Battery management system insulation leakage detection device and detection method

Abstract

The invention discloses a battery management system insulation electric leakage detection device which comprises an insulation electric leakage detection circuit and a controller BMSMCU, and the controller BMSMCU is 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; a seventh resistor R7 is connected in series with a third switch SW3 and then connected with 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 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 present invention relates to the technical field of insulation leakage detection, and in particular to an insulation leakage detection device and a detection method for a battery management system. Background Art

[0002] Insulation leakage detection is an important function in the battery management system. It is mainly responsible for detecting 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 indicator of the insulation leakage detection function is the accuracy of the voltage value 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-dividing value, in addition to using high-precision voltage-dividing resistors, it is also necessary to properly handle the capacitance of the positive and negative circuits of the battery pack system introduced by the PCS (Power Conversion System, energy storage converter) or load equipment.

[0004] In order to ensure the accuracy of insulation leakage detection, it is necessary to remove or reduce this capacitor so as to take into account both the accuracy and speed of insulation leakage detection. Currently, this capacitor cannot be removed, and it is necessary to use a control algorithm to calculate the peak while taking into account the corresponding filtering algorithm to realize the detection of insulation leakage resistance.

[0005] In addition, the unbalanced bridge insulation circuit also faces the problem that the voltage divider accuracy is difficult to meet the calculation requirements when the leakage resistance of the positive and negative electrodes of the battery pack to the reference ground is the same value. This is especially true when the total voltage range of the battery pack to be considered is relatively wide. For example, in a 1500V high-voltage system, assuming that the leakage resistance of the positive and negative electrodes of the battery pack to the reference ground is 300KΩ, according to the working principle of the unbalanced bridge, if a resistor is not manually connected to offset the voltage of the positive and negative electrodes of the battery pack relative to the reference ground, then the sampled voltage divider value of the positive electrode of the battery pack and the sampled voltage divider value of the negative electrode of the battery pack are very close. In this scenario, the leakage resistance of the positive and negative electrodes of the resistor group is exactly the same as the scenario where there is no leakage, resulting in the inability to solve the problem when the bilateral leakage resistance is the same. Summary of the invention

[0006] In view of the problems and shortcomings of the prior art, the present invention provides a novel insulation leakage detection device and detection method for a battery management system.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] The present invention provides an insulation leakage detection device for a battery management system, comprising an insulation leakage detection circuit and a controller BMS_MCU, wherein the controller BMS_MCU is connected to the insulation leakage detection circuit and a load / PCS device respectively;

[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 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;

[0010] 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;

[0011] The positive electrode of the fifth resistor R5 is connected in series with the first switch SW1 and then connected to the positive electrode of the battery pack, 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 in series with the third switch SW3 and then connected to the positive electrode of the battery pack, and the negative electrode of the seventh resistor R7 is connected to the reference ground;

[0012] The negative electrode of the third resistor R3 is connected to the positive electrode of the fourth resistor R4, and 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;

[0013] 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 in series with the second switch SW2 and then connected to the negative electrode of the battery pack, and the positive electrode of the sixth resistor R6 is connected to the reference ground;

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

[0015] The capacitance of the positive electrode of the load / PCS device relative to the reference ground is a first capacitance C1, the capacitance of the negative electrode of the load / PCS device relative to the reference ground is a second capacitance 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;

[0016] The controller BMS_MCU receives data from the battery pack positive pole analog quantity acquisition interface ADx and the battery pack negative pole analog quantity acquisition interface ADy, and 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; the controller BMS_MCU receives communication data and working feedback signals of the load / PCS device.

[0017] Preferably, the controller BMS_MCU is connected to the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy through a control line.

[0018] Preferably, the controller BMS_MCU is connected to the load / PCS device via a communication line to receive communication data of the load / PCS device; the controller BMS_MCU is connected to the load / PCS device via a signal feedback line to obtain a feedback signal of the load / PCS device.

[0019] 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, 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 power on and off of the coils of the corresponding contactors or relays.

