A fast battery leakage current detection system and method

Abstract

The present invention relates to a battery leakage current rapid detection system and method. The system includes an ADC unit, a compensation current DAC unit, and a processor. 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 a 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 ADC unit is connected to an output end of an adder circuit, a second input end of the ADC unit is connected to the reference unit, an output end of the ADC unit is connected to an input end of the processor, and a first input end of the adder circuit is connected to a second battery access end; a second input end of the adder circuit is connected to an output end of a core DAC unit, a first input end of the core DAC unit is connected to a second output end of the processor, and a second input end of the core DAC unit is connected to the reference unit. The present invention can rapidly and accurately measure the magnitude of the leakage current of a battery or a capacitor.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery leakage current detection, and particularly relates to a battery leakage current rapid detection system and method. Background Art

[0002] Due to objective practical problems such as the principle defects of batteries and capacitors in operation, production process differences, or raw material technical levels, various produced batteries and capacitors all have a certain amount of leakage current more or less; this leakage current will cause energy loss during the long-term storage of batteries and capacitors; before the battery is shipped, it is necessary to detect the leakage current, which is used as part of the reference basis for battery classification. At the battery usage terminal, it is also necessary to classify the leakage current level of the battery (for example, when batteries are used in parallel, then 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] Currently, the common method for battery production enterprises to detect battery leakage current is to place the battery at room temperature for a period of time, generally one to two weeks, and some up to one month or even longer, and then measure the voltage change of the battery during this period, and calculate the leakage current of the battery based on this. This solution has two obvious disadvantages: one is the long test time, and the other is the very low accuracy of the measured leakage current.

[0004] The invention patent with the application number 201911108946.9 discloses a method for detecting the leakage current of a lithium battery. Its principle is: based on a given tentative 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 has the disadvantages of slow speed (feedback adjustment can only be carried out after obtaining the slope of the time-voltage curve), and this method does not give 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 the implementation of this method depends on a good constant temperature environment), and this method does not give 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 provides a battery leakage current rapid detection system and method, which can quickly and accurately measure the magnitude of the leakage current of a battery or a capacitor.

[0006] The technical solution of the present invention is implemented as follows: The present invention discloses a fast battery leakage current detection system, including a core DAC unit, an ADC unit, an adder circuit, a constant current source, a compensation current DAC unit, and a processor. 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 access end. The first input end of the ADC unit is connected to the output end of the adder circuit. The second input end of the ADC unit is connected to the reference unit. The output end of the ADC unit is connected to the input end of the processor. The first input end of the adder circuit is connected to a second battery access end. The second input end of the adder circuit is connected to the output end of the core DAC unit. The first input end of the core DAC unit is connected to the second output end of the processor. The second input end of the core DAC unit is connected to the reference unit.

[0007] Further, a first low-noise processing unit is provided between the second input end of the core DAC unit and the reference unit. The input end of the first low-noise processing unit is connected to the reference unit. The output end of the first low-noise processing unit is connected to the second input end of the core DAC unit. A second low-noise processing unit is provided between the second input end of the ADC 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 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. The output end of the third low-noise processing unit is connected to the second input end of the compensation current DAC unit.

[0008] Further, a fourth low-noise processing unit is provided between the output end of the core DAC unit and the fourth input end of the adder circuit. The input end of the fourth low-noise processing unit is connected to the output end of the core DAC unit. The output end of the fourth low-noise processing unit is connected to the fourth input end of the adder circuit.

[0009] Further, an amplification unit is provided between the output end of the adder circuit and the first input end of the ADC unit. The input end of the amplification unit is connected to the output end of the adder circuit. The output end of the amplification unit is connected to the first input end of the ADC unit.

[0010] Further, the adder circuit is used to receive the reverse input of the battery voltage and the voltage output by the core DAC unit, merge and output, then amplify by a set multiple and access the ADC unit for precise differential voltage sampling.

[0011] Further, the battery leakage current rapid detection system of the present invention further includes a battery reverse input polarity detection unit. The input end of the battery reverse input polarity detection unit is connected to the second battery access end, and the output end of the battery reverse input polarity detection unit is connected to the first input end of the addition circuit.

[0012] Further, the battery reverse input polarity detection 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 the 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 access 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 access polarity of the battery.

[0013] Further, the battery leakage current rapid detection system 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 reverse input polarity detection unit, and the output end of the high impedance follower unit is connected to the first input end of the addition circuit.

