Vehicle-to-vehicle charging box for conducting a DC fast charging session

Abstract

Charging box (14) for performing a DC fast charging session, DCFC session of a charge-receiving system, “receiver” (12R), by means of a charge-supplying system, “donor” (12D), the charging box (14) comprising: a portable enclosure (40) with an input charging port (42) and an output charging port (142), each connectable to the donor (12D) and the receiver (12R); a high-voltage bus, HV bus (56); first and second sets of HV disconnect devices (62, 162) connected to and configured with the HV bus (56) to connect or disconnect the respective input and output charging ports (42, 142) to the HV bus (56); several DC-DC converters, DC-DC converters (44, 46) connected to the portable enclosure (40) are connected, wherein the multiple DC-DC converters (44, 46) (i) a high-voltage-to-high-voltage converter, HV-HV converter (44) connected to the HV bus (56), and (ii) a high-voltage-to-low-voltage converter,HV-LV converter (46) connected to the HV-HV converter (44); a low-voltage energy storage device, LV energy storage device (48) connected to the portable enclosure (40) and the HV-LV converter (46); a communication processing unit, CPU (55) connected to and configured with the LV energy storage device (48) to establish and maintain two-way communication between the donor (12D) and the receiver (12R) during the DCFC session; and a control system (61) configured during the DCFC session to selectively command the HV-LV converter (46) to precharge the HV bus (56) between the input charging port (42) and the HV-HV converter (44), to charge the LV energy storage device (48), and to selectively command a discharge of a DC charging current from a battery pack of the donor (12D) through the HV-HV converter (44) and to a battery pack of the receiver (12R),wherein for precharging the HV bus (56) the HV-LV converter (46) is operated in a boost mode, so that the internal switching and power transformation operations of the HV-LV converter (46) are used to raise the voltage level of the LV energy storage device (48) to the high voltage level of the donor (12D), and wherein the system controller (61) switches the HV-LV converter (46) into a voltage-reducing "buck" mode when DCFC contactors (20) on board the donor (12D) and the first set of isolating devices (62) are closed to maintain the LV energy storage device (48) at a calibrated low voltage level (between 12 and 15V).

Description

Plug-in hybrid electric vehicles, fully electric vehicles, and extended range electric vehicles, referred to herein as EVs for convenience, are equipped with an electrified powertrain system. One or more electric traction motors of the electrified powertrain are powered by a controlled discharge of a high voltage traction battery pack. An energized traction motor generates output torque that is in turn transmitted to one or more wheels of the electric vehicle. The electric vehicle is thus driven by the electrically driven rotation of the wheels on the road.The electrochemical battery cells of a discharged traction battery pack of a typical electric vehicle may be selectively charged by an external plug-in charging method, with some battery packs also being rechargeable during operation of the electric vehicle by regenerative braking or other regenerative functions. As known in the art, off-board charging requires that the battery pack be electrically connected to an AC or DC (Electric Vehicle Supply Equipment) charging station via a charging cable. After the communication and control circuits of the charging station and the electric vehicle establish two-way communication according to an appropriate charging protocol, the charging station outputs a charging current to the discharged battery pack, thereby charging the individual cells of the battery pack up to a threshold of the state of charge or voltage capability.US 2022 / 0 247 185 A1 discloses an apparatus and a method for vehicle-to-vehicle and / or vehicle-to-load charging. The apparatus comprises a multifunction DC power supply unit and an interface unit configured to perform the charging of the battery between a battery-operated transmitter device and a battery-operated receiver device. The interface unit is configured to detachably accommodate the multifunction DC power supply unit.DE 10 2021 122 038 A1 discloses a vehicle charging device for vehicle-to-vehicle charging. The charger includes two charging connectors configured to be coupled to DC charging terminals of two vehicles each having a battery, a buck-boost converter connected between the two charging connectors and configured to convert a first DC voltage to a second DC voltage, and a controller. The controller is configured to wirelessly connect to a mobile device to obtain a charging instruction identifying a donor vehicle and a receiver vehicle among the two vehicles, and in response to the two charging connectors being coupled to the DC charging ports of the donor vehicle and the receiver vehicle, issue a request for charging permission to a digital device associated with at least one of the vehicles. The controller is further configured to, in response to receiving the charge grant, start a charge session by transferring an electrical charge from the donor vehicle to the receiver vehicle via the buck-boost converter.DE 11 2021 004 888 T5 discloses a DC bus charging module having a DC boost converter configured to apply an output DC voltage from the DC boost converter and having a first voltage level to a DC bus cable. The DC bus cable is separated from a first DC voltage source. Further, the DC boost converter is configured to charge an electrical charge storage device electrically connectable to the DC bus cable with an output DC voltage from the DC boost converter and a second voltage level different from the first voltage level. The DC bus cable is disconnected from the first DC voltage source.Here, a portable charging circuit accessory, hereinafter referred to simply as a charging box, and a corresponding method of performing chargings between a charge supplying system ("donor") and a charge receiving system ("receiver") using the charging box will be described. The underlying charging architecture, circuitry, and charging strategy as described in detail herein enables the transfer of high voltage energy between the donor and receiver systems, for example, full battery powered electric vehicles or plug-in hybrid electric vehicles (EVs), or possibly between two battery powered electric systems in non-EV extensions of the present teachings.According to the invention, a charging box for performing a direct current fast charging, DCFC, session