Battery pack selection for DC bus pre-charging

Abstract

The present disclosure provides a system and method for selecting a battery pack for precharging the high-voltage DC bus of an electric vehicle. A looping structure is disclosed that prevents repeated selection of a battery pack to prevent resistor burnout in the battery pack due to rapid subsequent precharging events. The provided system and method include a simple solution that is scalable to systems with any number of battery packs, does not require any additional hardware, and is an inexpensive technique for protecting expensive components of electric vehicles.

Description

Technical Field

[0001] The present disclosure relates to pre-charging of a DC bus in an electric or hybrid vehicle. More particularly, the present disclosure relates to systems and methods for selecting a battery pack for pre-charging a DC bus of an electric or hybrid vehicle. Background Art

[0002] In vehicles with multiple battery packs connected in a parallel configuration, precharging the high-voltage DC bus must be completed by at least one battery pack before any battery pack in the configuration can close its contactors to allow vehicle operation. Each battery pack includes a precharge circuit that includes resistors that dissipate power through heat. As a result, overuse of the resistors can cause the overused resistor to burn out.

[0003] Because each battery pack includes a single pre-charge circuit, repeatedly pre-charging the high-voltage DC bus using the same battery pack in rapid succession will damage the resistors, resulting in an inoperable battery pack that is expensive to replace and complicated to repair. This problem is particularly prevalent and significant in electric vehicles, especially where operator behavior determines how often pre-charging the high-voltage DC bus will occur. For example, if the contactors in each battery pack must be closed at each key-on to operate the vehicle, then pre-charging the high-voltage DC bus must occur at each key-on. To avoid premature resistor burnout and battery pack failure, solutions have been proposed that include additional hardware or software or hardware add-ons for each battery pack. However, these solutions are not ideal and need improvement. Summary of the Invention

[0004] The present disclosure provides a system and method for selecting a battery pack for precharging the high-voltage DC bus of an electric vehicle. A looping structure is disclosed that prevents repeated selection of a battery pack to prevent resistor burnout in the battery pack due to rapid subsequent precharging events. The provided system and method include a simple solution that is scalable to systems with any number of battery packs, does not require any additional hardware, and is an inexpensive technique for protecting expensive components of electric vehicles.

[0005] In an embodiment of the present disclosure, a system for selecting battery packs for a vehicle is disclosed. The system includes: a plurality of battery packs connected in parallel; a controller operably coupled to the plurality of battery packs; a memory operably coupled to the controller; and a DC bus operably coupled to the plurality of battery packs, such that at least one of the plurality of battery packs is configured to selectively precharge the DC bus during a DC bus precharge event. The controller is configured to assemble a queue for precharging the DC bus based on usage of the plurality of battery packs and save the queue to the memory for subsequent use.

[0006] The head of the queue may include a battery pack having a lowest state of charge compared to the remaining battery packs in the plurality of battery packs. The controller may be configured to receive the saved queue from the memory for use in a subsequent DC bus pre-charge event. The controller may be configured to receive a health index of any of the plurality of battery packs to determine whether any of the plurality of battery packs is faulty. After each DC bus pre-charge event, a different queue may be assembled relative to the queue used immediately before.

[0007] In another embodiment of the present disclosure, a method for selecting a battery pack for a vehicle is disclosed, the method comprising: retrieving a queue from a memory; requesting identification of a battery pack at the head of the queue; instructing the identified battery pack to complete pre-charging of a DC bus; and pushing the identified battery pack to the tail of the queue to create a second queue.

[0008] The method may further include determining whether precharging the DC bus is successfully completed. When precharging the DC bus is not successfully completed, the method may further include requesting a second identification of a second battery pack located at the head of a second queue; instructing the second battery pack to complete precharging the DC bus; determining whether precharging the DC bus is successfully completed; pushing the second battery pack to the tail of the second queue to create a third queue; and repeating until precharging the DC bus is successfully completed. When precharging the DC bus is successfully completed, the method may further include initiating operation of the vehicle.

