Protection circuit for vehicle body control module

Abstract

The utility model provides a protection circuit for an automobile body control module, which relates to the technical field of automobile circuit protection and comprises a power supply, a protection unit, a load and an external CPU (central processing unit). The power supply is electrically connected with the protection unit, and the protection unit is electrically connected with the load and the external CPU. The protection unit comprises a monitoring subunit, a main loop Mosfet, a pre-charging Mosfet and a driving chip; the monitoring subunit comprises a current monitoring part, a temperature monitoring part and a voltage monitoring part; the current monitoring part is electrically connected with the driving chip and the external CPU respectively, and the driving chip is electrically connected with the main loop Mosfet, the pre-charging Mosfet, the external CPU, the temperature monitoring part and the voltage monitoring part respectively. The electronic fuse solves the problems that a traditional fuse is low in response speed and unrecoverable, and an existing electronic fuse is complex in structure and cannot support large-current circuit protection.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of automobile circuit protection, especially relates to a protection circuit for body control module. BACKGROUND

[0002] With the rapid development of automobile electronic technology, the body control module (BCM) as the core pivot of the whole vehicle electrical system, its circuit protection reliability is directly related to the vehicle safety and maintenance cost. The traditional fuse type fuse adopts physical fusing mechanism in overcurrent protection, although it has the characteristics of simple structure, but there are inherent defects such as slow response speed (typical response time > 100 ms), non-recovery after fusing. Especially under the condition of transient current impact, the delay action caused by thermal inertia is easy to cause the cumulative damage of the rear-end precision electronic components. More prominent is that the single protection characteristic of the fuse forces the vehicle to be manually maintained and replaced, which significantly increases the after-sales maintenance cost in the distributed layout of the body circuit.

[0003] Although the electronic fuse (eFuse) chip appeared in recent years can realize automatic recovery function, its technical architecture has multiple limitations: on the one hand, the scheme relying on special control chip leads to the sharp increase of hardware cost, and most commercial devices only support fixed threshold or one-time programming (OTP), which cannot adapt to the dynamic load characteristics of the body circuit; on the other hand, limited by the current-carrying capacity and thermal design redundancy of power devices, the maximum continuous working current of existing eFuse products is generally lower than 20A, which is difficult to meet the protection requirements of large current circuits (> 30A) such as window drive and seat adjustment. More importantly, the overcurrent judgment logic of the traditional electronic fuse is based on preset fixed parameters, which lacks the self-adaptive ability to the actual working conditions such as wire harness aging and contact resistance change, and is easy to cause misoperation or protection failure.

[0004] Therefore, a protection circuit for body control module is proposed. UTILITY MODEL CONTENTS

[0005] The present specification provides a protection circuit for body control module, which solves the problems of slow response speed of traditional fuse, non-recovery and complex structure of existing electronic fuse, and cannot support large current circuit protection.

[0006] The present specification provides a protection circuit for body control module, which comprises:

[0007] A power supply, a protection unit, a load and an external CPU; the power supply is electrically connected with the protection unit, and the protection unit is respectively electrically connected with the load and the external CPU;

[0008] The protection unit comprises a monitoring subunit, a main loop Mosfet, a pre-charge Mosfet and a driving chip; the monitoring subunit comprises a current monitoring element, a temperature monitoring element and a voltage monitoring element;

[0009] The current monitoring element is electrically connected with the driving chip and the external CPU respectively, and the driving chip is electrically connected with the main loop Mosfet, the pre-charge Mosfet, the external CPU, the temperature monitoring element and the voltage monitoring element respectively.

[0010] Optionally, the main loop Mosfet adopts a back to back topology structure, and the withstand voltage is greater than or equal to 60V, which is suitable for high current transmission in a 24V system.

[0011] Optionally, the back to back topology structure comprises a common source topology structure and / or a common drain topology structure.

[0012] Optionally, the common source topology structure comprises a Mos tube D3 and a Mos tube D4, and the source of the Mos tube D3 is electrically connected with the source of the Mos tube D4.

[0013] Optionally, the common drain topology structure comprises a Mos tube D1 and a Mos tube D2, and the drain of the Mos tube D1 is electrically connected with the drain of the Mos tube D2.

[0014] Optionally, the pre-charge Mosfet has a withstand voltage greater than or equal to 60V, which is suitable for low current transmission in a pre-charge loop.

[0015] Optionally, the temperature monitoring element comprises an NTC thermistor.

[0016] In the utility model, through the time-sharing switching design of the main path and the pre-charge path, the surge suppression and high efficiency are taken into account. The main path is used for high current transmission in normal work, and the pre-charge path is used for surge current limitation in starting. The integrated current, voltage and temperature three-in-one monitoring function is used for real-time detection of abnormal conditions such as overcurrent, overvoltage and overtemperature, and the system reliability is improved. Through the dynamic configuration of protection parameters such as overcurrent threshold, overvoltage threshold and fault recovery time by the external CPU, the adaptability and flexibility of the circuit are enhanced. The devices are independent of each other, which is convenient for maintenance and parameter adjustment, and reduces the maintenance cost. The circuit structure with interchangeable load end and input end is designed, so that the circuit system is not damaged after being connected reversely by the user, and the safety and reliability of the circuit are improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0018] Figure 1 The structural schematic diagram of the protection circuit for the body control module is provided for the embodiment of the present specification.

