A battery pack leakage detection circuit

Abstract

The utility model provides a kind of battery pack electric leakage detection circuit, comprising: power supply circuit, negative pressure generating circuit, micro-current detection circuit;The signal output end of micro-current detection circuit is connected to the connecting resistance both ends of series battery pack middle pole and lithium battery protection chip;By collecting the signal output by micro-current acquisition circuit and converting into current absolute value, compare current absolute value with preset value to determine whether leakage occurs;The power supply circuit and negative voltage generating circuit are respectively used to generate positive voltage power supply and negative voltage power supply for the micro-current detection circuit;The power supply circuit also powers the negative pressure generating circuit.

Description

Technical Field

[0001] This utility model relates to battery packs, and more particularly to a battery pack leakage detection circuit. Background Technology

[0002] Lithium-ion batteries are a type of battery that uses lithium metal or lithium alloys as the positive / negative electrode materials and a non-aqueous electrolyte solution. Due to the highly reactive chemical properties of lithium metal, its processing, storage, and use require very strict environmental control.

[0003] However, with the development of science and technology, lithium batteries have become the mainstream. Lithium batteries can be broadly divided into two categories: lithium metal batteries and lithium-ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable.

[0004] Existing lithium batteries all have internal circuitry within the cell, which can cause signal interference to devices during use. To shield against this interference, most manufacturers encapsulate the cell with conductive cloth. However, most of these encapsulation processes do not perform short-circuit testing between the conductive cloth and the positive and negative terminals of the cell. If a short circuit occurs between the conductive cloth and the cell, it can lead to casing corrosion and affect the cell's lifespan. Utility Model Content

[0005] The main technical problem to be solved by this utility model is to provide a battery pack leakage detection circuit that can detect both forward and reverse leakage.

[0006] To solve the above-mentioned technical problems, this utility model provides a battery pack leakage detection circuit, including: a power supply circuit, a negative voltage generation circuit, and a micro current detection circuit.

[0007] The signal output terminal of the micro-current detection circuit is connected to the two ends of the connection resistor between the intermediate electrode of the series battery pack and the lithium battery protection chip; by acquiring the signal output by the micro-current acquisition circuit and converting it into an absolute current value, the absolute current value is compared with a preset value to determine whether leakage has occurred.

[0008] The power supply circuit and the negative voltage generating circuit are used to generate positive voltage and negative voltage power to the micro current detection circuit, respectively; the power supply circuit also supplies power to the negative voltage generating circuit.

[0009] In a preferred embodiment: the microcurrent detection circuit includes a differential amplifier circuit composed of operational amplifier U1 and peripheral circuits, used to differentially amplify and output the voltage signal generated across the resistor.

[0010] In a preferred embodiment: the microcurrent detection circuit further includes a voltage selection module, which is used to select positive voltage and negative voltage to power the operational amplifier U1, or to power the operational amplifier U1 only with positive voltage.

[0011] In a preferred embodiment: the voltage selection module includes 0-ohm resistors JR1 and JR2, the other end of JR1 is connected to the negative voltage generated by the negative voltage generating circuit, and the other end of JR2 is connected to GND and capacitor C16, the other end of C16 is connected to the negative voltage generated by the negative voltage generating circuit;

[0012] Pin 4 of the operational amplifier U1 in the micro-current detection circuit is connected to the 0-ohm resistors JR1 and JR2. When JR1 is selected, the operational amplifier U1 is powered by both positive and negative voltages, supporting the input and output of positive and negative voltage signals. When JR2 is selected, the operational amplifier U1 is powered only by positive voltage, supporting the input and output of positive voltage signals.

[0013] In a preferred embodiment: pin 3 of the operational amplifier U1 is connected to resistors R1 and RF1 respectively, the other end of resistor R1 is the positive input of the micro-current detection circuit, and the other end of resistor RF1 is connected to GND; one end of resistor R2 is connected to the negative input of the micro-current detection circuit, and the other end is connected to pin 2 of the operational amplifier U1, resistor RF2 and capacitor C1, and the other end of the connection between RF2 and C1 is connected to pin 1 of the operational amplifier U1.

[0014] In a preferred embodiment: pin 1 of the operational amplifier U1 is connected to R11, and the other end of R11 is connected to pin 5 of the operational amplifier U1 and C7 respectively; pin 5 and pin 7 of the operational amplifier U1 are connected to resistor R12, and the other end of resistor R12 is connected to C8 and J2 to output voltage signals; pin 8 of the operational amplifier U1 is connected to the positive voltage generated by the power supply circuit and capacitor C15.