[0009] The method may further include checking the health index of the identified battery pack before instructing the identified battery pack to complete pre-charging of the DC bus to determine whether the identified battery pack is faulty. When the battery pack is faulty, the method may further include requesting a second identification of a second battery pack located at the head of the second queue; checking the health index of the second battery pack; and determining whether the second battery pack is faulty. When the second battery pack is faulty, the method may further include pushing the second battery pack to the tail of the second queue to create a third queue, and repeating until an operable battery pack is identified. When the identified battery pack is operable, the method may further include initiating vehicle operation after pre-charging of the DC bus is completed.

[0010] In yet another embodiment of the present disclosure, a method for selecting a battery pack for a vehicle is disclosed, the method comprising: identifying a battery pack having a lowest state of charge compared to the remaining battery packs among a plurality of battery packs; instructing the identified battery pack to precharge a DC bus; storing the identified battery pack in a memory; creating a queue, wherein the identified battery pack is at the head of the queue; and pushing the identified battery pack to the tail of the queue to create a subsequent queue. The method may also include checking a health index of the identified battery pack to determine whether the identified battery pack is faulty.

[0011] Other features and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed description of exemplary embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The detailed description of the drawings makes specific reference to the accompanying drawings, in which:

[0013] Figure 1 An exemplary system of the present disclosure for precharging a high-voltage DC bus is shown, the system comprising a plurality of battery packs connected in parallel, a controller, and a memory;

[0014] Figure 2 An exemplary method of the present disclosure for selecting a battery pack from a plurality of battery packs connected in parallel to complete pre-charging of a high-voltage DC bus during a first vehicle operation start by a user is shown;

[0015] Figure 3 An exemplary queue for selecting a battery pack from a plurality of battery packs connected in parallel is shown;

[0016] Figure 4A An exemplary method of the present disclosure for selecting a battery pack from a plurality of battery packs connected in parallel to complete pre-charging of a high-voltage DC bus during subsequent vehicle operation initiation by a user is shown;

[0017] Figure 4B Shown Figure 4A Another embodiment of the exemplary method of;

[0018] Figure 5A Another exemplary method of the present disclosure for selecting a battery pack from a plurality of battery packs connected in parallel to complete pre-charging of a high-voltage DC bus during subsequent vehicle operation initiation by a user is illustrated, wherein a controller checks a health index of each battery pack in the plurality of battery packs;

[0019] Figure 5B Shown Figure 5B Another embodiment of the exemplary method of .

[0020] In the several views, corresponding reference numerals indicate corresponding parts. Although the drawings show embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale, and certain features may be exaggerated to better illustrate and explain the present disclosure. The examples set forth herein illustrate embodiments of the present invention, and such examples should not be construed as limiting the scope of the present invention in any way. DETAILED DESCRIPTION

[0021] First reference Figure 1 , discloses a system 100 for a vehicle. The system 100 includes a battery master controller 102, a non-volatile memory 104, and a plurality of battery packs 106, wherein the battery packs 106 are schematically connected in a parallel configuration. Although the illustrated embodiment discloses six battery packs 106, the methods and systems described herein are scalable and can be applied to vehicles having any number of battery packs 106. The battery packs 106 can have different levels of state of charge percentage. For example, as shown, battery pack 106a can have a lower state of charge percentage than battery pack 106b. Any battery pack 106 can have a lower, higher, or equal state of charge percentage relative to any other battery pack 106.

[0022] The battery packs 106 are operably connected to the battery master controller 102 and, optionally, to the high-voltage DC bus 108, wherein the battery master controller 102 can communicate with each respective battery pack 106 to initiate pre-charging of the DC bus 108 using the selected battery pack 106, as further discussed herein. Once pre-charging of the high-voltage DC bus 108 is complete, the battery master controller 102 can also communicate with each respective battery pack 106 to control the closing of the contactors of the battery pack 106 for operation of the vehicle. The battery master controller 102 is also operably connected to the memory 104 to store pre-charging events, as further discussed herein.

[0023] Now refer to Figure 2 , given that Figure 1 , a method 200 for initiating a first DC bus pre-charge event is disclosed. At block 202, a user initiates operation of a vehicle. The user may initiate the pre-charge event using any method known in the art for initiating operation of a vehicle. For example, the user may initiate the pre-charge event using a switch, a button, a push-to-on using a standard key, a remote start mechanism, use of a smart device application, use of a smart assistant, Bluetooth, a key fob, fingerprint recognition, a digital keypad, voice activation, an Internet of Things application, or other mechanisms. Before operation of the vehicle can occur, the DC bus 108 must be pre-charged using one of the plurality of battery packs 106.

