Battery protection board, battery and electric equipment

Abstract

The utility model provides a battery protection board, a battery and electric equipment. The battery protection board comprises a battery management chip and a current detection unit, the current detection unit is connected in series in a charging and discharging loop of the battery and is connected with the battery management chip; the current detection unit comprises a lead section, a temperature compensation element, a first resistor and a second resistor; the temperature compensation element is connected with the first resistor in parallel to form a first compensation branch, the first compensation branch is connected with the second resistor in series to form a second compensation branch, and the second compensation branch is connected with the wire section in parallel; wherein two ends of the first compensation branch are respectively connected with detection pins of the battery management chip, and the battery management chip is used for detecting the voltage drop of the first compensation branch. According to the utility model, the battery management chip is used for detecting the voltage drop of the first compensation branch, the detection object is changed, the temperature compensation capability of the formed current detection unit is relatively strong, an ideal compensation effect can be achieved, and the influence of temperature on the impedance of the lead section can be effectively relieved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery protection boards, in particular to a battery protection board, a battery and an electrical device. Background Art

[0002] At present, the battery protection board of lithium batteries mostly uses precision resistor detection to achieve overcurrent protection. When the lithium battery is connected to a load or charger, the current forms a voltage drop on the precision resistor. When the voltage drop is greater than or equal to the threshold set inside the battery protection board, the overcurrent protection is triggered. In order to reduce the temperature rise and meet the high current fast charging flow, multiple precision resistors are usually designed in parallel. This results in a large space occupied by the precision resistors, which is not conducive to the layout and wiring design of the battery protection board.

[0003] With the continuous improvement of battery technology, the battery protection boards of some lithium batteries directly use their own wires as current-sensing resistors, connect the battery management chip at both ends of the wires, and determine the current flowing through the battery when the load is connected based on the voltage drop at both ends of the wires. However, since the impedance of the wire is positively correlated with the temperature, as the temperature of the battery protection board increases during operation, the internal resistance of the wire will become larger and larger, seriously affecting the accuracy of the current detection results. For this reason, it is usually necessary to introduce negative temperature coefficient compensation electronic components into the circuit to reduce the impact of temperature on the impedance of the wire segment. However, due to the specification limitations of the negative temperature coefficient compensation electronic components, their compensation ability is often weak, and it is difficult to effectively eliminate the impact of temperature on the impedance of the wire segment, resulting in low accuracy of the current detection results and weak overcurrent protection capabilities of the battery protection board. Utility Model Content

[0004] In view of this, the utility model provides a battery protection board, a battery and an electrical device, so as to at least solve the problem that the temperature compensation capability of the existing battery protection board is weak, thus affecting the accuracy of the current detection result.

[0005] In order to achieve the above object, the technical solution of the utility model is implemented as follows:

[0006] The utility model provides a battery protection board, including a battery management chip and a current detection unit;

[0007] The current detection unit is connected in series in the charge and discharge circuit of the battery and is connected to the battery management chip;

[0008] The current detection unit includes a wire segment, a temperature compensation element, a first resistor and a second resistor;

[0009] The temperature compensation element is connected in parallel with the first resistor to form a first compensation branch, the first compensation branch is connected in series with the second resistor to form a second compensation branch, and the second compensation branch is connected in parallel with the wire segment;

[0010] Wherein, two ends of the first compensation branch are respectively connected to detection pins of the battery management chip, and the battery management chip is used to detect the voltage drop of the first compensation branch.

[0011] Optionally, the resistance of the wire segment is less than 5 mΩ, and the resistance of the temperature compensation element, the first resistor and the second resistor is greater than 100 Ω.

[0012] Optionally, the current detection unit further includes a third resistor;

[0013] The third resistor is disposed on the first compensation branch and is connected in series with the temperature compensation element.

[0014] Optionally, the temperature compensation element is a negative temperature coefficient thermistor.

[0015] Optionally, the conductor segment is an impedance-designed conductor segment.

[0016] Optionally, a circuit protection unit is also included;

[0017] The circuit protection unit is connected in series in the charge and discharge circuit of the battery and is connected to the battery management chip. The circuit protection unit is used to control the on and off of the charge and discharge circuit.

[0018] Optionally, the circuit protection unit includes two NPN MOS tubes, the gates of the two NPN MOS tubes are respectively connected to the battery management chip, the drains of the two NPN MOS tubes are connected to each other, and the sources of the two NPN MOS tubes are respectively connected to the charge and discharge circuit.

