System and method for creating traction control for a hybrid vehicle from electric and regulative vehicle

Abstract

A tandem hybrid vehicle is disclosed. A tandem hybrid vehicle includes a first vehicle having a first drive system, a second vehicle having a second drive system, and a traction hitch for mechanically coupling the second vehicle to the first vehicle for traction by the first vehicle. A communication path is established between the second vehicle and the first vehicle. A processor at the second vehicle receives a signal sent from the first vehicle to a communication device of the second vehicle via the communication path, determines an instruction for operating the second vehicle from the signal, and operates the second drive system and the first drive system based on the instruction, to operate the first vehicle and the second vehicle as a tandem hybrid vehicle.

Description

Technical Field

[0001] The present disclosure relates to operating an electric vehicle towed by a leading vehicle, and in particular, to operating the electric vehicle synchronously with the leading vehicle during towing. Background Art

[0002] A vehicle towed by another vehicle exerts a resistance on the other vehicle, and this resistance may cause wear during the operation of the other vehicle. Therefore, it is desirable to provide a method by which the towed vehicle can operate together with the towing vehicle to assist the vehicles in operating as a unit. Summary of the Invention

[0003] In one exemplary embodiment, a method of towing a second vehicle by a first vehicle is disclosed. A communication path is established between the second vehicle and the first vehicle, and the first vehicle has a first drive system. A signal indicating an instruction for operating the second vehicle is sent from the first vehicle to the second vehicle through the communication path. Based on an instruction to operate the first vehicle and the second vehicle as a series hybrid vehicle, a second drive system of the second vehicle operates together with the first drive system of the first vehicle.

[0004] In addition to one or more features described herein, the method further includes selecting a charging mode for charging a battery pack of the second vehicle.

[0005] In addition to one or more features described herein, the charging mode is one of a fast charging mode, a hybrid charging mode that maintains a target minimum level, a hybrid maximum mode that gives priority to propulsion until the state of charge of the battery pack drops to the target minimum level, and a standard charging mode that charges only when permitted.

[0006] In addition to one or more of the features described herein, the method further includes at least one of the following: applying brakes at the second vehicle when brakes are applied at the first vehicle, and applying torque at the second vehicle in response to an acceleration request from the first vehicle.

[0007] In addition to one or more of the features described herein, the method further includes: operating the first vehicle and the second vehicle as the series hybrid vehicle when the speed of the second vehicle is greater than a speed threshold.

[0008] In addition to one or more features described herein, the method further includes: using data from the second vehicle to determine the speed of the first vehicle when the speed of the first vehicle is not available to the second vehicle.

[0009] In addition to one or more features described herein, the method further includes determining a hitch force between the first vehicle and the second vehicle.

[0010] In another exemplary embodiment, an electric vehicle is disclosed. The electric vehicle includes an electric drive system, a communication device configured to communicate along a communication path between the electric vehicle and a first vehicle, and a processor, the first vehicle having a first drive system, the first vehicle being coupled to the electric vehicle for towing the electric vehicle. The processor is configured to receive a signal transmitted from the first vehicle to the communication device, determine an instruction for operating the electric vehicle based on the signal, and operate the electric drive system of the electric vehicle and the first drive system of the first vehicle based on the instruction to operate the first vehicle and the electric vehicle as a series hybrid vehicle.

[0011] In addition to one or more of the features described herein, the processor is further configured to select a charging mode for charging the battery pack of the electric vehicle.

[0012] In addition to one or more of the features described herein, the charging mode is one of a fast charging mode, a hybrid charging mode that maintains a target minimum level, a hybrid maximum mode that prioritizes propulsion until the state of charge of the battery pack drops to the target minimum level, and a standard charging mode that charges only when permitted.

[0013] In addition to one or more of the features described herein, the processor is further configured to perform at least one of the following: apply braking at the electric vehicle when braking is applied at the first vehicle, and apply torque at the electric vehicle in response to an acceleration request from the first vehicle.

[0014] In addition to one or more of the features described herein, the processor is further configured to operate the first vehicle and the electric vehicle as the series hybrid vehicle when the speed of the electric vehicle is greater than a speed threshold.

[0015] In addition to one or more of the features described herein, the processor is further configured to use data from the electric vehicle to determine the speed of the first vehicle when the speed of the first vehicle is not available to the electric vehicle.

