Insulation detection circuit and method, and battery management system

Abstract

An insulation detection circuit and method, and a battery management system. In the insulation detection circuit, a first switch is provided in a first voltage divider circuit, a second switch is provided in a second voltage divider circuit, a third switch is provided in a fourth voltage divider circuit, the first voltage divider circuit is connected in series between a positive terminal and a first reference node, the fourth voltage divider circuit is connected in series between the positive terminal and a second reference node, the second voltage divider circuit is connected in series between the second reference node and the first reference node, and the third voltage divider circuit is connected in series between a negative terminal and the first reference node. On the basis of the on / off-states of the first switch, the second switch and the third switch combined with the voltages collected by the first voltage divider circuit, the second voltage divider circuit and the third voltage divider circuit, the resistance value of a first equivalent insulation resistor and the resistance value of a second equivalent insulation resistor are determined in order to determine whether the state of insulation between the positive terminal and the second reference node and the state of insulation between the negative terminal and the second reference node are abnormal.

Description

Insulation detection circuit, method, and battery management system

[0001] Cross-reference to related applications

[0002] The present disclosure is based on and claims priority to Chinese Patent Application No. 202410866351.4, filed on June 28, 2024, entitled “Insulation detection circuit, method, and battery management system,” the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of batteries, and in particular to an insulation detection circuit, method, and battery management system. BACKGROUND

[0004] A power battery is one of the core components of an electric vehicle. Since the power battery has a direct current high-voltage output, if the positive and negative insulation of the high-voltage loop is damaged and the vehicle ground (low-voltage power supply ground) is virtually connected, it may cause the risk of electric shock and high-voltage short circuit for passengers. Therefore, insulation detection is an important part of the safety consideration for the use of the power battery.

[0005] In related technologies, although some insulation detection circuits already exist, the existing insulation detection circuits all have some defects, such as high cost, complex circuit structure, and inability to meet the demand for multiple voltage sampling channels. SUMMARY

[0006] The present disclosure provides an insulation detection circuit, method, and battery management system, which can simplify the circuit structure, reduce the cost, and also solve the problem of inconvenient expansion of voltage sampling channels.

[0007] The technical solution of the present disclosure is implemented as follows:

[0008] In a first aspect, the present disclosure provides an insulation detection circuit, which comprises a first voltage dividing circuit, a second voltage dividing circuit, a third voltage dividing circuit, and a fourth voltage dividing circuit, wherein:

[0009] The first voltage dividing circuit is provided with a first switch, the second voltage dividing circuit is provided with a second switch, and the fourth voltage dividing circuit is provided with a third switch. The first voltage dividing circuit is connected in series between the positive terminal and a first reference node, the fourth voltage dividing circuit is connected in series between the positive terminal and a second reference node, the second voltage dividing circuit is connected in series between the second reference node and the first reference node, and the third voltage dividing circuit is connected in series between the negative terminal and the first reference node.

[0010] The insulation detection circuit is used for determining the resistance values of the first equivalent insulation resistance and the second equivalent insulation resistance based on the opening and closing states of the first switch, the second switch and the third switch, and the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit; and determining whether the insulation states between the positive terminal and the second reference node and between the negative terminal and the second reference node are abnormal according to the resistance values of the first equivalent insulation resistance and the second equivalent insulation resistance.

[0011] The first equivalent insulation resistance represents an equivalent resistance value between the positive terminal and the second reference node, and the second equivalent insulation resistance represents an equivalent resistance value between the negative terminal and the second reference node.

[0012] By the above technical means, the insulation detection circuit can not only use the first voltage dividing circuit and the third voltage dividing circuit for voltage sampling, but also use the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit and the fourth voltage dividing circuit for insulation detection, so that voltage sampling and insulation detection can be realized at the same time, the circuit structure of the circuit capable of realizing multiple functions is simplified, and the cost is reduced; and the first calculation voltage and the second calculation voltage and the third calculation voltage and the fourth calculation voltage obtained according to the opening and closing states of the first switch, the second switch and the third switch can also be used for calculating the resistance value of the equivalent insulation resistance; in addition, when the first voltage dividing circuit and the third voltage dividing circuit are used to form a voltage sampling channel, the elements in the first voltage dividing circuit and the third voltage dividing circuit do not participate in the calculation of the equivalent insulation resistance, and the parallel connection of multiple first voltage dividing circuits does not change the resistance value of the equivalent insulation resistance, and multiple first voltage dividing circuits can be connected in parallel here, so that the multiple first voltage dividing circuits and the third voltage dividing circuit can form many voltage sampling channels, thereby solving the problem of inconvenient expansion of the voltage sampling channel in the related art, and improving the expansion flexibility of the voltage sampling channel.

[0013] In some embodiments, the insulation detection circuit is configured to, when the first switch is closed and the second switch and the third switch are open, acquire a first sampling voltage through the first voltage dividing circuit, acquire a second sampling voltage through the second voltage dividing circuit, acquire a third sampling voltage through the third voltage dividing circuit, and determine a first calculation voltage across the first equivalent insulation resistor and a second calculation voltage across the second equivalent insulation resistor according to the first sampling voltage, the second sampling voltage and the third sampling voltage; and is further configured to, according to the first calculation voltage and the second calculation voltage, determine the opening and closing states of the second switch and the third switch, acquire a fourth sampling voltage through the first voltage dividing circuit, acquire a fifth sampling voltage through the second voltage dividing circuit, acquire a sixth sampling voltage through the third voltage dividing circuit, and determine a third calculation voltage across the first equivalent insulation resistor and a fourth calculation voltage across the second equivalent insulation resistor according to the fourth sampling voltage, the fifth sampling voltage and the sixth sampling voltage; and is further configured to, according to the first calculation voltage and the third calculation voltage across the first equivalent insulation resistor and the second calculation voltage and the fourth calculation voltage across the second equivalent insulation resistor, determine the resistance values of the first equivalent insulation resistor and the second equivalent insulation resistor.

[0014] Through the above technical means, when the first switch is closed and the second switch and the third switch are open, the first calculation voltage across the first equivalent insulation resistor and the second calculation voltage across the second equivalent insulation resistor can be determined according to the acquired first sampling voltage, the second sampling voltage and the third sampling voltage; when the second switch or the third switch is closed, the third calculation voltage across the first equivalent insulation resistor and the fourth calculation voltage across the second equivalent insulation resistor can be determined according to the acquired fourth sampling voltage, the fifth sampling voltage and the sixth sampling voltage, and the resistance values of the first equivalent insulation resistor Rp and the second equivalent insulation resistor Rn are further calculated, so that the calculation of the equivalent insulation resistance can be realized, and whether the insulation states between the positive terminal and the second reference node and between the negative terminal and the second reference node are abnormal can be determined.

[0015] In some embodiments, the insulation detection circuit is further configured to, when the first calculation voltage is greater than or equal to the second calculation voltage, determine that the second switch is closed and the third switch is open; or, when the first calculation voltage is less than the second calculation voltage, determine that the third switch is closed and the second switch is open.

[0016] Through the above technical means, the sizes of the first calculation voltage and the second calculation voltage are compared to determine which of the second switch and the third switch is closed, so that the third calculation voltage across the first equivalent insulation resistor and the fourth calculation voltage across the second equivalent insulation resistor can be obtained more accurately, and the accuracy of calculating the equivalent insulation resistance is improved.

[0017] In some embodiments, the first voltage dividing circuit includes a first voltage dividing unit and a first switch, and the third voltage dividing circuit includes a second voltage dividing unit and a first detection unit; a first end of the first switch is connected with the positive terminal, a second end of the first switch is connected with a first end of the first voltage dividing unit, a second end of the first voltage dividing unit is connected with the first reference node and a first end of the second voltage dividing unit respectively, a first sampling node is arranged in the first voltage dividing unit and used to obtain a first collected voltage or a fourth collected voltage; a second end of the second voltage dividing unit is connected with the negative terminal, a third end of the second voltage dividing unit is connected with the first detection unit, and a third sampling node is arranged in the first detection unit and used to obtain a third collected voltage or a sixth collected voltage.

[0018] According to the above technical means, the first sampling node in the first voltage dividing circuit can be used to obtain the first collected voltage or the fourth collected voltage, and the third sampling node in the third voltage dividing circuit can be used to obtain the third collected voltage or the sixth collected voltage. The voltage obtained by collection can be used to calculate the voltage across the first equivalent insulation resistance and the voltage across the second equivalent insulation resistance, and then the first equivalent insulation resistance and the second equivalent insulation resistance can be calculated, so as to determine whether the insulation state between the positive terminal and the second reference node and between the negative terminal and the second reference node is abnormal according to the resistance values of the two equivalent insulation resistances.

[0019] In some embodiments, the second voltage dividing circuit includes a third voltage dividing unit, a second detection unit, a fourth voltage dividing unit and a second switch, and the fourth voltage dividing circuit includes a fifth voltage dividing unit, a sixth voltage dividing unit and a third switch; the positive terminal is connected with a first end of the fifth voltage dividing unit and a first end of the sixth voltage dividing unit respectively, and a second end of the sixth voltage dividing unit is connected with a first end of the third switch; the second reference node is connected with a second end of the fifth voltage dividing unit, a second end of the third switch, a first end of the third voltage dividing unit and a first end of the fourth voltage dividing unit respectively, a second end of the fourth voltage dividing unit is connected with a first end of the second switch, a second end of the third voltage dividing unit is connected with a second end of the second switch and the first reference node respectively, a third end of the third voltage dividing unit is connected with the second detection unit, and a second sampling node is arranged in the second detection unit and used to obtain a second collected voltage or a fifth collected voltage.

[0020] According to the above technical means, the second sampling node in the second voltage dividing circuit can be used to obtain the second sampling voltage or the fifth sampling voltage, in combination with the first sampling voltage or the fourth sampling voltage obtained according to the first sampling node and the third sampling voltage or the sixth sampling voltage obtained according to the third sampling node, so as to calculate the voltage across the first equivalent insulation resistance and the voltage across the second equivalent insulation resistance, and then calculate the first equivalent insulation resistance and the second equivalent insulation resistance, so as to determine whether the insulation state between the positive terminal and the second reference node and between the negative terminal and the second reference node is abnormal according to the resistance values of the two equivalent insulation resistances.

[0021] In some embodiments, the insulation detection circuit is further configured to determine that the sampling voltage at the second sampling node is in a preset power supply range when the resistance value of the first equivalent insulation resistance is equal to the resistance value of the second equivalent insulation resistance; or determine that the sampling voltage at the second sampling node is greater than the preset power supply range when the resistance value of the first equivalent insulation resistance is greater than the resistance value of the second equivalent insulation resistance; or determine that the sampling voltage at the second sampling node is less than the preset power supply range when the resistance value of the first equivalent insulation resistance is less than the resistance value of the second equivalent insulation resistance.

[0022] According to the above technical means, the sampling voltage at the second sampling node can be used to indicate insulation abnormality according to the resistance value of the first equivalent insulation resistance and the resistance value of the second equivalent insulation resistance, so that the fault of the insulation detection circuit can be found in time.

[0023] In some embodiments, the insulation detection circuit further comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor; wherein: the first capacitor is connected between the positive terminal and the negative terminal; the second capacitor is connected between the positive terminal and the second reference node; the third capacitor is connected between the negative terminal and the second reference node; the fourth capacitor is connected between the negative terminal and the first reference node; and the fifth capacitor is connected between the first reference node and the second reference node.

[0024] According to the above technical means, the first capacitor can be an X capacitor, which can be used to eliminate differential mode interference and suppress high frequency noise and interference; and the second capacitor, the third capacitor, the fourth capacitor and the fifth capacitor can be Y capacitors, which can be used to eliminate common mode interference and suppress low frequency noise and protect electronic devices.

[0025] In some embodiments, the number of the first voltage dividing circuits is one or more; wherein each first voltage dividing circuit and the third voltage dividing circuit respectively form a voltage sampling circuit.

[0026] By means of the above technical means, when the first voltage sampling circuit and the third voltage sampling circuit are composed of the first voltage sampling circuit and the third voltage sampling circuit, the elements in the first voltage sampling circuit and the third voltage sampling circuit do not participate in the calculation of the equivalent insulation resistance, and the parallel connection of the plurality of first voltage sampling circuits does not change the resistance value of the equivalent insulation resistance. Here, a plurality of first voltage sampling circuits can be connected in parallel, so that the plurality of first voltage sampling circuits can be composed of a plurality of voltage sampling channels with the third voltage sampling circuit, thereby solving the problem of inconvenient expansion of the voltage sampling channel in the related art. In this way, the plurality of voltage sampling channels can be expanded as needed, thereby improving the expansion flexibility of the voltage sampling channel.

[0027] In a second aspect, the embodiments of the present disclosure provide an insulation detection method applied to an insulation detection circuit, the insulation detection circuit comprising a first voltage dividing circuit, a second voltage dividing circuit, a third voltage dividing circuit and a fourth voltage dividing circuit; the first voltage dividing circuit is provided with a first switch, the second voltage dividing circuit is provided with a second switch, and the fourth voltage dividing circuit is provided with a third switch; the first voltage dividing circuit is connected in series between a positive terminal and a first reference node, the fourth voltage dividing circuit is connected in series between the positive terminal and a second reference node, the second voltage dividing circuit is connected in series between the second reference node and the first reference node, and the third voltage dividing circuit is connected in series between a negative terminal and the first reference node; the method comprises:

[0028] When the first switch is closed and the second switch and the third switch are open, a first calculation voltage across the first equivalent insulation resistance and a second calculation voltage across the second equivalent insulation resistance are determined by the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit;

[0029] The opening and closing states of the second switch and the third switch are determined according to the first calculation voltage and the second calculation voltage, and a third calculation voltage across the first equivalent insulation resistance and a fourth calculation voltage across the second equivalent insulation resistance are determined by the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit;

[0030] The resistance values of the first equivalent insulation resistance and the second equivalent insulation resistance are determined according to the first calculation voltage and the third calculation voltage across the first equivalent insulation resistance and the second calculation voltage and the fourth calculation voltage across the second equivalent insulation resistance;

[0031] Whether the insulation states between the positive terminal and the second reference node and between the negative terminal and the second reference node are abnormal is determined according to the resistance values of the first equivalent insulation resistance and the second equivalent insulation resistance;

[0032] The first equivalent insulation resistance represents an equivalent resistance value between the positive terminal and the second reference node, and the second equivalent insulation resistance represents an equivalent resistance value between the negative terminal and the second reference node.

[0033] By means of the above technical means, the method applied to the insulation detection circuit can not only utilize the first voltage dividing circuit and the third voltage dividing circuit to sample voltage, but also utilize the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit and the fourth voltage dividing circuit to realize insulation detection, so that voltage sampling and insulation detection can be realized at the same time, the circuit structure capable of realizing multiple functional circuits is simplified, the cost is reduced, and the first calculation voltage and the second calculation voltage and the third calculation voltage and the fourth calculation voltage obtained according to the opening and closing states of the first switch, the second switch and the third switch can also be used to calculate the resistance value of the equivalent insulation resistance; in addition, when the first voltage dividing circuit and the third voltage dividing circuit are used to form a voltage sampling channel, the elements in the first voltage dividing circuit and the third voltage dividing circuit do not participate in the calculation of the equivalent insulation resistance, and the parallel connection of multiple first voltage dividing circuits does not change the resistance value of the equivalent insulation resistance. Here, multiple first voltage dividing circuits can be connected in parallel, so that the multiple first voltage dividing circuits and the third voltage dividing circuit can form multiple voltage sampling channels, thereby solving the problem of inconvenient expansion of the voltage sampling channel in the related art, and improving the expansion flexibility of the voltage sampling channel.