of the receiver by means of the donor comprises a portable housing having an input charging port and an output charging port, which are connectable to the donor and the receiver, respectively. The charging box also includes a high voltage, HV, bus, first and second sets of HV separators connected to the HV bus and configured to connect and disconnect the respective input and output charging terminals to and from the HV bus, and one or more direct current, DC-DC, converters connected to the portable housing. The DC-DC converter / converters include a high voltage-to-high, HV-HV, converter connected to the HV bus, and in some embodiments also a high voltage-to-low, HV-LV, converter connected to the HV-HV converter.An LV energy storage device is connected to the portable case and the above-mentioned HV-LV converter when used. Alternatively, the load box could be connected to an available 12V power supply, for example in a vehicle in such a host system. A communication processing unit, CPU, is configured to establish and maintain two-way communication between the donor and the receiver during the DCFC charging session. A system controller is configured to selectively pre-charge, during the DCFC charging session, the HV bus between the input charging port and the HV-HV converter as needed, charge the optional LV energy storage device when such a device is used, and selectively command a discharge of a DC charging current from a battery pack of the donor through the HV-HV converter and to a battery pack of the receiver. For pre-charging the HV bus, the HV-LV converter is operated in a boost mode such that the internal switching and power transformation operations of the HV-LV converter are utilized to boost the voltage level of the LV energy storage device to the high voltage level of the donor, The system controller switches the HV-LV converter to a voltage-reducing buck mode when DCFC contactors onboard the donor and the first set of separators are closed to maintain the LV energy storage device at a calibrated low voltage level.The portable housing defines a housing volume in one or more embodiments. In such a case, the HV-HV converter, the CPU and the system controller together form part of a charging circuit which is located within the housing volume.The first and second sets of HV separators may include a first set of HV contactors and a second set of HV contactors connected to the input charging port and the output charging port by a corresponding fuse.The optional LV energy storage device may comprise a 12-15 volt battery pack or a 12-15 volt ultra capacitor or supercapacitor, in one or more embodiments.The HV-HV converter may be configured as a buck / boost converter.One aspect of the disclosure includes a human machine interface (HMI) connected to the portable housing. The HMI is configured to receive user input to the system controller during the DCFC session and display information related to the DCFC session.The charging box may also include a thermal management system operable to regulate the temperature of the plurality of DC-DC converters.The above-mentioned CPU comprises respective communication stacks for the donor and the receiver and an application layer connected to the communication stacks to enable two-way communication between the donor and the receiver.The system controller, in turn, may quantify the DCFC charging session as a quantified session after completion thereof to generate a summary of the fees for the DCFC charging session based on the quantified session and to communicate the summary of the fees to a user of the recipient. The system controller may optionally also execute an adaptive self-learning algorithm to analyze the charging behavior of a group of receivers from previous DCFC charging sessions and adjust the power of the charging box over time based on the charging behavior.The receiver and donor may each be configured as a battery powered electric vehicle or a plug-in hybrid electric vehicle; in this case, the DCFC charging session described above is a vehicle-to-vehicle charging session.Also disclosed herein is a vehicle-to-vehicle (V2V) charging box for performing a DCFC session of a charge-receiving vehicle ("receiver") using a charge-supplying vehicle ("donor"). The V2V charging box may include a portable housing defining a housing volume and containing input and output charging ports connectable to the donor and the receiver, respectively. The V2V load box also includes the HV bus, first and second sets of HV contactors connected to the HV bus, and an HV-HV converter connected to the HV bus. The HV-HV converter is configured to output a charging power of at least about 50 kilowatts (kW).The V2V charging box in this embodiment also includes a thermal management system operable to regulate the temperature of the HV-HV converter, and a communication processing unit (CPU) configured to establish and maintain two-way communication between the donor and the receiver during the DCFC charging session. The CPU includes corresponding communication stacks for the donor and the receiver, and an application layer connected to the communication stacks to enable two-way communication between the donor and the receiver.In this embodiment, a system controller is configured to selectively pre-charge the HV bus between the input charging port and the HV-HV converter during the DCFC charging session, charge the optional LV energy storage device when used, and selectively command the discharge of a DC charging current from a battery pack of the donor through the HV-HV converter and to a battery pack of the receiver. The high voltage bus, the first and second sets of HV contactors, the DC-DC converter / converters, the CPU, and the system controller are located within the enclosure volume.A V2V charging method is also disclosed herein, an embodiment of which includes detecting a predetermined electrical connection of the donor and the receiver to a V2V charging box via a system controller thereof. The predetermined electrical connection includes a connection of the donor and the receiver to an input charging port and an output port, respectively, of a portable housing of the V2V charging box. The method also includes establishing two-way communication between the donor and the receiver using a communication processing unit (CPU) of the V2V charging box, the CPU connected to an LV energy storage device within the V2V charging box. The CPU contains corresponding communication stacks for the donor and receiver and an application layer connected to the communication stacks to enable two-way communication.During a V2V charging session, the method includes commanding an HV LV