[0016] In addition to one or more of the features described herein, the processor is further configured to determine the hitch force between the first vehicle and the electric vehicle.

[0017] In yet another exemplary embodiment, a series hybrid vehicle is disclosed. The series hybrid vehicle includes a first vehicle having a first drive system, a second vehicle having a second drive system, a towing hitch for mechanically coupling the second vehicle to the first vehicle for towing by the first vehicle, a communication path between the first vehicle and the second vehicle, and a processor at the second vehicle. The processor is configured to receive a signal sent from the first vehicle to a communication device at the second vehicle via the communication path, determine an instruction for operating the second vehicle based on the signal, and operate the second drive system and the first drive system based on the instruction to operate the first vehicle and the second vehicle as the series hybrid vehicle.

[0018] In addition to one or more of the features described herein, the processor is further configured to select a charging mode for charging a battery pack of the second vehicle.

[0019] In addition to one or more of the features described herein, the processor is further configured to perform at least one of applying a brake at the second vehicle when a brake is applied at the first vehicle and applying a torque at the second vehicle in response to an acceleration request from the first vehicle.

[0020] In addition to one or more of the features described herein, the processor is further configured to operate the first vehicle and the second vehicle as the series hybrid vehicle when a speed of the second vehicle is greater than a speed threshold.

[0021] In addition to one or more of the features described herein, the processor is further configured to: use data from the second vehicle to determine a speed of the first vehicle when the speed of the first vehicle is not available to the second vehicle.

[0022] In addition to one or more of the features described herein, the processor is further configured to determine a hitch force between the first vehicle and the second vehicle.

[0023] The above features and advantages of the present disclosure, as well as other features and advantages, are apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, advantages, and details appear only by way of example in the following detailed description, which refers to the accompanying drawings, in which:

[0025] Figure 1 Vehicle 10 according to an exemplary embodiment is shown;

[0026] Figure 2 A series hybrid vehicle in an illustrative embodiment is shown;

[0027] Figure 3 Shows a detailed view of the tow tail wire of a series hybrid vehicle in an illustrative embodiment;

[0028] Figure 4 Is a diagram showing data flowing to a following vehicle during the operation of a series hybrid vehicle in an illustrative embodiment;

[0029] Figure 5 Is a diagram showing various modules or programs for operating a following vehicle during the operation of a series hybrid vehicle in an illustrative embodiment;

[0030] Figure 6 Shows a flowchart of a method for operating a series hybrid vehicle in an illustrative embodiment;

[0031] Figure 7 Shows a block diagram illustrating the operation of a fast charging mode;

[0032] Figure 8 Is a block diagram showing the operation of a feedforward algorithm for determining a desired regenerative torque at a second vehicle in an illustrative embodiment;

[0033] Figure 9 Is a block diagram showing the operation of a feedforward operation algorithm at a second vehicle in an alternative embodiment, where the force applied by the second vehicle to the first vehicle cannot be directly measured; and

[0034] Figure 10 Shows a series hybrid vehicle in another illustrative embodiment. Detailed Description

[0035] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding components and features. As used herein, the term module refers to a processing circuit, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) executing one or more software or firmware programs, and a memory, combinational logic circuitry, and / or other suitable components providing the described functionality.

[0036] According to an exemplary embodiment, Figure 1 Shows an embodiment of a vehicle 10 that includes a body 12 that at least partially defines an occupant compartment 14. The body 12 also supports various vehicle subsystems, including a propulsion system 16, and other subsystems for supporting the functions of the propulsion system 16 and other vehicle components, such as a braking subsystem, a suspension system, a steering subsystem, and the like.

[0037] Vehicle 10 can be an electric vehicle (EV), a hybrid vehicle, or any other vehicle. In an embodiment, vehicle 10 is an electric vehicle that includes multiple motors and / or drive systems. Any number of drive units can be included, such as one or more drive units for applying torque to the front wheels (not shown) and / or the rear wheels (not shown). The drive units are controllable to operate vehicle 10 in various operating modes, such as a normal mode, a high-performance mode (where additional torque is applied), all-wheel drive ("AWD"), front-wheel drive ("FWD"), rear-wheel drive ("RWD"), etc.

