Detection circuit, battery management system and electric drive device

Abstract

The utility model discloses a kind of detection circuit, battery management system and electric drive equipment, detection circuit includes relay module, first voltage division module, second voltage division module, charge-discharge module;Among them: detection circuit, for in the case where relay module is in disconnected state and first voltage division module and second voltage division module are in different state, obtain at least one first sampling signal provided by first voltage division module, at least one second sampling signal provided by second voltage division module and at least one third sampling signal provided by charge-discharge module;Wherein, at least one first sampling signal, at least one second sampling signal and at least one third sampling signal are used to determine the resistance value of positive ground insulation resistance and the resistance value of negative ground insulation resistance.Such, can improve the sampling accuracy and reliability of insulation resistance.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a detection circuit, a battery management system, and an electric drive device. Background Technology

[0002] Insulation sampling by the Battery Management System (BMS) is a crucial step in ensuring the safe operation of the battery system. During the operation of the battery system, the BMS determines whether the insulation state of the battery system has deteriorated by measuring whether the resistance value of the insulation resistance changes.

[0003] Currently, during the insulation sampling process of BMS, due to the presence of charging and discharging components such as parasitic capacitance between the high-voltage bus of the battery pack and the vehicle body, the transient voltage change when the relay is disconnected causes fluctuations in the sampled voltage value, resulting in deviations in the measured insulation resistance value. Utility Model Content

[0004] This utility model mainly provides a detection circuit, a battery management system, and an electric drive device, which can improve the sampling accuracy and reliability of insulation resistance.

[0005] The technical solution of this utility model is implemented as follows:

[0006] In a first aspect, this utility model embodiment provides a detection circuit, which includes a relay module, a first voltage divider module, a second voltage divider module, and a charge / discharge module; wherein:

[0007] The battery insulation resistor is connected to the first voltage divider module, the second voltage divider module and the battery pack respectively; the relay module is connected between the first voltage divider module and / or the second voltage divider module and the vehicle insulation resistor; and the charging and discharging module is connected to the vehicle insulation resistor.

[0008] The detection circuit is used to acquire at least one first sampling signal provided by the first voltage divider module, at least one second sampling signal provided by the second voltage divider module, and at least one third sampling signal provided by the charging and discharging module when the relay module is in the off state and the first voltage divider module and the second voltage divider module are in different states.

[0009] Among them, at least one first sampling signal, at least one second sampling signal, and at least one third sampling signal are used to determine the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance.

[0010] Through the above technical means, the first voltage divider module and the second voltage divider module are connected between the battery insulation resistance and the vehicle insulation resistance, and the charging and discharging module is connected to the outside of the relay module. When the relay module is in the open state and the first voltage divider module and the second voltage divider module are in different states, the first sampling signal, the second sampling signal, and the third sampling signal generated by the voltage provided by the battery pack and the voltage provided by the charging and discharging module at the first voltage divider module, the second voltage divider module, and the charging and discharging module in the detection circuit are obtained respectively. In this way, the influence of the voltage change provided by the charging and discharging module outside the relay module on the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance are taken into account, thereby improving the sampling accuracy and reliability of the insulation resistance.

[0011] In some embodiments, the battery insulation resistance includes the positive-to-ground battery insulation resistance and the negative-to-ground battery insulation resistance; wherein:

[0012] The first end of the positive-to-ground battery insulation resistor is connected to the positive terminal of the battery pack and the first end of the first voltage divider module, respectively. The second end of the positive-to-ground battery insulation resistor is connected to the second end of the first voltage divider module, the first end of the second voltage divider module, and the first end of the negative-to-ground battery insulation resistor, respectively.

[0013] The second terminal of the negative-to-ground battery insulation resistor is connected to the negative terminal of the battery pack and the second terminal of the second voltage divider module, respectively.

[0014] Through the above technical means, the battery insulation resistance includes a positive-to-ground battery insulation resistance and a negative-to-ground battery insulation resistance. The positive-to-ground battery insulation resistance is connected in parallel with the first voltage divider module, and the negative-to-ground battery insulation resistance is connected in parallel with the second voltage divider module. This makes the first sampling voltage obtained by the first voltage divider module the voltage across the positive-to-ground battery insulation resistance, and the second sampling voltage obtained by the second voltage divider module the voltage across the negative-to-ground battery insulation resistance. This makes it easier to determine the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance.

[0015] In some embodiments, the relay module includes a main positive relay; wherein:

[0016] The main positive relay is connected between the first voltage divider module and the vehicle insulation resistor.

[0017] By employing the aforementioned technical means, it was determined that for a detection circuit including a main positive relay, the voltage discharged by the charging and discharging module affects the measured resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance when the main positive relay is disconnected. Based on the specific circuit structure, the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are determined, thereby improving the accuracy and reliability of insulation resistance detection.

[0018] In some embodiments, the vehicle insulation resistance includes the vehicle insulation resistance to ground and the vehicle insulation resistance to ground; wherein:

[0019] The first end of the vehicle insulation resistor that is positively grounded is connected to the first end of the main positive relay and the first end of the charging / discharging module, respectively; the second end of the vehicle insulation resistor that is positively grounded is connected to the first end of the vehicle insulation resistor that is negatively grounded and the ground end, respectively.

[0020] The second terminal of the negative-to-ground vehicle insulation resistance is connected to the second terminal of the second voltage divider module and the second terminal of the charge / discharge module, respectively.

[0021] Using the aforementioned technical methods, the vehicle insulation resistance includes both the positive-to-ground vehicle insulation resistance and the negative-to-ground vehicle insulation resistance. Based on the parallel connection of the positive-to-ground vehicle insulation resistance and the positive-to-ground battery insulation resistance, the positive-to-ground insulation resistance is determined; similarly, based on the parallel connection of the negative-to-ground vehicle insulation resistance and the negative-to-ground battery insulation resistance, the negative-to-ground insulation resistance is determined. This allows for accurate determination of the resistance values ​​of both positive and negative ground insulation resistance, thereby improving the accuracy and reliability of insulation resistance detection.

[0022] In some embodiments, the first voltage divider module includes a first resistor, a second resistor, a third resistor, and a first switch; wherein:

[0023] The first end of the first resistor is connected to the first end of the insulation resistor of the battery facing ground and the first end of the second resistor respectively, and the second end of the first resistor is connected to the first end of the first switch.

[0024] The first end of the second resistor is connected to the main positive relay, and the second end of the second resistor is connected to the first end of the third resistor.

[0025] The second terminal of the first switch is connected to the second terminal of the third resistor, the second terminal of the battery insulation resistor facing ground, and the second voltage divider module, respectively.

[0026] The second end of the third resistor is also connected to the second end of the vehicle insulation resistor facing the ground and the ground end, respectively.

[0027] The sampling point between the second resistor and the third resistor is used to acquire the first sampling signal.

[0028] By employing the aforementioned technical means, when the main positive relay is in the off state and the first switch is in different states, the connection method between the first voltage divider module and the insulation resistance of the positive-to-ground battery is different. The first sampling signal of the sampling point between the second resistor and the third resistor is sampled and obtained, thereby accurately determining the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance, thus improving the accuracy and reliability of insulation resistance detection.

[0029] In some embodiments, the second voltage divider module includes a fourth resistor, a fifth resistor, a sixth resistor, and a second switch; wherein:

[0030] The first end of the fourth resistor is connected to the first end of the second switch, the ground end, and the second end of the first voltage divider module, respectively; the second end of the fourth resistor is connected to the first end of the sixth resistor.

[0031] The first terminal of the second switch is connected to the first terminal of the negative-to-ground battery insulation resistor, and the second terminal of the second switch is connected to the first terminal of the fifth resistor.

[0032] The second end of the fifth resistor is connected to the second end of the negative-to-ground battery insulation resistor and the second end of the sixth resistor, respectively. The second end of the sixth resistor is also connected to the second end of the negative-to-ground vehicle insulation resistor.

[0033] The sampling point between the fourth and sixth resistors is used to acquire the second sampling signal.

[0034] By employing the aforementioned technical means, when the main positive relay is in the off state and the second switch is in different states, the connection methods between the second voltage divider module and the battery insulation resistance to negative ground and the vehicle insulation resistance to negative ground are different. The second sampling signal of the sampling point between the fourth resistor and the sixth resistor is sampled and obtained, thereby accurately determining the resistance value of the positive ground insulation resistance and the resistance value of the negative ground insulation resistance, thus improving the accuracy and reliability of insulation resistance detection.

[0035] In some embodiments, the relay module includes a main negative relay; wherein:

[0036] The main negative relay is connected between the second voltage divider module and the vehicle insulation resistor.

[0037] By employing the aforementioned technical means, it was determined that for the circuit structure including the main and negative relays in the detection circuit, the voltage discharged by the charging and discharging module affects the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance when the main and negative relays are disconnected. Based on the specific circuit structure, the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are determined, thereby improving the accuracy and reliability of insulation resistance detection.

[0038] In some embodiments, the vehicle insulation resistance includes the vehicle insulation resistance to ground and the vehicle insulation resistance to ground; wherein:

[0039] The first end of the vehicle insulation resistor facing ground is connected to the first end of the first voltage divider module and the first end of the charging and discharging module, and the second end of the vehicle insulation resistor facing ground is connected to the first end of the vehicle insulation resistor facing negative ground and the ground end, respectively.

[0040] The second terminal of the negative-to-ground vehicle insulation resistance is connected to the second terminal of the main negative relay and the charging / discharging module, respectively.

[0041] Using the aforementioned technical methods, the vehicle insulation resistance includes both the positive-to-ground vehicle insulation resistance and the negative-to-ground vehicle insulation resistance. Based on the parallel connection of the positive-to-ground vehicle insulation resistance and the positive-to-ground battery insulation resistance, the positive-to-ground insulation resistance is determined; similarly, based on the parallel connection of the negative-to-ground vehicle insulation resistance and the negative-to-ground battery insulation resistance, the negative-to-ground insulation resistance is determined. This allows for accurate determination of the resistance values ​​of both positive and negative ground insulation resistance, thereby improving the accuracy and reliability of insulation resistance detection.