converter of the V2V charging box via a system controller of the V2V charging box to pre-charge an HV bus between the input charging port and an HV HV HV converter of the V2V charging box, selectively charging the LV energy storage device via the HV LV converter, and discharging a DC charging current from a battery pack of the donor via a first set of protecting the V2V charging box, through the HV HV HV HV converter, via a second set of protecting the V2V charging box and to a battery pack of the receiver, thereby performing the V2V charging process. FIG. 1 is an illustration of a representative DCFC operation between a charge delivery vehicle ("donor") and a charge receiving vehicle ("receiver") using the charging box disclosed herein. FIG. 2 shows a simplified connection of the load box of FIG. 1. FIG. 3 shows a representative embodiment of the cargo box shown in FIGS. 1 and 2. FIGS. 4A, 4B, and 4C collectively form a flowchart describing a method of using the charging box of FIGS. 1-3 during a representative V2V charging session.Referring now to the drawings, wherein like reference numerals refer to like features throughout the several views, FIG. 1 depicts a DC fast charging, DCFC, operation in the form of a representative vehicle-to-vehicle charging session (V2V) 10. During the V2V charging operation 10, a charge-supplying electric vehicle (EV), hereinafter referred to simply as donor 12D, delivers a high-voltage DC charging current (DC-1) to a charging box 14, hereinafter referred to as a V2V charging box, without limiting the present teachings to vehicle charging applications. The V2V charging box 14, in turn, supplies a DC charging current (DC-2) to a charge-receiving electric vehicle, i.e., a receiver 12R. The donor 12D and the V2V charging box 14 together appear from the perspective of the receiver 12R as an offboard electric vehicle DCFC charging station (EVSE) of the type mentioned above. Unlike offboard EVSE charging stations that may provide DCFC functionality, the portability and configured functionality of the V2V charging box 14 described below provide the owners / operators of electric vehicles and other electrified systems with the benefit of improved charge mobility and lower range anxiety, among other advantages.The donor 12D and the receiver 12R include a body 13D, 13R and a corresponding electric drive system 50D and 50R. In a typical configuration, the donor 12D has a charge terminal 16 connected to a high voltage electrochemical traction battery pack (B HV) 18 via a series of on-board DCFC contactors 20. The battery pack 18, in turn, is connected to an inverter module (PIM) 22. In a discharge mode of the battery pack 18, the battery pack 18 provides a direct current (VDC) voltage to a direct current side of the PIM 22. The PIM 22, which uses an ON / OFF switching of the conductive state of a plurality of semiconductor switches (not shown) such as IGBTs, MOSFETs, thyristors, or the like, is operated by pulse width modulation or other suitable switching control technique.The switching control of the PIM 22 ultimately converts the DC input voltage from the battery pack 18 to an AC voltage (VAC) suitable for energizing the phase windings of a traction electric motor (M E) 24 causing the machine to rotate. The output torque (arrow T O) of the electric traction motor 24 is then delivered to one or more wheels 26 of the donor 12D. The receiver 12R shown in FIG. 1 may be configured in a similar or identical manner and may include a corresponding charge port 116, a traction battery pack 118, DCFC contactors 120, PIM 122, and a traction electric motor 124. Thus, the respective electric drive systems 50D and 50R are not only configured to perform the V2V charging session 10 of FIG. 1, but are also configured to electrically drive the corresponding donor 12D and receiver 12R during separately performed discharge modes of the battery packs 18 and 118.Referring to FIG. 2, during operation of the receiver 12R, a situation may occur in which the traction battery pack 118 is discharged at least to the extent that the owner / operator of the receiver 12R needs charging. When this situation occurs, the receiver 12R may not be near an available EVSE charging station or home or office charging station. In such a scenario, the same owner / operator according to the present teachings could request to perform the V2V charging session 10 as a DCFC mobile charging session. In this case, the portable V2V charging box 14 could be transported to the location of the receiver 12R, for example, via the donor 12D or other vehicle, and then connected to the donor 12D and the receiver 12R via charging cables 30 and charging ports 16, 116, as described below. The charging ports 16 and 116 may be configured differently depending on the embodiment to accommodate SAE J1772, National Charging Standard (NACS), Combined Charging System (CCS), CHAdeMO, or other suitable charging plugs, and are therefore generally illustrated in FIGS. 1 and 2.As known in the art and as mentioned above, the donor 12D and the receiver 12R are equipped with the above-mentioned traction battery packs 18 and 118, respectively. In addition, the donor 12D includes an on-board vehicle controller 32 (C D) having one or more processors (P) 36, a memory (M) 38, and an instruction set 100S embodying the present method 100 of FIGS. 4A-C. Receiver 12R is similarly equipped with a vehicle controller 132 (C R), one or more processors (P) 136, and a memory (M) 138 having a corresponding version of instruction set 100S. In this manner, the donor 12D and the receiver 12R are capable of communicating via the exchange of data during the V2V charging session 10, managing and coordinating the flow of current, monitoring proper connection of the charging cables 30, and other conditions / fault conditions, regulating the temperature of the V2V charging box 14, and performing other relevant functions during the V2V charging session 10, as described below.To perform the functions of the present method 100, for example, by executing one or more algorithms and automated and / or manual process steps as set forth below, such functions could be embodied by computer readable instructions, i.e., instruction set 100S, from a tangible, non-transitory computer readable storage medium portion of the associated memory 38 and 138. The memories 38 and 138 could include, for example, magnetic or optical media, CD-ROM, and / or solid-state / semiconductor memories (e.g., various types of RAM or ROM). The term "vehicle controller" and related terms such as control module, controller, processor, and similar terms may refer to one or various combinations of application specific