[0038] For example, propulsion system 16 is a multi-drive system that includes a front drive unit 20 for driving the front wheels and a rear drive unit for driving the rear wheels. The front drive unit 20 includes a front electric motor 22 and a front inverter 24 (e.g., a front power inverter module or FPIM), as well as other components such as a cooling system. The left rear drive unit 30L includes a left rear electric motor 32L and a left rear inverter 34L. The right rear drive unit 30R includes a right rear electric motor 32R and a right rear inverter 34R. The front inverter 24, the left rear inverter 34L, and the right rear inverter 34R (e.g., a power inverter unit or PIM) each convert direct current (DC) power from the high-voltage (HV) battery system 40 into polyphase (e.g., two-phase, three-phase, six-phase, etc.) alternating current (AC) power to drive the front electric motor 22, the left rear electric motor 32L, and the right rear electric motor 32R.

[0039] As Figure 1 shown, the drive system is characterized by separate electric motors. However, the embodiment is not limited thereto. For example, instead of separate electric motors, multiple drives can be provided by a single machine having physically independent multiple sets of windings. In another embodiment, the vehicle can include a single electric motor that drives the wheels through a conventional driveline.

[0040] Also as Figure 1 shown, the drive system is configured such that the front electric motor 22 drives the front wheels (not shown), and the left rear electric motor 32L and the right rear electric motor 32R drive the rear wheels (not shown). However, the embodiment is not limited thereto, as any number of drive systems and / or electric motors can be present at various locations (e.g., an electric motor for driving each wheel, a dual electric motor for each axle, etc.). Additionally, the embodiment is not limited to a dual-drive system, as the embodiment can be used with vehicles having any number of electric motors and / or power inverters.

[0041] In propulsion system 16, the front drive unit 20, the left rear drive unit 30L, and the right rear drive unit 30R are electrically connected to the battery system 40. The battery system 40 may also be electrically connected to other electrical components (also referred to as “electrical loads”), such as vehicle electronics (e.g., via an auxiliary power module or APM 42), heaters, cooling systems, etc. The battery system 40 may be configured as a rechargeable energy storage system (RESS).

[0042] In one embodiment, the battery system 40 includes a plurality of individual battery assemblies, where each battery assembly may be charged independently and may be used to independently power one or more drive systems. For example, the battery system 40 includes a first battery assembly, such as a first battery pack 44 and a second battery pack 46 connected to the front inverter 24. The first battery pack 44 includes a plurality of battery modules 48, and the second battery pack 46 includes a plurality of battery modules 50. Each battery module 48, 50 includes a plurality of individual battery cells (not shown). In various embodiments, one or more of the battery packs may include MODACS (multi-output dynamic adjustable capacity) batteries.

[0043] Each of the front electric motor 22, the left rear electric motor 32L, and the right rear electric motor 32R is a three-phase motor having three-phase motor windings. However, the embodiments described herein are not limited thereto. For example, the motor may be any polyphase machine supplied by a polyphase inverter, and the drive unit may be implemented using a single machine having independent winding groups.

[0044] The battery system 40 and / or the propulsion system 16 includes a switching system having various switching devices for controlling the operation of the first battery pack 44 and the second battery pack 46 and selectively connecting the first battery pack 44 and the second battery pack 46 to the front drive unit 20, the left rear drive unit 30L, and the right rear drive unit 30R. The switching devices can also be operated to selectively connect the first battery pack 44 and the second battery pack 46 to the charging system. The charging system can be used to charge the first battery pack 44 and the second battery pack 46 and / or supply power from the first battery pack 44 and / or the second battery pack 46 to charge another energy storage system (e.g., vehicle-to-vehicle (V2V) and / or vehicle-to-everything (V2X) charging). For example, for V2X charging, power can be output to an external load, a home (operating as backup power for the home), or the utility grid. The charging system includes one or more charging modules. For example, a first on-board charging module (OBCM) 52 is electrically connected to the charging port 54 for charging from and to a DC system or device outside the vehicle 10 (e.g., DC fast charging or DCFC), such as a utility DC power source. The DCFC can be implemented through the charging port 54 and a switching device controlled by a battery control module (e.g., the first OBCM 52) and / or an additional module 66 dedicated to DCFC communication signals. A second on-board charging module (OBCM) 53 can be included for AC on-board charging, including high-power AC charging or V2X charging.

