Insulation electric leakage detection device

Abstract

The utility model discloses an insulation electric leakage detection device comprising an insulation electric leakage detection circuit and a controller BMSMCU, and the controller BMSMCU is respectively connected with the insulation electric leakage detection circuit and a load / PCS device. The insulation leakage detection circuit comprises a battery pack, a plurality of resistors, a plurality of switches and a reference ground. The first resistor R1 and the second resistor R2 are connected in series and then connected with the positive electrode of the battery pack and the reference ground. A battery pack anode analog quantity sampling interface ADx is arranged between the first resistor R1 and the second resistor R2; a fifth resistor R5 is connected in series with a first switch SW1 and is connected with the anode of the battery pack and the reference ground; the third resistor R3 and the fourth resistor R4 are connected in series and then connected to the reference ground and the negative electrode of the battery pack; a battery pack negative electrode analog quantity sampling interface ADy is arranged between the third resistor R3 and the fourth resistor R4; the sixth resistor R6 is connected in series with a second switch SW2 and then is connected to the negative electrode of the battery pack and the reference ground.

Description

Technical Field

[0001] The utility model relates to the technical field of insulation leakage detection, in particular to an insulation leakage detection device. Background Art

[0002] Insulation leakage detection is an important function in the battery management system, mainly responsible for detecting the magnitude of the insulation leakage resistance of the positive or negative electrode of the battery pack system relative to the reference ground, so as to determine whether the battery pack system is in a leakage state.

[0003] A core index of the insulation leakage detection function is the accuracy of collecting the voltage values of a pair of voltage dividing resistors at the positive or negative electrode of the battery pack relative to the reference ground in the insulation leakage detection circuit. To ensure the accuracy of the voltage division value, in addition to using voltage dividing resistors with higher accuracy, it is also necessary to well process the capacitance introduced by the PCS (Power Conversion System, energy storage converter) or load equipment into the positive and negative electrode circuits of the battery pack system.

[0004] To ensure the accuracy of insulation leakage detection, it is necessary to remove or reduce this capacitance, so as to balance the accuracy and speed of insulation leakage detection. Currently, this capacitance cannot be removed, and it is necessary to perform staggered calculation through a control algorithm and simultaneously take into account the corresponding filtering algorithm to realize the detection of the insulation leakage resistance.

[0005] In addition, for the unbalanced bridge insulation circuit, when the leakage resistances of the positive and negative electrodes of the battery pack to the reference ground are the same, there is also a problem that the accuracy of the voltage division value is difficult to meet the calculation requirements. Especially when the total voltage range of the battery pack to be considered is relatively wide, these problems are particularly obvious. For example, in a 1500V high-voltage system, assuming that the leakage resistances of the positive and negative electrodes of the battery pack to the reference ground are both 300KΩ, according to the working principle of the unbalanced bridge, if a resistor is not artificially connected to offset the voltages of the positive and negative electrodes of the battery pack relative to the reference ground, then the sampled voltage division values of the positive and negative electrodes of the battery pack are very close at this time. In this scenario, it is exactly the same as the scenario where the positive and negative electrodes of the resistor group do not leak electricity, resulting in the inability to solve when the bilateral leakage resistances are the same. Summary of the Utility Model

[0006] The utility model aims at the problems and deficiencies existing in the prior art, and provides a novel insulation leakage detection device.

[0007] The utility model solves the above technical problems through the following technical solutions:

[0008] The present utility model provides an insulation leakage detection device, which includes an insulation leakage detection circuit and a controller BMS_MCU. The controller BMS_MCU is respectively connected to the insulation leakage detection circuit and a load / PCS device;

[0009] The insulation leakage detection circuit includes a battery pack, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first switch SW1, a second switch SW2, a fourth switch SW4, a fifth switch SW5, and a reference ground;

[0010] The negative pole of the first resistor R1 is connected to the positive pole of the second resistor R2. The positive pole of the first resistor R1 is connected to the positive pole of the battery pack, and the negative pole of the second resistor R2 is connected to the reference ground. A battery pack positive pole analog quantity sampling interface ADx is provided between the negative pole of the first resistor R1 and the positive pole of the second resistor R2;

[0011] The positive pole of the fifth resistor R5 is connected to the positive pole of the battery pack in series with the first switch SW1, and the negative pole of the fifth resistor R5 is connected to the reference ground;

