Method and device for realizing self-adaption of insulation detection period of battery pack

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a method for realizing battery pack insulation detection period self-adaption, which comprises the following steps of: building an insulation detection circuit, enabling the insulation detection precision of the circuit to reach a preset range, acquiring voltage data of the circuit in a sampling range in a segmented manner, and screening proper data. And calculating the resistance value of the insulation resistor of the insulation detection circuit so as to realize irregular insulation detection. According to the invention, insulation leakage can be identified in time on the premise that the insulation resistance detection precision is ensured, and the situation of missing alarm of insulation leakage or false alarm of insulation leakage is prevented. In addition, the invention also provides a device for realizing the self-adaption of the insulation detection period of the battery pack.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a method and a device for realizing self-adaptation of a battery pack insulation detection cycle. Background Art

[0002] The existing technology can only perform insulation detection on the battery periodically. Among them, fixed period detection will greatly reduce the detection accuracy of insulation resistance. At the same time, setting the fixed period too short or too long will cause misjudgment of detection, and it is impossible to flexibly and reasonably obtain the insulation leakage detection situation in the battery pack. Therefore, it is urgent to propose a new technical solution to solve the above problems. Summary of the invention

[0003] One of the purposes of the present invention is to address the deficiencies of the prior art and provide a method for realizing self-adaptation of the insulation detection cycle of a battery pack, which has high detection accuracy for insulation resistance and prevents the occurrence of underreporting or false reporting of insulation leakage.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A method for realizing self-adaptation of a battery pack insulation detection cycle comprises the following steps:

[0006] S1. Build an insulation detection circuit so that the insulation detection accuracy of the circuit reaches a preset range;

[0007] S2, collecting voltage data of the circuit within a sampling range in sections, and screening suitable voltage data;

[0008] S3, selecting a threshold value according to the actual operating voltage range of the battery pack so that the difference between the maximum value and the minimum value of the screened voltage data is smaller than the threshold value;

[0009] S4, extract the last sampled voltage value in S2, and calculate the insulation resistance value of the insulation detection circuit to realize irregular insulation detection.

[0010] Furthermore, the S1 includes:

[0011] S1-1, build an insulation detection circuit, the insulation detection circuit has an upper bridge arm switch, an upper bridge arm voltage-dividing resistor, an upper bridge arm sampling resistor, a lower bridge arm switch, a lower bridge arm voltage-dividing resistor, a lower bridge arm sampling resistor, a positive-to-ground Y capacitor, a negative-to-ground Y capacitor, a positive-to-ground insulation resistor, and a negative-to-ground insulation resistor;

[0012] S1-2, close the upper bridge arm switch and the lower bridge arm switch, and collect the upper bridge arm sampling voltage corresponding to the upper bridge arm sampling resistor and the lower bridge arm sampling voltage corresponding to the lower bridge arm sampling resistor;

[0013] S1-3. Calculate the positive voltage to ground and the negative voltage to ground, and ensure that the sum of the positive voltage to ground and the negative voltage to ground is greater than 95% of the total voltage of the insulation detection circuit.

[0014] Further, the S1 includes: making the upper bridge arm voltage-dividing resistor and the lower bridge arm voltage-dividing resistor equal and both are R, making the upper bridge arm sampling resistor and the lower bridge arm sampling resistor equal and both are R';

[0015]

[0016] Furthermore, the S1 includes: connecting the positive Y capacitor to ground in parallel with the positive insulation resistor to ground, and connecting the negative Y capacitor to ground in parallel with the negative insulation resistor to ground.

[0017] Furthermore, S2 includes:

[0018] S2-1, collecting a number of sampling data of the upper bridge arm sampling voltage and the lower bridge arm sampling voltage, and dividing the plurality of sampling data of the upper bridge arm sampling voltage and the lower bridge arm sampling voltage into a segments, where a is greater than 3;

[0019] S2-2. Calculate the average value of each segment of data, select the maximum and minimum values ​​based on these average values, and calculate the difference between the maximum and minimum values.