[0014] The present invention discloses a method for rapidly detecting battery leakage current, including the following steps:

[0015] S1) Connect the positive and negative electrodes of the battery to the test loop to reverse the output of the battery voltage to the test loop;

[0016] S2) Output 1 / 2 full scale by the core DAC unit;

[0017] S3) Detect the output of the ADC unit and compare it with the set value. If the output of the ADC unit is too large or overflows, adjust the core DAC output to 1 / 4 full scale. If the output of the ADC unit is too small or underflows, adjust the core DAC output to 3 / 4 full scale;

[0018] S4) Return to step S3), adjust the output of the core DAC unit to make the output of the ADC unit meet the set requirements;

[0019] S5) Monitor the ADC sampling value output by the ADC unit. When the change of the ADC sampling value is slow to the level of the battery self-discharge voltage change, record the current ADC sampling value X of the ADC unit;

[0020] S6) As time goes by, the ADC sampling value will change. At this time, use the X value as the setting, use the current ADC sampling value as the feedback, introduce the PID control algorithm, and control the output of the compensation current DAC unit and the constant current source;

[0021] S7) When the output of the constant current source controlled by PID is stable, the output current of the constant current source at this time is the leakage current of the battery.

[0022] Further, after the positive and negative electrodes of the battery are arbitrarily connected to the test loop, the battery connection polarity is checked by the battery reverse input polarity detection unit. If the battery connection polarity is inaccurate, the input polarity is automatically reversed internally to ensure that the battery voltage is output in reverse to the next stage. The reverse input of the battery voltage and the voltage output by the core DAC form a precision adder circuit. Specifically, the negative battery voltage plus the positive core DAC output voltage will cancel each other out to a very weak signal, and then it is amplified by a certain multiple precisely and then enters the detection ADC; in this way, the weak change of the battery voltage can be detected.

[0023] Further, during the PID control process, through the adjustment of PID parameters, the ADC sampling value has no overshoot and no overshoot relative to the X value.

[0024] Further, step S4) adjusts the output of the core DAC unit by the dichotomy method.

[0025] Further, the output of the ADC unit in step S4) meeting the requirements means that the output of the ADC unit is closest to the set value.

[0026] In step S4), when the output of the ADC unit meets the requirements, the output of its core DAC unit is M, and after the output of the ADC unit meets the requirements in step S4), the output of the core DAC unit is maintained at M.

[0027] Further, the set value is 1 / 2 full scale of the output of the ADC unit.

[0028] The present invention has at least the following beneficial effects:

[0029] The battery leakage current rapid detection system of the present invention includes a core DAC unit, an ADC unit, an adder circuit, a constant current source, a compensation current DAC unit, and a processor. 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 access end. The first input end of the ADC unit is connected to the output end of the adder circuit. The second input end of the ADC unit is connected to the reference unit. The output end of the ADC unit is connected to the input end of the processor. The first input end of the adder circuit is connected to a second battery access end. The second input end of the adder circuit is connected to the output end of the core DAC unit. The first input end of the core DAC unit is connected to the second output end of the processor. The second input end of the core DAC unit is connected to the reference unit. By adopting the above circuit, in the leakage current detection scheme of a battery or a capacitor, the accuracy and speed of battery leakage current detection can be improved and effectively fed back.

[0030] The present invention detects the output of a CPU comparator to judge the current access polarity of a battery. If the polarities are opposite, a commutation relay is controlled to commutate the battery input. If the polarities are normal, no action is taken. By placing the comparator behind a high-impedance follower unit, it can be ensured that the battery automatic commutation circuit has no influence on the battery. The situation of human error is avoided. When the battery is accessed, the battery polarity does not need to be considered. The battery polarity can be adjusted to the polarity required by the leakage current inspection circuit by this circuit structure.

[0031] This solution can also be used to ensure that only a single polarity needs to be considered during leakage current detection. This technology can ensure that the battery or capacitor can be accessed arbitrarily and the leakage current of the battery or capacitor can be tested normally. Brief Description of the Drawings

[0032] 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 following drawings 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.

