A battery leakage current detection circuit and method

Abstract

The present invention relates to a battery leakage current detection circuit and method. The circuit includes a processor, a compensation current DAC unit, a constant current source, and a core ADC unit for collecting the battery voltage or a precision voltage-time conversion unit for collecting a high-precision time value corresponding to the battery voltage. A first input end of the compensation current DAC unit is connected to a first output end of the processor, a second input end of the compensation current DAC unit is connected to a reference unit, an output end of the compensation current DAC unit is connected to an input end of the constant current source, and an output end of the constant current source is connected to a first battery access end; a first input end of the core ADC unit or the precision voltage-time conversion unit is connected to a second battery access end, a second input end of the core ADC unit or the precision voltage-time conversion unit is connected to the reference unit, and an output end of the core ADC unit or the precision voltage-time conversion unit is connected to an input end of the processor. The present invention can quickly and accurately measure the magnitude of the leakage current of a battery or a capacitor.

Description

Technical Field

[0001] The invention belongs to the technical field of battery leakage current detection, and in particular relates to a battery leakage current detection circuit and method. Background Art

[0002] Due to objective reality issues such as defects in the working principles of batteries and capacitors, differences in production processes, or the technical level of raw materials, all produced batteries and capacitors have a certain amount of leakage current. This leakage current will cause the loss of stored energy in batteries and capacitors during long-term storage. The leakage current needs to be tested before the battery is shipped, which is used as a partial reference for battery classification. At the battery use terminal, the leakage current level of the battery also needs to be classified (for example, when batteries are used in parallel, batteries with the same leakage current level need to be selected, otherwise a battery with a large leakage current will leak the storage capacity of the entire battery pack).

[0003] At present, the common battery leakage current detection method used by battery manufacturers is to place the battery at room temperature for a period of time, generally one to two weeks, sometimes up to one month or even longer, and then test the battery voltage change during this period, and calculate the battery leakage current based on this. This solution has two obvious disadvantages: first, the test time is long, and second, the leakage current test accuracy is very low;

[0004] The invention patent with application number 201911108946.9 discloses a method for detecting leakage current of a lithium battery. The principle is: based on a given trial charging current, observe the slope of the time-voltage curve for a period of time to feedback and adjust the charging current; and when the slope is 0, take the charging current at this time as the leakage current of the battery. This method is slow (feedback adjustment can only be performed after obtaining the slope of the time-voltage curve), and this method does not provide how to eliminate the influence of temperature (temperature will directly affect the voltage of the battery, and then interfere with the slope of the time-voltage curve, so this method depends on a good constant temperature environment), and this method does not provide the essential principle of leakage current testing. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a battery leakage current detection circuit and method. The present invention can quickly and accurately test the leakage current of a battery or capacitor.

[0006] The technical solution of the present invention is implemented as follows: The present invention discloses a battery leakage current detection circuit, which includes a processor, a compensation current DAC unit, a constant current source, and a core ADC unit for collecting the battery voltage or a precision voltage-time conversion unit for collecting a high-precision time value corresponding to the battery voltage. The first input end of the compensation current DAC unit is connected to the first output end of the processor, the second input end of the compensation current DAC unit is connected to a reference unit, the output end of the compensation current DAC unit is connected to the input end of the constant current source, and the output end of the constant current source is connected to a first battery access end; the first input end of the core ADC unit or the precision voltage-time conversion unit is connected to a second battery access end, the second input end of the core ADC unit or the precision voltage-time conversion unit is connected to the reference unit, and the output end of the core ADC unit or the precision voltage-time conversion unit is connected to the input end of the processor.

[0007] Further, a first low-noise processing unit is provided at the first input end of the core ADC unit or the precision voltage-time conversion unit. The input end of the first low-noise processing unit is connected to the second battery access end, and the output end of the first low-noise processing unit is connected to the first input end of the core ADC unit or the precision voltage-time conversion unit.

[0008] Further, a second low-noise processing unit is provided between the second input end of the core ADC unit or the precision voltage-time conversion unit and the reference unit. The input end of the second low-noise processing unit is connected to the reference unit, and the output end of the second low-noise processing unit is connected to the second input end of the core ADC unit or the precision voltage-time conversion unit; a third low-noise processing unit is provided between the second input end of the compensation current DAC unit and the reference unit. The input end of the third low-noise processing unit is connected to the reference unit, and the output end of the third low-noise processing unit is connected to the second input end of the compensation current DAC unit.

