tubes (slow-start switch tubes) in parallel, and the 6 MOS tubes are the first slow-start MOS tube Q1 to the sixth slow-start MOS tube respectively. Start MOS tube Q6, 6 MOS tubes are all NMOS tubes. In some examples, to quickly turn off the drive of the slow-start MOS transistor, it is generally necessary to extract the gate-source charge of the slow-start MOS transistor with a capacity of several amperes and maintain a 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 configured to sample voltage signals. After the first voltage dividing resistor R6 and the second voltage dividing resistor R7 are connected in series, the first voltage dividing resistor R6 One end of the second voltage divider resistor R7 is connected to the positive line of the power bus, and one end of the second voltage divider resistor R7 is connected to the negative line of the power bus. The connection node of the first voltage divider R6 and the second voltage divider R7 serves as the output end of the detection module and the response The input terminal of the module is connected.

The isolation module is realized by optocoupler U1. The optocoupler U1 includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal.

The response module includes a PNP triode, the emitter of the PNP triode is connected to the second input terminal of the optocoupler U1. The first input terminal of the optocoupler U1 is connected to the first power supply terminal VCC1 through the fifth resistor R5. The collector of the PNP transistor is connected to the reference ground of the detection signal (that is, the right end of the slow-start resistor R1, which is referred to as the primary reference ground of the protection circuit below), and the base is connected to the output terminal of the detection module (the first voltage divider R6 and the first voltage divider resistor R6). The connection node of the voltage divider R7) is connected. 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 to the base of the PNP transistor, the cathode is connected to the emitter of the PNP transistor; the anode of the second protection diode D2 is connected to the base of the PNP transistor, and the cathode is connected to the output terminal of the detection module, namely PNP The base of the triode is connected to the output terminal of the detection module through the second protection diode D2; the collector of the PNP triode is connected to the negative line of the power bus as the primary reference ground of the protection circuit, and the primary reference ground of the protection circuit is located at the slow-start resistor The right end of R1 (that is, the network after the slow-start circuit). The emitter of the PNP transistor is set to output the action signal, and the action signal is transmitted to the secondary response module through the isolation module.

The secondary response module uses a second MOS tube as the second switch tube. Among them, the second MOS tube can choose a small-signal MOS tube (this application example chooses a small-signal NMOS tube) to reduce costs. The secondary response module further includes 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 the fourth resistor R4, and the second output terminal of the optocoupler U1 is connected to the gate of the second MOS transistor. The gate of the second MOS transistor is respectively connected to the drive signal reference ground of the slow-start switch Q1 (that is, the left end of the slow-start resistor R1) through a parallel circuit formed by the third resistor R3 and the second capacitor C2. The source of the second MOS transistor is connected to the reference ground of the drive signal of the slow-start switch Q1, and the drain of the second MOS transistor is connected to the gates of the slow-start MOS transistors Q1 to Q6.

In this example, when the power supply is working normally, the voltage value obtained by dividing the voltage signal of the power bus by the first voltage dividing resistor R6 and the second voltage dividing resistor R7 is a high level (for example, higher than the voltage of the first power supply terminal VCC1), The PNP transistor VT1 will be turned off, and the action signal output by the PNP transistor VT1 will be high. As a result, the optocoupler U1 does not work, the second MOS transistor VT2 is in an off-working state, the slow-start MOS transistors Q1 to Q6 maintain the on state, and the power supply works normally. After the slow start, when the power bus fails (such as a short circuit between the positive and negative wires of the power bus), the voltage value obtained by dividing the first voltage dividing resistor R6 and the second voltage dividing resistor R7 quickly drops to a low value. Level (for example, lower than the voltage of the first power supply terminal VCC1), the PNP transistor VT1 is quickly turned on, and then the optocoupler U1 is turned on, and the second MOS tube VT2 is also quickly turned on, so that it can be within 1 to 2 microseconds. The voltages of the control terminals of the six slow-start MOS transistors Q1 to Q6 in parallel are pulled to a low level, so that the six slow-start MOS transistors Q1 to Q6 are turned off. The large current at the time of the fault will cause the resistance of the positive temperature coefficient thermistor R1 to rise rapidly, thereby causing the current in the loop to drop rapidly. After that, the power supply will enter the hiccup protection mode following the characteristics of the thermistor.

Application example 1B-2

Referring to Figure 10, the protection circuit of this application example can be applied to low-voltage DC power supplies of medium and high power (such as 1500W). The slow-start circuit uses a positive temperature coefficient thermistor (slow-start resistance R1) and 4 slow-start MOS tubes (slow-start switch tubes) in parallel. The 4 MOS tubes are the first slow-start MOS tube Q1 to the fourth slow-start MOS tube respectively. The MOS tube Q4 is turned on, and the 4 MOS tubes are all NMOS tubes. In some examples, to quickly turn off the drive of the slow-start MOS transistor, it is generally necessary to extract the gate-source charge of the slow-start MOS transistor with a capacity of several amperes and maintain a low level for a period of time.