[0015] In a preferred embodiment: the negative voltage generating circuit includes a chip U5, whose pins 4 and 8 are connected to the positive voltage generated by the power supply circuit, pin 1 is connected to GND, pin 5 is connected to capacitor C24, pins 2 and 6 are connected to capacitor C30 and resistor R21, pin 7 is connected to resistors R20 and R21 respectively, the other end of R20 is connected to power supply 15V, the other end of R21 is connected to pin 6 of chip U5 and capacitor C30, and pin 3 is connected to the positive terminal of capacitor CE3;

[0016] The negative terminal of capacitor CE3 is connected to the negative terminal of diode D1 and the positive terminal of diode D2, respectively; the positive terminal of diode D1 is connected to the negative terminal of capacitor CE4, and the negative terminal of diode D2 is connected to GND.

[0017] The chip U5 outputs a square wave voltage at pin 3. When the output is high, capacitor CE3 is charged through diode D2. When the output is low, capacitor CE3 is discharged through diode D1 and capacitor CE4, and capacitor CE4 is charged.

[0018] In a preferred embodiment: the power supply circuit selects a 15V DC power strip J1 as the input, and two pins of the power strip J1 are connected to GND; one pin of the power strip J1 is connected to an inductor L1, and the other end of the inductor L1 is connected to the positive terminals of capacitors C1E and C28 to form an LC filter circuit; the positive terminal of capacitor C28 is connected to the positive terminal of diode D3, and the negative terminal of D3 is connected to the positive terminals of capacitors CE2, C27 and C23 to form the positive voltage output terminal of the power supply circuit.

[0019] In a preferred embodiment: the power supply circuit selects the highest output voltage of the battery pack itself and inputs it through the positive terminal of diode D4.

[0020] In a preferred embodiment: the microcurrent detection circuit is one or more channels, and when the microcurrent detection circuit is multiple channels, the circuit structure of each microcurrent detection circuit is the same.

[0021] Compared with the prior art, the technical solution of this utility model has the following beneficial effects:

[0022] This invention provides a battery pack leakage detection circuit. A negative voltage generation circuit generates a negative voltage, allowing the power supply circuit and the negative voltage generation circuit to provide positive and negative voltages respectively to the micro-current detection circuit. This enables the battery pack leakage detection circuit to detect both forward and reverse leakage. Furthermore, to prevent the downstream device used to collect the output of the micro-current detection circuit from not supporting negative voltage input, a voltage selection module is used to ensure that only the power supply circuit provides a positive voltage to the micro-current detection circuit, allowing the micro-current detection circuit to detect only forward leakage. Attached Figure Description

[0023] Figure 1 This is a block diagram showing a preferred embodiment of the present invention.

[0024] Figure 2 This is a circuit diagram of the power supply circuit in a preferred embodiment of the present invention;

[0025] Figure 3 This is a circuit diagram of the negative pressure generating circuit in a preferred embodiment of the present invention;

[0026] Figure 4 This is a circuit diagram of the microcurrent detection circuit in a preferred embodiment of the present invention. Detailed Implementation

[0027] To make the technical solution and features of this utility model clearer, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only for illustrating this utility model and are not intended to limit the scope of this utility model. After reading this utility model, any modifications of this utility model by those skilled in the art in various equivalent forms fall within the scope defined by the appended claims.

[0028] refer to Figures 1-4 This embodiment provides a battery pack leakage detection circuit, including: a power supply circuit, a negative voltage generation circuit, and a micro current detection circuit;

[0029] The signal output terminal of the micro-current detection circuit is connected to the two ends of the connection resistor between the intermediate electrode of the series battery pack and the lithium battery protection chip; by acquiring the signal output by the micro-current acquisition circuit and converting it into an absolute current value, the absolute current value is compared with a preset value to determine whether leakage has occurred.

[0030] The power supply circuit supplies power to the negative voltage generating circuit, causing the negative voltage generating circuit to produce a negative voltage. Combined with the positive voltage generated by the power supply circuit, the positive and negative voltages can be used to power the micro-current detection circuit respectively. This allows the micro-current detection circuit to detect either forward or directional leakage current.

[0031] In this embodiment, the microcurrent detection circuit may be one or more channels. When there are multiple channels, the circuit structure of each channel is identical. For ease of explanation, the following description focuses on the specific circuit structure of one channel of the microcurrent detection circuit.

[0032] The device for acquiring the output signal of the micro-current acquisition circuit can be a voltmeter or an MCU acquisition circuit. Since some MCU acquisition circuits do not support negative voltage input, the battery pack leakage detection circuit in this embodiment can also detect only positive leakage. To facilitate switching between detecting positive and reverse leakage, or only positive leakage, the micro-current detection circuit also includes a voltage selection module. This module is used to select whether to power the operational amplifier U1 with positive or negative voltage, or only with positive voltage. This allows for switching between micro-current detection leakage modes.