integrated circuits (ASIC), field programmable gate arrays (FPGA), electronic circuits, central processing units, for example microprocessors and associated non-transitory memory components in the form of memory and storage devices (read-only, programmable read-only, random access, hard disk drives, etc.). The non-transitory components of memory 38 and 138 used herein are capable of storing machine readable instructions in the form of one or more software or firmware programs or routines, combinational logic circuits, input / output circuits and devices, signal conditioning and buffer circuits, and other components that can be accessed by one or more processors 34 and 134 to provide the described functionality.Still referring to FIG. 2, in a representative embodiment, the V2V charging box 14 contemplated herein is configured to output a rated charging power of at least about 50-100 kilowatts (kW) continuous power and about 150-300 amperes (A) continuous output current. In one possible construction, the V2V load box 14 could receive about 350-1000 V or more from the donor 12D and in response deliver about 150-1000 V or more to the receiver 12R, with other voltage ranges also possible, depending on the embodiment. The V2V charging box 14 is also configured with buck / boost capabilities to enable the V2V charging box 14 to decrease (buck) or increase (boost) the DC voltage (DC-1 of FIG. 1 ) provided by the donor 12D, wherein the V2V charging box 14 does so based on the state of charge (SOC) or voltage capability of the traction battery pack 118 of the receiver 12R, a requested amount of power, the power / SOC / voltage capability of the donor 12D, and other factors.As shown in FIG. 3, the mobile DCFC plug-in functions contemplated herein include coordinated two-way communication of data between the donor 12D and the receiver 12R. The data exchange takes place in the form of a low-voltage control or communication signal (comms), typically in the range of 0-12 V, and an approximate voltage signal (prox) of 0-5 V. A ground (GND) is also present. For example, via an established J1772 connection, the respective processors of the donor 12D and the receiver 12R may communicate with each other via power line communication (PLC) for the comms signal, which in turn occurs according to an established communication protocol via a coordinated exchange of data messages. The comms signal is typically used to verify a connection between an offboard EVSE charging station and a charging EV, the respective locations of which are occupied here by the donor 12D and the V2V charging box 14 (which together function as such an EVSE charging station), and the receiver 12R to communicate states of charge. This can be done, for example, using a fixed duty cycle during the DC charge under consideration. The same signal can be used to adjust the charging speed as needed. Other standards such as the above-mentioned NACS, CCS, CHAdeMO, etc. may be used in a similar manner, so that the particular charging standard may vary depending on the desired end application.The multipolar charging plugs 30C attached to the charging cables 30 are connected to one of the corresponding charging ports 16, 116 located at the donor 12D and the receiver 12R, respectively (see FIG. 1 ). In accordance with the appropriate charging protocol, DC current is conducted through the conductive pins of charging terminal 16 of donor 12D into traction battery pack 118 of receiver 12R via V2V charging box 14. The DCFC charging process is coordinated via an exchange of data / messages between the processor 36 of the donor 12D of FIG. 2, a processor or system controller 61 of the V2V charging box 14, and the corresponding processor 136 of the receiver 12R, for example a battery management system or other battery controller. The above mentioned communication and approach signals are exchanged between the processors 36, 136 and 61, the general process of DC charging according to DIN 70121 or other relevant protocols being well known in the art. As is known in the art, such protocols run after a defined multi-level electronic "handshaking" process before power transfer is possible; this process is described below in the description of method 100.V2V Lade Content: The V2V Lade 14 shown in FIG. 2, configured to function as a DCFC accessory for performing a V2V charging / V2V charging session, may include a portable housing 40, such as a weather-proof, robust, and sufficiently light housing made of molded plastic, aluminum, steel, etc., for example. Portability of the housing 40 may be facilitated by the connection or attachment of wheels and / or handles (not shown) to the housing 40.The housing 40 is also connected to the respective input and output charging ports 42 and 142, which in turn are connectable to the donor 12D and the receiver 12R, respectively, during the V2V session 10.The housing 40 defines a housing volume 400. One or more DC-DC converters (DC-DC converters) are arranged in the housing volume 400 and are connected to the housing 40 for safe transport and operation. In the illustrated embodiment of FIG. 3, such converters include an HV-HV converter 44, for example, an HV buck / boost converter, and a high voltage-low voltage converter 46. An optional LV energy storage device 48, for example, an electrochemical battery pack, an ultra capacitor, or a super capacitor in various implementations, could be connected to a low voltage side of the HV-LV converter 46, as shown, or the low voltage energy could be provided separately, for example, via a plug connection to the 12-15 V on-board voltage. The optional LV energy storage device 48, when used, is also electrically connected to the HV-HV converter 44 to provide low voltage current (e.g., nominally 12-15 V) suitable for opening / closing the HV separators 62 and 162 and for supplying voltage or current sensors 63 and associated circuit and diagnostic components. The connection of the LV energy storage device 48 to the HV LV converter 46 also allows the HV LV converter 46 to selectively charge the LV energy storage device 48 during the V2V charging process 10. Optional LV energy storage device 48 may also be charged via the AC grid in some configurations, for example, by plugging housing 40 into an available outlet via a corresponding charging outlet 49 disposed thereon. Use of such an AC outlet 49 would allow LV energy storage device 48 to be charged via a wall-connected adapter / outlet (not shown) in donor 12D, which may be particularly useful when V2V charging box 14 was inactive for a longer period of time between V2V charging sessions 10.The V2V load box 14 shown in FIG. 3 also includes a communication