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, a reference end of which is used for being connected with a source electrode of the safety switch and is grounded; one end of the driving 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 driving resistor, and the other end of the limiting capacitor is connected with the drain electrode of the safety switch or grounded; wherein the capacitance value of the limiting capacitor at least exceeds the capacitance value of a parasitic Miller capacitor of the safety switch with the preset first multiplying power, so that the grid current of the safety switch is limited, and the Miller plateau area of the safety switch is prolonged. The Miller platform area of the safety switch is prolonged, so that the drain current iD of the safety switch can charge the inner side capacitor in an approximate constant current mode, triggering of a reverse over-current fault is prevented, and charging of the inner side capacitor cannot be 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 pre-charge 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 extends the Miller plateau region of the safety switch S to increase its drain current i D It can supply the inner capacitor C with an approximately constant current. in Charging eliminates the problem of rapid increase in reverse current, prevents the triggering of reverse overcurrent faults, and does not interrupt the inner capacitor C. 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, a reference terminal for connecting to the source of the safety switch and grounded; a driving 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 driving resistor and the other end of which is connected to the drain of the safety switch or grounded; wherein the capacitance value of the limiting capacitor is at least greater than the capacitance value of the parasitic Miller capacitance of the safety switch by a preset first rate, so as to limit the gate current of the safety switch and extend the Miller plateau region of the safety switch.

[0007] According to a specific embodiment of the present invention, the resistance value of the driving resistor is calculated based on the voltage of the driving electrical signal output by the driving module, the Miller plateau voltage of the safety switch, the capacitance value of the limiting capacitor, and preset current and voltage output by the low-voltage battery through the safety switch.

[0008] According to a specific embodiment of the present invention, the device further includes: an accelerating resistor, one end of which is connected to the output terminal of the driving module and one end of the driving 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 driving resistor and has a control terminal connected between the accelerating resistor and the accelerating capacitor; wherein the product of the resistance value of the accelerating resistor and the capacitance value of the accelerating capacitor exceeds at least a preset threshold, so that the voltage of the accelerating capacitor can reach the voltage of the driving electrical signal output by the driving module after a preset first time, and the accelerating switch is turned on.

[0009] 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 driving resistor, and its source is connected to the other end of the driving resistor; wherein, when the voltage of the acceleration capacitor reaches the voltage of the driving signal output by the driving module, 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.

[0010] 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.

[0011] 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 driving 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.

[0012] According to a specific embodiment of the present invention, when the other end of the limiting capacitor is used to connect to the drain of the safety switch, it further includes: a limiting resistor; and the limiting capacitor is connected to the other end of the driving resistor through the limiting resistor; wherein, the resistance value of the limiting resistor is at least less than the resistance value of the driving resistor of a preset proportional coefficient, and at least greater than the resistance value of the adjusting resistor of a preset second multiplier.

[0013] According to a specific embodiment of the present invention, when the other end of the limiting capacitor is grounded, a diode is further included; and the positive terminal of the diode is connected to the other end of the driving resistor, the negative terminal is connected to one end of the limiting capacitor, and the other end of the limiting capacitor is grounded.

[0014] 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 second time period; wherein, the preset second time period is related to the discharge time of the acceleration capacitor.

[0015] 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.

[0016] 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, and the positive and negative terminals of the low-voltage battery are respectively connected to the two ends of the capacitor; the safety switch is connected in series on the positive or negative side of the low-voltage battery, and its gate is connected to the drive circuit.

[0017] 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.

[0018] A vehicle power system includes the low-voltage battery power supply system described above.

[0019] This invention provides a driving circuit for a safety switch of a low-voltage battery. By extending the Miller plateau region of the safety switch when it is first turned on, the current through the safety switch remains constant for a preset time, thereby controlling the internal capacitor C. in The constant current pre-charge eliminates the problem of rapid increase in reverse current, prevents the triggering of reverse overcurrent faults, and does not interrupt the inner capacitor C. in Charging.

