Insulation resistance detection circuit and insulation resistance detection device of battery module

Abstract

The embodiment of the invention discloses an insulation resistance detection circuit and an insulation resistance detection device of a battery module, and belongs to the technical field of resistance detection. Wherein the insulation resistance detection circuit comprises a detection port for detecting to-be-detected insulation resistance of the port to the ground, and the detection port of the insulation resistance detection circuit is connected to the positive electrode of any cell in the battery module; the processor is respectively connected with the first switch, the second switch and the voltage sampling unit, and is used for determining an impedance value of the to-be-detected insulation impedance and a voltage value of the detection port based on the voltage sampled by the voltage sampling unit in a process of controlling the connection or disconnection of the first switch and the second switch; when the insulation impedance of any cell is determined to be abnormal based on the impedance value of the to-be-detected insulation impedance, the number of cells to which any cell belongs in the battery module is determined based on the voltage value of the detection port, and the cells with abnormal insulation impedance in the battery module can be accurately determined.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of impedance detection, and in particular to an insulation impedance detection circuit and an insulation impedance detection device for a battery module. Background Art

[0002] A battery cell is the most basic component of a battery, usually an electrochemical device encapsulated in a metal shell. It is a unit that stores and releases electrical energy, converting chemical energy into electrical energy through chemical reactions. A battery cell is usually composed of a positive electrode, a negative electrode, a separator, and an electrolyte. Common types of batteries include lithium batteries, nickel-metal hydride batteries, lead-acid batteries, etc. When a battery cell is used in lithium batteries, nickel-metal hydride batteries, lead-acid batteries, etc., multiple battery cells are usually assembled in series into a battery module (Battery Module), which provides higher voltage and capacity.

[0003] In order to ensure that the battery module is normal, it is necessary to perform insulation impedance testing on the battery module. In the existing battery module insulation impedance testing, the insulation impedance of the entire battery module is generally tested to determine whether the insulation impedance of the battery module is abnormal. However, the battery module contains multiple cells, and it is difficult to determine the cell with abnormal insulation impedance in the battery module by testing the insulation impedance of the entire battery module. Summary of the invention

[0004] The embodiments of the present application provide an insulation impedance detection circuit and an insulation impedance detection device for a battery module, which can accurately determine the battery cells with abnormal insulation impedance in the battery module.

[0005] The embodiment of the present application provides an insulation impedance detection circuit of a battery module, the battery module includes a plurality of battery cells connected in series, the insulation impedance detection circuit includes: a detection port, an insulation impedance to be measured of the detection port to ground, a first switch, a second switch, a first resistor, a second resistor, a third resistor, a fourth resistor, a voltage sampling unit, and a processor;

[0006] One end of the first resistor and one end of the second resistor are connected to the positive electrode of the battery module, and the other end of the first resistor is connected to a node between the insulation impedance to be measured and the ground terminal via the first switch;

[0007] The other end of the second resistor is connected to one end of the fourth resistor via the node, and the other end of the fourth resistor is connected to the negative electrode of the battery module; the sampling end of the voltage sampling unit is connected to both ends of the fourth resistor or the second resistor;

[0008] One end of the third resistor is connected to the node via the second switch, and the other end of the third resistor is connected to the negative electrode of the battery module;

[0009] The detection port of the insulation impedance detection circuit is connected to the positive electrode of any battery cell in the battery module;

[0010] The processor is respectively connected to the first switch, the second switch and the voltage sampling unit, and is used to determine the impedance value of the insulation impedance to be measured and the voltage value of the detection port based on the voltage sampled by the voltage sampling unit during the process of controlling the first switch and the second switch to be closed or opened; when it is determined that the insulation impedance of any battery cell is abnormal based on the impedance value of the insulation impedance to be measured, the number of cells to which any battery cell belongs in the battery module is determined based on the voltage value of the detection port.

[0011] Furthermore, it also includes: a third switch;

[0012] A connection point between the other end of the second resistor and one end of the fourth resistor is connected to the node via the third switch;

[0013] The processor is connected to the third switch, and is used to control the third switch to be closed during the process of controlling the closing or opening of the first switch and the second switch, and to control the third switch to be opened after the voltage sampling unit samples the voltage.

