Battery insulation resistance detection device

Abstract

The utility model relates to the technical field of circuits, in particular to a battery insulation resistance detection device. The device comprises an insulation resistance measuring circuit, the insulation resistance measuring circuit comprises a positive electrode measuring resistor and a negative electrode measuring resistor which are connected in series, and the positive electrode measuring resistor and the negative electrode measuring resistor are grounded through a grounding branch; the anode measuring resistor comprises a first measuring resistor R1 and a second measuring resistor R2 which are connected in series, and the second measuring resistor R2 is connected in parallel with a first switching circuit K1; the negative electrode measuring resistor comprises a third measuring resistor R3, a fourth measuring resistor R4 and a fifth measuring resistor R5 which are connected in series, and the third measuring resistor R3 is connected with a second switch circuit K2 in parallel. Through the positive and negative electrode measuring resistors connected in series and the switching circuit connected in parallel, bidirectional voltage acquisition or multi-sampling-point data is not needed, the circuit structure is simplified, and the hardware cost is reduced. And meanwhile, the problem of high voltage resistance requirement of the switch caused by introduction of an independent branch resistor is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to a battery insulation resistance detection device. Background Art

[0002] In the field of battery technology, especially in automotive and energy storage battery packs, testing battery insulation resistance is a crucial step in ensuring the safe operation of battery systems. The insulation resistance directly impacts the leakage and overall safety of the battery system, making accurate and efficient testing crucial.

[0003] However, in existing technologies, battery insulation resistance testing typically requires measuring both the positive and negative voltages of the battery pack relative to ground. This requires the system to collect bidirectional voltage data or collect voltage data at multiple sampling points. This complicates the circuit structure and increases hardware costs. Furthermore, existing insulation testing methods typically incorporate independent branch resistors when introducing known impedances, which not only increases the voltage withstand requirements for the switch but also further increases circuit complexity and cost. Utility Model Content

[0004] The utility model relates to a battery insulation resistance detection device, which can overcome certain defects of the prior art.

[0005] A battery insulation resistance detection device, characterized in that: it includes an insulation resistance measurement circuit, the insulation resistance measurement circuit includes a positive electrode measurement resistor and a negative electrode measurement resistor connected in series, the positive electrode measurement resistor is used to connect to the positive electrode of the battery to be tested, and the negative electrode measurement resistor is used to connect to the negative electrode of the battery, and the positive electrode measurement resistor and the negative electrode measurement resistor are grounded via a grounding branch;

[0006] The positive electrode measuring resistor includes a first measuring resistor R1 and a second measuring resistor R2 connected in series, the first measuring resistor R1 is used to be connected to the positive electrode of the battery; the second measuring resistor R2 is connected in parallel to a first switching circuit K1, the first switching circuit K1 is used to control the measurement path of the positive electrode measuring resistor;

[0007] The negative electrode measuring resistor includes a third measuring resistor R3, a fourth measuring resistor R4 and a fifth measuring resistor R5 connected in series, and the fifth measuring resistor R5 is used to be connected to the negative electrode of the battery; the third measuring resistor R3 is connected in parallel to a second switching circuit K2, and the second switching circuit K2 is used to control the measurement path of the negative electrode measuring resistor.

[0008] By connecting the positive and negative electrode measuring resistors in series and adding a first switch circuit K1 and a second switch circuit K2 to control the measurement path, the battery insulation resistance detection device of this utility model eliminates the need for complex bidirectional voltage acquisition or multi-sampling point voltage data acquisition, effectively reducing circuit structure complexity and hardware costs. Furthermore, through the clever use of the switching circuit, the increased switch withstand voltage and additional cost associated with the introduction of independent branch resistors are avoided.

[0009] Preferably, a third switch circuit K3 is provided on the grounding branch, and the third switch circuit K3 is used to control the connection between the insulation resistance measurement circuit and the grounding terminal.

[0010] By adding the third switch circuit K3 to the grounding branch, the grounding branch can be flexibly disconnected or connected as needed during insulation resistance measurement, thereby effectively avoiding the risk of short circuit or leakage that may occur during the measurement process.

[0011] Preferably, a control unit is further included, and the control unit is used to control the closing and opening of the first switch circuit K1, the second switch circuit K2 and the third switch circuit K3.

[0012] By introducing a control unit to precisely control the closing and opening of these switch circuits, the battery insulation resistance detection device of the present invention can flexibly form multiple measurement paths, which not only improves measurement efficiency but also ensures the accuracy and stability of the measurement results.

