Driving circuit of safety switch, low-voltage battery power supply system and vehicle power system

Abstract

The invention belongs to the technical field of vehicle-mounted power supplies, and particularly relates to a driving circuit of a safety switch of a low-voltage battery, a low-voltage battery power supply system and a vehicle power system, and the driving circuit comprises a driving module with a reference end used for being connected with a source electrode of the safety switch; one end of the first limiting resistor is connected with the output end of the driving module, and the other end is connected with the grid of the safety switch; one end of the limiting capacitor is connected with the other end of the first limiting resistor, and the other end is connected with the reference end of the driving module; wherein the resistance value of the first limiting resistor at least exceeds a preset first threshold value, and the capacitance value of the limiting capacitor at least exceeds the capacitance value of the safety switch input capacitor with a preset first multiplying power, so that when the driving module outputs the driving electric signal, the complete turn-on time of the safety switch is delayed. According to the invention, the linear working area of the safety switch is prolonged, so that the rapid increase of the drain current is inhibited, the triggering of a reverse overcurrent fault is prevented, and the charging of an inner capacitor is not interrupted.

Description

Technical Field

[0001] This invention belongs to the field of vehicle power technology, specifically relating to a driving circuit for a safety switch of a low-voltage battery, a low-voltage battery power supply system, and a vehicle power system. Background Technology

[0002] With the development of automotive electronics, the requirements for reliability and safety are becoming increasingly stringent. Therefore, a protection circuit to prevent short circuits on the low-voltage battery side is typically required. This necessitates the introduction of a power MOSFET as a disconnect device in case of a fault, i.e., a safety switch S connected to the low-voltage battery side. (See reference...) Figure 1 As shown. This also leads to the introduction of the internal capacitor C of the safety switch S. in The precharge overcurrent problem.

[0003] Currently, the commonly used solution is the pre-charge Chopper scheme, which sends a PWM wave to the safety switch S, intermittently turning it on through multiple short pulses, and turning it off in time before the charging current of a single pulse becomes too large. This way, Chopper... in The capacitor is gradually charged over multiple switching cycles. In each switching cycle, when the safety switch S is closed, the inner capacitor C... in The voltage difference between the low-voltage battery and the previous cycle is decreasing, and the charging current in each cycle gradually decreases, thereby avoiding the problem of excessive reverse current triggering overcurrent faults.

[0004] However, the pre-charge Chopper scheme is relatively complex to control. The switching speed of the safety switch S is affected by the output delay of the drive circuit and the parasitic parameters of the safety switch S itself. If the given switching pulse is too long or the safety switch S turns off too slowly, it will still lead to excessive reverse current. In addition, since the capacitor charging current is large when the safety switch S switches on the first pulse, and the current change rate is high when it turns off on the first pulse, the induced voltage generated by the stray inductance on the line may be superimposed on the safety switch S, which may cause the voltage at the terminal of the switch S to be too high and break down. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the present invention aims to provide a driving circuit for a safety switch of a low-voltage battery, which suppresses the drain current i by extending the linear operating region of the safety switch S. D The rapid increase in voltage also suppresses the rapid increase in reverse current, preventing the triggering of reverse overcurrent faults and ensuring that the inner capacitor C is not interrupted. in Charging.

[0006] To achieve the above and other related objectives, the present invention provides a driving circuit for a safety switch of a low-voltage battery, comprising: a driving module, the reference terminal of which is connected to the source of the safety switch; a first limiting resistor, one end of which is connected to the output terminal of the driving module and the other end of which is connected to the gate of the safety switch; and a limiting capacitor, one end of which is connected to the other end of the first limiting resistor and the other end of which is connected to the reference terminal of the driving module; wherein the resistance value of the first limiting resistor at least exceeds a preset first threshold, and the capacitance value of the limiting capacitor at least exceeds the capacitance value of the input capacitor of the safety switch by a preset first multiple, so as to delay the full turn-on time of the safety switch when the driving module outputs a driving electrical signal.