[0020] Meanwhile, 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 being damaged by high voltage due to high current shutdown. Furthermore, this invention enables rapid shutdown and rapid re-switching of the safety switch. Attached Figure Description

[0021] 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 The circuit topology diagram is shown in another specific embodiment of the driving circuit for a safety switch of a low-voltage battery provided by the present invention. Figure 4 This is a schematic diagram of a specific embodiment of a low-voltage battery power supply system provided by the present invention; Figure 5 This is a schematic diagram of another specific embodiment of a low-voltage battery power supply system provided by the present invention. Detailed Implementation

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] First, it should be noted that, as Figure 1 As shown, due to the fact that the internal capacitor C of the safety switch S of the DC / DC converter is connected to the low-voltage battery for the first time... in When the voltage is zero, directly closing the safety switch S is equivalent to turning capacitor C... in Directly connected to a low-voltage battery (current sampling Shunt resistor has a very small resistance, on the order of mΩ), capacitor C in The 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.

[0029] 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.

[0030] Example 1 Please see Figure 2 The driving circuit for a safety switch of a low-voltage battery shown includes: a driver module and a driving resistor R. ginitial Limiting capacitor C gdadd Limiting resistor R gdadd Adjusting resistor R g Accelerating resistor R speed Accelerating capacitor C speed Acceleration switch T speed and gate-source resistance R gs .

[0031] Specifically, the output of the driver module is connected to the drive resistor R. ginitial One end, and the accelerating resistor R speed One end is connected. The driving resistor R... ginitial The other end is connected to the limiting resistor R. gdadd One end, and the adjusting resistor R g 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.

[0032] The reference terminal of the driver module is connected to the source of the safety switch and is grounded, and the accelerating capacitor C... speed The other end is connected to the reference end of the driver module.

[0033] Limiting resistor R gdadd The other end is connected to the limiting capacitor C gdadd One end is connected, while the limiting capacitor C gdadd The other end is used to connect to the drain of the safety switch.

[0034] Adjusting resistor R g The other end is used to connect to the gate of the safety switch.

[0035] 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.

[0036] Acceleration switch T speed It needs to be connected in parallel with the driving resistor R ginitial Above, one end of it is connected to the driving resistor R. ginitial One end is connected, and the other end is connected to the driving resistor R. ginitial 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.

[0037] Based on the specific circuit topology of the above-mentioned driving circuit, in order to facilitate the explanation of its operating principle, a voltage point is also defined, namely the driving resistor R. ginitial Limiting resistor R gdadd and adjusting resistor Rg The connection point is defined as V. int .

[0038] In addition, safety switches usually use MOSFETs. To facilitate the explanation of the working principle of the driving circuit, this embodiment takes an NMOS transistor as an example for the safety switch. When the safety switch is an NMOS transistor, it needs to be set on the negative side of the low-voltage battery, that is, the safety switch is connected in series on the negative side of the low-voltage battery.

[0039] Understandably, when the MOSFET turns on, after the gate voltage rises to the threshold voltage, the drain current begins to increase, and the drain-source voltage gradually decreases. At this time, the voltage across the Miller capacitance between the gate and drain also changes. Due to the presence of the Miller capacitance, a charging current flows to the Miller capacitance during the decrease in drain-source voltage. This current slows down the rise rate of the gate voltage, thus creating a plateau.

[0040] Therefore, in this embodiment, under capacitive load conditions, the gate-drain voltage V of the safety switch is controlled by the approximately constant gate current in the Miller plateau region when the safety switch is turned on. gd And make it decrease linearly, i.e., Miller capacitance C gd charging current i Cgd =C gd *dV gd / dt. Therefore, the drain-source voltage V of the safety switch ds It will decrease linearly, at which point the safety switch will supply power to capacitor C. in Charging current i C =C*dV ds Since / dt is approximately a constant, it is possible to achieve the inner capacitance C. in The constant current charging avoids the problem of rapid increase in reverse current and prevents the occurrence of reverse overcurrent faults.

