Patent Publication Number: US-2023145383-A1

Title: Electrified vehicle trailer charging at single vehicle charging stalls

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates in general to aiding a driver in charging one or more battery units of an electrified passenger vehicle which is towing a trailer with a trailer-mounted battery unit, and, more specifically, to guiding the trailer to a parking location in a charging stall of a charging facility which requires decoupling of the trailer from the vehicle for recharging. 
     The level of battery capacity conventionally available on electrified vehicles has led to challenges in providing sufficiently long driving distances (i.e., driving range) before needing to be recharged. In addition to providing adequate driving range, it is desirable that when an electric vehicle is recharged that the time required to reach a desired state of charge be kept short. 
     Improvements in electrified vehicles have enabled them to be employed in many types of vehicle usage applications, such as towing trailers for expanded cargo capacity or for camping. Such trailers may include supplemental batteries to supply electrical power for use by electrical devices in the trailer and/or as supplemental power for the towing vehicle. In addition, trailers can also be deployed with the sole purpose of providing a secondary battery to supply power to the electrified vehicle which results in extending the driving range before a recharge is needed. 
     Undertaking a recharging operation while towing a trailer having a secondary battery which will also be recharged leads to added considerations such as 1) the need for a layout at a charging station that accommodates the length of a combined vehicle and trailer, 2) the need for a placement of chargers which can reach the charge ports of the vehicle and trailer, 3) availability of chargers that can deliver charging rates meeting the requirements of the driver, 4) checking for the availability of recharging time at a charging station which is able to accommodate the vehicle/trailer combination and charging objectives, and 5) navigating the vehicle and trailer into a corresponding parking spot once a charging station has been selected. Some vehicles or trailers may have more than one usable charge port or may have multiple charging modes (e.g., charging rates and/or the ability to pass through a charging current to another battery unit, such as from the vehicle to the trailer-mounted battery). Because of the large number of interacting options, it becomes difficult for the driver to easily and conveniently select and implement an optimal recharging task. 
     A public infrastructure supporting battery charging has been growing as increasing numbers of electric vehicles have come into service for both commercial and personal use. The footprint of parking spaces (i.e., stalls) and the charger outlets arranged beside them are mostly configured for single, passenger-sized vehicles in order to work with the most prominent style of electric vehicles on the road. Perpendicular or angled parking stalls with a single car length may have a charger outlet placed adjacent to an end of the stall opposite from the stall entrance. A smaller number of publicly available charging facilities may include drive-through stalls which are longer in order to accommodate trucks or commercial vehicles, but these may be less readily accessible to a driver of an electrified vehicle which is towing a trailer. Therefore, it would be desirable to make use of charging facilities of the type set up for passenger vehicles alone to instead recharge an electrified trailer and/or electrified passenger vehicle together. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, an electrified vehicle comprises a rechargeable onboard battery unit storing electrical power for a traction motor used to move the vehicle. The vehicle has a trailer interface configured to communicate with a trailer controller in a trailer that includes a rechargeable trailer-mounted battery unit and a drive control system for independently moving the trailer during parking in a selected charging stall to charge the trailer-mounted battery. The vehicle has at least one sensor configured to characterize the selected charging stall by performing a sensor sweep while proximate to the selected charging stall. The vehicle has a vehicle controller configured to generate a selection of the selected charging stall and to generate a map of the charging stall in response to the sensor sweep. The vehicle controller is configured to calculate a drive sequence of the trailer from a predetermined location where the trailer is unhitched from the vehicle to a target position in the selected charging stall, and to transmit the drive sequence to the trailer controller. 
     In another aspect of the invention, a method is provided for charging a trailer-mounted battery unit in a trailer being towed by an electrified passenger vehicle. A charging stall is selected at a charging station, wherein the selected charging stall has a size configured for a single vehicle and has a respective charger outlet arranged proximate to the selected charging stall. The passenger vehicle is situated adjacent to the selected charging stall such that at least one sensor of the passenger vehicle is in a position for remotely sensing the selected charging stall. A sensor sweep is performed with at least one sensor while proximate to the selected charging stall. A map is generated of the charging stall in response to the sensor sweep. A drive sequence of the trailer is calculated from a mapped predetermined location where the trailer is unhitched from the vehicle to a mapped target position within the selected charging stall. The drive sequence is transmitted from the passenger vehicle to a trailer controller in the trailer via a trailer interface. A drive control system in the trailer is activated for independently moving the trailer to the mapped target position within the selected charging stall in order to charge the trailer-mounted battery. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic view of an electrified vehicle towing a trailer with a trailer-mounted battery unit. 
