Method, controller and system for handling insulation faults in battery operating systems

Abstract

The present application relates to a method of handling an insulation fault in a battery operated high voltage electrical system for a propulsion vehicle, the system comprising a plurality of propulsion battery packs (12) and at least one motor (16) connected to the plurality of propulsion battery packs, the method comprising the steps of: when in operation, performing an insulation measurement of the system; opening all propulsion battery packs if an insulation fault is detected in the system; measuring the insulation resistance between the positive electrode side of each battery pack and the ground, and measuring the insulation resistance between the negative electrode side of each battery pack and the ground; the battery pack is reconnected if the measured resistance in the battery pack is above a predetermined value, and the battery pack is held off if the measured resistance in the battery pack is below the predetermined value. The application also relates to a controller for a vehicle and a high-voltage electrical system.

Description

Technical Field

[0001] This application relates to insulation faults that may occur in battery operating systems, such as in electric propulsion vehicles, and how such faults can be handled. Background Art

[0002] Vehicles powered and propelled by electricity are developing rapidly, whether as hybrid vehicles with an electric motor and an internal combustion engine or as fully electric propulsion vehicles. For larger and heavier electric propulsion vehicles, such as trucks and buses, it is most common to require several battery packs in order to provide the required amount of energy for driving longer distances.

[0003] In the case of serious faults in these systems due to the large amount of energy in the battery packs and the high voltage used in the high-voltage electrical systems, this requires new safety measures. One type of serious fault that can occur is an insulation fault in the vehicle during driving or at least when the battery packs are connected and the high-voltage system is operating.

[0004] The monitoring system of the vehicle can detect such an insulation fault and warn the driver of the vehicle that there is a fault in the high-voltage electrical system. However, the monitoring system cannot detect where in the electrical system the fault is located. The fault can be a vehicle / external fault, such as a short circuit in the high-voltage circuit, or an internal battery fault, such as a coolant leak or a short circuit between the batteries within a battery pack. Since all battery packs are connected to the high-voltage electrical system when such an insulation fault occurs, it is impossible to distinguish an internal fault. When such a fault occurs, the system alerts the driver.

[0005] In order to detect an internal fault, the vehicle must be stopped and all battery packs must be disconnected from the system in order to measure and detect an internal fault in a specific battery pack. This is done by the driver stopping the vehicle and manually turning off the power from the electrical system and then turning it on again, which triggers a diagnostic test and measurement of the battery packs. If an internal insulation fault is found in a certain battery pack, that battery pack is disconnected while the remaining fully functional battery packs are reconnected, after which the vehicle can be operated again.

[0006] This is a disadvantage because the driver must find a place to stop quite quickly, which can be difficult, for example, when driving on a highway, and there is a risk that the stop may cause traffic problems. Therefore, this leads to an increased pressure on the driver to operate the vehicle so as to minimize traffic problems while avoiding an increased risk of faults due to continued driving.

[0007] Therefore, further measures regarding the handling of insulation faults in electric propulsion vehicles are needed. Summary of the Invention

[0008] In the description, the term vehicle is used. In this context, a vehicle shall be understood as any flying vehicle that can be moved or propelled by an electric motor powered by a plurality of battery packs. Thus, cars, trucks, buses, trains, boats, ships, etc. are included in the term vehicle.

[0009] According to one aspect, a method for handling insulation faults in a high-voltage electrical system that operates batteries for propelling a vehicle is provided, wherein the method is executed by a controller. The system may include a plurality of propulsion battery packs and at least one electric motor connected to the plurality of propulsion battery packs. The method may include performing an insulation measurement of the system when in operation. If an insulation fault is detected in the system, all propulsion battery packs are disconnected, the insulation resistance between the positive side of each battery pack and ground is measured, and the insulation resistance between the negative side of each battery pack and ground is measured. If the measured resistance in a battery pack is higher than a predetermined value, the battery pack is reconnected, and if the measured resistance in a battery pack is lower than the predetermined value, the battery pack is kept disconnected.

[0010] This has the advantage that the method can be performed during the operation of the vehicle, i.e., during driving, and the vehicle does not have to stop in order to diagnose a severe insulation fault. Of course, the operation can be performed when the vehicle is stationary but activated or when in operation when an insulation fault occurs. Thus, the method is performed automatically without requiring interaction from the driver.

[0011] Preferably, when the system is in operation, the insulation measurement of the high-voltage electrical system can be performed periodically. Thus, any severe insulation fault that occurs will be detected and handled quickly. The method may also include the steps of providing information that at least one battery pack has been disconnected from the system and preferably also providing this information to the operator of the vehicle. This provides the driver of the vehicle with what has occurred and has been handled.

