Battery protection board and charging and discharging method thereof

Abstract

The present invention belongs to the technical field of battery protection boards, specifically a battery protection board and a charging and discharging method thereof, comprising: an aluminum substrate and a circuit board disposed therebetween; the aluminum substrate comprising an aluminum plate, a MOS tube and a charge-discharge current sampling resistor distributed in the middle of the aluminum plate, a first assembly hole provided on the aluminum plate, a hollow column disposed above the first assembly hole, a connection hole provided on the aluminum plate, and a pin passing through the connection hole and connected to the MOS tube and the charge-discharge current sampling resistor and the circuit board; the circuit board comprising a base plate, a second assembly hole provided on the base plate and corresponding to the first assembly hole, and a connection position disposed on the base plate. The battery protection board adds overvoltage and overcurrent discharge functions to the original battery protection board functions (overcharge, overdischarge, balancing, and output short circuit), greatly improving the reliability of the lithium battery, reducing the risk of lithium battery explosion, and simultaneously reducing the failure rate of the battery protection board and motor controller.

Description

Technical Field

[0001] The present invention relates to the technical field of battery protection boards, and in particular to a battery protection board and a charging and discharging method thereof. Background Art

[0002] Lithium and sodium batteries must not be overcharged when fully charged. However, when powered by motors in vehicles like electric vehicles and forklifts, the motors require braking or energy recovery during high-speed operation to increase the vehicle's range. During this time, the motor's rotational potential energy is converted into electrical energy by the motor controller to recharge the battery. However, when the battery charge level drops below full and cannot effectively absorb the returned energy, the battery management system (BMS) automatically shuts down the charging circuit. The motor's rotational potential energy cannot be dissipated, but instead is converted into a higher voltage, releasing it until it breaks down the MOSFET in the motor controller or the MOSFET in the battery management system, ultimately damaging the motor controller or the battery management system.

[0003] When an electric vehicle switches from high-speed operation to braking, the high energy generated is converted into electrical energy and then recharged back into the battery. Because braking power is significantly greater than the motor's operating power (just like in a car, starting acceleration is lower than braking acceleration, and in the energy recovery system, the reverse charging current is greater than the normal driving current), and because the battery's current absorption capacity is limited, the excess energy absorbed by the battery can affect battery safety and service life. Furthermore, traditional battery protection boards are typically integrated onto double-sided circuit boards and then protected by an aluminum casing. However, this often results in increased circuit board temperature and difficulty dissipating heat, compromising the battery panel's protective function.

[0004] The present invention converts the electrical energy exceeding the amount absorbed by the battery into heat energy through a discharge resistor and releases the heat energy to protect the motor controller and the battery protection board. Summary of the Invention

[0005] The present invention aims to solve one of the technical problems existing in the prior art or related technologies.

[0006] To this end, the technical solution adopted in the present invention is:

[0007] A battery protection board comprises: an aluminum substrate and a circuit board arranged therebetween; the aluminum substrate comprises an aluminum plate, a MOS transistor and a charge-discharge current sampling resistor distributed in the middle of the aluminum plate, a first assembly hole provided in the aluminum plate, a hollow column provided above the first assembly hole, a connection hole provided in the aluminum plate, and a pin passing through the connection hole and connected to the MOS transistor, the charge-discharge current sampling resistor, and the circuit board; wherein the MOS transistors are arranged in pairs in opposite directions, and the MOS transistors are distributed in parallel in the middle of the aluminum plate, and the charge-discharge current sampling resistor is arranged on the side of the MOS transistor; the circuit board comprises a base plate, a second assembly hole provided in the base plate and corresponding to the first assembly hole, and a connection position provided on the base plate.

[0008] In a preferred example, the present invention can be further configured as follows: the aluminum substrate further includes positioning posts fixed on the aluminum plate.

[0009] In a preferred example, the present invention can be further configured as follows: a reinforcing rib located on one side of the assembly hole is installed on the outer side of the aluminum plate, and an assembly hole 1 is correspondingly opened on the reinforcing rib.