[0014] Furthermore, the detection port of the insulation impedance detection circuit is detachably connected to the positive electrode of each battery cell in the battery module one by one;

[0015] The processor is used to determine whether the insulation impedance of the battery cell is abnormal section by section.

[0016] Furthermore, the processor is specifically used to control the first switch to be closed and the second switch to be opened, and obtain the first voltage sampled by the voltage sampling unit;

[0017] Controlling the first switch to be disconnected and controlling the second switch to be closed to obtain a second voltage sampled by the voltage sampling unit;

[0018] Based on the first voltage and the second voltage, an impedance value of the insulation impedance to be measured and a voltage value of the detection port are determined.

[0019] Further, the processor is specifically configured to control the first switch to be disconnected and the second switch to be disconnected, and obtain a third voltage sampled by the voltage sampling unit;

[0020] Controlling any one of the first switch and the second switch to be closed and the other switch to be opened, and obtaining a fourth voltage sampled by the voltage sampling unit;

[0021] Based on the third voltage and the fourth voltage, an impedance value of the insulation impedance to be measured and a voltage value of the detection port are determined.

[0022] Further, the first switch includes: a first relay, and the second switch includes: a second relay;

[0023] The other end of the first resistor is connected to a node between the insulation impedance to be measured and the ground terminal via a normally open contact of the first relay;

[0024] One end of the third resistor is connected to the node via the normally open contact of the second relay;

[0025] The processor is connected to the coil of the first relay and the coil of the second relay.

[0026] Furthermore, the processor is specifically configured to determine that the insulation impedance of any of the battery cells is abnormal if the impedance value of the insulation impedance to be measured is less than a preset impedance threshold;

[0027] If the impedance value of the insulation impedance to be measured is greater than or equal to the preset impedance threshold, it is determined that the insulation impedance of any battery cell is normal.

[0028] Furthermore, the processor is specifically used to obtain the voltage value of a single battery cell in the battery module, divide the voltage value of the detection port by the voltage value of the single battery cell to obtain a target quotient value, and determine the number of cells to which any one battery cell belongs in the battery module based on the target quotient value.

[0029] Furthermore, the voltage sampling unit includes: an impedance matching module, an operational amplifier and a voltage dividing and filtering module;

[0030] The input end of the impedance matching module is connected to the two ends of the fourth resistor or the second resistor, and the output end of the impedance matching module is respectively connected to the in-phase input end and the inverting input end of the operational amplifier, and the impedance matching module is used to perform impedance matching on the differential voltage signal at the two ends of the resistor and then input it into the operational amplifier;

[0031] The output end of the operational amplifier is connected to the input end of the voltage divider filter module, and the operational amplifier is used to perform operational amplifier following on the differential voltage signal and output a corresponding single-ended voltage signal;

[0032] The voltage division and filtering module is used to perform voltage division and filtering on the single-ended voltage signal and output the voltage obtained by sampling.

[0033] The embodiment of the present application further provides an insulation impedance detection device for a battery module, which uses the above-mentioned insulation impedance detection circuit to perform insulation impedance detection on the battery module.

[0034] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0035] By connecting the detection port of the insulation impedance detection circuit to the positive electrode of any battery cell in the battery module, the processor determines the impedance value of the insulation impedance to be measured and the voltage value of the detection port based on the voltage sampled by the voltage sampling unit during the process of controlling the closing or opening of the first switch and the second switch, which are the impedance value of the insulation impedance of any battery cell and the corresponding voltage value of any battery cell in the battery module; when the insulation impedance of any battery cell is abnormal, the number of cells to which any battery cell belongs in the battery module is determined based on the voltage value of the detection port, so that the battery cells with abnormal insulation impedance in the battery module can be accurately determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0037] Figure 1 An insulation impedance detection circuit diagram of a battery module disclosed in an embodiment of the present application;

[0038] Figure 2 It is an insulation impedance detection circuit diagram of another battery module disclosed in an embodiment of the present application;

[0039] Figure 3 A circuit diagram of a voltage sampling unit disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] In the description of the embodiments of the present application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present application.