[0020] Based on the same concept, the present invention also provides a detection method for an insulation leakage detection device of a battery management system, wherein 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 capacitance C1, and the capacitance of the negative electrode of the load / PCS device relative to the reference ground is a second capacitance C2, comprising the following steps:

[0021] Determine whether the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage division value of the positive analog quantity acquisition interface ADx of the battery pack and the negative analog quantity acquisition interface ADy of the battery pack, and if so, control the fourth switch SW4 and the fifth switch SW5 to be disconnected at the same time; if not, control the fourth switch SW4 and the fifth switch SW5 to be closed at the same time;

[0022] Control the first switch SW1 and the second switch SW2 to be closed, and the third switch SW3 to be open; obtain the voltage division values ​​of the positive analog quantity acquisition interface ADx and the negative analog quantity acquisition interface ADy of the battery pack at this time, which are the positive first voltage division value Up1 and the negative first voltage division value Un1 respectively;

[0023] Control the first switch SW1 to be closed, and the second switch SW2 and the third switch SW3 to be open; obtain the voltage division values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy at this time, which are the positive electrode second voltage division value Up2 and the negative electrode second voltage division value Un2 respectively;

[0024] Control the first switch SW1 to be turned off, the second switch SW2 to be turned on, and the third switch SW3 to be turned off, and obtain the voltage division values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy at this time, which are the positive electrode third voltage division value Up3 and the negative electrode third voltage division value Un3 respectively;

[0025] Control the first switch SW1, the second switch SW2 and the third switch SW3 to close, obtain the voltage division values ​​of the battery pack positive pole analog quantity acquisition interface ADx and the battery pack negative pole analog quantity acquisition interface ADy at this time, which are the positive pole fourth voltage division value Up4 and the negative pole fourth voltage division value Un4 respectively; calculate the first leakage resistance Rx and the second leakage resistance Ry.

[0026] Preferably, 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 satisfy the following relationship:

[0027] R1=R4

[0028] R2=R3

[0029] R5=R6=R7

[0030] When the fourth switch SW4 and the fifth switch SW5 are closed at the same time, the first leakage resistance Rx and the second leakage resistance Ry are calculated by the following formula:

[0031]

[0032] Among them, Up1 is the first voltage division value of the positive electrode, and Un1 is the first voltage division value of the negative electrode; Up2 is the second voltage division value of the positive electrode, and Un2 is the second voltage division value of the negative electrode; Up3 is the third voltage division value of the positive electrode, and Un3 is the third voltage division value of the negative electrode; 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.

[0033] Preferably, 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 satisfy the following relationship:

[0034] R1=R4

[0035] R2=R3

[0036] R5=R6=R7

[0037] When the fourth switch SW4 and the fifth switch SW5 are turned off at the same time, the first leakage resistance Rx and the second leakage resistance Ry can be calculated by the following formula:

[0038]

[0039] E=((R5×(R3+R4)) / (R3+R4+R5))

[0040]

[0041] Among them, 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.

[0042] Preferably, judging the influence of the first capacitor C1 and the second capacitor C2 on the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy includes: switching the state of the first switch SW1, the second switch SW2 or the third switch SW3, and checking the change of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy during the state switching process. If the voltage divider value changes, it means that the first capacitor C1 and the second capacitor C2 do not affect the measurement of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy; if the voltage divider value remains unchanged, it means that the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy.

[0043] The positive and progressive effects of the present invention are:

[0044] The present invention provides a battery management system insulation leakage detection device and detection method, 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 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 to connect the positive electrode of the battery pack and the reference ground; the seventh resistor R7 is connected in series with the third switch SW3 to connect 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 connected to the reference ground and the negative electrode of the battery pack; the third resistor R3 and the first resistor R4 are connected in series and connected to the reference ground and the negative electrode of the battery pack; A battery pack negative pole analog sampling interface ADy is provided between the four resistors R4; the sixth resistor R6 is connected in series with the second switch SW2 and then connected to the negative pole of the battery pack and the reference ground; the voltage divider resistor is reasonably set so that the circuit can be fully compatible with the high voltage system with a wide voltage range of 500V to 1500V; the insulation leakage detection circuit focuses on the insulation resistance estimation in scenarios with serious leakage, thereby improving the detection accuracy and speed; in the case where the positive pole and the negative pole of the battery pack leak to the reference ground at the same time, the seventh resistor R7 is switched to the state of connecting the positive pole of the battery pack and the reference ground through the third switch SW3, so as to quickly analyze the leakage resistance during bilateral leakage.