[0019] Optionally, a temperature detection unit is also included;

[0020] The temperature detection unit is connected to the current detection unit and is used to detect the operating temperature of the current detection unit.

[0021] The utility model also provides a battery, comprising a battery cell and a battery protection board as described in any one of the above items, wherein the battery protection board is electrically connected to the battery cell.

[0022] The utility model also provides an electrical device, comprising the above-mentioned battery.

[0023] Compared with the prior art, the battery protection board, battery and electrical equipment described in the utility model have the following advantages:

[0024] The battery protection board of the utility model includes a battery management chip and a current detection unit; the current detection unit is connected in series in the charge and discharge circuit of the battery and is connected to the battery management chip; the current detection unit includes a wire segment, a temperature compensation element, a first resistor and a second resistor; the temperature compensation element is connected in parallel with the first resistor to form a first compensation branch, the first compensation branch is connected in series with the second resistor to form a second compensation branch, and the second compensation branch is connected in parallel with the wire segment; wherein the two ends of the first compensation branch are respectively connected to the detection pins of the battery management chip, and the battery management chip is used to detect the voltage drop of the first compensation branch. Compared with the method of detecting the voltage drop at both ends of the conductive segment in the prior art, the utility model connects the detection pins of the battery management chip to the two ends of the first compensation branch formed by the temperature compensation element and the first resistor in parallel, respectively, for detecting the voltage drop of the first compensation branch, thus changing the detection object, and the temperature compensation capability of the formed current detection unit is relatively strong, and an ideal compensation effect can be achieved, which can effectively alleviate the influence of temperature on the impedance of the wire segment, and help to improve the accuracy of the current detection result.

[0025] The battery and electrical equipment of the present invention have the same or similar advantages as the prior art and the aforementioned battery protection board, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the accompanying drawings:

[0027] Figure 1 It is a circuit diagram of a battery protection board in the prior art;

[0028] Figure 2 It is a circuit diagram of a battery protection board in an embodiment of the utility model;

[0029] Figure 3 It is a circuit diagram of a current detection unit in an embodiment of the utility model;

[0030] Figure 4 It is a circuit diagram of another current detection unit in an embodiment of the utility model. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0032] The terms "first", "second", etc. in the specification and claims of the present utility model are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the utility model can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0033] It should be understood that the reference to "some embodiments" throughout the specification means that specific features, structures or characteristics related to the embodiments are included in at least one embodiment of the utility model. Therefore, the "in some embodiments" appearing in various places throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner.

[0034] In the prior art, in the circuit design of the lithium battery protection board, some battery protection boards use their own wires to act as current-sensing resistors, connect the battery management chip at both ends of the wires, and determine the current flowing through the battery when the load is connected based on the voltage drop at both ends of the wires. However, since the impedance of the wire is positively correlated with the temperature, as the temperature of the battery protection board increases during operation, the internal resistance of the wire will become larger and larger, seriously affecting the accuracy of the current detection results. For this reason, it is usually necessary to introduce negative temperature coefficient compensation electronic components into the circuit to reduce the impact of temperature on the impedance of the wire segment. Figure 1 A circuit diagram of a current detection part of a battery protection board in the prior art is shown. Figure 1 As shown, the wire segment R acts as a current-sense resistor, and the temperature compensation element RT1 is connected in parallel with the wire segment R. The internal resistance of the wire segment R (i.e., regarded as R) increases with the increase of the circuit operating temperature, and the internal resistance of the temperature compensation element RT1 (i.e., regarded as RT1) decreases with the increase of the circuit operating temperature. The increased internal resistance of the wire segment is regarded as ΔR, and the reduced internal resistance of the temperature compensation element RT1 is regarded as ΔRT1. Then, the total resistance Z formed by the temperature compensation element RT1 and the wire segment R in parallel satisfies the following formula ①:

[0035]

[0036] If it is assumed that the current flowing through the wire segment R and the temperature compensation element RT1 does not change, but the temperature rises, the internal resistance of the wire segment R and the internal resistance of the temperature compensation element RT1 will change after the temperature rises. To achieve the ideal compensation effect, the change in the internal resistance of the wire segment R and the change in the internal resistance of the temperature compensation element RT1 need to offset each other so that the total parallel resistance Z remains unchanged, that is, the above formula ① needs to satisfy the following formula ②:

[0037]

[0038] The above formula ② is converted by multiplying both sides by (R+□R) and (RT1-□RT1) to obtain the following formula ③:

[0039]

[0040] Therefore, if we want to achieve the ideal compensation effect and keep the total parallel resistance Z unchanged when the temperature changes, we need to satisfy the above formula ③;

[0041] However, in actual applications, the resistance of the wire segment R is in the milliohm level, usually less than 5mΩ, and the resistance of the temperature compensation element RT1 is in the hundred ohms or thousand ohms level, usually greater than 100Ω, that is, the resistance of the temperature compensation element RT1 is much greater than the resistance of the wire segment R, resulting in the above formula ③ not being established. Exemplarily, when the temperature is 25°C, the temperature compensation element RT1≈4kΩ, the wire segment R≈2mΩ, when the temperature is 40°C, the temperature compensation element RT1≈2kΩ, the wire segment R≈4mΩ, that is, ΔRT1≈2kΩ, ΔR≈2mΩ, substituting this value into the above formula ③, it is obvious that the equation cannot be established.

[0042] Therefore, in the prior art, when only the temperature compensation element RT1 is connected in parallel with the wire segment R, the compensation ability of the temperature compensation element RT1 is weak, and it is difficult to achieve an ideal compensation effect, thereby failing to effectively eliminate the influence of temperature on the impedance of the wire segment and failing to ensure the accuracy of the current detection result.

[0043] Based on this, the utility model provides a battery protection board, a battery and an electrical device, which can effectively improve the compensation capability of the temperature compensation element RT1, alleviate the influence of temperature on the impedance of the wire segment, and improve the accuracy of the current detection result. The utility model is described in detail below by listing specific embodiments.

[0044] Reference Figure 2 and Figure 3The battery protection board of the embodiment of the utility model includes a battery management chip U1 and a current detection unit; the current detection unit is connected in series in the charge and discharge circuit of the battery and is connected to the battery management chip U1; the current detection unit includes a wire segment R, a temperature compensation element RT1, a first resistor R1 and a second resistor R2; the temperature compensation element RT1 is connected in parallel with the first resistor R1 to form a first compensation branch, the first compensation branch is connected in series with the second resistor R2 to form a second compensation branch, and the second compensation branch is connected in parallel with the wire segment R; wherein the two ends of the first compensation branch are respectively connected to the detection pins of the battery management chip U1, and the battery management chip U1 is used to detect the voltage drop of the first compensation branch.

[0045] Specifically, the battery management chip U1 is used to monitor the voltage, current, temperature, etc. during the battery charging and discharging process in real time to avoid overcharging, over-discharging, overcurrent, etc. of the battery, so that the battery is in the best working state and the performance stability and service life of the battery are improved. When selecting the battery management chip U1, it is necessary to consider the comprehensive battery type, communication interface, functional requirements, parameter requirements, etc. For example, according to different battery types such as lithium-ion batteries or nickel-metal hydride batteries, the corresponding battery management chip U1 is selected, and according to the communication interface between the battery management chip U1 and the main control chip, such as I 2 C (Inter-Integrated Circuit, integrated circuit bus) interface, SPI (Serial Peripheral Interface, serial peripheral device) interface, etc., select an adaptive battery management chip U1, select a suitable battery management chip U1 according to the functions supported by the battery management chip U1, such as overcharge protection function, over-discharge protection function, overcurrent protection function, etc., and select a battery management chip U1 with a suitable threshold according to the battery system's requirements for parameters such as voltage accuracy and temperature range. This embodiment does not limit the specific selection of the battery management chip U1.

[0046] The current detection unit is connected in series in the battery charging and discharging circuit and is connected to the battery management chip U1. Figure 2 As shown in the dotted box, Figure 3 FIG. 4 shows an enlarged schematic diagram of the current detection unit. Figure 3As shown, the current detection unit includes a wire segment R, a temperature compensation element RT1, a first resistor R1 and a second resistor R2. The temperature compensation element RT1 is connected in parallel with the first resistor R1 to form a first compensation branch. The first compensation branch is connected in series with the second resistor R2 to form a second compensation branch. The second compensation branch is connected in parallel with the wire segment R. That is, the wire segment R can be regarded as being in parallel with the temperature compensation element RT1, the first resistor R1 and the second resistor R2, respectively, and the second resistor R2 can be regarded as being in series with the temperature compensation element RT1 and the first resistor R1, respectively. Among them, the two ends of the first compensation branch formed by the temperature compensation element RT1 and the first resistor R1 in parallel are respectively connected to the detection pins (such as Figure 2 The battery management chip U1 is connected to pin 1 and pin 2 in the figure, and is used to detect the voltage drop of the first compensation branch. Compared with the method in the prior art in which the detection pins of the battery management chip U1 are respectively connected to the two ends of the wire segment R for detecting the wire segment R, in this embodiment, the detection pins of the battery management chip U1 are respectively connected to the two ends of the first compensation branch for detecting the voltage drop of the first compensation branch, thereby changing the detection object.

