BATTERY PACK SELECTION FOR PRE-CHARGING OF DC BUS

The present disclosure provides a system and method for selecting a battery pack that is used to pre-charge a high-voltage DC bus of an electric vehicle. A round-robin architecture is disclosed that prevents repeat selection of battery packs in order to prevent burnout of a resistor of the battery pack resulting from rapid subsequent pre-charging events. The system and method provided includes an easy solution that is scalable to a system with any number of battery packs, does not require any additional hardware, and is an inexpensive technique to protect an expensive component of the electric vehicle.

TECHNICAL FIELD OF THE PRESENT DISCLOSURE

The present disclosure relates to the pre-charging of a DC bus in an electric or hybrid vehicle. More specifically, the present disclosure relates to a system and method of selecting a battery pack for pre-charging the DC bus of an electric or hybrid vehicle.

BACKGROUND OF THE PRESENT DISCLOSURE

In vehicles having multiple battery packs connected in a parallel configuration, pre-charging a high-voltage DC bus must be completed by at least one of the battery packs before any of the battery packs within the configuration can close their contactors to allow for vehicle operation. Each battery pack includes one pre-charge circuit comprising a resistor, which dissipates power through heat. As a result, overuse of a resistor causes the overused resistor to burnout.

Because each battery pack includes a single pre-charge circuit, using the same battery pack to pre-charge the high-voltage DC bus repeatedly in quick succession will damage the resistor, leading to an inoperable battery pack, which is expensive to replace and otherwise complicated to fix. This problem is particularly prevalent and significant in electric vehicles, especially where operator behavior determines how often pre-charging of the high-voltage DC bus will occur. For example, if the contactors in each battery pack must close with every key switch-on to operate the vehicle, the pre-charge of the high-voltage DC bus must occur with every key switch-on. To avoid premature resistor burnout and battery pack failure, solutions including additional hardware or software or hardware add-ons for individual battery packs have been proposed. However, these solutions are not ideal and improvements are desired.

SUMMARY OF THE PRESENT DISCLOSURE

The present disclosure provides a system and method for selecting a battery pack that is used to pre-charge a high-voltage DC bus of an electric vehicle. A round-robin architecture is disclosed that prevents repeat selection of battery packs in order to prevent burnout of a resistor of the battery pack resulting from rapid subsequent pre-charging events. The system and method provided includes an easy solution that is scalable to a system with any number of battery packs, does not require any additional hardware, and is an inexpensive technique to protect an expensive component of the electric vehicle.

In an embodiment of the present disclosure, a system for selecting a battery pack of a vehicle is disclosed. The system comprises a plurality of battery packs connected to each other 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 batter packs so that at least one of the plurality of battery packs is configured to selectively pre-charge the DC bus in a DC bus pre-charge event. The controller is configured to assemble a queue according to usage of the plurality of battery packs to pre-charge the DC bus and save the queue to the memory for subsequent usage.

A head of the queue may include a battery pack of the plurality of battery packs having a lowest state-of-charge than the remaining battery packs. The controller may be configured to receive a saved queue from the memory for a subsequent DC bus pre-charge event. The controller may be configured to receive a health index of any of one battery pack of the plurality of battery packs to determine if any one battery pack of the plurality of battery packs is faulty. A different queue may be assembled after every DC bus pre-charge event relative to an immediately previously used queue.

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

The method may further comprise determining whether the pre-charge of the Dc bus was successfully completed. When the pre-charge of the DC bus is not successfully completed, the method may further comprise requesting a second identification of a second battery pack positioned at a head of the second queue; instructing the second battery pack to complete pre-charge of the DC bus; determining whether pre-charge of the DC bus was successfully completed; pushing the second battery pack to a tail of the second queue to create a third queue; and repeating until the pre-charge of the DC bus is successfully completed. When the pre-charge of the DC bus is successfully completed, the method may further comprise initiating operation of the vehicle.

The method may further comprise reviewing a health index of the identified battery pack prior to instructing the identified battery pack to complete pre-charge of the DC bus to determine whether the identified battery pack is faulty. When the battery pack is faulty, the method may further comprise requesting a second identification of a second battery pack positioned at a head of the second queue; reviewing a 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 comprise pushing the second battery pack to a 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 comprise initiating vehicle operation after the pre-charge of the DC bus is completed.

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 of a plurality of battery packs having a lowest state-of charge than the remaining battery packs; instructing the identified battery pack to pre-charge a DC bus; storing the identified battery pack within a memory; creating a queue, wherein the identified battery pack is positioned at a head of the queue; and pushing the identified battery pack to a tail of the queue to create a subsequent queue. The method may further comprise reviewing a health index of the identified battery pack to determine whether the identified battery pack is faulty.