[0020] Furthermore, the step S3 further includes: when the difference between the maximum value and the minimum value of the screened voltage data is not less than the threshold value, repeating the step S2.

[0021] Furthermore, the threshold selected in S3 is 1 mV to 30 mV.

[0022] Furthermore, in S4, the resistance values ​​of the positive insulation resistance to ground and the negative insulation resistance to ground are obtained through the upper bridge arm voltage divider resistor, the lower bridge arm voltage divider resistor, the upper bridge arm sampling resistor, the lower bridge arm sampling resistor, the upper bridge arm sampling voltage and the lower bridge arm sampling voltage.

[0023] Furthermore, the step S2-1 also includes collecting a plurality of sampling data of each segment within a time period of 0.1s to 1s.

[0024] The second object of the present invention is to provide a device for realizing self-adaptation of the insulation detection cycle of a battery pack, comprising:

[0025] A voltage acquisition module is used to access a preset position of an insulation detection circuit to collect a required voltage value;

[0026] A determination and comparison module, electrically connected to the voltage acquisition module, for determining and comparing the voltage values ​​of different acquisition units of the voltage acquisition module to achieve cycle adaptation of detection;

[0027] The calculation module is electrically connected to the voltage acquisition module and the determination and comparison module respectively, and is used to calculate the insulation resistance value of the insulation detection circuit.

[0028] The beneficial effects of the present invention are: 1) The main purpose of the present invention is to timely identify insulation leakage under the premise of ensuring the accuracy of insulation resistance detection, and also to prevent underreporting or false reporting of insulation leakage. The detection concept is more scientific and effective than the existing technology, will not cause misjudgment of detection, and the detection result is more accurate and reliable; 2) The present invention will change the periodic detection according to changes in the measurement environment, thereby ensuring the safe operation of the battery pack; 3) The detection process of the present invention is closely linked, rigorously conceived, and highly logical, thereby effectively improving the accuracy of insulation resistance detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a flow chart of the steps of the method of the present invention.

[0030] Figure 2 The insulation detection circuit constructed for the present invention.

[0031] Figure 3 Schematic diagram of a charging curve of a Y capacitor in the present invention.

[0032] Figure 4 It is a schematic diagram of the relationship between voltage data and time of the present invention.

[0033] Figure 5 Schematic diagram of the module of the device of the present invention. DETAILED DESCRIPTION

[0034] If certain words are used in the specification and claims to refer to specific components, those skilled in the art should understand that manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" is an open term and should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0035] In the invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0036] In the present invention, the inventor uses the balanced bridge method as an example to illustrate how to affect the accuracy of insulation resistance: the inventor found that when the positive insulation resistance to ground and the negative insulation resistance to ground of the battery pack voltage platform are detected, since the size of the positive Y capacitor to ground and the negative Y capacitor to ground of the battery pack will be affected by the aging of the capacitor itself and the type and number of external devices, if the detection is carried out at a fixed period, the insulation resistance detection accuracy will be greatly reduced. On the one hand, if the fixed period is set too short, the sampling voltage will be extracted in advance before the Y capacitor is fully charged, so that the insulation resistance will produce a relatively large error, which is easy to misreport insulation leakage or omission of insulation leakage; on the other hand, if the fixed period is set too long, although the Y capacitor is fully charged and the sampling voltage is accurate, once there is a leakage, the leakage fault is not reported in time, which will increase the risk of life and reduce the operating safety of the battery. In addition, if the fixed period is fixed, the sampling voltage data may be collected during the rapid discharge or rapid charging of the battery pack, and the polarization reaction of the battery cell in this process will reduce the accuracy of insulation resistance detection.

[0037] In order to solve the above problems, the following Figures 1 to 5 The present invention is further described in detail with reference to the following specific embodiments, but is not intended to limit the present invention.