[0034] In some embodiments, the voltage collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit determines the first calculation voltage across the first equivalent insulation resistance and the second calculation voltage across the second equivalent insulation resistance, comprising: obtaining a first collected voltage through the first voltage dividing circuit, obtaining a second collected voltage through the second voltage dividing circuit, and obtaining a third collected voltage through the third voltage dividing circuit; determining the first calculation voltage across the first equivalent insulation resistance and the second calculation voltage across the second equivalent insulation resistance according to the first collected voltage, the second collected voltage and the third collected voltage.

[0035] By means of the above technical means, the first sampling node in the first voltage dividing circuit can be used to obtain the first collected voltage, the second sampling node in the second voltage dividing circuit can be used to obtain the second collected voltage, and the third sampling node in the third voltage dividing circuit can be used to obtain the third collected voltage. According to the collected voltages, the first calculation voltage across the first equivalent insulation resistance and the second calculation voltage across the second equivalent insulation resistance can be calculated, so that the calculation of the first equivalent insulation resistance and the second equivalent insulation resistance can be realized.

[0036] In some embodiments, the opening and closing states of the second switch and the third switch are determined according to the first calculation voltage and the second calculation voltage, comprising: when the first calculation voltage is greater than or equal to the second calculation voltage, determining that the second switch is closed and the third switch is opened; or when the first calculation voltage is less than the second calculation voltage, determining that the third switch is closed and the second switch is opened.

[0037] By the above technical means, the first calculated voltage and the second calculated voltage are compared to determine which of the second switch and the third switch is closed, so that the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance can be obtained more accurately, and the accuracy of calculating the equivalent insulation resistance is improved.

[0038] In some embodiments, the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance are determined by the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit, including: when the first switch and the second switch are closed and the third switch is open, the fourth collected voltage is obtained by the first voltage dividing circuit, the fifth collected voltage is obtained by the second voltage dividing circuit, the sixth collected voltage is obtained by the third voltage dividing circuit, and the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance are determined according to the fourth collected voltage, the fifth collected voltage and the sixth collected voltage; or when the first switch and the third switch are closed and the second switch is open, the fourth collected voltage is obtained by the first voltage dividing circuit, the fifth collected voltage is obtained by the second voltage dividing circuit, the sixth collected voltage is obtained by the third voltage dividing circuit, and the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance are determined according to the fourth collected voltage, the fifth collected voltage and the sixth collected voltage.

[0039] By the above technical means, in different switch states, the fourth collected voltage can be obtained according to the first sampling node in the first voltage dividing circuit, the fifth collected voltage can be obtained according to the second sampling node in the second voltage dividing circuit, and the sixth collected voltage can be obtained according to the third sampling node in the third voltage dividing circuit, and the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance can be calculated according to the collected voltages, so that the calculation of the first equivalent insulation resistance and the second equivalent insulation resistance can be realized.

[0040] In some embodiments, the second sampling node is arranged in the second voltage dividing circuit; the method further includes: when the resistance value of the first equivalent insulation resistance and the resistance value of the second equivalent insulation resistance are equal, determining that the sampling voltage at the second sampling node is in a preset power supply range; or when the resistance value of the first equivalent insulation resistance is greater than the resistance value of the second equivalent insulation resistance, determining that the sampling voltage at the second sampling node is greater than the preset power supply range; or when the resistance value of the first equivalent insulation resistance is less than the resistance value of the second equivalent insulation resistance, determining that the sampling voltage at the second sampling node is less than the preset power supply range.

[0041] According to the size between the resistance value of the first equivalent insulation resistance and the resistance value of the second equivalent insulation resistance, and the sampling voltage at the second sampling node, the insulation abnormal condition can be indicated, so that the fault of the insulation detection circuit can be found in time.

[0042] In some embodiments, the method further comprises connecting the positive pole of the high-voltage source to the positive terminal and the negative pole of the high-voltage source to the first reference node, connecting the positive pole of the high-precision multimeter to the positive terminal and the negative pole of the high-precision multimeter to the second reference node; adjusting the high-voltage source to output in a preset voltage range, and performing regression analysis on the voltage across the first equivalent insulation resistance and the reading of the high-precision multimeter to calibrate the first calculated voltage or the third calculated voltage.

[0043] By the above technical means, the voltage across the first equivalent insulation resistance is calibrated, which can overcome the influence of sampling error superposition, thereby improving the accuracy of insulation detection.

[0044] In some embodiments, according to the resistance value of the first equivalent insulation resistance and the resistance value of the second equivalent insulation resistance, it is determined whether the insulation state between the positive terminal and the second reference node and the insulation state between the negative terminal and the second reference node are abnormal, comprising: when the resistance value of the first equivalent insulation resistance is less than a preset insulation resistance threshold, it is determined that the insulation state between the positive terminal and the second reference node is insulation failure; when the resistance value of the first equivalent insulation resistance is greater than the preset insulation resistance threshold, it is determined that the insulation state between the positive terminal and the second reference node is normal insulation; and when the resistance value of the second equivalent insulation resistance is less than the preset insulation resistance threshold, it is determined that the insulation state between the negative terminal and the second reference node is insulation failure; when the resistance value of the second equivalent insulation resistance is greater than the preset insulation resistance threshold, it is determined that the insulation state between the negative terminal and the second reference node is normal insulation.

[0045] By means of the above technical means, according to the comparison result of the resistance value of the first equivalent insulation resistance and the preset insulation resistance threshold value, it can be determined whether the insulation state between the positive terminal and the second reference node is abnormal, for example, when the resistance value of the first equivalent insulation resistance is less than the preset insulation resistance threshold value, it is determined that the insulation state between the positive terminal and the second reference node is insulation failure; otherwise, when the resistance value of the first equivalent insulation resistance is greater than the preset insulation resistance threshold value, it is determined that the insulation state between the positive terminal and the second reference node is normal insulation; according to the comparison result of the resistance value of the second equivalent insulation resistance and the preset insulation resistance threshold value, it can be determined whether the insulation state between the negative terminal and the second reference node is abnormal, for example, when the resistance value of the second equivalent insulation resistance is less than the preset insulation resistance threshold value, it is determined that the insulation state between the negative terminal and the second reference node is insulation failure; otherwise, when the resistance value of the second equivalent insulation resistance is greater than the preset insulation resistance threshold value, it is determined that the insulation state between the negative terminal and the second reference node is normal insulation; thereby the insulation detection performance can be realized.

[0046] In a third aspect, the embodiments of the present disclosure provide a battery management system, comprising a control circuit and an insulation detection circuit as in the first aspect; wherein the control circuit is configured to provide a switching control signal to the insulation detection circuit to control the opening and closing states of the first switch, the second switch and the third switch.

[0047] By means of the above technical means, in the battery management system, the insulation detection circuit not only can use the first voltage dividing circuit and the third voltage dividing circuit for voltage sampling, but also can use the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit and the fourth voltage dividing circuit to realize insulation detection, so that voltage sampling and insulation detection can be realized at the same time; in addition, according to the opening and closing states of the first switch, the second switch and the third switch, the resistance value of the equivalent insulation resistance can also be calculated; and when the first voltage dividing circuit and the third voltage dividing circuit are used to form a voltage sampling channel, a plurality of first voltage dividing circuits can be connected in parallel here, and the plurality of first voltage dividing circuits and the third voltage dividing circuit can form a plurality of voltage sampling channels, thereby solving the problem of inconvenient expansion of voltage sampling channels in the related art.

[0048] This disclosure provides an insulation detection circuit, method, and battery management system. In the insulation detection circuit, a first voltage divider circuit includes a first switch, a second voltage divider circuit includes a second switch, and a fourth voltage divider circuit includes a third switch. Based on the open / closed states of the first, second, and third switches, the resistance values ​​of the first and second equivalent insulation resistances can be determined by the voltages collected by the first, second, and third voltage divider circuits. Then, based on the resistance values ​​of the first and second equivalent insulation resistances, it is determined whether the insulation state between the positive terminal and the second reference node, and between the negative terminal and the second reference node, is abnormal. In this way, not only can voltage sampling be performed using the first and third voltage divider circuits, but insulation detection can also be achieved using the first, second, third, and fourth voltage divider circuits. This allows for simultaneous voltage sampling and insulation detection, simplifying the circuit structure and reducing costs. Furthermore, based on the open / closed states of the first, second, and third switches, the equivalent insulation resistance can be calculated to determine if the insulation state between the positive and second reference nodes, as well as between the negative and second reference nodes, is abnormal. When the first and third voltage divider circuits form a voltage sampling channel, the components in these circuits do not participate in the calculation of the equivalent insulation resistance. Moreover, multiple first voltage divider circuits connected in parallel do not change the equivalent insulation resistance. Multiple first voltage divider circuits can be arbitrarily connected in parallel, thus forming multiple voltage sampling channels. This solves the problem of inconvenient voltage sampling channel expansion in related technologies, improves the flexibility of voltage sampling channel expansion, and ultimately enhances the overall performance of the insulation detection circuit. Attached Figure Description

[0049] Figure 1 is a schematic diagram of the composition structure of a high-voltage insulation detection circuit.

[0050] Figure 2 is a schematic diagram of the composition structure of a high-voltage insulation detection circuit.

[0051] Figure 3 is a schematic diagram of the composition structure of a high-voltage sampling circuit;

[0052] Figure 4 is a schematic diagram of the composition structure of an insulation detection circuit provided in an embodiment of this disclosure;

[0053] Figure 5 is a schematic diagram of the composition structure of an insulation detection circuit provided in an embodiment of this disclosure;

[0054] Figure 6 is a schematic diagram of the composition structure of an insulation detection circuit provided in an embodiment of this disclosure;

[0055] Figure 7 is a schematic diagram of the composition structure of an insulation detection circuit provided in an embodiment of this disclosure;

[0056] Fig. 8 is a schematic diagram of a structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0057] Fig. 9 is a schematic diagram of a structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0058] Fig. 10 is a schematic diagram of a structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0059] Fig. 11 is a schematic diagram of a structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0060] Fig. 12 is a schematic diagram of a structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0061] Fig. 13 is a schematic diagram of a structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0062] Fig. 14 is a schematic diagram of a detailed structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0063] Fig. 15 is a schematic diagram of a detailed structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0064] Fig. 16 is a schematic diagram of a structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0065] Fig. 17 is a schematic diagram of a detailed structure of an insulation detection circuit according to an embodiment of the present disclosure;

[0066] Fig. 18 is a schematic diagram of a flow of an insulation detection method according to an embodiment of the present disclosure;

[0067] Fig. 19 is a schematic diagram of a flow of an insulation detection method according to an embodiment of the present disclosure;

[0068] Fig. 20 is a schematic diagram of a structure of a battery management system according to an embodiment of the present disclosure;

[0069] Fig. 21 is a schematic diagram of a structure of a battery pack according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0070] In order to enable a person skilled in the art to more fully understand the features and technical contents of the embodiments of the present disclosure, the implementation of the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings, which are used only for reference and do not limit the embodiments of the present disclosure.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used in the description herein is for describing the embodiments of the disclosure only and is not intended to be limiting of the disclosure.

[0072] In the following description, reference is made to the "some embodiments", which describe a subset of all possible embodiments, but it is understood that "some embodiments" can be the same subset of all possible embodiments or a different subset of all possible embodiments, and can be combined with each other without conflict.

[0073] It should also be noted that the terms "first\second\third" involved in the embodiments of the disclosure are only used to distinguish similar objects, and do not represent a specific order of the objects. Understandably, "first\second\third" can be interchanged with a specific order or sequence as allowed, so that the embodiments of the disclosure described herein can be implemented in an order other than that illustrated or described herein.

[0074] New energy batteries are increasingly widely used in life and industry. For example, new energy vehicles equipped with batteries have been widely used, in addition, batteries are also increasingly used in energy storage fields and the like.

[0075] At present, new energy batteries are increasingly widely used in life and industry. New energy batteries are not only applied to energy storage power supply systems such as hydroelectric, thermal, wind and solar power stations, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also increasing.

[0076] In the embodiments of the disclosure, the battery can be a battery monomer. The battery monomer refers to a basic unit capable of realizing mutual conversion between chemical energy and electrical energy, and can be used to make a battery module or a battery pack, thereby being used to supply power to a power consumption device. The battery monomer can be a secondary battery, which refers to a battery monomer that can be activated by charging after discharging. The battery monomer can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead-acid battery, etc. Herein, this is not limited.

[0077] In the embodiments of the disclosure, the battery can also be a single physical module including one or more battery monomers to provide higher voltage and capacity. When there are multiple battery monomers, the multiple battery monomers are connected in series, in parallel or in a mixed manner through a busbar component.

[0078] With the wide application of batteries in the field of power batteries and energy storage, electric vehicles replacing fuel vehicles have become the trend of the development of the automobile industry, and the endurance mileage, service life and safety of the battery pack are particularly important for the use of electric vehicles. As one of the key components of electric vehicles, the safety of high-voltage electricity of the power battery pack must be one of the primary considerations of the power battery system. Therefore, the detection of the insulation performance of the electric vehicle is an essential part of the design.

[0079] As the electric motor of the electric vehicle provides electric energy, for the battery management system (BMS), high-voltage sampling and insulation detection are the basic functions of the BMS, which play a crucial role in ensuring the safe operation of the battery. Currently, the key devices in the BMS circuit include switching elements such as relays, metal-oxide semiconductor field-effect transistors (MOSFETs or simply MOS tubes), etc., so the common insulation detection methods for BMS mainly include the 4MOS method, the 2MOS method and the Y-bridge method, which meet the high-voltage insulation detection requirements, and these methods usually design two different reference nodes for analog voltage sampling.

[0080] In one possible implementation, as shown in FIG. 1, a common 2MOS high-voltage insulation detection method is provided, which is characterized by flexible expansion of the voltage sampling channel and high insulation detection accuracy. In FIG. 1, the voltage sampling channel composed of the first switch S1, the first resistor R1 and the second resistor R2 is used for high-voltage sampling between the positive terminal HV+ and the negative terminal HV-, and this voltage sampling channel is independent of other elements and can be arbitrarily expanded, thereby realizing flexible expansion of the voltage sampling channel. In addition, in actual applications, the reference node of the microcontroller unit (MCU) is usually GND, and its analog channel can meet the voltage sampling requirements of the second sampling node V2; however, for the voltage sampling of the first sampling node V1 and the third sampling node V3, since the reference node is the negative terminal HV-, and the reference node of the MCU is GND, an isolation component such as an isolation communication chip or an isolation power supply needs to be added between the two, so as to isolate the negative terminal HV- from GND, i.e. an additional isolation sampling circuit with the negative terminal HV- as the reference node (not shown in the figure) needs to be added. In general, this part of the isolation sampling circuit is an important part of the cost of the BMS and is one of the key factors that increase the complexity of the BMS circuit structure and cause electromagnetic interference (EMI) problems. In short, the high-voltage insulation detection circuit shown in FIG. 1 has the problems of high cost and complex circuit structure.