         FIG.  2    is a schematic view of an example layout of a charging station with single-vehicle charging stalls. 
         FIG.  3    is an overhead view of a charging station layout having pull-through lanes to accommodate longer vehicles. 
         FIG.  4    is an overhead view of an electrified vehicle towing a trailer at a charging station with single-vehicle charging stalls, wherein the vehicle and trailer are being charged without uncoupling the trailer. 
         FIG.  5    is a schematic diagram showing an electrified trailer which includes onboard sensors and an independent drive system capable of moving the trailer short distances into or out of a parking space. 
         FIG.  6    is an overhead view of an electrified vehicle performing a sensor sweep to characterize a charging stall. 
         FIGS.  7 ,  8 , and  9    are overhead views depicting a sequence of automatic parking of the trailer into a scanned charging stall wherein  FIG.  7    shows a starting position of an unhitched trailer and a calculated path for the trailer,  FIG.  8    shows the trailer executing the path, and  FIG.  9    shows the electrified vehicle moving into a separate charging stall while the trailer charges in the selected stall. 
         FIG.  10    is a schematic block diagram showing a vehicle and trailer according to an embodiment of the invention. 
         FIG.  11    is a flowchart showing one preferred method according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG.  1    shows an electrified vehicle  10  (often referred to as a battery-electric vehicle or BEV) configured as an electric pickup truck. Vehicle  10  has an onboard rechargeable battery unit  11  which stores electrical power for a traction motor (not shown) to propel vehicle  10 . The traction motor may comprise an electric machine mechanically coupled to a gearbox which may include a differential. The electric machine may also act as a generator during deceleration to recover energy that would normally be lost as heat in a friction braking system. 
     Battery unit  11  may be comprised of a multi-cell battery which provides a high voltage, direct current (DC) output. A contactor module may selectably connect battery unit  11  with a high-voltage bus (not shown). A power electronics module (not shown) controls operation of the electric machine and provides the ability to bi-directionally transfer energy between battery unit  11  and the electric machine. The power electronics module may convert the DC voltage to a three-phase AC current to operate the electric machine. In a regenerative mode, the power electronics module may convert the three-phase AC current from the electric machine acting as a generator to a DC voltage for recharging battery unit  11 . 
     Vehicle  10  is configured to recharge battery unit  11  from external power sources using one or more charge ports  12  and  13 . External power sources may include electrical outlets at private or public locations. Electric vehicle supply equipment (EVSE) for connecting to a vehicle’s charging port may include a charger unit at a charging station (i.e., a location having parking stalls or spaces each provided with one or more charger units). A charging station serving a plurality of electrified cars and trucks may be connected to an electrical power distribution network or grid as provided by an electric utility company and may be managed by electronic control systems enabling users to reserve a time period and charger outlet for their use, as described in patent application publication U.S. 2020/0148068A1 and in patent U.S. 11,001,161, which are both incorporated herein by reference.  FIG.  2    shows a charging station  20  having parking spaces  21 - 23  which each has a respective charger unit  24 - 26 , respectively, arranged for use by electric vehicles parked in the spaces. 
     The EVSE and control systems of the charging station may regulate and manage the transfer of energy between a power source and vehicle  10 . Charge ports  12  and  13  may be any type of port configured to transfer power from EVSE to vehicle  10 . In some embodiments, charge ports  12  and  13  may be electrically coupled to an on-board power conversion module which provides proper voltage and current levels to battery unit  11 . An EVSE connector may have pins that mate with corresponding recesses of charge port  12  or  13 . Alternatively, various components described as being electrically coupled or connected may transfer power using a wireless inductive coupling. The use of EVSE for charging BEV batteries is described in patent application publication U.S. 2020/0369168A1, which is incorporated herein by reference. 
     Returning to  FIG.  1   , vehicle  10  is hitched together with trailer  14  which includes a respective battery unit  15 . The use of trailer  14  may be primarily for the purpose of carrying additional battery capacity for vehicle  10 , in which case a trailer hitch  16  may provide both mechanical and electrical connections. In addition to the extra battery capacity, trailer  14  may additionally provide a supplemental cargo space. With or without providing supplemental battery power to vehicle  10 , trailer  14  could be configured as a camper or other functional unit which uses the trailer battery to power trailer-mounted devices (e.g., electrical appliances). For charging trailer-mounted battery unit  15 , trailer charge ports  17  and  18  are coupled to battery unit  15 . 