[0024] After user initiation at block 202, the controller 102 identifies the battery pack 106 having the lowest state of charge percentage at block 204. For example, referring briefly to Figure 1 , the controller 102 selects the battery pack 106a because the battery pack 106a has the lowest state of charge percentage among the battery packs 106. Referring again to Figure 2 , considering Figure 1 , the controller 102 then sends an instruction to the selected battery pack 106a at block 206 to precharge the DC bus 108 during the DC bus precharge event indicated at block 208. At any time after selecting the battery pack 106 at block 204, the controller 102 stores the identity of the battery pack 106a in the memory 104 to track the completion of the precharge event at block 210. At block 212, at any time after selecting the battery pack 106 at block 204, the controller 102 additionally creates the queue 302 ( Figure 3 ), as shown in block 212, the queue 302 is stored in the memory 104. Once the pre-charge event is complete, vehicle operation begins at block 214. Ideally, at block 214, the contactors of the remaining battery packs 106 are closed to allow full vehicle operation.

[0025] However, such contactors are closed only when the controller 102 determines that the remaining battery packs 106 are operational, as discussed further herein. In some cases, the controller 102 may determine that any number of battery packs 106 less than the remaining battery packs 106 are inoperable. If any battery pack 106 is deemed inoperable, only the contactors of the operational battery packs 106 are closed for vehicle operation. In the event that not all battery packs 106 are operational, the vehicle operates at a performance percentage corresponding to the percentage of operational battery packs 106.

[0026] Figure 3 A loop structure 300 is shown, comprising the mentioned queue 302 and additional queues 304, 306 generated by user-initiated recurring instances. Figures 1 to 3After the controller 102 selects the battery pack 106 with the lowest state of charge percentage (i.e., battery pack 106a) at block 204 of method 200, the controller 102 generates the queue 302 as described above. Because battery pack 106a is the first selected battery pack, battery pack 106a is initially located at the head 308 of the queue 302. When precharging the DC bus 108, the controller 102 instructs the memory 104 to move battery pack 106a to the tail 310 of the queue, as shown in the queue 304, to avoid immediate reuse of battery pack 106a at the next user start-up. For example, if the memory 104 stores the queue 304 for use at the next user start-up, the next user start-up will cause the controller 102 to instruct battery pack 106b to precharge the DC bus. When precharging the DC bus 108, the controller 102 instructs the memory to move the battery pack 106b to the tail 310 of the queue, as shown in the queue 306, to avoid immediate reuse of the battery pack 106b upon the next user start-up. The controller 102 continues to instruct the battery pack 106 at the head 308 of the queue in this manner until all battery packs 106 have been used for the DC bus precharge event. At this time, the queue is restarted and the battery pack 106a is selected again.

[0027] Now refer to Figure 4A , considering Figure 1 and Figure 3 A method 400 is provided for Figure 2 After the initial DC bus pre-charge event method 200 completes the subsequent DC bus pre-charge event. In other words, method 200 is used for the first user start of the vehicle, that is, the first vehicle use, the first vehicle use after a system reset, the first vehicle use after a component of the system has been replaced, or any other instance in which the queue is not saved to memory. After the completion of method 200, subsequent user-initiated events cause Figure 4A The method 400 is initiated until circumstances require a system reset or other events dictate the use of the method 200 .

[0028] When a user initiates operation of the vehicle, the method 400 begins at block 402. User initiation can occur in any of the ways discussed herein with reference to the method 200. Following the user initiation at block 402, the controller 102 retrieves a queue (i.e., any one of the queues 302, 304, 306 or another subsequent queue) from the memory 104 at block 404. Block 406 also requests identification of the battery pack 106 at the head 308 of the queue. Once the appropriate battery pack 106 is identified at block 404, the controller 102 instructs the corresponding battery pack 106 to complete pre-charging the DC bus 108 at block 408. After a predetermined period of time after which the pre-charging event should complete, the controller 102 determines, at block 410, whether the pre-charging of the DC bus 108 has completed.

