Overvoltage protection circuit, vehicle equipment power supply control device and moving tool

Abstract

The utility model discloses an overvoltage protection circuit, and the circuit comprises a switch control module which comprises a switch control device connected with a control end of a switch device, and the switch device controls the on or off of the switch device through the on or off of the switch control device; the first overvoltage protection module is connected with the control end of the switch control device and the power supply, and when the working voltage of the power supply connected with the switch control device exceeds a first overvoltage threshold value limited by the first overvoltage protection module, the first overvoltage protection module is configured to enable the switch control device to be closed; and the second overvoltage protection module is connected with the power supply and the control end of the switching device, and when the working voltage of the power supply exceeds a second overvoltage threshold limited by the second overvoltage protection module, the second overvoltage protection module is configured to turn off the switching device. The utility model further provides a corresponding vehicle equipment power supply control device and a moving tool. According to the circuit, a redundancy protection mechanism is added, and the possibility of circuit overvoltage protection failure is reduced.

Description

Technical Field

[0001] The utility model relates to the field of circuits, in particular to a switch circuit based on a MOS tube. Background Art

[0002] In the electrical field, DC power supply equipment or load equipment generally needs to have overvoltage protection function. The underlying drive controller products of intelligent driving will be interconnected with many peripherals, such as IMU (Inertial Measurement Unit) modules, sound and light warning devices, laser radars, wheel speed meter modules, battery charging control, etc. When powering circuit modules and peripherals, it is necessary not only to control the power on and off of the circuit, but also to consider the power consumption requirements of the load at the moment of startup. It is also necessary to consider that the drive circuit should be able to be cut off immediately in the event of a short circuit to protect the circuit from dangers such as overcurrent breakdown, overvoltage damage, and overtemperature fire.

[0003] At present, the overvoltage protection function is basically realized by using TVS (Transient Voltage Suppressor, also known as transient voltage suppression diode) to protect the circuit, or directly using the on-resistance of the MOS tube as the short-circuit current collection setting, using the turn-on voltage of the transistor as the threshold of the current collection to achieve short-circuit protection, or by adding an overvoltage protection circuit such as a voltage regulator diode to achieve the protection function.

[0004] The existing technical solutions currently have at least the following defects:

[0005] 1. The protection circuit is always effectively turned on, and there is no control strategy for the subsequent power supply, which is difficult to implement, especially when the static power consumption requirement is high.

[0006] 2. After an overvoltage occurs, the circuit can only be protected by the hardware itself and the subsequent circuits. Especially when the voltage fluctuates near the overvoltage threshold, frequent switching of the MOS tube may damage the MOS and cause it to burn out.

[0007] 3. When the key components in the overvoltage protection circuit fail, the overvoltage protection function will fail, which can easily cause damage to the subsequent load.

[0008] In view of this, it is urgent to find a stable and reliable overvoltage protection circuit with overvoltage failure protection function. Utility Model Content

[0009] In order to solve at least one problem existing in the above-mentioned prior art, the utility model provides an overvoltage protection circuit on one hand, which is used to protect at least a switching device and a subsequent load connected to the output end of the switching device, and the circuit includes:

[0010] The switch control module includes a switch control device connected to the control end of the switch device, and the switch device is turned on or off by turning on or off the switch control device.

[0011] A first overvoltage protection module connected to the control terminal of the switch control device and the power supply, wherein when the operating voltage of the power supply connected to the switch device exceeds a first overvoltage threshold defined by the first overvoltage protection module, the first overvoltage protection module is configured to shut down the switch control device;

[0012] A second overvoltage protection module is connected to the power supply and the control end of the switch device, wherein when the operating voltage of the power supply exceeds a second overvoltage threshold defined by the second overvoltage protection module, the second overvoltage protection module is configured to turn off the switch device.

[0013] In some embodiments of the present invention, the switch control module is further connected to a signal input terminal for receiving a control signal, and the switch control device is turned on or off according to a high level or a low level state of the control signal.

[0014] This implementation can use both hardware and software to comprehensively protect the switch device to be protected or the subsequent load of the circuit. When the hardware protection mechanism fails, the circuit can continue to be protected by software, that is, when an abnormality is found, the control signal received at the input end is converted to a low level, so that the switch control device can be turned off, so that the protected switch device is turned off, forming another redundant protection mechanism, thereby achieving the purpose of maximizing the protection of the switch device and the subsequent load.

[0015] Furthermore, in some embodiments of the present invention, the overvoltage protection circuit also includes a signal diagnosis module having one end connected to the output end of the switching device and the other end grounded, for collecting the output voltage of the switching device and controlling the control signal received by the signal input end to be a low level when the output voltage is abnormal.

[0016] In this implementation, the signal diagnosis module is used to monitor the switch device, so that the process of discovering abnormal voltage on the switch device and adjusting the input signal accordingly can be automated, thereby reducing labor costs and saving time and effort.

[0017] Preferably, in some embodiments of the present invention, the first overvoltage threshold does not exceed the second overvoltage threshold.

[0018] Such an implementation ensures that the secondary overvoltage protection part used to supplement or rescue the primary overvoltage protection will not control the switch device to be turned off before the primary overvoltage protection part.

[0019] Furthermore, in some embodiments of the present invention, the first overvoltage protection module includes a first overvoltage threshold limiting device that limits the first overvoltage threshold and a first switch protection device, the first overvoltage threshold limiting device is connected to the control end of the first switch protection device, and the first switch protection device is connected to the control end of the switch control device, so that the switch control device is controlled to be turned off by the first switch protection device according to the overvoltage state of the first overvoltage threshold limiting device.