[0010] In a preferred example, the present invention can be further configured as follows: the substrate also includes a main control single chip, a battery balancing and voltage detection circuit, a discharge MOS drive circuit, a charge MOS drive circuit, a charge and discharge amplification and overcurrent detection circuit, a discharge resistor drive circuit, a battery pack voltage detection circuit, a charging switch tube, a discharge switch tube, a discharge resistor switch tube and a high-power discharge resistor.

[0011] In a preferred embodiment, the present invention can be further configured to include the following charging method:

[0012] The positive pole of the charger is connected to the positive pole of the battery, and the negative pole of the battery is connected to the positive and negative poles of the battery pack through the charge and discharge current sampling resistor, the charging switch tube, and the discharge switch tube to form a charging circuit;

[0013] The main control chip monitors whether the battery voltage is normal during charging through the battery balancing and voltage detection circuit. If the battery voltage exceeds the maximum charging voltage, the microcontroller will turn off the charging switch tube to stop charging;

[0014] The main control chip uses the battery balancing and voltage detection circuits to monitor whether there are any differences in the voltage of each small battery cell during charging. If there are any differences, the main control chip uses the battery balancing and voltage detection circuits to control the current size of each single battery to ensure that the voltage of each battery is balanced.

[0015] In a preferred embodiment, the present invention can be further configured to include the following discharge method:

[0016] The current from the battery to the positive electrode of the battery pack flows to the power-consuming device, returns to the negative electrode of the battery pack, the discharge switch tube, the charge switch tube and the charge and discharge current sampling resistor, and finally returns to the negative electrode of the battery;

[0017] The main control chip monitors whether the battery voltage is normal during discharge through battery balancing and voltage detection circuits. If the battery is undervoltage, the microcontroller will turn off the discharge switch tube to stop discharging.

[0018] In a preferred embodiment, the present invention can be further configured to discharge and heat the battery pack when the battery pack exceeds the minimum charge and discharge temperature of the battery; the discharge switch tube does not operate during normal temperature discharge; during energy recovery, when the current passes through the charge and discharge sampling resistor, the current signal is transmitted to the charge and discharge amplification and overcurrent detection circuit; when the maximum charge current allowed by the battery is reached, the single-chip microcomputer outputs a discharge switch signal, which opens the discharge resistor switch tube through the discharge resistor drive circuit, and the reverse current passes through the positive electrode of the battery pack, the discharge resistor, the discharge resistor switch tube, and the negative electrode of the battery pack, thereby shunting the reverse charging current to protect the battery;

[0019] The total charging current of reverse charging = battery charging current + high-power discharge resistor current.

[0020] In a preferred example, the present invention can be further configured as follows: when the battery power is lower than full charge, the voltage between the positive and negative electrodes of the battery pack is monitored by the battery pack voltage detection circuit during energy recovery. When the voltage is lower than the maximum charging voltage of the battery, the discharge resistor switch tube is turned on to shunt the energy recovery current to release the protection battery protection board.

[0021] In a preferred example, the present invention can be further configured as follows: the high-power discharge resistor is mounted on an aluminum substrate or serves as an external discharge resistor.

[0022] In a preferred embodiment, the present invention can be further configured as follows: the discharge resistor driving circuit, the high-power discharge resistor, and the discharge resistor switch tube constitute a discharge switch circuit, and the discharge current of the discharge switch circuit is adjusted by the conduction ratio of the discharge PWM to adjust the discharge resistor from fully closed to fully conductive;

[0023] When the charging current is lower than the maximum charging current of the battery: the discharge PWM starts to conduct, always keeping the charging current lower than the maximum current that the battery can receive, and discharging the part that exceeds the maximum current;

[0024] When the charging voltage is lower than the maximum charging battery voltage: the discharge PWM starts to turn on, and the reverse charging voltage is controlled by the discharge PWM on-time to stabilize the voltage to be lower than the maximum charging voltage.

[0025] The above technical solution of the present invention has the following beneficial technical effects:

[0026] 1. The present invention uses a battery protection board to add overvoltage and overcurrent discharge functions on the basis of the original battery protection board functions (overcharge, overdischarge, balancing, and output short circuit), greatly improving the reliability of lithium batteries, reducing the risk of lithium battery explosion, and reducing the failure rate of the battery protection board and motor controller.