[0029] If the pre-charge event has been completed at box 410, the battery pack 106 used during the pre-charge event is pushed to the tail 310 of the queue at box 412, and the resulting queue is saved to the memory 104 at box 416. If the pre-charge event has not been completed at box 410, a pre-charge error occurs at box 414 and the faulty battery pack 106 is pushed to the tail 310 of the queue. At box 416, the resulting queue is saved to the memory 104, and the method 400 restarts at box 404 until the pre-charge event is successfully completed. Once the pre-charge event is successfully completed, the contactors of the remaining operational battery packs 106 are closed at box 418 to allow vehicle operation, as described above.

[0030] In some embodiments, as Figure 4B As shown, method 400b can be used. Method 400b is substantially the same as Figure 4A The method 400 shown is the same as that shown in Figure 400b, except for the exceptions described herein. In method 400b, if the pre-charge event has not yet been completed at block 410, the processor 102 can immediately retrieve the identification of the next battery pack 106 at block 406b, which simultaneously pushes the faulty battery pack 106 to the tail 310 of the queue, as shown at block 414. Method 400b is repeated until the pre-charge event is successfully completed at block 410. Once the pre-charge event is successfully completed, the battery pack 106 used during the pre-charge event is pushed to the tail 310 of the queue at block 412, and the resulting queue is saved to memory at block 416. The contactors of the remaining operable battery packs 106 are closed to allow vehicle operation at block 418, as described above. The use of method 400b can produce higher efficiency when pre-charging the vehicle's DC bus.

[0031] In some embodiments, the controller 102 can proactively identify any battery pack issues before initiating a pre-charge event to avoid pre-charge failure. Figure 5A , considering Figure 1 and Figure 3 A method 500 is provided for Figure 2 The method 200 completes subsequent DC bus pre-charge events after the initial DC bus pre-charge event, wherein the controller 102 checks the battery pack health index of the selected battery pack 106 before initiating pre-charging of the DC bus.

[0032] Method 500 begins with a user initiation at block 502, which is similar to user initiation 402 of method 400 and user initiation 202 of method 200. At block 504, controller 102 retrieves a precharge queue (i.e., any of queues 302, 304, 306 or another subsequent queue) from memory 104 and further requests identification of the battery pack 106 at the head 308 of the queue. Controller 102 then checks the health index of the identified battery pack 106 at block 506. If it is determined at block 508 that the identified battery pack 106 is faulty, the identified battery pack 106 is pushed to the tail 310 of the queue at block 510, resulting in a subsequent queue that is saved to memory 104 at block 516. Method 500 then restarts at block 504 until the precharge event is successfully completed, as further described herein.

[0033] If it is determined at block 508 that the identified battery pack 106 is not faulted, the controller 102 instructs the identified battery pack 106 to complete pre-charging of the DC bus at block 512. Then, at block 514, the battery pack 106 is pushed to the tail 310 of the queue, resulting in a subsequent queue that is saved to the memory 104 at block 516. Once the pre-charging event is successfully completed, the contactors of the remaining operational battery packs 106 are closed to allow vehicle operation at block 518, as described above.

[0034] In some embodiments, as Figure 5B As shown, method 500b may be used. Method 500b is substantially the same as Figure 5A The method 500 shown is identical to the method 500 shown, except for the exceptions described herein. In method 500b, if a battery pack has been identified as faulty at block 508, the processor 102 may immediately retrieve the identification of the next battery pack 106 at block 505b, simultaneously pushing the faulty battery pack 106 to the tail 310 of the queue, as shown at block 510. Method 500b is repeated until an operable battery pack 106 is identified at block 508. Once an operable battery pack is identified, the remainder of method 500b follows the same steps as described above for method 500.

[0035] While the invention has been described with reference to various specific embodiments, it will be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Therefore, the invention is not limited to the embodiments described, but will have the full scope defined by the language of the appended claims.

Claims

1. A system for selecting a battery pack for a vehicle, the system comprising: a plurality of battery packs connected in parallel with each other; a controller operably coupled to the plurality of battery packs; a memory operatively coupled to the controller; as well as a DC bus operatively coupled to the plurality of battery packs such that at least one of the plurality of battery packs is configured to selectively pre-charge the DC bus during a DC bus pre-charge event; The controller is configured to assemble a queue to precharge the DC bus according to usage of the plurality of battery packs, and the queue is saved to the memory for subsequent precharging of the DC bus during a subsequent DC bus precharging event.