[0042] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0043] In the existing battery module insulation impedance detection, the insulation impedance of the entire battery module is generally detected, that is, the insulation impedance of the positive electrode of the battery module to the ground is detected to determine whether the insulation impedance of the battery module is abnormal. However, the battery module contains multiple cells, and it is difficult to determine the cells with abnormal insulation impedance in the battery module by detecting the insulation impedance of the entire battery module. Therefore, the embodiment of the present application provides an insulation impedance detection circuit for a battery module, which can accurately determine the cells with abnormal insulation impedance in the battery module. The insulation impedance detection circuit is as follows Figure 1 As shown, the details are as follows:

[0044] In the embodiment of the present application, the battery module (which may be called a battery pole) includes a plurality of battery cells connected in series. In the figure, BAT+ represents the positive electrode of the battery module, and 0V represents the negative electrode of the battery module (that is, the reference ground). The battery module may include 18 3.3V battery cells connected in series or 16 3.3V battery cells connected in series, which is not limited here.

[0045] The insulation impedance detection circuit includes: a detection port, an insulation impedance Rx to be measured between the detection port and the ground, a first switch K1, a second switch K2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a voltage sampling unit and a processor (not shown). Among them, one end of the first resistor R1 and one end of the second resistor R2 are connected to the positive electrode BAT+ of the battery module, and the other end of the first resistor R1 is connected to the node between the insulation impedance Rx to be measured and the ground terminal through the first switch K1; that is, the first resistor R1 is connected to the node through the attraction of the first switch K1. Among them, the ground terminal can be a signal ground, a chassis ground or a protective ground, etc., which is not limited here.

[0046] The other end of the second resistor R2 is connected to one end of the fourth resistor R4 via a node, and the other end of the fourth resistor R4 is connected to the negative electrode 0V of the battery module. The sampling end of the voltage sampling unit is connected to both ends of the fourth resistor R4 or the second resistor R2; it can be understood that when the sampling end of the voltage sampling unit is connected to both ends of the fourth resistor R4, the voltage sampling unit samples the voltage across the fourth resistor R4; when the sampling end of the voltage sampling unit is connected to both ends of the second resistor R2, the voltage sampling unit samples the voltage across the second resistor R2. In the embodiment of the present application, the insulation impedance detection circuit will be described by taking the voltage sampling unit sampling the voltage across the fourth resistor R4 as an example. In the insulation impedance detection circuit, the voltage sampling unit can also sample the voltage across the second resistor R2, which will not be repeated below.

[0047] Among them, one end of the third resistor R3 is connected to the node through the second switch K2, and the other end of the third resistor R3 is connected to the module negative electrode 0V of the battery module. The detection port of the insulation impedance detection circuit is connected to the positive electrode of any battery cell in the battery module; it can be understood that the insulation impedance Rx to be measured of the detection port to the ground is the insulation impedance of any battery cell to the ground, and the voltage Vx of the detection port is the voltage of any battery cell to the ground.

[0048] The processor is connected to the first switch K1, the second switch K2 and the voltage sampling unit respectively, and is used to determine the impedance value of the insulation resistance Rx to be measured and the voltage value of the voltage Vx on the detection port based on the voltage sampled by the voltage sampling unit during the process of controlling the first switch K1 and the second switch K2 to be closed or disconnected; specifically, based on the principle that the node current of the node is 0A, that is, the principle that the input current of the node is equal to the output current, by controlling the first switch K1 and the second switch K2 to be closed or disconnected, based on the voltage sampled by the voltage sampling unit, multiple node current equations including the impedance value of the insulation resistance to be measured and the voltage value of the detection port are established to obtain the impedance value of the insulation resistance to be measured and the voltage value of the detection port. The processor can be a microcontroller (MCU) or a digital signal processor (DSP), which is not specifically limited here.