[0020] In some embodiments of the present invention, the second overvoltage protection module includes a second overvoltage threshold limiting device that limits the second overvoltage threshold, a second switch protection device, and a third switch protection device. One end of the second overvoltage threshold limiting device is connected to a power supply, and the other end is connected to a control end of the second switch protection device. The second switch protection device is connected to the control end of the third switch protection device, and the third switch protection device is connected to the control end of the switch device, so that the switch device is controlled to be shut down by the second switch protection device and the third switch protection device according to the overvoltage state of the second overvoltage threshold limiting device.

[0021] Furthermore, in some embodiments of the present invention, the switch control module further includes a first voltage divider circuit and a second voltage divider circuit, and the switch control device is turned on by the first voltage divider circuit and controls the switch device to be turned on or off by the second voltage divider circuit.

[0022] Optionally or in combination, the first overvoltage protection module further includes a third voltage divider circuit, wherein the first switch protection device in the first overvoltage protection module is turned on through the third voltage divider circuit.

[0023] Optionally or in combination, the second overvoltage protection module further includes a fourth voltage divider circuit, the second switch protection device in the second overvoltage protection module is turned on by the fourth voltage divider circuit, and the turn-off of the switch device is controlled by the turn-on of the third switch protection device.

[0024] Furthermore, in some embodiments of the present invention, the first voltage dividing circuit may include a first series resistor having one end connected to the signal input end and the other end connected to the ground, wherein the connection end of the two resistors in the first series resistor is connected to the control end of the switch control device; the second voltage dividing circuit may include a second series resistor having one end connected to the power supply and the other end connected to the switch control device, wherein the connection end of the two resistors in the second series resistor is connected to the control end of the switch device.

[0025] Optionally or in combination, the third voltage divider circuit may include a third series resistor having one end connected to the first switch protection device and the other end grounded, wherein the connection end of the two resistors in the third series resistor is connected to the first overvoltage threshold limiting device, and the other end of the first overvoltage threshold limiting device is connected to the power supply.

[0026] Optionally or in combination, the fourth voltage-dividing circuit may include a fourth series resistor with one end being grounded and the other end being connected to the control end of the second switch protection device, wherein the connection ends of the two resistors in the fourth series resistor are connected to the second overvoltage threshold limiting device, and the other end of the second overvoltage threshold limiting device is connected to the power supply.

[0027] Optionally, in some embodiments of the present invention, the signal diagnosis module may further include a fifth voltage-dividing circuit, the fifth voltage-dividing circuit including a fifth series resistor having one end connected to the output end of the switching device and the other end grounded, wherein the connection end of the two resistors in the fifth series resistor is the collection end of the output voltage of the switching device.

[0028] Additionally, in some embodiments of the present invention, the circuit may further include a protection device having one end connected to the control end of the switch device and the other end connected to the power supply.

[0029] Through the protection device, the stable voltage required by the switching device can be maintained to prevent the switching device from being broken down.

[0030] Preferably, in some embodiments of the present invention, the switch device is a PMOS field effect transistor.

[0031] The switch control device, the first switch protection device, the second switch protection device and the third switch protection device are selected from triodes or field effect transistors.

[0032] The protection device, the first overvoltage threshold limiting device and the second overvoltage threshold limiting device are zener diodes.

[0033] Among them, the use of PMOS tubes as switch devices can save the additional and more complicated boost circuit required by the existing circuit structure where the switch devices are NMOS tubes, thereby reducing manufacturing costs and system power consumption.

[0034] Specifically, in some embodiments of the present invention, the switch control device, the first switch protection device, and the second switch protection device are NPN transistors, and the third switch protection device is a PNP transistor.

[0035] In this case, the source of the switching device is connected to the power supply, the gate is connected to the connection end of the two resistors of the second series resistor in the second voltage divider circuit, and the drain is connected to the subsequent load; the base of the switch control device is connected to the connection end of the two resistors of the first series resistor in the first voltage divider circuit and the collector of the first switch protection device, the collector is connected to the gate of the switching device through a resistor in the second voltage divider circuit, and the emitter is grounded; the emitter of the first switch protection device is grounded, the base is connected to the third voltage divider circuit (third series resistor), and is connected to the first through a resistor in the third voltage divider circuit (third series resistor). The positive pole of the overvoltage threshold limiting device is connected, and the negative pole of the first overvoltage threshold limiting device is connected to the power supply; the emitter of the second switch protection device is grounded, the base is connected to the fourth voltage divider circuit (fourth series resistor), and is connected to the positive pole of the second overvoltage threshold limiting device through a resistor in the fourth voltage divider circuit (fourth series resistor), the collector is connected to the base of the third switch protection device through a resistor, and the negative pole of the second overvoltage threshold limiting device is connected to the power supply; the emitter of the third switch protection device is connected to the power supply, the collector is connected to the gate of the switch device and the positive pole of the protection device, and the negative pole of the protection device is connected to the power supply.

[0036] In a second aspect, the utility model further provides a vehicle equipment power supply control device, comprising the overvoltage protection circuit provided in any of the above embodiments.

[0037] In a third aspect, the utility model further provides a mobile tool, comprising the vehicle equipment power supply control device provided in any of the above embodiments.

[0038] The overvoltage protection circuit provided by the utility model not only ensures that the overvoltage protection function in the circuit can be normally implemented, but also adds a redundant protection mechanism. When the voltage far exceeds the limit that the first overvoltage protection module can withstand or some circuit components are damaged, resulting in the failure of the overvoltage protection, the overvoltage protection of the switch device and its subsequent load can be continued through another second overvoltage protection module to compensate for the failed overvoltage protection of the previous stage, forming a double insurance, thereby greatly reducing the possibility of failure of the circuit overvoltage protection, protecting the switch device and its subsequent load as much as possible, reducing the risk of circuit failure, improving system safety, and making the circuit have a wider range of applications.