[0042] In some embodiments, the first voltage divider module includes a seventh resistor, an eighth resistor, a ninth resistor, and a third switch; wherein:

[0043] The first end of the seventh resistor is connected to the first end of the insulation resistor of the battery facing ground and the first end of the eighth resistor respectively; the second end of the seventh resistor is connected to the first end of the third switch.

[0044] The first end of the eighth resistor is connected to the first end of the vehicle insulation resistor directly facing ground, and the second end of the eighth resistor is connected to the first end of the ninth resistor.

[0045] The second terminal of the third switch is connected to the second terminal of the ninth resistor, the second terminal of the battery insulation resistor facing ground, and the second voltage divider module, respectively.

[0046] The second end of the ninth resistor is also connected to the second end of the vehicle insulation resistor facing ground and the ground end, respectively;

[0047] The sampling point between the eighth and ninth resistors is used to acquire the first sampling signal.

[0048] By employing the aforementioned technical means, when the main negative relay is in the off state and the first switch is in different states, the connection method between the first voltage divider module and the insulation resistance of the positive-to-ground battery is different. The first sampling signal of the sampling point between the eighth and ninth resistors is sampled and obtained, thereby accurately determining the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance, thus improving the accuracy and reliability of insulation resistance detection.

[0049] In some embodiments, the second voltage divider module includes a tenth resistor, an eleventh resistor, a twelfth resistor, and a fourth switch; wherein:

[0050] The first end of the tenth resistor is connected to the first end of the fourth switch, the ground end, and the second end of the first voltage divider module, respectively; the second end of the tenth resistor is connected to the first end of the twelfth resistor.

[0051] The first terminal of the fourth switch is connected to the first terminal of the negative-to-ground battery insulation resistor, and the second terminal of the fourth switch is connected to the first terminal of the eleventh resistor.

[0052] The second terminal of the eleventh resistor is connected to the second terminal of the insulation resistor of the negative-to-ground battery and the second terminal of the twelfth resistor, respectively. The second terminal of the twelfth resistor is also connected to the main negative relay.

[0053] The sampling point between the tenth and twelfth resistors is used to acquire the second sampling signal.

[0054] By employing the aforementioned technical means, when the main negative relay is in the off state and the second switch is in different states, the connection methods between the second voltage divider module and the negative-to-ground battery insulation resistance and the negative-to-ground vehicle insulation resistance are different. The second sampling signal of the sampling point between the tenth resistor and the twelfth resistor is sampled and obtained, thereby accurately determining the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance, thus improving the accuracy and reliability of insulation resistance detection.

[0055] In some embodiments, the charging / discharging module includes a first capacitor, a thirteenth resistor, and a fourteenth resistor; wherein:

[0056] The first terminal of the first capacitor is connected to the first terminal of the vehicle insulation resistor and the first terminal of the thirteenth resistor respectively, and the second terminal of the first capacitor is connected to the second terminal of the vehicle insulation resistor and the second terminal of the fourteenth resistor respectively.

[0057] The second terminal of the thirteenth resistor is connected to the first terminal of the fourteenth resistor;

[0058] The sampling point between the thirteenth and fourteenth resistors is used to acquire the third sampling signal.

[0059] By employing the aforementioned technical means, sampling is performed when the main positive relay or the main negative relay is in the off state and the first voltage divider module and the second voltage divider module are in different states. At least one first sampling signal provided by the first voltage divider module, at least one second sampling signal provided by the second voltage divider module, and at least one third sampling signal provided by the charging and discharging module are obtained to determine the positive-to-ground insulation resistance and the negative-to-ground insulation resistance. This avoids the influence of the voltage discharged by the charging and discharging module outside the main positive relay on the insulation resistance sampling accuracy, thereby improving the accuracy and reliability of insulation resistance sampling.

[0060] In some embodiments, the detection circuit further includes a load resistor; wherein;

[0061] The first end of the load resistor is connected to the first end of the vehicle insulation resistor and the first end of the first capacitor, respectively. The second end of the load resistor is connected to the second end of the vehicle insulation resistor and the second end of the first capacitor, respectively.

[0062] Through the above-mentioned technical means, the detection circuit includes a load resistor. The resistance value of the load resistor is not fixed, so it is not used when constructing the equations for the input current and the output current, thereby improving the accuracy of solving for the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance.

[0063] Secondly, this utility model provides a battery management system, which includes a control branch and the detection circuit described in the first aspect, wherein the control branch is connected to the detection circuit; wherein:

[0064] The control branch is used to determine the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance based on the first sampling signal, the second sampling signal and the third sampling signal obtained by the detection circuit.

[0065] Thirdly, embodiments of the present invention provide an electric drive device, which includes a battery management system as described in the second aspect.

[0066] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this utility model. Attached Figure Description

[0067] Figure 1 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 1 ;

[0068] Figure 2 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 2 ;

[0069] Figure 3 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 3 ;

[0070] Figure 4 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 4 ;

[0071] Figure 5 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 5 ;

[0072] Figure 6 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 6 ;

[0073] Figure 7 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 7 ;

[0074] Figure 8 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 8 ;

[0075] Figure 9 A schematic diagram of the composition structure of a battery management system provided for an embodiment of this utility model;

[0076] Figure 10 This is a schematic diagram of the composition structure of an electric drive device provided in an embodiment of the present utility model. Detailed Implementation

[0077] To gain a more detailed understanding of the features and technical content of the embodiments of this utility model, the implementation of the embodiments of this utility model will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference and illustration only and are not intended to limit the embodiments of this utility model.

[0078] 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 invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0079] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0080] It should also be noted that the terms "first, second, third" used in the embodiments of this utility model are only used to distinguish similar objects and do not represent a specific order of objects. It is understood that "first, second, third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this utility model described herein can be implemented in an order other than that illustrated or described herein.

[0081] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0082] The following is a description of the relevant technologies of this utility model.

[0083] New energy batteries are being used more and more widely in daily life and industry. For example, new energy vehicles equipped with batteries are already widely used. In addition, batteries are being used more and more in the field of energy storage.

[0084] Currently, new energy batteries are being used more and more widely in daily life and industry. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in aerospace and other fields. With the continuous expansion of the application areas of power batteries, the market demand is also constantly increasing.

[0085] In this embodiment of the invention, the battery can be a single battery cell or a battery pack composed of multiple battery cells. A single battery cell is a basic unit capable of converting chemical energy into electrical energy, and can be used to manufacture battery modules or battery packs to supply power to electrical devices. A single battery cell can be a rechargeable battery, which is a battery cell that can be recharged after discharge to reactivate its active materials and continue to be used. Battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc., and this embodiment is not limited to these types.

[0086] In this embodiment of the invention, the battery may also be a single physical module comprising one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0087] Battery Management System (BMS) is used to monitor and control various performance parameters of the battery during the operation of electric vehicles to ensure the safe operation of the battery pack. Among them, insulation sampling of the BMS, which samples the resistance value of the insulation resistance, is a key technology that can prevent problems such as short circuits and overheating caused by insulation failures in the battery pack.

[0088] During battery system operation, the insulation resistance can decrease due to factors such as internal resistance, temperature, electrode materials, and electrolyte. When the insulation resistance drops to a certain level, safety issues such as short circuits and overheating may occur. Therefore, during battery system operation, the Battery Management System (BMS) can accurately detect the insulation resistance in real time to determine the real-time operating status of the battery system, thereby ensuring its safe operation.

[0089] Currently, the insulation sampling circuit of the BMS is designed based on the national standard balanced bridge method. It connects different resistor branches between the battery pack and the insulation resistor, and calculates the insulation resistance value by sampling the voltage values ​​on these different resistor branches. This calculation method requires the voltage of the insulation sampling circuit to come solely from the voltage provided by the battery pack. It does not consider other charging and discharging devices on the vehicle, such as the parasitic capacitance between the battery pack's high-voltage bus and the vehicle body. Transient voltage changes when the relay is disconnected can also affect the sampled voltage value, leading to deviations in the measured insulation resistance value under these conditions.

[0090] Based on this, the present invention provides a detection circuit, a battery management system, and an electric drive device. A first voltage divider module and a second voltage divider module are connected between the battery insulation resistance and the vehicle insulation resistance. A charge / discharge module is connected outside the relay module. When the relay module is in the off state and the first and second voltage divider modules are in different states, the first sampling signal, the second sampling signal, and the third sampling signal generated at the first voltage divider module, the second voltage divider module, and the charge / discharge module in the detection circuit are obtained based on the voltage provided by the battery pack and the voltage provided by the charge / discharge module. In this way, the influence of the voltage change provided by the charge / discharge module outside the relay module on the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance is considered, thereby improving the sampling accuracy and reliability of the insulation resistance.

[0091] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0092] In one embodiment of this utility model, Figure 1 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 1 ; Figure 2 A schematic diagram of the composition structure of a detection circuit provided in an embodiment of this utility model. Figure 2 .like Figure 1 and Figure 2 As shown, the detection circuit includes a relay module 106, a first voltage divider module 101, a second voltage divider module 102, and a charge / discharge module 103; wherein:

[0093] The battery insulation resistor 104 is connected to the first voltage divider module 101, the second voltage divider module 102 and the battery pack 106 respectively. The relay module 106 is connected between the first voltage divider module 101 and / or the second voltage divider module 102 and the vehicle insulation resistor 105. The charging and discharging module 103 is connected to the vehicle insulation resistor 105.

[0094] The detection circuit is used to acquire at least one first sampling signal provided by the first voltage divider module 101, at least one second sampling signal provided by the second voltage divider module 102, and at least one third sampling signal provided by the charge / discharge module 103 when the relay module 106 is in the off state and the first voltage divider module 101 and the second voltage divider module 102 are in different states.

[0095] Among them, at least one first sampling signal, at least one second sampling signal, and at least one third sampling signal are used to determine the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance.

[0096] In the embodiments of this utility model, such as Figure 1 As shown, the relay module 106 may include a relay connected between the first voltage divider module 101 and the vehicle insulation resistance 105; or, as shown... Figure 2 As shown, relay module 106 includes one relay that can be connected between the second voltage divider module 102 and the vehicle insulation resistance 105. Alternatively, relay module 106 may include two relays, one of which is connected between the first voltage divider module 101 and the vehicle insulation resistance 105, and the other relay is connected between the second voltage divider module 102 and the vehicle insulation resistance 105 (not shown in the figures). In this embodiment of the present invention, relay module 106 is in an open state, which can be understood as the relay between the first voltage divider module 101 and the vehicle insulation resistance being disconnected, or the relay between the second voltage divider module 102 and the vehicle insulation resistance 105 being disconnected.