[0009] Further, the battery leakage current detection circuit of the present invention further includes a battery voltage input polarity detection and switching unit. The input end of the battery voltage input polarity detection and switching unit is connected to the second battery access end, and the output end of the battery voltage input polarity detection and switching unit is connected to the first input end of the core ADC unit or the precision voltage-time conversion unit.

[0010] Further, the battery voltage input polarity detection and switching unit includes a CPU, a comparator, a first commutating relay, and a second commutating relay. The first end and the second end of the first commutating relay are respectively connected to both ends of the battery load. The first end and the second end of the second commutating relay are respectively connected to both ends of the battery load. The common end of the first commutating relay is connected to the first input end of the comparator. The common end of the second commutating relay is connected to the second input end of the comparator. The output end of the comparator is connected to the input end of the CPU. The CPU is used to judge the access polarity of the battery according to the output of the comparator, control the working states of the first commutating relay and the second commutating relay, and is used to switch the access polarity of the battery.

[0011] Further, the battery voltage input polarity detection and switching unit further includes a third relay. The first end of the third relay is connected to the common end of the first commutating relay. The second end of the third relay is connected to the common end of the second commutating relay. The output end of the third relay serves as the output end of the battery voltage input polarity detection and switching unit and is used to be connected to the first input end of the core ADC unit or the precision voltage-time conversion unit. The third relay is connected to the relay control circuit. The relay control circuit is connected to the output end of the CPU. The energization or de-energization of the coil of the third relay is controlled by the CPU.

[0012] Further, the battery leakage current detection circuit of the present invention further includes a high-impedance follower unit. The input end of the high-impedance follower unit is connected to the output end of the battery voltage input polarity detection and switching unit. The output end of the high-impedance follower unit is connected to the first input end of the core ADC unit or the precision voltage-time conversion unit.

[0013] The present invention discloses a method for quickly detecting battery leakage current, including the following steps:

[0014] Connect the positive and negative electrodes of the battery to the test loop, and the compensation current DAC unit outputs 0;

[0015] Collect the battery voltage through the core ADC unit, monitor the sampling value of the core ADC unit, and record the current sampling value X1 of the core ADC unit when the sampling value changes slowly to the battery self-discharge voltage change level;

[0016] As time goes by, the ADC sampling value will change. At this time, taking the X1 value as the setting and the current ADC sampling value as the feedback, introduce the PID control algorithm to control the outputs of the compensation current DAC unit and the constant current source;

[0017] By adjusting the PID parameters, make the ADC sampling value have no overshoot and no overshoot relative to X1;

[0018] When the output of the constant current source controlled by PID is stable, this current is the leakage current of the battery.

[0019] The present invention discloses a method for quickly detecting the leakage current of a battery, comprising the following steps:

[0020] Connect the positive and negative electrodes of the battery to the test loop, and the compensation current DAC unit outputs 0;

[0021] Collect the high-precision time value corresponding to the battery voltage through the precision voltage-time conversion unit, monitor the sampling value of the precision voltage-time conversion unit, and record the current sampling value X2 of the precision voltage-time conversion unit when the sampling value changes slowly to the level of the self-discharge voltage change of the battery;

[0022] As time goes by, the sampling value of the precision voltage-time conversion unit will change; at this time, taking the X2 value as the setting and the current sampling value of the precision voltage-time conversion unit as the feedback, introduce the PID control algorithm to control the outputs of the compensation current DAC unit and the constant current source;

[0023] By adjusting the PID parameters, make the sampling value of the precision voltage-time conversion unit have no overshoot and no overshoot relative to X2;

[0024] When the output of the constant current source controlled by PID is stable, this current is the leakage current of the battery.

[0025] Further, after arbitrarily connecting the positive and negative electrodes of the battery to the test loop, check the connection polarity of the battery through the battery voltage input polarity detection and switching unit. If the connection polarity of the battery is inaccurate, the input polarity is automatically reversed internally to ensure that the positive polarity of the battery voltage is output to the next stage.