[0033] Specifically, the voltage selection module includes 0-ohm resistors JR1 and JR2. The other end of JR1 is connected to the negative voltage generated by the negative voltage generating circuit, and the other end of JR2 is connected to GND and capacitor C16. The other end of C16 is connected to the negative voltage generated by the negative voltage generating circuit. In this embodiment, the negative voltage is -15V.

[0034] Pin 4 of the operational amplifier U1 in the micro-current detection circuit is connected to the 0-ohm resistors JR1 and JR2. When JR1 is selected, the operational amplifier U1 is powered by both positive and negative voltages, supporting the input and output of positive and negative voltage signals. When JR2 is selected, the operational amplifier U1 is powered only by positive voltage, supporting the input and output of positive voltage signals.

[0035] When leakage current flows through the connection resistor between the intermediate electrode of the series battery pack and the lithium battery protection chip, a voltage will be generated across the resistor. The micro-current detection circuit is used to differentially amplify this voltage and output it. Therefore, the micro-current detection circuit includes a differential amplifier circuit composed of operational amplifier U1 and peripheral circuitry, used to differentially amplify and output the voltage signal generated across the resistor.

[0036] The differential amplifier circuit described above is as follows: pin 3 of operational amplifier U1 is connected to resistors R1 and RF1 respectively, the other end of resistor R1 is the positive input of the micro-current detection circuit, and the other end of resistor RF1 is connected to GND; one end of resistor R2 is connected to the negative input of the micro-current detection circuit, and the other end is connected to pin 2 of operational amplifier U1, resistor RF2 and capacitor C1, and the other end of the connection between RF2 and C1 is connected to pin 1 of operational amplifier U1.

[0037] The output of pin 1 of operational amplifier U1 is connected to resistor R11, and the other end of R11 is connected to pin 5 of operational amplifier U1 and capacitor C7 respectively. Pins 5 and 7 of operational amplifier U1 are connected to resistor R12 to form a voltage follower circuit. The other end of resistor R12 is connected to capacitor C8 and capacitor J2 to output voltage signals. Pin 8 of operational amplifier U1 is connected to the positive voltage generated by the power supply circuit and capacitor C15.

[0038] In this embodiment, the negative voltage generating circuit includes a chip U5. Pins 4 and 8 are connected to the positive voltage generated by the power supply circuit. Pin 1 is connected to GND. Pin 5 is connected to capacitor C24. Pins 2 and 6 are connected to capacitor C30 and resistor R21. Pin 7 is connected to resistors R20 and R21 respectively. The other end of R20 is connected to a 15V power supply. The other end of R21 is connected to pin 6 of chip U5 and capacitor C30, thus forming a multivibrator circuit. The output frequency is output from pin 3 of chip U5. The formula for calculating the output frequency is: f = 1.44 / ((R20 + 2R21) + C30). Pin 3 of chip U5 is connected to the positive terminal of capacitor CE3. The negative terminal of capacitor CE3 is connected to the negative terminal of diode D1 and the positive terminal of diode D2 respectively. The positive terminal of diode D1 is connected to the negative terminal of capacitor CE4, and the negative terminal of diode D2 is connected to GND, forming a charge pump circuit. The chip U5 outputs a square wave voltage at pin 3. When the output is high, capacitor CE3 charges through diode D2; when the output is low, capacitor CE3 discharges through diode D1 and capacitor CE4, charging capacitor CE4. This cycle continues until CE3 and CE4 are fully charged, resulting in a negative voltage at the negative terminal of CE4.

[0039] The power supply circuit can select a 15V DC power strip J1 as the input, with pins 2 of J1 connected to GND; pin 1 of J1 is connected to inductor L1, and the other end of inductor L1 is connected to the positive terminals of capacitors C1E and C28, forming an LC filter circuit; the positive terminal of capacitor C28 is connected to the positive terminal of diode D3, and the negative terminal of D3 is connected to the positive terminals of capacitors CE2, C27, and C23, forming the positive voltage output terminal of the power supply circuit, and outputting a voltage slightly lower than 15V.

[0040] The power supply circuit can also select the highest output voltage of the battery pack itself, which is input through the positive terminal of diode D4. Taking lithium batteries as an example, each battery cell has a maximum voltage of 4.2V, and four batteries connected in series have a maximum voltage of 16.8V.

[0041] The above is only one specific embodiment of the present utility model, but the design concept of the present utility model is not limited thereto. Any non-substantial modifications made to the present utility model using this concept shall be deemed as an infringement of the protection scope of the present utility model.