processing unit (CPU) 55 operable to establish and maintain two-way communication between the donor 12D and the receiver 12R during the V2V load session 10. Separate communication circuits / stacks or comm stacks 58 and 158 (comm S) may be included in the CPU 55 with an application layer 60 interposed therebetween to coordinate wired / wireless communication. The communication stacks 58 and 158 in the non-limiting embodiment of FIG. 3 may include various connections and components, for example, a ground connection (GND) 59A, a SAE J1772 PWM block 59B, and a PLC processor 59C for the communication stack 58, or equivalent structure in other embodiments, and a corresponding ground connection 159A, PWM block 159B, and process 159C for the communication stack 158.To this end, CPU 55 may be equipped to coordinate with the above-mentioned processors 36 and 136 of the respective donor 12D and receiver 12R during the V2V charging session 10. Communication is enabled via one or more communication modules connected / usable with the application layer 60, for example, a BLE / WiFi / LTE software module 60A, an ISO-20 communication software module 60B, a DIN communication software module 60C, and an ISO-3 communication software module 60D as shown in the example non-limiting construction of FIG. 3. As known in the art, such software is typically used during EV charging to enable wireless exchange of data, and is therefore well understood in the art.Using the communication stacks 58 and 158, the application layer 60, and the associated software modules 60A, 60B, and 60 c, the CPU 55 may command the HV LV converter 46 to pre-charge an HV bus 56 of the V2V charging box 14 to a level corresponding to that of an HV bus located on the donor 12D, and selectively recharge the LV energy storage device 48 via the HV LV converter 46 as needed. Moreover, in close coordination with the processors 36 and 136 of FIG. 2, the CPU 55 selectively commands the discharge of a DC charge from the traction battery pack 18 of the donor 12D of FIGS. 1 and 2 to the traction battery pack 118 of the receiver 12R through operation of the HV-HV converter 44. the DC-DC converter / converters, i.e., the HV-HV converter 44 and the optional HV-LV converter 46, together with the optional LV energy storage device 48, the CPU 55, the system controller 61, and the associated hardware and software, form a V2V charging circuit 14C located within the housing volume 400, the system controller 61, in turn, forming one or more processors, This is also intended to include memory and other hardware as indicated above.Still referring to FIG. 3, the V2V load box 14 and the load circuit 14C therein include first and second sets of HV separators 62 and 162, respectively. The HV-HV converter 44 is connectable to positive and negative high voltage rails (+, -) between the input charge terminal 42 and the output charge terminal 142 via the first and second groups of HV separators 62, 162, respectively. Fault separators 57, such as fuses, pyrotechnic switches, or E-fuses, may be arranged as shown to provide additional high voltage protection.Other components of the V2V load box 14 may include a human-machine interface (HMI) 70 connected to the portable housing 40 and configured to facilitate human-machine interactions during the course of the V2V load session 10 of FIGS. 1-3. The HMI 70 could receive user input to the system controller 61 during the V2V charging session 10 and display information regarding the V2V charging session 10 for viewing by users of the V2V charging box 14. For example, the HMI 70 could include one or more screens, alphanumeric touch screens, keyboards, and / or other peripheral devices that present prompts and sequential commands to the owner / operator that need to track them. The HMI 70 could also display information to the user(s), such as the current communication and charging status of the V2V session 10, the SOC, voltage or other status of the traction battery pack 18 and 118 of the respective donor 12D and receiver 12R, the charging time and total discharged power, etc. A controller area network (CAN) bus may be incorporated into the architecture of the V2V charging box 14 to communicate between the various modules or devices via low voltage differential signals.Additionally, a thermal management system (TMS) 72 could be incorporated into or connected to the V2V load box 14 to regulate the temperature of the high voltage and other components contained therein, particularly the HV-HV converter 44 and the optional HV-LV converter 46. In some embodiments, thermal management system 72 could include optional phase change materials to optimize mass, transient heat dissipation capability, etc.In general, the method 100 described below includes detecting, via the system controller 61 thereof, a predetermined electrical connection of the donor 12D and the receiver 12R to the load box 14, wherein the predetermined electrical connection includes connecting the donor 12D and the receiver 12R to the respective input load port 42 and the output port 142 of the portable housing 40 shown in FIG. 3. The method 100 also includes establishing two-way communication between the donor 12D and the receiver 12R using the CPU 55 of the load box 14 as described above. During the V2V charging session 10, the method 100 may include commanding, via the system controller 61 of the charging box 14, the HV LV converter 46 (if used) to pre-charge the HV bus 56 between the input charging port 42 and the HV HV HV converter 44, selectively charging the optional LV energy storage device 48 via the HV LV converter 46. The method 100 may also include discharging a DC charging current from the battery pack 18 of the donor 12D via the first set of separators 62, for example, HV contactors of the charging box 14, through the HV-HV converter 44, via the second set of separators 162 of the charging box 14, and to the battery pack 118 of the receiver 12R, thereby performing the V2V charging session 10. Gate drive signals, mode control signals, and controller area network (CAN) messages may be used by the system controller 61 for such purposes as shown in FIG. 3. A more specific implementation will now be described with reference to FIGS. 4A-4C.Referring to FIGS. 4A, 4B, and 4C, these three figures collectively illustrate an embodiment of the method 100 that uses discrete process steps, segments, or blocks for clarity. Each individual block of the method 100 may be implemented in the order set forth herein to perform the V2V charging session 10 using the hardware of FIG. 3.Referring to FIG. 4A, the method 100 begins with block B 102 with a request for emergency charging of the