[0081] In another possible implementation, to solve the problems of the high-voltage insulation detection method described above, some researchers propose an insulation detection circuit based on the same reference potential, as shown in FIG. 2. This method can effectively reduce the cost of insulation detection. In FIG. 2, the output signal Ua of the first follower U1 is used to obtain the sampling voltage between the positive terminal HV+ and the reference node GND, and the output signal Uc of the second follower U2 is used to obtain the sampling voltage between the negative terminal HV- and the reference node GND. However, since the high-voltage sampling in FIG. 2 needs to take the negative terminal HV- as the reference node, this method cannot meet the demand of high-voltage sampling. Therefore, this paper proposes a high-voltage sampling circuit as shown in FIG. 3. In FIG. 3, the output signal AI_HV_MCU of the third follower U3 can be used to obtain the sampling voltage between the positive terminal HV+ and the negative terminal HV-. However, considering the need for isolation between high voltage and low voltage, this high-voltage sampling circuit needs to use four switches (first switch S1, second switch S2, third switch S3, and fourth switch S4). Since these four switches are high-voltage light MOS tubes or relays, and the control signals of the first switch S1 and the second switch S2 need to occupy one way of GPIO resources, and the control signals of the third switch S3 and the fourth switch S4 need to occupy one way of GPIO resources, that is, more than two GPIO resources of the MCU are needed at the same time, so when expanding the multi-channel voltage sampling channel, its cost will be greatly improved. In addition, due to the existence of the leakage current of the first capacitor C1, the high-voltage sampling accuracy will be difficult to guarantee. In short, the high-voltage insulation detection circuits shown in FIG. 2 and FIG. 3 have the problem of inconvenient expansion of voltage sampling channels, and cannot meet the demand of multi-voltage sampling channels.

[0082] Based on this, the embodiment of the disclosure provides an insulation detection circuit, method and battery management system. In the insulation detection circuit, not only voltage sampling can be performed by using the first voltage dividing circuit and the third voltage dividing circuit, but also insulation detection can be realized by using the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit and the fourth voltage dividing circuit, so that voltage sampling and insulation detection can be realized at the same time, the circuit structure capable of realizing multiple functional circuits is simplified, and the cost is reduced. According to the opening and closing states of the first switch, the second switch and the third switch, the resistance value of the equivalent insulation resistance can also be calculated to determine whether the insulation states between the positive terminal and the second reference node and between the negative terminal and the second reference node are abnormal. When the first voltage dividing circuit and the third voltage dividing circuit are used to form a voltage sampling channel, the elements in the first voltage dividing circuit and the third voltage dividing circuit do not participate in the calculation of the equivalent insulation resistance, and the parallel connection of multiple first voltage dividing circuits does not change the resistance value of the equivalent insulation resistance. Here, multiple first voltage dividing circuits can be connected in parallel, so that the multiple first voltage dividing circuits can form multiple voltage sampling channels with the third voltage dividing circuit, solve the problem of inconvenient expansion of the voltage sampling channel in the related art, improve the expansion flexibility of the voltage sampling channel, and further improve the overall performance of the insulation detection circuit.

[0083] The various embodiments of the disclosure will be described in detail below with reference to the accompanying drawings.

[0084] In an embodiment of the disclosure, FIG. 4 is a component structure diagram one of an insulation detection circuit provided by the embodiment of the disclosure. As shown in FIG. 4, the insulation detection circuit 40 can include a first voltage dividing circuit 401, a second voltage dividing circuit 402, a third voltage dividing circuit 403 and a fourth voltage dividing circuit 404, wherein: the first switch is arranged in the first voltage dividing circuit 401, the second switch is arranged in the second voltage dividing circuit 402, the third switch is arranged in the fourth voltage dividing circuit 404, the first voltage dividing circuit 401 is connected in series between the positive terminal HV+ and the first reference node GND, the fourth voltage dividing circuit 404 is connected in series between the positive terminal HV+ and the second reference node Ground, the second voltage dividing circuit 402 is connected in series between the second reference node Ground and the first reference node GND, and the third voltage dividing circuit 403 is connected in series between the negative terminal HV- and the first reference node GND.

[0085] In some embodiments, the insulation detection circuit 40 is configured to determine the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn based on the open / close states of the first switch, the second switch and the third switch, and the voltages collected by the first voltage dividing circuit 401, the second voltage dividing circuit 402 and the third voltage dividing circuit 403; and determine whether the insulation states between the positive terminal and the second reference node and between the negative terminal and the second reference node are abnormal according to the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn. The first equivalent insulation resistance Rp represents the equivalent resistance value between the positive terminal and the second reference node, and the second equivalent insulation resistance Rn represents the equivalent resistance value between the negative terminal and the second reference node.

[0086] In the embodiments of the present disclosure, the insulation detection circuit 40 can be applied to a high-voltage scenario. In the field, the concepts of high voltage and low voltage are relative. For example, the voltage of a device to ground is 1000V or below, which can be referred to as low voltage; the voltage of a device to ground is 1000V or above, which can be referred to as high voltage. Here, high voltage can also be referred to as "high voltage", which generally refers to bus voltage, battery voltage, etc. above 1000V, which is not specifically limited here. In addition, in the embodiments of the present disclosure, the insulation detection circuit 40 can also be applied to a power battery scenario. For example, in an electric vehicle, the voltage range can be 60V-1500V, which is not specifically limited here.

[0087] In the embodiments of the present disclosure, for the positive terminal and the negative terminal, for example, if the input terminal of the insulation detection circuit 40 is connected to a battery, the positive terminal HV+ can be connected to the positive terminal of the battery, and the negative terminal HV- can be connected to the negative terminal of the battery. Alternatively, if the input terminal of the insulation detection circuit 40 is connected to a DC bus, the positive terminal HV+ can be connected to the positive terminal of the DC bus, and the negative terminal HV- can be connected to the negative terminal of the DC bus, which is not specifically limited here.

[0088] That is, in the embodiments of the present disclosure, the insulation detection circuit 40 can perform voltage sampling through the first voltage dividing circuit 401 and the third voltage dividing circuit 403, and can also perform insulation detection through the first voltage dividing circuit 401, the second voltage dividing circuit 402, the third voltage dividing circuit 403 and the fourth voltage dividing circuit 404, that is, voltage sampling and insulation detection can be realized at the same time, thereby simplifying the circuit structure of the circuit capable of realizing multiple functions and reducing the cost; and according to the open / close states of the first switch, the second switch and the third switch, the resistance values of the equivalent insulation resistances can also be calculated to determine whether the insulation states between the positive terminal HV+ and the second reference node Ground and between the negative terminal HV- and the second reference node Ground are abnormal.

[0089] It should be further noted that, in the embodiments of the present disclosure, for the first reference node GND and the second reference node Ground, the first reference node GND refers to the negative electrode of a direct current-direct current (DC-DC) circuit connected to low-voltage power supply, and the negative electrode of the DC-DC circuit is the same connection as the ground of a chip (for example, an MCU); the second reference node Ground generally refers to the ground, for example, the Ground of a vehicle is connected to the outer shell of the vehicle and is a metal that can be touched by a person; the Ground of an energy storage system is connected to the outer shell of an electrical cabinet and is also a metal that can be touched by a person. That is, although both are ground terminals, GND and Ground represent different ground terminals.

[0090] In some embodiments, based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 5, the insulation detection circuit 40 includes a plurality of first voltage division circuits (401-1, 401-2, …, 401-K), K being a positive integer.

[0091] In the embodiments of the present disclosure, the number of first voltage division circuits is one or more, and each first voltage division circuit and the third voltage division circuit can constitute a voltage sampling circuit (or referred to as a voltage sampling channel). In addition, for voltage sampling between the positive terminal HV+ and the negative terminal HV-, it can be divided into two sections: the first voltage division circuit between the positive terminal HV+ and the first reference node GND, and the third voltage division circuit between the negative terminal HV- and the first reference node GND, that is, each voltage sampling circuit is composed of two parts of the first voltage division circuit and the third voltage division circuit, so it can also be referred to as a segmented voltage sampling circuit.

[0092] In the embodiments of the present disclosure, the elements in the first voltage division circuit and the third voltage division circuit do not participate in the calculation of the equivalent insulation resistance, and the parallel connection of a plurality of first voltage division circuits will not change the resistance value of the equivalent insulation resistance, so that any number of voltage sampling channels can be expanded.

[0093] That is, in the embodiments of the present disclosure, when a first voltage division circuit and a third voltage division circuit are used to constitute a voltage sampling circuit (i.e., a voltage sampling channel), the elements in the first voltage division circuit and the third voltage division circuit do not participate in the calculation of the equivalent insulation resistance, and the parallel connection of a plurality of first voltage division circuits will not change the resistance value of the equivalent insulation resistance, so that a plurality of first voltage division circuits can be connected in parallel, and the plurality of first voltage division circuits and the third voltage division circuit can constitute a plurality of voltage sampling channels, solving the problem of inconvenient expansion of voltage sampling channels in the related art. In this way, the number of voltage sampling channels can be expanded as needed, improving the expansion flexibility of the voltage sampling channels.

[0094] In some embodiments, based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 6, the first voltage dividing circuit 401 can include a first voltage dividing unit 511 and a first switch S1.

[0095] In the embodiments of the present disclosure, for the first voltage dividing circuit 401, a first end of the first switch S1 is connected with the positive terminal HV+, a second end of the first switch S1 is connected with a first end of the first voltage dividing unit 511, and a second end of the first voltage dividing unit 511 is connected with the first reference node GND and a first end of the third voltage dividing circuit 403 respectively. The first voltage dividing unit 511 is provided with a first sampling node V1 for obtaining the first acquisition voltage or the fourth acquisition voltage.

[0096] In a possible implementation, for the first voltage dividing unit 511, the voltage sampling of the first sampling node V1 can be realized by resistance voltage division. Based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 7, the first voltage dividing circuit 401 can include a fourth resistor R4, a ninth resistor R9 and the first switch S1.

[0097] In the embodiments of the present disclosure, for the first voltage dividing circuit 401, a first end of the first switch S1 is connected with the positive terminal HV+, a second end of the first switch S1 is connected with a first end of the ninth resistor R9, a second end of the ninth resistor R9 is connected with a first end of the fourth resistor R4, and a second end of the fourth resistor R4 is connected with the first reference node GND and a first end of the third voltage dividing circuit 403 respectively.

[0098] In the embodiments of the present disclosure, the fourth resistor R4 and the ninth resistor R9 constitute the first voltage dividing unit 511. The fourth resistor R4 and the ninth resistor R9 are connected in series, and the first sampling node V1 is led out on a connecting line between the fourth resistor R4 and the ninth resistor R9 for obtaining the first acquisition voltage or the fourth acquisition voltage.

[0099] In some embodiments, based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 8, the third voltage dividing circuit 403 includes a second voltage dividing unit 531 and a first detection unit 532.

[0100] In the embodiments of the present disclosure, for the third voltage dividing circuit 403, a first end of the second voltage dividing unit 531 is connected with the first reference node GND, a second end of the second voltage dividing unit 531 is connected with the negative terminal HV-, and a third end of the second voltage dividing unit 531 is connected with the first detection unit 532. The first detection unit 532 is provided with a third sampling node V3 for obtaining the third acquisition voltage or the sixth acquisition voltage.

[0101] In a possible implementation, for the second voltage dividing unit 531, the voltage sampling of the third sampling node V3 can be realized by resistance voltage division in combination with the first detection unit 532. Based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 9, the third voltage dividing circuit 403 can include the first resistor R1, the second resistor R2, the sixth resistor R6, the fifth resistor R5, and the first diode D1.

[0102] In the embodiments of the present disclosure, for the third voltage dividing circuit 403, the first resistor R1, the second resistor R2, and the sixth resistor R6 constitute the second voltage dividing unit 531, and the fifth resistor R5 and the first diode D1 constitute the first detection unit 532. The fifth resistor R5 and the first diode D1 are connected in series, the first resistor R1 and the sixth resistor R6 are connected in series, the second resistor R2 is connected in parallel across the first resistor R1 and the sixth resistor R6, the connection line between the first resistor R1 and the sixth resistor R6 is connected to the connection line between the fifth resistor R5 and the first diode D1, and the third sampling node V3 is led out on the connection line between the fifth resistor R5 and the first diode D1. In addition, in FIG. 9, the first end of the fifth resistor R5 is connected to the first power supply, the second end of the first diode D1 is connected to the first reference node GND, the second end of the fifth resistor R5 is connected to the first end of the first diode D1 and the third sampling node V3 is led out, for obtaining the third acquisition voltage or the sixth acquisition voltage.

[0103] In some embodiments, based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 10, the second voltage dividing circuit 402 can include the third voltage dividing unit 521, the second detection unit 522, the fourth voltage dividing unit 523, and the second switch S2.

[0104] In the embodiments of the present disclosure, for the second voltage dividing circuit 402, the second reference node Ground is connected to the first end of the third voltage dividing unit 521 and the first end of the fourth voltage dividing unit 523 respectively, the second end of the fourth voltage dividing unit 523 is connected to the first end of the second switch S2, the second end of the third voltage dividing unit 521 is connected to the second end of the second switch S2 and the first reference node GND respectively, the third end of the third voltage dividing unit 521 is connected to the second detection unit 522, and the second sampling node V2 is arranged in the second detection unit 522, for obtaining the second acquisition voltage or the fifth acquisition voltage.

[0105] In a possible implementation, for the third voltage dividing unit 521, the voltage sampling of the second sampling node V2 can be realized by resistance voltage division in combination with the second detection unit 522. Based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 11, the second voltage dividing circuit 402 can include the third resistor R3, the seventh resistor R7, the thirteenth resistor R13, the second diode D2, the eighth resistor R8, and the second switch S2.

[0106] In the embodiment of the present disclosure, for the second voltage dividing circuit 402, the third resistor R3 and the seventh resistor R7 constitute the third voltage dividing unit 521, the thirteenth resistor R13 and the second diode D2 constitute the second detection unit 522, and the eighth resistor R8 constitutes the fourth voltage dividing unit 523. The seventh resistor R7 and the third resistor R3 are connected in series, the thirteenth resistor R13 and the second diode D2 are connected in series, the eighth resistor R8 and the second switch S2 are connected in series, the eighth resistor R8 and the second switch S2 are connected in parallel across the seventh resistor R7 and the third resistor R3, the connection line between the seventh resistor R7 and the third resistor R3 is connected to the connection line between the thirteenth resistor R13 and the second diode D2, and the second sampling node V2 is led out on the connection line between the thirteenth resistor R13 and the second diode D2, for obtaining the second acquisition voltage or the fifth acquisition voltage.

[0107] In some embodiments, based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 12, the fourth voltage dividing circuit 404 can include a fifth voltage dividing unit 541, a sixth voltage dividing unit 542, and a third switch S3.

[0108] In the embodiment of the present disclosure, for the fourth voltage dividing circuit 404, the positive terminal HV+ is connected to the first end of the fifth voltage dividing unit 541 and the first end of the sixth voltage dividing unit 542 respectively, and the second end of the sixth voltage dividing unit 542 is connected to the first end of the third switch S3; the second reference node Ground is connected to the second end of the fifth voltage dividing unit 541 and the second end of the third switch S3 respectively.