[0007] According to a specific embodiment of the present invention, the device further includes: a second limiting resistor, one end of which is connected to the other end of the first limiting resistor and one end of the limiting capacitor, and the other end of which is used to connect to the gate of the safety switch; an accelerating resistor, one end of which is connected to the output terminal of the driving module and one end of the first limiting resistor; an accelerating capacitor, one end of which is connected to the other end of the accelerating resistor and the other end of which is connected to the reference terminal of the driving module; and an accelerating switch, which is connected in parallel with the first limiting resistor and the second limiting resistor, and a control terminal is connected between the accelerating resistor and the accelerating capacitor; wherein the resistance value of the second limiting resistor at least exceeds a preset second threshold; and the product of the resistance value of the accelerating resistor and the capacitance value of the accelerating capacitor at least exceeds the product of the resistance value of the first limiting resistor and the capacitance value of the limiting capacitor, so that the voltage of the accelerating capacitor can reach the voltage level of the driving signal after the limiting capacitor is fully charged, and the accelerating switch is turned on.

[0008] According to a specific embodiment of the present invention, the acceleration switch is a MOS transistor, and its drain is connected to one end of the first limiting resistor, and its source is connected to the other end of the second limiting resistor; wherein, when the voltage of the acceleration capacitor reaches the voltage of the driving signal, the voltage of the gate of the acceleration switch is higher than the voltage of the source, and the voltage difference between the gate and the source exceeds the turn-on threshold, so that the acceleration switch is turned on.

[0009] According to a specific embodiment of the present invention, the acceleration switch is further configured with a body diode; wherein, the gate of the safety switch can be quickly grounded from the internal circuit of the driving module through the body diode of the acceleration switch, so as to realize the rapid turn-off of the safety switch.

[0010] According to a specific embodiment of the present invention, it further includes: an adjusting resistor, one end of which is connected to the other end of the second limiting resistor, and the other end of which is used to connect to the gate of the safety switch; wherein, the turning-off speed of the safety switch can be adjusted by adjusting the resistance value of the adjusting resistor.

[0011] According to a specific embodiment of the present invention, the resistance values ​​of the first limiting resistor and the second limiting resistor are at least greater than the resistance value of the adjusting resistor by a preset second multiplier.

[0012] According to a specific embodiment of the present invention, after the acceleration switch is turned on, it can be quickly turned on again after the safety switch is turned off within a preset time; wherein, the preset time is related to the discharge time of the acceleration capacitor.

[0013] According to a specific embodiment of the present invention, it further includes: a gate-source resistor for connecting between the gate and the source of the safety switch.

[0014] A low-voltage battery power supply system includes a drive circuit for a safety switch, a low-voltage battery, a safety switch, and a DC / DC converter; wherein a capacitor is connected in parallel to the input / output terminals of the DC / DC converter; the positive terminal of the low-voltage battery is connected to the drain of the safety switch, and the negative terminal is connected to the other end of the capacitor; the source of the safety switch is connected to one end of the capacitor, and the gate is connected to the drive circuit.

[0015] According to a specific embodiment of the present invention, it further includes: a current sampling resistor connected in series on one side of the safety switch.

[0016] A vehicle power system includes the low-voltage battery power supply system described above.

[0017] This invention provides a driving circuit for a safety switch of a low-voltage battery. By extending the linear operating region of the safety switch during its initial turn-on, the full turn-on time of the safety switch can be effectively delayed, thereby suppressing the rapid increase of the drain current of the safety switch, preventing the triggering of reverse overcurrent faults, and avoiding interruption of the inner capacitor C. in The charging process is also straightforward. Furthermore, controlling the safety switch using this drive circuit is relatively simple, requiring no PWM wave transmission, eliminating concerns about drive delay or pulse length, and eliminating the risk of the safety switch S being damaged by high voltage due to high current shutdown. In addition, this invention enables rapid shutdown and rapid re-switching of the safety switch. Attached Figure Description

[0018] Figure 1 This is a schematic diagram showing the connection between a low-voltage battery and its safety switch. Figure 2 A circuit topology diagram of a specific embodiment of a driving circuit for a safety switch of a low-voltage battery provided by the present invention; Figure 3 This is a schematic diagram of a specific embodiment of a low-voltage battery power supply system provided by the present invention. Detailed Implementation

[0019] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0021] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0022] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0023] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0024] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0025] First, it should be noted that, as Figure 1 As shown, since the voltage of capacitor Cin inside safety switch S is zero when the DC / DC converter is first connected to the low-voltage battery, directly closing safety switch S is equivalent to turning capacitor Cin into a capacitor. in Directly connected to a low-voltage battery (current sampling Shunt resistor has a very small resistance value, on the order of mΩ), capacitor C inThe transient charging current can be very large. Excessive current sampling via the shunt resistor can trigger a reverse overcurrent fault in the DC / DC converter, thus stopping the charging of the internal capacitor C. in Charge.