[0038] Example 1

[0039] A method for realizing self-adaptation of a battery pack insulation detection cycle comprises the following steps:

[0040] S1. Build an insulation detection circuit to ensure that the insulation detection accuracy of the circuit reaches the preset range;

[0041] S1-1. Build an insulation detection circuit with a balanced bridge, wherein the insulation detection circuit has an upper bridge arm switch, an upper bridge arm voltage-dividing resistor, an upper bridge arm sampling resistor, a lower bridge arm switch, a lower bridge arm voltage-dividing resistor, a lower bridge arm sampling resistor, a positive Y capacitor to ground, a negative Y capacitor to ground, a positive insulation resistor to ground, and a negative insulation resistor to ground, wherein the positive Y capacitor to ground is connected in parallel with the positive insulation resistor to ground, and the negative Y capacitor to ground is connected in parallel with the negative insulation resistor to ground;

[0042] S1-2, close the upper bridge arm switch and the lower bridge arm switch, and collect the upper bridge arm sampling voltage corresponding to the upper bridge arm sampling resistor and the lower bridge arm sampling voltage corresponding to the lower bridge arm sampling resistor;

[0043] S1-3, calculate and obtain the positive voltage to ground and the negative voltage to ground, and ensure that the sum of the positive voltage to ground and the negative voltage to ground is greater than 95% of the total voltage of the insulation detection circuit. Specifically, make the upper bridge arm voltage divider resistor and the lower bridge arm voltage divider resistor equal and both are R, and make the upper bridge arm sampling resistor and the lower bridge arm sampling resistor equal and both are R';

[0044]

[0045] S2, collecting the voltage data of the circuit within the sampling range in sections, and selecting appropriate voltage data;

[0046] S2-1, collecting a number of sampling data of the upper bridge arm sampling voltage and the lower bridge arm sampling voltage, respectively dividing the sampling data of the upper bridge arm sampling voltage and the lower bridge arm sampling voltage into a segments, a is greater than 3, and the multiple sampling data of each segment are collected within 0.1s to 1s;

[0047] S2-2, calculate the average value of each segment of data, filter out the maximum and minimum values ​​according to the average values, and calculate the difference between the maximum and minimum values;

[0048] S3, selecting a threshold value according to the actual operating voltage range of the battery pack so that the difference between the maximum value and the minimum value of the screened voltage data is less than the threshold value, and when the difference between the maximum value and the minimum value of the screened voltage data is not less than the threshold value, repeating step S2;

[0049] S4, extract the last sampled voltage value in S2, and calculate the insulation resistance value of the insulation detection circuit to realize irregular insulation detection.

[0050] Preferably, the threshold selected in S3 is 1 mV to 30 mV.

[0051] Preferably, in S4, the resistance values ​​of the positive insulation resistance to ground and the negative insulation resistance to ground are obtained through the upper bridge arm voltage divider resistor, the lower bridge arm voltage divider resistor, the upper bridge arm sampling resistor, the lower bridge arm sampling resistor, the upper bridge arm sampling voltage and the lower bridge arm sampling voltage.

[0052] like Figure 2As shown, in the insulation detection circuit with a balanced bridge, S1 is the upper arm switch, R1 is the upper arm voltage divider resistor, R2 is the upper arm sampling resistor, S2 is the lower arm switch, R3 is the lower arm voltage divider resistor, and R4 is the lower arm sampling resistor. Among them, R1 = R3, R2 = R4. C1 is the positive Y capacitor to ground, C2 is the negative Y capacitor to ground, Rp is the positive insulation resistance to ground, and Rn is the negative insulation resistance to ground. The insulation resistance can be calculated by comparing two known voltage divider resistors, two known sampling resistors, the upper arm sampling voltage, and the lower arm sampling voltage.

[0053] Specifically, first close the upper bridge arm switch S1 and the lower bridge arm switch S2, collect the upper bridge arm sampling voltage corresponding to the upper bridge arm sampling resistor R2 and the lower bridge arm sampling voltage corresponding to the lower bridge arm sampling resistor R4, and then obtain the positive voltage to ground and the negative voltage to ground from the upper bridge arm sampling voltage and the lower bridge arm sampling voltage. Figure 3 From the Y capacitor charging curve, it can be seen that when the voltage reaches 95%, the Y capacitor tends to be fully charged. At this time, the basic insulation detection accuracy can be guaranteed. Then, it is judged whether (positive voltage to ground + negative voltage to ground) is greater than 95% of the total voltage. If so, the next step is started. If not, it will continue to wait for the Y capacitor to be fully charged. In addition, in order to adjust the insulation detection accuracy, 95.5%, 96%, 96.5%, 97%, 98% of the total voltage can also be taken as the judgment value.