Additional features and advantages of the present disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiments exemplifying the disclosure as presently perceived.

Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale, and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplification set out herein illustrates an embodiment of the invention, and such an exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring initially toFIG.1, a system100of a vehicle is disclosed. The system100includes a battery master controller102, a non-volatile memory104, and a plurality of battery packs106, wherein the battery packs106are illustratively connected in a parallel configuration. Although the illustrated embodiment discloses six battery packs106, the method and system described herein is scalable and can be applied to a vehicle with any number of battery packs106. The battery packs106may have varying levels of state-of-charge percentages. For example, as shown, battery pack106amay have a lower state-of-charge percentage than battery pack106b. Any battery pack106may have a lower, higher, or equal state-of-charge percentage relative to any other battery pack106.

The battery packs106are operably connected with the battery master controller102and selectively operably connected with a high-voltage DC bus108, wherein the battery master controller102can communicate with each respective battery pack106to initiate pre-charge of the DC bus108using a selected battery pack106as discussed further herein. The battery master controller102may further communicate with each respective battery pack106to control the closing of contactors of the battery packs106for operation of the vehicle once pre-charge of the high-voltage DC bus108is complete. The battery master controller102is also operably connected to the memory104to store pre-charge events as discussed further herein.

Now referring toFIG.2, in view of the components disclosed inFIG.1, a method200for initiating a first DC bus pre-charge event is disclosed. At box202, a user initiates operation of a vehicle. The user may initiate the pre-charge event using any method known in the art to initiate operation of a vehicle. For example, the user may utilize a switch, button, key-on using a standard key, remote start mechanism, use of a smart device application, use of a smart assistant, Bluetooth, key card, fingerprint identification, digital key, voice start, application of the Internet of things, or other mechanisms to initiate the pre-charge event. Before operation of the vehicle occurs, the DC bus108must be pre-charged using one of the plurality of battery packs106.

After user initiation at box202, the controller102identifies the battery pack106having the lowest state-of-charge percentage at box204. For example, referring briefly toFIG.1, the controller102chooses battery pack106a, as battery pack106ahas the lowest state-of-charge percentage among the battery packs106. Referring again toFIG.2in view of the components disclosed inFIG.1, the controller102then sends instructions to the selected battery pack106aat box206to pre-charge the DC bus108during the DC bus pre-charge event indicated at box208. At any point after battery pack106selection at box204, the controller102stores the identity of the pack106awithin the memory104to track the completion of the pre-charge event at box210. At box212, at any point after battery pack106selection at box204the controller102additionally creates a queue302(FIG.3), which is stored in the memory104as indicated by box212. Once the pre-charge event is completed, vehicle operation is initiated at box214. Ideally, the contactors of the remaining battery packs106are closed to allow full vehicle operation at box214.

However, such contactors are only closed upon determination by the controller102that the remaining battery packs106are operable as further discussed herein. In some instances, any number of battery packs106fewer than the remaining battery packs106may be determined by the controller102to be non-operable. If any battery packs106are considered non-operable, the contactors of only the operable battery packs106are closed for vehicle operation. In the event less than all of the battery packs106are operable, the vehicle operates at a performance percentage corresponding to the percentage of battery packs106that are operable.

FIG.3illustrates a round robin architecture300, including the mentioned queue302and additional queues304,306that are generated with repeat instances of user initiation. For example, referring toFIGS.1-3, after the controller102chooses the battery pack106having the lowest state-of-charge percentage (i.e. battery pack106a) at box204of the method200, the controller102generates the queue302as mentioned above. Because battery pack106ais the first selected battery pack, battery pack106ais initially positioned at the head308of the queue302. Upon pre-charge of the DC bus108, the controller102instructs the memory104to move the battery pack106ais to the tail310of the queue, as shown by queue304, to avoid immediate repeat use of the battery pack106awith the next user initiation. For example, if the memory104has queue304stored for use upon next user initiation, the next user initiation will cause the controller102to instruct the battery pack106bto pre-charge the DC bus. Upon pre-charge of the DC bus108, the controller102instructs the memory to move the battery pack106bto the tail310of the queue, as shown by queue306, to avoid immediate repeat use of the battery pack106bwith the next user initiation. The controller102continues to instruct the battery pack106at the head308of the queue in such a matter until all battery packs106have been utilized for a DC bus pre-charge event. At that period, the queue restarts and battery pack106ais again selected.