[0097] In this embodiment of the invention, the battery insulation resistance 104 can be understood as the total insulation resistance between the positive and negative terminals of the battery pack 106 and external conductive parts (such as the vehicle body, casing, etc.); the vehicle insulation resistance 105 can be understood as the total insulation resistance between the high-voltage components in the vehicle and the vehicle body or external conductive parts. The positive-to-ground insulation resistance can be obtained by connecting the positive-to-ground portions of the battery insulation resistance 104 and the vehicle insulation resistance 105 in parallel, and the negative-to-ground insulation resistance can be obtained by connecting the negative-to-ground portions of the battery insulation resistance 104 and the vehicle insulation resistance 105 in parallel.

[0098] In this embodiment of the invention, the charging and discharging module 103 may include devices with energy storage and discharging properties, such as capacitors, inductors, etc., or other power supplies. These devices still have residual voltage after the relay module 106 is disconnected, due to the storage of charge or the generation of a back electromotive force. The charging and discharging module 103 can discharge the residual voltage through the active discharge module configured on the vehicle. This method of residual voltage discharge is relatively fast. Alternatively, the charging and discharging module 103 can discharge through the battery insulation resistance 104 and the vehicle insulation resistance 105. In this case, the discharge is slower. If the BMS performs insulation sampling at this time, the discharge will affect the detection of the insulation resistance value, resulting in a deviation in the determined insulation resistance value.

[0099] In this embodiment of the invention, the first voltage divider module 101 and the second voltage divider module 102 may include at least one device for voltage division, used to divide the supply voltage provided by the battery pack 106 and the voltage discharged by the charging / discharging module 103 based on the circuit structure of the connections of each voltage divider device after the relay module 106 is disconnected. The first voltage divider module 101 and the second voltage divider module 102 can be controlled to be in different states based on control signals. In this embodiment of the invention, different states may include an on state, an off state, etc. The first voltage divider module 101 and the second voltage divider module 102 being in different states can be understood as a change in the circuit structure of each voltage divider device in the first voltage divider module 101 and the second voltage divider module 102, or the conduction or disconnection of some voltage divider branches.

[0100] It should be noted that when the relay module 106 is in the off state and the first voltage divider module 101 and the second voltage divider module 102 are in different states, the first voltage divider module 101 in different states and the second voltage divider module 102 in different states are combined to obtain at least one first sampling signal obtained from the sampling point in the first voltage divider module 101 (each first sampling signal is obtained in a different state of the first voltage divider module 101), at least one second sampling signal obtained from the sampling point in the second voltage divider module 102 in different states (each second sampling signal is obtained in a different state of the second voltage divider module 102), and at least one third sampling signal obtained from the sampling point in the charging and discharging module 103.

[0101] For example, when the relay module 106 is off and both the first voltage divider module 101 and the second voltage divider module 102 are on, the first sampling signal, the second sampling signal, and the third sampling signal are acquired; or, when the relay module 106 is off and both the first voltage divider module 101 and the second voltage divider module 102 are off, the first sampling signal, the second sampling signal, and the third sampling signal are acquired; or, when the relay module 106 is off, the first voltage divider module 101 is on and the second voltage divider module 102 is off, the first sampling signal, the second sampling signal, and the third sampling signal are acquired; or, when the relay module 106 is off, the first voltage divider module 101 is off and the second voltage divider module 102 is on, the first sampling signal, the second sampling signal, and the third sampling signal are acquired.

[0102] Furthermore, based on several sets of first sampling signals, second sampling signals, and third sampling signals collected by the first voltage divider module 101 and the second voltage divider module 102 under different states (the number of sets is determined according to the number of unknowns to be solved), the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are determined based on Ohm's law and Kirchhoff's current law circuit theory.

[0103] In this embodiment of the utility model, it is possible to determine whether a short circuit, open circuit, component aging, or line damage has occurred by judging whether the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are within the normal range.

[0104] Thus, in this embodiment of the invention, the first voltage divider module and the second voltage divider module are connected between the battery insulation resistance and the vehicle insulation resistance, and the charging and discharging module is connected outside the relay module. When the relay module is in the off state and the first voltage divider module and the second voltage divider module are in different states, the first sampling signal, the second sampling signal, and the third sampling signal generated at the first voltage divider module, the second voltage divider module, and the charging and discharging module in the detection circuit are obtained based on the voltage provided by the battery pack and the voltage provided by the charging and discharging module, respectively. In this way, the influence of the voltage change provided by the charging and discharging module outside the relay module on the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance is taken into account, thereby improving the sampling accuracy and reliability of the insulation resistance.

[0105] In another embodiment of this utility model, such as Figure 3 and Figure 4 As shown, the battery insulation resistor 104 includes a positive-to-ground battery insulation resistor Rp1 and a negative-to-ground battery insulation resistor Rn1; wherein:

[0106] The first end of the positive-to-ground battery insulation resistor Rp1 is connected to the positive terminal of the battery pack and the first end of the first voltage divider module 101, respectively. The second end of the positive-to-ground battery insulation resistor Rp1 is connected to the second end of the first voltage divider module 101, the first end of the second voltage divider module 102, and the first end of the negative-to-ground battery insulation resistor Rn1, respectively.

[0107] The second terminal of the negative-to-ground battery insulation resistor Rn1 is connected to the negative terminal of the battery pack and the second terminal of the second voltage divider module 102, respectively.

[0108] In this embodiment of the utility model, the battery insulation resistance 104 may include a positive-to-ground battery insulation resistance Rp1 (which can be understood as the insulation resistance between the positive terminal of the battery pack and the external conductive part) and a negative-to-ground battery insulation resistance Rn1 (which can be understood as the insulation resistance between the negative terminal of the battery pack and the external conductive part).

[0109] It should be noted that the resistance value of the battery insulation resistor 104 is jointly determined by the resistance value of the positive-to-ground battery insulation resistor Rp1 and the resistance value of the negative-to-ground battery insulation resistor Rn1. When the resistance value of either battery insulation resistor decreases, the total resistance value will decrease significantly.

[0110] In this embodiment of the utility model, the battery insulation resistance 104 is connected in parallel with the vehicle insulation resistance 105. The positive-to-ground battery insulation resistance Rp1 can be connected in parallel with the positive-to-ground portion of the vehicle insulation resistance 105 to determine the positive-to-ground insulation resistance; the negative-to-ground battery insulation resistance Rn1 can be connected in parallel with the negative-to-ground portion of the vehicle insulation resistance 105 to determine the negative-to-ground insulation resistance.

[0111] In this embodiment of the present invention, when the relay module 106 is in the off state and the first voltage divider module 101 and the second voltage divider module 102 are in different states, at least one set of first sampling signals, second sampling signals and third sampling signals are collected to determine the resistance value of the positive-to-ground battery insulation resistance Rp1 and the resistance value of the positive-to-ground portion of the vehicle insulation resistance 105, as well as the resistance value of the negative-to-ground insulation resistance; or, the resistance value of the negative-to-ground battery insulation resistance Rn1 and the resistance value of the negative-to-ground portion of the vehicle insulation resistance 105, as well as the resistance value of the positive-to-ground insulation resistance, are determined.

[0112] It should be noted that in the embodiments where the relay module includes a main positive relay or a main negative relay, the battery insulation resistance includes the positive-to-ground battery insulation resistance and the negative-to-ground battery insulation resistance, and its connection relationship with other modules is as described in this embodiment.

[0113] Thus, in this embodiment of the present invention, the battery insulation resistance includes a positive-to-ground battery insulation resistance and a negative-to-ground battery insulation resistance. The positive-to-ground battery insulation resistance is connected in parallel with the first voltage divider module, and the negative-to-ground battery insulation resistance is connected in parallel with the second voltage divider module 102. This makes the first sampling voltage obtained by the first voltage divider module the voltage across the positive-to-ground battery insulation resistance, and the second sampling voltage obtained by the second voltage divider module 102 the voltage across the negative-to-ground battery insulation resistance. This facilitates the determination of the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance.

[0114] In some embodiments, based on Figure 3 The illustrated embodiment, as Figure 5 As shown, the relay module includes a main positive relay K1; wherein:

[0115] The main positive relay K1 is connected between the first voltage divider module 101 and the vehicle insulation resistor.

[0116] It should be noted that, as mentioned above, the relay module may include one relay or two relays. In this embodiment of the invention, as... Figure 5 As shown, the relay module may include a main positive relay K1. When the main positive relay K1 is off, or in some embodiments, the relay module includes two relays, with the relay between the first voltage divider module 101 and the vehicle insulation resistance off, and the relay between the second voltage divider module 102 and the vehicle insulation resistance on, the charging / discharging module 103 is connected to the detection circuit. The discharged voltage will affect the determination of the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance. It can be understood that the above two situations are equivalent. In this utility model and the following embodiments, the example of the relay module including a main positive relay K1 with the main positive relay K1 in the off state is used to illustrate the insulation resistance sampling.

[0117] In this embodiment of the utility model, Figure 6 The diagram shown is the equivalent circuit diagram of the detection circuit when the main positive relay K1 is turned off.

[0118] Thus, in this embodiment of the invention, it is determined that for a circuit structure including a main positive relay in the detection circuit, when the main positive relay is disconnected, the voltage discharged by the charging and discharging module affects the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance. Based on the specific circuit structure, the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are determined, thereby improving the accuracy and reliability of insulation resistance detection.

[0119] In some embodiments, such as Figure 5 and Figure 6As shown, the vehicle insulation resistance includes the positive-to-ground vehicle insulation resistance Rp2 and the negative-to-ground vehicle insulation resistance Rn2; where:

[0120] The first end of the vehicle insulation resistor Rp2, which is positive to ground, is connected to the first end of the main positive relay K1 and the first end of the charging / discharging module 103, respectively. The second end of the vehicle insulation resistor Rp2, which is positive to ground, is connected to the first end of the vehicle insulation resistor Rn2, which is negative to ground, and the ground end, respectively.