[0012] The negative pole of the third resistor R3 is connected to the positive pole of the fourth resistor R4. The positive pole of the third resistor R3 is connected to the reference ground. A battery pack negative pole analog quantity sampling interface ADy is provided between the negative pole of the third resistor R3 and the positive pole of the fourth resistor R4;

[0013] The negative pole of the fourth resistor R4 is connected to the negative pole of the battery pack. The negative pole of the sixth resistor R6 is connected to the negative pole of the battery pack in series with the second switch SW2, and the positive pole of the sixth resistor R6 is connected to the reference ground;

[0014] The positive pole of the load / PCS device is connected to the positive pole of the battery pack in series with the fourth switch SW4, the negative pole of the load / PCS device is connected to the negative pole of the battery pack in series with the fifth switch SW5, and the ground wire of the load / PCS device is connected to the reference ground.

[0015] Preferably, the insulation leakage detection circuit further includes a seventh resistor R7 and a third switch SW3. The positive pole of the seventh resistor R7 is connected to the positive pole of the battery pack in series with the third switch SW3, and the negative pole of the seventh resistor R7 is connected to the reference ground.

[0016] Preferably, the controller BMS_MCU controls the closing and opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 respectively.

[0017] Preferably, the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 are all normally open contacts of contactors or relays. The controller BMS_MCU controls the closing and opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 by controlling the power-on and power-off of the coils of the corresponding contactors or relays.

[0018] Preferably, the controller BMS_MCU is connected to the battery pack positive analog acquisition interface ADx and the battery pack negative analog acquisition interface ADy through a control line, and the controller BMS_MCU receives the data from the battery pack positive analog acquisition interface ADx and the battery pack negative analog acquisition interface ADy.

[0019] Preferably, the controller BMS_MCU is connected to the load / PCS device through a communication line to receive the communication data of the load / PCS device; the controller BMS_MCU is connected to the load / PCS device through a signal feedback line to obtain the feedback signal of the load / PCS device.

[0020] The positive and progressive effects of the present utility model are as follows:

[0021] The insulation leakage detection device provided by the present utility model, the insulation leakage detection circuit includes a battery pack, a plurality of resistors, a plurality of switches, and a reference ground; the first resistor R1 and the second resistor R2 are connected in series and then connected to the positive electrode of the battery pack and the reference ground; a battery pack positive analog sampling interface ADx is provided between the first resistor R1 and the second resistor R2; the fifth resistor R5 is connected in series with the first switch SW1 and connected to the positive electrode of the battery pack and the reference ground; the seventh resistor R7 is connected in series with the third switch SW3 and then connected to the positive electrode of the battery pack and the reference ground; the third resistor R3 and the fourth resistor R4 are connected in series and then connected to the reference ground and the negative electrode of the battery pack; a battery pack negative analog sampling interface ADy is provided between the third resistor R3 and the fourth resistor R4; the sixth resistor R6 is connected in series with the second switch SW2 and then connected to the negative electrode of the battery pack and the reference ground; the voltage-dividing resistors are reasonably arranged, so that the circuit can be fully compatible with high-voltage systems in a wide voltage range of 500V to 1500V; the insulation leakage detection circuit focuses on estimating the insulation resistance in scenarios where the leakage situation is relatively serious, improving the detection accuracy and detection speed; for the situation where the positive electrode and the negative electrode of the battery pack are both leaking to the reference ground at the same time, the state of the seventh resistor R7 connected to the positive electrode of the battery pack and the reference ground is switched through the third switch SW3, and the leakage resistance during bilateral leakage is quickly analyzed. Description of the Drawings

[0022] Figure 1 is the schematic diagram of the insulation leakage detection circuit of the embodiment of the present utility model;

[0023] Figure 2 This is the control block diagram of the insulation leakage detection device according to the embodiment of the present invention. Specific embodiments

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Please refer to Figure 1 and Figure 2 , this embodiment provides an insulation leakage detection device, including an insulation leakage detection circuit and a controller BMS_MCU. The controller BMS_MCU is respectively connected to the insulation leakage detection circuit and the load / PCS device;

[0026] The insulation leakage detection circuit includes a battery pack, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first switch SW1, a second switch SW2, a third switch SW3, a fourth switch SW4, a fifth switch SW5 and a reference ground;

[0027] The negative electrode of the first resistor R1 is connected to the positive electrode of the second resistor R2. The positive electrode of the first resistor R1 is connected to the positive electrode of the battery pack, and the negative electrode of the second resistor R2 is connected to the reference ground. A battery pack positive electrode analog quantity sampling interface ADx is provided between the negative electrode of the first resistor R1 and the positive electrode of the second resistor R2;