[0041] To address this, a limiting capacitor C is connected in parallel between the gate and drain of the safety switch. gdadd This is equivalent to the Miller capacitance C parasitic on the safety switch. gd A capacitor is connected in parallel, which increases the equivalent Miller capacitance of the safety switch, thereby extending the Miller plateau time of the safety switch. This means that when the safety switch is in the Miller plateau region, the current flowing through it can be kept constant. By controlling the duration of the Miller plateau region, the resistance to the inner capacitor C can be maintained within a preset time. in Constant current charging.

[0042] Secondly, it can be determined based on the internal capacitance C. inThe capacity is set with a constant pre-charge current and pre-charge voltage, which correspond to the current and voltage output by the low-voltage battery through the safety switch. The internal capacitance C can be calculated according to Q=I*t=C*U. in The slope of the voltage change is dV / dt. Meanwhile, for the limiting capacitor C... gdadd The capacitance of the safety switch parasitic on the Miller capacitance needs to exceed the preset first-rate value, making it much larger than the safety switch's parasitic Miller capacitance. Therefore, the gate current I in the Miller plateau region of the safety switch can be calculated based on the above. gmiller =C gdadd *dV / dt.

[0043] Finally, based on the voltage magnitude of the electrical signal driven by the driver module to drive the safety switch, i.e., the high-level signal V... CC And the Miller plateau voltage V of the safety switch gmiller (Determined by the properties of the MOSFET selected for the safety switch), the driving resistance R is calculated. ginitial The resistance value, i.e., R ginitial =(V CC -V gmiller ) / I gmiller .

[0044] It's understandable that increasing the gate drive resistance of the safety switch prolongs the charging time of the equivalent Miller capacitance, thus slowing down the rise rate of the safety switch gate voltage and extending the Miller plateau region. However, the gate drive resistance cannot be set too high, otherwise it will lead to an excessively slow switching speed and increased switching losses. Therefore, by configuring a limiting capacitor C... gdadd and the calculated driving resistance R ginitial This can extend the Miller plateau region of the safety switch for a more ideal time, that is, maintain the connection to the inner capacitor C for a preset time. in The constant current charging will not affect the normal opening and closing of the safety switch.

[0045] When the safety switch is turned on for the first time, the driver module outputs a high-level signal V. CC (Drive electrical signal), due to the drive resistor R ginitial It will limit the gate current of the safety switch, and also need to consider the equivalent Miller capacitance of the safety switch, that is, the parasitic Miller capacitance of the safety switch and the limiting capacitance C. gdadd Charging effectively delays the Miller plateau region of the safety switch. At this time, because the safety switch is in the Miller plateau region, the gate voltage remains relatively stable, and the conductivity of the corresponding safety switch channel remains essentially unchanged. Its drain current also remains constant, thus achieving the desired effect on the internal capacitor C. in Constant current charging.

[0046] 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 To exceed the preset threshold (R) speed *C speed (large enough) so that the accelerating capacitor C speed Inner capacitor C in V will only be reached after the constant current pre-charge is completed. CC That is, it is necessary to accelerate capacitor C. speed The voltage on the capacitor needs to be within the inner capacitor C. in After the constant current pre-charging is completed (after the preset first time), the high-level signal V output by the driver module is reached. CC The size. Furthermore, due to the output of the driver module and the drive resistance R... ginitial Adjusting resistor R g Gate-source resistance R gs A closed loop is formed between them, V int The voltage must be lower than V CC .

[0047] It should also be noted that, in this embodiment, the acceleration switch T... speed Taking a MOSFET as an example, and its drain and drive resistor R ginitial One end is connected, and the source is connected to the drive resistor R. ginitial The other end is connected, and the gate is connected to the accelerating resistor R. speed and accelerating capacitor C speed between.

[0048] 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 driving resistor R ginitial 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 switch can be delayed for a certain period of time (preset second 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 Enables rapid reactivation.