[0047] If the voltage across the wire segment R is regarded as V1, and the current flowing through the wire segment R is regarded as I, then V1 = IR, and the voltage across the first compensation branch is regarded as V2, then V1 and V2 satisfy the following formula ④:

[0048]

[0049] Here, RTI|R1 means RTI in parallel with R1.

[0050] The internal resistance of the wire segment R increases with the increase of the circuit operating temperature, and the internal resistance of the temperature compensation element RT1 decreases with the increase of the circuit operating temperature. The increased internal resistance of the wire segment R is regarded as ΔR, and the reduced internal resistance of the temperature compensation element RT1 is regarded as ΔRT1. After the temperature increases, the internal resistance of the wire segment R and the internal resistance of the temperature compensation element RT1 both change. At this time, V1 and V2 satisfy the following formula ⑤:

[0051]

[0052] If it is assumed that the current flowing through the wire segment R and the temperature compensation element RT1 does not change, in order to achieve an ideal compensation effect, the voltage V2 at both ends of the first compensation branch connected to the detection pin of the battery management chip U1 should not change, that is, in an ideal state, when the current of the wire segment R and the temperature compensation element RT1 does not change, the voltage drop of the first compensation branch detected by the battery management chip U1 should remain unchanged, so that the above formula ④ and the above formula ⑤ are equal to each other, let a=RT1‖R1, b=(RT1-□RT1)‖R1, then the above formula ④ and the above formula ⑤ are converted to satisfy the following formula ⑥:

[0053]

[0054] After conversion, the following formula is finally obtained:

[0055]

[0056] Since the resistance values ​​of the temperature compensation element RT1, the first resistor R1 and the second resistor R2 are usually in the hundreds of ohms or thousands of ohms, the resistance values ​​on both sides of the above formula are of the same order of magnitude, which makes it easier for the equation to hold true. This shows that the first compensation branch and the second compensation branch of the battery protection board can effectively compensate for the wire segment R, effectively alleviate the influence of temperature on the impedance of the wire segment R, and improve the accuracy of the current detection results.

[0057] Of course, the first resistor R1 and the second resistor R2 can also play a certain role in voltage division. Since the internal resistance of the wire segment R and the internal resistance of the temperature compensation element RT1 are in an unstable state, as the temperature rises, the internal resistance of the wire segment R becomes larger and larger, and V1 becomes larger and larger. The existence of the second resistor R2 can share part of the voltage, so that the voltage at both ends of the first compensation branch is not too large. At the same time, when the internal resistance of the temperature compensation element RT1 approaches infinity, the current can flow through the first resistor R1 to ensure the integrity of the entire loop, thereby helping to ensure the reliability of the current detection unit.

[0058] In summary, the battery protection board of the utility model includes a battery management chip U1 and a current detection unit; the current detection unit is connected in series in the charge and discharge circuit of the battery and is connected to the battery management chip U1; the current detection unit includes a wire segment R, a temperature compensation element RT1, a first resistor R1 and a second resistor R2; the temperature compensation element RT1 is connected in parallel with the first resistor R1 to form a first compensation branch, the first compensation branch is connected in series with the second resistor R2 to form a second compensation branch, and the second compensation branch is connected in parallel with the wire segment R; wherein, the two ends of the first compensation branch are respectively connected to the detection pins of the battery management chip U1, and the battery management chip U1 is used to detect the voltage drop of the first compensation branch. Compared with the method of detecting the voltage drop at both ends of the conductive segment in the prior art, the utility model connects the detection pins of the battery management chip U1 to the two ends of the first compensation branch formed by the temperature compensation element RT1 and the first resistor R1 in parallel, respectively, for detecting the voltage drop of the first compensation branch, thus changing the detection object, and the temperature compensation capability of the formed current detection unit is relatively strong, and an ideal compensation effect can be achieved, which can effectively alleviate the influence of temperature on the impedance of the wire segment R, and help to improve the accuracy of the current detection result.

