A constant current source circuit, a switch device and a terminal

Abstract

The embodiment of the present invention discloses a constant current source circuit, a switch device and a terminal. The constant current source circuit includes a step-down module, a voltage stabilizing module and a control module; the control module is connected to the step-down module and the voltage stabilizing module respectively, the step-down module is connected to the power supply and the control module, and the step-down module is used to step down the voltage of the power supply into a first voltage signal according to the first instruction of the control module; the voltage stabilizing module is electrically connected to the step-down module and the control module respectively, and the voltage stabilizing module is used to stably output the first voltage signal into a stable first current signal according to the second instruction of the control module. The technical solution of the present invention is that the step-down module outputs a stable first current signal according to the first instruction of the control module and the voltage stabilizing module outputs a stable first current signal according to the second instruction of the control module, so that the fuse resistor is melted, and the contact switch is disconnected at the same time, thereby disconnecting the high-voltage busbar of the power battery, so as to avoid dangerous situations that may occur due to abnormalities of the power battery and protect the safety of passengers and vehicles.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power battery management systems, and in particular to a constant current source circuit, a switch device, and a terminal. Background Art

[0002] In recent years, new energy vehicles, especially pure electric vehicles, have gradually become popular in the market, and the safety issues caused by the power batteries in pure electric vehicles have also attracted more and more attention from automobile companies and consumers. The power battery is the only power source for pure electric vehicles, and its voltage is often very high, reaching 400V to 500V. In high temperature and high humidity environments, or when the vehicle is involved in a collision accident or system failure, the battery may explode or burn, seriously endangering the lives of drivers and passengers. Summary of the invention

[0003] The embodiments of the present invention provide a constant current source circuit, a switch device and a terminal to solve the problem that a power battery is prone to danger under abnormal conditions.

[0004] In order to achieve the above technical problems, the present invention adopts the following technical solutions:

[0005] In a first aspect, an embodiment of the present invention provides a constant current source circuit, the constant current source circuit comprising:

[0006] Buck module, voltage stabilization module and control module;

[0007] The control module is connected to the step-down module and the voltage stabilization module respectively.

[0008] The voltage reduction module is connected to the power supply and the control module, and is used to reduce the voltage of the power supply to a first voltage signal according to a first instruction of the control module;

[0009] The voltage stabilizing module is electrically connected to the step-down module and the control module respectively, and the voltage stabilizing module is used to output the first voltage signal as a stable first current signal according to the second instruction of the control module; wherein the first instruction and the second instruction are triggered when it is determined that a fault has occurred and the high-voltage bus of the power battery needs to be disconnected.

[0010] Optionally, the buck module includes: a DC-DC buck unit and a first resistor network;

[0011] The control end of the DC-DC step-down unit is connected to the first signal end of the control module, the first end of the DC-DC step-down unit is connected to the power supply, the second end of the DC-DC step-down unit is connected to the first end of the first resistor network, the second end of the first resistor network is connected to the input end of the voltage stabilizing module, and the third end of the first resistor network is grounded.

[0012] Optionally, the first resistor network includes:

[0013] A first resistor and a second resistor, wherein the first end of the first resistor is connected to the input end of the voltage stabilizing module; the second end of the first resistor is connected to the first end of the second resistor and the second end of the DC-DC buck unit; and the second end of the second resistor is grounded.

[0014] Optionally, the voltage stabilizing module includes a power port unit, a voltage stabilizing unit and a second resistor network;

[0015] The input end of the power port unit is connected to the output end of the step-down module, the output end of the power port unit is electrically connected to the input end of the voltage stabilizing unit, and the control end of the power port unit is connected to the second signal end of the control module;

[0016] The output end of the voltage stabilizing unit is connected to the input end of the second resistor network, and the output end of the second resistor network is connected to the output interface of the constant current source circuit.