[0012] The predetermined value may be based on an insulation resistance value higher than about 100 ohms / volt, as specified in Regulation No. 100 of the United Nations Economic Commission for Europe (UNECE), which insulation resistance value is considered safe for operation.

[0013] In addition, a computer program product including instructions is provided, which instructions cause the computer to perform the method when the program is executed by the computer. Moreover, a computer-readable storage medium including instructions is provided, which instructions cause the computer to perform the method when executed by the computer.

[0014] According to another aspect, there is provided a controller for handling insulation faults in a high-voltage electrical system for battery-operated propulsion of a vehicle, wherein the system may include: a plurality of propulsion battery packs, each propulsion battery pack being provided with a contactor, each battery pack being provided with a component for measuring insulation resistance connected to the controller; and at least one electric motor connected to the plurality of battery packs. If the controller detects an insulation fault in the system, the contactors are activated to disconnect all propulsion battery packs. Further, information on the insulation resistance between the positive side of each battery pack and ground and the insulation resistance between the negative side of each battery pack and ground can be obtained from the insulation resistance measuring component, and if the obtained resistance value in the battery pack is higher than a predetermined value, the contactor of the battery pack is activated to reconnect to the system, and if the obtained resistance value in the battery pack is lower than the predetermined value, the battery pack is kept disconnected from the system.

[0015] Further, there is provided a high-voltage electrical system for propulsion of a vehicle, the system including: a plurality of propulsion battery packs, each battery pack being provided with a contactor, each battery pack being provided with a component for measuring insulation resistance; at least one electric motor connected to the plurality of propulsion battery packs; and a controller.

[0016] These and other aspects and advantages of the present invention will become apparent from the following detailed description of the invention and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the following detailed description of the invention, reference will be made to the accompanying drawings, in which

[0018] Figure 1 an electric propulsion vehicle is schematically shown,

[0019] Figure 2 connected to is schematically shown

[0020] the battery packs of the high-voltage electrical system included in the vehicle, and

[0021] Figure 3 is a flowchart of a method for handling insulation faults. DETAILED DESCRIPTION

[0022] Examples of solutions according to the present application will be described in connection with use in Figure 1 a heavy-duty land-based vehicle 10 (such as a bus or a truck).

[0023] The vehicle is provided with a plurality of battery packs 12. Each battery pack includes a plurality of battery cells 13 interconnected to provide a certain output voltage. The construction and configuration of the battery packs are well known and will not be described in detail. The battery packs are connected to a high-voltage electrical system 14 including electrical wires. One or several electric motors 16 can be connected to the high-voltage electrical system for propelling the vehicle. Other electrical devices can also be connected to the high-voltage electrical system 14.

[0024] Each battery pack is provided with a contactor 18 ( Figure 2 ), for connecting each battery pack to the high-voltage electrical system 14 and disconnecting each battery pack from the high-voltage electrical system. It should be understood that in this context, the term contactor can include several different solutions capable of connecting and disconnecting the battery pack, such as mechanical switches, electronic circuits, power electronic devices or combinations thereof. The contactor 18 can be activated by a controller 20, which is part of the monitoring and supervision system of the high-voltage electrical system 14. In this regard, the contactor may of course be arranged outside the battery pack, which can form part of the connection means between the battery pack and the wiring of the electrical system. Each battery pack 12 is also provided with different types of sensors and measuring devices for monitoring the state of the battery pack. One such feature is a member or device 22 for measuring the insulation resistance in the battery pack. As Figure 2 seen, the measuring device 22 is arranged to measure the insulation resistance R between the positive side of the battery pack and the ground i+b , and the resistance R between the negative side of the battery pack and the ground i-b . In this application of the vehicle, the ground can be the chassis of the vehicle.

[0025] The solution according to the present application is intended to operate as seen below in Figure 3 . When the vehicle is parked and stationary, all battery packs 12 are disconnected from the high-voltage electrical system. When the vehicle is activated for operation, the driver operates the appropriate start feature. The controller can perform an initial diagnostic test of the electrical system and the battery packs. Then, the controller activates the contactor to connect the battery packs to the high-voltage electrical system. Now, the vehicle can be operated and propelled by the electric motor or machines powered by the battery packs. During operation, the controller continuously / periodically monitors the high-voltage electrical system, including measuring the insulation of the electrical system.

[0026] If a severe insulation fault occurs during the operation of the vehicle, such a situation is detected by the controller 20. However, since the measurement is performed on the entire system with all battery packs connected, i.e., the insulation resistance R of the battery packs ib and the insulation resistance R of the high-voltage electrical system of the vehicle iv , it is not possible to obtain information whether the insulation fault is internal (i.e., in one or more battery packs) or external (i.e., in the high-voltage electrical system).