[0039] Among them, the first overvoltage protection module realizes the overvoltage protection function by disabling the control device of the control switch device, and the second overvoltage protection module realizes this function by directly disabling the switch device itself, which also prevents the occurrence of overvoltage failure caused by damage or failure of the control device used to control the on and off of the switch device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1A schematic structural diagram of an overvoltage protection circuit provided in one embodiment of the utility model is shown.

[0041] Figure 2 A schematic diagram of the structure of each module in an overvoltage protection circuit provided in one embodiment of the utility model is shown.

[0042] Figure 3 A circuit diagram of an overvoltage protection circuit provided in one embodiment of the utility model is shown. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the utility model can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to facilitate a more thorough understanding of the utility model and to fully convey the concept of the utility model to those skilled in the art.

[0044] The utility model provides a mobile tool, which may be a vehicle or a robot having the following functions:

[0045] (1) Passenger-carrying function, such as family cars and buses;

[0046] (2) Cargo-carrying functions, such as ordinary trucks, van trucks, trailer trucks, closed trucks, tank trucks, flatbed trucks, container trucks, dump trucks, trucks with special structures, etc.;

[0047] (3) Tool functions, such as logistics delivery vehicles, automatic guided transport vehicles, patrol vehicles, cranes, hoists, excavators, bulldozers, forklifts, rollers, loaders, off-road engineering vehicles, armored engineering vehicles, sewage treatment vehicles, sanitation vehicles, vacuum trucks, floor washing vehicles, sprinkler trucks, sweeping robots, food delivery robots, shopping guide robots, welcoming robots, disinfection robots, lawn mowers, golf carts, etc.;

[0048] (4) Entertainment functions, such as entertainment vehicles, amusement park self-driving devices, balance vehicles, etc.;

[0049] (5) Special rescue functions, such as fire trucks, ambulances, power repair vehicles, engineering rescue vehicles, etc.

[0050] Vehicles or robots with the above functions include but are not limited to vehicles or robot equipment with L0-L5 autonomous driving technology levels as established by the Society of Automotive Engineers International (SAE International) or the Chinese national standard "Automotive Driving Automation Classification".

[0051] The mobile tool provided by the utility model can be provided with an autonomous driving domain controller and various sensors for sensing environmental information and the mobile tool's own information (including but not limited to lidar, camera, millimeter wave radar, ultrasonic radar, inertial measurement unit, wheel speed meter, etc.), wherein the autonomous driving domain controller is communicatively connected with the various sensors, and a path is planned for the mobile tool based on the environmental information and the mobile tool's own information collected by these sensors, so as to achieve the purpose of controlling the mobile tool to drive automatically.

[0052] The utility model also provides a vehicle equipment power supply control device, comprising: an overvoltage protection circuit in any of the following embodiments of the present application. In the above mobile tool, the automatic driving domain controller and the above various sensors are in communication connection with the vehicle equipment power supply control device provided by the utility model.

[0053] refer to Figure 1 , shows a schematic diagram of the structure of an overvoltage protection circuit provided by an embodiment of the utility model. Figure 1 As shown, the overvoltage protection circuit 1 provided by the present invention mainly includes a switch device 10 , a switch control module 20 , a first overvoltage protection module 30 and a second overvoltage protection module 40 .

[0054] The switch device 10 is connected to a power supply, and the output end of the switch device 10 is connected to a subsequent load. The subsequent load may be an external device, module or circuit, etc., which will not be elaborated in detail in the present invention.

[0055] The switch control module 20 includes a switch control device 201 , and the switch control device 201 is connected to the control end of the switch device 10 .

[0056] The first overvoltage protection module 30 is connected to the power supply and the control terminal of the switch control device 201 .

[0057] The second overvoltage protection module 40 is connected to the power supply and the control terminal of the switch device 10 .

[0058] The working state of the switch device 10 is controlled by controlling the working state of the switch control module 20. That is, the switch device 10 is turned on or off by controlling the switch control device 201 to turn on or off. When the working voltage of the power supply exceeds the first overvoltage threshold defined by the first overvoltage protection module 30, the first overvoltage protection module 30 is configured to turn off the switch control device 201; when the working voltage of the power supply exceeds the second overvoltage threshold defined by the second overvoltage protection module 40, the second overvoltage protection module is configured to turn off the switch device 10.

[0059] Therefore, when the overvoltage protection circuit is in normal working state and overvoltage occurs, the first overvoltage protection module will control the switch control device to shut down, causing the protected switch device to shut down, and the switch device will not be damaged after shutting down. When the switch control device fails to control the switch device to shut down during overvoltage in time due to various reasons (for example, the voltage borne by the first overvoltage protection module is too high and exceeds its tolerance range or a component in the circuit fails, etc.), the second overvoltage protection module directly connected to the control end of the switch device can shut down the switch device to achieve the purpose of protecting the switch device and the subsequent load. Therefore, the second overvoltage protection module expands the coverage of the first overvoltage protection, and together with the first overvoltage protection module, forms a redundant protection mechanism for the circuit, greatly reducing the risk of overvoltage protection failure.

[0060] The switch control module in the above circuit can also be connected to a signal input terminal for receiving a control signal, and the switch control device therein can be turned on or off according to the high level or low level state of the control signal.

[0061] The advantage of such a setting is that it can use both hardware and software to comprehensively protect the switch device to be protected or the subsequent load of the circuit. When the hardware protection mechanism fails, the circuit can continue to be protected by software, that is, when an abnormality is found, the control signal received at the input end is converted to a low level, so that the switch control device can be turned off, so that the protected switch device is turned off, thereby achieving the purpose of protecting the switch device and the subsequent load.