[0045] Furthermore, a judgment is added on the influence of the access of the PCS / load device to the reference ground capacitors, the first capacitor C1 and the second capacitor C2, on the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy. It is determined whether the PCS / load device needs to be cut off based on the influence, and different calculation methods are used to improve the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of an insulation leakage detection circuit according to an embodiment of the present invention;

[0047] Figure 2 This is a control block diagram of an insulation leakage detection device for a battery management system according to an embodiment of the present invention;

[0048] Figure 3 This is a flow chart of a detection method of an insulation leakage detection device for a battery management system according to an embodiment of the present invention;

[0049] Figure 4 The values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy in the insulation leakage detection circuit of the present invention are affected by the first capacitor C1 and the second capacitor C2 Figure 1 ;

[0050] Figure 5The values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy in the insulation leakage detection circuit of the present invention are affected by the first capacitor C1 and the second capacitor C2 Figure 2 ;

[0051] Figure 6 The values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy in the insulation leakage detection circuit of the present invention are affected by the first capacitor C1 and the second capacitor C2 Figure 3 . DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] See also Figure 1 and Figure 2 , this embodiment provides a battery management system insulation leakage detection device, including an insulation leakage detection circuit and a controller BMS_MCU, the controller BMS_MCU is connected to the insulation leakage detection circuit and the load / PCS device respectively;

[0054] 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;

[0055] 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;

[0056] The positive electrode of the fifth resistor R5 is connected in series with the first switch SW1 and then connected to the positive electrode of the battery pack, 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 in series with the third switch SW3 and then connected to the positive electrode of the battery pack, and the negative electrode of the seventh resistor R7 is connected to the reference ground;

[0057] The negative electrode of the third resistor R3 is connected to the positive electrode of the fourth resistor R4, and 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;

[0058] 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 after being connected in series with the second switch SW2, and the positive electrode of the sixth resistor R6 is connected to the reference ground;

[0059] The positive electrode of the load / PCS device is connected in series with the fourth switch SW4 and then connected to the positive electrode of the battery pack, the negative electrode of the load / PCS device is connected in series with the fifth switch SW5 and then connected to the negative electrode of the battery pack, and the ground wire of the load / PCS device is connected to the reference ground;

[0060] The capacitance of the positive electrode of the load / PCS device relative to the reference ground is the first capacitance C1, the capacitance of the negative electrode of the load / PCS device relative to the reference ground is the second capacitance C2, the leakage resistance of the positive electrode of the battery pack relative to the reference ground is the first leakage resistance Rx, and the leakage resistance of the negative electrode of the battery pack relative to the reference ground is the second leakage resistance Ry;

[0061] The controller BMS_MCU receives data from the battery pack positive pole analog quantity acquisition interface ADx and the battery pack negative pole analog quantity acquisition interface ADy, 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 communication data and working feedback signals of the load / PCS device.

[0062] In some embodiments, the controller BMS_MCU connects the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy through a control line.

[0063] In some embodiments, the controller BMS_MCU is connected to the load / PCS device via a communication line to receive communication data of the load / PCS device; the controller BMS_MCU is connected to the load / PCS device via a signal feedback line to obtain a feedback signal of the load / PCS device.

[0064] 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 power on and off of the coils of the corresponding contactors or relays.