[0049] After obtaining the impedance value of the insulation impedance to be measured and the voltage value of the detection port, the processor can determine whether the insulation impedance of any battery cell is abnormal based on the impedance value of the insulation impedance to be measured; specifically, in order for the battery cell to be effectively insulated from the ground, the insulation impedance of the battery cell generally needs to be greater than a preset impedance threshold; the preset impedance threshold can be 10Ω or 20Ω, which is not specifically limited here. If the impedance value of the insulation impedance to be measured is less than the preset impedance threshold, it is determined that the insulation impedance of any battery cell is abnormal; if the impedance value of the insulation impedance to be measured is greater than or equal to the preset impedance threshold, it is determined that the insulation impedance of any battery cell is normal.

[0050] When the insulation impedance of any battery cell is determined to be abnormal based on the impedance value of the insulation impedance to be measured, the number of cells to which any battery cell belongs in the battery module is determined based on the voltage value of the detection port, that is, when it is determined that any battery cell is a battery cell with abnormal insulation impedance, the position of the battery with abnormal insulation impedance in the battery module can be determined. Specifically, the processor can obtain the voltage value of a single battery cell in the battery module. It can be understood that the voltage value of each battery cell in the battery module is the same, and the voltage value of a single battery cell can be 3.3V or 4.5V, which is not specifically limited here. The voltage value of the detection port is divided by the voltage value of the single battery cell to obtain a target quotient value, and the number of cells to which any battery cell belongs in the battery module is determined based on the target quotient value. The voltage value of the detection port divided by the voltage value of a single battery cell is obtained by adding up to 1 to get the number of cells in the battery module where the insulation impedance is abnormal. For example, if the voltage value of a single battery cell is 3.3V and the voltage value of the detection port is 6.5V, the target quotient value is approximately 1.97. It can be obtained that the cell belongs to the second cell in the battery module, and the detection port is connected to the positive electrode of the second cell (or the negative electrode of the third cell).

[0051] It can be seen that in the embodiment of the present application, by connecting the detection port of the insulation impedance detection circuit to the positive electrode of any battery cell in the battery module, the processor, in the process of controlling the closing or opening of the first switch and the second switch, determines the impedance value of the insulation impedance to be measured and the voltage value of the detection port based on the voltage sampled by the voltage sampling unit, which are the impedance value of the insulation impedance of any battery cell and the corresponding voltage value of any battery cell in the battery module; when the insulation impedance of any battery cell is abnormal, the number of cells to which any battery cell belongs in the battery module is determined based on the voltage value of the detection port, so that the battery cells with abnormal insulation impedance in the battery module can be accurately determined.

[0052] Further, such as Figure 2As shown, in the embodiment of the present application, the insulation impedance detection circuit also includes: a third switch K3, one end of the second resistor R2 is connected to the module positive electrode BAT+ of the battery module, and the other end of the second resistor R2 is connected in series with one end of the fourth resistor R4; the connection point between the other end of the second resistor R2 and one end of the fourth resistor R4 is connected to the node through the third switch K3; the processor is connected to the third switch K3, and is used to control the third switch K3 to be attracted in the process of controlling the attraction or disconnection of the first switch K1 and the second switch K2, and control the third switch K3 to be disconnected after the voltage sampling unit samples the voltage. That is, the processor controls the third switch K3 to be attracted during the detection process of the insulation impedance detection circuit, and incorporates the second resistor R2 and the fourth resistor R4 into the node between the insulation impedance to be measured and the ground terminal, so as to associate the voltage sampled by the voltage sampling unit with the impedance value of the insulation impedance to be measured and the voltage value of the detection port, and obtain the corresponding node current equation; after the detection is completed, the third switch K3 is controlled to be disconnected, which can effectively prevent the current of the second resistor R2 from flowing back to the battery module through the node and the detection port, thereby improving the safety of the battery module.

[0053] Furthermore, in an embodiment of the present application, the detection port of the insulation impedance detection circuit can be detachably connected to the positive pole of each battery cell in the battery module one by one; for example, the detection port can be connected from the positive pole of the first battery cell to the positive pole of the last battery cell; the processor is used to determine the impedance value of the corresponding insulation impedance to be measured when the detection port is connected to the positive pole of the battery cell, and determine whether the insulation impedance of the battery cell is abnormal based on the impedance value of the insulation impedance to be measured; the insulation impedance of each battery cell in the battery module can be comprehensively detected, thereby improving the accuracy of insulation impedance detection in the battery module.