[0026] Therefore, it is necessary to limit the flow of low-voltage battery energy to capacitor C. in The current. To address this, this application utilizes the drain current i in the linear operating region of the MOSFET. D With gate-source voltage V gs The proportional property is achieved by limiting V. gs The rise of the drain current i D The size of the capacitor C limits the flow of low-voltage battery energy to the capacitor C. in The current.

[0027] Example 1 Please see Figure 2 The driving circuit for a safety switch of a low-voltage battery shown includes: a driving module Driver and a first limiting resistor R. glimit1 Limiting capacitor C limit Second limiting resistor R glimit2 Adjusting resistor R g Accelerating resistor R speed Accelerating capacitor C speed Acceleration switch T speed and gate-source resistance R gs .

[0028] Specifically, the output terminal of the driver module is connected to the first limiting resistor R. glimit1 One end, and the accelerating resistor R speed One end is connected. The first limiting resistor R... glimit1 The other end is connected to the limiting capacitor C. limit One end, and the second limiting resistor R glimit2 One end is connected. And the accelerating resistor R... speed The other end is connected to the accelerating capacitor C speed One end is connected.

[0029] The reference terminal of the driver module is used to connect to the source of the safety switch, and the acceleration capacitor C... speed The other end, and the limiting capacitor R glimit1 The other end of each is connected to the reference end of the driver module.

[0030] Second limiting resistor R glimit2 The other end is connected to the regulating resistor R g One end is connected, while the adjusting resistor R g The other end is used to connect to the gate of the safety switch.

[0031] Gate-source resistance R gs It needs to be connected in parallel to the gate and source of the safety switch, with one end connected to the regulating resistor R. g One end is connected to the other end, which is connected to the reference end of the driver module.

[0032] Acceleration switch T speed It needs to be connected in parallel with the first limiting resistor R glimit1 Second limiting resistor R glimit2 Correspondingly, one end of it is connected to the first limiting resistor R. glimit1 One end is connected, and the other end is connected to the second limiting resistor R. glimit2 The other end is connected, and its control terminal is connected to the accelerating resistor R. speed and accelerating capacitor C speed Between. It should be noted that in this embodiment, a MOSFET, IGBT, or other field-effect transistors (voltage-driven switching transistors) can be used as the accelerating switch T. speed However, no restrictions are placed on this. Any modifications and refinements made by those skilled in the art to the embodiments of the present invention without departing from the spirit of the present invention still fall within the scope of the invention application patent.

[0033] Based on the specific circuit topology of the above-mentioned driving circuit, several voltage points are defined to facilitate the explanation of its operating principle, including: First limiting resistor R glimit1 Second limiting resistor R glimit2 The space between, or the connection point, is defined as V. int .

[0034] Second limiting resistor R glimit2 and adjusting resistor R g The space between, or the connection point, is defined as V. ext .

[0035] In addition, for the first limiting resistor R set glimit1 Second limiting resistor R glimit2 Limiting capacitor C limit Accelerating resistor R speed Accelerating capacitor C speed Larger parameters can be selected, i.e., devices with larger resistance or capacitance values. In response, when the safety switch needs to be activated for the first time, the driver module outputs a high-level signal V. CC (Drive electrical signal), due to the first limiting resistor R glimit1 Second limiting resistor R glimit2 The resistance value is set relatively large, and the limiting capacitor C is limited. limitMuch larger than the input capacitance of the safety switch (the equivalent capacitance formed between the gate and source, and between the gate and drain), i.e., the first limiting resistor R. glimit1 Second limiting resistor R glimit2 This will limit the amount of current flowing to the gate of the safety switch, and also limit the capacitance C. limit The magnitude of the charging current limits the capacitance C. limit Clamping safety switch gate-source voltage V gs Therefore, the high-level signal V output by the driver module is... CC It takes a long time to first apply the limiting capacitor C. limit Charging, corresponding V int The voltage rises very slowly, causing the safety switch gate-source voltage V to... gs The rise is also very slow, which extends the linear operating region of the safety switch, i.e., delays the full turn-on time of the safety switch, and can effectively suppress the gate current i of the safety switch. D The rapid increase.