[0026] The present invention has at least the following beneficial effects:

[0027] The battery leakage current detection circuit of the present invention includes a processor, a compensation current DAC unit, a constant current source, and a core ADC unit for collecting the battery voltage or a precision voltage-time conversion unit for collecting the high-precision time value corresponding to the battery voltage. The first input end of the compensation current DAC unit is connected to the first output end of the processor, the second input end of the compensation current DAC unit is connected to the reference unit, the output end of the compensation current DAC unit is connected to the input end of the constant current source, and the output end of the constant current source is connected to the first battery connection end; the first input end of the core ADC unit or the precision voltage-time conversion unit is connected to the second battery connection end, the second input end of the core ADC unit or the precision voltage-time conversion unit is connected to the reference unit, and the output end of the core ADC unit or the precision voltage-time conversion unit is connected to the input end of the processor. By adopting the above circuit, it can quickly and effectively feedback to the leakage current detection scheme of the battery or the capacitor, and improve the accuracy and speed of the battery leakage current detection.

[0028] The present invention determines the current access polarity of the battery by detecting the output of the CPU comparator; if the polarities are opposite, the commutation relay is controlled to commutate the battery input, and if the polarities are normal, no action is taken. By placing the comparator after the high-impedance follower unit, it can be ensured that the battery automatic commutation circuit has no impact on the battery. To avoid human errors, when the battery is connected, there is no need to worry about the battery polarity. The battery polarity can be adjusted to the polarity required by the leakage current inspection circuit by this circuit structure.

[0029] This solution can also be used to ensure that only single polarity needs to be considered during leakage current detection. This technology can ensure that the battery or capacitor can be connected arbitrarily and the leakage current of the battery or capacitor can be tested normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic block diagram of a battery leakage current detection circuit according to an embodiment provided by the present invention;

[0032] Figure 2 It is a schematic block diagram of a battery voltage input polarity detection and switching unit according to an embodiment provided by the present invention;

[0033] Figure 3 It is a specific circuit diagram of a battery voltage input polarity detection and switching unit according to an embodiment provided by the present invention;

[0034] Figure 4 It is a specific circuit diagram of a core ADC unit and a first low-noise processing unit according to an embodiment provided by the present invention;

[0035] Figure 5 It is a circuit diagram of a high-precision low-temperature drift reference and a low-noise processing unit according to an embodiment provided by the present invention;

[0036] Figure 6 It is a flowchart of a battery leakage current detection method according to an embodiment provided by the present invention;

[0037] Figure 7 It is a schematic block of another embodiment of a battery leakage current detection circuit provided by the present invention;

[0038] Figure 8 It is a flowchart of another embodiment of a battery leakage current detection method provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0040] Embodiment 1

[0041] See Figures 1 to 5 , the embodiment of the present invention provides a battery leakage current detection circuit, including a processor, a compensation current DAC unit, a constant current source, and a core ADC unit for collecting battery voltage. The first input end of the compensation current DAC unit is connected to the first output end of the processor, the second input end of the compensation current DAC unit is connected to the reference unit, the output end of the compensation current DAC unit is connected to the input end of the constant current source, and the output end of the constant current source is connected to the first battery access end; the first input end of the core ADC unit is connected to the second battery access end, the second input end of the core ADC unit is connected to the reference unit, and the output end of the core ADC unit is connected to the input end of the processor.

[0042] In this embodiment, the core ADC unit collects the battery voltage; and controls the output current of the compensation current DAC unit and the multi-range constant current source based on this; so as to ensure that the voltage sampling value of the core ADC unit remains unchanged;

[0043] In this embodiment, the multi-current range constant current source requires low noise to ensure that it does not interfere with the sampling of the ADC unit when the constant current source is working;

[0044] The core ADC in this embodiment requires low drift, high resolution, and high stability.

[0045] Further, a first low-noise processing unit is provided at the first input end of the core ADC unit. The input end of the first low-noise processing unit is connected to the second battery access end, and the output end of the first low-noise processing unit is connected to the first input end of the core ADC unit.

[0046] Further, a second low-noise processing unit is provided between the second input end of the core ADC unit and the reference unit. The input end of the second low-noise processing unit is connected to the reference unit, and the output end of the second low-noise processing unit is connected to the second input end of the core ADC unit; a third low-noise processing unit is provided between the second input end of the compensation current DAC unit and the reference unit. The input end of the third low-noise processing unit is connected to the reference unit, and the output end of the third low-noise processing unit is connected to the second input end of the compensation current DAC unit.