[0027] To detect where the insulation fault lies, the controller 20 temporarily disconnects all battery packs via the contactor 18. During the disconnection, insulation resistance measurements are performed on all battery packs. If one or more battery packs are found to have an insulation resistance below a preset value, this indicates a serious insulation fault in that battery pack or those battery packs.

[0028] After the measurement, the controller reconnects the battery packs with an insulation resistance higher than the predetermined value. On the other hand, the battery packs that have been found to have an insulation resistance below the predetermined value are blocked and remain disconnected. The vehicle can continue to operate, but with fewer battery packs now connected. Since the measurement of the insulation resistance in the battery packs is performed within a short time period (about 5 seconds), and thus the battery packs are disconnected for a short time, this operation can be performed while the vehicle is moving, and due to the inertia of a heavy vehicle such as a truck or a bus at a higher speed, the speed of the vehicle is not seriously affected during the disconnection and reconnection operations of the battery packs. This has the advantage that the vehicle does not have to stop to diagnose a serious insulation fault. In this regard, of course, the operation can be performed when the vehicle is stationary but activated or in operation when the insulation fault occurs.

[0029] The predetermined insulation value can depend on several factors and is set according to the desired level of safe operation. As an indication, Regulation No. 100 of the UNECE states that an insulation resistance value higher than about 100 ohms / volt is considered safe for the operation of the system.

[0030] If the controller detects an insulation fault, this is preferably indicated to the driver of the vehicle in a suitable manner so that he or she is aware that an insulation fault has occurred, has been processed and can continue driving. However, if one or more battery packs have been disconnected, the driver should preferably be informed that the available power from the battery has decreased.

[0031] It should be understood that the embodiments described above and shown in the drawings are only considered as non-limiting examples of the present application and can be modified in many ways within the scope of the patent claims.

Claims

1. A method for handling insulation faults in a high-voltage electrical system for battery-operated propulsion of a vehicle, wherein the method is executed by a controller (20), the system comprising a plurality of propulsion battery packs (12) and at least one electric motor (16) connected to the plurality of propulsion battery packs, the method comprising the steps of: - During operation, perform insulation measurements on the system, - If an insulation fault is detected in the system, then - Disconnect all propulsion battery packs; - Measure the insulation resistance between the positive side of each battery pack and ground, and measure the insulation resistance between the negative side of each battery pack and ground; - If the measured insulation resistance in a battery pack is higher than a predetermined value, reconnect the battery pack, and if the measured insulation resistance in a battery pack is lower than the predetermined value, keep the battery pack disconnected.

2. The method according to claim 1, wherein the insulation measurements on the high-voltage electrical system are performed periodically when the system is in operation.

3. The method according to any one of the preceding claims, further comprising the step of providing information that at least one battery pack is disconnected from the system.

4. The method according to claim 3, wherein the information is provided to the operator of the vehicle.

5. The method according to any one of the preceding claims, wherein the predetermined value is based on an insulation resistance value of higher than about 100 ohms / volt, which is considered safe for operation.

6. A computer program product comprising instructions that, when the program is executed by a computer, cause the computer to perform the method according to any one of claims 1-5.

7. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the method according to any one of claims 1-5.

8. A controller (20) for handling insulation faults in a battery-operated high-voltage electrical system (12, 14) for propelling a vehicle (10), the high-voltage electrical system comprising: A plurality of propulsion battery packs (12), each propulsion battery pack being provided with a contactor (18), each battery pack being provided with means (22) for measuring insulation resistance connected to the controller; and at least one electric motor (16) connected to the plurality of battery packs, - The controller (20) is configured to verify that the system is in operation, - If the controller (20) detects an insulation fault in the system during operation, then - Activate the contactors (18) to disconnect all propulsion battery packs (12); - Obtain information from the insulation resistance measuring means (22) about the insulation resistance between the positive side of each battery pack and ground and the insulation resistance between the negative side of each battery pack and ground; - If the obtained insulation resistance value in a battery pack is higher than a predetermined value, activate the contactor (18) of that battery pack to reconnect to the system (14), and if the obtained insulation resistance value in a battery pack is lower than the predetermined value, keep the battery pack disconnected from the system.

9. A high-voltage electrical system for propelling a vehicle, the system comprising: A plurality of propulsion battery packs (12), each battery pack being provided with a contactor (18), each battery pack being provided with means (22) for measuring insulation resistance; at least one electric motor (16) connected to the plurality of propulsion battery packs; and a controller according to claim 8.

10. A vehicle (10), the vehicle comprising the system according to claim 10.

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