Now referring toFIG.4Ain view of the components ofFIGS.1and3, a method400is provided for completing subsequent DC bus pre-charge events, following the initial DC bus pre-charge event method200ofFIG.2. In other words, method200is used for the first user initiation of a vehicle, i.e. first vehicle use, first vehicle use after a system reset, first vehicle use after a component of the system has been replaced, or any other instance in which a queue is not saved to memory. After the completion of method200, subsequent user initiation events cause initiation of method400ofFIG.4Auntil circumstances require a system reset or other event which dictates the use of method200.

Method400begins at box402, when a user initiates operation of a vehicle. User initiation may occur in any of the ways discussed herein in reference to method200. After user initiation at box402, the controller102retrieves the queue (i.e. any of queues302,304,306or another, subsequent queue) from the memory104at box404. Identification of the battery pack106at the head308of the queue is also requested at box406. Once the proper battery pack106has been identified at box404, the controller102instructs the respective battery pack106to complete pre-charge of the DC bus108at box408. After a predetermined period of time in which the pre-charge event should be completed, the controller102determines whether the pre-charge of the DC bus108has been completed at box410.

If the pre-charge event has been completed at box410, the battery pack106used during the pre-charge event is pushed to the tail310of the queue at box412, and the resulting queue is saved to the memory104at box416. If the pre-charge event has not been completed at box410, a pre-charge error has occurred and the faulty battery pack106is pushed to the tail310of the queue at box414. The resulting queue is saved to the memory104at box416and the method400restarts at box404until the pre-charge event is successfully completed. Once the pre-charge event is successfully completed, the contactors of the remaining operable battery packs106are closed to allow vehicle operation at box418as discussed above.

In some embodiments, as shown byFIG.4B, a method400bmay be utilized. Method400bis substantially the same as method400illustrated byFIG.4A, with the exceptions described herein. In method400b, if the pre-charge event has not been completed at box410, the processor102may immediately retrieve identification of the next battery pack106at box406b, which simultaneously pushes the faulty battery pack106to the tail310of the queue as shown at box414. The method400brepeats until the pre-charge event is successfully completed at box410. Once the pre-charge event is successfully completed, the battery pack106used during the pre-charge event is pushed to the tail310of the queue at box412, and the resulting queue is saved to memory at box416. The contactors of the remaining operable battery packs106are closed to allow vehicle operation at box418as discussed above. Utilization of method400bmay result in greater efficiency when pre-charging the DC bus of the vehicle.

In some embodiments, the controller102may pre-emptively identify any battery pack issues before the pre-charge event is initiated to avoid pre-charge failure. For example, referring toFIG.5Ain view of the components ofFIGS.1and3, method500is provided for completing subsequent DC bus pre-charge events, following the initial DC bus pre-charge event method200ofFIG.2, wherein the controller102conducts a review of the battery pack health index of the selected battery pack106before initiating the pre-charge of the DC bus.

Method500begins with a user initiation at box502, wherein the user initiation502is similar to the user initiation402of method400and user initiation202of method200. At box504, the controller102retrieves the pre-charge queue (i.e. any of queues302,304,306or another, subsequent queue) from the memory104and further requests the identification of the battery pack106at the head308of the queue. The controller102then conducts a review of the health index of the identified battery pack106at box506. If the identified battery pack106is determined to be faulty at box508, the identified battery pack106is pushed to the tail310of the queue at box510, resulting in a subsequent queue that is saved to the memory104at box516. The method500then restarts at box504until the pre-charge event is successfully completed as described further herein.

If the identified battery pack106is determined not to be faulty at box508, the controller102instructs the identified battery pack106to complete the pre-charge of the DC bus at box512. The battery pack106is then pushed to the tail310of the queue at box514, resulting in a subsequent queue that is saved to the memory104at box516. Once the pre-charge event is successfully completed, the contactors of the remaining operable battery packs106are closed to allow vehicle operation at box518as discussed above.

In some embodiments, as shown byFIG.5B, a method500bmay be utilized. Method500bis substantially the same as method500illustrated byFIG.5A, with the exceptions described herein. In method500b, if the battery pack has been identified as faulty at box508, the processor102may immediately retrieve identification of the next battery pack106at box505b, which simultaneously pushes the faulty battery pack106to the tail310of the queue as shown at box510. The method500brepeats until an operable battery pack106is identified at box508. Once an operable battery pack is identified, the remainder of method500bfollows the same steps as method500as discussed above.