[0047] A second low-noise processing unit is provided between the second input terminal of the core ADC unit and the reference unit. The reference unit uses the second low-noise processing unit to provide a reference voltage source for the core ADC unit. The input terminal of the second low-noise processing unit is connected to the reference unit, and the output terminal of the second low-noise processing unit is connected to the second input terminal of the core ADC unit; a third low-noise processing unit is provided between the second input terminal of the compensation current DAC unit and the reference unit. The reference unit uses the third low-noise processing unit to provide a reference voltage source for the compensation current DAC unit. The input terminal of the third low-noise processing unit is connected to the reference unit, and the output terminal of the third low-noise processing unit is connected to the second input terminal of the compensation current DAC unit.

[0048] The compensation current DAC unit drives a constant current source module with multiple current ranges to compensate for the leakage current of the battery.

[0049] In this embodiment, the reference unit uses a high-precision low-temperature drift reference. The constant current source in this embodiment uses a constant current source with multiple current ranges.

[0050] The present invention realizes lossless and interference-free transformation and transmission of signals through a selected low-noise processing unit. The present invention outputs a voltage reference source signal through a preferred high-precision low-temperature drift reference, only requiring low-temperature drift output, and other requirements are not limited. Because the accuracy is very good under the reference of low-temperature drift; it can not only save circuit losses, but also effectively reduce power consumption. The voltage reference signal is input to the front-stage low-noise processing unit to further reduce the noise of the reference voltage signal, improve the driving ability and then input it into the core ADC unit. Based on this, the chip models of specific units are selected. The battery signal to be measured is connected to the first low-noise processing unit for noise reduction processing. Through the selected low-noise processing unit, the extremely high impedance of the signal to be measured is sampled, and after further reducing the noise, it is output to the input stage of the core ADC.

[0051] The high-precision low-temperature drift reference includes any one of LTZ1000, LTC6655, LTC6657 or ADR4550C / D voltage reference devices with a temperature drift index better than 1 ppm / °C. The low-noise processing unit includes any one of ADA4528, ADA4523 or MAX44246, with a low drift less than 1 ppm / °C, a low-noise peak-to-peak value of less than 200 nV in the low-frequency part and less than 10 nV / sqrt(Hz) in the high-frequency part. And the input base current Ibase of the input low-noise processing unit is less than 1 nA.

[0052] Furthermore, high-resolution low-temperature drift voltage acquisition is realized through a selected core ADC unit; the core ADC unit can be a 24-bit precision ADC such as AD7175, AD7124, AD7176, LTC2449, etc., but is not limited to the above embodiments.

[0053] Furthermore, the battery leakage current detection circuit of the present invention further includes a battery voltage input polarity detection and switching unit. The input end of the battery voltage input polarity detection and switching unit is connected to the second battery access end, and the output end of the battery voltage input polarity detection and switching unit is connected to the first input end of the core ADC unit.

[0054] Furthermore, the battery leakage current detection circuit of the present invention further includes a high-impedance follower unit. The input end of the high-impedance follower unit is connected to the output end of the battery voltage input polarity detection and switching unit, and the output end of the high-impedance follower unit is connected to the first input end of the core ADC unit.

[0055] The input end of the first low-noise processing unit in this embodiment is connected to the output end of the battery voltage input polarity detection and switching unit or the output end of the high-impedance follower unit, and the output end of the first low-noise processing unit is connected to the first input end of the core ADC unit.

[0056] Furthermore, the battery voltage input polarity detection and switching unit includes a CPU, a comparator, a first commutating relay, and a second commutating relay. The first end and the second end of the first commutating relay are respectively connected to both ends of the battery load, and the first end and the second end of the second commutating relay are respectively connected to both ends of the battery load. The common end of the first commutating relay is connected to the first input end of the comparator, and the common end of the second commutating relay is connected to the second input end of the comparator. The output end of the comparator is connected to the input end of the CPU. The CPU is used to judge the access polarity of the battery according to the output of the comparator, control the working states of the first commutating relay and the second commutating relay, and is used to switch the access polarity of the battery.

[0057] A relay control circuit is arranged between the CPU and the first commutating relay and the second commutating relay to control the energization or de-energization of the coils of each relay through the relay control circuit.