[0033] Figure 1 It is a principle block diagram of the battery leakage current rapid detection system provided by the embodiment of the present invention;

[0034] Figure 2 It is a principle block diagram of the battery reverse input polarity detection unit provided by the embodiment of the present invention;

[0035] Figure 3Specific circuit diagram of the battery reverse input polarity detection unit provided by the embodiment of the present invention;

[0036] Figure 4 Circuit diagram of the high-precision low-temperature drift reference and low-noise processing unit provided by the embodiment of the present invention;

[0037] Figure 5 Flow chart of the battery leakage current rapid detection method provided by the embodiment of the present invention. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. 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 creative efforts shall fall within the protection scope of the present invention.

[0039] Embodiment 1

[0040] Refer to Figures 1 to 4 , the embodiment of the present invention provides a battery leakage current rapid detection system, including a core DAC unit, an ADC unit, an adder circuit, a constant current source, a compensation current DAC unit, and a processor. 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 ADC unit is connected to the output end of the adder circuit, the second input end of the ADC unit is connected to the reference unit, the output end of the ADC unit is connected to the input end of the processor, and the first input end of the adder circuit is connected to the second battery access end; the second input end of the adder circuit is connected to the output end of the core DAC unit, the first input end of the core DAC unit is connected to the second output end of the processor, and the second input end of the core DAC unit is connected to the reference unit.

[0041] The core DAC unit and the reverse battery voltage are combined and output through an adder circuit, and then amplified by a set multiple (the set multiple in this embodiment can be 1000 times, but it is not limited to 1000 times), and then connected to the ADC unit for precise differential voltage sampling; the ADC unit outputs the sampled value to the processor, and the processor controls the output of the compensation current DAC unit according to the sampled value of the ADC unit, so as to drive the output current of the constant current source to ensure that the precise differential voltage sampled value remains unchanged. Due to this 1000-fold amplification, even if a very small signal is input at the input stage, overflows or underflows will occur at the output stage. For example, if the reference voltage of the detected ADC is 5V, then an input of only 5mV at the input stage can cause the detected ADC to overflow; the output of the core DAC and the reverse battery voltage will cancel each other out. By controlling the output of the core DAC (using the dichotomy method), the voltage output by the adder circuit is made very small (about 2.5mV), so that the value of the detected ADC is around 50% of full scale. Then, by keeping the output of the core DAC unchanged, the change in the weak battery voltage will ultimately be reflected in the detected ADC.

[0042] This system determines the control signal of the compensation current DAC unit through precise differential voltage sampling.

[0043] The constant current source of this system is required to have low noise to ensure that it does not interfere with the sampling of the ADC unit when it is working.

[0044] The core DAC unit of this system is required to have low output drift and low noise; the output of the core DAC unit of this system is determined by precise differential voltage sampling, and the output of the core DAC is adjusted by the dichotomy method so that the output of the precise differential voltage sampling ADC is near half value.

[0045] Further, a first low-noise processing unit is provided between the second input terminal of the core DAC unit and the reference unit, and the reference unit uses the first low-noise processing unit as a reference voltage source for the core DAC. The input terminal of the first low-noise processing unit is connected to the reference unit, and the output terminal of the first low-noise processing unit is connected to the second input terminal of the core DAC unit; a second low-noise processing unit is provided between the second input terminal of the ADC unit and the reference unit, and the reference unit uses the second low-noise processing unit as a reference voltage source for the 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 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, and the reference unit uses the third low-noise processing unit as 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.

[0046] Further, a fourth low-noise processing unit is provided between the output end of the core DAC unit and the fourth input end of the adder circuit. The input end of the fourth low-noise processing unit is connected to the output end of the core DAC unit, and the output end of the fourth low-noise processing unit is connected to the fourth input end of the adder circuit.

[0047] The reference unit of this embodiment uses a high-precision low-temperature-drift reference. The adder circuit of this embodiment uses a high-precision low-temperature-drift adder circuit. The constant current source of this embodiment uses a multi-current-range constant current source. The compensation current DAC unit drives the multi-current-range constant current source module to compensate for the leakage current of the battery.

[0048] The present invention realizes the lossless and interference-free transformation and transmission of signals through the selected low-noise processing unit. The present invention outputs a voltage reference source signal through the preferred high-precision low-temperature-drift reference, and only requires low temperature drift, and other requirements are not limited. Because the accuracy is very good under the low-temperature-drift reference; not only can the circuit loss be saved, but the power consumption can also be effectively reduced. The voltage reference signal is input to the pre-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 ADC unit. Based on this, the chip models of specific units are selected. The high-precision low-temperature-drift reference includes any one of LTZ1000, LTC6655, LTC6657 or ADR4550C / D 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 / square root (Hz) in the high-frequency part. And the input base current Ibase of the input low-noise processing unit is less than 1 nA.