[0121] The second terminal of the negative-to-ground vehicle insulation resistance Rn2 is connected to the second terminal of the second voltage divider module 102 and the second terminal of the charge / discharge module 103, respectively.

[0122] In this embodiment of the utility model, the vehicle insulation resistance includes the positive-to-ground vehicle insulation resistance Rp2 (the insulation resistance between the positive terminal of the high-voltage component in the vehicle and the vehicle body or external conductive parts) and the negative-to-ground vehicle insulation resistance Rn2 (the insulation resistance between the negative terminal of the high-voltage component in the vehicle and the vehicle body or external conductive parts).

[0123] It should be noted that when the detection circuit includes the main positive relay K1 and the main positive relay K1 is in the on state, the vehicle insulation resistance Rp2 to ground is connected in parallel with the battery insulation resistance to ground, and the resistance value of the insulation resistance to ground can be determined based on this. When the detection circuit includes the main positive relay K1 and the main positive relay K1 is off, the insulation resistance to ground is divided into two parts: the vehicle insulation resistance Rp2 to ground and the battery insulation resistance to ground. The vehicle insulation resistance Rn2 to negative ground is connected in parallel with the battery insulation resistance to negative ground, and the resistance value of the insulation resistance to negative ground can be determined based on this. Therefore, in this case, the insulation performance can be determined to be normal by judging whether the resistance values ​​of the vehicle insulation resistance Rp2 to ground, the battery insulation resistance to ground, and the insulation resistance to negative ground are within the normal resistance value range.

[0124] In this embodiment of the invention, when the main positive relay K1 is in the off state and the first voltage module and the second voltage module are in different states, at least one set of first sampling signals, second sampling signals, and third sampling signals are acquired. Based on Kirchhoff's current law circuit theory, for any node in the detection circuit, the inflow current equals the sum of the outflow currents. A corresponding equation is constructed for each set of acquired sampling signals, and the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are solved by solving several equations simultaneously. For example, based on the node between the positive-to-ground vehicle insulation resistance Rp2 and the negative-to-ground vehicle insulation resistance Rn2, the current equation corresponding to each set of sampling signals can be constructed based on Kirchhoff's current law circuit theory.

[0125] Thus, in this embodiment of the invention, the vehicle insulation resistance includes a positive-to-ground vehicle insulation resistance and a negative-to-ground vehicle insulation resistance. The positive-to-ground insulation resistance is determined based on the parallel connection of the positive-to-ground vehicle insulation resistance and the positive-to-ground battery insulation resistance; similarly, the negative-to-ground insulation resistance is determined based on the parallel connection of the negative-to-ground vehicle insulation resistance and the negative-to-ground battery insulation resistance. This allows for accurate determination of the resistance values ​​of both the positive and negative ground insulation resistances, thereby improving the accuracy and reliability of insulation resistance detection.

[0126] In some embodiments, such as Figure 5 and Figure 6 As shown, the first voltage divider module 101 includes a first resistor R1, a second resistor R2, a third resistor R3, and a first switch S1; wherein:

[0127] The first end of the first resistor R1 is connected to the first end of the insulation resistor of the battery facing ground and the first end of the second resistor R2 respectively. The second end of the first resistor R1 is connected to the first end of the first switch S1.

[0128] The first end of the second resistor R2 is connected to the main positive relay K1, and the second end of the second resistor R2 is connected to the first end of the third resistor R3.

[0129] The second terminal of the first switch S1 is connected to the second terminal of the third resistor R3, the second terminal of the battery insulation resistor facing ground, and the second voltage divider module 102, respectively.

[0130] The second end of the third resistor R3 is also connected to the second end of the vehicle insulation resistor Rp2 and the ground end, respectively.

[0131] The sampling point between the second resistor R2 and the third resistor R3 is used to acquire the first sampling signal.

[0132] In this embodiment of the present invention, the first voltage divider module 101 is in the on state, which can be understood as controlling the first switch S1 to be on based on the control signal; the first voltage divider module 101 is in the off state, which can be understood as controlling the first switch S1 to be off based on the control signal.

[0133] In this embodiment of the invention, when the main positive relay K1 is in the off state and the first voltage divider module 101 is in the on state, the battery insulation resistance to ground is connected in parallel with the branch containing the second resistor R2 and the third resistor R3. The voltage value between the second resistor R2 and the third resistor R3 is sampled, which is the first sampling signal corresponding to the on state. When the main positive relay K1 is in the off state and the first voltage divider module 101 is in the off state, the battery insulation resistance to ground is connected in parallel with the branch containing the first resistor R1 and the branch containing the second resistor R2 and the third resistor R3. The voltage value between the second resistor R2 and the third resistor R3 is sampled, which is the first sampling signal corresponding to the off state. The voltage values ​​of the first sampling signals obtained in different states of the first voltage divider module 101 are different.

[0134] Thus, in this embodiment of the invention, when the main positive relay is in the off state and the first switch is in different states, the connection method between the first voltage divider module and the insulation resistance of the battery to ground is different. The first sampling signal of the sampling point between the second resistor and the third resistor is sampled and obtained, thereby accurately determining the resistance value of the insulation resistance to ground and the resistance value of the insulation resistance to ground, thereby improving the accuracy and reliability of insulation resistance detection.

[0135] In some embodiments, such as Figure 5 and Figure 6 As shown, the second voltage divider module 102 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a second switch S2; wherein:

[0136] The first end of the fourth resistor R4 is connected to the first end of the second switch S2, the ground end and the second end of the first voltage divider module 101 respectively, and the second end of the fourth resistor R4 is connected to the first end of the sixth resistor R6.

[0137] The first terminal of the second switch S2 is connected to the first terminal of the negative-to-ground battery insulation resistor, and the second terminal of the second switch S2 is connected to the first terminal of the fifth resistor R5.

[0138] The second end of the fifth resistor R5 is connected to the second end of the negative-to-ground battery insulation resistor and the second end of the sixth resistor R6 respectively. The second end of the sixth resistor R6 is also connected to the second end of the negative-to-ground vehicle insulation resistor Rn2.

[0139] The sampling point between the fourth resistor R4 and the sixth resistor R6 is used to acquire the second sampling signal.

[0140] In this embodiment of the present invention, the second voltage divider module 102 is in the on state, which can be understood as controlling the second switch S2 to be on based on the control signal; the second voltage divider module 102 is in the off state, which can be understood as controlling the second switch S2 to be off based on the control signal.

[0141] In this embodiment of the invention, when the main positive relay K1 is in the off state and the second voltage divider module 102 is in the off state, the branch containing the negative-to-ground battery insulation resistance, the fourth resistor R4 and the sixth resistor R6, and the negative-to-ground vehicle insulation resistance Rn2 are connected in parallel, and a second sampling signal between the fourth resistor R4 and the sixth resistor R6 is obtained. When the main positive relay K1 is in the off state and the second voltage divider module 102 is in the on state, the branch containing the negative-to-ground battery insulation resistance, the fifth resistor R5, the branch containing the fourth resistor R4 and the sixth resistor R6, and the negative-to-ground vehicle insulation resistance Rn2 are connected in parallel, and a second sampling signal between the fourth resistor R4 and the sixth resistor R6 is obtained. The voltage values ​​of the second sampling signals obtained in different states of the second voltage divider module 102 are different.

[0142] Thus, in this embodiment of the utility model, when the main positive relay is in the off state and the second switch is in different states, the connection methods between the second voltage divider module and the negative-to-ground battery insulation resistance and the negative-to-ground vehicle insulation resistance are different. The second sampling signal of the sampling point between the fourth resistor and the sixth resistor is sampled and obtained, thereby accurately determining the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance, thereby improving the accuracy and reliability of insulation resistance detection.

[0143] In some embodiments, such as Figure 5 and Figure 6 As shown, the charging / discharging module 103 includes a first capacitor Cx, a thirteenth resistor R13, and a fourteenth resistor R14; wherein:

[0144] The first terminal of the first capacitor Cx is connected to the first terminal of the vehicle insulation resistor Rp2 (positive to ground) and the first terminal of the thirteenth resistor R13, respectively. The second terminal of the first capacitor Cx is connected to the second terminal of the vehicle insulation resistor Rn2 (negative to ground) and the second terminal of the fourteenth resistor R14, respectively.

[0145] The second terminal of the thirteenth resistor R13 is connected to the first terminal of the fourteenth resistor R14;

[0146] Among them, the sampling point between the thirteenth resistor R13 and the fourteenth resistor R14 is used to collect the third sampling signal.

[0147] It should be noted that for circuit structures controlled by only a single relay in the circuit, for a period of time after the main positive relay K1 is in the off state, there may be residual voltage on the first capacitor Cx in the charging / discharging module 103 outside the main positive relay K1. At this time, there are other voltage sources in the detection circuit besides the battery pack, which interfere with the BMS's sampling of the first and second sampling signals through the insulation resistance, thereby affecting the accuracy of the BMS's insulation resistance detection. In this embodiment of the present invention, the charging / discharging module 103 that provides voltage is taken into account in the detection circuit, and the third sampling signal between the thirteenth resistor R13 and the fourteenth resistor R14 is sampled. Even after the main positive relay K1 is turned off, if there is residual voltage outside the relay, the influence of the charging / discharging module 103 on the insulation resistance sampling accuracy can be avoided, ensuring the accuracy of the determined resistance values ​​of the positive to ground insulation resistance and the negative to ground insulation resistance.

[0148] In some embodiments, the first sampling signal provided by the first voltage divider module, the second sampling signal provided by the second voltage divider module, and the third sampling signal provided by the charging and discharging module can be obtained in four cases, determined by the combination of the first voltage divider module being in an on or off state and the second voltage divider module being in an on or off state. Further, based on the first sampling signal, the second sampling signal, and the third sampling signal obtained in at least three of these cases, the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance are determined by solving a system of simultaneous equations.