[0054] Furthermore, the detection function principle of the insulation impedance detection circuit is as follows: the processor is specifically used to control the first switch K1 to be closed and the second switch K2 to be disconnected, and obtain the first voltage V1 sampled by the voltage sampling unit, that is, the voltage across the fourth resistor R4; based on the principle that the node current is 0, the node current equation that can be obtained at this time is:

[0055] Where V BAT is the voltage of the battery module, Vx is the voltage of the detection port, and Rx is the insulation resistance to be measured.

[0056] The first switch K1 is controlled to be disconnected and the second switch K2 is controlled to be closed, and the second voltage V2 sampled by the voltage sampling unit is obtained; based on the principle that the node current is 0, the node current equation that can be obtained at this time is:

[0057]

[0058] Based on the first voltage and the second voltage, an impedance value of the insulation impedance to be measured and a voltage value of the detection port are determined.

[0059] That is, based on formula 1 and formula 2, we can get:

[0060]

[0061] Further, in the embodiment of the present application, the detection principle of the insulation impedance detection circuit can also be: the processor is specifically used to control the first switch K1 to be disconnected and the second switch K2 to be disconnected, and obtain the third voltage V3 sampled by the voltage sampling unit; at this time, the node current equation obtained is:

[0062]

[0063] Control any one of the first switch K1 and the second switch K2 to be closed and the other switch to be disconnected, and obtain the fourth voltage V4 sampled by the voltage sampling unit; when the first switch K1 is controlled to be closed and the second switch K2 is disconnected, the obtained node current equation is the above-mentioned formula 1, and when the first switch K1 is controlled to be disconnected and the second switch K2 is controlled to be closed, the obtained node current equation is the above-mentioned formula 2; based on the third voltage and the fourth voltage, determine the impedance value of the insulation impedance to be measured and the voltage value of the detection port.

[0064] It is understandable that the first switch K1 and the second switch K2 may be controlled to be closed and opened in a variety of control modes, thereby obtaining the impedance value of the insulation impedance to be measured and the voltage value of the detection port based on the voltage sampled by the voltage sampling unit.

[0065] Further, the first switch K1 includes: a first relay, and the second switch K2 includes: a second relay; the other end of the first resistor R1 is connected to the node between the insulation impedance to be measured and the ground terminal via the normally open contact of the first relay; one end of the third resistor R3 is connected to the node via the normally open contact of the second relay; the processor is connected to the coil of the first relay and the coil of the second relay. When the processor does not supply power to the coil of the relay, the normally open contact of the relay remains disconnected, and when the processor supplies power to the coil of the relay, the normally open contact of the relay is closed, realizing the switching function of the relay.

[0066] Further, in the embodiment of the present application, the voltage sampling unit includes: an impedance matching module 301, an operational amplifier IC and a voltage divider filter module 302; wherein VPE+ is the voltage at the positive end of the resistor, VPE- is the voltage at the negative end of the resistor, and VPE+ and VPE- form a differential voltage signal; the input end of the impedance matching module 301 is the sampling end of the voltage sampling unit, the input end of the impedance matching module 301 is connected to the two ends of the fourth resistor or the second resistor, and the output end of the impedance matching module 301 is respectively connected to the in-phase input end and the inverting input end of the operational amplifier IC; wherein the impedance matching module 301 includes: resistors R5 and R6, Diodes D1, D2, D3 and D4, capacitors C1 and C2; the impedance matching module 301 is used to perform impedance matching on the differential voltage signal at both ends of the resistor and then input it into the operational amplifier IC; the output end of the operational amplifier IC is connected to the input end of the voltage divider filter module 302, the operational amplifier IC is used to perform op amp follow on the differential voltage signal and output the corresponding single-ended voltage signal; the voltage divider filter module 302 includes: resistors R7 and R8, diodes D5 and D6, capacitor C3, the voltage divider filter module 302 is used to perform voltage divider filtering on the single-ended voltage signal and output the sampled voltage AD_VPE (AD sampling voltage).