charge receiving vehicle or receiver 12R of FIGS. 1-3. For example, an owner / operator of the receiver 12R could transmit a request to an owner / operator of the charging vehicle or donor 12D, request a V2V charging session via a text message or a telephone call using OnStar ® or otherwise signal a need or desire for a mobile DCFC event. The method 100 then proceeds to block B 104.In block B 104, the donor 12D arrives at the location and is parked near the receiver 12R. The donor 12D could park in front of or next to the receiver 12R in this case, so that the charging ports 16 and 116 are easily accessible. The method 100 then proceeds to block B 106.Block B106 of FIG. 4A includes connecting the charging cable 30 to the donor unit 12D and the V2V charging box 14 of FIGS. 1-3. For example, the charging cord 30 could be a CCS / NACS charging cord as mentioned above, wherein one end of the cord 30 could be inserted into the charging port 16 on the donor 12D and an opposite end of the same cord 30 could be inserted into the input charging port 42 on the V2V charging box 14 (see FIG. 3 ). Block B 106 may also be reached by block B 113 of FIG. 4A as part of method 100, as described in detail below. The method 100 proceeds from block B 106 to block B 108 once the charging cord 30 is securely connected between the donor 12D and the V2V charging box 14.In block B 108, which is analogous to block B 106, another charging cable 30 is connected between the output charging port 142 of the V2V charging box 14 and the charging port 116 of the receiver 12R. Thus, after completion of block B 108, the donor 12D is electrically connected to the receiver 12R via the intervening V2V load box 14. The method 100 then proceeds to block B 110.Block B 110 of FIG. 4A includes turning on the V2V charging box 14 so that the V2V charging box is supplied with low voltage current. For example, a soft or hard switch could be activated by the user of the V2V charging box 14 to provide the low voltage power from the LV energy storage device 48 of FIG. 3 to the CPU 55 and other low power devices or from another 12V power supply. After completion of block B 110, the method 100 of FIG. 4A reaches point A in the illustrated process flow.Referring to FIG. 4B, and beginning with point A (see FIG. 4A ), the method 100 proceeds to blocks B 112 to start the functions of the donor 12D and to block B 117 to start the functions of the receiver 12R. Here, the V2V session 10 of FIGS. 1-3 is initiated. For example, the human machine interface (HMI) 70 of the V2V load box 14 could be accessed, either directly or via a portable electronic device such as a smartphone or a tablet computer. The user could request a discharge of the high voltage energy from the traction battery pack 18 of the donor 12D, which would then initiate the remaining charging sequence. The method 100 proceeds to block B 113 after completion of block B 112.In block B113, it is determined whether an electronic handshake signal, for example a transport layer security (TLS) handshake, has been received by the receiver 12R through the donor 12D. As known in the art, such a handshake signal is often used to establish an encrypted two-way communication session between a charge provider and a charge receiver during charging of electric vehicles. This is extended to the present DCFC / V2V charging scenario. The method 100 continues to block B 114 if the handshake signal was received from the donor 12D, and alternatively to block B 106 of FIG. 4A if the handshake signal is not detected.In block B 114 of FIG. 4B, after confirming receipt of the electronic handshake signal in the previous block B 113, the receiver 12R notifies the V2V charging box 14 of its power and current limits via the established power line connection through the intervening charging cable 30. In turn, the V2V charging box 14 notifies the receiver 12R of the power and current limits of the donor 12D and the V2V charging box 14 such that the receiver 12R views the combination of the donor 12D and the V2V charging box 14 as a single charging unit, i.e., analogous to an offboard EVSE charging station. The V2V charging box 14 responds to the successful handshake with a precharge of the DC bus 56 of FIG. 3. To do so, the HV LV converter 46 of FIG. 3 is operated in boost mode, such that the internal switching and power transformation operations of the HV LV converter 46 are used to boost the voltage level of the LV energy storage device 48 to the high voltage level of the donor 12D. Thereafter, the method 100 proceeds to block B 115.In block B 115, it is determined via the system controller 61 of the V2V charging box 14 whether the DCFC contactors 20 (FIG. 2 ) located on the donor 12D are closed and also whether the first set of separators 62 of the V2V charging box 14 of FIG. 3 is also closed. The method 100 continues to block B 106 of FIG. 4A when the DCFC contactors 20 or the isolation devices 62 of the V2V load box 14 are not closed, and alternatively to block B 116 when the DCFC contactors 20 and the isolation devices 62 are both in a closed state.Block B 116 is executed when the DCFC contactors 20 on board the donor 12D and the first set of separators 62 of the V2V load box 14 are closed. In this case, the system controller 61 switches the HV LV converter 46 to a voltage reducing "buck" mode to maintain the LV energy storage device 48 at a calibrated low voltage level, for example nominally 12-15V, as mentioned above. The method 100 proceeds to block B 118 once the buck mode has been activated.In block B 117 which is analogous to block B 113, the system controller 61 of the V2V load box 14 checks whether the handshake signal has been received from the donor 12D. In this case, the V2V load box 14 acts as resident logic for the receiver 12R. The method 100 continues to block B 118 if the handshake signal was received and to block B 106 of FIG. 4A if the expected handshake signal is not detected.In block B118 of FIG. 4B, the HV-HV converter 44 of the V2V load box 14 is commanded to take in the precharge voltage from block B114. Because the particular voltage requirements of the receiver 12R may vary for a particular charging event, the HV-HV converter 44 may operate in either a buck mode (boosting) or a boost mode (boosting) as needed at block B118. The method 100 then proceeds to block B 120.In block B 120, the DCFC contactors 120 of the receiver 12R are verified as closed in a process step analogous to that performed in block B 115. Then, the method 100 proceeds to block B122. Otherwise, the method 100 repeats block B117.In block B122, the energy transfer process is initiated in response to the foregoing process steps. The