[0065] See also Figure 3The present invention also provides a detection method for an insulation leakage detection device of a battery management system, wherein 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 capacitance C1, and the capacitance of the negative electrode of the load / PCS device relative to the reference ground is a second capacitance C2, comprising the following steps:

[0066] S1: Determine whether the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage division value of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy, if so, control the fourth switch SW4 and the fifth switch SW5 to be disconnected at the same time, if not, control the fourth switch SW4 and the fifth switch SW5 to be closed at the same time;

[0067] 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 battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy at this time, which are the positive electrode first voltage division value Up1 and the negative electrode first voltage division value Un1 respectively; at this time, the insulation leakage detection circuit has the following equation, and the " / / " in the following formula represents the calculation of the parallel resistance:

[0068]

[0069] 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 battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy at this time, which are the positive electrode second voltage division value Up2 and the negative electrode second voltage division value Un2 respectively; at this time, the insulation leakage detection circuit has the following equation:

[0070]

[0071] S4: Control the first switch SW1 to be disconnected, the second switch SW2 to be closed, and the third switch SW3 to be disconnected, and obtain the voltage division values ​​of the positive analog quantity acquisition interface ADx and the negative analog quantity acquisition interface ADy of the battery pack at this time, which are the positive third voltage division value Up3 and the negative third voltage division value Un3 respectively; at this time, the insulation leakage detection circuit has the following equation:

[0072]

[0073] S5: Control the first switch SW1, the second switch SW2 and the third switch SW3 to close, and obtain the voltage division values ​​of the positive analog quantity acquisition interface ADx and the negative analog quantity acquisition interface ADy of the battery pack at this time, which are the fourth voltage division value Up4 of the positive electrode and the fourth voltage division value Un4 of the negative electrode respectively; at this time, the following equation exists in the insulation leakage detection circuit:

[0074]

[0075] S6: Calculate the first leakage resistance Rx and the second leakage resistance Ry.

[0076] 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 are set to satisfy the following relationship:

[0077] R1=R4 (5)

[0078] R2=R3 (6)

[0079] R5=R6=R7 (7)

[0080] When the fourth switch SW4 and the fifth switch SW5 are closed at the same time, the first leakage resistance Rx and the second leakage resistance Ry are calculated by the following formula in combination with formulas (1)-(3) and (5)-(7):

[0081]

[0082] Among them, Up1 is the first voltage division value of the positive electrode, and Un1 is the first voltage division value of the negative electrode; Up2 is the second voltage division value of the positive electrode, and Un2 is the second voltage division value of the negative electrode; Up3 is the third voltage division value of the positive electrode, and Un3 is the third voltage division value of the negative electrode; 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.

[0083] When the fourth switch SW4 and the fifth switch SW5 are turned off at the same time, the first leakage resistance Rx and the second leakage resistance Ry can be calculated by the following formulas in combination with formulas (3)-(7):

[0084]

[0085] E = ((R5×(R3+R4)) / (R3+R4+R5)) (11)

[0086]

[0087] Among them, 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.

[0088] When using the unbalanced bridge of the above circuit to calculate the leakage resistance, it is necessary to distinguish different leakage conditions. When it is detected that the values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy are close, formulas (10)-(12) should be used to solve the leakage resistances Rx and Ry. When the values ​​of 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 are close, it is easy to cause the calculation to be out of bounds when calculating in formulas (8)-(9). This is caused by the sampling accuracy error and is difficult to solve. In order to reduce the impact of the error on the calculation, the best way is to separate the values ​​of 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 reconnect a hypothetical leakage resistor between the positive electrode of the battery pack and the reference ground, that is, close the third switch SW3 to connect the seventh resistor R7; or connect a hypothetical leakage resistor between the negative electrode of the battery pack and the reference ground. In this way, it can be ensured that when the values ​​of the leakage resistance Rx and Ry are close, the values ​​of 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 will be clearly distinguished, thereby reducing the interference of the sampling error.

[0089] In some embodiments, determining the influence of the first capacitor C1 and the second capacitor C2 on the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy includes: switching the state of the first switch SW1, the second switch SW2 or the third switch SW3, and checking the changes in the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy during the state switching process. If the voltage divider value changes, it means that the first capacitor C1 and the second capacitor C2 do not affect the measurement of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy; if the voltage divider value remains unchanged, it means that the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy.

[0090] In a specific implementation, the state of the first switch SW1, the second switch SW2 or the third switch SW3 is switched to check the change of the voltage division value of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy during the state switching process. Figure 4 or Figure 5 As shown in , changes occur, indicating that the first capacitor C1 and the second capacitor C2 do not affect the measurement of the voltage division value of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy; switch the state of the first switch SW1, the second switch SW2 or the third switch SW3, and check the changes in the voltage division value of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy during the state switching process. The voltage division value is as follows Figure 6As shown in , it remains unchanged, indicating that the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage division value of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy.