[0036] It's important to note that safety switches typically use MOSFETs, which go through a linear operating region during the process of turning from cutoff to full turn-on. Within this region, the MOSFET acts as a variable resistor controlled by the gate-source voltage, with the drain current changing approximately linearly with the drain-source voltage. Therefore, by controlling the rise rate of the MOSFET's gate-source voltage, the MOSFET can operate in this variable-resistance state for a longer period, thus extending the linear operating region instead of rapidly entering saturation. This delays the full turn-on time, allowing the drain current to gradually increase.

[0037] In addition, for the limiting capacitor C limit The capacitance of the safety switch input capacitor needs to be at least greater than the preset first multiplier, so that its capacitance is much larger than the input capacitance of the safety switch. Similarly, for the first limiting resistor R... glimit1 The resistance value needs to exceed at least a preset first threshold and a second limiting resistor R. glimit2 The resistance value needs to exceed the preset second threshold and must meet the first limiting resistor R. glimit1 Second limiting resistor R glimit2 The resistance value is at least greater than the preset second-rate adjustment resistor R. g The resistance value.

[0038] Furthermore, regarding the accelerating resistor R speed and accelerating capacitor C speed It requires at least the product of its capacitance and resistance, i.e., R. speed *C speed It must be greater than R glimit1 *C limit This is how the accelerating capacitor C can be activated. speedLimiting capacitor C limit The voltage will only reach V after it is fully charged, or even after the safety switch is fully turned on. CC That is, it is necessary to accelerate capacitor C. speed The voltage needs to reach the high-level signal V output by the driver module after the safety switch is fully turned on. CC The size of the resistor. Furthermore, due to the output of the driver module and the first limiting resistor R... glimit1 Second limiting resistor R glimit2 Adjusting resistor R g Gate-source resistance R gs A closed loop is formed between them, V ext The voltage must be lower than V CC .

[0039] It should also be noted that, in this embodiment, the acceleration switch T... speed Taking a MOSFET as an example, and its drain is connected to the first limiting resistor R glimit1 One end is connected, and the source is connected to the second limiting resistor R. glimit2 The other end is connected, and the gate is connected to the accelerating resistor R. speed and accelerating capacitor C speed between.

[0040] Correspondingly, when the accelerating capacitor C speed The voltage on reaches V CC Then, at this time, the acceleration switch T speed Gate-source voltage V gs_Tspeed It is positive and can drive the acceleration switch T. speed Activate. And, at the acceleration switch T... speed After activation, the first limiting resistor R glimit1 Second limiting resistor R glimit2 When short-circuited, the gate resistance of the safety switch is only the regulating resistance R. g Furthermore, due to R speed *C speed The setting is relatively large, accelerating capacitor C speed It will maintain a slow discharge, i.e., accelerate the switch T. speed The safety switch can be delayed for a certain period of time before shutting off. If the safety switch shuts off during this period and needs to be turned on again, it can be activated via the accelerator switch T. speed This enables rapid secondary activation. This can be understood as follows: when the safety switch is initially activated, it will affect capacitor C. in Charging, and capacitor C in Discharge also requires a certain amount of time; therefore, a short-term re-activation of the safety switch will not cause capacitor C to fail. in This generates a large transient current, thus eliminating the need to suppress the drain current of the safety switch as required during initial switching. DOf course, if the time interval between the second activation is long, i.e., the accelerating capacitor C... speed The voltage has been too low due to prolonged discharge, making it unable to drive the acceleration switch T. speed The circuit is turned on again. At this point, the second activation of the safety switch is equivalent to the initial activation, thus fully protecting capacitor C. in Reliable operation.