[0017] Optionally, the power port unit comprises a third resistor network, a first switch component and a second switch component;

[0018] The control end of the first switch component is connected to the second signal end of the control module, the first end of the first switch component is respectively connected to the first end of the third resistor network and the control end of the second switch component; the second end of the first switch component is grounded; the second end of the third resistor network is respectively connected to the output end of the step-down module and the first end of the second switch component, and the second end of the second switch component is connected to the input end of the voltage stabilizing unit.

[0019] Optionally, the power port unit further comprises:

[0020] A fourth resistor network, wherein a first end of the fourth resistor network is connected to the control end of the first switch component, and a second end of the fourth resistor network is grounded.

[0021] Optionally, the voltage stabilizing unit includes a first voltage stabilizing component and a second voltage stabilizing component;

[0022] The input end of the first voltage stabilizing component is connected to the input end of the second voltage stabilizing component; the output end of the first voltage stabilizing component is connected to the output end of the second voltage stabilizing component.

[0023] Optionally, the second resistor network includes:

[0024] a third resistor, a fourth resistor and a fifth resistor;

[0025] A first end of the third resistor is connected to a first output end of the first voltage stabilizing component;

[0026] A first end of the fourth resistor is connected to a first output end of the second voltage stabilizing component;

[0027] A first end of the fifth resistor is connected to the second output end of the first voltage stabilizing component and the second output end of the second voltage stabilizing component respectively;

[0028] The second end of the third resistor is connected to the second end of the fourth resistor and the second end of the fifth resistor, and is connected to the output interface of the constant current source circuit.

[0029] In a second aspect, an embodiment of the present invention provides a switch device, comprising any constant current source circuit according to the first aspect, a contact switch and a fuse resistor;

[0030] The contact switch is connected in series with the high-voltage busbar of the power battery; the output interface of the constant current source circuit is connected to the first end of the fuse resistor, and the second end of the fuse resistor is grounded;

[0031] When it is determined that there is no fault, the constant current source circuit outputs a stable second current signal, and the fuse resistor closes the contact switch according to the second current signal;

[0032] When it is determined that a fault occurs, the constant current source circuit outputs a stable first current signal, the fuse resistor is blown according to the first current signal, and the contact switch is powered off and opened.

[0033] In a third aspect, an embodiment of the present invention provides a terminal, comprising any constant current source circuit of the first aspect, or comprising a switching device of the second aspect.

[0034] The technical solution provided by the present invention is that the constant current source circuit reduces the voltage of the power supply to a first voltage signal through the step-down module according to the first instruction of the control module; the voltage stabilizing module outputs the first voltage signal as a stable first current signal according to the second instruction of the control module, so that the voltage stabilizing module can melt the fuse resistor by outputting the stable first current signal, and at the same time disconnect the contact switch, thereby disconnecting the high-voltage busbar of the power battery, so that the power battery no longer outputs voltage to the outside, so as to avoid dangerous situations that may occur due to abnormal power batteries, and protect the safety of passengers and vehicles. On the other hand, the constant current source circuit provided in this embodiment outputs a stable first current signal, so that the fuse resistor can receive the stable first current signal, so that the fuse resistor can reliably melt when it is determined that a fault occurs, thereby improving the power supply safety and reliability of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0036] Figure 1It is a structural schematic diagram of a constant current source circuit provided by an embodiment of the present invention;

[0037] Figure 2 is a structural schematic diagram of another constant current source circuit provided by an embodiment of the present invention;

[0038] Figure 3 is a structural schematic diagram of another constant current source circuit provided by an embodiment of the present invention;

[0039] Figure 4 is a structural schematic diagram of another constant current source circuit provided by an embodiment of the present invention;

[0040] Figure 5 is a structural schematic diagram of another constant current source circuit provided by an embodiment of the present invention;

[0041] Figure 6 is a structural schematic diagram of a switch device provided by an embodiment of the present invention;

[0042] Figure 7 is a schematic diagram of the structure of a terminal provided by an embodiment of the present invention;

[0043] Figure 8 It is a schematic diagram of the structure of another terminal provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0045] Based on the above technical problems, this embodiment proposes the following solutions:

[0046] Figure 1 Schematic diagram of a constant current source circuit provided by an embodiment of the present invention. Figure 1 The constant current source circuit provided by the embodiment of the present invention includes a step-down module 10, a voltage stabilizing module 20 and a control module 30; the control module 30 is respectively connected to the step-down module 10 and the voltage stabilizing module 20, the step-down module 10 is connected to the power supply and the control module 30, the step-down module 10 is used to step down the voltage of the power supply into a first voltage signal according to a first instruction of the control module 30; the voltage stabilizing module 20 is respectively electrically connected to the step-down module 10 and the control module 30, the voltage stabilizing module 20 is used to output the first voltage signal into a stable first current signal according to a second instruction of the control module 30; wherein the first instruction and the second instruction are triggered when it is determined that a fault occurs and the high-voltage bus of the power battery needs to be disconnected.

[0047] Specifically, the constant current source circuit can provide a current signal for the circuit breaker connected in series on the high-voltage bus of the power battery. When the control module 30 detects abnormal working conditions such as a collision accident or a system failure of a terminal such as a vehicle, it is determined that a failure has occurred and the high-voltage bus of the power battery needs to be disconnected to ensure the safety of the terminal such as the vehicle. The first instruction and the second instruction are triggered when it is determined that a failure has occurred and the high-voltage bus of the power battery needs to be disconnected. The first instruction and the second instruction are issued by the control module 30.

[0048] The step-down module 10 is connected to the power supply. The step-down module 10 can step down the DC voltage provided by the power supply into a first voltage signal according to the first instruction output by the control module 30, so as to provide the required power supply for the voltage stabilizing module 20. For example, the DC voltage provided by the power supply can be a 12V DC voltage. After being stepped down by the step-down module 10, the output first voltage signal can be a 5V DC voltage. According to the second instruction output by the control module 30, the voltage stabilizing module 20 outputs the first voltage signal as a stable first current signal. It should be noted that the first instruction and the second instruction can be level signals, and the first instruction and the second instruction can be the same or different. For example, the first instruction can be a high level signal, and the second instruction can be a low level signal, which is not limited here.

[0049] For example, the output terminal I of the voltage stabilizing module 20 is OUT It can be connected to the fuse resistor 40, and the contact switch 50 can be a contact switch 50 that controls high voltage with low voltage. The fuse resistor 40 controls the low voltage part of the contact switch 50, and the contact switch 50 controls the high voltage part. The contact switch 50 can be connected in series to the high voltage bus of the power battery.

[0050] It can be arranged that, when the power battery is working normally, the constant current source circuit can provide a small current to the fuse resistor 40, so that the coil where the fuse resistor 40 is located is powered on, so that the contact switch 50 is attracted, and the high-voltage bus of the power battery is powered normally.

[0051] When the power battery is working abnormally, the first current signal output by the voltage stabilizing module 20 can be a constant current. The first current signal is greater than the fusing current of the fuse resistor 40. The fuse resistor 40 will be blown due to excessive power, so that the coil where the fuse resistor 40 is located is de-energized, and the contact switch 50 is disconnected, thereby disconnecting the high-voltage bus of the power battery.

[0052] The constant current source circuit provided in this embodiment reduces the voltage of the power supply to a first voltage signal through the step-down module according to the first instruction of the control module; the voltage stabilizing module outputs the first voltage signal as a stable first current signal according to the second instruction of the control module, so that the voltage stabilizing module outputs the stable first current signal to make the fuse resistor melt, and at the same time disconnects the contact switch 50, thereby disconnecting the high-voltage busbar of the power battery, so that the power battery no longer outputs voltage to the outside, so as to avoid dangerous situations that may occur due to abnormalities of the power battery, and protect the safety of passengers and vehicles. On the other hand, the constant current source circuit provided in this embodiment outputs a stable first current signal, so that the fuse resistor can receive the stable first current signal, so that the fuse resistor can be reliably melted when a fault is determined, thereby improving the power supply safety and reliability of the power battery.