[0062] like Figure 1 As shown, the circuit may also include a signal diagnosis module 50 having one end connected to the output end of the switching device and the other end grounded, for collecting the output voltage of the switching device and controlling the control signal received at the signal input end to change from a high level to a low level state when the output voltage is abnormal.

[0063] Those skilled in the art can understand that, since the second overvoltage protection module is a supplementary protection and rescue measure for the first overvoltage protection module, the second overvoltage threshold defined by the second overvoltage protection module will not be less than the first overvoltage threshold defined by the first overvoltage protection module. This ensures that the secondary overvoltage protection part will not control the switch device to shut down before the primary overvoltage protection part.

[0064] refer to Figure 2 , shows a schematic diagram of the structure of each module in the overvoltage protection circuit provided in one embodiment of the utility model.

[0065] Exemplarily, the first overvoltage protection module 30 includes a first overvoltage threshold limiting device 301 that limits a first overvoltage threshold and a first switch protection device 302, the first overvoltage threshold limiting device 301 is connected to the control end of the first switch protection device 302, and the first switch protection device 302 is connected to the control end of the switch control device 201, so that the switch control device 201 is controlled to be turned off by the first switch protection device 301 according to the overvoltage state of the first overvoltage threshold limiting device.

[0066] Exemplarily, the second overvoltage protection module includes a second overvoltage threshold limiting device 401 that limits the second overvoltage threshold, a second switch protection device 402, and a third switch protection device 403. One end of the second overvoltage threshold limiting device 401 is connected to the power supply, and the other end is connected to the control end of the second switch protection device 402. The second switch protection device 402 is connected to the control end of the third switch protection device 403, and the third switch protection device 403 is connected to the control end of the switch device 10, so that the switch device 10 is controlled to be turned off by the second switch protection device 402 and the third switch protection device 403 according to the overvoltage state of the second overvoltage threshold limiting device.

[0067] Exemplarily, the switch control module 20 may further include a first voltage divider circuit 202 and a second voltage divider circuit 203 . The switch control device 201 is turned on by the first voltage divider circuit 202 and controls the switch device 10 to be turned on or off by the second voltage divider circuit 203 .

[0068] Furthermore, the first overvoltage protection module 30 and the second overvoltage protection module 40 may also respectively turn off the switch control device 201 and the switch device 10 through corresponding voltage dividing circuits.

[0069] The first overvoltage protection module may include a third voltage divider circuit 303 , wherein the first switch protection device 302 in the first overvoltage protection module is turned on by the third voltage divider circuit 305 .

[0070] The second overvoltage protection module may include a fourth voltage divider circuit 404 , wherein the second switch protection device 402 in the second overvoltage protection module is turned on by the fourth voltage divider circuit 404 , and the turn-off of the switch device 10 is controlled by the turn-on of the third switch protection device 403 .

[0071] In the above embodiment, specifically, the first voltage divider circuit 202 may include a first series resistor having one end connected to the signal input end and the other end grounded, wherein the connection end of the two resistors in the first series resistor is connected to the control end of the switch control device 20; the second voltage divider circuit 203 includes a second series resistor having one end connected to the power supply and the other end connected to the switch control device 201, wherein the connection end of the two resistors in the second series resistor is connected to the control end of the switch device 10.

[0072] The third voltage divider circuit 303 may include a third series resistor having one end connected to the first switch protection device 302 and the other end grounded, wherein the connection end of the two resistors in the third series resistor is connected to the first overvoltage threshold limiting device 301, and the other end of the first overvoltage threshold limiting device 301 is connected to the power supply.

[0073] The fourth voltage divider circuit 404 includes a fourth series resistor with one end being grounded and the other end being connected to the control end of the second switch protection device 402, wherein the connection ends of the two resistors in the fourth series resistor are connected to the second overvoltage threshold limiting device 401, and the other end of the second overvoltage threshold limiting device 401 is connected to the power supply.

[0074] The specific circuit structure can be found in the following text. Figure 3 A circuit diagram provided by one embodiment of the utility model is shown.

[0075] Those skilled in the art can set the specific structures of the first voltage divider circuit 202, the second voltage divider circuit 203, the third voltage divider circuit 303 and the fourth voltage divider circuit 404 accordingly according to actual needs. Those skilled in the art should understand that the switch control module and the first and second overvoltage protection modules can also adopt other forms, as long as the switch device can stop working when the voltage exceeds the preset threshold, and the switch device will not shut down automatically when the voltage is within the tolerable range of the circuit. As for the control mode of the first switch protection device 302 on / off the switch control device 201 and the second and third switch protection devices 402 and 403 on / off the switch device 10, it depends on the type of the selected first, second and third switch protection devices and switch control devices (NMOS, PMOS, NPN, PNP, etc.). Those skilled in the art can select the corresponding appropriate device type and its output mode for the switch device according to actual needs and conditions, so as to select the control mode of the overvoltage protection module and / or the switch control module on the switch device in different voltage ranges. The following text will be explained with examples of specific device types.

[0076] Optionally, the signal diagnosis module 50 may further include 501, wherein the fifth voltage divider circuit 501 includes a fifth series resistor having one end connected to the output end of the switch device 10 and the other end grounded. The connection end of the two resistors in the fifth series resistor is set as a collection end for the output voltage of the switch device 10.

[0077] Those skilled in the art should understand that there are many ways to collect the output voltage of the switch device 10. The present invention only exemplarily adopts a relatively simple way, and the specific collection and monitoring means can be set accordingly according to the specific requirements in the actual application, and the present invention will not be described in detail here.

