A short circuit protection circuit and test device based on BMS

Abstract

The utility model discloses a short-circuit protection circuit and test device based on BMS. The circuit absorbs the surge generated by the short circuit in the BMS circuit, can protect the lithium battery and the BMS when a short circuit occurs, can quickly and effectively cut off the circuit when a short circuit occurs in the lithium battery, and plays a role in protecting personal safety and public property. It can protect the lithium battery from the hazards of short circuit at low cost, safely and effectively. After a short circuit occurs, the battery and the BMS can work normally, and will not affect subsequent use.

Description

Technical Field

[0001] The utility model relates to the technical field of BMS, in particular to a short-circuit protection circuit and a test device based on BMS. Background Art

[0002] As an indispensable energy source in today's world, lithium batteries have outstanding advantages such as light weight and easy to carry, and are applied to various fields of society, such as automobiles, mobile phones, computers, etc. Among power batteries, lithium batteries have many outstanding advantages over other batteries and are widely used. With the research on lithium batteries, people gradually understand the various characteristics of lithium batteries. Lithium batteries have the characteristics of high voltage, light weight and high energy density, and can be charged quickly. They have developed rapidly in modern society and have been applied in various fields of society.

[0003] In recent years, lithium-ion batteries have developed rapidly, and their application fields are wide, covering electric vehicles, energy storage, and various types of power tools. Among them, the industrial scale of new energy vehicles, energy storage and other fields will maintain an exponential growth trend in the next few years, which will greatly stimulate the production demand of lithium-ion batteries. In the era of expanding production demand for lithium batteries, lithium battery protection technology has also improved. According to some market research, the protection functions of lithium battery protection boards (BMS) on the market are mainly overcurrent protection, overvoltage protection, high voltage protection, and battery cell overtemperature protection. Most of the BMS protection boards either do not have this function for short-circuit protection, or just stay in the state of using equipment to simulate battery short circuits. It does not take into account what happens in actual scenarios. Utility Model Content

[0004] In view of this, the purpose of the utility model is to provide a short-circuit protection circuit and a test device based on BMS, which utilizes a surge protection module to enable the BMS to protect the lithium battery when a short circuit occurs.

[0005] In order to achieve the above object, the utility model provides the following technical solutions:

[0006] The utility model provides a short-circuit protection circuit based on BMS, including a microcontroller chip, a discharge control module, a charge control module and a surge protection module.

[0007] The microcontroller chip is connected to the discharge control module and the charge control module respectively;

[0008] The surge protection module is connected to the discharge control module and the charge control module;

[0009] The discharge control module is used to control the discharge process of the battery;

[0010] The charging control module is used to control the charging process of the battery;

[0011] The surge protection module is used to absorb surge when a short circuit occurs in the battery.

[0012] Furthermore, it also includes a voltage overcharge protection module connected to the microcontroller chip;

[0013] The voltage overcharge and over-protection module is used to collect the voltage of a single battery cell in real time, and block the input and output of the battery when the battery voltage is abnormal.

[0014] Furthermore, it also includes a temperature protection module connected to the microcontroller chip;

[0015] The temperature protection module is used to connect an external temperature resistor to collect the battery temperature and realize the temperature protection function.

[0016] Furthermore, it also includes a current acquisition module connected to the microcontroller chip;

[0017] The current acquisition module is used to acquire the current in real time.

[0018] Furthermore, it also includes a chip power supply and a program burning port connected to the microcontroller chip;

[0019] The chip power supply is used to provide power to the microcontroller chip;

[0020] The program burning port is used to input external programs into the microcontroller chip.

[0021] Further, the surge protection module includes a diode group, a series capacitor group, and a MOS field effect transistor;

[0022] One end of the diode group is connected to the source of the MOS field effect tube of the charging control module, and the other end is connected to the drain of the MOS field effect tube of the charging control module; the gate of the MOS field effect tube is connected to the temperature protection module through a resistor;

[0023] One end of the series capacitor group is connected to the source of the MOS field effect tube of the charging control module, and the other end is connected to the source of the MOS field effect tube of the discharging control module;

[0024] The drain of the MOS field effect tube of the charging control module is connected to the drain of the MOS field effect tube of the discharging control module.