[0109] In a possible implementation, based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 13, the fourth voltage dividing circuit 404 can include a tenth resistor R10, a fourteenth resistor R14, and a third switch S3.

[0110] In the embodiment of the present disclosure, for the fourth voltage dividing circuit 404, the tenth resistor R10 constitutes the fifth voltage dividing unit 541, and the fourteenth resistor R14 constitutes the sixth voltage dividing unit 542. The fourteenth resistor R14 and the third switch S3 are connected in series, and the tenth resistor R10 is connected in parallel across the fourteenth resistor R14 and the third switch S3. In the fourth voltage dividing circuit 404, when calculating the resistance value of the equivalent insulation resistance, the closing and opening of the third switch S3 can be controlled to change the series-parallel connection of the resistors in the insulation detection process, so that the fourth acquisition voltage, the fifth acquisition voltage, and the sixth acquisition voltage collected are changed, and the calculation accuracy of the equivalent insulation resistance is improved.

[0111] In a specific embodiment, taking FIG. 6, FIG. 8, FIG. 10 and FIG. 12 as examples, FIG. 14 is a detailed structure diagram of an insulation detection circuit provided by the embodiment of the present disclosure. As shown in FIG. 14, the first voltage division circuit 401 includes a first voltage division unit 511 and a first switch S1, the third voltage division circuit 403 includes a second voltage division unit 531 and a first detection unit 532, the second voltage division circuit 402 can include a third voltage division unit 521, a second detection unit 522, a fourth voltage division unit 523 and a second switch S2, and the fourth voltage division circuit 404 can include a fifth voltage division unit 541, a sixth voltage division unit 542 and a third switch S3. Wherein:

[0112] In the first voltage division circuit 401, the first end of the first switch S1 is connected with the positive terminal HV+, the second end of the first switch S1 is connected with the first end of the first voltage division unit 511, the second end of the first voltage division unit 511 is connected with the first reference node GND and the first end of the second voltage division unit 531 respectively, and the first voltage division unit 511 is provided with a first sampling node V1 for obtaining a first acquisition voltage or a fourth acquisition voltage.

[0113] In the second voltage division circuit 402 and the fourth voltage division circuit 404, the positive terminal HV+ is connected with the first end of the fifth voltage division unit 541 and the first end of the sixth voltage division unit 542 respectively, and the second end of the sixth voltage division unit 542 is connected with the first end of the third switch S3; the second reference node Ground is connected with the second end of the fifth voltage division unit 541, the second end of the third switch S3, the first end of the third voltage division unit 521 and the first end of the fourth voltage division unit 523 respectively, the second end of the fourth voltage division unit 523 is connected with the first end of the second switch S2, the second end of the third voltage division unit 521 is connected with the second end of the second switch S2 and the first reference node GND respectively, the third end of the third voltage division unit 521 is connected with the second detection unit 522, and the second detection unit 522 is provided with a second sampling node V2 for obtaining a second acquisition voltage or a fifth acquisition voltage.

[0114] In addition, in the third voltage division circuit 403, the second end of the second voltage division unit 531 is connected with the negative terminal HV-, the third end of the second voltage division unit 531 is connected with the first detection unit 532, and the first detection unit 532 is provided with a third sampling node V3 for obtaining a third acquisition voltage or a sixth acquisition voltage.

[0115] It should be noted that, in the embodiment of the present disclosure, the first acquisition voltage can be represented by U 11 , the second acquisition voltage can be represented by U 21 , the third acquisition voltage can be represented by U 31 , the fourth acquisition voltage can be represented by U 12 , and the fifth acquisition voltage can be represented by U 22The sixth acquisition voltage can be represented as U 32 .

[0116] It should be further noted that in the embodiments of the present disclosure, the first acquisition voltage U 11 , the second acquisition voltage U 21 and the third acquisition voltage U 31 may be voltages acquired at the first sampling node V1, the second sampling node V2 and the third sampling node V3 respectively based on a first condition; the fourth acquisition voltage U 12 , the fifth acquisition voltage U 22 and the sixth acquisition voltage U 32 may be voltages acquired at the first sampling node V1, the second sampling node V2 and the third sampling node V3 respectively based on a second condition.

[0117] The first condition and the second condition can be different. For example, the first condition can be that the first switch S1 is closed, and the second switch S2 and the third switch S3 are open; the second condition can be that the first switch S1 and the second switch S2 are closed, and the third switch S3 is open; or the first switch S1 and the third switch S3 are closed, and the second switch S2 is open.

[0118] In this way, based on the opening and closing states of the first switch S1, the second switch S2 and the third switch S3, the resistance series-parallel connection in the insulation detection process can be changed, and then the acquisition voltages obtained are changed, so that the calculation of the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn according to the acquisition voltages can improve the calculation accuracy of the equivalent insulation resistance.

[0119] In another specific embodiment, taking FIG. 7, FIG. 9, FIG. 11 and FIG. 13 as examples, FIG. 15 is a detailed structure schematic diagram two of an insulation detection circuit provided by the embodiments of the present disclosure. As shown in FIG. 15, the first voltage dividing circuit 401 can include the fourth resistor R4, the ninth resistor R9 and the first switch S1, the second voltage dividing circuit 402 can include the third resistor R3, the seventh resistor R7, the thirteenth resistor R13, the second diode D2, the eighth resistor R8 and the second switch S2, the third voltage dividing circuit 403 can include the first resistor R1, the second resistor R2, the sixth resistor R6, the fifth resistor R5 and the first diode D1, and the fourth voltage dividing circuit 404 can include the tenth resistor R10, the fourteenth resistor R14 and the third switch S3.

[0120] In the embodiment of the present disclosure, for the first voltage dividing circuit 401, the fourth resistor R4 and the ninth resistor R9 constitute the first voltage dividing unit 511. The fourth resistor R4 and the ninth resistor R9 are connected in series, and the first sampling node V1 is led out on the connection line between the fourth resistor R4 and the ninth resistor R9. For the second voltage dividing circuit 402, the third resistor R3 and the seventh resistor R7 constitute the third voltage dividing unit 521, the thirteenth resistor R13 and the second diode D2 constitute the second detection unit 522, and the eighth resistor R8 constitutes the fourth voltage dividing unit 523. The seventh resistor R7 and the third resistor R3 are connected in series, the thirteenth resistor R13 and the second diode D2 are connected in series, the eighth resistor R8 and the second switch S2 are connected in series, and the eighth resistor R8 and the second switch S2 are connected in parallel across the seventh resistor R7 and the third resistor R3. The connection line between the seventh resistor R7 and the third resistor R3 is connected to the connection line between the thirteenth resistor R13 and the second diode D2, and the second sampling node V2 is led out on the connection line between the thirteenth resistor R13 and the second diode D2. For the third voltage dividing circuit 403, the first resistor R1, the second resistor R2 and the sixth resistor R6 constitute the second voltage dividing unit 531, and the fifth resistor R5 and the first diode D1 constitute the first detection unit 532. The fifth resistor R5 and the first diode D1 are connected in series, the first resistor R1 and the sixth resistor R6 are connected in series, the second resistor R2 is connected in parallel across the first resistor R1 and the sixth resistor R6, the connection line between the first resistor R1 and the sixth resistor R6 is connected to the connection line between the fifth resistor R5 and the first diode D1, and the third sampling node V3 is led out on the connection line between the fifth resistor R5 and the first diode D1. For the fourth voltage dividing circuit 404, the tenth resistor R10 constitutes the fifth voltage dividing unit 541, and the fourteenth resistor R14 constitutes the sixth voltage dividing unit 542. The fourteenth resistor R14 and the third switch S3 are connected in series, and the tenth resistor R10 is connected in parallel across the fourteenth resistor R14 and the third switch S3.

[0121] It should be noted that, in the embodiment of the present disclosure, for the first detection unit 532, the first end of the fifth resistor R5 is connected to the first power supply, the second end of the fifth resistor R5 is connected to the first end of the first diode D1 and leads out the third sampling node V3, and the second end of the first diode D1 is connected to the first reference node GND. For the second detection unit 522, the first end of the thirteenth resistor R13 is connected to the second power supply, the second end of the thirteenth resistor R13 is connected to the first end of the second diode D2 and leads out the second sampling node V2, and the second end of the second diode D2 is connected to the first reference node GND.

[0122] It should be further noted that, in the embodiment of the present disclosure, the first power supply and the second power supply can be the same or different. For example, the first power supply and the second power supply are the same, and both can be represented by VCC.

[0123] It should be further noted that in the embodiments of the present disclosure, the first diode D1 and the second diode D2 mainly play a role in voltage stabilization. Since the second sampling node V2 and the third sampling node V3 are directly connected to the control chip such as MCU and single-chip microcomputer, if there is a pulse or voltage that is too high at this position, the control chip is likely to be damaged, and therefore the first diode D1 and the second diode D2 are needed to perform voltage stabilization.

[0124] In some embodiments, the insulation detection circuit 40 is configured to, when the first switch S1 is closed and the second switch S2 and the third switch S3 are opened, acquire a first collected voltage U 11 via the first voltage dividing circuit 401, acquire a second collected voltage U 21 via the second voltage dividing circuit 402, acquire a third collected voltage U 31 via the third voltage dividing circuit 403, and determine a first calculated voltage U 11 across the first equivalent insulation resistance Rp and a second calculated voltage U 21 across the second equivalent insulation resistance Rn according to the first collected voltage U 31 , the second collected voltage U p1 and the third collected voltage U n1 .

[0125] In the embodiments of the present disclosure, taking FIG. 15 as an example, when the first switch S1 is closed and the second switch S2 and the third switch S3 are opened, a first collected voltage U 11 is acquired via the first voltage dividing circuit 401, specifically, a voltage collected at the first sampling node V1; a second collected voltage U 21 is acquired via the second voltage dividing circuit 402, specifically, a voltage collected at the second sampling node V2; and a third collected voltage U 31 is acquired via the third voltage dividing circuit 403, specifically, a voltage collected at the third sampling node V3. According to the first collected voltage U 11 , the second collected voltage U 21 and the third collected voltage U 31 , and then the first calculated voltage U p1 across the first equivalent insulation resistance Rp and the second calculated voltage U n1 across the second equivalent insulation resistance Rn are calculated in combination with the following formula:

[0126] wherein R1 represents a resistance value of the first resistor R1, R3 represents a resistance value of the third resistor R3, R4 represents a resistance value of the fourth resistor R4, R5 represents a resistance value of the fifth resistor R5, R6 represents a resistance value of the sixth resistor R6, R7 represents a resistance value of the seventh resistor R7, R9 represents a resistance value of the ninth resistor R9, R 13 represents a resistance value of the thirteenth resistor R13, V CC represents a supply voltage of the power supply VCC.

[0127] Thus, when the first switch S1 is closed and the second switch S2 and the third switch S3 are open, according to the formulas (1) and (2), the first calculated voltage U p1 across the first equivalent insulation resistor Rp and the second calculated voltage U n1 across the second equivalent insulation resistor Rn can be calculated.

[0128] In some embodiments, the insulation detection circuit 40 is further configured to determine the opening and closing states of the second switch S2 and the third switch S3 according to the first calculated voltage U p1 and the second calculated voltage U n1 , acquire the fourth collected voltage U 12 through the first voltage dividing circuit 401, acquire the fifth collected voltage U 22 through the second voltage dividing circuit 402, acquire the sixth collected voltage U 32 through the third voltage dividing circuit 403, and determine the third calculated voltage U 12 across the first equivalent insulation resistor Rp and the fourth calculated voltage U 22 across the second equivalent insulation resistor Rn according to the fourth collected voltage U 32 , the fifth collected voltage U p2 and the sixth collected voltage U n2 .

[0129] In the embodiments of the present disclosure, for the opening and closing states of the second switch S2 and the third switch S3, specifically, when the first calculated voltage U p1 is greater than or equal to the second calculated voltage U n1 , it is determined that the second switch S2 is closed and the third switch S3 is open; or when the first calculated voltage U p1 is less than the second calculated voltage U n1 , it is determined that the third switch S3 is closed and the second switch S2 is open.

[0130] That is, by comparing the first calculated voltage U p1 and the second calculated voltage U n1 , it is determined which of the second switch S2 and the third switch S3 is closed. For example, if U p1 ≥ U n1Then, the second switch S2 is closed. At this time, the switch states are: the first switch S1 and the second switch S2 are closed, and the third switch S3 is open. Then, based on the fourth sampling voltage U obtained by the first voltage divider circuit 401, the second voltage divider circuit 402, and the third voltage divider circuit 403... 12 Fifth voltage acquisition U 22 and the sixth acquisition voltage U 32 To determine the third calculated voltage U across the first equivalent insulation resistance Rp. p2 The fourth calculated voltage U across the second equivalent insulation resistance Rn n2 Or, if U p1 n1 Then, the third switch S3 is closed. At this time, the switch states are: the first switch S1 and the third switch S3 are closed, and the second switch S2 is open. Then, based on the fourth sampling voltage U obtained by the first voltage divider circuit 401, the second voltage divider circuit 402, and the third voltage divider circuit 403... 12 Fifth voltage acquisition U 22 and the sixth acquisition voltage U 32 To determine the third calculated voltage U across the first equivalent insulation resistance Rp. p2 The fourth calculated voltage U across the second equivalent insulation resistance Rn n2 .

[0131] In one possible implementation, taking Figure 15 as an example, if U p1 ≥U n1 Then, the first switch S1 and the second switch S2 are closed, and the third switch S3 is open. In this case, the fourth voltage U is collected. 12 Specifically, this refers to the voltage sampled at the first sampling node V1 and the fifth sampling voltage U under this switching state. 22 Specifically, this refers to the voltage sampled at the second sampling node V2 under this switching state, and the sixth sampling voltage U. 32 Specifically, this refers to the voltage sampled at the third sampling node V3 under this switching state. Based on the fourth sampling voltage U... 12 Fifth voltage acquisition U 22 and the sixth acquisition voltage U 32 Then, the third calculated voltage U across the first equivalent insulation resistance Rp is calculated using the following formula. p2 The fourth calculated voltage U across the second equivalent insulation resistance Rn n2 The formula is shown below:

[0132] ​Wherein, R1 represents the resistance value of the first resistor R1, R3 represents the resistance value of the third resistor R3, R4 represents the resistance value of the fourth resistor R4, R5 represents the resistance value of the fifth resistor R5, R6 represents the resistance value of the sixth resistor R6, R7 represents the resistance value of the seventh resistor R7, R9 represents the resistance value of the ninth resistor R9, R 13 represents the resistance value of the thirteenth resistor R13, V CC represents the supply voltage of the power supply VCC.

[0133] In another possible implementation, still taking FIG. 15 as an example, if U p1 <U n1 , then the first switch S1 and the third switch S3 are closed, and the second switch S2 is disconnected, in which case the fourth collected voltage U 12 Specifically, the voltage collected at the first sampling node V1 in this switch state, the fifth collected voltage U 22 Specifically, the voltage collected at the second sampling node V2 in this switch state, the sixth collected voltage U 32 Specifically, the voltage collected at the third sampling node V3 in this switch state. At this time, according to the fourth collected voltage U 12 , the fifth collected voltage U 22 , and the sixth collected voltage U 32 , and in combination with the above formulas (3) and (4), the third calculated voltage U p2 across the first equivalent insulation resistor Rp and the fourth calculated voltage U n2 across the second equivalent insulation resistor Rn can also be calculated.