[0053] Optional, Figure 2 FIG. 1 is a schematic diagram of another constant current source circuit provided by an embodiment of the present invention. Based on the above embodiment, see Figure 2 The step-down module 10 may include a DC-DC step-down unit 101 and a first resistor network 102; the control end of the DC-DC step-down unit 101 is connected to the first signal end of the control module 30, the first end of the DC-DC step-down unit 101 is connected to the power supply, the second end of the DC-DC step-down unit 101 is connected to the first end of the first resistor network 102, the second end of the first resistor network 102 is connected to the input end of the voltage stabilizing module 20, and the third end of the first resistor network 102 is grounded.

[0054] Specifically, the DC-DC buck unit 101 can select the chip TLS4120D0, which has a maximum continuous output current of 2A, an input voltage range of 3.7V to 40V, an adjustable output voltage range of 3V to 10V, and a switching frequency range of 320khz to 560khz or 1.6MHz to 2.8MHz. The control module 30 can be adjusted in a pulse width modulation mode.

[0055] The first end of the DC-DC step-down unit 101 is connected to a power supply, and the power supply provides a 12V voltage to power the chip TLS4120D0. The enable pin EN of the chip TLS4120D0 is connected to the first signal end of the control module 30, and the control module 30 can be a single-chip microcomputer. The control module 30 controls the output of the chip TLS4120D0 to be controllable.

[0056] When the control module 30 outputs a high level, the chip TLS4120D0 starts working and outputs a first voltage signal. When the control module 30 outputs a low level, the chip TLS4120D0 stops working and has no output. The EN pin is grounded through a resistor to ensure that when there is no high level signal from the control module 30, the chip TLS4120D0 can remain disabled to prevent accidental activation. The SYNC pin of the chip TLS4120D0 is grounded through a resistor.

[0057] The pin SW of the chip TLS4120D0 can be connected to a step-down converter circuit, which includes a first inductor L1, a first capacitor C1, and a second capacitor C2. The first inductor L1 of the step-down converter circuit can be selected to have an inductance of 22uH. The first capacitor C1 can be selected to have a capacitance of 100nF, and the first capacitor C1 is mainly used to filter out high-frequency interference in the power supply. The second capacitor C2 can be selected to have a capacitance of 22uF, and is mainly used to filter out low-frequency interference in the power supply.

[0058] It should be noted that the inductance of the first inductor L1 should be selected in accordance with the switching frequency of the chip TLS4120D0. The switching frequency of this chip is determined by the resistance of the external pull-down resistor of the pin FREQ, which can also be left floating, which is equivalent to the infinite resistance of the pin FREQ of the chip TLS4120D0 to the ground. At this time, the switching frequency of the chip TLS4120D0 is 2.2MHz. The higher the switching frequency, the faster the switching rate. This switching frequency setting can ensure that the chip TLS4120D0 will not generate a lot of heat during frequent switching.

[0059] Optionally, referring to 2, the first resistor network 102 may include: a first resistor R1 and a second resistor R2, wherein the first end of the first resistor R1 is connected to the input end of the voltage stabilizing module 20; the second end of the first resistor R1 is connected to the first end of the second resistor R2 and the second end of the DC-DC step-down unit 101; and the second end of the second resistor R2 is grounded.

[0060] Specifically, the output voltage of the chip TLS4120D0 can be adjusted by connecting the first resistor R1 and the second resistor R2 of the voltage divider resistor of the pin FB of the chip TLS4120D0, and the calculation formula is:

[0061]

[0062] Among them, VCC is the expected output voltage of the chip TLS4120D0, V FB The typical value of is 0.8V, the resistance of the first resistor R1 can be 100KΩ, and the resistance of the second resistor R2 can be 17.8KΩ, so the VCC voltage is 5.29V.

[0063] Optionally, Figure 3is a structural diagram of another constant current source circuit provided by an embodiment of the present invention, see Figure 3 On the basis of the above embodiment, the voltage stabilizing module 20 may include a power port unit 201, a voltage stabilizing unit 202 and a second resistor network 203; the input end of the power port unit 201 is connected to the output end of the step-down module 10, the output end of the power port unit 201 is electrically connected to the input end of the voltage stabilizing unit 202, and the control end of the power port unit 201 is connected to the second signal end of the control module 30; the output end of the voltage stabilizing unit 202 is connected to the input end of the second resistor network 203, and the output end of the second resistor network 203 is connected to the output interface of the constant current source circuit.