2. The system according to claim 1, wherein: The head of the queue includes a battery pack of the plurality of battery packs having a lowest state of charge compared to the remaining battery packs.

3. The system according to claim 1, wherein: The controller is configured to receive the saved queue from the memory for the subsequent DC bus pre-charge event.

4. The system according to claim 1, wherein: The controller is configured to receive a health index of any one of the plurality of battery packs to determine whether any one of the plurality of battery packs is faulty.

5. The system according to claim 1, wherein After each DC bus pre-charge event, a different queue is assembled relative to the queue used immediately before.

6. A method for selecting a battery pack for a vehicle, the method being implemented by the system according to any one of claims 1 to 5, the method comprising: Retrieve the queue from storage; requesting identification of the battery pack at the head of the queue; Instructing the identified battery pack to complete pre-charging of the DC bus; pushing the identified battery pack to the end of the queue to create a second queue; as well as The second queue is saved to the memory.

7. The method according to claim 6, further comprising: A determination is made as to whether pre-charging of the DC bus is successfully completed.

8. The method according to claim 7, wherein: If precharging of the DC bus is not successfully completed, the method further comprises: retrieving the second queue from the memory; requesting a second identification of a second battery pack at the head of the second queue; instructing the second battery pack to complete pre-charging of the DC bus; determining whether precharging of the DC bus is successfully completed; pushing the second battery pack to the end of the second queue to create a third queue; saving the third queue to memory; and Repeat until the pre-charging of the DC bus is successfully completed.

9. The method according to claim 7, wherein: The pre-charging of the DC bus is successfully completed, and the method further includes: starting operation of the vehicle.

10. The method according to claim 6, further comprising: A health index of the identified battery pack is checked to determine whether the identified battery pack is faulty before instructing the identified battery pack to complete pre-charging of the DC bus.

11. The method according to claim 10, wherein: The identified battery pack is faulty, the method further comprising: requesting a second identification of a second battery pack at the head of the second queue; checking a health index of the second battery pack; and It is determined whether the second battery pack is faulty.

12. The method according to claim 11, wherein The second battery pack is faulty, the method further comprising: pushing the second battery pack to the end of the second queue to create a third queue, and repeating until an operable battery pack is identified.

13. The method according to claim 10, wherein: The identified battery pack is operable, the method further comprising initiating vehicle operation after the pre-charging of the DC bus is completed.

14. A method for selecting a battery pack for a vehicle, the method being implemented by the system according to any one of claims 1 to 5, the method comprising: identifying a battery pack of the plurality of battery packs having a lowest state of charge compared to the remaining battery packs; instructing the identified battery pack to pre-charge the DC bus; storing the identified battery pack in a memory; creating a queue, wherein the identified battery pack is at the head of the queue; as well as The identified battery pack is pushed to the end of the queue to create a subsequent queue.

15. The method according to claim 14, further comprising: A health index of the identified battery pack is checked to determine whether the identified battery pack is faulty.

16. The method according to claim 14, further comprising: A second queue is retrieved from memory for subsequent pre-charging of the DC bus.

17. A controller of a vehicle operatively coupled to a plurality of battery packs, the controller being used in the system according to any one of claims 1 to 5, the controller being configured to: assembling a fleet based on usage of the plurality of battery packs; identifying a battery pack at the head of the queue; Instructing the identified battery pack to complete pre-charging of the DC bus; as well as The identified battery pack is pushed to the end of the queue to create a second queue.

18. The controller according to claim 17, wherein: The controller is further configured to determine whether pre-charging of the DC bus is successfully completed.

19. The controller according to claim 18, wherein: The pre-charging of the DC bus is unsuccessfully completed, and the controller is further configured to identify a second battery pack at the head of the second queue.

20. The controller according to claim 17, wherein: The controller is further configured to check a health index of the identified battery pack to determine whether the identified battery pack is faulty before instructing the identified battery pack to complete pre-charging of the DC bus.

21. The controller according to claim 17, wherein: The controller is further configured to identify a single battery pack of the plurality of battery packs having a lowest state of charge and place the single battery pack at the head of the queue.

22. The controller according to claim 17, wherein: The second queue is saved to memory for subsequent pre-charging of the DC bus.

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