[0045] In an embodiment, the switching system includes a first switching device 60 and a second switching device 62. The first switching device 60 selectively connects the first battery pack 44 to the front inverter 24, the left rear inverter 34L, and the right rear inverter 34R. The second switching device 62 selectively connects the second battery pack 46 to the front inverter 24, the left rear inverter 34L, and the right rear inverter 34R. The switching system also includes a third switching device 64 (also referred to as a "battery switching device") for selectively connecting the first battery pack 44 in series with the second battery pack 46.

[0046] Any of a variety of controllers can be used to control the functions of the battery system 40, the switching system, and the drive units. The controller includes any suitable processing device or unit, and existing controllers can be used, such as a drive system controller, a RESS controller, and / or a controller in the drive system. For example, a controller 65 can be included for controlling the switching and drive control operations discussed herein.

[0047] Vehicle 10 further includes a computer system 55, which includes one or more processing devices 56 and a user interface 58. The computer system 55 can communicate with the charging system controller, for example, to provide commands thereto in response to user input. Various processing devices, modules, and units can communicate with each other via a communication device or system, such as a Controller Area Network (CAN) or Transmission Control Protocol (TCP) bus.

[0048] As shown herein, vehicle 10 is an electric vehicle. In alternative embodiments, vehicle 10 can be an internal combustion engine vehicle, a hybrid vehicle, etc.

[0049] Figure 2 An illustrative embodiment of a series hybrid vehicle 200 is shown. The series hybrid vehicle 200 includes a first vehicle 202 (leading vehicle) and a second vehicle 204 (following vehicle), which are mechanically coupled, typically for towing, and operate synchronously as a single power entity. The first vehicle 202 can be any type of vehicle, such as a gasoline-powered vehicle, a diesel-powered vehicle, an electric vehicle, a hybrid vehicle, etc. The second vehicle 204 is an electric vehicle, such as Figure 1 shown. The first vehicle 202 is mechanically coupled to the second vehicle 204 via a towing hitch 206. The second vehicle 204 is towed by the first vehicle 202 in a flat-tow arrangement, where the wheels of the second vehicle are on the road and rotate during flat-towing. A trailer tail wire 208 can be used to provide a communication path between the first vehicle 202 and the second vehicle 204. In another embodiment, the communication path can be provided through a connection in the towing hitch 206. In another embodiment, the communication path can be a wireless communication path.

[0050] The first vehicle 202 includes a first drive system 210, a first controller 212, a first sensor system 214, and a first communication device 216. The first drive system 210 controls the transfer of torque from the first powertrain of the first vehicle 202 to the wheels of the first vehicle. The first controller 212 includes a processor for controlling the operation of the first vehicle 202. The first sensor system 214 includes one or more sensors for measuring dynamic parameters of the first vehicle 202, which can include but are not limited to the speed of the vehicle, motor speed, motor torque, yaw rate of the first vehicle, front wheel road angle, wheel speed of the first vehicle, etc. The first sensor system 214 provides the dynamic parameters to the first controller 212. The first controller 212 can control the first communication device 216 to send a signal to the second vehicle 204. As disclosed herein, this signal can be used at the second vehicle 204 to control the operation of the second vehicle.

[0051] The second vehicle 204 includes a second drive system 220, a second controller 222, a second sensor system 224, and a second communication device 226. The second drive system 220 controls the transfer of torque from the second powertrain of the second vehicle 204 to the wheels of the second vehicle. The second controller 222 includes a processor for controlling the operation of the second vehicle 204, and the second sensor system 224 may have one or more sensors for measuring dynamic parameters of the second vehicle, which may include but are not limited to the speed of the vehicle, motor speed, motor torque, yaw rate of the second vehicle, front wheel road angle, wheel speed of the second vehicle, etc. The second controller 222 communicates with the second communication device 226. The second communication device 226 is configured to receive a signal from the first communication device 216 and provide the signal to the second controller 222. The second controller 222 may perform an operation at the second vehicle 204 based on the signal.

[0052] The first controller 212 and the second controller 222 may include processing circuitry, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) that executes one or more software or firmware programs, and memory, combinational logic circuitry, and / or other suitable components that provide the described functionality. The first controller 212 and the second controller 222 may include a non-transitory computer-readable medium storing instructions that, when processed by one or more processors of the first controller 212 and the second controller 222, implement a method for coordinating the operation of the first vehicle 202 and the second vehicle 204 during a traction operation according to one or more embodiments detailed herein.