[0059] Optionally, refer to Figure 4, the current detection unit further includes a third resistor R3; the third resistor R3 is disposed on the first compensation branch and is connected in series with the temperature compensation element RT1.

[0060] Specifically, in some embodiments, the current detection unit further includes a third resistor R3, such as Figure 4 As shown, the third resistor R3 is arranged on the first compensation branch and is connected in series with the temperature compensation element RT1. The setting of the third resistor R3 can prevent the temperature compensation element RT1 from being short-circuited. When the temperature is too high, the resistance of the temperature compensation element RT1 gradually approaches infinitesimal. At this time, the impedance effect of the third resistor R3 can prevent the temperature compensation element RT1 from being short-circuited, thereby ensuring that the temperature compensation element RT1 can play a certain temperature compensation effect, which helps to improve the reliability and safety of the current inspection unit.

[0061] In the case where the third resistor R3 is also provided on the first compensation branch, the above formula ④ is correspondingly adjusted to the following formula ⑦:

[0062]

[0063] The above formula ⑤ is adjusted accordingly to the following formula ⑧:

[0064]

[0065] If it is assumed that the current flowing through the wire segment R and the temperature compensation element RT1 does not change, in order to achieve an ideal compensation effect, the voltage V2 at both ends of the first compensation branch connected to the detection pin of the battery management chip U1 should not change, that is, in an ideal state, when the current of the wire segment R and the temperature compensation element RT1 does not change, the voltage drop of the first compensation branch detected by the battery management chip U1 should remain unchanged, so that the above formula ⑦ and the above formula ⑧ are equal to each other, and c=(RT1+R3)‖R1, d=(RT1-ΔRT1+R3)‖R1, then the above formula ⑦ and the above formula ⑧ are converted to satisfy the following formula 9:

[0066]

[0067] After conversion, the following formula is finally obtained:

[0068]

[0069] Since the resistance of the third resistor R3 is also in the hundreds of ohms or thousands of ohms, the resistance values ​​on both sides of the above formula are of the same order of magnitude, which makes it easier for the equation to hold true. This shows that the first compensation branch and the second compensation branch of the battery protection board can effectively compensate for the wire segment R, effectively alleviate the influence of temperature on the impedance of the wire segment R, and improve the accuracy of the current detection results.

[0070] The first resistor R1, the second resistor R2 and the third resistor R3 can be selected as needed. For example, assuming that the current flowing through the wire segment R does not change, this embodiment uses a first resistor R1 with a resistance of 16KΩ, a second resistor R2 with a resistance of 4.5KΩ, and a third resistor R3 with a resistance of 6KΩ for verification:

[0071] When the temperature is -20℃, the internal resistance of the wire segment R is 3.28mΩ, the current I flowing through the wire segment R is 1A, V1=IR=3.28mV, and the temperature compensation element RT1 is infinite. Then the branch where the temperature compensation element RT1 and the third resistor R3 are located is considered to be open circuit, and the current only flows through the first resistor R1. The above formula ⑦ can be transformed into:

[0072]

[0073] Substituting the above data into the formula, we get V2 = 2.56mV;

[0074] When the temperature is 25℃, the internal resistance of the wire segment R is 4mΩ, the current I flowing through the wire segment R is 1A, V1=IR=4mV, the temperature compensation element RT1=10KΩ, substituting the above data into formula ⑦, we get V2=2.56mV;

[0075] When the temperature is 100°C, the internal resistance of the wire segment R is 5.2mΩ, the current I flowing through the wire segment R is 1A, V1=IR=5.2mV, and the temperature compensation element RT1=0KΩ, which is equivalent to the first resistor R1 and the third resistor R3 being connected in parallel. The above formula ⑦ can be transformed into:

[0076]

[0077] Substituting the above data into formula ⑦, we get V2 = 2.56mV.

[0078] It can be seen that if the current flowing through the wire segment R does not change, when the temperature changes, the voltage drop V2 of the first compensation branch detected by the battery management chip U1 remains unchanged, which means that the first compensation branch and the second compensation branch of the battery protection board can effectively compensate for the wire segment R, which can effectively alleviate the impact of temperature on the impedance of the wire segment R, and help to improve the accuracy of the current detection results.