[0134] In this way, after the first calculated voltage U p1 across the first equivalent insulation resistor Rp and the third calculated voltage U p2 across the second equivalent insulation resistor Rn are calculated, and the second calculated voltage U n1 across the first equivalent insulation resistor Rp and the fourth calculated voltage U n2 across the second equivalent insulation resistor Rn are calculated, the resistance value of the first equivalent insulation resistor Rp and the resistance value of the second equivalent insulation resistor Rn can be solved according to the simultaneous equations.

[0135] In some embodiments, the insulation detection circuit 40 is further configured to determine the resistance value of the first equivalent insulation resistor Rp and the resistance value of the second equivalent insulation resistor Rn according to the first calculated voltage U p1 across the first equivalent insulation resistor Rp and the third calculated voltage U p2 across the second equivalent insulation resistor Rn, and the second calculated voltage U n1 across the first equivalent insulation resistor Rp and the fourth calculated voltage U n2 across the second equivalent insulation resistor Rn.

[0136] In the embodiments of the present disclosure, the resistance value of the equivalent insulation resistance can be calculated based on the Kirchhoff's law. The Kirchhoff's law includes Kirchhoff's Current Law (KCL) and Kirchhoff Voltage Laws (KVL). Here, the Kirchhoff's equation can be solved with the second reference node Ground, specifically, the formulas (1)-(4) are solved, and the final equivalent insulation resistance calculation formula is as follows:

[0137] In this way, after obtaining the acquisition voltages in different switch states, the first calculation voltage U p1 across the first equivalent insulation resistance Rp and the second calculation voltage U n1 across the second equivalent insulation resistance Rn can be calculated according to the obtained acquisition voltages. p2 The third calculation voltage U n2 across the first equivalent insulation resistance Rp and the fourth calculation voltage U across the second equivalent insulation resistance Rn can be calculated according to the obtained acquisition voltages.

[0138] In some embodiments, after obtaining the resistance value of the first equivalent insulation resistance Rp and the resistance value of the second equivalent insulation resistance Rn, whether the insulation state between the positive terminal HV+ and the second reference node Ground and the insulation state between the negative terminal HV- and the second reference node Ground are abnormal is determined according to the resistance value of the first equivalent insulation resistance Rp and the resistance value of the second equivalent insulation resistance Rn.

[0139] In the embodiments of the present disclosure, if the resistance value of the first equivalent insulation resistance Rp is less than the preset insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground is insulation failure; otherwise, if the resistance value of the first equivalent insulation resistance Rp is greater than the preset insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground is insulation normal. In addition, if the resistance value of the first equivalent insulation resistance Rp is equal to the preset insulation resistance threshold, it can be determined that the insulation state between the positive terminal HV+ and the second reference node Ground is insulation failure or can be insulation normal, which is not specifically limited here.

[0140] In the embodiments of the present disclosure, if the resistance value of the second equivalent insulation resistance Rn is less than the preset insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground has insulation failure; otherwise, if the resistance value of the second equivalent insulation resistance Rn is greater than the preset insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground is normal. In addition, if the resistance value of the second equivalent insulation resistance Rn is equal to the preset insulation resistance threshold, it can be determined that the insulation state between the negative terminal HV- and the second reference node Ground has insulation failure or can be normal, which is not specifically limited here.

[0141] In the embodiments of the present disclosure, the preset insulation resistance threshold here can include a first insulation resistance threshold and a second insulation resistance threshold, and the first insulation resistance threshold is less than the second insulation resistance threshold, which is used to measure the failure degree of the insulation state. Exemplarily, if the resistance value of the first equivalent insulation resistance Rp is less than or equal to the first insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground is a first insulation failure level (for example, serious insulation failure); if the resistance value of the first equivalent insulation resistance Rp is greater than the first insulation resistance threshold and less than or equal to the second insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground is a second insulation failure level (for example, mild insulation failure). If the resistance value of the second equivalent insulation resistance Rn is less than or equal to the first insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground is the first insulation failure level (for example, serious insulation failure); if the resistance value of the second equivalent insulation resistance Rn is greater than the first insulation resistance threshold and less than or equal to the second insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground is the second insulation failure level (for example, mild insulation failure).

[0142] In some embodiments, based on the insulation detection circuit 40 shown in FIG. 4, referring to FIG. 16, the insulation detection circuit 40 can further include a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a fifth capacitor C5; wherein:

[0143] The first capacitor C1 is connected between the positive terminal HV+ and the negative terminal HV-;

[0144] The second capacitor C2 is connected between the positive terminal HV+ and the second reference node Ground;

[0145] The third capacitor C3 is connected between the negative terminal HV- and the second reference node Ground;

[0146] The fourth capacitor C4 is connected between the negative terminal HV- and the first reference node GND;

[0147] The fifth capacitor C5 is connected between the first reference node GND and the second reference node Ground.

[0148] In the embodiments of the present disclosure, the first capacitor C1 can be an X capacitor, and the second capacitor C2, the third capacitor C3, the fourth capacitor C4 and the fifth capacitor C5 can be Y capacitors. Wherein, the X capacitor and the Y capacitor both belong to the safety capacitor, the difference is that the X capacitor is connected at both ends of the input line to eliminate differential mode interference, which can suppress high frequency noise and interference; while the Y capacitor is connected between the input line and the ground line to eliminate common mode interference, which can suppress low frequency noise and protect electronic devices. Exemplarily, the fourth capacitor C4 and the fifth capacitor C5 can effectively suppress the interference of Electro-Static Discharge (ESD), Electrical Fast Transient (EFT), surge and the like from the high voltage side to the control chip.

[0149] In the embodiments of the present disclosure, as shown in the foregoing FIG. 5, the number of the first voltage dividing circuit 401 can be one or more, and each of the first voltage dividing circuit and the third voltage dividing circuit can constitute a voltage sampling circuit (or referred to as a voltage sampling channel). In this way, as the number of the first voltage dividing circuit 401 increases, the number of the voltage sampling channels herein also increases, so as to expand the multi-channel voltage sampling channel, which is beneficial to realize the demand of multi-channel voltage sampling.

[0150] It should be noted that, when calculating the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn, only the sampling voltage between the fourth resistance R4 and the ninth resistance R9 is needed to participate in the calculation, and the fourth resistance R4 and the ninth resistance R9 and the like are not needed. According to Kirchhoff's law, the parallel resistance network of the fourth resistance R4 and the ninth resistance R9 will not change the calculation result of the equivalent insulation resistance, so the embodiments of the present disclosure can arbitrarily expand the multi-channel voltage sampling channel according to the system demand.

[0151] In another specific embodiment, FIG. 17 is a detailed structure schematic diagram III of an insulation detection circuit provided by the embodiments of the present disclosure. As shown in FIG. 17, the insulation detection circuit 40 includes a fourth switch S4, an eleventh resistance R11, a twelfth resistance R12, a fourth resistance R4, a ninth resistance R9, a first switch S1, a third resistance R3, a seventh resistance R7, a thirteenth resistance R13, a second diode D2, an eighth resistance R8, a second switch S2, a first resistance R1, a second resistance R2, a sixth resistance R6, a fifth resistance R5, a first diode D1, a tenth resistance R10, a fourteenth resistance R14, a third switch S3, and a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a fifth capacitor C5.

[0152] In the embodiment of the present disclosure, the first voltage dividing circuit 401-1 includes a fourth switch S4, an eleventh resistor R11 and a twelfth resistor R12. For the first voltage dividing circuit 401-1, the first end of the fourth switch S4 is connected with the positive terminal HV+, the second end of the fourth switch S4 is connected with the first end of the eleventh resistor R11, the second end of the eleventh resistor R11 is connected with the first end of the twelfth resistor R12, the second end of the twelfth resistor R12 is connected with the first reference node GND, and the fourth sampling node V4 is led out on the connecting line between the eleventh resistor R11 and the twelfth resistor R12.

[0153] In the embodiment of the present disclosure, the first voltage dividing circuit 401-2 includes a fourth resistor R4, a ninth resistor R9 and a first switch S1. For the first voltage dividing circuit 401-2, the first end of the first switch S1 is connected with the positive terminal HV+, the second end of the first switch S1 is connected with the first end of the ninth resistor R9, the second end of the ninth resistor R9 is connected with the first end of the fourth resistor R4, the second end of the fourth resistor R4 is connected with the first reference node GND respectively, and the first sampling node V1 is led out on the connecting line between the fourth resistor R4 and the ninth resistor R9.

[0154] That is, as shown in FIG. 17, two first voltage dividing circuits (the first voltage dividing circuit 401-1 and the first voltage dividing circuit 401-2) can be included here, the first voltage dividing circuit 401-1 combined with the third voltage dividing circuit can obtain one voltage sampling circuit (the first voltage sampling channel), the first voltage dividing circuit 401-2 combined with the third voltage dividing circuit can obtain another voltage sampling circuit (the second voltage sampling channel), and the two voltage sampling channels can be used for collecting the voltage between the positive terminal HV+ and the negative terminal HV-. It should be noted that a plurality of first voltage dividing circuits such as 401-1 and 401-2 can be connected in parallel, and the plurality of first voltage dividing circuits combined with the third voltage dividing circuit can constitute a plurality of voltage sampling channels, which is beneficial to meet the demand of multi-channel voltage sampling.

[0155] In a possible implementation, as shown in FIG. 17, the first voltage sampling channel and the second voltage sampling channel can be controlled by the fourth switch S4 and the first switch S1. When the fourth switch S4 is closed, the current flows from the positive terminal HV+ to the negative terminal HV- through R11, R12, R2 / / (R1+R6), at this time, the collection voltage V4 between the first reference node GND and the positive terminal HV+ can be collected through the fourth sampling node V4, and the collection voltage V3 between the first reference node GND and the negative terminal HV- can be collected through the third sampling node V3; the first sampling high voltage U HV1 is calculated by V4 and V3.

[0156] Similarly, when the first switch S1 is closed, the current flows from the positive terminal HV+ to the negative terminal HV- through R9, R4, R2 / / (R1+R6), at this time, the acquisition voltage V1 between the first reference node GND and the positive terminal HV+ can be acquired through the first sampling node V1, and the acquisition voltage V3 between the first reference node GND and the negative terminal HV- can be acquired through the third sampling node V3; the second sampling high voltage U HV2 is calculated by V1 and V3.

[0157] Wherein, R1 represents the resistance value of the first resistor R1, R2 represents the resistance value of the second resistor R2, R4 represents the resistance value of the fourth resistor R4, R5 represents the resistance value of the fifth resistor R5, R6 represents the resistance value of the sixth resistor R6, R9 represents the resistance value of the ninth resistor R9, R 11 represents the resistance value of the eleventh resistor R11, R 12 represents the resistance value of the twelfth resistor R12, V CC represents the supply voltage of the power supply VCC.

[0158] In this way, according to the high-voltage sampling principle, the embodiment of the disclosure can expand the multi-channel voltage sampling channel according to the demand, and the calculation result of the equivalent insulation resistance will not be changed when the multi-channel voltage sampling channel is expanded.

[0159] In some embodiments, the voltage across the equivalent insulation resistance in the embodiment of the disclosure can be calibrated, thereby improving the accuracy optimization. Here, taking the voltage across the first equivalent insulation resistance Rp as an example, specifically, the positive electrode of the high-voltage source is connected with the positive terminal, the negative electrode of the high-voltage source is connected with the first reference node, the positive electrode of the high-precision multimeter is connected with the positive terminal, and the negative electrode of the high-precision multimeter is connected with the second reference node; the high-voltage source is adjusted to output in a preset voltage range, and the voltage across the first equivalent insulation resistance and the reading of the high-precision multimeter are subjected to regression analysis to calibrate the first calculation voltage U p1 or the third calculation voltage U p2 .

[0160] That is, in the embodiment of the present disclosure, the voltage across the first equivalent insulation resistance Rp is obtained by subtracting the voltage collected by the second sampling node V2 from the voltage collected by the first sampling node V1. Since the voltage collected by the first sampling node V1 and the voltage collected by the second sampling node V2 are independent of each other, the sampling errors of the two will be superimposed on the voltage Up across the first equivalent insulation resistance Rp, which will cause the insulation sampling accuracy to deteriorate. In order to overcome the influence of error superposition, Up needs to be calibrated. The specific calibration method can be: 1) connecting the positive pole of the high-voltage source to the positive terminal HV+, connecting the negative pole of the high-voltage source to the first reference node GND, connecting the positive pole of the high-precision multimeter to the positive terminal HV+, and connecting the negative pole of the high-precision multimeter to the second reference node Ground; 2) adjusting the high-voltage source to output in the range of 0V to the system voltage; 3) performing regression analysis on Up and the reading of the high-precision multimeter, thereby calibrating and correcting the voltage sampling error.

[0161] Similarly, the voltage Un across the second equivalent insulation resistance Rn can also be calibrated here, and the calibration principle is similar to the above calibration method. In addition, in order to ensure the voltage sampling accuracy, the voltage sampling value can also be calibrated according to the system requirements, thereby improving the accuracy of insulation detection.

[0162] In some embodiments, the resistance value offset of the equivalent insulation resistance can be indicated in the embodiment of the present disclosure to avoid abnormal insulation conditions. Among them, the insulation detection circuit 40 is further configured to determine that the sampling voltage at the second sampling node V2 is in a preset power supply range when the resistance value of the first equivalent insulation resistance Rp is equal to the resistance value of the second equivalent insulation resistance Rn; or, determine that the sampling voltage at the second sampling node V2 is greater than the preset power supply range when the resistance value of the first equivalent insulation resistance Rp is greater than the resistance value of the second equivalent insulation resistance Rn; or, determine that the sampling voltage at the second sampling node V2 is less than the preset power supply range when the resistance value of the first equivalent insulation resistance Rp is less than the resistance value of the second equivalent insulation resistance Rn.

[0163] In the embodiment of the present disclosure, the preset power supply range can be a preset voltage interval, for example, [preset lower limit value, preset upper limit value]. Specifically, when the sampling voltage at the second sampling node V2 is greater than the preset power supply range, the sampling voltage at the second sampling node V2 can be greater than the preset upper limit value of the preset power supply range; and when the sampling voltage at the second sampling node V2 is less than the preset power supply range, the sampling voltage at the second sampling node V2 can be less than the preset lower limit value of the preset power supply range.

[0164] In this embodiment of the disclosure, if the equivalent insulation resistance Rp = Rn, the sampling voltage at the second sampling node V2 can be within [a preset lower limit value and a preset upper limit value]; if the equivalent insulation resistance Rp is greater than Rn, the sampling voltage at the second sampling node V2 can be greater than the preset upper limit value; if the equivalent insulation resistance Rp is less than Rn, the sampling voltage at the second sampling node V2 can be less than the preset lower limit value.

[0165] For example, with 1 / 2V CC Taking the measurement range as an example, the preset lower limit value can be 1 / 2V. CC -Δ1; The upper limit of voltage can be 1 / 2V. CC +Δ2. Here, Δ1 and Δ2 can be equal or unequal. For example, Δ1 and Δ2 can be set to 100mV, 200mV, 300mV, etc., without any restrictions.