[0064] Specifically, the power supply is first stabilized by the power port unit 201. The power port unit 201 can be used to prevent the circuit from being reversely conducted. The power port unit 201 can also be used to enable. The first voltage signal is input into the voltage stabilizing unit 202 through the power port unit 201. The voltage stabilizing unit 202 can select a low-difference linear regulator. The voltage stabilizing unit 202 can be a chip LT3080 or a combination of chips LT3080. The chip LT3080 can provide a wide output voltage range alone or in combination. By changing the resistance value of the pin SET of the chip LT3080, the output voltage can be adjusted between 0 and 36V. The second resistor network 203 is used to adjust the current output by the voltage stabilizing unit 202.

[0065] Optionally, Figure 4 FIG. 1 is a schematic diagram of a constant current source circuit provided by an embodiment of the present invention. Based on the above embodiment, see Figure 4 The power port unit 201 may include a third resistor network 2011, a first switch component 2012 and a second switch component 2013; the control end of the first switch component 2012 is connected to the second signal end of the control module 30, and the first end of the first switch component 2012 is respectively connected to the first end of the third resistor network 2011 and the control end of the second switch component 2013; the second end of the first switch component 2012 is grounded; the second end of the third resistor network 2011 is respectively connected to the output end of the step-down module 10 and the first end of the second switch component 2013, and the second end of the second switch component 2013 is connected to the input end of the voltage stabilizing unit 202.

[0066] Optionally, continue to see Figure 4 The power port unit 201 may further include: a fourth resistor R4 network 2014, a first end of the fourth resistor R4 network 2014 is connected to the control end of the first switch component 2012, and a second end of the fourth resistor network 2014 is grounded.

[0067] Specifically, the first switch component 2012 can be a transistor Q1, the second switch component 2013 can be a MOS transistor Q2, and the MOS transistor Q2 can be a P-type MOS transistor. The control end of the transistor Q1 is connected to the second signal end of the control module 30. When the voltage stabilizing unit 202 needs to be powered on, the control module 30 sends a high-level signal to meet the conduction threshold voltage of the transistor Q1, and the transistor Q1 is turned on. At this time, the MOS transistor Q2 reaches the conduction condition, and the MOS transistor Q2 is turned on, and the voltage stabilizing unit 202 is powered. The power port unit 201 uses the PN junction of the MOS transistor Q2 to conduct a large current, and the body parasitic diode of the MOS transistor Q2 can also prevent the power supply from being reversed. The fourth resistor network 2014 adjusts the voltage signal sent by the control module 30 through voltage division.

[0068] Optionally, Figure 5 FIG. 1 is a schematic diagram of a constant current source circuit provided by an embodiment of the present invention. Based on the above embodiment, see Figure 5 The voltage stabilizing unit 202 may include a first voltage stabilizing component LDO1 and a second voltage stabilizing component LDO2; an input end of the first voltage stabilizing component LDO1 is connected to an input end of the second voltage stabilizing component LDO2; and an output end of the first voltage stabilizing component LDO1 is connected to an output end of the second voltage stabilizing component LDO2.

[0069] Optionally, continue to see Figure 5 , the second resistor network 203 may include: a third resistor R3, a fourth resistor R4 and a fifth resistor R5. The first end of the third resistor R3 is connected to the first output end of the first voltage stabilizing component LDO1; the first end of the fourth resistor R4 is connected to the first output end of the second voltage stabilizing component LDO2; the first end of the fifth resistor R5 is connected to the second output end of the first voltage stabilizing component LDO1 and the second output end of the second voltage stabilizing component LDO2 respectively; the second end of the third resistor R3 is connected to the second end of the fourth resistor R4 and the second end of the fifth resistor R5, and is connected to the output interface of the constant current source circuit.