[0041] In addition, when it is necessary to turn off the safety switch, the driver module outputs a low-level signal, and the gate charge of the safety switch can be adjusted by regulating the resistor R. g Acceleration switch T speed The body diode and the internal circuitry of the driver module are quickly grounded (the driver module output is connected to its internal grounding circuit) to achieve rapid shutdown of the safety switch. This can be understood as being achieved by adjusting the resistor R. g The resistance value, i.e. the rate at which the charge is released, is used to adjust the closing speed of the safety switch.

[0042] It should be noted that the design of the safety switch, whether it is an NMOS transistor or a PMOS transistor, remains basically the same and there is no difference. There is no restriction on this. Modifications and refinements made by those skilled in the art to the embodiments of the present invention without departing from the spirit of the present invention still fall within the scope of the invention application patent.

[0043] Example 2 Please see Figure 3 As shown, this embodiment also provides a low-voltage battery power supply system, including the drive circuit 10 described in Embodiment 1, a low-voltage battery 20, a safety switch 30, and a DC / DC converter 40. A capacitor, namely capacitor C, is connected in parallel to the input / output terminals of the DC / DC converter 40. in The positive terminal of the low-voltage battery 20 is connected to the drain of the safety switch 30, and the negative terminal is connected to the capacitor C. in The other end is connected, while the source of safety switch 30 is connected to capacitor C. in One end is connected, and the gate is connected to the driving circuit 10. The specific connection method can be found in Embodiment 1.

[0044] In addition, a current sampling resistor, namely a current sampling Shunt resistor, is connected in series on one side of the safety switch 30 to detect the magnitude of the current flowing through the safety switch 30. No further restrictions are imposed on this. Modifications and refinements made by those skilled in the art to the embodiments of the present invention without departing from the spirit of the present invention still fall within the scope of the invention application patent of the present invention.

[0045] Example 3 This embodiment also provides a vehicle power system, including at least the low-voltage battery power supply system described in Embodiment 2.

[0046] In summary, this invention provides a driving circuit for a safety switch of a low-voltage battery. By extending the linear operating region of the safety switch during its initial turn-on, the full turn-on time of the safety switch can be effectively delayed, thereby suppressing the rapid increase of the drain current of the safety switch, preventing the triggering of reverse overcurrent faults, and avoiding interruption of the inner capacitor C. in The charging process is also straightforward. Furthermore, controlling the safety switch using this drive circuit is relatively simple, requiring no PWM wave transmission, eliminating concerns about drive delay or pulse length, and eliminating the risk of the safety switch S being damaged by high voltage due to high current shutdown. In addition, this invention enables rapid shutdown and rapid re-switching of the safety switch.

[0047] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0048] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above description of the embodiments shown in this invention (including the content set forth in the abstract of the specification) is not intended to be an exhaustive enumeration or to limit the invention to the precise forms disclosed herein. Although specific embodiments and examples of the invention have been described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the invention, as will be recognized and understood by those skilled in the art. As indicated, these modifications can be made to the invention in accordance with the above description of the embodiments described herein, and such modifications will be within the spirit and scope of the invention.

[0051] This document has generally described the systems and methods in detail to aid in understanding the invention. Furthermore, various specific details have been set forth to provide a general understanding of embodiments of the invention. However, those skilled in the art will recognize that embodiments of the invention can be practiced without one or more specific details, or using other means, systems, accessories, methods, components, materials, parts, etc. In other instances, well-known structures, materials, and / or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention.

[0052] Therefore, although the invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are also within the scope of the foregoing disclosure, and it should be understood that in some cases, certain features of the invention may be adopted without departing from the scope and spirit of the invention and without corresponding use of other features. Thus, many modifications can be made to adapt a particular environment or material to the essential scope and spirit of the invention. The invention is not intended to be limited to the specific terminology used in the following claims and / or the specific embodiments disclosed as the best mode for carrying out the invention, but the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Therefore, the scope of the invention will be defined only by the appended claims.