[0053] When the first vehicle 202 and the second vehicle 204 are mechanically hitched or mechanically coupled, the first vehicle may provide commands or instructions to the second vehicle via a communication path to control its operation. Thus, the first drive system 210 and the second drive system 220 may thus operate as a single power entity of the series hybrid vehicle 200. For example, when the first vehicle 202 is accelerating, the second vehicle 204 may provide positive propulsion force, which may assist the acceleration of the first vehicle. Additionally, when the first vehicle 202 has actuated its braking system, the second vehicle 204 may provide deceleration torque. Further, when the second vehicle 204 is combined with the first vehicle 202 in the series hybrid vehicle 200, the second vehicle 204 may choose to operate in a regenerative mode to charge its battery pack.

[0054] Figure 3Shows a detailed view of the tow tail wire 208 of the series hybrid vehicle 200 in an illustrative embodiment. The tow tail wire 208 includes a leading vehicle coupler 302 and a following vehicle coupler 304, and wires extend between the leading vehicle coupler 302 and the following vehicle coupler 304. These wires include a left wheel indicator wire 306, a right wheel indicator wire 308, a tail light indicator wire 310, and a ground wire 312. When the left turn or left brake of the leading vehicle is activated, a signal is sent through the left wheel indicator wire 306. When the right turn or right brake of the leading vehicle is activated, a signal is sent through the right wheel indicator wire 308. When the tail lights of the leading vehicle are activated, a signal is sent through the tail light indicator wire 310.

[0055] Figure 4 Figure 400 shows the data flowing to the following vehicle during the operation of the series hybrid vehicle 200 in an illustrative embodiment. Figure 400 shows the second controller 222 and the second sensor system 224 of the following vehicle. The second sensor system 224 can provide the status data of the following vehicle. Figure 400 also shows the leading vehicle data 402, the route data 404, and the energy map data 406. The leading vehicle data 402 is provided by the first vehicle 202 and includes data such as, but not limited to, acceleration requests, braking requests, the speed of the leading vehicle, the large selection or gear state of the leading vehicle, and the braking state of the leading vehicle.

[0056] The route data 404 can be provided by a remote server and includes route planning, weather data, altitude data, and previously learned performance data. The route data 404 can be provided to the energy map. The energy map locates charging stations along the route (e.g., energy map data 406) and provides these locations to the second controller 222. The second controller 222 operates at the Advanced Driver Command Interpreter Module (ADCI 408). The ADCI is a program or application that controls the operation of the following vehicle during a towing scenario and provides torque commands to the following vehicle based on the data provided to the second controller 222.

[0057] Figure 5 Figure 500 shows the various modules or programs for operating the following vehicle during the operation of the series hybrid vehicle 200 in an illustrative embodiment. The modules include the ADCI 408, the Mode Status Module 502, the Driver Command Interpreter (DCI) 504, the Motor Controller 506, the Safety Limit Module 508, the Comparator 510, and the Display 512.

[0058] The ADCI 408 receives as Figure 4The data shown and outputs a desired torque command to be applied at the following vehicle. The desired torque command can be selected to optimize the fuel economy and / or range of the leading vehicle. The mode status module 502 provides the current operating mode of the following vehicle (such as being actively towed, driving, etc.) to the ADCI 408. The ADCI 408 outputs the desired torque command to the DCI 504 and the safety limit module 508. The DCI 504 determines the motor command for the desired torque. The safety limit module 508 keeps the applied torque within the torque safety limit of the following vehicle. The DCI 504 provides the motor command to the motor controller 506, and the motor controller 506 applies the motor command to the motor. The comparator 510 compares the desired torque with the applied torque, and the difference is provided as feedback to the ADCI 408.

[0059] Figure 6 FIG. 600 is a flow chart showing a method for operating a series hybrid vehicle 200 in an illustrative embodiment. At block 602, the user inserts the tow bar 208 between the first vehicle 202 and the second vehicle 204 and initializes the application operating at the ADCI 408.