[0049] Further, high-resolution low-temperature-drift voltage acquisition is realized through the selected ADC unit; the ADC unit can be a 24-bit precision ADC such as AD7175, AD7124, AD7176, LTC2449, etc., but is not limited to the above embodiments.

[0050] Further, an amplification unit is provided between the output end of the high-precision low-temperature-drift adder circuit and the first input end of the ADC unit. The input end of the amplification unit is connected to the output end of the high-precision low-temperature-drift adder circuit, and the output end of the amplification unit is connected to the first input end of the ADC unit. The amplification factor of the amplification unit in this embodiment is 1000 times. Of course, it is not limited to 1000 times.

[0051] Furthermore, the battery leakage current rapid detection system of the present invention further includes a battery reverse input polarity detection unit. The input end of the battery reverse input polarity detection unit is connected to the second battery access end, and the output end of the battery reverse input polarity detection unit is connected to the first input end of the high-precision low-temperature drift addition circuit.

[0052] Furthermore, the battery leakage current rapid detection system 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 reverse input polarity detection unit, and the output end of the high-impedance follower unit is connected to the first input end of the high-precision low-temperature drift addition circuit.

[0053] Furthermore, the battery reverse input polarity detection 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 the 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 access 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 access polarity of the battery.

[0054] Furthermore, a first high-impedance follower unit is arranged in the battery reverse input polarity detection unit of the present invention. The input end of the first high-impedance follower unit is connected to the common end of the first commutation relay, and the output end 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.

[0055] It can be seen that through the combined connection of two commutation relays, multiple connection methods can be formed, mainly including two: if the voltage or current at the output end of the comparator is detected as positive by the CPU, it means that the common end of the first relay K2B is connected to the positive pole of the battery load, and the common end of the second relay is connected to the negative pole of the battery load, forming a loop; if the voltage or current at the output end of the comparator is detected as negative by the CPU, it means that the common end of the first relay K2B is connected to the negative pole of the battery load, and the common end of the second relay is connected to the positive pole of the battery load, forming a loop. Among them, the commutation relay is used to connect the battery into the circuit according to different selection combinations.

[0056] Connect the battery load to this circuit; the CPU detects the current output of the comparator and judges the current battery input polarity; if the polarity is correct, no action is taken; if the polarity is incorrect, the commutation relay is controlled to switch the battery input polarity.

[0057] By placing the comparator after the first 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 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.

[0058] Further, the battery reverse input polarity detection unit further includes a third relay K3B. The first end of the third relay K3B is connected to the common end of the first commutation relay, and the second end of the third relay K3B is connected to the common end of the second commutation relay. The output end of the third relay K3B can be used as the output end of the battery reverse input polarity detection unit.

[0059] 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.

[0060] Further, the first end of the third relay K3B is connected to the output end of the first high-impedance follower unit. The third relay K3B can be set as needed, or the third relay K3B can be not set. Then, the common end of the first commutation relay or the output end of the first high-impedance follower unit is the output end of the battery reverse input polarity detection unit.

[0061] Further, the first high-impedance follower unit includes a first operational amplifier. The positive input end of the first operational amplifier is electrically connected to the common end of the first commutation relay, and the negative input end and the output end of the first operational amplifier are connected together to the first input end of the comparator. The connection method of the first operational amplifier U1A is as shown in the figure and will not be elaborated here.

[0062] Further, a second high-impedance follower unit is also provided at the output end of the battery reverse input polarity detection unit. The input end of the second high-impedance follower unit is electrically connected to the output end of the first high-impedance follower unit or the common end of the third relay K3B. The output end of the second high-impedance follower unit is used to connect to the addition circuit. The second high-impedance follower unit plays a role of isolation and protection.

[0063] Further, a safety switch K1B is connected between the commutation relay and the battery load. 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.

[0064] The battery reverse input polarity detection unit can ensure that the battery or capacitor can be tested for leakage current normally regardless of whether they are connected arbitrarily.