[0149] Based on the first sampling signal Up-adc, the second sampling signal Un-adc, and the third sampling signal Ucx-adc, and using resistor voltage divider sampling, the voltage Up across the insulation resistor of the battery facing to ground can be determined as: Up=Up-adc*(R2+R3) / R3; the voltage Un across the insulation resistor of the battery facing to ground can be determined as: Un=Un-adc*(R4+R6) / R6; and the voltage Ucx across the first capacitor Cx can be determined as: Ucx=Ucx-adc*(R13+R14) / R14.

[0150] In some embodiments, by controlling the first and second switches to be turned off, that is, when both the first voltage divider module 101 and the second voltage divider module 102 are in the off state, the voltage Up1 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc1 obtained by sampling; the voltage Un1 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc1 obtained by sampling; and the voltage Ucx1 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc1 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 1 can be constructed: Up1 / (Rp1 / / (R2+R3))+(Un1-Ucx1) / Rp2=Un1 / (Rn1 / / (R4+R6) / / Rn2).

[0151] It should be noted that, Figure 6 The detection circuit shown is Figure 5 The equivalent circuit diagram of the main positive relay K1 in the off state is as follows: Figure 6 As shown, the negative-to-ground insulation resistance Rn can be determined based on Rn=Rn1 / / Rn2, then the above equation 1 can be updated to: Up1 / (Rp1 / / (R2+R3))+(Un1-Ucx1) / Rp2=Un1 / (Rn / / (R4+R6)).

[0152] In some embodiments, by controlling the first switch to be on and the second switch to be off, that is, when the first voltage divider module 101 is in the on state and the second voltage divider module 102 is in the off state, the voltage Up2 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc2 obtained by sampling; and the voltage Un2 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc2 obtained by sampling; and the voltage Ucx2 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc2 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 2 can be constructed: Up2 / (Rp1 / / (R2+R3) / / R1)+(Un2-Ucx2) / Rp2=Un2 / (Rn / / (R4+R6)).

[0153] In some embodiments, by controlling the second switch to be on and the first switch to be off, that is, when the first voltage divider module 101 is off and the second voltage divider module 102 is on, the voltage Up3 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc3 obtained by sampling; the voltage Un3 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc3 obtained by sampling; and the voltage Ucx3 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc3 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 3 can be constructed: Up3 / (Rp1 / / (R2+R3))+(Un3-Ucx3) / Rp2=Un3 / (Rn / / (R4+R6) / / R5).

[0154] In some embodiments, by controlling both the first switch and the second switch to be on, that is, when both the first switch module and the second switch module are in the on state, the voltage Up4 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc4 obtained by sampling; the voltage Un4 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc4 obtained by sampling; and the voltage Ucx4 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc4 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 4 can be constructed: Up4 / (Rp1 / / (R2+R3) / / R1)+(Un4-Ucx4) / Rp2=Un4 / (Rn / / (R4+R6) / / R5).

[0155] In this embodiment of the utility model, by simultaneously solving any three of the above-constructed equations 1 to 4, the positive-to-ground battery insulation resistance Rp1, the positive-to-ground vehicle insulation resistance Rp2, and the negative-to-ground insulation resistance Rn can be determined. Since the main positive relay K1 is turned off at this time, the positive-to-ground insulation resistance is divided into the positive-to-ground battery insulation resistance Rp1 and the positive-to-ground vehicle insulation resistance Rp2. Therefore, it can be determined whether the positive-to-ground battery insulation resistance Rp1, the positive-to-ground vehicle insulation resistance Rp2, and the negative-to-ground insulation resistance Rn are within the normal range, and whether there is any abnormality in the insulation performance of the vehicle.

[0156] Thus, in this embodiment of the invention, sampling is performed when the main positive relay is in the off state and the first voltage divider module and the second voltage divider module are in different states. At least one first sampling signal provided by the first voltage divider module, at least one second sampling signal provided by the second voltage divider module, and at least one third sampling signal provided by the charging and discharging module are obtained. The battery insulation resistance to ground, the vehicle insulation resistance to ground, and the insulation resistance to negative ground are determined. This avoids the influence of the voltage discharged by the charging and discharging module outside the main positive relay on the insulation resistance sampling accuracy, and improves the accuracy and reliability of insulation resistance sampling.

[0157] In another embodiment of this utility model, based on Figure 4 The illustrated embodiment, as Figure 7 As shown, the relay module includes a main negative relay K2; wherein:

[0158] The main negative relay K2 is connected between the second voltage divider module 102 and the vehicle insulation resistor.

[0159] It should be noted that, as mentioned above, the relay module may include one relay or two relays. In this embodiment of the invention, as... Figure 7 As shown, the relay module may include a main negative relay K2. When the main negative relay K2 is off, or in some embodiments, the relay module includes two relays, with the relay between the first voltage divider module 101 and the vehicle insulation resistance conducting and the relay between the second voltage divider module 102 and the vehicle insulation resistance being off, the charging / discharging module 103 is connected to the detection circuit. The discharged voltage will affect the determination of the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance. It can be understood that the above two situations are equivalent. In this utility model and the following embodiments, the example of the relay module including a main negative relay K2 and the main negative relay K2 being off is used to illustrate the insulation resistance sampling.

[0160] In this embodiment of the utility model, Figure 8 The diagram shown is the equivalent circuit diagram of the detection circuit when the main negative relay K2 is turned off.

[0161] Thus, in this embodiment of the invention, it is determined that for a circuit structure including a main negative relay in the detection circuit, when the main negative relay is disconnected, the voltage discharged by the charging and discharging module affects the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance. Based on the specific circuit structure, the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are determined, thereby improving the accuracy and reliability of insulation resistance detection.

[0162] In some embodiments, such as Figure 7 and Figure 8As shown, the vehicle insulation resistance includes the positive-to-ground vehicle insulation resistance Rp2 and the negative-to-ground vehicle insulation resistance Rn2; where:

[0163] The first end of the vehicle insulation resistor Rp2, which is directly connected to ground, is connected to the first end of the first voltage divider module 101 and the first end of the charging and discharging module 103. The second end of the vehicle insulation resistor Rp2, which is directly connected to ground, is connected to the first end of the vehicle insulation resistor Rn2, which is negatively connected to ground, and the ground end, respectively.

[0164] The second terminal of the negative-to-ground vehicle insulation resistance Rn2 is connected to the second terminal of the main negative relay K2 and the charging / discharging module 103, respectively.

[0165] In this embodiment of the utility model, the vehicle insulation resistance includes the positive-to-ground vehicle insulation resistance Rp2 (the insulation resistance between the positive terminal of the high-voltage component in the vehicle and the vehicle body or external conductive parts) and the negative-to-ground vehicle insulation resistance Rn2 (the insulation resistance between the negative terminal of the high-voltage component in the vehicle and the vehicle body or external conductive parts).

[0166] It should be noted that when the detection circuit includes the main negative relay K2 and the main negative relay K2 is in the on state, the vehicle insulation resistance Rn2 to ground and the battery insulation resistance Rn1 to ground are connected in parallel, and the resistance value of the negative insulation resistance to ground can be determined based on this. When the detection circuit includes the main negative relay K2 and the main negative relay K2 is off, the negative insulation resistance to ground is divided into two parts: the vehicle insulation resistance Rn2 to ground and the battery insulation resistance Rn1 to ground. The vehicle insulation resistance Rp2 to ground and the battery insulation resistance Rp1 to ground are connected in parallel, and the resistance value of the positive insulation resistance to ground can be determined based on this. Therefore, in this case, the insulation performance can be determined by judging whether the resistance values ​​of the vehicle insulation resistance Rn2 to ground, the battery insulation resistance Rn1 to ground, and the positive insulation resistance to ground are within the normal resistance value range.

[0167] In this embodiment of the invention, when the main negative relay K2 is in the off state and the first voltage module 101 and the second voltage module 102 are in different states, at least one set of first sampling signals, second sampling signals, and third sampling signals are acquired. Based on Kirchhoff's current law circuit theory, for any node in the detection circuit, the inflow current equals the sum of the outflow currents. A corresponding equation is constructed for each set of acquired sampling signals, and the resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance are solved by solving several equations simultaneously. For example, based on the node between the positive-to-ground vehicle insulation resistance Rp2 and the negative-to-ground vehicle insulation resistance Rn2, the current equation corresponding to each set of sampling signals can be constructed based on Kirchhoff's current law circuit theory.

[0168] Thus, in this embodiment of the invention, the vehicle insulation resistance includes a positive-to-ground vehicle insulation resistance and a negative-to-ground vehicle insulation resistance. The positive-to-ground insulation resistance is determined based on the parallel connection of the positive-to-ground vehicle insulation resistance and the positive-to-ground battery insulation resistance; similarly, the negative-to-ground insulation resistance is determined based on the parallel connection of the negative-to-ground vehicle insulation resistance and the negative-to-ground battery insulation resistance. This allows for accurate determination of the resistance values ​​of both the positive and negative ground insulation resistances, thereby improving the accuracy and reliability of insulation resistance detection.

[0169] In some embodiments, such as Figure 7 and Figure 8 As shown, the first voltage divider module 101 includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a third switch S3; wherein:

[0170] The first end of the seventh resistor R7 is connected to the first end of the insulation resistor of the battery facing ground and the first end of the eighth resistor R8 respectively. The second end of the seventh resistor R7 is connected to the first end of the third switch S3.

[0171] The first end of the eighth resistor R8 is connected to the first end of the vehicle insulation resistor Rp2 which is directly grounded, and the second end of the eighth resistor R8 is connected to the first end of the ninth resistor R9.

[0172] The second terminal of the third switch S3 is connected to the second terminal of the ninth resistor R9, the second terminal of the battery insulation resistor facing ground, and the second voltage divider module 102, respectively.

[0173] The second terminal of the ninth resistor R9 is also connected to the second terminal and the ground terminal of the vehicle insulation resistor Rp2, which is directly facing the ground.

[0174] The sampling point between the eighth resistor R8 and the ninth resistor R9 is used to acquire the first sampling signal.

[0175] In this embodiment of the present invention, the first voltage divider module 101 is in the on state, which can be understood as controlling the third switch S3 to be on based on the control signal; the first voltage divider module 101 is in the off state, which can be understood as controlling the third switch S3 to be off based on the control signal.