system controller 61, which cooperates with the controllers 32 and 132 of FIG. 2, commands a high voltage DC charge to be discharged from the traction battery pack 18 of the donor 12D to the traction battery pack 118 of the receiver 12R via the intervening V2V charging box 14. Block B122 may also be reached by block B129 of FIG. 4C, as described below. In the further course of this process, the method 100 proceeds to blocks B 124 and B 126.In blocks B 124 and B 126 of FIG. 4B, the traction battery pack 18 of the donor 12D is discharged and the traction battery pack 118 of the receiver 12R is charged, respectively. Thus, the method 100 reaches point B in the illustrated process flow.Referring to FIG. 4C, and beginning with point B, the method 100 continues to block B125. Here, the CPU 55 and / or other participating circuitry of the donor 12D and the receiver 12R scan for a cable / disconnect fault. Such a fault could occur when one of the charging cables 30 disengages or disengages. The method 100 continues to block B 132 if such an error is detected. The method 100 alternatively proceeds to block B 127 if no such error is present.In block B127, the system controller 61 of FIG. 3 checks whether a respective state of charge (SOC) of the donor 12D and the receiver 12R has reached a predetermined SOC limit. If so, the method 100 proceeds to block B128, otherwise to block B129.Block B128, which is reached when the SOC of the donor 12D or the receiver 12R reaches the predetermined SOC limit of block B127, includes terminating the DCFC charging from the perspective of the receiver 12R. This could mean that the required signals are transmitted from the communication stack 158 to the V2V load box 14 to indicate that the receiver 12R no longer needs to be loaded. As part of block B128, the system controller 61 may command the opening of the disconnect 162, thereby disconnecting the high voltage connection between the V2V load box 14 and the receiver 12R. On board the receiver 12R, the DCFC contactors 120 of FIG. 1 are also commanded to open. The method 100 then proceeds to block B 130.Next, in block B129, the system controller 61 of the V2V load box 14 determines whether a user has requested termination of the V2V session 10. For example, the owner / operator of the donor 12D or the receiver 12R could communicate the desire to end the V2V charging session 10 via a wireless or HMI-based communication with the CPU 55, for example, via the HMI 70 of FIG. 3 and / or via an app as mentioned above. The method 100 continues to block B128 when the user requests that the V2V charging session 10 be terminated.Block B130, analogous to block B128, involves terminating the V2V session 10 from the point of view of the donor 12D. This operation is performed in close agreement with the above-described operation of block B128. Thereafter, the method 100 proceeds to block B136.In block B132 of FIG. 4C, the V2V load box 14 of FIGS. 1-3 interrupts its power transmission to the receiver 12R in response to the cable / disconnect fault detected in block B125. The method 100 then proceeds to block B134.In block B 134, the handshake signal described above is aborted and the V2V charging session 10 is ended. Thereafter, the method 100 proceeds to optional block B136.Block B136 of FIG. 4C may be used in one or more embodiments to quantify the recently completed V2V session 10 and thereafter end the V2V charging session 10 in block B138. For example, the V2V charging box 14 or its use could include communication with an offline or backend payment system, for example, processing a debit or credit card, use of a mobile payment application accessible via a user device such as a smartphone or a tablet computer, etc. Cloud connectivity enabled by a local WiFi connection, long term evolution (LTE), BLUETOOTH, or other suitable communication link to transmit data describing the V2V session 10 to a backend server to quantify the V2V charging session 10. That is, the system controller 61 may be configured to quantify the V2V charging session 10 after completion thereof as a quantified session to make a summary of the fees for the V2V charging session 10 based on the quantified session. The system controller 61 could then communicate the summary of the charges to a user of the receiver 12R. This would allow a mobile DCFC provider to be compromised for its cost via the V2V load box 14.Similar technology could also enable communication with other vehicles / devices. To this end, the V2V loadbox 14 shown in Figures 1-3 could be assigned a unique alphanumeric identifier which, in turn, would allow the aforementioned backend server to identify the parties involved in the V2V load session 10. This, in turn, would allow the party having the authority of the V2V load box 14 to bill or withdraw payment for the completed V2V load session 10 using established digital payment techniques. For example, block B 136 could include outputting a summary and / or calculation of the elapsed charge time / duration, the state of health of the traction battery pack 118, the total charge power provided to the receiver 12R, and the associated cost of providing that charge power to the receiver 12R.Optionally, the V2V loadbox 14 or the backend server mentioned above could be configured to create unique user profiles of load parameters for a particular group of recipients 12R, such as similarly equipped EVs. The V2V load box 14 could use an adaptive self-learning algorithm or other techniques to analyze the collective charging behavior of such a group of receivers 12R from previous V2V sessions 10, which would enable the V2V load box 14 to adjust the performance of the V2V load box 14 and improve the charging experience for future uses. The method 100 is completed after completion of the optional quantification / monetarization process of block B134. The LV energy storage device then enters a low power standby mode until the V2V charging box 14 is again needed for a subsequent V2V charging session.The above-described mobile DCFC-related hardware and software solutions thus provide an electrical architecture that enables energy transfer between two EVs or other battery-electric systems equipped with a high-voltage rechargeable energy storage device, here exemplarily shown as the traction battery packs 18 and 118 of FIGS. 1 and 2. The portability of the originally self-supplied V2V load box 14 and its configured DCFC capabilities enables faster, more flexible and user friendly DCFC loading in a V2V context compared to such alternative approaches. These and other attendant advantages will be readily understood by those skilled in the art in view of the foregoing disclosure.