[0078] In some embodiments, the circuit may further include a protection device having one end connected to the control end of the switch device 10 and the other end connected to the power supply. The protection device may be, for example, a voltage stabilizing diode.

[0079] The voltage stabilizing diode can clamp the voltage of the switching device in the switch module, maintain the stable voltage required by the switching device, and prevent the switching device from being broken down, thereby avoiding unnecessary damage.

[0080] In some embodiments, the switch device 10 may be a PMOS field effect transistor, and the switch control device 201 , the first switch protection device 302 , the second switch protection device 402 , and the third switch protection device 403 may be selected from triodes or field effect transistors.

[0081] The first overvoltage threshold limiting device 301 and the second overvoltage threshold limiting device 401 are zener diodes.

[0082] Exemplarily, the switch control device 201 , the first switch protection device 302 , and the second switch protection device 402 are NPN transistors, and the third switch protection device 403 is a PNP transistor.

[0083] In this example, the source of the switch device 10 is connected to the power supply, the gate is connected to the connection end of the two resistors of the second series resistor in the second voltage divider circuit, and the drain is connected to the subsequent load;

[0084] The base of the switch control device 201 is connected to the connection end of the two resistors of the first series resistor in the first voltage divider circuit 202 and the collector of the first switch protection device 302, the collector is connected to the gate of the switch device 10 through a resistor in the second voltage divider circuit 203, and the emitter is grounded;

[0085] The emitter of the first switch protection device 302 is grounded, the base is connected to the third voltage divider circuit 303 (third series resistor), and is connected to the positive electrode of the first overvoltage threshold limiting device 301 through a resistor in the third voltage divider circuit 303 (third series resistor), and the negative electrode of the first overvoltage threshold limiting device 301 is connected to the power supply;

[0086] The emitter of the second switch protection device 402 is grounded, the base is connected to the fourth voltage divider circuit 404 (fourth series resistor), and is connected to the positive electrode of the second overvoltage threshold limiting device 401 through a resistor in the fourth voltage divider circuit 404 (fourth series resistor), the collector is connected to the base of the third switch protection device 403 through a resistor, and the negative electrode of the second overvoltage threshold limiting device 401 is connected to the power supply;

[0087] The emitter of the third switch protection device 401 is connected to the power supply, the collector is connected to the gate of the switch device 10 and the positive electrode of the protection device, and the negative electrode of the protection device is connected to the power supply.

[0088] Regarding the selection of each switch device in the circuit provided by the utility model, those skilled in the art can understand that the first, second, and third switch protection devices in the utility model can be triodes, or alternatively, MOS tubes. These switch devices can be switch devices of the same type, for example, all MOS tubes, or all triodes; alternatively, some of them can be MOS tubes and the other part can be triodes. Regardless of the type of switch device each switch device is, those skilled in the art can make corresponding adaptive deformations to the corresponding structures in the above circuits according to the working principles of the corresponding switch devices.

[0089] The advantage of configuring the switch device as a PMOS tube is that the additional and more complicated boost circuit required when the switch device is an NMOS tube in the existing circuit structure can be omitted, thereby reducing manufacturing costs and system power consumption.

[0090] The circuit provided by one embodiment of the present invention is specifically described below by taking the switching device 10 as a PMOS transistor Q1, the switch control device 201 as an NPN transistor Q2, the first switch protection device 302 as an NPN transistor Q3, the second switch protection device 402 as an NPN transistor Q4, and the third switch protection device 403 as a PNP transistor Q5 as an example.

[0091] refer to Figure 3 , which shows a specific implementation of the overvoltage protection circuit of the utility model.

[0092] In this circuit, the power supply is VBAT, and the output voltage of the switch device 10 is VB_PR. The switch device is Q1.

[0093] The switch control module includes a switch control device Q2 and a first voltage divider circuit composed of series resistors R3 and R8 and a second voltage divider circuit composed of series resistors R1 and R4.

[0094] The first overvoltage protection module includes a first overvoltage threshold limiting device D2, a first switch protection device Q3, and a third voltage dividing circuit composed of series resistors R5 and R7.

[0095] The second overvoltage protection module includes a second overvoltage threshold limiting device D3, a second switch protection device Q4, a third switch protection device Q5, and a fourth voltage dividing circuit composed of series resistors R9 and R10.

[0096] The diagnosis module includes a fifth voltage divider circuit composed of series resistors R2 and R6.

[0097] Still Figure 3 As shown, the overvoltage protection circuit also includes a voltage stabilizing diode D1.

[0098] The connection relationship and corresponding functions of each circuit component are described in detail below.

[0099] Figure 3 The circuit shown includes resistors R1-R11, transistors Q2 / Q3 / Q4 / Q5, voltage stabilizing diodes D1 / D2 / D3 and a PMOS transistor Q1.

[0100] The cathode of D2 is connected to the DC power supply VBAT, the cathode of D3, the emitter of Q5, one end of R1, the cathode of D1, and the source of Q1, and the anode is connected to one end of R7 and one end of R5. Its function is to set the overvoltage threshold for the first-level overvoltage protection circuit.

[0101] One end of R7 is connected to the positive electrode of D2 and one end of R5, and the other end is directly connected to GND. Its function is that when the VBAT voltage is too high, the current passes through R7 to generate a voltage VR7 on it. When the VR7 voltage is greater than the Vbe of Q3, Q3 is turned on. R7 provides the turn-on voltage when the first-level overvoltage protection circuit is effective.

[0102] One end of R5 is connected to the positive electrode of D2 and one end of R7, and the other end is connected to the base of Q3. Its function is to provide base limiting current for Q3, ensuring the safety of Q3 and not burning the transistor.