[0025] Further, the discharge control module includes a discharge driving unit and a discharge execution unit;

[0026] The discharge driving unit is used to provide a driving signal to the discharge execution device; the discharge execution unit is used to control the discharge and closing process;

[0027] The discharge driving unit comprises a first triode and a second triode; the emitters of the first triode and the second triode are connected and then connected to the discharge execution unit through a resistor; the base of the first triode is connected to the microcontroller chip through a resistor; the bases of the first triode and the second triode are connected and then respectively connected to the resistor connected in series to the collector through a resistor; that is, the bases of the first triode and the second triode are connected; the base of the first triode is connected to the resistor connected in series to the collector through a resistor; the base of the second triode is connected to the resistor connected in series to the collector through a resistor;

[0028] The discharge execution unit includes a plurality of parallel branches, each of which includes a MOS tube, a gate of which is connected to the discharge driving unit through a resistor; a source of the MOS tube is connected to the source of the MOS tubes of other branches; a drain of the MOS tube is connected to the drain of the MOS tubes of other branches and then connected to the charge execution unit.

[0029] Furthermore, the charging control module includes a charging drive unit and a charging execution unit; the charging drive unit is used to provide a driving signal to the charging execution device; the charging execution unit is used to control the discharge and shutdown process;

[0030] The charging drive unit includes a third transistor, a fourth transistor, a first diode, and a second diode;

[0031] The base of the third triode is connected to the ground through a resistor; the emitter of the third triode is connected to the microcontroller chip; a resistor is connected between the base and emitter of the third triode; the collector of the third triode is connected to the positive electrode of the first diode, and the negative electrode of the first diode is connected to the positive electrode of the second diode; the negative electrode of the second diode is connected to the emitter of the fourth triode; the collector of the fourth triode is connected to the charging execution unit through a resistor; a resistor is connected between the base and collector of the fourth triode; the base of the fourth triode is connected to the negative electrode of the first diode;

[0032] The charging execution unit includes a plurality of parallel branches, each of which includes a MOS tube, a gate of the MOS tube being connected to the cathode of the first diode of the charging driving unit through a resistor; a source of the MOS tube being connected to the source of the MOS tubes of other branches; and a drain of the MOS tube being connected to the drain of the MOS tubes of other branches and then connected to the discharge execution unit.

[0033] The utility model provides a test device constructed according to the above-mentioned BMS-based short-circuit protection circuit, which includes a battery pack, a BMS-based short-circuit protection circuit, and an air switch; one end of the short-circuit protection circuit is connected to the negative electrode of the battery pack, and the other end is connected to the positive electrode of the battery pack through the air switch.

[0034] The beneficial effects of the utility model are:

[0035] The utility model provides a short-circuit protection circuit and test device based on BMS. The circuit absorbs the surge generated by the short circuit in the BMS circuit, which can protect the lithium battery and BMS when a short circuit occurs. When a lithium battery short circuit occurs, the circuit can be quickly and effectively cut off, which plays a role in protecting personal safety and public property. It can protect the lithium battery from the hazards of short circuit at low cost, safely and effectively. After a short circuit occurs, the battery and BMS can work normally, which does not affect subsequent use.

[0036] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and will be apparent to those skilled in the art based on the following examination and research, or can be taught from the practice of the present invention to some extent. The objectives and other advantages of the present invention can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the purpose, technical solution and beneficial effects of the utility model clearer, the utility model is described with the following drawings:

[0038] Figure 1 This is a short-circuit protection circuit diagram based on BMS.

[0039] Figure 2 This is the overall circuit structure diagram.

[0040] Figure 3 This is the structure diagram of the surge protection module.

[0041] Figure 4 Voltage overcharge and overdischarge protection module.

[0042] Figure 5 It is a temperature protection module.

[0043] Figure 6 It is the current acquisition module.

[0044] Figure 7 It is the discharge control module.

[0045] Figure 8 It is the charging control module.

[0046] Fig. 9 Provides power to the chip and a port for burning programs.

[0047] Fig.10 This is the short circuit test circuit diagram.

[0048] In the figure, 1-short-circuit surge absorption module; 2-filter module; 31-discharge drive unit, 32-discharge execution unit; 33-first transistor, 34-second transistor; 41-charge drive unit, 42-charge execution unit, 43-third transistor, 44-fourth transistor, 45-first diode, 46-second diode; 5-battery positive pole, 6-battery negative pole, 7-short-circuit protection board, 8-air switch. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0050] like Figure 1 and Figure 2 As shown, Figure 1 The short-circuit protection circuit diagram based on BMS is provided in this embodiment, which includes a microcontroller chip and a voltage overcharge protection module, a temperature protection module, a current acquisition module, a discharge control module, a charge control module, a chip power supply and a program burning port connected to the microcontroller chip; and also includes a surge protection module, which is connected to the discharge control module and the charge control module;

[0051] The voltage overcharge protection module is used to collect the voltage of a single battery cell in real time, and block the input and output of the battery when the battery voltage is abnormal;

[0052] The temperature protection module is used to connect an external temperature resistor to collect the battery temperature and realize the temperature protection function;

[0053] The current acquisition module is used to collect the current in real time.