[0058] Furthermore, a first high-impedance follower unit can be arranged in the battery voltage input polarity detection and switching unit of the present invention. The input end of the first high-impedance follower unit is connected to the common end of the first commutating relay, and the output end of the first high-impedance follower unit is connected to the first input end of the comparator. Placing the comparator behind the first high-impedance follower unit can ensure that the battery automatic commutation circuit has no influence on the battery.

[0059] By combining the connections of two reversing relays, multiple connection methods can be formed, mainly including two: If the voltage or current at the output terminal of the CPU detection comparator is positive, it means that the common terminal of the first relay K2B is connected to the positive pole of the battery load, and the common terminal of the second relay is connected to the negative pole of the battery load, forming a circuit; If the voltage or current at the output terminal of the CPU detection comparator is negative, it means that the common terminal of the first relay K2B is connected to the negative pole of the battery load, and the common terminal of the second relay is connected to the positive pole of the battery load, forming a circuit. Among them, the reversing relay is used to connect the battery to the circuit according to different selection combinations.

[0060] Connect the battery load to this circuit, detect the current comparator output through the CPU, and judge the current battery input polarity; If the polarity is correct, no action is taken; If the polarity is incorrect, control the reversing relay to switch the battery input polarity.

[0061] By placing the comparator after the first high-impedance follower unit, it can be ensured that the battery automatic reversing circuit has no impact on the battery. To avoid human error, when connecting the battery, there is no need to worry about the battery polarity. The battery polarity can be adjusted to the polarity required by the leakage current inspection circuit by this circuit structure.

[0062] Furthermore, the battery voltage input polarity detection and switching unit further includes a third relay K3B. The first end of the third relay K3B is connected to the common terminal of the first reversing relay, and the second end of the third relay K3B is connected to the common terminal of the second reversing relay. The output end of the third relay K3B can be used as the output end of the battery voltage input polarity detection and switching unit.

[0063] The third relay is connected to the relay control circuit, and the relay control circuit is connected to the output terminal of the CPU. The energization or de-energization of the coil of the third relay is controlled by the CPU.

[0064] Furthermore, the first end of the third relay K3B can be connected to the output end of the first high-impedance follower unit or the common terminal of the first reversing relay.

[0065] Furthermore, the first high-impedance follower unit includes a first operational amplifier. The positive input terminal of the first operational amplifier is electrically connected to the common terminal of the first reversing relay, and the negative input terminal and the output terminal of the first operational amplifier are connected together to the first input terminal of the comparator. The connection method of the first operational amplifier U1A is as shown in the figure and will not be elaborated here.

[0066] Furthermore, a second high-impedance follower unit is also provided at the output end of the battery voltage input polarity detection and switching unit. The input end of the second high-impedance follower unit is connected to the common end of the third relay K3B or the output end of the first high-impedance follower unit, and the output end of the second high-impedance follower unit is connected to the first input end of the core ADC unit. The second high-impedance follower unit plays a role in isolation and protection.

[0067] Furthermore, the commutation relay and the battery load are connected through a safety switch K1B. When a short circuit or other faults occur in the circuit, the connection of the battery load can be disconnected by opening the safety switch K1B.

[0068] The battery voltage input polarity detection and switching unit can ensure that the battery or capacitor can be connected arbitrarily and the battery or capacitor leakage current can be tested normally.

[0069] See Figure 6 , this embodiment also discloses a method for quickly detecting battery leakage current, including the following steps:

[0070] The positive and negative electrodes of the battery are connected to the test loop arbitrarily, and the compensation current DAC unit outputs 0;

[0071] The battery voltage input polarity detection and switching unit checks the connection polarity of the battery and automatically commutes internally to ensure that the positive polarity of the battery voltage is output to the subsequent stage;

[0072] Monitor the sampling values of the core ADC unit for a period of time. When the sampling values change slowly to the level of the battery self-discharge voltage change, record the current sampling value X1 of the core ADC unit;

[0073] As time goes by, the ADC sampling values will change; at this time, taking the X1 value as the setting and the current ADC sampling value as the feedback, introduce the PID control algorithm to implement a general negative feedback control system to control the output of the compensation current DAC unit and the constant current source;

[0074] By adjusting the PID parameters, make the ADC sampling value have no overshoot and no overshoot relative to X1;

[0075] When the output of the constant current source controlled by PID is stable, this current is the leakage current of the battery.