[0049] What can be understood here is that when the safety switch is turned on for the first time, 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 for constant current pre-charging as required during the initial turn-on. Of course, if the time interval between the second turn-on 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.

[0050] 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.

[0051] Meanwhile, regarding the limiting resistor R gdadd This can prevent limiting capacitor C gdadd The resistance value of the safety switch that affects its ability to turn off must be greater than that of the drive resistor R. ginitial It's an order of magnitude smaller, and it's still better than the adjustable resistor ratio R. g At least one order of magnitude larger, i.e., the limiting resistor R gdadd The resistance value is at least less than the preset proportional coefficient of the drive resistor R. ginitial The resistance value, and an adjustment resistor R that is at least greater than the preset second-rate. g The resistance value.

[0052] Therefore, it can be seen that when an NMOS transistor is used in the safety switch, the internal capacitor C can be controlled. in For constant current pre-charging, similarly, when a PMOS transistor is used as the safety switch, it only needs to be placed on the positive side of the low-voltage battery. The working principle is basically the same as described above, and it can also achieve the same effect on the internal capacitor C. in Constant current pre-charging is not limited and can be freely adjusted according to the actual application scenario. 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.

[0053] In another specific embodiment, this embodiment also designs a modified circuit for the above-mentioned drive, such as... Figure 3 As shown, it includes: a driver module (Driver) and a driver resistor (R). ginitial Limiting capacitor C add Diode D add Adjusting resistor R g Accelerating resistor R speed Accelerating capacitor C speed Acceleration switch T speed and gate-source resistance R gs .

[0054] It should be noted that this modified circuit can be used when the safety switch is located on the positive terminal side of the low-voltage battery. The output terminal of the corresponding driver module is connected to the drive resistor R. ginitial One end, and the accelerating resistor R speed One end is connected. The driving resistor R... ginitial The other end is connected to diode D respectively add The positive terminal, and the adjusting resistor R g 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. 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 is connected to the reference terminal of the driver module. Diode D add The negative terminal and the limiting capacitor C add One end is connected, while the limiting capacitor C add The other end is grounded. Adjust the resistor R. g The other end is used to connect to the gate of the safety switch, with a 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 reference terminal of the driver module, and the other end is connected to the accelerator switch T. speed Parallel to the driving resistor R ginitial Above, one end of it is connected to the driving resistor R. ginitial One end is connected, and the other end is connected to the driving resistor R. ginitial The other end is connected, and its control terminal is connected to the accelerating resistor R. speed and accelerating capacitor C speed between.

[0055] In this regard, although the capacitance C is limited add Instead of increasing the equivalent Miller capacitance of the safety switch, it can still divert the gate current of the safety switch for charging, thereby extending the Miller plateau region of the safety switch, and for the drive resistor R ginitialThe resistance value can still be configured in the above manner, and it can still achieve the function of controlling the inner capacitor C. in The constant current pre-charge will not be discussed in detail here. As for diode D... add It can effectively prevent the limiting capacitor C add Reverse discharge.

[0056] Example 2 Please see Figure 4 , 5 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. The drive circuit can be configured as follows: Figure 2 The circuit design shown can also be implemented using, for example... Figure 3 The circuit design shown, and when using, as Figure 2 In the circuit design shown, the safety switch 30 can be placed on either the positive or negative side of the low-voltage battery. When using... Figure 3 In the circuit design shown, the safety switch 30 needs to be placed on the positive terminal side of the low-voltage battery. A capacitor, C, is connected in parallel across the input / output terminals of the DC / DC converter 40. in Its two ends can be normally connected to the positive and negative terminals of the low-voltage battery 20, respectively.

[0057] 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.

[0058] Example 3 This embodiment also provides a vehicle power system, including at least the low-voltage battery power supply system described in Embodiment 2.