[0067] In an practicable manner, the insulation impedance detection circuit can be verified based on the impedance value of the insulation impedance to be measured and the voltage value of the detection port detected by the insulation impedance detection circuit; specifically, impedances of different resistance values ​​can be connected in series between the positive electrode and the ground terminal of different battery cells to test the actual battery cell voltage and the actual insulation impedance with the insulation impedance to be measured and the voltage of the detection port detected by the processor; wherein, the detection range of the insulation impedance is generally 0 to 198 kΩ, and the impedances of different resistance values ​​can be 0.000 kΩ resistor, 0.010 kΩ resistor, 0.0468 kΩ resistor, 0.910 kΩ resistor, 20.45 kΩ resistor, 49.50 kΩ resistor or 198 kΩ resistor; if a 0.000 kΩ resistor is connected in series between the positive electrode and the ground terminal of different battery cells, the corresponding data can be obtained as shown in the following table:

[0068]

[0069] Among them, the theoretical Rx is the actual resistance between the positive pole and the ground terminal of different cells connected in series, the theoretical Vx is the actual voltage on the cell, the displayed Rx is the insulation impedance detected by the insulation impedance detection circuit, and the displayed Vx is the voltage of the detection port detected by the insulation impedance detection circuit; the sampling accuracy is the displayed value divided by the theoretical value. It can be seen that the sampling accuracy of the insulation impedance of 1 to 198 kΩ is ≥96%; the corresponding sampling accuracy of the cell voltage is ≥95%, and the sampling accuracy of the insulation impedance and the cell voltage meets the requirements.

[0070] Similarly, the maximum deviation between the displayed Rx and the theoretical Rx, as well as the maximum value of the insulation resistance within the measurement range can be obtained; the sampling linearity of the insulation resistance can be obtained = 1-maximum deviation value divided by the maximum value, and the obtained sampling linearity of the insulation resistance is ≥97%; correspondingly, the obtained sampling linearity of the cell voltage is ≥97%, and the sampling linearity of the insulation resistance and the cell voltage both meet the requirements.

[0071] Since the battery module may be used in high and low temperature environments, such as S 3 The overall application temperature environment of the lithium battery is 0-40℃. At this time, the insulation impedance detection circuit can be placed in a high and low temperature environment, and the insulation impedance detection circuit can be calibrated. The method of checking the sampling accuracy and sampling linearity is similar to the above. It can be obtained that in high and low temperature environments, the sampling accuracy of the insulation impedance and the battery cell voltage meets the requirements, and the sampling linearity of the insulation impedance and the battery cell voltage meets the requirements.

[0072] The embodiment of the present application further provides an insulation impedance detection device for a battery module, characterized in that the insulation impedance detection circuit mentioned above is used to perform insulation impedance detection on the battery module.

[0073] In the present invention, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "plurality" refers to two or more, unless otherwise clearly defined.

[0074] The above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, rather than to limit them. Although the embodiments of the present application are described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and description of the embodiments of the present application.

Claims

1. An insulation impedance detection circuit for a battery module, the battery module comprising a plurality of battery cells connected in series, characterized in that: The insulation impedance detection circuit comprises: a detection port, an insulation impedance to be measured between the detection port and ground, a first switch, a second switch, a first resistor, a second resistor, a third resistor, a fourth resistor, a voltage sampling unit and a processor; One end of the first resistor and one end of the second resistor are connected to the positive electrode of the battery module, and the other end of the first resistor is connected to a node between the insulation impedance to be measured and the ground terminal via the first switch; The other end of the second resistor is connected to one end of the fourth resistor via the node, and the other end of the fourth resistor is connected to the negative electrode of the battery module; the sampling end of the voltage sampling unit is connected to both ends of the fourth resistor or the second resistor; One end of the third resistor is connected to the node via the second switch, and the other end of the third resistor is connected to the negative electrode of the battery module; The detection port of the insulation impedance detection circuit is connected to the positive electrode of any battery cell in the battery module; The processor is respectively connected to the first switch, the second switch and the voltage sampling unit, and is used to determine the impedance value of the insulation impedance to be measured and the voltage value of the detection port based on the voltage sampled by the voltage sampling unit during the process of controlling the first switch and the second switch to be closed or opened; when it is determined that the insulation impedance of any battery cell is abnormal based on the impedance value of the insulation impedance to be measured, the number of cells to which any battery cell belongs in the battery module is determined based on the voltage value of the detection port.