[0054] Size to achieve discharge overcurrent and charge overcurrent, as well as short circuit protection functions;

[0055] The discharge control module is used to control the discharge process of the battery;

[0056] The surge protection module is connected to the discharge control module and the charge control module respectively, and the discharge control module and the charge control module are connected to the microcontroller chip respectively; the surge protection module is used to absorb surges when a short circuit occurs in the battery, so as to protect the discharge control module and the charge control module from being damaged;

[0057] The charging control module is used to control the charging process of the battery;

[0058] The chip power supply is used to provide power to the microcontroller chip;

[0059] The program burning port is used to input external programs into the microcontroller chip;

[0060] The circuit of this embodiment adds a surge absorber generated by a short circuit in the BMS circuit, which can protect the lithium battery and the BMS when a short circuit occurs. The circuit principle is as follows: During normal circuit operation, a certain surge voltage will be generated when the circuit is turned off. This surge voltage is related to the discharge current released before the battery is turned off. The larger the current in the circuit, the larger the surge voltage generated. Therefore, when the battery is short-circuited, since the load outside the battery is short-circuited, its resistance approaches 0 ohms, so the current generated is extremely large. If the circuit cannot be effectively shut down, there is a high possibility of fire and explosion. The short-circuit protection principle is to release the high voltage generated when the short-circuit protection is turned off through the transient suppression diode in the circuit.

[0061] Figure 3 The structure diagram of the surge protection module is shown in FIG. 1 , wherein the surge protection module includes a diode group and a series capacitor group;

[0062] One end of the diode group is connected to the source of the MOS field effect tube of the charging control module, and the other end is connected to the drain of the MOS field effect tube of the charging control module; the gate of the MOS field effect tube is connected to the temperature protection module through a resistor;

[0063] One end of the series capacitor group is connected to the source of the MOS field effect tube of the charging control module, and the other end is connected to the source of the MOS field effect tube of the discharging control module;

[0064] The drain of the MOS field effect tube of the charging control module is connected to the drain of the MOS field effect tube of the discharging control module;

[0065] Figure 3 1 is the short-circuit surge absorption module; its function is to shut down the discharge MOS in about 460uS after the output circuit is short-circuited. Because a huge current will be generated when the circuit is short-circuited, the motherboard will generate an instantaneous surge after cutting off the circuit. The transient suppression diode of this module will absorb this surge to protect the MOS tube; 2 is the filtering module; it eliminates various high-frequency interference filtering and anti-interference in the circuit.

[0066] This circuit provides a voltage overcharge protection module, a temperature protection module, a current acquisition module, a discharge control module, a charging control module, a chip power supply, and a circuit structure of a program burning port; it can realize overcharge, over-discharge, overcurrent protection, temperature protection, and short-circuit protection of the battery pack. Overcharge protection: refers to the real-time detection of the battery's charging voltage during the charging process, and the battery can only be charged within the allowed voltage range, otherwise it cannot be charged. Over-discharge protection: refers to the real-time detection of the battery's discharge voltage during the discharge process, and the battery can only be discharged within the allowed voltage range, otherwise it cannot be discharged. Overcurrent protection: refers to the maximum allowable current of the battery during the charging and discharging process. If the range is exceeded, the protection will be activated and the charging and discharging will not be possible. Temperature protection: refers to the battery can only be charged and discharged within the appropriate temperature range, and the charging and discharging will stop once it exceeds the range. Short-circuit protection: refers to whether the load is short-circuited during the discharge or charging process of the battery pack, and whether the protection can be disconnected.

[0067] like Figures 4 to 8 As shown, they are respectively from Figure 2 The circuit diagram formed by dividing the overall circuit diagram, Figure 4 It is a voltage overcharge and over-discharge protection module. The AFE chip collects the voltage of a single battery pack in real time through resistor current limiting and capacitor filtering. The internal register has a settable value. The real-time collected data will be compared with this set value. The voltage overcharge protection means that the collected voltage is greater than the set overcharge voltage, and the voltage over-discharge protection means that the collected voltage is less than the over-discharge voltage. At this time, the AFE chip recognizes overcharge or over-discharge and takes corresponding actions.

[0068] Figure 5 It is a temperature protection module. The temperature protection module converts the temperature value into a voltage value through a thermistor. This value can be set inside the chip to set the temperature protection value. If this set value is exceeded, the chip will perform corresponding protection.