[0166] It should be noted that the power supply voltage V here is... CC This can be the supply voltage of the power supply VCC. For example, after reasonably adjusting the circuit parameters of the insulation detection circuit 40, when the equivalent insulation resistance Rp = Rn, the sampling voltage at the second sampling node V2 can be adjusted to 1 / 2V. CC When the equivalent insulation resistance Rp is greater than Rn, the sampling voltage at the second sampling node V2 will be greater than 1 / 2V. CC The range increases with the difference; when the equivalent insulation resistance Rp is less than Rn, the sampling voltage at the second sampling node V2 will be less than 1 / 2V. CC The range decreases as the difference increases. Therefore, insulation anomalies can be indicated by the sampling voltage at the second sampling node V2, enabling timely detection of faults in the insulation detection circuit.

[0167] It should also be noted that in this embodiment, whether acquiring the sampling voltage at the first sampling node V1, the second sampling node V2, the third sampling node V3, or the fourth sampling node V4, the corresponding sampling circuit uses the first reference node GND as the reference point. That is, these sampling circuits use the same reference point (i.e., the first reference node GND) for sampling, rather than using the negative terminal HV- as the reference node in related technologies. In related technologies, since there is a high voltage between the negative terminal HV- and the microcontroller's reference node GND, additional isolation components are required, leading to increased costs. However, in this embodiment, the sampling circuits all use the first reference node GND as the reference point, and there is no need for high-voltage isolation between the first reference node GND and the microcontroller's reference node GND. Therefore, these sampling circuits do not require additional isolation components, such as isolation communication chips or isolation power supplies, thereby simplifying the circuit and reducing circuit costs.

[0168] The insulation detection circuit provided by the embodiments of the present disclosure can not only sample voltage by using the first voltage dividing circuit and the third voltage dividing circuit, but also can realize insulation detection by using the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit and the fourth voltage dividing circuit, so that voltage sampling and insulation detection can be realized at the same time, the circuit structure capable of realizing multiple functional circuits is simplified, the cost is reduced, and the first calculation voltage and the second calculation voltage and the third calculation voltage and the fourth calculation voltage obtained according to the opening and closing states of the first switch, the second switch and the third switch can also be used to calculate the resistance value of the equivalent insulation resistance; in addition, when the voltage sampling channel is composed of the first voltage dividing circuit and the third voltage dividing circuit, the elements in the first voltage dividing circuit and the third voltage dividing circuit do not participate in the calculation of the equivalent insulation resistance, and the parallel connection of multiple first voltage dividing circuits does not change the resistance value of the equivalent insulation resistance. Here, multiple first voltage dividing circuits can be connected in parallel at will, so that the multiple first voltage dividing circuits and the third voltage dividing circuit can form multiple voltage sampling channels, solve the problem of inconvenient expansion of the voltage sampling channel in the related art, make the expansion of the voltage sampling channel flexible, and further improve the overall performance of the insulation detection circuit.

[0169] In another embodiment of the present disclosure, FIG. 18 is a flowchart of an insulation detection method provided by an embodiment of the present disclosure. As shown in FIG. 18, the method can include:

[0170] S1801, when the first switch is closed and the second switch and the third switch are opened, the first calculation voltage across the first equivalent insulation resistance and the second calculation voltage across the second equivalent insulation resistance are determined by the voltage collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit.

[0171] S1802, the opening and closing states of the second switch and the third switch are determined according to the first calculation voltage and the second calculation voltage, and the third calculation voltage across the first equivalent insulation resistance and the fourth calculation voltage across the second equivalent insulation resistance are determined by the voltage collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit.

[0172] S1803, the resistance values of the first equivalent insulation resistance and the second equivalent insulation resistance are determined according to the first calculation voltage and the third calculation voltage across the first equivalent insulation resistance and the second calculation voltage and the fourth calculation voltage across the second equivalent insulation resistance.

[0173] S1804, whether the insulation state between the positive terminal and the second reference node and between the negative terminal and the second reference node is abnormal is determined according to the resistance values of the first equivalent insulation resistance and the second equivalent insulation resistance.

[0174] In the embodiments of the present disclosure, the insulation detection method is applied to the insulation detection circuit 40 in the foregoing embodiments. The first switch is arranged in the first voltage dividing circuit, the second switch is arranged in the second voltage dividing circuit, and the third switch is arranged in the fourth voltage dividing circuit. The first voltage dividing circuit is connected in series between the positive terminal and the first reference node, the fourth voltage dividing circuit is connected in series between the positive terminal and the second reference node, the second voltage dividing circuit is connected in series between the second reference node and the first reference node, and the third voltage dividing circuit is connected in series between the negative terminal and the first reference node.

[0175] In the embodiments of the present disclosure, the first equivalent insulation resistance represents an equivalent resistance value between the positive terminal and the second reference node, and the second equivalent insulation resistance represents an equivalent resistance value between the negative terminal and the second reference node.

[0176] In the embodiments of the present disclosure, based on the on-off states of the first switch, the second switch and the third switch, after the first calculation voltage U p1 and the third calculation voltage U p2 across the first equivalent insulation resistance Rp and the second calculation voltage U n1 and the fourth calculation voltage U n2 across the second equivalent insulation resistance Rn are calculated according to the obtained sampling voltages, the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn can be solved according to the simultaneous equations. After the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn are determined, the insulation aging conditions between the positive terminal and the second reference node and between the negative terminal and the second reference node can be further determined.

[0177] In some embodiments, for step S1801, the first calculation voltage across the first equivalent insulation resistance and the second calculation voltage across the second equivalent insulation resistance determined by the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit can include: obtaining the first sampling voltage by the first voltage dividing circuit, obtaining the second sampling voltage by the second voltage dividing circuit, and obtaining the third sampling voltage by the third voltage dividing circuit; determining the first calculation voltage across the first equivalent insulation resistance and the second calculation voltage across the second equivalent insulation resistance according to the first sampling voltage, the second sampling voltage and the third sampling voltage.

[0178] In the embodiments of the present disclosure, the first sampling voltage is obtained by the first voltage dividing circuit, specifically the voltage collected at the first sampling node V1; the second sampling voltage is obtained by the second voltage dividing circuit, specifically the voltage collected at the second sampling node V2; and the third sampling voltage is obtained by the third voltage dividing circuit, specifically the voltage collected at the third sampling node V3.

[0179] Thus, when the first switch is closed and the second and third switches are open, the first calculated voltage U across the first equivalent insulation resistance Rp is calculated based on the first, second, and third sampled voltages, combined with the aforementioned formulas (1) and (2). p1 The second calculated voltage U across the second equivalent insulation resistance Rn n1 .

[0180] In this embodiment of the disclosure, step S1802 can be implemented in two ways. In some embodiments, referring to FIG19, step S1802 may specifically include:

[0181] S1901: When the first calculated voltage is greater than or equal to the second calculated voltage, the second switch is closed and the third switch is open.

[0182] S1902, when the first calculated voltage is less than the second calculated voltage, determine that the third switch is closed and the second switch is open.

[0183] S1903, the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance are determined by the voltages collected by the first voltage divider circuit, the second voltage divider circuit and the third voltage divider circuit.

[0184] It should be noted that the open / closed states of the second and third switches can be determined by comparing the magnitudes of the first and second calculated voltages. Specifically, when the first calculated voltage is greater than or equal to the second calculated voltage, the second switch is closed and the third switch is open; or, when the first calculated voltage is less than the second calculated voltage, the third switch is closed and the second switch is open.

[0185] In other words, by comparing the first calculated voltage U p1 Second calculated voltage U n1 The magnitude of the voltage is used to determine which of the second and third switches is closed. Then, after the circuit stabilizes, the third calculated voltage U across the first equivalent insulation resistance Rp is determined by the sampled voltages obtained from the first, second, and third voltage divider circuits. p2 The fourth calculated voltage U across the second equivalent insulation resistance Rn n2 .

[0186] For example, if U p1 ≥U n1 Then the second switch is closed. At this time, the switch states are: the first and second switches are closed, and the third switch is open. Then, the third calculated voltage U across the first equivalent insulation resistance Rp is determined based on the collected voltages obtained from the first, second, and third voltage divider circuits. p2 The fourth calculated voltage U across the second equivalent insulation resistance Rnn2 Alternatively, if U p1 <U n1 , the third switch is closed, and the switch state at this time is that the first switch and the third switch are closed, and the second switch is open, then the third calculation voltage U p2 across the first equivalent insulation resistance Rp and the fourth calculation voltage U n2 across the second equivalent insulation resistance Rn are determined according to the collected voltages obtained by the first voltage dividing circuit, the second voltage dividing circuit, and the third voltage dividing circuit.

[0187] In a possible implementation, the third calculation voltage across the first equivalent insulation resistance and the fourth calculation voltage across the second equivalent insulation resistance determined by the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit, and the third voltage dividing circuit can include: when the first switch and the second switch are closed and the third switch is open, obtaining a fourth collected voltage by the first voltage dividing circuit, obtaining a fifth collected voltage by the second voltage dividing circuit, obtaining a sixth collected voltage by the third voltage dividing circuit, and determining the third calculation voltage across the first equivalent insulation resistance and the fourth calculation voltage across the second equivalent insulation resistance according to the fourth collected voltage, the fifth collected voltage, and the sixth collected voltage.

[0188] In the embodiment of the present disclosure, if U p1 <U n1 , the first switch and the second switch are closed, and the third switch is open, in this case, the third calculation voltage U 12 across the first equivalent insulation resistance Rp and the fourth calculation voltage U 22 across the second equivalent insulation resistance Rn are calculated according to the fourth collected voltage U 32 , the fifth collected voltage U p2 , and the sixth collected voltage U n2 , and then combined with the foregoing formulas (3) and (4).

[0189] In another possible implementation, the third calculation voltage across the first equivalent insulation resistance and the fourth calculation voltage across the second equivalent insulation resistance determined by the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit, and the third voltage dividing circuit can include: when the first switch and the third switch are closed and the second switch is open, obtaining a fourth collected voltage by the first voltage dividing circuit, obtaining a fifth collected voltage by the second voltage dividing circuit, obtaining a sixth collected voltage by the third voltage dividing circuit, and determining the third calculation voltage across the first equivalent insulation resistance and the fourth calculation voltage across the second equivalent insulation resistance according to the fourth collected voltage, the fifth collected voltage, and the sixth collected voltage.

[0190] In the embodiment of the present disclosure, if U p1 <U p2Then the first switch and the third switch are closed, and the second switch is opened, in which case, according to the obtained fourth acquisition voltage U 12 , fifth acquisition voltage U 22 and sixth acquisition voltage U 32 , the third calculation voltage U p2 across the first equivalent insulation resistance Rp and the fourth calculation voltage U n2 across the second equivalent insulation resistance Rn are calculated in combination with the aforementioned formulas (3) and (4).

[0191] Further, after the first calculation voltage U p1 across the first equivalent insulation resistance Rp and the third calculation voltage U p2 across the first equivalent insulation resistance Rp are calculated, and the second calculation voltage U n1 across the second equivalent insulation resistance Rn and the fourth calculation voltage U n2 across the second equivalent insulation resistance Rn are calculated, the equivalent insulation resistance calculation formulas as shown in formulas (5) and (6) can be obtained by solving the formulas (1)~(4) simultaneously.

[0192] Thus, after the acquisition voltages under different switch states are obtained, the first calculation voltage U p1 across the first equivalent insulation resistance Rp and the second calculation voltage U n1 across the second equivalent insulation resistance Rn can be calculated according to the obtained acquisition voltages, and the third calculation voltage U p2 across the first equivalent insulation resistance Rp and the fourth calculation voltage U n2 across the second equivalent insulation resistance Rn are calculated; then the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn can be obtained in combination with formulas (5) and (6), so as to realize the calculation of the first equivalent insulation resistance and the second equivalent insulation resistance.

[0193] It can be understood that in the embodiments of the present disclosure, the number of the first voltage dividing circuits can be one or more, and each first voltage dividing circuit and the third voltage dividing circuit can constitute a voltage sampling circuit (or referred to as a voltage sampling channel). In this way, as the number of the first voltage dividing circuits 401 increases, the number of voltage sampling channels also increases, so that the multi-channel voltage sampling channels can be expanded, and the calculation result of the equivalent insulation resistance will not be changed when the multi-channel voltage sampling channels are expanded.

[0194] It can also be understood that in the embodiments of the present disclosure, the resistance deviation of the equivalent insulation resistance can be indicated to avoid the occurrence of insulation abnormality. In some embodiments, a second sampling node is arranged in the second voltage dividing circuit, specifically in the second detection unit of the second voltage dividing circuit. The method can further include: when the resistance of the first equivalent insulation resistance is equal to the resistance of the second equivalent insulation resistance, determining that the sampling voltage at the second sampling node is in the preset power supply range; or when the resistance of the first equivalent insulation resistance is greater than the resistance of the second equivalent insulation resistance, determining that the sampling voltage at the second sampling node is greater than the preset power supply range; or when the resistance of the first equivalent insulation resistance is less than the resistance of the second equivalent insulation resistance, determining that the sampling voltage at the second sampling node is less than the preset power supply range.

[0195] In the embodiments of the present disclosure, the preset power supply range can be a preset voltage interval, for example, [pre-set lower limit value, pre-set upper limit value]. When the sampling voltage at the second sampling node V2 is greater than the preset power supply range, specifically, the sampling voltage at the second sampling node V2 can be greater than the pre-set upper limit value of the preset power supply range; when the sampling voltage at the second sampling node V2 is less than the preset power supply range, specifically, the sampling voltage at the second sampling node V2 can be less than the pre-set lower limit value of the preset power supply range.

[0196] In the embodiments of the present disclosure, if the equivalent insulation resistance Rp is equal to Rn, the sampling voltage at the second sampling node V2 can be within [pre-set lower limit value, pre-set upper limit value]; if the equivalent insulation resistance Rp is greater than Rn, the sampling voltage at the second sampling node V2 can be greater than the pre-set upper limit value; if the equivalent insulation resistance Rp is less than Rn, the sampling voltage at the second sampling node V2 can be less than the pre-set lower limit value.

[0197] For example, the voltage lower limit value can be 1 / 2V CC For example, the voltage lower limit value can be 1 / 2V CC -Δ1; and the voltage upper limit value can be 1 / 2V CC +Δ2. Here, Δ1 and Δ2 can be equal or not equal. For example, Δ1 and Δ2 can be set to 100mV, 200mV, 300mV, etc., which are not limited herein.

[0198] It should be noted that the power supply voltage V CC may be the power supply voltage of the power supply VCC. For example, after reasonably adjusting the circuit parameters of the insulation detection circuit, when the equivalent insulation resistance Rp is equal to Rn, the sampling voltage at the second sampling node V2 can be adjusted to 1 / 2V CC range, when the equivalent insulation resistance Rp is greater than Rn, the sampling voltage at the second sampling node V2 will be greater than 1 / 2V CCThe sampling voltage at the second sampling node V2 is less than 1 / 2V when the equivalent insulation resistance Rp is less than Rn, and the sampling voltage at the second sampling node V2 increases with the gap CC The sampling voltage at the second sampling node V2 is less than 1 / 2V when the equivalent insulation resistance Rp is less than Rn, and the sampling voltage at the second sampling node V2 increases with the gap

[0199] It can also be understood that in the embodiments of the present disclosure, the voltage across the equivalent insulation resistance can be calibrated here to improve the accuracy and optimization. Taking the voltage across the first equivalent insulation resistance as an example, in some embodiments, the method can further include: connecting the positive pole of the high-voltage source to the positive pole terminal, connecting the negative pole of the high-voltage source to the first reference node, connecting the positive pole of the high-precision multimeter to the positive pole terminal, and connecting the negative pole of the high-precision multimeter to the second reference node; adjusting the high-voltage source to output in a preset voltage range, and performing regression analysis on the voltage across the first equivalent insulation resistance and the reading of the high-precision multimeter to calibrate the first calculated voltage or the third calculated voltage.