[0103] Q3 is a triode, whose base is connected to one end of R5, the emitter is directly connected to GND, and the collector is connected to one end of R3 and R8 and the base of Q2. Its function is that when the VBAT voltage is too high and exceeds the overvoltage threshold set by D2, Q3 is turned on to connect the base of Q2 to GND, keeping the base at a reliable low level, so that Q2 is turned off.

[0104] One end of R3 is connected to the control signal 1 of MCU, and the other end is connected to the collector of Q3, the base of Q2, and one end of R8. Its function is to provide the base current limiting resistor of Q2 when the switch circuit is turned on, and to provide the collector current limiting resistor of Q3 when the primary overvoltage protection circuit is effective.

[0105] One end of R8 is connected to the collector of Q3, one end of R3, and the base of Q2, and the other end is directly connected to GND. Its function is to ensure the stability of the base state of Q2.

[0106] Q2 is a triode, the base is connected to one end of R8 / R3 and the collector of Q3, the emitter is directly connected to GND, and the collector is connected to one end of R4. Its function is to ensure that the gate level of Q1 is low and the PMOS is reliably turned on after the overvoltage protection effective command is turned on.

[0107] One end of R4 is connected to the collector of Q2, and the other end is connected to one end of R1, the positive pole of D1, the gate of Q1, and the collector of Q5. Its function is to form a voltage divider circuit with R1, which ensures that the gate voltage of Q1 is less than the source voltage when Q2 is effective, so as to achieve the purpose of reliably turning on Q1.

[0108] One end of R1 is connected to VBAT, Q1 source, D1 / D2 / D3 cathode, and Q5 emitter, and the other end is connected to D1 anode, Q1 gate, Q5 collector, and one end of R4. Its function is the same as R4.

[0109] D1 is a voltage-stabilizing diode. Its cathode is connected to one end of R1, VBAT, and the source of Q1, and its anode is connected to one end of R1, one end of R4, and the gate of Q1. Its function is to prevent the gate and source voltages of Q1 from being clamped to a specific voltage value when the voltage is too high, to ensure that it does not exceed its maximum withstand voltage value.

[0110] Q1 is a PMOS tube, whose source is connected to VBAT, one end of R1, the negative pole of D1 / D2 / D3, and the emitter of Q5, whose gate is connected to one end of R4 / R1, the positive pole of D1, and the collector of Q5, and whose drain is connected to one end of R2. It serves as the main control device of this switching circuit.

[0111] One end of R2 is connected to the drain of Q1, and the other end is connected to one end of R6 to the diagnostic signal 2 of the MCU. Its function is to form a voltage divider circuit with R6 to collect the Q1 drain voltage VB_PR state through PORT2 of the MCU.

[0112] One end of R6 and one end of R2 are connected to diagnostic signal 2, and the other end is directly connected to GND. Its function is to form a voltage divider circuit with R2, and collect the state of Q1 drain voltage VB_PR through the diagnostic signal port 2 of MCU.

[0113] The positive pole of D3 is connected to one end of R9 and one end of R10, and the negative pole is connected to the negative pole of D1 / D2, the emitter of Q5, one end of R1, and the source of Q1. It serves as a setting device for the overvoltage protection threshold of the secondary overvoltage protection circuit.

[0114] One end of R9 is connected to the positive electrode of D3 and one end of R10, and the other end is directly connected to GND. Its function is that when the VBAT voltage is too high, the current passes through R9 to generate a voltage VR9 on it. When the VR9 voltage is greater than the Vbe of Q4, Q4 turns on. R9 provides the turn-on voltage when the secondary overvoltage protection circuit is effective.

[0115] One end of R10 is connected to the positive electrode of D3 and one end of R9, and the other end is connected to the base of Q4. Its function is to provide base limiting current for Q4, ensuring the safety of Q4 and not burning the transistor.

[0116] Q4 is an NPN transistor, whose base is connected to one end of R10, the emitter is directly connected to GND, and the collector is connected to one end of R11. Its function is that when the VBAT voltage is too high and exceeds the overvoltage threshold set by D3, Q4 is turned on to connect the base of Q5 to GND, keeping the base at a reliable low level, so that Q5 is turned on.

[0117] One end of R11 is connected to the collector of Q4, and the other end is connected to the base of Q5. Its function is to provide current limiting for the collector of Q4 and the base of Q5 to protect Q4 / Q5 when the secondary overvoltage protection circuit is effective.

[0118] The base of Q5 is connected to one end of R10, and the emitter is connected to the negative electrode of D1 / D2 / D3, one end of R1, and the source of Q1. Its function is that when the secondary overvoltage protection is effective, Q5 is turned on, making the gate and source voltages of Q1 equal, thereby reliably turning off Q1.

[0119] The specific working principle of the circuit in this embodiment is as follows:

[0120] 1. The controllable switch circuit consists of: MCU control signal 1, R3 / R8, R1 / R4, D1, Q2, Q1. The basic logic is as follows:

[0121] When VBAT is powered on (voltage is normal), all diodes and transistors are in the off state by default.

[0122] When the MCU controls the control signal 1 to output a high level, select the appropriate R3 / R8 resistance value so that the voltage divider value of R3 and R8 is greater than the start-up voltage of Q2, the Q2 transistor is turned on, R1 and R4 form a voltage divider circuit, and select the appropriate resistance value so that the voltage difference on R1 is greater than the start-up voltage of Q1 and less than the maximum withstand voltage of Q1, thereby ensuring the reliable start-up of Q1. At this time, VB_PR = VBAT, and the MCU diagnostic signal 2 collects the VB_PR level to be high.