[0019] Figure 2 The principle schematic diagram of the back to back topology is provided for the embodiment of the present specification.

[0020] The drawings show: 10, power supply; 21, current monitoring member; 22, temperature monitoring member; 23, voltage monitoring member; 30, driving chip; 40, main loop MOSFET; 50, pre-charge MOSFET; 60, external CU; 70, load. DETAILED DESCRIPTION

[0021] The following description is used to disclose the present application so that those skilled in the art can implement the present application. The preferred embodiments in the following description are only used as examples, and other obvious modifications can be thought by those skilled in the art. The basic principles of the present application defined in the following description can be applied to other embodiments, modifications, improvements, equivalents and other technical solutions without departing from the spirit and scope of the present application.

[0022] The following description is used to disclose the present application so that those skilled in the art can implement the present application. The preferred embodiments in the following description are only used as examples, and other obvious modifications can be thought by those skilled in the art. The basic principles of the present application defined in the following description can be applied to other embodiments, modifications, improvements, equivalents and other technical solutions without departing from the spirit and scope of the present application. Figures 1-2 Exemplary embodiments of the present application are more fully described. However, exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these exemplary embodiments are provided so that the present application will be more thoroughly and completely conveyed to those skilled in the art, and so that the present application will be better understood. Like reference numerals in the drawings denote like or similar elements, components, or parts, and thus repeated description thereof will be omitted.

[0023] Under the premise of conforming to the technical concept of the present application, the features, structures, characteristics or other details described in a certain specific embodiment do not exclude that they can be combined in one or more other embodiments in a suitable manner.

[0024] In the description of specific embodiments, the features, structures, characteristics or other details described by the present application are to enable those skilled in the art to fully understand the embodiments. However, it does not exclude that those skilled in the art can practice the technical solutions of the present application without one or more specific features, structures, characteristics or other details.

[0025] The flowcharts shown in the drawings are merely illustrative and do not necessarily include all contents and operations / steps, nor are they necessarily executed in the order described. For example, some operations / steps can be further divided, and some operations / steps can be combined or partially combined, so the actual execution order can be changed according to actual conditions.

[0026] The block diagrams shown in the drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0027] The term "and / or" or "or" includes all combinations of one or more of the associated listed items.

[0028] Figure 1 A structural diagram of a protection circuit for a body control module is provided for an embodiment of the present specification, comprising:

[0029] A power supply, a protection unit, a load, and an external CPU; the power supply is electrically connected to the protection unit, and the protection unit is respectively electrically connected to the load and the external CPU;

[0030] The protection unit includes a monitoring subunit, a main loop Mosfet, a pre-charge Mosfet, and a driving chip; the monitoring subunit includes a current monitoring member, a temperature monitoring member, and a voltage monitoring member;

[0031] The current monitoring member is respectively electrically connected to the driving chip and the external CPU, and the driving chip is respectively electrically connected to the main loop Mosfet, the pre-charge Mosfet, the external CPU, the temperature monitoring member, and the voltage monitoring member.

[0032] In the detailed description of the present specification, the pre-charge Mosfet adopts a back to back topology structure for limiting the inrush current at start-up and realizing the soft start function. The monitoring subunit monitors the main path current, input voltage and load end voltage, and circuit working temperature in real time. The driving chip supports the main loop and pre-charge loop MOSFET control, and ensures that the chip has sufficient multi-channel driving output and overcurrent / overvoltage protection functions. The GA / GB pins of the driving chip are connected to the main path and pre-charge path MOSFET gates respectively, and a common-source back-to-back topology is adopted; the gate resistor is selected to be 10Ω, which matches the output current capability of the driving chip (typical value 175mA@on, 1400mA@off). The voltage monitoring piece adopts a resistor divider network (such as R1=10kΩ, R2=1kΩ) to divide the main loop voltage (such as 28V) to within the acceptable range of the driving chip (such as 2.8V), and feedback to the driving chip and external CPU. The current monitoring piece is connected in series with a sampling resistor (such as 0.01Ω / 5W) in the main loop, and the current signal is input to the driving chip and external CPU after being amplified by a differential amplifier. Some driving chips have overcurrent detection function, which only needs to configure the related peripheral circuit according to its characteristics.

[0033] Optionally, the pre-charge Mosfet has a withstand voltage greater than or equal to 60V, suitable for low current transmission in the pre-charge loop.

[0034] Optionally, the temperature monitoring piece includes an NTC thermistor.

[0035] In the detailed description of the present specification, the NTC thermistor is placed near the MOSFET on the PCB to monitor the temperature change in real time; the temperature signal is input to the driving chip and external CPU through the ADC.

[0036] In the detailed description of the present specification,

[0037] Figure 2 The principle diagram of the back to back topology structure provided by the embodiment of the present specification includes:

[0038] Optionally, the main loop Mosfet adopts a back to back topology structure, which has a withstand voltage greater than or equal to 60V, suitable for high current transmission in a 24V system.