[0176] In this embodiment of the invention, when the main negative relay K2 is in the off state and the first voltage divider module 101 is in the on state, the battery insulation resistance to ground is connected in parallel with the branch containing the eighth resistor R8 and the ninth resistor R9. The voltage value between the eighth resistor R8 and the ninth resistor R9 is sampled, which is the first sampling signal corresponding to the on state. When the main negative relay K2 is in the off state and the first voltage divider module 101 is in the off state, the battery insulation resistance to ground is connected in parallel with the branch containing the seventh resistor R7 and the branch containing the eighth resistor R8 and the ninth resistor R9. The voltage value between the eighth resistor R8 and the ninth resistor R9 is sampled, which is the first sampling signal corresponding to the off state. The voltage values ​​of the first sampling signals obtained in different states of the first voltage divider module 101 are different.

[0177] Thus, in this embodiment of the utility model, when the main negative relay is in the off state and the first switch is in different states, the connection method between the first voltage divider module and the insulation resistance of the positive-to-ground battery is different. The first sampling signal of the sampling point between the eighth resistor and the ninth resistor is sampled and obtained, thereby accurately determining the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance, thereby improving the accuracy and reliability of insulation resistance detection.

[0178] In some embodiments, such as Figure 7 and Figure 8 As shown, the second voltage divider module 102 includes a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a fourth switch S4; wherein:

[0179] The first end of the tenth resistor R10 is connected to the first end of the fourth switch S4, the ground end, and the second end of the first voltage divider module 101, respectively. The second end of the tenth resistor R10 is connected to the first end of the twelfth resistor R12.

[0180] The first terminal of the fourth switch S4 is connected to the first terminal of the negative-to-ground battery insulation resistor, and the second terminal of the fourth switch S4 is connected to the first terminal of the eleventh resistor R11.

[0181] The second terminal of the eleventh resistor R11 is connected to the second terminal of the negative-to-ground battery insulation resistor and the second terminal of the twelfth resistor R12 respectively. The second terminal of the twelfth resistor is also connected to the main negative relay K2.

[0182] The sampling point between the tenth resistor R10 and the twelfth resistor R12 is used to acquire the second sampling signal.

[0183] In this embodiment of the present invention, the second voltage divider module 102 is in the on state, which can be understood as controlling the fourth switch S4 to be on based on the control signal; the second voltage divider module 102 is in the off state, which can be understood as controlling the fourth switch S4 to be off based on the control signal.

[0184] In this embodiment of the invention, when the main negative relay K2 is in the off state and the second voltage divider module 102 is in the off state, the battery insulation resistance to ground, the branch containing the tenth resistor R10 and the twelfth resistor, and the vehicle insulation resistance to ground Rn2 are connected in parallel, and a second sampling signal between the tenth resistor R10 and the twelfth resistor R12 is obtained by sampling. When the main negative relay K2 is in the off state and the second voltage divider module 102 is in the on state, the battery insulation resistance to ground, the branch containing the eleventh resistor R11, the branch containing the tenth resistor R10 and the twelfth resistor R12, and the vehicle insulation resistance to ground Rn2 are connected in parallel, and a second sampling signal between the tenth resistor R10 and the twelfth resistor R12 is obtained by sampling. The voltage values ​​of the second sampling signals obtained in different states of the second voltage divider module 102 are different.

[0185] Thus, in this embodiment of the utility model, when the main negative relay is in the off state and the second switch is in different states, the connection methods between the second voltage divider module and the negative-to-ground battery insulation resistance and the negative-to-ground vehicle insulation resistance are different. The second sampling signal of the sampling point between the tenth resistor and the twelfth resistor is sampled and obtained, thereby accurately determining the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance, thereby improving the accuracy and reliability of insulation resistance detection.

[0186] In some embodiments, such as Figure 7 and Figure 8 As shown, the charging / discharging module 103 includes a first capacitor Cx, a thirteenth resistor R13, and a fourteenth resistor R14; wherein:

[0187] The first terminal of the first capacitor Cx is connected to the first terminal of the vehicle insulation resistor Rp2 (positive to ground) and the first terminal of the thirteenth resistor R13, respectively. The second terminal of the first capacitor Cx is connected to the second terminal of the vehicle insulation resistor Rn2 (negative to ground) and the second terminal of the fourteenth resistor R14, respectively.

[0188] The second terminal of the thirteenth resistor R13 is connected to the first terminal of the fourteenth resistor R14;

[0189] Among them, the sampling point between the thirteenth resistor R13 and the fourteenth resistor R14 is used to collect the third sampling signal.

[0190] It should be noted that for circuit structures controlled by only a single relay in the circuit, for a period of time after the main negative relay K2 is in the open state, there may be residual voltage on the first capacitor Cx in the charging / discharging module 103 outside the main negative relay K2. At this time, there are other voltage sources in the detection circuit besides the battery pack, which interfere with the BMS's sampling of the first and second sampling signals through the insulation resistance, thereby affecting the accuracy of the BMS's insulation resistance detection. In this embodiment of the present invention, the charging / discharging module 103 that provides voltage is taken into account in the detection circuit, and the third sampling signal between the thirteenth resistor R13 and the fourteenth resistor R14 is sampled. Even after the main negative relay K2 is open, if there is residual voltage outside the relay, the influence of the charging / discharging module 103 on the insulation resistance sampling accuracy can be avoided, ensuring the accuracy of the determined resistance values ​​of the positive to ground insulation resistance and the negative to ground insulation resistance.

[0191] In this embodiment of the utility model, based on the first sampling signal Up-adc, the second sampling signal Un-adc, and the third sampling signal Ucx-adc, and based on resistor voltage division sampling, the voltage Up across the positive-to-ground battery insulation resistor can be determined as: Up=Up-adc*(R8+R9) / R9; the voltage Un across the negative-to-ground battery insulation resistor can be determined as: Un=Un-adc*(R10+R12) / R12; and the voltage Ucx across the first capacitor Cx can be determined as: Ucx=Ucx-adc*(R13+R14) / R14.

[0192] In some embodiments, by controlling both the third switch S3 and the fourth switch S4 to be off, that is, when both the first voltage divider module 101 and the second voltage divider module 102 are in the off state, the voltage Up5 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc5 obtained by sampling; the voltage Un5 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc5 obtained by sampling; and the voltage Ucx5 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc5 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 5 can be constructed: Up5 / (Rp1 / / (R8+R9) / / Rp2)+(Up5-Ucx5) / Rn2=Un5 / (Rn1 / / (R10+R12)).

[0193] It should be noted that, Figure 8 The detection circuit shown is Figure 7 The equivalent circuit diagram of the main negative relay K2 in the off state is as follows: Figure 8As shown, the insulation resistance Rp to ground can be determined based on Rp = Rp1 / / Rp2. Then, the above equation 5 can be updated to: Up1 / (Rp / / (R8+R9))+(Up1-Ucx1) / Rn2=Un1 / (Rn1 / / (R10+R12)).

[0194] In some embodiments, by controlling the third switch S3 to be on and the fourth switch S4 to be off, that is, when the first voltage divider module 101 is on and the second voltage divider module 102 is off, the voltage Up6 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc6 obtained by sampling; the voltage Un6 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc6 obtained by sampling; and the voltage Ucx6 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc6 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 6 can be constructed: Up6 / (Rp / / (R8+R9) / / R7)+(Up6-Ucx6) / Rn2=Un6 / (Rn1 / / (R10+R12)).

[0195] In some embodiments, by controlling the third switch S3 to be off and the fourth switch S4 to be on, that is, when the first voltage divider module 101 is off and the second voltage divider module 102 is on, the voltage Up7 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc7 obtained by sampling; the voltage Un7 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc7 obtained by sampling; and the voltage Ucx7 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc7 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 7 can be constructed: Up7 / (Rp / / (R8+R9))+(Un7-Ucx7) / Rn2=Un7 / (Rn1 / / (R10+R12) / / R11).

[0196] In some embodiments, by controlling both the third switch S3 and the fourth switch S4 to be on, that is, when both the first voltage divider module 101 and the second voltage divider module 102 are on, the voltage Up8 across the positive-to-ground battery insulation resistor is determined based on the first sampling signal Up-adc8 obtained by sampling; the voltage Un8 across the negative-to-ground battery insulation resistor is determined based on the second sampling signal Un-adc8 obtained by sampling; and the voltage Ucx8 across the first capacitor Cx is determined based on the third sampling signal Ucx-adc8 obtained by sampling. Based on Kirchhoff's current law circuit theory, for the node between the positive-to-ground vehicle insulation resistor Rp2, the negative-to-ground vehicle insulation resistor Rn2 and the ground terminal, the current input and output equation 8 can be constructed: Up8 / (Rp / / (R8+R9) / / R7)+(Un8-Ucx8) / Rn2=Un8 / (Rn1 / / (R10+R12) / / R11).

[0197] In this embodiment of the utility model, by simultaneously solving any three of the above-constructed equations 5 to 8, the positive-to-ground insulation resistance Rp, the negative-to-ground battery insulation resistance Rn1, and the negative-to-ground vehicle insulation resistance Rn2 can be determined. Since the main negative relay K2 is turned off at this time, the negative-to-ground insulation resistance is divided into the negative-to-ground battery insulation resistance Rn1 and the negative-to-ground vehicle insulation resistance Rn2. Therefore, it can be determined whether the negative-to-ground battery insulation resistance Rn1, the negative-to-ground vehicle insulation resistance Rn2, and the positive-to-ground insulation resistance Rp are within the normal range, and whether there is any abnormality in the vehicle's insulation performance.

[0198] Thus, in this embodiment of the invention, sampling is performed when the main negative relay is in the off state and the first voltage divider module and the second voltage divider module are in different states. At least one first sampling signal provided by the first voltage divider module, at least one second sampling signal provided by the second voltage divider module, and at least one third sampling signal provided by the charging and discharging module are obtained to determine the battery insulation resistance to ground, the vehicle insulation resistance to ground, and the insulation resistance to ground. This avoids the influence of the voltage discharged by the charging and discharging module outside the main positive relay on the insulation resistance sampling accuracy and improves the accuracy and reliability of insulation resistance sampling.