[0060] The application can prompt for the profile of the leading vehicle. If the leading vehicle is recognized, the profile can be a stored profile. Otherwise, a new profile can be created. After the profile has been established, the following vehicle establishes a communication link to the leading vehicle (e.g., via the tow bar 208). The following vehicle then prompts the user for an appropriate towing mode. Different towing modes provide the user with flexibility in how to charge their battery while being towed.

[0061] At block 604, the wheels of the second vehicle are unlocked (i.e., its steering lock and parking brake) to allow free rotation. Then, the second vehicle 204 flashes its headlights (or provides an audible tone) to indicate to the leading vehicle that the following vehicle is ready to be towed. The second vehicle 204 can display a message at the display to confirm the selected mode. The display can be a head-up display (HUD).

[0062] At block 606, the brake signal of the first vehicle is queried at the second vehicle 204. When the first vehicle 202 applies its brakes, a brake signal is sent. If the brake signal is detected (i.e., a signal along one or more of the left wheel indicator line 306 and the right wheel indicator line 308), the method proceeds to block 608. At block 608, the second vehicle 204 enters a braking mode that applies braking logic. In one embodiment, a wheel speed sensor can measure the wheel rotational speed, which can be used to select between a regenerative mode and an electric motor braking mode. In an embodiment, regenerative braking is applied unless the state of charge (SOC) of the battery pack is greater than the commanded SOC.

[0063] Return to block 606. If no brake signal from the first vehicle 202 is detected, the method proceeds to block 610. At block 610, the taillight signal of the leading vehicle is queried to ensure towing safety. The first vehicle 202 turns on its headlights when operating as part of the series hybrid vehicle 200. If no taillight signal is detected, the method proceeds to block 612. The absence of a taillight signal (and no brakes) indicates that the first vehicle has become disconnected. At block 612, the second vehicle 204 is placed in an idle state. The following vehicle can flash its headlights in a selected pattern to signal to the driver of the leading vehicle that the following vehicle is in an idle state. Return to block 610. If a taillight signal is detected, the method proceeds to block 614. Although the idle decision at block 606 is discussed herein as being conveyed by a headlight signal, in other embodiments, any suitable signal (wired or wireless) can be used for communication between the first vehicle 202 and the second vehicle 204 to determine whether to enter an idle state at the second vehicle.

[0064] At block 614, the wheel speed of the second vehicle 204 is measured. If the wheel speed v x of the following vehicle is less than the speed threshold v thres , (v x < v thres ), the method proceeds to block 612. In this case, the second vehicle 204 decelerates to reverse (v thres > v x > 0) or reverse (v x < 0). Accordingly, the second vehicle 204 is allowed to idle so as not to apply any torque during these movements. Return to block 614. If the wheel speed is greater than or equal to the speed threshold (v x > v thres ), the method proceeds to block 616.

[0065] At block 616, the following vehicle is placed in a hybrid operation mode. In the hybrid operation mode, the second vehicle 204 provides power to the series hybrid vehicle 200 upon instruction from the first vehicle 202. The following vehicle reduces the power consumed by the leading vehicle by, for example, providing propulsion on its own power and providing braking, etc. Additionally, the following vehicle can select a charging mode for charging its battery pack based on the movement provided while being towed. The charging mode can be, for example, a fast charging mode, a hybrid charging mode, a hybrid maximum mode, and a standard charging mode.

[0066] The fast charging mode allows the second vehicle 204 to charge as quickly as possible. This mode includes charging using regeneration until the vehicle is fully charged. The charging rate of the battery is related to the speed of the vehicle.

[0067] The hybrid charging mode includes maintaining the state of charge (SOC) of the battery pack of the second vehicle at a target minimum level. If the SOC is less than the target minimum level, the second vehicle 204 operates in a regenerative mode. Otherwise, torque is applied at the second vehicle 204 in a torque feedforward mode.

[0068] The hybrid maximum mode preferentially provides propulsion at the second vehicle 204 until the SOC of the battery pack drops to the target minimum level. The hybrid maximum mode is the same as the hybrid charging mode, except that the target minimum level is lower and the torque feedforward mode includes a higher torque application setpoint.

[0069] The standard mode includes operating in a regenerative mode only when conditions permit (such as when braking is applied at the second vehicle 204).

[0070] When the following vehicle is ready to be unhitched, the user closes the application, unhitches the towing hitch, and disconnects the trailer tail wire 208.