[0065] Example 2

[0066] Refer to Figure 5 , this example discloses a method for quickly detecting the battery leakage current. The battery leakage current quick detection system described in Example 1 is adopted, and the method includes the following steps:

[0067] S1) Connect the positive and negative electrodes of the battery to the test loop, and reverse the output of the battery voltage to the test loop; the addition circuit receives the reverse input of the battery voltage and the voltage output by the core DAC unit, and the combined output is connected to the ADC unit for precise differential voltage sampling; initially, the compensation current DAC unit outputs 0;

[0068] S2) Output 1 / 2 full scale from the core DAC unit;

[0069] S3) Detect the output of the ADC unit and compare it with a set value (such as 1 / 2 full scale of the ADC unit); if the output of the ADC unit is too large or overflows, adjust the core DAC output to 1 / 4 full scale; if the output of the ADC unit is too small or underflows, adjust the core DAC output to 3 / 4 full scale;

[0070] S4) Return to step S3), detect the output of the ADC unit, compare it with the set value, and adjust the output of the core DAC unit by the dichotomy method to make the precise differential voltage sampling ADC output meet the requirements, such as being near the set value (i.e., closest to the set value, such as 1 / 2 full scale of the ADC unit). Specifically, when the core DAC outputs N, the detected ADC output value is less than the set value (such as 1 / 2 full scale of the ADC unit), and when the core DAC outputs N + 1, the detected ADC output value is greater than the set value (such as 1 / 2 full scale of the ADC unit), then take the value (N or N + 1) closer to the set value (such as 1 / 2 full scale of the ADC unit). When the ADC output reaches the requirement (such as being closest to the set value, such as 1 / 2 full scale of the ADC unit), the corresponding core DAC output is found, and the core DAC is made to maintain this output;

[0071] S5) Monitor the ADC sampling values output by the ADC unit for a period of time. When the ADC sampling values change slowly to the level of the battery self-discharge voltage change, record the current ADC sampling value X of the ADC unit;

[0072] S6) As time goes by, due to the voltage change of the battery, the ADC sampling values will change; at this time, taking the X value as the set value and the current ADC sampling value as the feedback, introduce the PID control algorithm to implement a general negative feedback control system, control the output of the compensation current DAC unit and the constant current source, and through PID parameter adjustment, make the ADC sampling values have no overshoot and no overshoot relative to the X value.

[0073] S7) When the output of the constant current source under PID control is stable, the output current of the constant current source at this time is the leakage current of the battery.

[0074] Adjust the output of the core DAC unit by the dichotomy method, specifically including: when the core DAC outputs 1 / 4 of the full scale, detect the output of the ADC unit and compare it with the set value (such as 1 / 2 of the full scale of the ADC unit); if the output of the ADC unit is too large or overflows, adjust the core DAC to output 1 / 8 of the full scale, if the output of the ADC unit is too small or underflows, adjust the core DAC to output 3 / 8 of the full scale;

[0075] When adjusting the core DAC to output 3 / 4 of the full scale, detect the output of the ADC unit and compare it with the set value (such as 1 / 2 of the full scale of the ADC unit); if the output of the ADC unit is too large or overflows, adjust the core DAC to output 5 / 8 of the full scale, if the output of the ADC unit is too small or underflows, adjust the core DAC to output 7 / 8 of the full scale, and so on.

[0076] Further, in step S4), adjust the output of the core DAC unit by the dichotomy method.

[0077] In step S4), when the output of the ADC unit meets the requirements, the output of its core DAC unit is M. After the output of the ADC unit meets the requirements in step S4), keep the output of the core DAC unit as M. After the value of M is determined, the battery voltage will still change (the influence of temperature on the battery, the voltage may increase or decrease; the influence of self-discharge leakage current, the voltage decreases). Then, setting the starting point near the set value (such as half value) can allow for the maximum variation of the battery voltage without overflowing (for example, setting it at 90%, if the battery voltage drifts slightly upwards, the voltage sampling ADC is likely to overflow). When overflow occurs, the ADC cannot output an effective voltage difference. Of course, the actual value of the set value will be determined based on statistical information (determined by the ratio of the average time of increase and the average time of decrease during the normal battery voltage test).

[0078] Further, in step S4), the output of the ADC unit meeting the requirements means that the output of the ADC unit is closest to the set value.

[0079] Preferably, the set value is 1 / 2 of the full scale of the output of the ADC unit.

[0080] Further, after arbitrarily connecting the positive and negative poles of the battery to the test loop, check the connection polarity of the battery through the battery reverse input polarity detection unit. If the connection polarity of the battery is incorrect, automatically perform input polarity commutation internally to ensure that the battery voltage is output in reverse to the next stage.