[0028] The positive electrode of the fifth resistor R5 is connected to the positive electrode of the battery pack in series with the first switch SW1, and the negative electrode of the fifth resistor R5 is connected to the reference ground. The positive electrode of the seventh resistor R7 is connected to the positive electrode of the battery pack in series with the third switch SW3, and the negative electrode of the seventh resistor R7 is connected to the reference ground;

[0029] The negative electrode of the third resistor R3 is connected to the positive electrode of the fourth resistor R4. The positive electrode of the third resistor R3 is connected to the reference ground. A battery pack negative electrode analog quantity sampling interface ADy is provided between the negative electrode of the third resistor R3 and the positive electrode of the fourth resistor R4;

[0030] The negative electrode of the fourth resistor R4 is connected to the negative electrode of the battery pack. The negative electrode of the sixth resistor R6 is connected to the negative electrode of the battery pack in series with the second switch SW2, and the positive electrode of the sixth resistor R6 is connected to the reference ground;

[0031] The positive electrode of the load / PCS device is connected to the positive electrode of the battery pack after being serially connected with a fourth switch SW4, and the negative electrode of the load / PCS device is connected to the negative electrode of the battery pack after being serially connected with a fifth switch SW5. The ground wire of the load / PCS device is connected to the reference ground;

[0032] The capacitance of the positive electrode of the load / PCS device relative to the reference ground is a first capacitor C1, the capacitance of the negative electrode of the load / PCS device relative to the reference ground is a second capacitor C2, the leakage resistance of the positive electrode of the battery pack relative to the reference ground is a first leakage resistance Rx, and the leakage resistance of the negative electrode of the battery pack relative to the reference ground is a second leakage resistance Ry;

[0033] The controller BMS_MCU receives the data from the analog quantity acquisition interface ADx of the positive electrode of the battery pack and the analog quantity acquisition interface ADy of the negative electrode of the battery pack, and the controller BMS_MCU controls the closing and opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 respectively; the controller BMS_MCU receives the communication data and the working feedback signal of the load / PCS device.

[0034] In some embodiments, the controller BMS_MCU is connected to the analog quantity acquisition interface ADx of the positive electrode of the battery pack and the analog quantity acquisition interface ADy of the negative electrode of the battery pack through control lines.

[0035] In some embodiments, the controller BMS_MCU is connected to the load / PCS device through a communication line to receive the communication data of the load / PCS device; the controller BMS_MCU is connected to the load / PCS device through a signal feedback line to obtain the feedback signal of the load / PCS device.

[0036] In some embodiments, the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 are all normally open contacts of contactors or relays, and the controller BMS_MCU controls the closing and opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 by controlling the energization and de-energization of the coils of the corresponding contactors or relays.

[0037] To better understand the technical solution provided by the embodiments of the present invention, the process of performing insulation leakage detection using this insulation leakage detection device will be further described below.

[0038] The leakage resistance of the positive electrode of the battery pack relative to the reference ground is a first leakage resistance Rx, the leakage resistance of the negative electrode of the battery pack relative to the reference ground is a second leakage resistance Ry, the capacitance of the positive electrode of the load / PCS device relative to the reference ground is a first capacitor C1, and the capacitance of the negative electrode of the load / PCS device relative to the reference ground is a second capacitor C2. The insulation leakage detection includes the following steps:

[0039] S1: Determine whether the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage division values of the analog acquisition interface ADx of the battery pack positive electrode and the analog acquisition interface ADy of the battery pack negative electrode. If they do, control the fourth switch SW4 and the fifth switch SW5 to open simultaneously. If they don't, control the fourth switch SW4 and the fifth switch SW5 to close simultaneously;

[0040] S2: Control the first switch SW1 and the second switch SW2 to close, and the third switch SW3 to open; Obtain the voltage division values of the analog acquisition interface ADx of the battery pack positive electrode and the analog acquisition interface ADy of the battery pack negative electrode at this time, which are the first positive electrode voltage division value Up1 and the first negative electrode voltage division value Un1 respectively; At this time, there is the following equation in the insulation leakage detection circuit. In the following formula, " / / " represents calculating the parallel resistance:

[0041]

[0042] S3: Control the first switch SW1 to close, and the second switch SW2 and the third switch SW3 to open; Obtain the voltage division values of the analog acquisition interface ADx of the battery pack positive electrode and the analog acquisition interface ADy of the battery pack negative electrode at this time, which are the second positive electrode voltage division value Up2 and the second negative electrode voltage division value Un2 respectively; At this time, there is the following equation in the insulation leakage detection circuit:

[0043]

[0044] S4: Control the first switch SW1 to open, the second switch SW2 to close, and the third switch SW3 to open. Obtain the voltage division values of the analog acquisition interface ADx of the battery pack positive electrode and the analog acquisition interface ADy of the battery pack negative electrode at this time, which are the third positive electrode voltage division value Up3 and the third negative electrode voltage division value Un3 respectively; At this time, there is the following equation in the insulation leakage detection circuit:

[0045]

[0046] S5: Control the first switch SW1, the second switch SW2, and the third switch SW3 to close. Obtain the voltage division values of the analog acquisition interface ADx of the battery pack positive electrode and the analog acquisition interface ADy of the battery pack negative electrode at this time, which are the fourth positive electrode voltage division value Up4 and the fourth negative electrode voltage division value Un4 respectively; At this time, there is the following equation in the insulation leakage detection circuit:

[0047]

[0048] S6: Calculate the first leakage resistance Rx and the second leakage resistance Ry.

[0049] Set the resistance values of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 to satisfy the following relationships:

[0050] R1 = R4 (5)

[0051] R2 = R3 (6)

[0052] R5 = R6 = R7 (7)

[0053] When the fourth switch SW4 and the fifth switch SW5 are closed simultaneously, combining formulas (1)-(3) and (5)-(7), the first leakage resistor Rx and the second leakage resistor Ry are calculated by the following formulas:

[0054]

[0055] where, Up1 is the first positive voltage division value, Un1 is the first negative voltage division value; Up2 is the second positive voltage division value, Un2 is the second negative voltage division value; Up3 is the third positive voltage division value, Un3 is the third negative voltage division value; R3 is the resistance value of the third resistor; R4 is the resistance value of the fourth resistor; R5 is the resistance value of the fifth resistor.

[0056] When the fourth switch SW4 and the fifth switch SW5 are opened simultaneously, combining formulas (3)-(7), the first leakage resistor Rx and the second leakage resistor Ry can be calculated by the following formulas:

[0057]

[0058] E = ((R5 × (R3 + R4)) / (R3 + R4 + R5)) (11)

[0059]

[0060] where, Up3 is the third positive voltage division value, Un3 is the third negative voltage division value; Up4 is the fourth positive voltage division value, Un4 is the fourth negative voltage division value; R3 is the resistance value of the third resistor; R4 is the resistance value of the fourth resistor; R5 is the resistance value of the fifth resistor.

[0061] When calculating the leakage resistance using the unbalanced bridge of the above circuit, it is necessary to distinguish different leakage situations. When the values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack are relatively close, the formulas (10)-(12) should be used to solve the leakage resistances Rx and Ry. When the values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack are relatively close, it is very easy to cause calculation overflow when calculating with the formulas (8)-(9). This is caused by the sampling precision error and is very difficult to solve. To reduce the influence of the error on the calculation, the best way is to widen the values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack, and reconnect a hypothetical leakage resistance between the positive electrode of the battery pack and the reference ground, that is, close the third switch SW3 and connect the seventh resistor R7; or connect a hypothetical leakage resistance between the negative electrode of the battery pack and the reference ground. In this way, it can be ensured that when the leakage resistances Rx and Ry are relatively close, the values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack will have an obvious distinction, thereby reducing the interference of the sampling error.

[0062] In some embodiments, to determine the influence of the first capacitor C1 and the second capacitor C2 on the voltage division values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack, it includes: switching the states of the first switch SW1, the second switch SW2, or the third switch SW3, and checking the changes in the voltage division values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack during the state switching process. If the voltage division value changes, it indicates that the first capacitor C1 and the second capacitor C2 do not affect the measurement of the voltage division values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack; if the voltage division value remains unchanged, it indicates that the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage division values of the analog acquisition interface ADx of the positive electrode of the battery pack and the analog acquisition interface ADy of the negative electrode of the battery pack.