[0071] Figure 7 A block diagram 700 illustrating the operation of the fast charging mode is shown. The block diagram 700 includes a look-up table 702 and a stability controller 704. The vehicle speed 706 and the battery SOC 708 are input to the look-up table 702 in order to output a desired regenerative power 710 or an available regenerative power. The regenerative operation includes ramping up to a maximum regenerative power based on the speed of the following vehicle. The maximum regeneration rate is limited based on the SOC of the battery pack. The desired regenerative power 710 is used to determine a desired regenerative torque 712. In one embodiment, the stability controller 704 may be used to determine the desired regenerative torque 712 based on the desired regenerative power 710.

[0072] Figure 8 A block diagram 800 showing the operation of a feedforward algorithm for determining the desired regenerative torque at the second vehicle 204 in an illustrative embodiment is shown. The feedforward algorithm includes a traction angle sensor fusion module 802, a vehicle resistance estimation module 804, a hybrid torque look-up table 806, and a traction stability controller 808.

[0073] The vehicle yaw rate 810, the front wheel angle 812, and the wheel speed 814 of the second vehicle 204 are input to the traction angle sensor fusion module 802, and the traction angle sensor fusion module 802 outputs a vehicle traction angle 816. The vehicle traction angle is the angle between the first vehicle 202 and the second vehicle 204. The determination of the traction angle may include a rough measurement obtained from the first vehicle 202. In another embodiment, a front camera of the second vehicle 204 may be used to determine the traction angle. The traction angle can be used to limit torque for safety purposes. For example, the higher the traction angle, the lower the maximum positive torque that can be applied by the second vehicle 204 to the first vehicle 202.

[0074] The vehicle roll and pitch 818, as well as the vehicle body speed 820, are input into the vehicle resistance estimation module 804, and the vehicle resistance estimation module 804 outputs the estimated vehicle resistance 822 of the second vehicle. The vehicle resistance can be used to estimate the sum of the longitudinal forces acting on the second vehicle, including drag, rolling resistance, road grade, etc. An online machine learning system, a calibrated look-up table, or other methods can be used to calculate the resistance.

[0075] The vehicle traction angle 816, the estimated vehicle resistance (tractive force) 822, the SOC 824 of the battery, and the current hybrid mode 826 of the vehicle are input into the hybrid torque look-up table 806, and the hybrid torque look-up table 806 outputs the regenerative torque 828. When additional traction stability is required, the regenerative torque 828 can optionally be modified by the traction stability controller 808 to determine the desired regenerative torque 830.

[0076] The energy map data 406 and / or the route data 404 can be provided to the hybrid torque look-up table 806. The decision regarding the regenerative torque 828 can be based on the vehicle conditions (e.g., the vehicle traction angle 816, the estimated vehicle resistance 822), as well as the energy map data 406 and / or the route data 404, to provide the locations where peak regenerative efficiency is required and / or the peak load conditions where a given percentage of the free SOC is required for propulsion purposes.

[0077] Figure 9 is a block diagram 900 showing the operation of a feed-forward operation algorithm at the second vehicle in an alternative embodiment, where the force applied by the second vehicle 204 to the first vehicle 202 cannot be directly measured. The block diagram 900 includes Figure 8 the traction angle sensor fusion module 802, the vehicle resistance estimation module 804, the hybrid torque look-up table 806, and the traction stability controller 808. The block diagram 900 also includes a hitch force estimation module 902, a desired hitch force calculator 904, and a torque arbiter 906.

[0078] The traction force estimation module 902 receives as inputs the wheel speed 814, vehicle roll and pitch 818, and body speed 820 of the second vehicle 204, as well as the motor torque 908 of the second vehicle 204. The hitch force estimation module 902 calculates the hitch force between the first vehicle 202 and the second vehicle 204 and provides it to the vehicle resistance estimation module 804, which uses the hitch force to calculate the estimated vehicle resistance 822. The hybrid torque lookup table 806 provides the commanded torque to the desired hitch force calculator 904. The desired hitch force calculator 904 calculates a torque regeneration command based on the hitch force (from the hitch force estimator) and the commanded torque suitable for obtaining the desired hitch force. For example, a compressive hitch force between the first vehicle 202 and the second vehicle 204 is undesirable because it causes instability. The torque regeneration command from the desired hitch force calculator and the torque regeneration command from the traction stability controller 808 are input to the torque arbiter 906, which outputs the motor torque regeneration command 908.