[0199] In some embodiments, such as Figures 5-8 As shown, the detection circuit 10 also includes a load resistor R15; wherein;

[0200] The first end of the load resistor R15 is connected to the first end of the vehicle insulation resistor Rp2 (positive to ground) and the first end of the first capacitor Cx, respectively. The second end of the load resistor R15 is connected to the second end of the vehicle insulation resistor Rn2 (negative to ground) and the second end of the first capacitor Cx, respectively.

[0201] In this embodiment of the utility model, the load resistor R15 can be understood as the load on the vehicle, such as the load of the lighting system, motor and other electronic equipment. Its resistance value is related to the specific design of the vehicle's electrical system, the type of load and the working conditions.

[0202] It should be noted that the aforementioned embodiments are based on Kirchhoff's current law circuit theory. For the equations of input current and output current constructed between the nodes of the positive-to-ground vehicle insulation resistance Rp2, the negative-to-ground vehicle insulation resistance Rn2 and the ground terminal, when constructing equations for the nodes across the load resistor R15, the corresponding equations can also be constructed based on the relationship between the load resistor R15 and other resistors, and the positive-to-ground insulation resistance and the negative-to-ground insulation resistance can be solved.

[0203] Thus, in this embodiment of the invention, the detection circuit includes a load resistor, the resistance value of which is not fixed. Therefore, this value is not used when constructing the equations for the input current and the output current, thereby improving the accuracy of the calculated resistance values ​​for the positive-to-ground insulation resistance and the negative-to-ground insulation resistance.

[0204] In another embodiment of this utility model, a battery management system is provided, such as... Figure 9 As shown, the battery management system 20 includes a control branch 201 and a detection circuit 10 as described in the previous embodiment, wherein the control branch 201 is connected to the detection circuit 10; wherein:

[0205] The control branch 201 is used to determine the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance based on the first sampling signal, the second sampling signal and the third sampling signal obtained by the detection circuit 10.

[0206] For detection circuits that only include a main positive relay or a main negative relay, when the relay is open, the insulation resistance of the vehicle end (negative to ground) corresponding to the side without the relay will also be connected to the BMS sampling circuit during insulation resistance sampling. If there is voltage outside the relay (residual voltage on the first capacitor Cx, or other external power sources), the insulation sampling value calculated by the BMS will be deviated (the voltage component on Cx will be superimposed on the negative to ground battery insulation resistance). In this embodiment, for detection circuits that only include a main positive relay or a main negative relay, monitoring of the voltage outside the relay is added. Even if there is voltage outside the relay when the main positive relay or main negative relay is open, the detection circuit based on this embodiment can still perform insulation resistance sampling normally, ensuring the accuracy of the insulation sampling results.

[0207] In some embodiments, such as Figure 5As shown, for a detection circuit with a main positive relay, the BMS performs insulation resistance detection when the main positive relay is in the open state:

[0208] In the first stage, control branch 201 sends a control signal to open both the first switch S1 and the second switch S2, obtaining the first sampling signal Up-adc, the second sampling signal Un-adc, and the third sampling signal Ucx-adc. Based on resistor voltage division sampling, it calculates and determines the voltage Up across the positive-to-ground battery insulation resistor, the voltage Un across the negative-to-ground battery insulation resistor, and the voltage Ucx across the first capacitor Cx, where:

[0209] Up = Up - adc * (R2 + R3) / R3;

[0210] Un = Un - adc * (R4 + R6) / R6;

[0211] Ucx=Ucx-adc*(R13+R14) / R14.

[0212] In this embodiment of the invention, based on the first sampling signal Up-adc1 obtained by sampling, the voltage Up1 across the insulation resistance of the battery facing to ground in this case is determined; based on the second sampling signal Un-adc1 obtained by sampling, the voltage Un1 across the insulation resistance of the battery facing to ground in this case is determined; and based on the third sampling signal Ucx-adc1 obtained by sampling, the voltage Ucx1 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory (at any node, the sum of the inflow currents equals the sum of the outflow currents), the control branch 201 can construct the current input and output equation 1: Up1 / (Rp1 / / (R2+R3))+(Un1-Ucx1) / Rp2=Un1 / (Rn1 / / (R4+R6) / / Rn2).

[0213] It should be noted that, Figure 6 The detection circuit shown is Figure 5 The equivalent circuit diagram of the main positive relay in the off state, as shown below. Figure 6 As shown, the negative-to-ground insulation resistance Rn=Rn1 / / Rn2, then equation 1 is updated to: Up1 / (Rp1 / / (R2+R3))+(Un1-Ucx1) / Rp2=Un1 / (Rn / / (R4+R6)).

[0214] In the second stage, control branch 201 controls the first switch S1 to turn on and the second switch S2 to turn off through control signals. Based on the first sampling signal Up-adc2 obtained by sampling, the voltage Up2 across the insulation resistance of the battery facing to ground in this case is determined; based on the second sampling signal Un-adc2 obtained by sampling, the voltage Un2 across the insulation resistance of the battery facing to ground in this case is determined; and based on the third sampling signal Ucx-adc2 obtained by sampling, the voltage Ucx2 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory (at any node, the sum of the inflow currents equals the sum of the outflow currents), control branch 201 can be written as equation 2: Up2 / (Rp1 / / (R2+R3) / / R1)+(Un2-Ucx2) / Rp2=Un2 / (Rn / / (R4+R6)).

[0215] In the third stage, control branch 201 controls the first switch to be turned on and the second switch to be turned off through the control signal. Based on the first sampling signal Up-adc3 obtained by sampling, the voltage Up3 across the insulation resistance of the battery facing to ground in this case is determined; based on the second sampling signal Un-adc3 obtained by sampling, the voltage Un3 across the insulation resistance of the battery facing to ground in this case is determined; and based on the third sampling signal Ucx-adc3 obtained by sampling, the voltage Ucx3 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory (at any node, the sum of the inflow currents equals the sum of the outflow currents), control branch 201 can be set up with equation 3: Up3 / (Rp1 / / (R2+R3))+(Un3-Ucx3) / Rp2=Un3 / (Rn / / (R4+R6) / / R5).

[0216] Alternatively, control branch 201 controls both the first switch S1 and the second switch S2 to be turned on via control signals. Based on the first sampling signal Up-adc4 obtained by sampling, the voltage Up4 across the insulation resistance of the battery directly to ground is determined in this case; and based on the second sampling signal Un-adc4 obtained by sampling, the voltage Un4 across the insulation resistance of the battery negatively to ground is determined in this case; and based on the third sampling signal Ucx-adc4 obtained by sampling, the voltage Ucx4 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory, control branch 201 can obtain equation 4: Up4 / (Rp1 / / (R2+R3) / / R1)+(Un4-Ucx4) / Rp2=Un4 / (Rn / / (R4+R6) / / R5).

[0217] In this embodiment of the utility model, by solving any three of the above equations 1-4, the unknowns Rp1 (positive to ground battery insulation resistance), Rp2 (positive to ground vehicle insulation resistance), and Rn (negative to ground insulation resistance) are obtained, which are the resistance values ​​of the positive to ground insulation resistance and the negative to ground insulation resistance.

[0218] In some embodiments, such as Figure 7 As shown, for a detection circuit with a main negative relay, the BMS performs insulation resistance detection when the main negative relay is in the open state:

[0219] In the first stage, control branch 201 sends a control signal to open both the third switch S3 and the fourth switch S4, obtaining the first sampling signal Up-adc, the second sampling signal Un-adc, and the third sampling signal Ucx-adc. Based on resistor voltage division sampling, it calculates and determines the voltage Up across the positive-to-ground battery insulation resistor, the voltage Un across the negative-to-ground battery insulation resistor, and the voltage Ucx across the first capacitor Cx, where:

[0220] Up = Up - adc * (R8 + R9) / R9;

[0221] Un = Un - adc * (R10 + R12) / R12;

[0222] Ucx=Ucx-adc*(R13+R14) / R14.

[0223] In this embodiment of the invention, based on the first sampling signal Up-adc5 obtained by sampling, the voltage Up5 across the insulation resistance of the battery facing to ground in this case is determined; based on the second sampling signal Un-adc5 obtained by sampling, the voltage Un5 across the insulation resistance of the battery facing to ground in this case is determined; and based on the third sampling signal Ucx-adc5 obtained by sampling, the voltage Ucx5 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory, the control branch 201 can be represented by equation 5: Up5 / (Rp1 / / (R8+R9) / / Rp2)+(Up5-Ucx5) / Rn2=Un5 / (Rn1 / / (R10+R12)).

[0224] It should be noted that, Figure 8 The detection circuit shown is Figure 7 The equivalent circuit diagram of the main negative relay in the off state, as shown below. Figure 8 As shown, the insulation resistance to ground is Rp = Rp1 / / Rp2, then the above equation 5 can be updated to: Up1 / (Rp / / (R8+R9))+(Up1-Ucx1) / Rn2=Un1 / (Rn1 / / (R10+R12)).

[0225] In the second stage, control branch 201 controls the third switch to be turned on and the fourth switch to be turned off through the control signal. Based on the first sampling signal Up-adc6 obtained by sampling, the voltage Up6 across the insulation resistance of the battery facing to ground in this case is determined; based on the second sampling signal Un-adc6 obtained by sampling, the voltage Un6 across the insulation resistance of the battery facing to ground in this case is determined; and based on the third sampling signal Ucx-adc6 obtained by sampling, the voltage Ucx6 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory, control branch 201 can be written as equation 6: Up6 / (Rp / / (R8+R9) / / R7)+(Up6-Ucx6) / Rn2=Un6 / (Rn1 / / (R10+R12)).

[0226] In the third stage, control branch 201 controls the fourth switch to turn on and the third switch to turn off through control signals. Based on the first sampling signal Up-adc7 obtained by sampling, the voltage Up7 across the insulation resistance of the battery facing to ground in this case is determined; based on the second sampling signal Un-adc7 obtained by sampling, the voltage Un7 across the insulation resistance of the battery facing to ground in this case is determined; and based on the third sampling signal Ucx-adc7 obtained by sampling, the voltage Ucx7 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory, control branch 201 can be represented by equation 7: Up7 / (Rp / / (R8+R9))+(Un7-Ucx7) / Rn2=Un7 / (Rn1 / / (R10+R12) / / R11).