Claims

1. A battery pack leakage detection circuit, characterized in that... include: Power supply circuit, negative voltage generation circuit, micro current detection circuit; The signal output terminal of the microcurrent detection circuit is connected to the two ends of the connection resistor between the intermediate electrode of the series battery pack and the lithium battery protection chip. By acquiring the signal output by the micro-current acquisition circuit and converting it into an absolute current value, the absolute current value is compared with a preset value to determine whether leakage has occurred. The power supply circuit and the negative voltage generating circuit are used to generate positive voltage and negative voltage power to the micro current detection circuit, respectively; the power supply circuit also supplies power to the negative voltage generating circuit.

2. The battery pack leakage detection circuit according to claim 1, characterized in that: The microcurrent detection circuit includes a differential amplifier circuit consisting of operational amplifier U1 and peripheral circuitry, used to differentially amplify and output the voltage signal generated across the resistor.

3. The battery pack leakage detection circuit according to claim 2, characterized in that: The microcurrent detection circuit also includes a voltage selection module, which is used to select positive voltage and negative voltage to power the operational amplifier U1, or to power the operational amplifier U1 only with positive voltage.

4. The battery pack leakage detection circuit according to claim 3, characterized in that: The voltage selection module includes 0-ohm resistors JR1 and JR2. The other end of JR1 is connected to the negative voltage generated by the negative voltage generating circuit, and the other end of JR2 is connected to GND and capacitor C16. The other end of C16 is connected to the negative voltage generated by the negative voltage generating circuit. Pin 4 of the operational amplifier U1 in the microcurrent detection circuit is connected to the 0-ohm resistors JR1 and JR2; When JR1 is selected, op-amp U1 is powered by both positive and negative voltages, supporting input and output of both positive and negative voltage signals; when JR2 is selected, op-amp U1 is powered only by positive voltage, supporting input and output of positive voltage signals.

5. A battery pack leakage detection circuit according to claim 4, characterized in that: Pin 3 of the operational amplifier U1 is connected to resistors R1 and RF1 respectively. The other end of resistor R1 is the positive input of the micro-current detection circuit, and the other end of resistor RF1 is connected to GND. One end of resistor R2 is connected to the negative input of the micro-current detection circuit, and the other end is connected to pin 2 of operational amplifier U1, resistor RF2 and capacitor C1. The other end of the connection between RF2 and C1 is connected to pin 1 of operational amplifier U1.

6. The battery pack leakage detection circuit according to claim 5, characterized in that: The output of pin 1 of the operational amplifier U1 is connected to R11, and the other end of R11 is connected to pin 5 of the operational amplifier U1 and C7 respectively; pin 5 and pin 7 of the operational amplifier U1 are connected to resistor R12, and the other end of resistor R12 is connected to C8 and J2 to output voltage signals; pin 8 of the operational amplifier U1 is connected to the positive voltage generated by the power supply circuit and capacitor C15.

7. A battery pack leakage detection circuit according to claim 1, characterized in that: The negative voltage generating circuit includes a chip U5, whose pins 4 and 8 are connected to the positive voltage generated by the power supply circuit, pin 1 is connected to GND, pin 5 is connected to capacitor C24, pins 2 and 6 are connected to capacitor C30 and resistor R21, pin 7 is connected to resistors R20 and R21 respectively, the other end of R20 is connected to the 15V power supply, the other end of R21 is connected to pin 6 of chip U5 and capacitor C30, and pin 3 is connected to the positive terminal of capacitor CE3; The negative terminal of capacitor CE3 is connected to the negative terminal of diode D1 and the positive terminal of diode D2, respectively; the positive terminal of diode D1 is connected to the negative terminal of capacitor CE4, and the negative terminal of diode D2 is connected to GND. The chip U5 outputs a square wave voltage at pin 3. When the output is high, capacitor CE3 is charged through diode D2. When the output is low, capacitor CE3 is discharged through diode D1 and capacitor CE4, and capacitor CE4 is charged.

8. A battery pack leakage detection circuit according to claim 1, characterized in that: The power supply circuit selects a 15V DC power supply connector J1 as the input, with pins 2 of J1 connected to GND; pin 1 of J1 is connected to inductor L1, and the other end of inductor L1 is connected to the positive terminals of capacitors C1E and C28, forming an LC filter circuit; the positive terminal of capacitor C28 is connected to the positive terminal of diode D3, and the negative terminal of D3 is connected to the positive terminals of capacitors CE2, C27, and C23, forming the positive voltage output terminal of the power supply circuit.

9. A battery pack leakage detection circuit according to claim 1, characterized in that: The power supply circuit selects the highest output voltage of the battery pack itself and inputs it through the positive terminal of diode D4.

10. A battery pack leakage detection circuit according to any one of claims 1-9, characterized in that: The microcurrent detection circuit can be one or more channels. When the microcurrent detection circuit is multiple channels, the circuit structure of each microcurrent detection circuit is the same.

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