Claims

1. A driving circuit for a safety switch of a low-voltage battery, characterized in that, include: The driver module's reference terminal is used to connect to the source of the safety switch; The first limiting resistor has one end connected to the output terminal of the drive module and the other end used to connect to the gate of the safety switch; A limiting capacitor is connected at one end to the other end of the first limiting resistor and at the other end to the reference terminal of the driving module. Wherein, the resistance value of the first limiting resistor is at least greater than a preset first threshold, and the capacitance value of the limiting capacitor is at least greater than the capacitance value of the safety switch input capacitor by a preset first multiple, so as to delay the full opening time of the safety switch when the driving module outputs a driving electrical signal.

2. The driving circuit for the safety switch of the low-voltage battery according to claim 1, characterized in that, Also includes: The second limiting resistor has one end connected to the other end of the first limiting resistor and one end of the limiting capacitor, and the other end is used to connect to the gate of the safety switch. An accelerating resistor is connected at one end to the output terminal of the driving module and at one end of the first limiting resistor. An accelerating capacitor has one end connected to the other end of the accelerating resistor and the other end connected to the reference terminal of the driving module. An acceleration switch is connected in parallel with the first limiting resistor and the second limiting resistor, and the control terminal is connected between the acceleration resistor and the acceleration capacitor; Wherein, the resistance value of the second limiting resistor exceeds at least a preset second threshold; The product of the resistance of the accelerating resistor and the capacitance of the accelerating capacitor is at least greater than the product of the resistance of the first limiting resistor and the capacitance of the limiting capacitor, so that the voltage of the accelerating capacitor can reach the voltage of the driving electrical signal after the limiting capacitor is fully charged, and the accelerating switch is turned on.

3. The driving circuit for the safety switch of the low-voltage battery according to claim 2, characterized in that, The acceleration switch is a MOSFET, with its drain connected to one end of the first limiting resistor and its source connected to the other end of the second limiting resistor. Specifically, when the voltage of the accelerating capacitor reaches the voltage of the driving electrical signal, the voltage of the gate of the accelerating switch is higher than the voltage of the source, and the voltage difference between the gate and the source exceeds the turn-on threshold, so that the accelerating switch is turned on.

4. The driving circuit for the safety switch of the low-voltage battery according to claim 3, characterized in that, The acceleration switch is also equipped with a body diode; The gate of the safety switch can be quickly grounded from the internal circuit of the drive module through the body diode of the acceleration switch, so as to achieve rapid turn-off of the safety switch.

5. The driving circuit for the safety switch of the low-voltage battery according to claim 4, characterized in that, Also includes: An adjustable resistor is used, with one end connected to the other end of the second limiting resistor and the other end used to connect to the gate of the safety switch. The closing speed of the safety switch can be adjusted by changing the resistance value of the regulating resistor.

6. The driving circuit for the safety switch of the low-voltage battery according to claim 5, characterized in that, The resistance values ​​of the first limiting resistor and the second limiting resistor are at least greater than the resistance value of the adjusting resistor by a preset second multiple.

7. The driving circuit for the safety switch of the low-voltage battery according to claim 2, characterized in that, Once the acceleration switch is turned on, it can be quickly turned on after the safety switch is turned off within a preset time. The preset time is related to the discharge time of the accelerating capacitor.

8. The driving circuit for the safety switch of the low-voltage battery according to claim 1, characterized in that, Also includes: Gate-source resistors are used to connect between the gate and source of a safety switch.

9. A low-voltage battery power supply system, characterized in that, Includes the drive circuit for the safety switch as described in any one of claims 1 to 8, a low-voltage battery, a safety switch, and a DC / DC converter; A capacitor is connected in parallel to the input / output terminals of the DC / DC converter; The positive terminal of the low-voltage battery is connected to the drain of the safety switch, and the negative terminal is connected to the other end of the capacitor. The source of the safety switch is connected to one end of the capacitor, and the gate is connected to the driving circuit.

10. The low-voltage battery power supply system according to claim 9, characterized in that, Also includes: A current sampling resistor is connected in series on one side of the safety switch.

11. A vehicle powertrain system, characterized in that, The low-voltage battery power supply system includes any one of claims 9 to 10.

Images