Claims

A charging box (14) for performing a DCFC, charge receiving, "receiver" (12R) session via a charge delivery, "donor" (12D), the charging box (14) comprising: a portable housing (40) having an input charging port (42) and an output charging port (142) connectable to the donor (12D) and the receiver (12R), respectively; a high voltage, HV, bus (56); first and second sets of HV separators (62, 162) connected to the HV bus (56) and configured to connect or disconnect the respective input and output charging ports (42, 142) to and from the HV bus (56); a plurality of DC-DC, DC-DC, converters (44, 46) connected to the portable housing (40), the plurality of DC-DC converters (44, 46) comprising (i) a high voltage-high voltage, HV-HV, converter (44) connected to the HV bus (56), and (ii) a high voltage-low voltage, HV-LV, converter (46) connected to the HV-HV converter (44); a low voltage energy storage, LV, energy storage device (48) connected to the portable housing (40) and the HV-LV converter (46); a communication processing unit, CPU (55), connected to the LV energy storage device (48) and configured to establish and maintain two-way communication between the donor (12D) and the receiver (12R) during the DCFC session; and a system controller (61) configured to selectively command the HV-LV converter (46) to pre-charge the HV bus (56) between the input charging port (42) and the HV-HV converter (44), charge the LV energy storage device (48), and selectively command a discharge of a DC charging current from a battery pack of the donor (12D) through the HV-HV converter (44) and to a battery pack of the receiver (12R), wherein, for pre-charging the HV bus (56), the HV-LV converter (46) is operated in a boost mode such that the internal switching and power transformation operations of the HV-LV converter (46) are utilized to boost the voltage level of the LV energy storage device (48) to the high voltage level of the donor (12D), and wherein the system controller (61) switches the HV-LV converter (46) to a voltage reducing "buck" mode when DCFC contactors (20) onboard the donor (12D) and the first set of separators (62) are closed to maintain the LV energy storage device (48) at a calibrated low voltage level (between 12 and 15V).The charging box (14) of claim 1, wherein the portable housing (40) defines a housing volume (400), and wherein the plurality of DC-DC converters (44, 46), the LV energy storage device (48), the CPU (55), and the system controller (61) collectively form a charging circuit (14C) disposed within the housing volume (400).The load box (14) of claim 1, wherein the first and second sets of HV separators (62, 162) comprise a first set of HV contactors and a second set of HV contactors connected to the input charge port (42) and the output charge port (142) by a corresponding fuse (57).The charging box (14) of claim 1, wherein the LV energy storage device (48) comprises a 12-15 volt battery pack.The charging box (14) according to claim 1, wherein the HV-HV converter (44) is a step-down / step-up converter.The charging box (14) of claim 1, further comprising: a human machine interface, HMI (70), connected to the portable housing (40), wherein the HMI (70) is configured to receive user input to the system controller (61) during the DCFC session and display information related to the DCFC session.The charging box (14) of claim 1, further comprising: a thermal management system (72) operable to regulate the temperature of the plurality of DC-DC converters (44, 46).The charging box (14) of claim 1, wherein the CPU (55) comprises respective communication stacks (58, 158) for the donor (12D) and the receiver (12R) and an application layer (60) connected to the communication stacks (58, 158) to enable two-way communication between the donor (12D) and the receiver (12R).The charging box (14) of claim 1, wherein the system controller (61) is configured to quantify the DCFC session after completion thereof as a quantified session, generate a summary of the fees for the DCFC session based on the quantified session, and transmit the summary of the fees to a user of the recipient (12R).The charging box (14) of claim 1, wherein the receiver (12R) and the donor (12D) are both configured as a battery powered electric vehicle or a plug-in hybrid electric vehicle, and wherein the DCFC session is a vehicle-to-vehicle session.

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