[0054] Next, the upper bridge arm sampling voltage and the lower bridge arm sampling voltage are divided into a segments, each segment contains b sampling data. For example, when a is 10, the collected voltage data is divided into 10 segments for a total of 1S, each segment has 10 data for a total of 100ms, and then each segment of b sampling data is averaged to obtain a segment of data x1, x2, ..., xa. From x1, x2, ..., xa, first calculate the maximum and minimum values ​​​​among them, and then obtain the difference △x between the maximum and minimum values ​​​​.

[0055] After that, it is determined whether the difference △x between the maximum value and the minimum value is less than the threshold value. If so, the data screening is completed. If not, the screening continues. The threshold selection is selected according to the actual situation of the project (related to ADC resolution and accuracy, reference voltage, voltage divider resistor, sampling resistor, etc.), and different thresholds can be selected according to different battery pack operating voltage ranges.

[0056] After the voltage data is screened, xa is used as the sampled voltage value. According to the sampled voltage value, the known voltage divider resistance and sampling resistance, the resistance values ​​of the positive insulation resistance Rp to ground and the negative insulation resistance Rn to ground are obtained.

[0057] according to Figure 1 The sampling data collection process in the steps may remember the interval time between S101 to S401, or remember the interval time between S101 to S801.

[0058] Similarly, when the upper arm switch or the lower arm switch is disconnected, the sampled voltage value will be collected in the same way after the interval time. According to the sampled voltage value, the known voltage divider resistance and sampling resistance, the resistance values ​​of the positive insulation resistance Rp to ground and the negative insulation resistance Rn to ground can be obtained.

[0059] Therefore, the present invention first allows the total voltage (positive voltage to ground + negative voltage to ground) to be greater than 95%, and the Y capacitor to be in a full state to ensure basic insulation detection accuracy; then the sampled voltage is segmented, and the difference between the maximum and minimum values ​​between the threshold and each segment of data is compared to consider that the battery cell is in a stable state; substitute the formula to calculate the insulation resistance. Different from the prior art, this solution selects sampled data that tends to be stable to substitute into the formula. The inventor found that this is the only way to effectively ensure that the method can obtain the correct value. At the same time, if the Y capacitor connected to the battery system changes randomly, variable period detection is very necessary, so the detection method of this solution has strong versatility.

[0060] Example 2

[0061] A device for realizing self-adaptation of battery pack insulation detection cycle, such as Figure 5 As shown, including:

[0062] A voltage acquisition module is used to access a preset position of an insulation detection circuit to collect a required voltage value;

[0063] A determination and comparison module, electrically connected to the voltage acquisition module, for determining and comparing the voltage values ​​of different acquisition units of the voltage acquisition module to achieve cycle adaptation of detection;

[0064] The calculation module is electrically connected to the voltage acquisition module and the determination and comparison module respectively, and is used to calculate the insulation resistance value of the insulation detection circuit.

[0065] Through the coordination of multiple modules of the insulation detection device and the interlocking and rigorous logical design of the entire detection process, the accuracy of insulation resistance detection can be effectively improved. At the same time, the entire device and detection method will change the periodic detection according to changes in the measurement environment, thereby effectively ensuring the safe operation of the battery pack.

[0066] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for realizing self-adaptation of battery pack insulation detection cycle, characterized in that: The following steps are involved: S1. Build an insulation detection circuit so that the insulation detection accuracy of the circuit reaches a preset range; S2, collecting voltage data of the circuit within a sampling range in sections, and screening suitable voltage data; S3, selecting a threshold value according to the actual operating voltage range of the battery pack so that the difference between the maximum value and the minimum value of the screened voltage data is smaller than the threshold value; S4, extract the last sampled voltage value in S2, and calculate the insulation resistance value of the insulation detection circuit to realize irregular insulation detection.