[0070] Specifically, the first voltage stabilizing component LDO1 and the second voltage stabilizing component LDO2 can be used in parallel to increase the output current. The first voltage stabilizing component LDO1 and the second voltage stabilizing component LDO2 can select the chip LT3080. The second resistor network 203 calculates the power of the resistor according to the resistance value and the current size, and selects a wide-edge resistor or a power resistor product with sufficient power and good heat dissipation to avoid overheating of the resistor.

[0071] For example, since the required current of this embodiment is greater than 1.75A, two LT3080 chips are used in parallel for output. The pin IN of the chip LT3080 is connected to the output end of the power port unit 201 to receive the voltage signal output by the power port unit 201, and the pin SET of the chip LT3080 is connected to the fifth resistor R5 to adjust the output current IOUT The resistance values ​​of the third resistor R3 and the fourth resistor R4 can be 1.4Ω, the resistance value of the fifth resistor R5 can be 123.1KΩ, and the pin OUT of the chip LT3080 outputs a voltage V OUT and the output current I OUT The calculation formula is:

[0072] V OUT =10μA×R5=10μA×123.1KΩ=1.231V

[0073] The output current of a single chip LT3080 is:

[0074]

[0075] Output current I of the constant current source circuit after parallel connection OUT for:

[0076] I OUT =I1+I2=1.76A

[0077] Wherein, I1 represents the output current of the first voltage stabilizing component LDO1, and I2 represents the output current of the second voltage stabilizing component LDO2.

[0078] Figure 6 is a schematic diagram of a switch device provided by an embodiment of the present invention, see Figure 6 The switch device 200 includes any constant current source circuit 100 of the above-mentioned embodiment, a contact switch 50 and a fuse resistor 40. The contact switch 50 is connected in series with the high-voltage busbar of the power battery; the output interface of the constant current source circuit is connected to the first end of the fuse resistor 40, and the second end of the fuse resistor 40 is grounded; when it is determined that there is no fault, the constant current source circuit outputs a stable second current signal, and the fuse resistor 40 closes the contact switch 50 according to the second current signal; when it is determined that a fault occurs, the constant current source circuit outputs a stable first current signal, the fuse resistor 40 is melted according to the first current signal, and the contact switch 50 is powered off and opened.

[0079] Specifically, the fuse resistor 40 can select a fixed value resistor of 2Ω. The fuse resistor 40 is connected in series to the high-voltage busbar of the power battery. After each system is powered on, a constant current of 10mA is provided for self-test of the fuse resistor 40 to detect whether the 2Ω resistance in the fuse resistor 40 is normal. When it is determined that there is no fault, the constant current source circuit outputs a stable second current signal. The fuse resistor 40 is energized according to the second current signal, and the contact switch 50 is closed, and the power battery is powered normally. When a fault is detected, the constant current source circuit outputs a stable first current signal, and the contact switch 50 is powered off and opened. The first current signal can be a constant current of 1.75A. The fuse resistor 40 is melted according to the first current signal, and the contact switch 50 triggers the high-voltage part to disconnect, thereby achieving the effect of disconnecting the high-voltage busbar of the power battery.

[0080] Figure 7 is a schematic diagram of the structure of a terminal provided by an embodiment of the present invention, see Figure 7 , the terminal 300 includes any constant current source circuit 100 of the above embodiment, or, Figure 8 is a schematic diagram of the structure of another terminal provided by an embodiment of the present invention, see Figure 8 , including the switch device 200 of the above embodiment.

[0081] Specifically, the constant current source circuit 100 provided in the embodiment of the present invention can be used in a terminal 200, such as an electric vehicle, and the switch device 200 provided in the embodiment of the present invention can also be used in a terminal 300. The terminal can include a vehicle, a drone, an airplane, and the like.

[0082] The switching device or / and terminal device provided in the embodiment of the present invention includes any constant current source circuit of any of the above embodiments, and therefore has the beneficial effects of the above constant current source circuit, which will not be described in detail here.