[0227] Alternatively, control branch 201 controls both the third and fourth switches to be turned on via control signals. Based on the first sampling signal Up-adc8 obtained from sampling, the voltage Up8 across the insulation resistance of the battery directly to ground is determined in this case; based on the second sampling signal Un-adc8 obtained from sampling, the voltage Un8 across the insulation resistance of the battery indirectly to ground is determined in this case; and based on the third sampling signal Ucx-adc8 obtained from sampling, the voltage Ucx8 across the first capacitor Cx is determined. Based on Kirchhoff's current law circuit theory, control branch 201 can obtain equation 8: Up8 / (Rp / / (R8+R9) / / R7)+(Un8-Ucx8) / Rn2=Un8 / (Rn1 / / (R10+R12) / / R11).

[0228] In this embodiment of the utility model, based on any three equations in Equations 5 to 8 constructed above, the values ​​of the unknowns Rp (positive to ground insulation resistance), Rn1 (negative to ground battery insulation resistance), and Rn2 (negative to ground vehicle insulation resistance) can be obtained, which are the positive to ground insulation resistance and the negative to ground insulation resistance.

[0229] Thus, in this embodiment of the invention, with the detection circuit including a single relay (a main positive relay and a main negative relay), when the main positive relay or the main negative relay is turned off, it is not affected by the voltage discharged from the outside of the relay, and the resistance value of the positive to ground insulation resistance and the resistance value of the negative to ground insulation resistance are accurately sampled and calculated, thereby improving the accuracy and reliability of insulation detection.

[0230] In another embodiment of this utility model, an electrically driven device is provided, such as... Figure 10 As shown, the electric drive device 30 includes the battery management system 20 in the aforementioned embodiments.

[0231] In this embodiment of the invention, the electric drive device 30 can be a battery-powered device containing a battery pack. Its internal battery management system 20 can monitor the connection status of the battery pack to ensure the integrity of the high-voltage circuit between battery packs. For example, the electric drive device 30 can be a new energy vehicle, ship, aircraft, etc., or a power device such as an electric vehicle, hybrid vehicle, or electric motorcycle.

[0232] It should be understood that those skilled in the art will recognize that this invention may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this invention may take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0233] It should also be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the present invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of the present invention, the sequence number of the above-described steps / processes does not imply the order of execution; the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention. The above-described embodiment numbers are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0234] It should be noted that, in this utility model, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0235] In the several embodiments provided by this utility model, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0236] The units described above as separate components may or may not be physically separate; the components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units; some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the various embodiments of this utility model, all functional units may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the integrated unit may be implemented in hardware or in a combination of hardware and software functional units.

[0237] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of protection of the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A detection circuit, characterized in that, The detection circuit includes a relay module, a first voltage divider module, a second voltage divider module, and a charge / discharge module; wherein: The battery insulation resistor is connected to the first voltage divider module, the second voltage divider module, and the battery pack respectively. The relay module is connected between the first voltage divider module and / or the second voltage divider module and the vehicle insulation resistor. The charging and discharging module is connected to the vehicle insulation resistor. The detection circuit is used to acquire at least one first sampling signal provided by the first voltage divider module, at least one second sampling signal provided by the second voltage divider module, and at least one third sampling signal provided by the charging and discharging module when the relay module is in the off state and the first voltage divider module and the second voltage divider module are in different states. The at least one first sampling signal, the at least one second sampling signal, and the at least one third sampling signal are used to determine the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance.

2. The detection circuit according to claim 1, characterized in that, The battery insulation resistance includes the positive-to-ground battery insulation resistance and the negative-to-ground battery insulation resistance; wherein: The first end of the positive-to-ground battery insulation resistor is connected to the positive terminal of the battery pack and the first end of the first voltage divider module, respectively; the second end of the positive-to-ground battery insulation resistor is connected to the second end of the first voltage divider module, the first end of the second voltage divider module, and the first end of the negative-to-ground battery insulation resistor, respectively. The second end of the negative-to-ground battery insulation resistor is connected to the negative terminal of the battery pack and the second end of the second voltage divider module, respectively.

3. The detection circuit according to claim 2, characterized in that, The relay module includes a main positive relay; wherein: The main positive relay is connected between the first voltage divider module and the vehicle insulation resistor.

4. The detection circuit according to claim 3, characterized in that, The vehicle insulation resistance includes the vehicle insulation resistance to ground and the vehicle insulation resistance to ground; wherein: The first end of the positive-to-ground vehicle insulation resistor is connected to the first end of the main positive relay and the first end of the charging and discharging module, respectively; the second end of the positive-to-ground vehicle insulation resistor is connected to the first end of the negative-to-ground vehicle insulation resistor and the ground end, respectively. The second terminal of the negative-to-ground vehicle insulation resistor is connected to the second terminal of the second voltage divider module and the second terminal of the charge / discharge module, respectively.

5. The detection circuit according to claim 4, characterized in that, The first voltage divider module includes a first resistor, a second resistor, a third resistor, and a first switch; wherein: The first end of the first resistor is connected to the first end of the insulation resistor of the battery facing ground and the first end of the second resistor, respectively; the second end of the first resistor is connected to the first end of the first switch. The first end of the second resistor is connected to the main positive relay, and the second end of the second resistor is connected to the first end of the third resistor; The second terminal of the first switch is connected to the second terminal of the third resistor, the second terminal of the insulation resistor of the battery facing ground, and the second voltage divider module, respectively. The second end of the third resistor is also connected to the second end and the ground end of the vehicle insulation resistor directly facing the ground, respectively. The sampling point between the second resistor and the third resistor is used to acquire the first sampling signal.

6. The detection circuit according to claim 4, characterized in that, The second voltage divider module includes a fourth resistor, a fifth resistor, a sixth resistor, and a second switch; wherein: The first end of the fourth resistor is connected to the first end of the second switch, the ground terminal, and the second end of the first voltage divider module, respectively; the second end of the fourth resistor is connected to the first end of the sixth resistor. The first terminal of the second switch is connected to the first terminal of the negative-to-ground battery insulation resistor, and the second terminal of the second switch is connected to the first terminal of the fifth resistor; The second end of the fifth resistor is connected to the second end of the negative-to-ground battery insulation resistor and the second end of the sixth resistor, respectively. The second end of the sixth resistor is also connected to the second end of the negative-to-ground vehicle insulation resistor. The sampling point between the fourth resistor and the sixth resistor is used to acquire the second sampling signal.

7. The detection circuit according to claim 2, characterized in that, The relay module includes a main negative relay; wherein: The main negative relay is connected between the second voltage divider module and the vehicle insulation resistor.

8. The detection circuit according to claim 7, characterized in that, The vehicle insulation resistance includes the vehicle insulation resistance to ground and the vehicle insulation resistance to ground; wherein: The first end of the positive-to-ground vehicle insulation resistor is connected to the first end of the first voltage divider module and the first end of the charging and discharging module, and the second end of the positive-to-ground vehicle insulation resistor is connected to the first end of the negative-to-ground vehicle insulation resistor and the ground end, respectively. The second terminal of the negative-to-ground vehicle insulation resistance is connected to the second terminal of the main negative relay and the charging / discharging module, respectively.

9. The detection circuit according to claim 8, characterized in that, The first voltage divider module includes a seventh resistor, an eighth resistor, a ninth resistor, and a third switch; wherein: The first end of the seventh resistor is connected to the first end of the insulation resistor of the battery facing to ground and the first end of the eighth resistor, respectively; the second end of the seventh resistor is connected to the first end of the third switch. The first end of the eighth resistor is connected to the first end of the vehicle insulation resistor facing ground, and the second end of the eighth resistor is connected to the first end of the ninth resistor. The second terminal of the third switch is connected to the second terminal of the ninth resistor, the second terminal of the insulation resistor of the battery facing ground, and the second voltage divider module, respectively. The second end of the ninth resistor is also connected to the second end and the ground end of the vehicle insulation resistor directly facing the ground, respectively. The sampling point between the eighth resistor and the ninth resistor is used to acquire the first sampling signal.

10. The detection circuit according to claim 8, characterized in that, The second voltage divider module includes a tenth resistor, an eleventh resistor, a twelfth resistor, and a fourth switch; wherein: The first end of the tenth resistor is connected to the first end of the fourth switch, the ground terminal, and the second end of the first voltage divider module, respectively; the second end of the tenth resistor is connected to the first end of the twelfth resistor. The first terminal of the fourth switch is connected to the first terminal of the negative-to-ground battery insulation resistor, and the second terminal of the fourth switch is connected to the first terminal of the eleventh resistor. The second end of the eleventh resistor is connected to the second end of the insulation resistor of the negative-to-ground battery and the second end of the twelfth resistor, respectively. The second end of the twelfth resistor is also connected to the main negative relay. The sampling point between the tenth resistor and the twelfth resistor is used to acquire the second sampling signal.

11. The detection circuit according to any one of claims 1-10, characterized in that, The charging and discharging module includes a first capacitor, a thirteenth resistor, and a fourteenth resistor; wherein: The first terminal of the first capacitor is connected to the first terminal of the vehicle insulation resistor to ground and the first terminal of the thirteenth resistor, respectively; the second terminal of the first capacitor is connected to the second terminal of the vehicle insulation resistor to ground and the second terminal of the fourteenth resistor, respectively. The second end of the thirteenth resistor is connected to the first end of the fourteenth resistor; The sampling point between the thirteenth resistor and the fourteenth resistor is used to acquire the third sampling signal.

12. The detection circuit according to claim 11, characterized in that, The detection circuit further includes a load resistor; wherein; The first end of the load resistor is connected to the first end of the positive ground vehicle insulation resistor and the first end of the first capacitor, respectively. The second end of the load resistor is connected to the second end of the negative ground vehicle insulation resistor and the second end of the first capacitor, respectively.

13. A battery management system, characterized in that, The battery management system includes a control branch and a detection circuit as described in any one of claims 1-12, wherein the control branch is connected to the detection circuit; wherein: The control branch is used to determine the resistance value of the positive-to-ground insulation resistance and the resistance value of the negative-to-ground insulation resistance based on the first sampling signal, the second sampling signal and the third sampling signal obtained by the detection circuit.

14. An electrically driven device, characterized in that, The electric drive device includes the battery management system as described in claim 13.

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