[0013] Preferably, the control unit controls the first switch circuit K1 and the second switch circuit K2 to be disconnected, and the third switch circuit K3 to be closed, thereby forming a first measurement path consisting of a first measuring resistor R1, a second measuring resistor R2, a third measuring resistor R3, a fourth measuring resistor R4, and a fifth measuring resistor R5 connected in series, and the first measurement path is grounded through a grounding branch.

[0014] Preferably, the control unit controls the closing of the first switch circuit K1 and the third switch circuit K3, while disconnecting the second switch circuit K2, to form a second measurement path consisting of the first measuring resistor R1, the third measuring resistor R3, the fourth measuring resistor R4 and the fifth measuring resistor R5 connected in series, and the second measurement path is grounded through the grounding branch.

[0015] Preferably, the control unit controls the closing of the second switch K2 and the third switch circuit K3, while disconnecting the second switch circuit K1, to form a third measurement path consisting of the first measuring resistor R1, the second measuring resistor R2, the fourth measuring resistor R4, and the fifth measuring resistor R5 connected in series, and the third measurement path is grounded through the grounding branch.

[0016] Preferably, the control unit controls the closing of the first switch circuit K1, the second switch circuit K2 and the third switch circuit K3 to form a fourth measurement path consisting of the first measuring resistor R1, the fourth measuring resistor R4 and the fifth measuring resistor R5 connected in series, and the fourth measurement path is grounded through the grounding branch.

[0017] Preferably, a sampling circuit is further included, and the sampling circuit is configured to obtain the voltage across the fifth measuring resistor R5 and the total voltage of the battery.

[0018] When the control unit changes the state of the switch circuit, the sampling circuit acquires the voltage across the fifth measuring resistor R5 and the total battery voltage. During the measurement process, the voltage across the measured resistor R5 is always unidirectional, eliminating the need for a bidirectional voltage acquisition circuit. Furthermore, by independently sampling the total battery voltage, the impact of total battery voltage fluctuations on insulation resistance measurement accuracy is eliminated, improving measurement speed and accuracy.

[0019] Preferably, a calculation unit is further included, which is used to calculate the positive electrode insulation resistance and the negative electrode insulation resistance by a predetermined algorithm based on the voltage across the fifth measuring resistor R5, the total voltage of the battery and the known measured resistance value obtained by the sampling circuit when the control unit controls different switching circuits to be closed and opened.

[0020] The calculation unit uses the data parameters obtained from the sampling circuit to derive the voltage between the battery's negative electrode and the ground point based on Ohm's law and the principle of circuit voltage division. The system then solves the equations to determine the insulation resistance RP and RN of the battery's positive electrode to ground. This method uses fewer measurement points and known resistance values ​​to derive the insulation resistance of the battery system to ground, simplifying circuit design and measurement processes, reducing costs, and improving measurement accuracy.

[0021] Preferably, the resistance values ​​of the first measuring resistor R1 , the second measuring resistor R2 , the third measuring resistor R3 , the fourth measuring resistor R4 and the fifth measuring resistor R5 do not exceed 500Ω / V.

[0022] By properly designing the resistance range of the measuring resistor (not exceeding 500Ω / V), the withstand voltage requirement for the switch can be reduced while ensuring measurement accuracy, further improving the safety and reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a circuit diagram of a battery insulation resistance detection device in this embodiment 1.

[0024] Figure 2 For Figure 1 Based on the above, the equivalent circuit diagram is shown when K1 and K3 are closed and K2 is opened.

[0025] Figure 3 For Figure 1 Based on the above, the equivalent circuit diagram is shown when K2 and K3 are closed and K1 is disconnected.

[0026] Figure 4 For Figure 1 Based on the above, the equivalent circuit diagram when K1, K2 and K3 are closed. DETAILED DESCRIPTION

[0027] In order to further understand the content of the utility model, the utility model is described in detail in conjunction with the embodiments. It should be understood that the embodiments are only for explaining the utility model and are not intended to limit the scope of the utility model.