[0079] Optionally, the temperature compensation element RT1 is a negative temperature coefficient thermistor.

[0080] Specifically, negative temperature coefficient thermistors, also known as NTC thermistors, have a resistance value that decreases as the temperature increases and are widely used in temperature measurement, temperature control, temperature compensation, and other aspects. Negative temperature coefficient thermistors are made of metal oxides such as manganese, cobalt, nickel, and copper as the main materials, and are manufactured using ceramic technology. These metal oxide materials have semiconductor properties and are similar to semiconductor materials such as germanium and silicon in terms of conductivity. When the temperature is low, the number of carriers in these oxide materials is small, so their resistance value is high. As the temperature rises, the number of carriers increases, and the resistance value decreases. The range of negative temperature coefficient thermistors at room temperature is 0.1 to 1000KΩ, and the temperature coefficient is -2% to -6.5%. Obviously, its resistance value varies greatly and can meet the application needs of various scenarios.

[0081] Optionally, the conductor segment R is an impedance-designed conductor segment.

[0082] Specifically, when the wire segment R is used as a current-sense resistor, the impedance design of the wire segment R can be performed. The purpose of the impedance design is to ensure that the effective transmission of signals, energy, etc. from the signal source to the load can be smoothly realized. In some embodiments, the impedance design of the wire segment R can be achieved by changing the impedance, specifically by adjusting the impedance value through the series and parallel connection of capacitors, inductors and loads. In some embodiments, the impedance design of the wire segment R can be achieved by adjusting the wavelength of the wire segment R, specifically by lengthening the distance between the source and the load, and adjusting the impedance to zero with the capacitor and inductor. After the impedance design of the wire segment R, the phenomenon of its internal resistance being too low can be avoided, thereby preventing the wire segment R from being short-circuited in the circuit structure.

[0083] Optionally, refer to Figure 2 The battery protection board also includes a circuit protection unit; the circuit protection unit is connected in series in the battery charging and discharging circuit and is connected to the battery management chip U1, and the circuit protection unit is used to control the conduction and shutdown of the charging and discharging circuit.

[0084] Specifically, the battery protection board also includes a circuit protection unit, such as Figure 2 As shown, the circuit protection unit is connected in series in the battery charging and discharging circuit and is connected to the battery management chip U1. The circuit protection unit is used to control the on and off of the battery charging and discharging circuit. In this embodiment, the circuit protection unit includes two NPN MOS tubes (such as Figure 2 The gates of the two MOS tubes are connected to the control pins of the battery management chip U1 (as shown in FIG. Figure 2The drains of the two MOS tubes are connected to each other to realize the series connection of the two MOS tubes, and the sources of the two MOS tubes are connected in series in the charge and discharge circuit of the battery. The two MOS tubes are in the on state when the voltage difference between the gate voltage and the source voltage is greater than the preset voltage difference, and are in the off state when the voltage difference between the gate voltage and the source voltage is less than or equal to the preset voltage difference. The preset voltage difference is determined according to the specifications of the MOS tube, and different MOS tubes may have different voltage differences required for conduction. In a specific implementation, the specifications of the MOS tube can be reasonably selected according to the overcurrent capacity of the battery protection board, etc., and this embodiment is not limited to this. Of course, in order to ensure the reliability of the circuit protection unit, the circuit protection unit may also include two capacitors (such as Figure 2 As shown in FIG. 1 and FIG. 2 , capacitor C1 and capacitor C2 are connected in series, capacitor C1 is connected to the source of MOS tube Q1, and capacitor C2 is connected to the source of MOS tube Q2, which can avoid sudden changes in voltage and current at the source and damage to the MOS tube.

[0085] Exemplarily, when the battery management chip U1 detects that the current flowing through the current detection unit is greater than its preset threshold, the battery management chip U1 will output a low level to the gates of the two MOS tubes, causing the voltage difference between the gate voltage and the source voltage of the two MOS tubes to be less than the preset voltage difference, thereby disconnecting the two MOS tubes. The disconnection of the two MOS tubes will put the entire charge and discharge loop in an open circuit state, thereby stopping the output of the battery to the load or the input of the charging device to the battery, thereby avoiding burning the load or the battery. Correspondingly, when the battery management chip U1 detects that the current flowing through the current detection unit does not exceed its preset threshold, the battery management chip U1 will output a high level to the gates of the two MOS tubes, causing the voltage difference between the gate voltage and the source voltage of the two MOS tubes to be greater than the preset voltage difference, thereby turning on the two MOS tubes, thereby ensuring the conduction of the entire charge and discharge loop. In the conduction state, the battery can smoothly output power to the load, and the charging device can also smoothly input power to the battery.