[0063] In summary, the insulation leakage detection device provided by the present utility model, the insulation leakage detection circuit includes a battery pack, multiple resistors, multiple switches and a reference ground; the first resistor R1 and the second resistor R2 are connected in series and then connected to the positive electrode of the battery pack and the reference ground; a battery pack positive electrode analog quantity sampling interface ADx is provided between the first resistor R1 and the second resistor R2; the fifth resistor R5 is connected in series with the first switch SW1 and connected to the positive electrode of the battery pack and the reference ground; the seventh resistor R7 is connected in series with the third switch SW3 and then connected to the positive electrode of the battery pack and the reference ground; the third resistor R3 and the fourth resistor R4 are connected in series and then connected to the reference ground and the negative electrode of the battery pack; a battery pack negative electrode analog quantity sampling interface ADy is provided between the third resistor R3 and the fourth resistor R4; the sixth resistor R6 is connected in series with the second switch SW2 and then connected to the negative electrode of the battery pack and the reference ground; the voltage-dividing resistors are reasonably arranged so that the circuit can be fully compatible with high-voltage systems in a wide voltage range of 500V to 1500V; the insulation leakage detection circuit focuses on estimating the insulation resistance in scenarios where the leakage situation is relatively serious, improving the detection accuracy and detection speed; for the situation where both the positive electrode and the negative electrode of the battery pack leak to the reference ground, the state of the seventh resistor R7 connected to the positive electrode of the battery pack and the reference ground is switched through the third switch SW3, and the leakage resistance during bilateral leakage is quickly analyzed.

[0064] Although the specific implementation manners of the present utility model have been described above, those skilled in the art should understand that these are only examples. The protection scope of the present utility model is defined by the appended claims. Without departing from the principle and essence of the present utility model, those skilled in the art can make various changes or modifications to these implementation manners, but these changes and modifications all fall within the protection scope of the present utility model.

Claims

1. An insulation leakage detection device, characterized in that, It includes an insulation leakage detection circuit and a controller BMS_MCU, and the controller BMS_MCU is respectively connected to the insulation leakage detection circuit and the load / PCS device; The insulation leakage detection circuit includes a battery pack, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first switch SW1, a second switch SW2, a fourth switch SW4, a fifth switch SW5, and a reference ground; The negative pole of the first resistor R1 is connected to the positive pole of the second resistor R2, the positive pole of the first resistor R1 is connected to the positive pole of the battery pack, and the negative pole of the second resistor R2 is connected to the reference ground; a battery pack positive pole analog quantity sampling interface ADx is provided between the negative pole of the first resistor R1 and the positive pole of the second resistor R2; The positive pole of the fifth resistor R5 is connected to the positive pole of the battery pack in series after the first switch SW1, and the negative pole of the fifth resistor R5 is connected to the reference ground; The negative pole of the third resistor R3 is connected to the positive pole of the fourth resistor R4, the positive pole of the third resistor R3 is connected to the reference ground; a battery pack negative pole analog quantity sampling interface ADy is provided between the negative pole of the third resistor R3 and the positive pole of the fourth resistor R4; The negative pole of the fourth resistor R4 is connected to the negative pole of the battery pack; the negative pole of the sixth resistor R6 is connected to the negative pole of the battery pack in series after the second switch SW2, and the positive pole of the sixth resistor R6 is connected to the reference ground; The positive pole of the load / PCS device is connected to the positive pole of the battery pack in series after the fourth switch SW4, the negative pole of the load / PCS device is connected to the negative pole of the battery pack in series after the fifth switch SW5, and the ground wire of the load / PCS device is connected to the reference ground.

2. The insulation leakage detection device according to claim 1, characterized in that, The insulation leakage detection circuit further includes a seventh resistor R7 and a third switch SW3, the positive pole of the seventh resistor R7 is connected to the positive pole of the battery pack in series after the third switch SW3, and the negative pole of the seventh resistor R7 is connected to the reference ground.

3. The insulation leakage detection device according to claim 2, characterized in that, The controller BMS_MCU respectively controls the closing and opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5.

4. The insulation leakage detection device according to claim 3, characterized in that, The first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 are all normally open contacts of contactors or relays, and the controller BMS_MCU controls the closing and opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, and the fifth switch SW5 by controlling the energization and de-energization of the coils of the corresponding contactors or relays.

5. The insulation leakage detection device according to claim 1, wherein, The controller BMS_MCU is connected to the positive analog acquisition interface ADx of the battery pack and the negative analog acquisition interface ADy of the battery pack through a control line, and the controller BMS_MCU receives data from the positive analog acquisition interface ADx of the battery pack and the negative analog acquisition interface ADy of the battery pack.

6. The insulation leakage detection device according to claim 1, characterized in that, The controller BMS_MCU is connected to the load / PCS device through a communication line to receive communication data from the load / PCS device; the controller BMS_MCU is connected to the load / PCS device through a signal feedback line to obtain a feedback signal from the load / PCS device.

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