2. The insulation impedance detection circuit according to claim 1, characterized in that: Also includes: The third switch; A connection point between the other end of the second resistor and one end of the fourth resistor is connected to the node via the third switch; The processor is connected to the third switch, and is used to control the third switch to be closed during the process of controlling the closing or opening of the first switch and the second switch, and to control the third switch to be opened after the voltage sampling unit samples the voltage.

3. The insulation impedance detection circuit according to claim 1, characterized in that: The detection port of the insulation impedance detection circuit is detachably connected to the positive electrode of each battery cell in the battery module one by one; The processor is used to determine whether the insulation impedance of the battery cell is abnormal section by section.

4. The insulation impedance detection circuit according to claim 1, characterized in that: The processor is specifically configured to control the first switch to be closed and the second switch to be opened, and obtain the first voltage sampled by the voltage sampling unit; Controlling the first switch to be disconnected and controlling the second switch to be closed to obtain a second voltage sampled by the voltage sampling unit; Based on the first voltage and the second voltage, an impedance value of the insulation impedance to be measured and a voltage value of the detection port are determined.

5. The insulation impedance detection circuit according to claim 1, characterized in that: The processor is specifically configured to control the first switch to be disconnected and the second switch to be disconnected, and obtain a third voltage sampled by the voltage sampling unit; Controlling any one of the first switch and the second switch to be closed and the other switch to be opened, and obtaining a fourth voltage sampled by the voltage sampling unit; Based on the third voltage and the fourth voltage, an impedance value of the insulation impedance to be measured and a voltage value of the detection port are determined.

6. The insulation impedance detection circuit according to claim 1, characterized in that: The first switch includes: a first relay, and the second switch includes: a second relay; The other end of the first resistor is connected to a node between the insulation impedance to be measured and the ground terminal via a normally open contact of the first relay; One end of the third resistor is connected to the node via the normally open contact of the second relay; The processor is connected to the coil of the first relay and the coil of the second relay.

7. The insulation impedance detection circuit according to claim 1, characterized in that: The processor is specifically configured to determine that the insulation impedance of any battery cell is abnormal if the impedance value of the insulation impedance to be measured is less than a preset impedance threshold; If the impedance value of the insulation impedance to be measured is greater than or equal to the preset impedance threshold, it is determined that the insulation impedance of any battery cell is normal.

8. The insulation impedance detection circuit according to claim 1, characterized in that: The processor is specifically used to obtain the voltage value of a single battery cell in the battery module, divide the voltage value of the detection port by the voltage value of the single battery cell to obtain a target quotient value, and determine the number of cells to which any one battery cell belongs in the battery module based on the target quotient value.

9. The insulation impedance detection circuit according to claim 1, characterized in that: The voltage sampling unit includes: an impedance matching module, an operational amplifier and a voltage dividing and filtering module; The input end of the impedance matching module is connected to the two ends of the fourth resistor or the second resistor, and the output end of the impedance matching module is respectively connected to the in-phase input end and the inverting input end of the operational amplifier, and the impedance matching module is used to perform impedance matching on the differential voltage signal at the two ends of the resistor and then input it into the operational amplifier; The output end of the operational amplifier is connected to the input end of the voltage divider filter module, and the operational amplifier is used to perform operational amplifier following on the differential voltage signal and output a corresponding single-ended voltage signal; The voltage division and filtering module is used to perform voltage division and filtering on the single-ended voltage signal and output the voltage obtained by sampling.

10. An insulation impedance detection device for a battery module, characterized in that: The insulation impedance detection circuit according to any one of claims 1 to 9 is used to perform insulation impedance detection on the battery module.

Images