[0123] 2. The first-level overvoltage protection circuit is composed of: D2, R7, R5, Q3, and its principle is as follows:

[0124] When the VBAT voltage exceeds the overvoltage threshold set by D2, the D2 Zener diode is in the avalanche region. When the current passing through R7 reaches a certain value, VR7 is greater than the base turn-on level of Q3, Q3 is turned on, and the base of Q2 is connected to GND. Q2 is turned off, and Q1 will also be turned off.

[0125] 3. The secondary protection circuit consists of: D3, R9, R10, Q4, R11, and Q5.

[0126] When the VBAT voltage exceeds the overvoltage threshold set by D3, the D3 Zener diode is in the avalanche region. When the current passing through R9 reaches a certain value, VR9 is greater than the base turn-on level of Q4, Q4 is turned on, and the base of Q5 is connected to GND, Q5 is turned on, and the gate and source voltages of Q1 are equal, so it will also be turned off.

[0127] The selection of D2 and D3 should satisfy the following requirements as far as possible: the voltage regulation value of D3 should be greater than or equal to the voltage regulation value of D2, and sufficient margin should be left for the withstand voltage of the subsequent load of the switch.

[0128] Since the overvoltage protection circuit needs to work in a harsh high-voltage environment, if the voltage is too high and far exceeds the tolerance limit of the first-level overvoltage protection circuit, or if the device is damaged or welding is abnormal due to other reasons, the overvoltage protection function will fail. Moreover, the first-level overvoltage protection circuit can only act on the base of Q2, and cannot directly act on the switch position of Q1, so there is a possibility of other failures. Therefore, the first-level overvoltage protection circuit has the risk of failure.

[0129] Therefore, a secondary overvoltage protection circuit is introduced. Its working mechanism is similar to that of the primary overvoltage protection circuit, but the devices it acts on form a complementary relationship with it, which makes up for the shortcoming of insufficient coverage of failed component points and also achieves a redundant protection mechanism.

[0130] It should be noted that for switching devices, those skilled in the art can understand that for NPN transistors, the current relationship flowing through the collector (c), base (b), and emitter (e) is: Ie=Ib+Ic, Ic=β*Ib. When Ube>0.7V, that is, the emitter junction voltage Ube is forward biased, the transistor is turned on. When Ube<0.7V, that is, the emitter junction voltage Ube is reverse biased, the transistor is in a cut-off state, which is equivalent to the switch being disconnected. Among them, the transistor conduction voltage and other parameters are determined by the specific device selected. Correspondingly, the parameters of each voltage divider circuit are also selected according to the specification requirements of the device. This is common sense for those skilled in the art and will not be repeated. Similarly, for PNP transistors, when Ube<-0.7V, the transistor is turned on. When Ube>-0.7V, the transistor is turned off. Similarly, the specific circuit parameters need to be determined with reference to the specification requirements of the selected transistor.

[0131] It should be understood by those skilled in the art that the MOS tube needs to meet the condition of |Vg-Vs|>|Vgs(TH)| for it to be turned on. Specifically, for NMOS tubes, Vg-Vs>Vgs(TH), Vgs(TH) is the threshold voltage of the MOS tube, that is, the voltage difference between the G pole (gate) and the S pole (source) is greater than a certain value, the MOS tube will be turned on, but the voltage difference cannot be too large, otherwise the MOS tube will be burned out. Among them, the turn-on voltage and other parameters need to refer to the relevant specifications according to the specific device selected. Similarly, for PMOS tubes, Vg-Vs<Vgs(TH), that is, the voltage difference between the G pole and the S pole is less than a certain value, the MOS tube will be turned on (for PMOS tubes, Vgs(TH) is a negative value). Similarly, the specific parameters need to refer to the specifications of the specific device.

[0132] The utility model provides an overvoltage protection circuit, which has the function of preventing the failure of the overvoltage protection function and realizing the function of safely and reliably opening or closing the switch circuit. The core point is that a secondary redundant protection mechanism is added after the primary overvoltage protection part. The primary protection is a disable control signal, and the secondary protection directly disables the MOS switch part, which can maximize the protection of the safety of the subsequent load and achieve the purpose of preventing the failure of the overvoltage protection function.

[0133] In addition, the utility model also adds detection and protection mechanisms in both software and hardware. First, the switch of the overvoltage protection circuit is realized by software, and status detection is added to monitor the status of the switching device. When the voltage abnormality is monitored, the output control can be turned off, thereby achieving the purpose of improving the reliability of the overvoltage protection circuit.

[0134] Furthermore, as mentioned above, the utility model adds a secondary overvoltage protection circuit in hardware. The circuit logically covers most of the failure points, can directly shut down the switching devices, effectively improve the circuit reliability, and realize hardware redundancy, making the protection function more reliable.

[0135] Therefore, the overvoltage protection circuit provided by the utility model has at least the following beneficial effects:

[0136] 1. The overvoltage protection circuit can be opened and closed normally.

[0137] 2. Add redundant secondary overvoltage protection hardware logic to prevent functional failure caused by failure of a single functional component, thereby improving the safety of the system.

[0138] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "embodiment", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0139] In the present invention, the terms "connected", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model and are not restrictive. Although the utility model is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solution of the utility model does not deviate from the spirit and scope of the technical solution of the utility model, and should be included in the scope of the claims of the utility model.