[0076] Embodiment 2

[0077] See Figure 7, this embodiment provides a battery leakage current detection circuit. In this embodiment, only the core ADC unit for collecting the battery voltage in Embodiment 1 is replaced with a precision voltage-time conversion unit for collecting the high-precision time value corresponding to the battery voltage, and other technical features are exactly the same as those in Embodiment 1.

[0078] In this embodiment, the precision voltage-time conversion unit collects the high-precision time value corresponding to the battery voltage; and based on this, controls the output currents of the compensation current DAC unit and the multi-range constant current source; so as to ensure that the high-precision time value collected by the precision voltage-time conversion unit corresponding to the battery voltage remains unchanged;

[0079] The constant current source in this embodiment is a multi-range constant current source, which requires low noise to ensure that the constant current source does not interfere with the sampling of the precision voltage-time conversion unit when it works;

[0080] The precision voltage-time conversion unit in this embodiment adopts the publicly available technologies (single-slope, dual-slope, multi-slope integration technologies).

[0081] See Figure 8 , this embodiment also discloses a fast battery leakage current detection method, including the following steps:

[0082] Arbitrarily connect the positive and negative electrodes of the battery to the test loop, and the compensation current DAC unit outputs 0;

[0083] The battery voltage input polarity detection and switching unit checks the connection polarity of the battery and automatically reverses internally to ensure that the positive polarity of the battery voltage is output to the next stage;

[0084] Monitor the sampling values of the precision voltage-time conversion unit for a period of time. When the sampling values change slowly to the level of the battery self-discharge voltage change, record the current sampling value X2 of the precision voltage-time conversion unit;

[0085] As time goes by, the sampling values of the precision voltage-time conversion unit will change; at this time, taking the value of X2 as the set value and the current sampling value of the precision voltage-time conversion unit as the feedback, introduce the PID control algorithm to implement a general negative feedback control system to control the outputs of the compensation current DAC unit and the multi-range constant current source;

[0086] Through appropriate PID parameters, make the sampling values of the precision voltage-time conversion unit have no overshoot and no overshoot relative to X2;

[0087] When the output of the constant current source controlled by PID is stable, this current is the leakage current of the battery.

[0088] The core principle of this method for testing leakage current: to measure the relative voltage of a battery with ultra-high precision and constancy; this voltage only requires ultra-high stability and ultra-high resolution, and does not require absolute precision; for example, if the current battery voltage is x.xxxxxxx V, there is no need to care whether it is exactly 3.7654321V or other specific voltages. Just use the current relative value x.xxxxxxx V as the control reference.

[0089] The technical solution of the present invention is applicable to the leakage current detection of various batteries and capacitors, including but not limited to secondary batteries of various technologies such as button batteries, soft-pack batteries, cylindrical batteries, and aluminum-shell batteries, and various primary batteries in square and cylindrical shapes, as well as capacitors of various technologies.

[0090] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A battery leakage current detection circuit, characterized in that: It includes a processor, a compensation current DAC unit, a constant current source, and a core ADC unit for collecting the battery voltage or a precision voltage-time conversion unit for collecting the high-precision time value corresponding to the battery voltage. The first input end of the compensation current DAC unit is connected to the first output end of the processor. The second input end of the compensation current DAC unit is connected to a reference unit. The output end of the compensation current DAC unit is connected to the input end of the constant current source. The output end of the constant current source is connected to a first battery connection end. The first input end of the core ADC unit or the precision voltage-time conversion unit is connected to a second battery connection end. The second input end of the core ADC unit or the precision voltage-time conversion unit is connected to the reference unit. The output end of the core ADC unit or the precision voltage-time conversion unit is connected to the input end of the processor; It further includes a battery voltage input polarity detection and switching unit. The input end of the battery voltage input polarity detection and switching unit is connected to the second battery connection end. The output end of the battery voltage input polarity detection and switching unit is connected to the first input end of the core ADC unit or the precision voltage-time conversion unit; The battery voltage input polarity detection and switching unit includes a CPU, a comparator, a first commutation relay, and a second commutation relay. The first end and the second end of the first commutation relay are respectively connected to both ends of a battery load. The first end and the second end of the second commutation relay are respectively connected to both ends of the battery load. The common end of the first commutation relay is connected to the first input end of the comparator. The common end of the second commutation relay is connected to the second input end of the comparator. The output end of the comparator is connected to the input end of the CPU. The CPU is used to judge the connection polarity of the battery according to the output of the comparator, control the working states of the first commutation relay and the second commutation relay, and is used to switch the connection polarity of the battery; It further includes a high-impedance following unit. The input end of the high-impedance following unit is connected to the output end of the battery voltage input polarity detection and switching unit. The output end of the high-impedance following unit is connected to the first input end of the core ADC unit or the precision voltage-time conversion unit.