[0028] Example 1

[0029] like Figure 1 A battery insulation resistance detection device is shown, characterized in that it includes an insulation resistance measurement circuit, the insulation resistance measurement circuit including a positive electrode measurement resistor and a negative electrode measurement resistor connected in series, the positive electrode measurement resistor is used to connect to the positive electrode of the battery to be tested, and the negative electrode measurement resistor is used to connect to the negative electrode of the battery, and the positive electrode measurement resistor and the negative electrode measurement resistor are grounded via a grounding branch;

[0030] The positive electrode measuring resistor includes a first measuring resistor R1 and a second measuring resistor R2 connected in series, the first measuring resistor R1 is used to be connected to the positive electrode of the battery; the second measuring resistor R2 is connected in parallel to a first switching circuit K1, the first switching circuit K1 is used to control the measurement path of the positive electrode measuring resistor;

[0031] The negative electrode measuring resistor includes a third measuring resistor R3, a fourth measuring resistor R4 and a fifth measuring resistor R5 connected in series, and the fifth measuring resistor R5 is used to be connected to the negative electrode of the battery; the third measuring resistor R3 is connected in parallel to a second switching circuit K2, and the second switching circuit K2 is used to control the measurement path of the negative electrode measuring resistor.

[0032] Specifically, the switch circuit K1 plays a role in controlling the measurement path of the positive electrode measurement resistance during the measurement process, that is, whether to include the second measurement resistor R2 in the measurement circuit is selected as needed. A second switch circuit K2 is connected in parallel at both ends of the third measurement resistor R3. This switch circuit K2 also selects whether to include the third measurement resistor R3 in the measurement circuit as needed. During measurement, by controlling the closing and opening of the switch circuits K1, K2 and the grounding switch K3, the resistance combination in the measurement circuit can be changed, thereby realizing the measurement of the positive and negative poles of the battery to ground resistance. This embodiment realizes the measurement of the positive and negative poles of the battery to ground resistance by connecting the positive and negative poles of the battery in series and the switch circuit in parallel, greatly simplifying the circuit structure. At the same time, by using the first switch circuit K1 and the second switch circuit K2, the switch withstand voltage increase and additional cost problems caused by the introduction of independent branch resistors are avoided.

[0033] In this embodiment, a third switch circuit K3 is provided on the grounding branch, and the third switch circuit K3 is used to control the connection between the insulation resistance measurement circuit and the grounding terminal.

[0034] Specifically, the third switch circuit K3 is provided on the grounding branch and is responsible for controlling the connection between the insulation resistance measurement circuit and the ground terminal, so that the circuit can be safely grounded when needed to ensure the accuracy and safety of the measurement.

[0035] In this embodiment, a control unit is further included, and the control unit is used to control the closing and opening of the first switch circuit K1, the second switch circuit K2 and the third switch circuit K3.

[0036] Specifically, the control unit controls the opening and closing of the first, second, and third switching circuits K1, K2, and K3. By precisely controlling the opening and closing of these switching circuits, the control unit selects different measurement paths within the insulation resistance measurement circuit, thereby completing insulation resistance measurements. By precisely controlling the opening and closing of the switching circuits, the control unit reduces the withstand voltage requirements of the switching elements, improving the safety and reliability of the device.

[0037] In this embodiment, the control unit controls the first switch circuit K1 and the second switch circuit K2 to be disconnected, and the third switch circuit K3 to be closed, thereby forming a first measurement path consisting of the first measuring resistor R1, the second measuring resistor R2, the third measuring resistor R3, the fourth measuring resistor R4, and the fifth measuring resistor R5 connected in series, and the first measurement path is grounded through the grounding branch.

[0038] In this embodiment, the control unit controls the first switch circuit K1 and the third switch circuit K3 to be closed, while the second switch circuit K2 is opened, thereby forming a second measurement path consisting of the first measuring resistor R1, the third measuring resistor R3, the fourth measuring resistor R4, and the fifth measuring resistor R5 connected in series. The second measurement path is grounded through the grounding branch.

[0039] In this embodiment, the control unit controls the closing of the second switch K2 and the third switch circuit K3, while disconnecting the second switch circuit K1, thereby forming a third measurement path consisting of the first measuring resistor R1, the second measuring resistor R2, the fourth measuring resistor R4, and the fifth measuring resistor R5 connected in series, and the third measurement path is grounded through the grounding branch.

[0040] In this embodiment, the control unit controls the closing of the first switch circuit K1, the second switch circuit K2, and the third switch circuit K3 to form a fourth measurement path consisting of the first measurement resistor R1, the fourth measurement resistor R4, and the fifth measurement resistor R5 connected in series, and the fourth measurement path is grounded through the grounding branch.

[0041] In this embodiment, a sampling circuit is further included, and the sampling circuit is configured to obtain the voltage across the fifth measuring resistor R5 and the total voltage of the battery.

[0042] In this embodiment, a calculation unit is further included, which is used to calculate the positive electrode insulation resistance and the negative electrode insulation resistance using a predetermined algorithm based on the voltage across the fifth measuring resistor R5, the total voltage of the battery, and the known measured resistance value obtained by the sampling circuit when the control unit controls the closing and opening of different switching circuits.