Compared with the application example 1B-1, this application example is applied to a low-power low-voltage DC power supply, so there are fewer slow-start MOS transistors in parallel. The first switching device VT1 uses a PMOS tube, the isolation module uses an isolation chip U1, and the second switching device VT2 uses an NPN transistor. The parameters of the peripheral third resistor R3 and the second capacitor C2 can be actually adjusted according to actual conditions. The rest of the circuit structure of the application example 1B-2 is similar to that of the application example 1B-1, see Figure 9 for details, and will not be repeated here. The protection circuit of application example 1B-2 can also achieve the purpose of quickly turning off the slow-start MOS tube when the power bus fails, thereby protecting the power supply.

Referring to Fig. 12, it illustrates the magnitude and duration of the input loop current Iin when the power supply adopts the embodiment of the present invention before and after the power supply is faulty. Before adding a protection circuit (no protection circuit is used), the slow-start MOS drive unit detects and uses software to turn off the slow-start MOS tube when the fault occurs. The input loop current curve L1 peak current reaches 800A, the loop current peak value is high, and the current action time is T1 Longer, the power supply is easily damaged; after adding a protection circuit (using a protection circuit), the embodiment of the present invention adopts a hardware method to detect the electrical signal of the power bus after the slow start position, and directly drives and closes the slow start MOS tube, and enters the loop current curve L2 The peak current is about 300A, the peak value of the loop current is significantly reduced, and the current action time T2 is shortened, and the reliability of the power supply is improved. Therefore, with the embodiment of the present invention, the slow-start switch Q1 can be quickly turned off when a fault occurs, and the stress requirement on the slow-start switch Q1 can be effectively reduced.

In a second aspect, an embodiment of the present application provides a power supply, which includes the protection circuit as described in the first aspect. The power supply can be a switching power supply or other types of power supply (such as a linear power supply); it can be a DC power supply or an AC power supply. The following only takes the DC power supply as an example for description.

Example 2

Referring to Figure 5 or Figure 8 or Figure 11, the power supply of this example includes:

Power input

A power bus, the power bus is connected to a power input end;

Power output

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

In some examples, the power input terminal is set to access external power supply; the power bus includes a positive line and a negative line, and an input bus capacitor C1 is set between the positive line and the negative line. The detection module of the protection circuit can detect the input bus capacitor C1 The voltage signal (electrical signal) at both ends is used to monitor the working status of the power supply. Obviously, the electrical signal can also be a current signal, power signal, impedance, etc.

In some examples, the power supply is a switching power supply, and the switching power supply further includes a power conversion module connected between the power input terminal and the power output terminal. The power conversion module can be implemented by a commonly used power conversion circuit, which generally includes a circuit that converts a DC voltage into a pulse voltage, or a circuit that converts a DC voltage into a pulse voltage and then into a DC output voltage.

In some examples, the slow-start circuit includes a slow-start MOS driving unit, a slow-start resistor R1, and a slow-start switch Q1. The slow-start MOS driving unit can detect the working state of the power supply by detecting the voltage signal of the power bus, and output a control command to drive the slow-start switch Q1 to control the on-off state of the slow-start switch Q1. Among them, the slow-start MOS drive unit can be implemented by a processor such as a single-chip microcomputer through software processing, or it can be implemented by a pure hardware method composed of discrete devices. The slow-start resistance R1 and the slow-start switch Q1 can be set on the positive line (positive input line) of the power bus, or on the negative line (negative input line) of the power bus, or at the same time on the positive and negative lines of the power bus. Line (the positive line is provided with a slow-start resistance R1 and a slow-start switch tube Q1, while the negative line is also provided with a slow-start resistance R1 and a slow-start switch tube Q1). FIG. 5 or FIG. 8 or FIG. 11 illustrates the power circuit structure in which the slow-start resistance R1 and the slow-start switch tube Q1 are arranged on the negative line of the power bus. Among them, Figure 5 shows that the protection circuit is arranged before the slow-start circuit, the detection module of the protection circuit and the slow-start switch drive circuit of the slow-start switch tube share the same ground (that is, the detection module of the protection circuit and the slow-start switch drive circuit have the same reference ground) Figure 8 or Figure 11 illustrates the power circuit structure in which the protection circuit is set after the slow-start circuit, and the detection module of the protection circuit and the slow-start switch drive circuit of the slow-start switch tube do not share the same ground. The slow-start resistance R1 can adopt various types of resistances, such as constant resistance, thermistor, etc.; the slow-start switch Q1 can adopt various types of switching tubes, such as a triode, a MOS tube, etc. The number of slow-start resistor R1 and slow-start switch Q1 can be set arbitrarily according to actual conditions. Figure 11 shows the 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 a slow-start switch Q1 are connected in parallel. This circuit structure is generally suitable for low power. Figure 8 shows the circuit structure of the slow-start circuit including a slow-start resistor R1 and a plurality of slow-start switches Q1 to Qn, the one slow-start resistor R1 and a plurality of slow-start switches Q1 in parallel, this circuit The structure is generally suitable for power supplies with larger power.