[0200] That is, the voltage Up across the first equivalent insulation resistance is obtained by subtracting the voltage collected by the second sampling node V2 from the voltage collected by the first sampling node V1. Since the voltage collected by the first sampling node V1 and the voltage collected by the second sampling node V2 are independent of each other, the sampling errors of the two will be superimposed on the voltage Up across the first equivalent insulation resistance, which will cause the insulation sampling accuracy to deteriorate. In order to overcome the influence of error superposition, Up needs to be calibrated, and the specific calibration method can be: 1) connecting the positive pole of the high-voltage source to the positive pole terminal HV+, connecting the negative pole of the high-voltage source to the first reference node GND, connecting the positive pole of the high-precision multimeter to the positive pole terminal HV+, and connecting the negative pole of the high-precision multimeter to the second reference node Ground; 2) adjusting the high-voltage source to output in the range of 0V to the system voltage; 3) performing regression analysis on Up and the reading of the high-precision multimeter to calibrate and correct the voltage sampling error.

[0201] Similarly, the voltage Un across the second equivalent insulation resistance can also be calibrated here, and the calibration principle is similar to the above calibration method. In addition, in order to guarantee the voltage sampling accuracy, the voltage sampling value can also be calibrated according to the system requirements, so as to improve the accuracy of insulation detection.

[0202] It can also be understood that in the embodiments of the present disclosure, after obtaining the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn, it is determined whether the insulation state between the positive pole terminal HV+ and the second reference node Ground and between the negative pole terminal HV- and the second reference node Ground is abnormal according to the resistance values of the first equivalent insulation resistance Rp and the second equivalent insulation resistance Rn.

[0203] In some embodiments, for step S1804, the method can comprise: determining that the insulation state between the positive terminal and the second reference node has insulation failure when the resistance value of the first equivalent insulation resistance is less than the preset insulation resistance threshold; and determining that the insulation state between the positive terminal and the second reference node is normal when the resistance value of the first equivalent insulation resistance is greater than the preset insulation resistance threshold.

[0204] In the embodiments of the present disclosure, if the resistance value of the first equivalent insulation resistance Rp is less than the preset insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground has insulation failure; otherwise, if the resistance value of the first equivalent insulation resistance Rp is greater than the preset insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground is normal. In addition, if the resistance value of the first equivalent insulation resistance Rp is equal to the preset insulation resistance threshold, it can be determined that the insulation state between the positive terminal HV+ and the second reference node Ground has insulation failure or can be normal, which is not specifically limited here.

[0205] It should be further noted that in the embodiments of the present disclosure, the preset insulation resistance threshold herein can comprise a first insulation resistance threshold and a second insulation resistance threshold, and the first insulation resistance threshold is less than the second insulation resistance threshold, for measuring the failure degree of the insulation state. Illustratively, if the resistance value of the first equivalent insulation resistance Rp is less than or equal to the first insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground is the first insulation failure level (for example, serious insulation failure); if the resistance value of the first equivalent insulation resistance Rp is greater than the first insulation resistance threshold and less than or equal to the second insulation resistance threshold, it is determined that the insulation state between the positive terminal HV+ and the second reference node Ground is the second insulation failure level (for example, mild insulation failure).

[0206] In some embodiments, for step S1804, the method can further comprise: determining that the insulation state between the negative terminal and the second reference node has insulation failure when the resistance value of the second equivalent insulation resistance is less than the preset insulation resistance threshold; and determining that the insulation state between the negative terminal and the second reference node is normal when the resistance value of the second equivalent insulation resistance is greater than the preset insulation resistance threshold.

[0207] In the embodiments of the present disclosure, if the resistance value of the second equivalent insulation resistance Rn is less than the preset insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground has insulation failure; otherwise, if the resistance value of the second equivalent insulation resistance Rn is greater than the preset insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground is normal. In addition, if the resistance value of the second equivalent insulation resistance Rn is equal to the preset insulation resistance threshold, it can be determined that the insulation state between the negative terminal HV- and the second reference node Ground has insulation failure or can be normal, which is not specifically limited here.

[0208] It should be further pointed out that in the embodiments of the present disclosure, the preset insulation resistance threshold here can include a first insulation resistance threshold and a second insulation resistance threshold, and the first insulation resistance threshold is less than the second insulation resistance threshold, which is used to measure the failure degree of the insulation state. Exemplarily, if the resistance value of the second equivalent insulation resistance Rn is less than or equal to the first insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground is in a first insulation failure level (for example, serious insulation failure); if the resistance value of the second equivalent insulation resistance Rn is greater than the first insulation resistance threshold and less than or equal to the second insulation resistance threshold, it is determined that the insulation state between the negative terminal HV- and the second reference node Ground is in a second insulation failure level (for example, mild insulation failure).

[0209] The embodiments of the present disclosure provide an insulation detection method, in particular an insulation detection method applied to a high-voltage insulation detection circuit. Based on the opening and closing states of the first switch, the second switch and the third switch, the first calculation voltage across the first equivalent insulation resistance and the second calculation voltage across the second equivalent insulation resistance, and the third calculation voltage across the first equivalent insulation resistance and the fourth calculation voltage across the second equivalent insulation resistance can be determined through the voltages collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit, so as to calculate the resistance value of the equivalent insulation resistance, and through the calibration of the voltage sampling value, the precision of the insulation detection can be improved; in addition, the insulation detection circuit not only can use the first voltage dividing circuit and the third voltage dividing circuit for voltage sampling, but also can use the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit and the fourth voltage dividing circuit to realize insulation detection, so that high-voltage sampling and insulation detection can be realized at the same time, the circuit structure is simplified, and the circuit cost is reduced; and when the first voltage dividing circuit and the third voltage dividing circuit are used to form a voltage sampling channel, the elements in the first voltage dividing circuit and the third voltage dividing circuit do not participate in the calculation of the equivalent insulation resistance, so that by arbitrarily expanding multiple first voltage dividing circuits, the multiple first voltage dividing circuits and the third voltage dividing circuit can form many voltage sampling channels, solving the problem of inconvenient expansion of voltage sampling channels in the related art, and making the expansion of voltage sampling channels flexible.

[0210] In yet another embodiment of the present disclosure, based on the insulation detection circuit 40 of the foregoing embodiment, the positive terminal HV+ is the positive pole of the battery voltage, the negative terminal HV- is the negative pole of the battery voltage, the first reference node GND is the low-voltage ground (connected to the negative pole of the low-voltage power supply DC-DC circuit, and the negative pole of the DC-DC circuit and the ground of the control chip (for example, MCU) are the same connection); the second reference node Ground is the earth, which is usually connected to the device shell, that is, the metal that can be touched by people; Rp and Rn are the equivalent insulation resistances of HV+ to Ground and HV- to Ground, respectively, and the resistance values are used to characterize the insulation aging condition of the BMS; in addition, C1 is the equivalent X capacitor, C2, C3, C4 and C5 are the common Y capacitors, and C4 and C5 can effectively suppress the interference of ESD, EFT, surge and the like from the high-voltage return to the control chip such as the single-chip microcomputer and MCU.

[0211] In some embodiments, the insulation detection circuit adopts a segmented voltage sampling circuit. Taking two voltage sampling channels as an example, the first voltage sampling channel and the second voltage sampling channel can be controlled by the fourth switch S4 and the first switch S1.

[0212] When the fourth switch S4 is closed, the current flows from HV+ to HV- through R11, R12, R2 / / (R1+R6), at this time, the acquisition voltage V4 between GND and HV+ can be collected through the fourth sampling node V4, and the acquisition voltage V3 between GND and HV- can be collected through the third sampling node V3; by V4 and V3, the first sampling high voltage U HV1 .

[0213] Similarly, when the first switch S1 is closed, the current flows from HV+ to HV- through R9, R4, R2 / / (R1+R6), at this time, the acquisition voltage V1 between GND and HV+ can be collected through the first sampling node V1, and the acquisition voltage V3 between GND and HV- can be collected through the third sampling node V3; by V1 and V3, the second sampling high voltage U HV2 .

[0214] According to the high-voltage sampling principle, the technical solution can expand multiple voltage sampling channels according to the needs.

[0215] In some embodiments, for the insulation detection circuit, R10 / / R14, R8 / / (R7+R3) and R2 / / (R1+R6) constitute the insulation detection circuit. Among them, the voltage V1 can be collected through the first sampling node V1, the voltage V2 can be collected through the second sampling node V2, and the voltage V3 can be collected through the third sampling node V3, and the voltage Up1 V1-V2, the voltage U across Rn n1 V2+V3; by closing S3 or S4, the voltage across Rp and Rn can be changed, and then the circuit equation groups before and after closing are solved to obtain the resistance value of the first equivalent insulation resistance Rp and the resistance value of the second equivalent insulation resistance Rn.

[0216] In a specific embodiment, for the insulation detection circuit, the insulation detection method comprises:

[0217] Step 1, after the system is powered on, the first switch S1 is closed, and after the circuit voltage is stabilized, the voltage U collected by the first sampling node V1, the voltage U collected by the second sampling node V2, and the voltage U collected by the third sampling node V3 are obtained. 11 21 21 Then, according to U 11 , U 21 , and U 31 , the first calculation voltage U p1 across the first equivalent insulation resistance Rp and the second calculation voltage U n1 across the second equivalent insulation resistance Rn are calculated in combination with the aforementioned formulas (1) and (2).

[0218] Step 2, the sizes of U p1 and U n1 are compared, if U p1 ≥ U n1 , the second switch S2 is closed, and after the circuit voltage is stabilized, the voltage U collected by the first sampling node V1, the voltage U collected by the second sampling node V2, and the voltage U collected by the third sampling node V3 are obtained. 12 22 32 Then, according to U 12 , U 22 , and U 32 , the third calculation voltage U p2 across the first equivalent insulation resistance Rp and the fourth calculation voltage U n2 across the second equivalent insulation resistance Rn are calculated in combination with the aforementioned formulas (3) and (4).

[0219] Step 3, the resistance value of the first equivalent insulation resistance Rp and the resistance value of the second equivalent insulation resistance Rn are calculated. Specifically, the Kirchhoff equation is solved with the second reference node Ground node, specifically, the formulas (1)-(4) are solved, and finally the resistance values of the equivalent insulation resistances Rp and Rn are calculated according to the aforementioned formulas (5) and (6).

[0220] Or, if U p1 <U n1 ​​​​, then the third switch S3 is closed, and after the circuit voltage is stabilized, the voltage U collected by the first sampling node V1 is obtained 12 , the voltage U collected by the second sampling node V2 is obtained 22 , and the voltage U collected by the third sampling node V3 is obtained 32 The third calculation voltage U across the first equivalent insulation resistance Rp and the fourth calculation voltage U across the second equivalent insulation resistance Rn are calculated by the foregoing formulas (3) and (4) p2 n2 ; similarly, the resistance values of the equivalent insulation resistances Rp and Rn can also be calculated.

[0221] In some embodiments, for the insulation detection circuit, the voltage sampling channel is expanded, that is, according to the calculation formulas (1)-(6), when the equivalent insulation resistances Rp and Rn are calculated, only the sampling voltage across R4 and R9 needs to be obtained for calculation, and resistors such as R11, R12, R4, and R9 do not need to be involved. According to Kirchhoff's law, the parallel resistor network of R4 and R9 will not change the calculation parameters of the insulation detection, and therefore, the embodiments of the present disclosure can arbitrarily expand the multi-channel voltage sampling channel according to system requirements.

[0222] In some embodiments, for precision optimization, the voltage across Rp is obtained by subtracting the voltage collected by the second sampling node V2 from the voltage collected by the first sampling node V1. Since the voltage collected by the first sampling node V1 and the voltage collected by the second sampling node V2 are independent of each other, the sampling errors of the two will be superimposed on the voltage Up across Rp, which will cause the insulation sampling precision to deteriorate. In order to overcome the influence of error superposition, Up needs to be calibrated, and the specific calibration method can be as follows: 1) connecting the positive pole of the high-voltage source to the positive terminal HV+, connecting the negative pole of the high-voltage source to the first reference node GND, connecting the positive pole of the high-precision multimeter to the positive terminal HV+, and connecting the negative pole of the high-precision multimeter to the second reference node Ground; 2) adjusting the high-voltage source to output in the range of 0V to the system voltage; 3) performing regression analysis on Up and the reading of the high-precision multimeter, thereby calibrating and correcting the voltage sampling error.

[0223] Similarly, the voltage Un across Rn can also be calibrated here, and the calibration principle is similar to the above calibration method. In addition, in order to guarantee the voltage sampling precision, the voltage sampling value can also be calibrated according to system requirements, thereby improving the precision of the insulation detection.

[0224] Exemplarily, for the resistance value offset indication, according to theoretical analysis and simulation display, after reasonable adjustment of the circuit parameters, when Rp = Rn, the sampling voltage at the second sampling node V2 can be adjusted to 1 / 2V CC range, and when Rp is greater than Rn, the sampling voltage at the second sampling node V2 will be greater than 1 / 2V​CC the sampling voltage at the second sampling node V2 is less than 1 / 2V CC the sampling voltage at the second sampling node V2 is less than 1 / 2V

[0225] It should be further noted that, in the embodiments of the present disclosure, whether the sampling voltage at the first sampling node V1 or the second sampling node V2, the third sampling node V3 or the fourth sampling node V4 is acquired, the first reference node GND is used as the reference point in the corresponding sampling circuit, that is, the same reference point (i.e., the first reference node GND) is used for sampling in these sampling circuits, rather than the negative terminal HV- as the reference node in the related art. For the related art, because there is a high voltage between the negative terminal HV- and the reference node GND of the microcontroller, an additional isolation component needs to be added, resulting in an increase in cost. However, in the embodiments of the present disclosure, the sampling circuit uses the first reference node GND as the reference point, and the first reference node GND and the reference node GND of the microcontroller do not need to be high-voltage isolated, so that the sampling circuit does not need to add an additional isolation component, such as an isolation communication chip, an isolation power supply, and the like, thereby achieving the purpose of simplifying the circuit and reducing the cost of the circuit.

[0226] In still another embodiment of the present disclosure, FIG. 20 is a schematic diagram of the composition structure of a battery management system provided by the embodiment of the present disclosure. As shown in FIG. 20, the battery management system 200 can include a control circuit 2001 and the insulation detection circuit 40 as in the foregoing embodiments.

[0227] In the embodiments of the present disclosure, the control circuit 2001 is configured to provide a switching control signal to the insulation detection circuit 40 to control the opening and closing states of the first switch S1, the second switch S2 and the third switch S3.

[0228] In the embodiments of the present disclosure, the control circuit 2001 can be integrated in a control chip, such as a single-chip microcomputer, an MCU, and the like.