[0079] Figure 10 A series hybrid vehicle 1000 in another illustrative embodiment is shown. The series hybrid vehicle 1000 includes a first vehicle 202 (the leading vehicle), a second vehicle 204 (the first following vehicle), and a third vehicle 1002 (the second following vehicle). The second vehicle 204 is mechanically coupled to the first vehicle 202 for towing, and the third vehicle 1002 is mechanically coupled to the second vehicle 204 for towing. The second vehicle 204 and the third vehicle 1002 are electric vehicles. The trailer tail line 208 provides a communication path between the first vehicle 202 and the second vehicle 204. The second trailer tail line 1004 provides a communication path between the second vehicle 204 and the third vehicle 1002. The first vehicle 202 can provide commands or instructions to the second vehicle 204 and the third vehicle 1002. Thus, the third vehicle 1002 can operate similarly to the second vehicle 204 during a towing operation. In another embodiment, additional electric vehicles can be attached behind the third vehicle 1002 and operate similarly.

[0080] The terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. Unless the context clearly dictates otherwise, the term "or" means "and / or". References throughout the specification to "aspect" mean that a particular element (e.g., feature, structure, step, or property) described in connection with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. Additionally, it should be understood that the described elements can be combined in any suitable manner in the various aspects.

[0081] When an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as “directly on” another element, intervening elements are absent.

[0082] Unless otherwise stated herein, all test standards are the latest standards in effect as of the filing date of this application, or, if priority is claimed, as of the filing date of the earliest priority application in which the test standard is cited.

[0083] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0084] Although the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted for its elements without departing from its scope. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the disclosure without departing from its basic scope. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that it will include all embodiments falling within its scope.

Claims

1. A method for a first vehicle to tow a second vehicle, comprising: Establishing a communication path between the second vehicle and the first vehicle, the first vehicle having a first drive system; Sending, via the communication path, a signal from the first vehicle to the second vehicle indicating an instruction for operating the second vehicle; And Based on the instruction for operating the first vehicle and the second vehicle as a series hybrid vehicle, operating a second drive system of the second vehicle and the first drive system of the first vehicle.

2. The method according to claim 1 further comprises: Selecting a charging mode for charging a battery pack of the second vehicle.

3. The method according to claim 1, further comprising at least one of the following: (i) applying a brake at the second vehicle when a brake is applied at the first vehicle; and (ii) applying torque at the second vehicle in response to an acceleration request from the first vehicle.

4. The method according to claim 1 further comprises: Operating the first vehicle and the second vehicle as the series hybrid vehicle when a speed of the second vehicle is greater than a speed threshold.

5. The method according to claim 1 further comprises: Using data from the second vehicle to determine a speed of the first vehicle when the speed of the first vehicle is not available to the second vehicle.

6. An electric vehicle, comprising: An electric drive system; A communication device for communicating along a communication path between the electric vehicle and a first vehicle, the first vehicle having a first drive system, the first vehicle being coupled to the electric vehicle for towing the electric vehicle; A processor configured to: Receive a signal transmitted from the first vehicle to the communication device; Determine an instruction for operating the electric vehicle according to the signal; And Based on the instruction for operating the first vehicle and the electric vehicle as a series hybrid vehicle, operating the electric drive system of the electric vehicle and the first drive system of the first vehicle.

7. The electric vehicle according to claim 5, wherein, The processor is further configured to select a charging mode for charging a battery pack of the electric vehicle.

8. The electric vehicle according to claim 5, wherein, The processor is further configured to perform at least one of the following: (i) applying a brake at the electric vehicle when a brake is applied at the first vehicle; and (ii) applying torque at the electric vehicle in response to an acceleration request from the first vehicle.

9. The electric vehicle according to claim 5, wherein, The processor is further configured to operate the first vehicle and the electric vehicle as the series hybrid vehicle when a speed of the electric vehicle is greater than a speed threshold.

10. The electric vehicle according to claim 5, wherein, The processor is further configured to use data from the electric vehicle to determine a speed of the first vehicle when the speed of the first vehicle is not available to the electric vehicle.

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