[0091] The following verification test is carried out. For the voltage range of 600V to 1500V, the leakage resistance of different resistance values ​​is simulated input between the positive electrode of the battery pack and the reference ground (referred to as positive terminal single-side leakage) and the negative electrode of the battery pack and the reference ground (referred to as negative terminal single-side leakage). The calculated insulation leakage resistance is compared with the actual minimum leakage resistance. The results are shown in the following Table 1 Test Results Comparison Table:

[0092] Test results comparison table

[0093]

[0094]

[0095] Under the resistance values ​​R1=R4=5.1KΩ, R2=R3=3060KΩ, R5=R6=R7=800KΩ selected in the test, within a wide voltage range, in the case of single-sided leakage at the positive end or single-sided leakage at the negative end, when the leakage resistance is less than 3000KΩ, the insulation estimation accuracy is very high, and the error is less than 5KΩ; in the case of double-sided leakage, when the double-sided leakage resistance is not completely equal, when the leakage resistance is less than 1000KΩ, the insulation estimation accuracy error is less than 20KΩ; for the double-sided leakage case, when the double-sided leakage resistance is completely equal, when the leakage resistance is less than 100KΩ, the insulation estimation accuracy error is less than 2KΩ. By adjusting the values ​​of the selected resistors R1 / R2 / R5, the accuracy errors of these calculation results can be even smaller.

[0096] In summary, the present invention provides a battery management system insulation leakage detection device and detection method, 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 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 to connect the positive electrode of the battery pack and the reference ground; the seventh resistor R7 is connected in series with the third switch SW3 to connect 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 connected to the reference ground and the negative electrode of the battery pack; the third resistor R 3 and the fourth resistor R4 are provided with a battery pack negative electrode analog quantity sampling interface ADy; 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 divider resistor is reasonably set so that the circuit can be fully compatible with the high voltage system with a wide voltage range of 500V to 1500V; the insulation leakage detection circuit focuses on the insulation resistance estimation in the scenario where the leakage is relatively serious, thereby improving the detection accuracy and detection speed; in the case where the positive electrode and the negative electrode of the battery pack leak to the reference ground at the same time, the state of connecting the positive electrode of the battery pack and the reference ground is switched by the third switch SW3 to quickly analyze the leakage resistance during bilateral leakage.

[0097] Furthermore, the present invention adds a judgment on the influence of the access of the PCS / load device to the reference ground capacitors, the first capacitor C1 and the second capacitor C2, on the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy, determines whether it is necessary to cut off the PCS / load device based on the influence, and adopts different calculation methods to improve the detection accuracy.

[0098] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A battery management system 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 connected to the insulation leakage detection circuit and the load / PCS device respectively; 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; 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; The positive electrode of the fifth resistor R5 is connected in series with the first switch SW1 and then connected to the positive electrode of the battery pack, 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 in series with the third switch SW3 and then connected to the positive electrode of the battery pack, and the negative electrode of the seventh resistor R7 is connected to the reference ground; The negative electrode of the third resistor R3 is connected to the positive electrode of the fourth resistor R4, and 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; 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 in series with the second switch SW2 and then connected to the negative electrode of the battery pack, and the positive electrode of the sixth resistor R6 is connected to the reference ground; The positive electrode of the load / PCS device is connected in series with the fourth switch SW4 and then connected to the positive electrode of the battery pack, the negative electrode of the load / PCS device is connected in series with the fifth switch SW5 and then connected to the negative electrode of the battery pack, and the ground wire of the load / PCS device is connected to the reference ground; The capacitance of the positive electrode of the load / PCS device relative to the reference ground is a first capacitance C1, the capacitance of the negative electrode of the load / PCS device relative to the reference ground is a second capacitance 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; The controller BMS_MCU receives data from the battery pack positive pole analog quantity acquisition interface ADx and the battery pack negative pole analog quantity acquisition interface ADy, and 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; the controller BMS_MCU receives communication data and working feedback signals of the load / PCS device.