[0229] In this way, for the battery management system 200, based on the on-off state of the first switch S1, the second switch S2 and the third switch S3, the insulation detection circuit 40 can use the voltage collected by the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit to calculate the first calculation voltage and the third calculation voltage across the first equivalent insulation resistance and the second calculation voltage and the fourth calculation voltage across the second equivalent insulation resistance, and further calculate the resistance value of the first equivalent insulation resistance Rp and the resistance value of the second equivalent insulation resistance Rn, so as to realize the calculation of the equivalent insulation resistance, and further determine whether the insulation state between the positive terminal and the second reference node and the insulation state between the negative terminal and the second reference node are abnormal.

[0230] In still another embodiment of the present disclosure, FIG. 21 is a schematic diagram of a composition structure of a battery pack provided by an embodiment of the present disclosure. As shown in FIG. 21, the battery pack 210 can include a battery 2101 and the battery management system 200 as in the foregoing embodiments.

[0231] In an embodiment of the present disclosure, the positive terminal of the battery 2101 is connected to the positive terminal HV+ of the insulation detection circuit 40 in the battery management system 200, and the negative terminal of the battery 2101 is connected to the negative terminal HV- of the insulation detection circuit 40 in the battery management system 200. Wherein, the battery pack 210 can be used as a power battery to provide a direct current high voltage output to the insulation detection circuit 40.

[0232] In an embodiment of the present disclosure, the present disclosure further provides a vehicle, which can include a battery, a vehicle controller and a battery management system as in the foregoing embodiments. Wherein, the vehicle controller is connected to the control circuit in the battery management system to realize information interaction between the vehicle controller and the battery management system.

[0233] In still another embodiment of the present disclosure, the present disclosure provides a computer readable storage medium having stored thereon a computer program, which when executed implements the insulation detection method of any one of the foregoing embodiments.

[0234] In still another embodiment of the present disclosure, the present disclosure further provides a computer program product including a computer program or instructions, which when executed implements the insulation detection method as in any one of the foregoing embodiments.

[0235] It should be understood that those skilled in the art will appreciate that the present disclosure can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Moreover, the present disclosure can take the form of a computer program product embodied on one or more computer-usable storage media having computer-usable program code embodied thereon, including but not limited to magnetic and optical storage media.

[0236] It should also be understood that, throughout the specification, any reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Therefore, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification are not necessarily referring to the same embodiment. Further, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that the sequence of steps / operations in the various embodiments of the disclosure is not meant to imply a fixed order of execution, with the steps / operations being executed in an order dictated by their function and internal logic, rather than according to any implementation-dependent sequence. The sequence of the above-described embodiments of the disclosure is only for description, and does not represent the advantages and disadvantages of the embodiments.

[0237] It should be noted that, in the disclosure, the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0238] In several embodiments provided by the disclosure, it should be understood that the disclosed system, device and method can be implemented in other ways. The above-described device embodiments are only illustrative, for example, the division of units is only a logical function division, and actual implementation can have another division manner, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed components can be through some interface, indirect coupling or communication connection between devices or units, which can be electrical, mechanical or other forms.

[0239] The units described above as separate components can or can not be physically separate, and the components shown as units can or can not be physical units; they can be located in one place or distributed on multiple network units; some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment. In addition, each functional unit in each embodiment of the disclosure can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be realized in the form of hardware or hardware plus software functional unit.

[0240] The above merely describes the preferred embodiments of the present disclosure, and is not used to limit the protection scope of the present disclosure, and any modification, equivalent replacement and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

An insulation detection circuit includes a first voltage divider circuit, a second voltage divider circuit, a third voltage divider circuit, and a fourth voltage divider circuit, wherein: The first voltage divider circuit is provided with a first switch, the second voltage divider circuit is provided with a second switch, and the fourth voltage divider circuit is provided with a third switch. The first voltage divider circuit is connected in series between the positive terminal and the first reference node, the fourth voltage divider circuit is connected in series between the positive terminal and the second reference node, the second voltage divider circuit is connected in series between the second reference node and the first reference node, and the third voltage divider circuit is connected in series between the negative terminal and the first reference node. The insulation detection circuit is used to determine the resistance values ​​of the first equivalent insulation resistance and the second equivalent insulation resistance based on the open / closed states of the first switch, the second switch, and the third switch, by means of the voltages collected by the first voltage divider circuit, the second voltage divider circuit, and the third voltage divider circuit; and to determine whether the insulation state between the positive terminal and the second reference node and between the negative terminal and the second reference node is abnormal based on the resistance values ​​of the first equivalent insulation resistance and the second equivalent insulation resistance. Wherein, the first equivalent insulation resistance characterizes the equivalent resistance value between the positive terminal and the second reference node, and the second equivalent insulation resistance characterizes the equivalent resistance value between the negative terminal and the second reference node. According to the insulation detection circuit of claim 1, wherein, The insulation detection circuit is used to obtain a first sampling voltage through the first voltage divider circuit, a second sampling voltage through the second voltage divider circuit, and a third sampling voltage through the third voltage divider circuit when the first switch is closed and the second switch and the third switch are open, and to determine a first calculated voltage across the first equivalent insulation resistance and a second calculated voltage across the second equivalent insulation resistance based on the first sampling voltage, the second sampling voltage and the third sampling voltage. The insulation detection circuit is further configured to determine the opening and closing states of the second switch and the third switch based on the first calculated voltage and the second calculated voltage, obtain a fourth sampling voltage through the first voltage divider circuit, obtain a fifth sampling voltage through the second voltage divider circuit, obtain a sixth sampling voltage through the third voltage divider circuit, and determine the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance based on the fourth sampling voltage, the fifth sampling voltage, and the sixth sampling voltage. The insulation detection circuit is further configured to determine the resistance value of the first equivalent insulation resistance and the resistance value of the second equivalent insulation resistance based on the first calculated voltage and the third calculated voltage across the first equivalent insulation resistance and the second calculated voltage and the fourth calculated voltage across the second equivalent insulation resistance. According to the insulation detection circuit of claim 2, wherein, The insulation detection circuit is further configured to determine that the second switch is closed and the third switch is open when the first calculated voltage is greater than or equal to the second calculated voltage; or, to determine that the third switch is closed and the second switch is open when the first calculated voltage is less than the second calculated voltage. According to the insulation detection circuit of claim 2, wherein, The first voltage divider circuit includes a first voltage divider unit and a first switch, and the third voltage divider circuit includes a second voltage divider unit and a first detection unit; The first terminal of the first switch is connected to the positive terminal, the second terminal of the first switch is connected to the first terminal of the first voltage divider unit, the second terminal of the first voltage divider unit is connected to the first reference node and the first terminal of the second voltage divider unit respectively, and the first voltage divider unit is provided with a first sampling node for acquiring the first sampling voltage or the fourth sampling voltage. The second end of the second voltage divider unit is connected to the negative terminal, and the third end of the second voltage divider unit is connected to the first detection unit. The first detection unit is provided with a third sampling node for acquiring the third sampling voltage or the sixth sampling voltage. According to the insulation detection circuit of claim 4, wherein, The second voltage divider circuit includes a third voltage divider unit, a second detection unit, a fourth voltage divider unit, and a second switch; the fourth voltage divider circuit includes a fifth voltage divider unit, a sixth voltage divider unit, and the third switch. The positive terminal is connected to the first terminal of the fifth voltage divider unit and the first terminal of the sixth voltage divider unit, respectively, and the second terminal of the sixth voltage divider unit is connected to the first terminal of the third switch; The second reference node is connected to the second end of the fifth voltage divider unit, the second end of the third switch, the first end of the third voltage divider unit, and the first end of the fourth voltage divider unit. The second end of the fourth voltage divider unit is connected to the first end of the second switch. The second end of the third voltage divider unit is connected to the second end of the second switch and the first reference node. The third end of the third voltage divider unit is connected to the second detection unit. The second detection unit is provided with a second sampling node for acquiring the second acquisition voltage or the fifth acquisition voltage. According to the insulation detection circuit of claim 5, wherein, The insulation detection circuit is further configured to determine that the sampling voltage at the second sampling node is within a preset power supply range when the resistance values ​​of the first equivalent insulation resistance and the second equivalent insulation resistance are equal; or, when the resistance value of the first equivalent insulation resistance is greater than the resistance value of the second equivalent insulation resistance, determine that the sampling voltage at the second sampling node is greater than the preset power supply range; or, when the resistance value of the first equivalent insulation resistance is less than the resistance value of the second equivalent insulation resistance, determine that the sampling voltage at the second sampling node is less than the preset power supply range. The insulation detection circuit according to any one of claims 1 to 6, wherein, The insulation detection circuit also includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor; The first capacitor is connected between the positive terminal and the negative terminal; The second capacitor is connected between the positive terminal and the second reference node; The third capacitor is connected between the negative terminal and the second reference node; The fourth capacitor is connected between the negative terminal and the first reference node; The fifth capacitor is connected between the first reference node and the second reference node. The insulation detection circuit according to any one of claims 1 to 7, wherein, The number of the first voltage divider circuits is one or more; wherein each of the first voltage divider circuits and the third voltage divider circuits respectively forms a voltage sampling circuit. An insulation detection method is applied to an insulation detection circuit, the insulation detection circuit including a first voltage divider circuit, a second voltage divider circuit, a third voltage divider circuit, and a fourth voltage divider circuit; the first voltage divider circuit includes a first switch, the second voltage divider circuit includes a second switch, and the fourth voltage divider circuit includes a third switch; the first voltage divider circuit is connected in series between the positive terminal and a first reference node, the fourth voltage divider circuit is connected in series between the positive terminal and a second reference node, the second voltage divider circuit is connected in series between the second reference node and the first reference node, and the third voltage divider circuit is connected in series between the negative terminal and the first reference node; the method includes: When the first switch is closed and the second and third switches are open, the first calculated voltage across the first equivalent insulation resistance and the second calculated voltage across the second equivalent insulation resistance are determined by the voltages collected by the first voltage divider circuit, the second voltage divider circuit and the third voltage divider circuit. The opening and closing states of the second switch and the third switch are determined based on the first calculated voltage and the second calculated voltage. The third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance are determined by the voltages collected by the first voltage divider circuit, the second voltage divider circuit and the third voltage divider circuit. The resistance values ​​of the first equivalent insulation resistance and the second equivalent insulation resistance are determined based on the first calculated voltage and the third calculated voltage across the first equivalent insulation resistance, and the second calculated voltage and the fourth calculated voltage across the second equivalent insulation resistance. Based on the resistance values ​​of the first equivalent insulation resistance and the second equivalent insulation resistance, determine whether the insulation state between the positive terminal and the second reference node and between the negative terminal and the second reference node is abnormal. Wherein, the first equivalent insulation resistance characterizes the equivalent resistance value between the positive terminal and the second reference node, and the second equivalent insulation resistance characterizes the equivalent resistance value between the negative terminal and the second reference node. The method according to claim 9, wherein, The determination of the first calculated voltage across the first equivalent insulation resistance and the second calculated voltage across the second equivalent insulation resistance using the voltages acquired by the first voltage divider circuit, the second voltage divider circuit, and the third voltage divider circuit includes: A first sampling voltage is obtained through the first voltage divider circuit, a second sampling voltage is obtained through the second voltage divider circuit, and a third sampling voltage is obtained through the third voltage divider circuit. Based on the first acquisition voltage, the second acquisition voltage, and the third acquisition voltage, determine the first calculated voltage across the first equivalent insulation resistance and the second calculated voltage across the second equivalent insulation resistance. The method according to claim 9, wherein, Determining the open / closed states of the second switch and the third switch based on the first calculated voltage and the second calculated voltage includes: When the first calculated voltage is greater than or equal to the second calculated voltage, the second switch is determined to be closed, and the third switch is determined to be open; or... When the first calculated voltage is less than the second calculated voltage, it is determined that the third switch is closed and the second switch is open. The method according to claim 11, wherein, The step of determining the third calculated voltage across the first equivalent insulation resistance and the fourth calculated voltage across the second equivalent insulation resistance using the voltages acquired by the first voltage divider circuit, the second voltage divider circuit, and the third voltage divider circuit includes: When the first switch and the second switch are closed, and the third switch is open, a fourth sampling voltage is obtained through the first voltage divider circuit, a fifth sampling voltage is obtained through the second voltage divider circuit, and a sixth sampling voltage is obtained through the third voltage divider circuit. Based on the fourth sampling voltage, the fifth sampling voltage, and the sixth sampling voltage, a third calculated voltage across the first equivalent insulation resistance and a fourth calculated voltage across the second equivalent insulation resistance are determined; or... When the first switch and the third switch are closed and the second switch is open, a fourth sampling voltage is obtained through the first voltage divider circuit, a fifth sampling voltage is obtained through the second voltage divider circuit, and a sixth sampling voltage is obtained through the third voltage divider circuit. Based on the fourth sampling voltage, the fifth sampling voltage, and the sixth sampling voltage, a third calculated voltage across the first equivalent insulation resistance and a fourth calculated voltage across the second equivalent insulation resistance are determined. The method according to any one of claims 9 to 12, wherein, A second sampling node is provided in the second voltage divider circuit; the method further includes: When the resistance values ​​of the first equivalent insulation resistance and the second equivalent insulation resistance are equal, the sampling voltage at the second sampling node is determined to be within a preset power supply range; or, When the resistance of the first equivalent insulation resistance is greater than the resistance of the second equivalent insulation resistance, the sampling voltage at the second sampling node is determined to be greater than the preset power supply range; or, When the resistance of the first equivalent insulation resistance is less than the resistance of the second equivalent insulation resistance, it is determined that the sampling voltage at the second sampling node is less than the preset power supply range. The method according to any one of claims 9 to 13, wherein, The method further includes: Connect the positive terminal of the high-voltage source to the positive terminal, connect the negative terminal of the high-voltage source to the first reference node, connect the positive terminal of the high-precision multimeter to the positive terminal, and connect the negative terminal of the high-precision multimeter to the second reference node. Adjust the high voltage source to output within a preset voltage range, and perform regression analysis on the voltage across the first equivalent insulation resistance and the reading of the high-precision multimeter to calibrate the first calculated voltage or the third calculated voltage. The method according to any one of claims 9 to 14, wherein, The step of determining whether the insulation state between the positive terminal and the second reference node and between the negative terminal and the second reference node is abnormal based on the resistance values ​​of the first and second equivalent insulation resistances includes: When the resistance value of the first equivalent insulation resistance is less than the preset insulation resistance threshold, it is determined that there is an insulation failure in the insulation state between the positive terminal and the second reference node. When the resistance value of the first equivalent insulation resistance is greater than a preset insulation resistance threshold, the insulation state between the positive terminal and the second reference node is determined to be normal; and When the resistance value of the second equivalent insulation resistance is less than the preset insulation resistance threshold, it is determined that there is an insulation failure in the insulation state between the negative terminal and the second reference node. When the resistance value of the second equivalent insulation resistance is greater than the preset insulation resistance threshold, the insulation state between the negative terminal and the second reference node is determined to be normal. The method according to any one of claims 9 to 15, wherein, The number of the first voltage divider circuits is one or more; wherein each of the first voltage divider circuits and the third voltage divider circuits respectively forms a voltage sampling circuit. A battery management system, comprising a control circuit and an insulation detection circuit as described in any one of claims 1 to 8; wherein, The control circuit is used to provide a switch control signal to the insulation detection circuit to control the opening and closing states of the first switch, the second switch and the third switch.

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