[0086] Optionally, the battery protection board further includes a temperature detection unit; the temperature detection unit is connected to the current detection unit and is used to detect the operating temperature of the current detection unit.

[0087] Specifically, the temperature detection unit is connected to the current detection unit and is used to detect the operating temperature of the wire segment R and the temperature compensation element RT1 in the current detection unit. Under normal circumstances, the temperature change of the wire segment R and the temperature compensation element RT1 has a corresponding reference table with the internal resistance change relationship. According to the temperature detected by the temperature detection unit, combined with the reference table, the internal resistance of the wire segment R and the temperature compensation element RT1 can be estimated, which is more conducive to personnel analyzing the current detection results. In some embodiments, the temperature detection unit may also include a prompt device, which can prompt the detected temperature, including but not limited to voice broadcast, text display, etc., which is not limited to this embodiment.

[0088] The utility model also provides a battery, comprising a battery cell and a battery protection board as described in any one of the above items, wherein the battery protection board is electrically connected to the battery cell.

[0089] Specifically, the battery includes a battery cell and any of the aforementioned battery protection boards. The battery protection board is electrically connected to the battery cell. The battery protection board can protect the battery cell during the charging and discharging process of the battery cell to avoid overcurrent, overdischarge, overcharging, etc., thereby ensuring the safe use of the battery.

[0090] The utility model also provides an electrical device, comprising the above-mentioned battery.

[0091] Specifically, the electrical equipment may be a battery pack, a charging station, etc., which has multiple batteries installed therein for providing power to the electric vehicle. The electrical equipment may also be a mobile terminal such as a mobile phone, a tablet computer, a laptop computer, etc., which has at least one battery installed therein for the user's daily entertainment and office use.

[0092] Finally, it should be noted that, in this article, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0093] In the several embodiments provided by the present utility model, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the connection between each other shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms. In addition, the functional units in the various embodiments of the present utility model can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery protection board, characterized in that: Including battery management chip and current detection unit; The current detection unit is connected in series in the charge and discharge circuit of the battery and is connected to the battery management chip; The current detection unit includes a wire segment, a temperature compensation element, a first resistor and a second resistor; The temperature compensation element is connected in parallel with the first resistor to form a first compensation branch, the first compensation branch is connected in series with the second resistor to form a second compensation branch, and the second compensation branch is connected in parallel with the wire segment; Wherein, two ends of the first compensation branch are respectively connected to detection pins of the battery management chip, and the battery management chip is used to detect the voltage drop of the first compensation branch.

2. The battery protection board according to claim 1, characterized in that: The resistance of the wire segment is less than 5 mΩ, and the resistance of the temperature compensation element, the first resistor and the second resistor are greater than 100 Ω.

3. The battery protection board according to claim 1, characterized in that: The current detection unit also includes a third resistor; The third resistor is disposed on the first compensation branch and is connected in series with the temperature compensation element.

4. The battery protection board according to claim 1, characterized in that: The temperature compensation element is a negative temperature coefficient thermistor.

5. The battery protection board according to claim 1, characterized in that: The conductor segment is an impedance-designed conductor segment.

6. The battery protection board according to claim 1, characterized in that: Also included is a circuit protection unit; The circuit protection unit is connected in series in the charge and discharge circuit of the battery and is connected to the battery management chip. The circuit protection unit is used to control the on and off of the charge and discharge circuit.

7. The battery protection board according to claim 6, characterized in that: The circuit protection unit includes two NPN MOS tubes, the gates of the two NPN MOS tubes are respectively connected to the battery management chip, the drains of the two NPN MOS tubes are connected to each other, and the sources of the two NPN MOS tubes are respectively connected to the charge and discharge circuit.

8. The battery protection board according to claim 1, characterized in that: Also includes a temperature detection unit; The temperature detection unit is connected to the current detection unit and is used to detect the operating temperature of the current detection unit.

9. A battery, characterized in that: It comprises a battery cell and a battery protection board as claimed in any one of claims 1 to 8, wherein the battery protection board is electrically connected to the battery cell.

10. An electrical device, characterized in that: A battery comprising the battery of claim 9.

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