[0027] 2. The present invention places the MOS tube and the charge-discharge current sampling resistor on an aluminum substrate and reconnects them to the substrate using pins. During operation, part of the electricity is transferred to the MOS tube and the charge-discharge current sampling resistor to generate heat and release, while part of the electricity is transferred to the aluminum plate to dissipate heat, thereby greatly improving the discharge efficiency. This is not only conducive to the safe release of excess electricity, but also achieves better heat dissipation, ensuring safe and efficient operation of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic structural diagram of an aluminum substrate according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the assembly of a battery protection board according to an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the circuit board structure according to an embodiment of the present invention;

[0031] Figure 4 The figure is a schematic diagram of a circuit board according to an embodiment of the present invention.

[0032] Reference numerals:

[0033] 100, aluminum substrate; 110, aluminum plate; 120, MOS tube; 130, charge and discharge current sampling resistor; 140, assembly hole 1; 150, hollow column; 160, connection hole; 170, pin; 180, positioning column; 190, reinforcement rib;

[0034] 200, circuit board; 210, base plate; 220, second assembly hole; 230, connection position. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be noted that the embodiments of the present invention and the features therein can be combined with each other without conflict.

[0036] A battery protection board and a charging and discharging method thereof provided by some embodiments of the present invention are described below with reference to the accompanying drawings.

[0037] Combine Figures 1-4As shown, the present invention provides a battery protection board and a charging and discharging method thereof, comprising: an aluminum substrate 100 and a circuit board 200 arranged therebetween.

[0038] Among them, the aluminum substrate 100 includes an aluminum plate 110, a MOS tube 120 and a charge-discharge current sampling resistor 130 distributed in the middle of the aluminum plate 110, an assembly hole 140 opened on the aluminum plate 110, a hollow column 150 set on the assembly hole 140, a connection hole 160 opened on the aluminum plate 110, and a pin 170 passing through the connection hole 160 and connected between the MOS tube 120 and the charge-discharge current sampling resistor 130 and the circuit board 200; the circuit board 200 includes a substrate 210, an assembly hole 220 opened on the substrate 210 and corresponding to the assembly hole 140, and a connection position 230 set on the substrate 210.

[0039] The pin 170 passes through the connection hole 160 and is connected to the connection position 230 , and is connected by welding to serve as a signal connection.

[0040] Furthermore, the aluminum substrate 100 also includes a positioning column 180 fixed on the aluminum plate 110. The arrangement of the positioning column 180 can improve the structural strength of the aluminum substrate 100 and the circuit board 200 after assembly, thereby ensuring the stability of the battery protection board.

[0041] On the other hand, a reinforcing rib 190 is installed on the outer side of the aluminum plate 110 and is located on the side of the assembly hole 140, and an assembly hole 140 is correspondingly opened on the reinforcing rib 190. By passing assembly parts such as bolts through the assembly hole 140, the upper and lower aluminum substrates 100 and the middle group of circuit boards 200 can be assembled together, and at the same time, the reinforcing rib 190 is passed through to further improve the overall stability.

[0042] like Figure 1 As shown, the MOS tubes 120 are arranged in groups of two facing each other, and the MOS tubes 120 are distributed in parallel in the middle of the aluminum plate 110. The charge and discharge current sampling resistors 130 are arranged in groups of two on the side of the MOS tubes 120, and the MOS tubes 120 are connected head to head in groups of two.

[0043] It should be noted that the substrate 210 also includes a main control chip, a battery balancing and voltage detection circuit, a charge and discharge amplification and overcurrent detection circuit, three sets of discharge resistor drive circuits, a battery pack voltage detection circuit, a charging switch tube, a discharge switch tube, a discharge resistor switch tube and a high-power discharge resistor.