       FIG.  3    shows a pull-through layout of a charging station  27  having charging outlets deployed adjacent a plurality of pull-through lanes, such as a charging outlet  28  for a corresponding lane  29 . Availability of a pull-through lane simplifies charging of trail-mounted battery units, but such an arrangement may be difficult to find when it is needed. Instead, a driver of a combined electric vehicle and trailer may often need to stop for recharging at a charging station with the more commonplace layout which has single-vehicle charging stalls. For the trailer to remain coupled to the passenger vehicle during charging, however, multiple charging stalls and/or access aisles to the stalls may be blocked. Even if such a use of a charging facility is allowed, availability for reserving access to the required number of adjacent stalls may be much more limited. Therefore, uncoupling of a trailer during charging would be desirable. However, many drivers are not comfortable with the maneuvers needed to back a trailer into a stall. Some trailers are available with self-contained drive motors capable of moving a trailer a short distance for parking, sometimes also including sensors for detecting and avoiding obstacles while moving. However, such sensors would be seldom used. To avoid excessive cost, trailer sensors have tended to have low resolution. Therefore, significant driver/user intervention has been needed, and fully automatic operation has been elusive. 
       FIG.  5    depicts trailer  14  in more detail. A trailer body/chassis  30  supports wheels  31  and  32  which can be driven by electric motors  33  and  34 , respectively, using power from battery unit  15 . A trailer controller  35  communicates with a controller in the towing vehicle via a communication channel  36  (wired or wireless) to receive data and commands for driving motors  33  and  34  to propel trailer  14  along a desired path. 
     Trailer  14  has a coupling/jack system  16  for hitching and unhitching trailer  14  to/from the towing vehicle. System  16  can be fully manual or can include a robotic arm  37  controlled by an actuator  38  for automatically engaging or disengaging a ball coupling and a motorized jack unit  40  for automatically extending or retracting a jack wheel. Controller  40  is connected to actuator  38  and unit  40  for coordinating the hitching or unhitching in cooperation with driver commands received from a vehicle controller via communication channel  36 . 
     Trailer  14  may further include a plurality of sensors for monitoring the surrounding environment and obstacles. For example, sensors  41 ,  42 , and  43 , which are coupled to trailer controller  35 , may be comprised of radar transceiver units, cameras, lidar sensors, acoustic/microphone sensors, and/or ultrasonic units. Data provided by sensors  41 - 43  can be transmitted to the vehicle controller to assist in mapping a charging stall and/or can be used by trailer controller  35  to prevent collision with nearby (e.g., moving) objects when trailer  14  moves autonomously and/or to monitor automatic operation of coupling/jack system  16 . 
     A procedure for using a charging station or other facility to charge a trailer-mounted battery unit may begin with identifying or selecting a charging stall to be used by the trailer. A charging stall can be selected remotely using a reservation scheme as described in patent application publication U.S. 2020/0148068A1 and in patent U.S. 11,001,161, for example. Alternatively, a charging stall can be selected without a reservation by manually inputting the selection using a user interface in the vehicle. For example, the driver may navigate the vehicle to approach a desired charging stall such that the charging stall become visible within a camera view from a vehicle-mounted camera. By displaying the camera view on a touchscreen display, the driver can tap on the display at a spot corresponding to the desired charging stall. 
     Once a selection for a particular charging stall is available, remote sensing is used to map an absolute or relative location of the selected charging stall. As shown in  FIG.  6   , a row of charging stalls  45  with corresponding charger outlets (e.g., charger outlets  46 - 48 ) is laid out as single-vehicle stalls. A selected or target stall  50  has been selected for use to charge trailer  14 . Using one or more remote sensing units, vehicle  10  performs a sensor sweep  51  of an area around and including selected stall  50  with vehicle  10  positioned proximate to stall  50 . Depending upon the capabilities of the vehicle-mounted sensors (and potentially the capabilities of any trailer-mounted sensors being used), sensor sweep  51  may be conducted from a fixed position or while moving. Features detected by sensor sweep  51  may include stall boundaries (e.g., painted lines on the ground detected optically using a camera, or a curb detected by reflection of a radar or ultrasonic pulse), the placement and configuration of a charger unit (e.g., detected optically), vehicles parked in adjacent stalls, and the like. Data from sensor sweep  51  can be compiled as a map fixing the features of the stall to a position of the vehicle and/or trailer. Based on the map, a vehicle controller examines the stall boundaries and the location of the charger unit to identify a target position for parking the trailer to be charged. 