[0039] In the detailed description of the present specification, the main loop MOSFET adopts a back-to-back connection (Back-to-Back) topology to prevent reverse current impact. By connecting multiple pairs of MOSFET switching tubes in parallel, the current passing capacity can be improved (such as increasing 60A of current capacity for each additional pair of MOSFET). The current level of the pre-charge loop MOSFET can be appropriately reduced (such as 20A) to save cost.

[0040] Optionally, the back to back topology includes a common source topology and / or a common drain topology.

[0041] In the detailed description of the present specification, the common source can use one control signal, and the common drain needs to use two control signals.

[0042] Optionally, the common source topology includes a Mos tube D3 and a Mos tube D4; the source of the Mos tube D3 is electrically connected with the source of the Mos tube D4.

[0043] Optionally, the common drain topology includes a Mos tube D1 and a Mos tube D2; the drain of the Mos tube D1 is electrically connected with the drain of the Mos tube D2.

[0044] At the power-on moment, the drive chip controls the pre-charge MOSFET to be turned on, and the main loop MOSFET is turned off, so as to slowly charge the load capacitor through the current-limiting resistor (such as 10Ω), thereby avoiding the surge current impact. When the voltage of the load capacitor approaches the power supply voltage (such as 22V), the drive chip turns off the pre-charge MOSFET and turns on the main loop MOSFET, and enters the normal power supply mode. In the running process, the drive chip compares the voltage, current and temperature signals with the set threshold value (such as the overcurrent threshold value 200A, the overvoltage threshold value 28V and the overtemperature threshold value 85℃) in real time, and if any signal is out of limit, the main loop MOSFET is immediately turned off to protect the load end equipment. When the fault is eliminated, the drive chip automatically or through the external CPU instruction re-enters the pre-charge mode, and gradually restores the power supply.

[0045] In the utility model, through the time-sharing switching design of the main path and the pre-charge path, the surge suppression and high efficiency are taken into account. The main path is used for high current transmission in normal work, and the pre-charge path is used for surge current limitation in starting. The integrated current, voltage and temperature three-in-one monitoring function is used to detect abnormal conditions such as overcurrent, overvoltage and overtemperature in real time, and the system reliability is improved. The external CPU dynamically configures protection parameters such as overcurrent threshold value, overvoltage threshold value and fault recovery time, and the adaptability and flexibility of the circuit are enhanced. The devices are independent of each other, which is convenient for maintenance and parameter adjustment, and reduces the maintenance cost. The circuit structure with interchangeable load end and input end is designed, so that the user can avoid damaging the circuit system after connecting reversely, and the safety and reliability of the circuit are improved.

[0046] The above-described specific embodiments further specifically describe the purposes, technical solutions and advantages of the present application, and it should be understood that the present application is not inherently related to any specific computer, virtual device or electronic device, and various general-purpose devices can also implement the present application. The above-described is only a specific embodiment of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0047] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the difference from other embodiments.

[0048] The above-described is only an embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A protection circuit for a vehicle body control module, characterized in that, include: The power supply (10), protection unit, load (70), and external CPU (60) are included. The power supply (10) is electrically connected to the protection unit, and the protection unit is electrically connected to the load (70) and the external CPU (60) respectively. The protection unit includes a monitoring subunit, a main circuit MOSFET (40), a pre-charge MOSFET (50), and a driver chip (30); the monitoring subunit includes a current monitoring device (21), a temperature monitoring device (22), and a voltage monitoring device (23); The current monitoring device (21) is electrically connected to the driving chip (30) and the external CPU (60) respectively. The driving chip (30) is electrically connected to the main circuit MOSFET (40), the pre-charge MOSFET (50), the external CPU (60), the temperature monitoring device (22), and the voltage monitoring device (23) respectively.

2. The protection circuit for the vehicle body control module as described in claim 1, characterized in that, The main circuit MOSFET (40) adopts a back-to-back topology and has a withstand voltage greater than or equal to 60V, which is suitable for high current transmission in a 24V system.

3. The protection circuit for the vehicle body control module as described in claim 2, characterized in that, The back-to-back topology includes a common-source topology and / or a common-drain topology.

4. The protection circuit for the vehicle body control module as described in claim 3, characterized in that, The common-source topology includes MOSFET D3 and MOSFET D4; the source of MOSFET D3 is electrically connected to the source of MOSFET D4.

5. The protection circuit for the vehicle body control module as described in claim 4, characterized in that, The common-drain topology includes MOSFET D1 and MOSFET D2; the drain of MOSFET D1 is electrically connected to the drain of MOSFET D2.

6. The protection circuit for the vehicle body control module as described in claim 4, characterized in that, The precharged MOSFET (50) has a withstand voltage greater than or equal to 60V, making it suitable for low current transmission in the precharge circuit.

7. The protection circuit for the vehicle body control module as described in claim 4, characterized in that, The temperature monitoring device (22) includes an NTC thermistor.

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