[0044] Specifically, the battery protection board includes the following charging methods:

[0045] The positive electrode of the charger is connected to the positive electrode of the battery, and the negative electrode of the battery is connected to the positive and negative electrodes of the battery pack through the charge and discharge current sampling resistor 130, the charging switch tube, and the discharge switch tube to form a charging circuit;

[0046] The main control chip monitors whether the battery voltage is normal during charging through the battery balancing and voltage detection circuit. If the battery voltage exceeds the maximum charging voltage, the microcontroller will turn off the charging switch tube to stop charging;

[0047] The main control chip uses the battery balancing and voltage detection circuits to monitor whether there are any differences in the voltage of each small battery cell during charging. If there are any differences, the main control chip uses the battery balancing and voltage detection circuits to control the current size of each single battery to ensure that the voltage of each battery is balanced.

[0048] Specifically, the battery protection board includes the following discharge methods:

[0049] The current flows from the battery to the positive electrode of the battery pack, to the power-consuming device, back to the negative electrode of the battery pack, the discharge switch tube, the charge switch tube and the charge and discharge current sampling resistor 130, and finally back to the negative electrode of the battery;

[0050] The main control chip monitors whether the battery voltage is normal during discharge through battery balancing and voltage detection circuits. If the battery is undervoltage, the microcontroller will turn off the discharge switch tube to stop discharging.

[0051] During the above-mentioned charge and discharge operation, the battery pack is discharged and heated when it exceeds the minimum charge and discharge temperature of the battery; the discharge switch tube does not work during discharge at room temperature, and during energy recovery, the current passes through the charge and discharge sampling resistor and transmits the current signal to the charge and discharge amplification and overcurrent detection circuit. When the maximum charge current allowed by the battery is reached, the microcontroller outputs a discharge switch signal, which opens the discharge resistor switch tube through the discharge resistor drive circuit, and the reverse current passes through the positive electrode of the battery pack, the discharge resistor, the discharge resistor switch tube, and the negative electrode of the battery pack, thereby shunting the reverse charging current to protect the battery;

[0052] Among them, the total charging current diverted by the reverse charging current = battery charging current + high-power discharge resistor current.

[0053] Furthermore, when the battery power is lower than full charge, the voltage between the positive and negative electrodes of the battery pack is monitored by the battery pack voltage detection circuit during energy recovery. When the voltage is lower than the maximum charging voltage of the battery, the discharge resistor switch tube is turned on to shunt the energy recovery current to release the protection battery protection board.

[0054] On the other hand, the high-power discharge resistor is an external discharge resistor. This type of resistor has low power and can be set on an aluminum substrate or a circuit board. If it has high power, it can be connected to other parts for better heat dissipation.

[0055] Specifically, the discharge resistor driving circuit, the high-power discharge resistor and the discharge resistor switch tube constitute a discharge switch circuit. The discharge current of the discharge switch circuit is adjusted by the conduction ratio of the discharge PWM to adjust the discharge resistor from fully closed to fully conductive.

[0056] When the charging current is lower than the maximum charging current of the battery: the discharge PWM starts to conduct, always keeping the charging current lower than the maximum current that the battery can receive, and discharging the part that exceeds the maximum current;

[0057] When the charging voltage is lower than the maximum charging battery voltage: the discharge PWM starts to turn on, and the reverse charging voltage is controlled by the discharge PWM on-time to stabilize the voltage below the maximum charging voltage. When the on-time becomes longer, the shunt current becomes larger and the reverse charging voltage is stabilized, and vice versa.

[0058] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and alterations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A battery protection board, characterized in that: include: an aluminum substrate (100) and a circuit board (200) disposed therebetween; The aluminum substrate (100) comprises an aluminum plate (110), a MOS tube (120) and a charge-discharge current sampling resistor (130) distributed in the middle of the aluminum plate (110), an assembly hole (140) provided on the aluminum plate (110), a hollow column (150) provided on the assembly hole (140), a connection hole (160) provided on the aluminum plate (110), and a pin (170) passing through the connection hole (160) and connected between the MOS tube (120) and the charge-discharge current sampling resistor (130) and the circuit board (200); The two MOS tubes (120) are arranged in opposite directions as a group, and the MOS tubes (120) are distributed in parallel in the middle of the aluminum plate (110), and the charge and discharge current sampling resistor (130) is arranged on the side of the MOS tube (120); The circuit board (200) comprises a base plate (210), a second assembly hole (220) provided on the base plate (210) and corresponding to the first assembly hole (140), and a connection position (230) provided on the base plate (210); The substrate (210) also includes a main control chip, a battery balancing and voltage detection circuit, a discharge MOS drive circuit, a charge MOS drive circuit, a charge and discharge amplification and overcurrent detection circuit, a discharge resistor drive circuit, a battery pack voltage detection circuit, a charge switch tube, a discharge switch tube, a discharge resistor switch tube, and a high-power discharge resistor.