2. The battery leakage current detection circuit according to claim 1, wherein: A first low-noise processing unit is provided at the first input end of the core ADC unit or the precision voltage-time conversion unit. The input end of the first low-noise processing unit is connected to the second battery connection end. The output end of the first low-noise processing unit is connected to the first input end of the core ADC unit or the precision voltage-time conversion unit.

3. The battery leakage current detection circuit according to claim 1, wherein: A second low-noise processing unit is provided between the second input end of the core ADC unit or the precision voltage-time conversion unit and the reference unit. The input end of the second low-noise processing unit is connected to the reference unit. The output end of the second low-noise processing unit is connected to the second input end of the core ADC unit or the precision voltage-time conversion unit. A third low-noise processing unit is provided between the second input end of the compensation current DAC unit and the reference unit. The input end of the third low-noise processing unit is connected to the reference unit. The output end of the third low-noise processing unit is connected to the second input end of the compensation current DAC unit.

4. The battery leakage current detection circuit according to claim 1, characterized in that: The battery voltage input polarity detection and switching unit further includes a third relay. The first end of the third relay is connected to the common end of the first commutation relay, and the second end of the third relay is connected to the common end of the second commutation relay. The output end of the third relay serves as the output end of the battery voltage input polarity detection and switching unit and is used to connect to the first input end of the core ADC unit or the precision voltage-time conversion unit. The third relay is connected to the relay control circuit, and the relay control circuit is connected to the output end of the CPU. The energization or de-energization of the coil of the third relay is controlled by the CPU.

5. A method for quickly detecting battery leakage current, characterized in that, The battery leakage current detection circuit as described in any one of claims 1 to 4 is adopted; The battery leakage current rapid detection method includes the following steps: Connect the positive and negative electrodes of the battery to the test loop, and the compensation current DAC unit outputs 0; Collect the battery voltage through the core ADC unit, monitor the sampling value of the core ADC unit, and record the current sampling value X1 of the core ADC unit when the sampling value changes slowly to the battery self-discharge voltage change level; As time goes by, the ADC sampling value will change. At this time, using the X1 value as the set value and the current ADC sampling value as the feedback, introduce the PID control algorithm to control the output of the compensation current DAC unit and the constant current source; By adjusting the PID parameters, make the ADC sampling value have no overshoot and no overshoot relative to X1; When the output of the constant current source controlled by PID is stable, this current is the leakage current of the battery.

6. A method for quickly detecting the leakage current of a battery, characterized in that, The battery leakage current detection circuit as described in any one of claims 1 to 4 is adopted; The battery leakage current rapid detection method includes the following steps: Connect the positive and negative electrodes of the battery to the test loop, and the compensation current DAC unit outputs 0; Collect the high-precision time value corresponding to the battery voltage through the precision voltage-time conversion unit, monitor the sampling value of the precision voltage-time conversion unit, and record the current sampling value X2 of the precision voltage-time conversion unit when the sampling value changes slowly to the battery self-discharge voltage change level; As time goes by, the sampling value of the precision voltage-time conversion unit will change. At this time, using the X2 value as the set value and the current sampling value of the precision voltage-time conversion unit as the feedback, introduce the PID control algorithm to control the output of the compensation current DAC unit and the constant current source; By adjusting the PID parameters, make the sampling value of the precision voltage-time conversion unit have no overshoot and no overshoot relative to X2; When the output of the constant current source controlled by PID is stable, this current is the leakage current of the battery.

7. The method according to claim 5 or 6, characterized in that: After the positive and negative electrodes of the battery are arbitrarily connected to the test loop, check the connection polarity of the battery through the battery voltage input polarity detection and switching unit. If the connection polarity of the battery is inaccurate, the input polarity is automatically reversed internally to ensure that the positive polarity of the battery voltage is output to the next stage.

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