[0069] Figure 6 It is a current acquisition module. The current acquisition module adds resistance in the current loop, but the resistance value is very small, all in the MΩ level. The AFE chip also calculates the current by collecting the voltage on the loop resistance. And compare it with the chip's overcurrent, short-circuit protection and other parameters. If it is greater than the set parameters, the chip will also perform corresponding protection.

[0070] Figure 7 It is the discharge control module. Discharge control is the chip's management of the switch state of the MOS tube. Under normal circumstances, the MOS is in the open state. Under protection, the chip sends a shutdown signal. The circuit is mainly the circuit that drives the MOS.

[0071] The discharge control module in this embodiment includes a discharge driving unit and a discharge execution unit;

[0072] The discharge driving unit is used to provide a driving signal to the discharge execution device; the discharge execution unit is used to control the discharge and closing process; the discharge execution device in this embodiment quickly executes the discharge and closes the discharge operation under the control of the discharge driving unit.

[0073] The discharge driving unit comprises a first triode and a second triode; the emitters of the first triode and the second triode are connected and then connected to the discharge execution unit through a resistor; the base of the first triode is connected to the microcontroller chip through a resistor; the bases of the first triode and the second triode are connected and then respectively connected to the resistor connected in series to the collector through a resistor; that is, the bases of the first triode and the second triode are connected; the base of the first triode is connected to the resistor connected in series to the collector through a resistor; the base of the second triode is connected to the resistor connected in series to the collector through a resistor;

[0074] The discharge execution unit includes a plurality of parallel branches, each of which includes a MOS tube, the gate of which is connected to the discharge driving unit through a resistor; the source of the MOS tube is connected to the source of the MOS tubes of other branches; the drain of the MOS tube is connected to the drain of the MOS tubes of other branches and then connected to the charge execution unit;

[0075] Figure 8 The charging control module comprises a charging drive unit and a charging execution unit; the charging drive unit is used to provide a driving signal to the charging execution device; the charging execution unit is used to control the discharge and shutdown process; the discharge execution device in the present embodiment quickly performs the discharge and discharge shutdown operations under the control of the discharge drive unit.

[0076] The charging drive unit includes a third transistor, a fourth transistor, a first diode, and a second diode;

[0077] The base of the third triode is connected to the ground through a resistor; the emitter of the third triode is connected to the microcontroller chip; a resistor is connected between the base and emitter of the third triode; the collector of the third triode is connected to the positive electrode of the first diode, and the negative electrode of the first diode is connected to the positive electrode of the second diode; the negative electrode of the second diode is connected to the emitter of the fourth triode; the collector of the fourth triode is connected to the charging execution unit through a resistor; a resistor is connected between the base and collector of the fourth triode; the base of the fourth triode is connected to the negative electrode of the first diode;

[0078] The charging execution unit includes a plurality of parallel branches, each of which includes a MOS tube, the gate of which is connected to the cathode of the first diode of the charging driving unit through a resistor; the source of the MOS tube is connected to the source of the MOS tubes of other branches; the drain of the MOS tube is connected to the drain of the MOS tubes of other branches and then connected to the discharge execution unit;

[0079] The charging control is the chip's management of the switch state of the MOS tube. Under normal circumstances, the MOS is in the on state, and the chip sends a shutdown signal when there is protection.

[0080] Fig. 9 Power the chip and program burning port. The chip is powered by the battery. The real and fake capacitors are used for pure energy filtering, circuit current limiting protection, etc. Program burning is done through RS232, using the host computer operation, and a series of protection parameters can be configured.

[0081] Fig.10 For the short-circuit test circuit diagram, this embodiment also provides a test device constructed for a short-circuit protection circuit based on BMS, the test device includes a battery pack, a short-circuit protection circuit based on BMS, and an air switch;

[0082] One end of the short-circuit protection circuit is connected to the negative electrode of the battery pack, and the other end is connected to the positive electrode of the battery pack through an air switch;

[0083] The short-circuit test is carried out by the test device, and the waveform of the experimental record is recorded: the short-circuit test generally has the following important parameters: 1. The current generated by the main circuit during short circuit; 2. The protection shutdown time of the circuit during short circuit; 3. The surge voltage generated during short circuit;

[0084] The current generated by a battery short circuit is about 1000A.

[0085] The delay time of short circuit protection is about 460uS;

[0086] The surge voltage generated when the short circuit is turned off is about 90V.

[0087] The above-described embodiments are only preferred embodiments for fully illustrating the present utility model, and the protection scope of the present utility model is not limited thereto. Equivalent substitutions or changes made by technicians in the technical field on the basis of the present utility model are all within the protection scope of the present utility model. The protection scope of the present utility model shall be subject to the claims.