2. A battery protection board according to claim 1, characterized in that: The aluminum substrate (100) further includes a positioning column (180) fixed on the aluminum plate (110).

3. The battery protection board according to claim 1, characterized in that: A reinforcing rib (190) located on one side of the first assembly hole (140) is installed on the outer side of the aluminum plate (110), and the first assembly hole (140) is correspondingly opened on the reinforcing rib (190).

4. The battery protection board according to claim 1, characterized in that: The high-power discharge resistor is mounted on an aluminum substrate or serves as an external discharge resistor.

5. A charging and discharging method for a battery protection board according to any one of claims 1 to 4, characterized in that: The charging method is as follows: The positive electrode of the charger is connected to the positive electrode of the battery, and the negative electrode of the battery is connected to the positive and negative electrodes of the battery pack through the charge and discharge current sampling resistor (130), the charging switch tube, and the discharge switch tube to form a charging circuit; The main control chip monitors whether the battery voltage is normal during charging through the battery balancing and voltage detection circuit. If the battery voltage exceeds the maximum charging voltage, the microcontroller will turn off the charging switch tube to stop charging; The main control chip uses the battery balancing and voltage detection circuits to monitor whether there are any differences in the voltage of each small battery cell during charging. If there are any differences, the main control chip uses the battery balancing and voltage detection circuits to control the current size of each single battery to ensure the voltage of each battery is balanced. The discharge method is as follows: The battery is connected to the positive electrode of the battery pack, flows to the electrical device, returns to the negative electrode of the battery pack, the discharge switch tube, the charge switch tube and the charge and discharge current sampling resistor (130), and finally returns to the negative electrode of the battery; The main control chip monitors whether the battery voltage is normal during discharge through battery balancing and voltage detection circuits. If the battery is undervoltage, the microcontroller will turn off the discharge switch tube to stop discharging.

6. The charging and discharging method of the battery protection board according to claim 5, characterized in that: When the battery pack exceeds the minimum charge and discharge temperature, it discharges and heats the battery pack. When discharging at room temperature, the discharge switch tube does not work. During energy recovery, the current passes through the charge and discharge sampling resistor and transmits the current signal to the charge and discharge amplification and overcurrent detection circuit. When the maximum charge current allowed by the battery is reached, the microcontroller outputs a discharge switch signal, which opens the discharge resistor switch tube through the discharge resistor drive circuit. The reverse current passes through the positive electrode of the battery pack, the discharge resistor, the discharge resistor switch tube, and the negative electrode of the battery pack, thereby shunting the reverse charging current to protect the battery. The total charging current of reverse charging = battery charging current + high-power discharge resistor current.

7. The charging and discharging method of the battery protection board according to claim 5, characterized in that: When the battery power is lower than full charge, the voltage between the positive and negative electrodes of the battery pack is monitored by the battery pack voltage detection circuit during energy recovery. When the voltage is lower than the maximum charging voltage of the battery, the discharge resistor switch tube is turned on to shunt the energy recovery current to release the protection battery protection board.

8. The charging and discharging method of the battery protection board according to claim 5, characterized in that: The discharge resistor driving circuit, the high-power discharge resistor and the discharge resistor switch tube form a discharge switch circuit. The discharge current of the discharge switch circuit is adjusted by the conduction ratio of the discharge PWM to adjust the discharge resistor from fully closed to fully conductive. When the charging current is lower than the maximum charging current of the battery: the discharge PWM starts to conduct, always keeping the charging current lower than the maximum current that the battery can receive, and discharging the part that exceeds the maximum current; When the charging voltage is lower than the maximum charging battery voltage: the discharge PWM starts to turn on, and the reverse charging voltage is controlled by the discharge PWM on-time to stabilize the voltage to be lower than the maximum charging voltage.

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