Claims

1. An overvoltage protection circuit, used to protect at least a switching device and a subsequent load connected to an output terminal of the switching device, characterized in that: The circuit comprises: A switch control module includes a switch control device connected to a control terminal of the switch device, wherein the switch device is turned on or off by the on or off control of the switch control device. a first overvoltage protection module connected to the control terminal of the switch control device and the power supply, wherein when the operating voltage of the power supply connected to the switch device exceeds a first overvoltage threshold defined by the first overvoltage protection module, the first overvoltage protection module is configured to shut down the switch control device; A second overvoltage protection module is connected to the power supply and the control end of the switch device, wherein when the operating voltage of the power supply exceeds a second overvoltage threshold defined by the second overvoltage protection module, the second overvoltage protection module is configured to turn off the switch device.

2. The overvoltage protection circuit according to claim 1, characterized in that: The switch control module is also connected to a signal input terminal for receiving a control signal, and the switch control device is turned on or off according to a high level or a low level state of the control signal.

3. The overvoltage protection circuit according to claim 2, characterized in that: The circuit also includes a signal diagnosis module with one end connected to the output end of the switch device and the other end grounded, which is used to collect the output voltage of the switch device and control the control signal received by the signal input end to be low level when the output voltage is abnormal.

4. The overvoltage protection circuit according to claim 3, characterized in that: The first overvoltage threshold does not exceed the second overvoltage threshold.

5. The overvoltage protection circuit according to claim 4, characterized in that: The first overvoltage protection module includes a first overvoltage threshold limiting device that defines the first overvoltage threshold and a first switch protection device, the first overvoltage threshold limiting device is connected to the control end of the first switch protection device, and the first switch protection device is connected to the control end of the switch control device, so that the switch control device is controlled to be turned off by the first switch protection device according to the overvoltage state of the first overvoltage threshold limiting device. The second overvoltage protection module includes a second overvoltage threshold limiting device that limits the second overvoltage threshold, a second switch protection device, and a third switch protection device. One end of the second overvoltage threshold limiting device is connected to a power supply, and the other end is connected to a control end of the second switch protection device. The second switch protection device is connected to the control end of the third switch protection device, and the third switch protection device is connected to the control end of the switch device, so that the switch device is controlled to be turned off by the second switch protection device and the third switch protection device according to the overvoltage state of the second overvoltage threshold limiting device.

6. The overvoltage protection circuit according to claim 5, characterized in that: The switch control module also includes a first voltage divider circuit and a second voltage divider circuit. The switch control device is turned on by the first voltage divider circuit and the switch device is controlled to be turned on or off by the second voltage divider circuit. The first voltage divider circuit includes a first series resistor with one end connected to the signal input end and the other end grounded, and the connection end of the two resistors in the first series resistor is connected to the control end of the switch control device; the second voltage divider circuit includes a second series resistor with one end connected to the power supply and the other end connected to the switch control device, and the connection end of the two resistors in the second series resistor is connected to the control end of the switch device. and / or The first overvoltage protection module also includes a third voltage divider circuit, wherein the first switch protection device in the first overvoltage protection module is turned on through the third voltage divider circuit, wherein the third voltage divider circuit includes a third series resistor having one end connected to the first switch protection device and the other end grounded, the connection end of two resistors in the third series resistor is connected to the first overvoltage threshold limiting device, and the other end of the first overvoltage threshold limiting device is connected to the power supply, and / or The second overvoltage protection module also includes a fourth voltage divider circuit, the second switch protection device in the second overvoltage protection module is turned on by the fourth voltage divider circuit, and the turn-off of the switch device is controlled by the turn-on of the third switch protection device, wherein the fourth voltage divider circuit includes a fourth series resistor with one end grounded and the other end connected to the control end of the second switch protection device, the connection end of two resistors in the fourth series resistor is connected to the second overvoltage threshold limiting device, and the other end of the second overvoltage threshold limiting device is connected to the power supply, and / or The signal diagnosis module also includes a fifth voltage-dividing circuit, which includes a fifth series resistor having one end connected to the output end of the switching device and the other end grounded, wherein the connection end of the two resistors in the fifth series resistor is the collection end of the output voltage of the switching device.

7. The overvoltage protection circuit according to claim 5 or 6, characterized in that: It also includes a protection device having one end connected to the control end of the switch device and the other end connected to the power supply.

8. The overvoltage protection circuit according to claim 7, characterized in that: The switching device is a PMOS field effect transistor. The switch control device, the first switch protection device, the second switch protection device, and the third switch protection device are PNP type transistors. The protection device, the first overvoltage threshold limiting device and the second overvoltage threshold limiting device are voltage stabilizing diodes. The source of the switch device is connected to the power supply, the gate is connected to the connection end of two resistors of the second series resistor in the second voltage divider circuit, and the drain is connected to the subsequent load; The base of the switch control device is connected to the connection end of the two resistors of the first series resistor in the first voltage divider circuit and the collector of the first switch protection device, the collector is connected to the gate of the switch device through a resistor in the second voltage divider circuit, and the emitter is grounded; The emitter of the first switch protection device is grounded, the base is connected to the third series resistor, and is connected to the positive electrode of the first overvoltage threshold limiting device through a resistor in the third series resistor, and the negative electrode of the first overvoltage threshold limiting device is connected to the power supply; The emitter of the second switch protection device is grounded, the base is connected to the fourth series resistor, and is connected to the positive electrode of the second overvoltage threshold limiting device through a resistor in the fourth series resistor, the collector is connected to the base of the third switch protection device through a resistor, and the negative electrode of the second overvoltage threshold limiting device is connected to the power supply; The emitter of the third switch protection device is connected to the power supply, the collector is connected to the gate of the switch device and the positive electrode of the protection device, and the negative electrode of the protection device is connected to the power supply.

9. A vehicle equipment power supply control device, characterized in that: The invention comprises an overvoltage protection circuit according to any one of claims 1 to 8.

10. A mobile tool, characterized in that: It comprises the vehicle equipment power supply control circuit according to claim 9.

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