Claims

1. A short circuit protection circuit based on BMS, characterized in that: It includes a microcontroller chip, a discharge control module, a charge control module and a surge protection module. The microcontroller chip is connected to the discharge control module and the charge control module respectively. The discharge control module is used to control the discharge process of the battery. The charge control module is used to control the charge process of the battery. The surge protection module is connected to the discharge control module and the charge control module respectively to absorb surges when a short circuit occurs in the battery.

2. The short-circuit protection circuit based on BMS according to claim 1, characterized in that: It also includes a voltage overcharge protection module connected to the microcontroller chip; The voltage overcharge and over-protection module is used to collect the voltage of a single battery cell in real time, and block the input and output of the battery when the battery voltage is abnormal.

3. The short-circuit protection circuit based on BMS according to claim 1, characterized in that: Also included is a temperature protection module connected to the microcontroller chip; The temperature protection module is used to connect an external temperature resistor to collect the battery temperature and realize the temperature protection function.

4. The short-circuit protection circuit based on BMS according to claim 1, characterized in that: It also includes a current acquisition module connected to the microcontroller chip; The current acquisition module is used to acquire the current in real time.

5. The short-circuit protection circuit based on BMS according to claim 1, characterized in that: It also includes a chip power supply and a program burning port connected to the microcontroller chip; The chip power supply is used to provide power to the microcontroller chip; The program burning port is used to input external programs into the microcontroller chip.

6. The short-circuit protection circuit based on BMS according to claim 1, characterized in that: The surge protection module includes a diode group and a series capacitor group; One end of the diode group is connected to the source of the MOS field effect tube of the charging control module, and the other end is connected to the drain of the MOS field effect tube of the charging control module; the gate of the MOS field effect tube is connected to the temperature protection module through a resistor; One end of the series capacitor group is connected to the source of the MOS field effect tube of the charging control module, and the other end is connected to the source of the MOS field effect tube of the discharging control module; The drain of the MOS field effect tube of the charging control module is connected to the drain of the MOS field effect tube of the discharging control module.

7. The short-circuit protection circuit based on BMS according to claim 1, characterized in that: The discharge control module includes a discharge driving unit and a discharge execution unit; The discharge driving unit is used to provide a driving signal to the discharge execution device; the discharge execution unit is used to control the discharge and closing process; The discharge driving unit comprises a first triode and a second triode; the emitters of the first triode and the second triode are connected and then connected to the discharge execution unit through a resistor; the base of the first triode is connected to the microcontroller chip through a resistor; the bases of the first triode and the second triode are connected and then respectively connected to the resistor connected in series to the collector through a resistor; that is, the bases of the first triode and the second triode are connected; the base of the first triode is connected to the resistor connected in series to the collector through a resistor; the base of the second triode is connected to the resistor connected in series to the collector through a resistor; The discharge execution unit includes a plurality of parallel branches, each of which includes a MOS tube, a gate of which is connected to the discharge driving unit through a resistor; a source of the MOS tube is connected to the source of the MOS tubes of other branches; a drain of the MOS tube is connected to the drain of the MOS tubes of other branches and then connected to the charge execution unit.

8. The short-circuit protection circuit based on BMS according to claim 1, characterized in that: The charging control module includes a charging drive unit and a charging execution unit; the charging drive unit is used to provide a driving signal to the charging execution device; the charging execution unit is used to control the discharge and shutdown process; The charging drive unit includes a third transistor, a fourth transistor, a first diode, and a second diode; The base of the third triode is connected to the ground through a resistor; the emitter of the third triode is connected to the microcontroller chip; a resistor is connected between the base and emitter of the third triode; the collector of the third triode is connected to the positive electrode of the first diode, and the negative electrode of the first diode is connected to the positive electrode of the second diode; the negative electrode of the second diode is connected to the emitter of the fourth triode; the collector of the fourth triode is connected to the charging execution unit through a resistor; a resistor is connected between the base and collector of the fourth triode; the base of the fourth triode is connected to the negative electrode of the first diode; The charging execution unit includes a plurality of parallel branches, each of which includes a MOS tube, a gate of the MOS tube being connected to the cathode of the first diode of the charging driving unit through a resistor; a source of the MOS tube being connected to the source of the MOS tubes of other branches; and a drain of the MOS tube being connected to the drain of the MOS tubes of other branches and then connected to the discharge execution unit.

9. The test device is characterized by: The test device is constructed according to the BMS-based short-circuit protection circuit according to any one of claims 1 to 8, comprising a battery pack, a BMS-based short-circuit protection circuit, and an air switch; one end of the short-circuit protection circuit is connected to the negative electrode of the battery pack, and the other end is connected to the positive electrode of the battery pack through the air switch.

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