With the power supply of this embodiment, the slow-start switch Q1 can be turned off in microseconds when a fault (such as a short circuit) occurs, thereby limiting the current size and action time in the input loop after the fault occurs, thereby damaging the power supply Effective control of the risk of smoke and fire. In addition, the electrical stress and thermal stress requirements for the slow-start switch Q1 can be effectively reduced, so that the power supply can choose a more economical slow-start switch Q1, which reduces the cost and improves the performance of the power supply.

Referring to FIG. 12, it illustrates the magnitude and duration of the input loop current Iin when the power supply adopts the embodiment of the present invention before and after the power supply is faulty. Before adding the protection circuit (no protection circuit is used), the slow-start MOS drive unit is used to detect the fault and the slow-start MOS tube is turned off by the software. The input loop current curve L1 peak current reaches 800A, the loop current peak value is high, and the current action time T1 Longer, the power supply is easily damaged; after adding a protection circuit (using a protection circuit), the embodiment of the present invention adopts a hardware method to detect the electrical signal of the power bus after the slow start position, and directly drives and closes the slow start MOS tube, and enters the loop current curve L2 The peak current is about 300A, the peak value of the loop current is significantly reduced, and the current action time T2 is shortened, and the reliability of the power supply is improved. Therefore, with the embodiment of the present invention, the slow-start switch Q1 can be quickly turned off when a fault occurs, and the stress requirement on the slow-start switch Q1 can be effectively reduced.

The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

A person of ordinary skill in the art can understand that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit . Such software may be distributed on a computer-readable medium, and the computer-readable medium may include a computer storage medium (or a non-transitory medium) and a communication medium (or a transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile data implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Sexual, removable and non-removable media. Computer storage media include but are not limited to RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or Any other medium used to store desired information and that can be accessed by a computer. In addition, as is well known to those of ordinary skill in the art, communication media usually contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as carrier waves or other transmission mechanisms, and may include any information delivery media. .

The above is a detailed description of the preferred implementation of the application, but the application is not limited to the above-mentioned embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the application. Equivalent modifications or replacements are all included in the scope defined by the claims of this application.

Claims

A protection circuit for a power supply, the power supply includes a slow-start switch tube, and the protection circuit includes:

The detection module includes a detection input terminal and a detection output terminal, the detection input terminal is set to obtain a fault signal of the power supply;

The response module includes at least one first switching device configured to control the turning off of the slow-start switch tube, and the control terminal of the first switching device is connected to the detection output terminal.
The circuit according to claim 1, wherein the fault signal is an electrical fault signal or an over-temperature signal.
The circuit according to claim 1, wherein the output terminal of the first switching device is connected to the control terminal of the slow-start switch.
The circuit according to claim 1, further comprising an isolation module and a secondary response module, and the first switching device controls the slow-start switch of the power supply to be turned off through the isolation module and the secondary response module in turn.
The circuit according to claim 4, wherein the secondary response module comprises at least one second switching device, the control terminal of the second switching device is connected to the output terminal of the isolation module, and the input of the isolation module The terminal is connected to the output terminal of the first switching device, and the output terminal of the second switching device is configured to control the slow-start switch to be turned off.
The circuit according to any one of claims 1 to 5, wherein the first switching device is a triode or a MOS tube.
A power supply including:

Power input

A power bus, the power bus is connected to a power input end;

Power output

A slow-start circuit, the slow-start circuit is arranged at the power bus bar, and is set as a power slow-start; the slow-start circuit includes a slow-start resistor and a slow-start switch tube connected in parallel;

A protection circuit for power supply according to any one of claims 1 to 6.
8. The power supply according to claim 7, wherein the power supply is a switching power supply, and the switching power supply further comprises a power conversion module, and the power conversion module is connected between the power input terminal and the power output terminal.
8. The power supply according to claim 7 or 8, further comprising an input bus capacitor, the input bus capacitor is connected between the power bus, and the detection input terminal is configured to obtain an electrical signal of the input bus capacitor.
The power supply according to claim 7 or 8, wherein the slow start circuit comprises:

A slow-start resistor and a slow-start switch tube, the one slow-start resistor and one slow-start switch tube are connected in parallel;

or,

A slow-start resistor and a plurality of slow-start switch tubes, and the one slow-start resistor and the plurality of slow-start switch tubes are connected in parallel;

or,

Multiple slow-start resistors and one slow-start switch tube, the multiple slow-start resistors and one slow-start switch tube are connected in parallel;

or,

A plurality of slow-start resistors and a plurality of slow-start switch tubes, and the plurality of slow-start resistors and the plurality of slow-start switch tubes are connected in parallel.