[0081] The core principle of this method for testing leakage current: the relative voltage of the ultra-high-precision constant battery current; this voltage only requires ultra-high stability and ultra-high resolution, and does not require absolute accuracy; 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.

[0082] 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 cells, soft-pack batteries, cylindrical batteries, aluminum-shell batteries, etc., and various primary batteries in square and cylindrical shapes, as well as capacitors of various technologies.

[0083] 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 rapid detection system for battery leakage current, characterized in that: It includes a core DAC unit, an ADC unit, an adder circuit, a constant current source, a compensation current DAC unit, and a processor. 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 access terminal. The first input end of the ADC unit is connected to the output end of the adder circuit. The second input end of the ADC unit is connected to the reference unit. The output end of the ADC unit is connected to the input end of the processor. The first input end of the adder circuit is connected to a second battery access terminal. The second input end of the adder circuit is connected to the output end of the core DAC unit. The first input end of the core DAC unit is connected to the second output end of the processor. The second input end of the core DAC unit is connected to the reference unit; It further includes a battery reverse input polarity detection unit. The input end of the battery reverse input polarity detection unit is connected to the second battery access terminal. The output end of the battery reverse input polarity detection unit is connected to the first input end of the adder circuit; The battery reverse input polarity detection 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 access 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 access 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 reverse input polarity detection unit. The output end of the high-impedance following unit is connected to the first input end of the adder circuit.

2. The system according to claim 1, wherein: A first low-noise processing unit is provided between the second input end of the core DAC unit and the reference unit. The input end of the first low-noise processing unit is connected to the reference unit. The output end of the first low-noise processing unit is connected to the second input end of the core DAC unit. A second low-noise processing unit is provided between the second input end of the ADC 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 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. The output end of the third low-noise processing unit is connected to the second input end of the compensation current DAC unit.

3. The system according to claim 1, wherein: A fourth low-noise processing unit is provided between the output end of the core DAC unit and the fourth input end of the adder circuit. The input end of the fourth low-noise processing unit is connected to the output end of the core DAC unit, and the output end of the fourth low-noise processing unit is connected to the fourth input end of the adder circuit.

4. The system according to claim 1, characterized in that: An amplification unit is provided between the output end of the adder circuit and the first input end of the ADC unit. The input end of the amplification unit is connected to the output end of the adder circuit, and the output end of the amplification unit is connected to the first input end of the ADC unit; the adder circuit is used to receive the reverse input of the battery voltage and the voltage output by the core DAC unit, and after combining and outputting, it is amplified by a set multiple and then connected to the ADC unit for precise differential voltage sampling.

5. A method for quickly detecting battery leakage current, characterized in that, The battery leakage current rapid detection system as described in any one of claims 1 to 4 is adopted, and it includes the following steps: S1) Connect the positive and negative electrodes of the battery to the test loop to reverse the output of the battery voltage to the test loop; S2) Output 1 / 2 full scale from the core DAC unit; S3) Detect the output of the ADC unit and compare it with the set value; if the output of the ADC unit is too large or overflows, adjust the core DAC output to 1 / 4 full scale; if the output of the ADC unit is too small or underflows, adjust the core DAC output to 3 / 4 full scale; S4) Return to step S3), adjust the output of the core DAC unit to make the output of the ADC unit meet the set requirements; S5) Monitor the ADC sampling value output by the ADC unit. When the ADC sampling value changes slowly to the level of the battery self-discharge voltage change, record the current ADC sampling value X of the ADC unit; S6) As time goes by, the ADC sampling value will change; at this time, take the X 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; S7) When the output of the constant current source controlled by PID is stable, the output current of the constant current source at this time is the leakage current of the battery.

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

7. The method according to claim 5, wherein: During the PID control process, through PID parameter adjustment, the ADC sampling value has no overshoot and no overshoot relative to the X value; step S4) adjusts the output of the core DAC unit by the dichotomy method; the output of the ADC unit meeting the requirements in step S4) means that the output of the ADC unit is closest to the set value; in step S4), when the output of the ADC unit meets the requirements, the output of its core DAC unit is M, and in step S4), after the output of the ADC unit meets the requirements, keep the output of the core DAC unit as M; The set value is 1 / 2 full scale of the output of the ADC unit.

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