2. The battery management system insulation leakage detection device according to claim 1, characterized in that: The controller BMS_MCU is connected to the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy through a control line.

3. The battery management system insulation leakage detection device according to claim 1, characterized in that: The controller BMS_MCU is connected to the load / PCS device via a communication line to receive communication data of the load / PCS device; the controller BMS_MCU is connected to the load / PCS device via a signal feedback line to obtain a feedback signal of the load / PCS device.

4. The battery management system insulation leakage detection device according to claim 1, 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 power on and off of the coils of the corresponding contactors or relays.

5. A detection method for the insulation leakage detection device of a battery management system according to any one of claims 1 to 4, characterized in that: 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 capacitance C1, and the capacitance of the negative electrode of the load / PCS device relative to the reference ground is a second capacitance C2, comprising the following steps: Determine whether the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage division value of the positive analog quantity acquisition interface ADx of the battery pack and the negative analog quantity acquisition interface ADy of the battery pack, and if so, control the fourth switch SW4 and the fifth switch SW5 to be disconnected at the same time; if not, control the fourth switch SW4 and the fifth switch SW5 to be closed at the same time; Control the first switch SW1 and the second switch SW2 to be closed, and the third switch SW3 to be open; obtain the voltage division values ​​of the positive analog quantity acquisition interface ADx and the negative analog quantity acquisition interface ADy of the battery pack at this time, which are the positive first voltage division value Up1 and the negative first voltage division value Un1 respectively; Control the first switch SW1 to be closed, and the second switch SW2 and the third switch SW3 to be open; obtain the voltage division values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy at this time, which are the positive electrode second voltage division value Up2 and the negative electrode second voltage division value Un2 respectively; Control the first switch SW1 to be turned off, the second switch SW2 to be turned on, and the third switch SW3 to be turned off, and obtain the voltage division values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy at this time, which are the positive electrode third voltage division value Up3 and the negative electrode third voltage division value Un3 respectively; Control the first switch SW1, the second switch SW2 and the third switch SW3 to close, and obtain the voltage division values ​​of the battery pack positive electrode analog quantity acquisition interface ADx and the battery pack negative electrode analog quantity acquisition interface ADy at this time, which are the positive electrode fourth voltage division value Up4 and the negative electrode fourth voltage division value Un4 respectively; The first leakage resistance Rx and the second leakage resistance Ry are calculated.

6. The detection method of the insulation leakage detection device of the battery management system according to claim 5, characterized in that: 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 satisfy the following relationship: R1=R4 R2=R3 R5=R6=R7 When the fourth switch SW4 and the fifth switch SW5 are closed at the same time, the first leakage resistance Rx and the second leakage resistance Ry are calculated by the following formula: Among them, Up1 is the first voltage division value of the positive electrode, and Un1 is the first voltage division value of the negative electrode; Up2 is the second voltage division value of the positive electrode, and Un2 is the second voltage division value of the negative electrode; Up3 is the third voltage division value of the positive electrode, and Un3 is the third voltage division value of the negative electrode; 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.

7. The detection method of the insulation leakage detection device of the battery management system according to claim 5, characterized in that: 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 satisfy the following relationship: R1=R4 R2=R3 R5=R6=R7 When the fourth switch SW4 and the fifth switch SW5 are turned off at the same time, the first leakage resistance Rx and the second leakage resistance Ry can be calculated by the following formula: E=((R5×(R3+R4)) / (R3+R4+R5)) Among them, 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.

8. The detection method of the insulation leakage detection device of the battery management system according to claim 5, characterized in that: Determine the influence of the first capacitor C1 and the second capacitor C2 on the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy, including: switching the state of the first switch SW1, the second switch SW2 or the third switch SW3, and checking the change of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy during the state switching process. If the voltage divider value changes, it means that the first capacitor C1 and the second capacitor C2 do not affect the measurement of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy; if the voltage divider value remains unchanged, it means that the first capacitor C1 and the second capacitor C2 affect the measurement of the voltage divider value of the battery pack positive analog quantity acquisition interface ADx and the battery pack negative analog quantity acquisition interface ADy.

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