[0043] Specifically, known resistors R1, R2, R3, R4, and R5 are introduced between the positive and negative electrodes of the battery and the ground. The measurement steps and calculation process of this embodiment are as follows:

[0044] S1: The control unit controls the closing of the third switch circuit K3 and the opening of the first switch circuit K1 and the second switch circuit K2; the sampling circuit measures the voltage across the fifth measuring resistor R5 and the total voltage of the battery The calculation unit calculates the equivalent voltage between the negative electrode of the battery and the ground point based on the voltage division principle. , then use the equivalent circuit and Ohm's law to establish the first equation for the positive electrode insulation resistance Rp and the negative electrode insulation resistance Rn: × ; ;

[0045] S2: In Figure 1On the basis of, the control unit controls the closing of the first switch circuit K1 and the third switch circuit K3, and the opening of the second switch circuit K2. The equivalent circuit diagram is as follows: Figure 2 As shown; the sampling circuit measures the voltage across the fifth measuring resistor R5 and the total voltage of the battery The calculation unit calculates the equivalent voltage between the negative electrode of the battery and the ground point based on the voltage division principle. , and then use the equivalent circuit and Ohm's law to establish the second equation for Rp and Rn: × ; ;

[0046] S3: Figure 1 On the basis of, the control unit controls the closing of the second switch circuit K2 and the third switch circuit K3, and the opening of the first switch circuit K1. The equivalent circuit diagram is as follows: Figure 3 As shown; the sampling circuit measures the voltage across the fifth measuring resistor R5 and the total voltage of the battery The calculation unit calculates the equivalent voltage between the negative electrode of the battery and the ground point based on the voltage division principle. , and then use the equivalent circuit and Ohm's law to establish the third equation for Rp and Rn: × ; ;

[0047] S4: Figure 1 On the basis of the above, the control unit controls the closing of the first switch circuit K1, the second switch circuit K2 and the third switch circuit K3, and the equivalent circuit diagram is as follows: Figure 4 As shown; the sampling circuit measures the voltage across the fifth measuring resistor R5 and the total voltage of the battery The calculation unit calculates the equivalent voltage between the negative electrode of the battery and the ground point based on the voltage division principle. , and then use the equivalent circuit and Ohm's law to establish the fourth equation for Rp and Rn: × ; ;

[0048] In the above steps S1, S2, S3, and S4, the accurate resistance values ​​of the positive electrode insulation resistance Rp and the negative electrode insulation resistance Rn can be calculated by using step 123, step 124, and step 134 in combination.

[0049] Specifically, the first switching circuit K1, the second switching circuit K2, and the third switching circuit K3 in the embodiment can be flexibly implemented using at least one of a mechanical relay, a MOS transistor, or an optocoupler relay, depending on actual needs. In practical applications, the choice of switching circuit depends on the specific application requirements and circuit conditions. For example, in applications requiring high voltage and high current, a mechanical relay may be more suitable; in applications requiring high-speed response and low power consumption, a MOS transistor may be more ideal; and in applications requiring high electrical isolation, an optocoupler relay is a good choice.

[0050] In this embodiment, the control unit precisely controls the opening and closing of different switching circuits to form multiple measurement paths. Each measurement path provides different information about the insulation resistance of the battery's positive and negative electrodes. Combining the voltage data acquired by the sampling circuit with the known measured resistance values, the calculation unit can use a predetermined algorithm to accurately calculate the positive and negative insulation resistances Rp and Rn.

[0051] Secondly, by performing multiple measurements and calculations, using different equivalent circuits and equations established using Ohm's law, a more comprehensive understanding of the battery insulation resistance can be obtained. This multiple measurement method helps reduce errors and improves measurement accuracy and efficiency.

[0052] In this embodiment, the resistance values ​​of the first measuring resistor R1 , the second measuring resistor R2 , the third measuring resistor R3 , the fourth measuring resistor R4 and the fifth measuring resistor R5 do not exceed 500Ω / V.

[0053] Specifically, when measuring battery insulation resistance, the selection of the measuring resistor value is crucial. A resistance value that is too large may result in an excessive voltage drop across the resistor, affecting the accuracy of the voltage measurement. On the other hand, a resistance value that is too small may result in excessive current flow, increasing system power consumption and potentially posing safety risks. Therefore, after comprehensive consideration, this embodiment selects a resistance range of no more than 500Ω / V to ensure measurement accuracy and system safety.