2. The method for realizing self-adaptation of battery pack insulation detection cycle according to claim 1, characterized in that: The S1 includes: S1-1, build an insulation detection circuit, the insulation detection circuit has an upper bridge arm switch, an upper bridge arm voltage-dividing resistor, an upper bridge arm sampling resistor, a lower bridge arm switch, a lower bridge arm voltage-dividing resistor, a lower bridge arm sampling resistor, a positive-to-ground Y capacitor, a negative-to-ground Y capacitor, a positive-to-ground insulation resistor, and a negative-to-ground insulation resistor; S1-2, close the upper bridge arm switch and the lower bridge arm switch, and collect the upper bridge arm sampling voltage corresponding to the upper bridge arm sampling resistor and the lower bridge arm sampling voltage corresponding to the lower bridge arm sampling resistor; S1-3. Calculate the positive voltage to ground and the negative voltage to ground, and ensure that the sum of the positive voltage to ground and the negative voltage to ground is greater than 95% of the total voltage of the insulation detection circuit.

3. The method for realizing self-adaptation of battery pack insulation detection cycle according to claim 2, characterized in that: The upper bridge arm voltage-dividing resistor and the lower bridge arm voltage-dividing resistor are equal and both are R, and the upper bridge arm sampling resistor and the lower bridge arm sampling resistor are equal and both are R'; 4. The method for realizing self-adaptation of battery pack insulation detection cycle according to claim 2, characterized in that: The positive Y capacitor to ground is connected in parallel with the positive insulation resistor to ground, and the negative Y capacitor to ground is connected in parallel with the negative insulation resistor to ground.

5. The method for realizing self-adaptation of battery pack insulation detection cycle according to any one of claims 2 to 4, characterized in that: The S2 includes: S2-1, collecting a number of sampling data of the upper bridge arm sampling voltage and the lower bridge arm sampling voltage, and dividing the plurality of sampling data of the upper bridge arm sampling voltage and the lower bridge arm sampling voltage into a segments, where a is greater than 3; S2-2. Calculate the average value of each segment of data, select the maximum and minimum values ​​based on these average values, and calculate the difference between the maximum and minimum values.

6. The method for realizing self-adaptation of battery pack insulation detection cycle according to any one of claims 1 to 4, characterized in that: The step S3 further includes: when the difference between the maximum value and the minimum value of the screened voltage data is not less than the threshold value, repeating the step S2.

7. The method for realizing self-adaptation of battery pack insulation detection cycle according to any one of claims 1 to 4, characterized in that: The threshold selected in S3 is 1 mV to 30 mV.

8. The method for realizing self-adaptation of battery pack insulation detection cycle according to any one of claims 2 to 4, characterized in that: In S4, the resistance values ​​of the positive insulation resistance to ground and the negative insulation resistance to ground are obtained through the upper bridge arm voltage dividing resistor, the lower bridge arm voltage dividing resistor, the upper bridge arm sampling resistor, the lower bridge arm sampling resistor, the upper bridge arm sampling voltage and the lower bridge arm sampling voltage.

9. The method for realizing self-adaptation of battery pack insulation detection cycle according to claim 5, characterized in that: The step S2-1 also includes collecting a plurality of sampling data of each segment within a period of 0.1s to 1s.

10. A device for realizing self-adaptation of battery pack insulation detection cycle, characterized in that: include: A voltage acquisition module is used to access a preset position of an insulation detection circuit to acquire a required voltage value; A determination and comparison module, electrically connected to the voltage acquisition module, for determining and comparing the voltage values ​​of different acquisition units of the voltage acquisition module to achieve cycle adaptation of detection; The calculation module is electrically connected to the voltage acquisition module and the determination and comparison module respectively, and is used to calculate the insulation resistance value of the insulation detection circuit.

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