[0059] In summary, this invention provides a driving circuit for a safety switch of a low-voltage battery. By extending the Miller plateau region of the safety switch when it is first turned on, the magnitude of the current through the safety switch remains constant for a preset time, thereby controlling the internal capacitor C. in The constant current pre-charge eliminates the problem of rapid increase in reverse current, prevents the triggering of reverse overcurrent faults, and does not interrupt the inner capacitor C. in Charging.

[0060] Meanwhile, 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 being damaged by high voltage due to high current shutdown. Furthermore, this invention enables rapid shutdown and rapid re-switching of the safety switch.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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 and is grounded. The driving resistor has one end connected to the output terminal of the driving module and the other end used to connect to the gate of the safety switch. The limiting capacitor has one end connected to the other end of the driving resistor, and the other end is used to connect to the drain of the safety switch or to ground. The capacitance of the limiting capacitor is at least greater than the capacitance of the Miller capacitance parasitic on the safety switch by a preset first multiple, so as to limit the gate current of the safety switch and extend the Miller plateau region of the safety switch.

2. The driving circuit for the safety switch of the low-voltage battery according to claim 1, characterized in that, The resistance value of the drive resistor is calculated based on the voltage of the drive signal output by the drive module, the Miller plateau voltage of the safety switch, the capacitance value of the limiting capacitor, and the preset current and voltage output by the low-voltage battery through the safety switch.

3. The driving circuit for the safety switch of the low-voltage battery according to claim 1, characterized in that, Also includes: An accelerating resistor, one end of which is connected to the output terminal of the driving module and one end of the driving 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 driving resistor, and the control terminal is connected between the acceleration resistor and the acceleration capacitor. Wherein, the product of the resistance value of the accelerating resistor and the capacitance value of the accelerating capacitor exceeds at least a preset threshold, so that the voltage of the accelerating capacitor can reach the voltage of the driving electrical signal output by the driving module after a preset first time, and turn on the accelerating switch.

4. The driving circuit for the safety switch of the low-voltage battery according to claim 3, characterized in that, The acceleration switch is a MOSFET, with its drain connected to one end of the driving resistor and its source connected to the other end of the driving resistor. Specifically, when the voltage of the accelerating capacitor reaches the voltage of the driving signal output by the driving module, 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.

5. The driving circuit for the safety switch of the low-voltage battery according to claim 4, 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.

6. The driving circuit for the safety switch of the low-voltage battery according to claim 5, characterized in that, Also includes: An adjustable resistor is provided, with one end connected to the other end of the driving 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.

7. The driving circuit for the safety switch of the low-voltage battery according to claim 6, characterized in that, When the other end of the limiting capacitor is used to connect to the drain of the safety switch, it also includes: a limiting resistor; Furthermore, the limiting capacitor is connected to the other end of the driving resistor through the limiting resistor; Wherein, the resistance value of the limiting resistor is at least less than the resistance value of the driving resistor of the preset proportional coefficient, and at least greater than the resistance value of the adjusting resistor of the preset second multiplier.

8. The driving circuit for the safety switch of the low-voltage battery according to claim 6, characterized in that, When the other end of the limiting capacitor is grounded, a diode is also included; Furthermore, the positive terminal of the diode is connected to the other end of the driving resistor, and the negative terminal is connected to one end of the limiting capacitor, with the other end of the limiting capacitor grounded.

9. The driving circuit for the safety switch of the low-voltage battery according to claim 3, 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 second time. The preset second time is related to the discharge time of the accelerating capacitor.

10. 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.

11. 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 10, 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, and the positive and negative terminals of the low-voltage battery are respectively connected to the two ends of the capacitor. The safety switch is connected in series on the positive or negative side of the low-voltage battery, and its gate is connected to the drive circuit.

12. The low-voltage battery power supply system according to claim 11, characterized in that, Also includes: A current sampling resistor is connected between the low-voltage battery and the capacitor.

13. A vehicle powertrain system, characterized in that, The low-voltage battery power supply system includes any one of claims 11 to 12.

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