[0054] It is easy to understand that those skilled in the art can combine, split, reorganize, etc. the embodiments of the present application based on one or several embodiments provided in the present application to obtain other embodiments, and these embodiments do not exceed the scope of protection of the present application.

[0055] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The embodiments shown are only part of the embodiments of the present invention, and the actual structure is not limited to them. Therefore, if a person skilled in the art is inspired by the above and designs a structure and embodiment similar to the technical solution without creatively designing it without departing from the inventive purpose of the present invention, it shall fall within the scope of protection of the present invention.

Claims

1. A battery insulation resistance detection device, characterized in that: The insulation resistance measurement circuit includes a positive electrode measurement resistor and a negative electrode measurement resistor connected in series, the positive electrode measurement resistor is used to connect to the positive electrode of the battery to be tested, and the negative electrode measurement resistor is used to connect to the negative electrode of the battery, and the positive electrode measurement resistor and the negative electrode measurement resistor are grounded through a grounding branch; The positive electrode measuring resistor includes a first measuring resistor R1 and a second measuring resistor R2 connected in series, the first measuring resistor R1 is used to be connected to the positive electrode of the battery; the second measuring resistor R2 is connected in parallel to a first switching circuit K1, the first switching circuit K1 is used to control the measurement path of the positive electrode measuring resistor; The negative electrode measuring resistor includes a third measuring resistor R3, a fourth measuring resistor R4 and a fifth measuring resistor R5 connected in series, and the fifth measuring resistor R5 is used to be connected to the negative electrode of the battery; the third measuring resistor R3 is connected in parallel to a second switching circuit K2, and the second switching circuit K2 is used to control the measurement path of the negative electrode measuring resistor.

2. The insulation resistance detection device according to claim 1, wherein: A third switch circuit K3 is provided on the grounding branch, and the third switch circuit K3 is used to control the connection between the insulation resistance measurement circuit and the grounding terminal.

3. A battery insulation resistance detection device according to claim 2, characterized in that: The system further comprises a control unit, which is used to control the closing and opening of the first switch circuit K1 , the second switch circuit K2 and the third switch circuit K3 .

4. The insulation resistance detection device according to claim 3, wherein: Under the control of the control unit, the first switch circuit K1 and the second switch circuit K2 are disconnected, and the third switch circuit K3 is closed at the same time, forming a first measurement path composed of the first measuring resistor R1, the second measuring resistor R2, the third measuring resistor R3, the fourth measuring resistor R4, and the fifth measuring resistor R5 connected in series, and the first measurement path is grounded through the grounding branch.

5. The insulation resistance detection device according to claim 3, wherein: Under the control of the control unit, the first switch circuit K1 and the third switch circuit K3 are closed, and the second switch circuit K2 is opened at the same time, forming a second measurement path composed of the first measuring resistor R1, the third measuring resistor R3, the fourth measuring resistor R4 and the fifth measuring resistor R5 connected in series, and the second measurement path is grounded through the grounding branch.

6. The insulation resistance detection device according to claim 3, wherein: Under the control of the control unit, the second switch K2 and the third switch circuit K3 are closed, and the second switch circuit K1 is opened at the same time, forming a third measurement path composed of the first measuring resistor R1, the second measuring resistor R2, the fourth measuring resistor R4, and the fifth measuring resistor R5 connected in series, and the third measurement path is grounded through the grounding branch.

7. The insulation resistance detection device according to claim 3, wherein: Under the control of the control unit, the first switch circuit K1, the second switch circuit K2 and the third switch circuit K3 are closed to form a fourth measurement path consisting of the first measuring resistor R1, the fourth measuring resistor R4 and the fifth measuring resistor R5 connected in series, and the fourth measurement path is grounded through the grounding branch.

8. The insulation resistance detection device according to claim 1, wherein: The system further includes a sampling circuit configured to obtain the voltage across the fifth measuring resistor R5 and the total voltage of the battery.

9. A battery insulation resistance detection device according to claim 8, characterized in that: It also includes a calculation unit, which is used to calculate the positive electrode insulation resistance and the negative electrode insulation resistance through a predetermined algorithm based on the voltage across the fifth measuring resistor R5, the total voltage of the battery, and the known measured resistance value obtained by the sampling circuit when the control unit controls different switching circuits to be closed and opened.

10. The battery insulation resistance detection device according to claim 1, characterized in that: The resistance values ​​of the first measuring resistor R1 , the second measuring resistor R2 , the third measuring resistor R3 , the fourth measuring resistor R4 and the fifth measuring resistor R5 do not exceed 500Ω / V.

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