[0083] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A switch device, characterized in that: include: Constant current source circuit, contact switch and fuse resistor; The contact switch is connected in series with the high-voltage busbar of the power battery; the output interface of the constant current source circuit is connected to the first end of the fuse resistor, and the second end of the fuse resistor is grounded; When it is determined that there is no fault, the constant current source circuit outputs a stable second current signal, and the fuse resistor closes the contact switch according to the second current signal; When it is determined that a fault occurs, the constant current source circuit outputs a stable first current signal, the fuse resistor is blown according to the first current signal, and the contact switch is powered off and opened; Wherein, the constant current source circuit comprises: Buck module, voltage stabilization module and control module; The control module is connected to the voltage reduction module and the voltage stabilization module respectively. The voltage reduction module is connected to the power supply and the control module, and is used to reduce the voltage of the power supply to a first voltage signal according to a first instruction of the control module; The voltage stabilizing module is electrically connected to the step-down module and the control module respectively, and is used to output the first voltage signal as a stable first current signal according to a second instruction of the control module; wherein the first instruction and the second instruction are triggered when it is determined that a fault has occurred and the high-voltage bus of the power battery needs to be disconnected.

2. The switch device according to claim 1, characterized in that: The step-down module comprises: a DC-DC step-down unit and a first resistor network; The control end of the DC-DC step-down unit is connected to the first signal end of the control module, the first end of the DC-DC step-down unit is connected to the power supply, the second end of the DC-DC step-down unit is connected to the first end of the first resistor network, the second end of the first resistor network is connected to the input end of the voltage stabilizing module, and the third end of the first resistor network is grounded.

3. The switch device according to claim 2, characterized in that: The first resistor network comprises: A first resistor and a second resistor, wherein the first end of the first resistor is connected to the input end of the voltage stabilizing module; the second end of the first resistor is connected to the first end of the second resistor and the second end of the DC-DC step-down unit; and the second end of the second resistor is grounded.

4. The switch device according to claim 1, characterized in that: The voltage stabilizing module includes a power port unit, a voltage stabilizing unit and a second resistor network; The input end of the power port unit is connected to the output end of the step-down module, the output end of the power port unit is electrically connected to the input end of the voltage stabilizing unit, and the control end of the power port unit is connected to the second signal end of the control module; The output end of the voltage stabilizing unit is connected to the input end of the second resistor network, and the output end of the second resistor network is connected to the output interface of the constant current source circuit.

5. The switch device according to claim 4, characterized in that: The power port unit includes a third resistor network, a first switch component and a second switch component; The control end of the first switch component is connected to the second signal end of the control module, the first end of the first switch component is respectively connected to the first end of the third resistor network and the control end of the second switch component; the second end of the first switch component is grounded; the second end of the third resistor network is respectively connected to the output end of the step-down module and the first end of the second switch component, and the second end of the second switch component is connected to the input end of the voltage stabilizing unit.

6. The switch device according to claim 5, characterized in that: The power port unit also includes: A fourth resistor network, wherein a first end of the fourth resistor network is connected to the control end of the first switch component, and a second end of the fourth resistor network is grounded.

7. The switch device according to claim 4, characterized in that: The voltage stabilizing unit includes a first voltage stabilizing component and a second voltage stabilizing component; The input end of the first voltage stabilizing component is connected to the input end of the second voltage stabilizing component; the output end of the first voltage stabilizing component is connected to the output end of the second voltage stabilizing component.

8. The switch device according to claim 7, characterized in that: The second resistor network comprises: a third resistor, a fourth resistor and a fifth resistor; The first end of the third resistor is connected to the first output end of the first voltage stabilizing component; The first end of the fourth resistor is connected to the first output end of the second voltage stabilizing component; The first end of the fifth resistor is connected to the second output end of the first voltage stabilizing component and the second output end of the second voltage stabilizing component respectively; The second end of the third resistor is connected to the second end of the fourth resistor and the second end of the fifth resistor, and is connected to the output interface of the constant current source circuit.

9. A terminal, characterized in that: include: A switchgear as claimed in any one of claims 1 to 8.

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