     As shown in  FIG.  7   , vehicle  10  tows trailer  14  to a predetermined location  55  to be used as an entrance into selected charging stall  50 . At predetermined location  55 , trailer  14  is uncoupled from vehicle  10  (either manually or automatically). The map compiled by a vehicle controller includes a representation of stall side lines  52  and  53  and a front boundary (e.g., curb)  54 . The map also defines location  55  and a drive path  56  to be traversed by trailer  14  to move it from location  55  to the target position when it can be hooked up with charger unit  47 . 
     A sequence of driving commands which are calculated by a vehicle controller are transmitted to a trailer controller.  FIG.  8    shows trailer  14  being self-propelled using differential wheel rotation to execute a curve  57  along drive path  56  to target position  58  in selected stall  50 .  FIG.  9    shows trailer  14  backed into selected stall  50  and connected to charger unit  47 , while uncoupled vehicle  10  separately moves along a path  60  into another charging stall. Alternatively, vehicle  10  could temporarily drive away in order perform other errands while trailer  14  is charging. 
       FIG.  10    is a block diagram showing one embodiment of a vehicle, trailer, and remote reservation system. Vehicle  10  has a controller  70  (e.g., electronic module) with a programmable microprocessor and a program memory for storing software programs to perform the procedures described herein. Controller  70  may communicate with offboard resources using a wireless transceiver  71 . Cellular data communications or other wireless data protocols can be used by transceiver  71  to communicate with a cloud network  72  containing a server or other components for creating a reservation service. Vehicle  10  has a human machine interface (HMI)  73  for interacting with a driver during various steps in a process of selecting a charging stall and parking a trailer in the selected stall. HMI  73  may include a touchscreen display. The HMI can additionally or alternatively include a touchscreen or other control elements mounted on trailer  14  and/or a smartphone or other mobile computing device. In addition to accessing reservation service  72  and/or manually identifying a charging stall, the touchscreen display can be used to provide messages to a driver relating to any manual steps needed during hitching or unhitching trailer  14 . Sensors  74  in vehicle  10  may include radar transceivers, optical or infrared cameras, lidar, acoustic/microphone sensors, and/or ultrasonic sensors. 
     Vehicle  10  has an interface  75  connected to vehicle controller  70  providing a communication channel  82  to an interface  81  in trailer  14  which is connected to a trailer controller  80 . Channel  82  may be a wireless link according to a known standard such as Bluetooth ® , WiFi, or ultra-wideband (UWB). In addition to communication channel  82 , vehicle  10  and trailer  14  are connected mechanically and/or electrically by a hardware connection  83 . 
     Trailer  14  includes motors  84  and  85  coupled to wheels on opposite sides of trailer  14 . Motors  84  and  85  are controlled independently using commands in a drive sequence received by controller  80  from vehicle  10  over channel  82  in order to steer trailer  14  along a desired path. Actuators  86  (e.g., a robotic arm for manipulating the hitch mechanism and a servomechanism for lowering/raising a jack wheel) may be provided in association with a trailer hitch mechanism and a jack wheel unit for embodiments with automatic hitching/unhitching of trailer  14 . 
       FIG.  11    provides a flowchart for one embodiment of a method of the invention. In step  90 , a charging stall is selected for use in charging the trailer. The selection can include enrolling a reservation of the selected stall or can include a manual selection of a charging stall by the driver of the vehicle. In step  91 , the vehicle is situated at (i.e., arrives at) the selected charging stall while towing the trailer. The vehicle/trailer combination can stop proximate to the selected charging stall or can drive by (i.e., bypass) the selected stall as it performs a sensor sweep in step  92  to create a map defining the selected stall. Based on the compiled map, the vehicle then proceeds to and stops at a predetermined (mapped) position at which the trailer becomes registered at the entrance to the selected charging stall (i.e., aligned with the selected stall such that the self-contained driving system on the trailer can easily navigate to the target location). 
     In step  93 , a controller in the vehicle calculates a drive sequence to be used by the trailer to park at the target location. The drive sequence may include 1) commands for a robotic arm and/or jack-wheel servomechanism in order to automatically uncouple from the vehicle, and 2) parking commands specifying rotations of the trailer wheels which will move the trailer to the target position. In step  94 , the drive sequence is transmitted to the trailer controller. The trailer is unhooked from the vehicle in step  95 . Alternatively, the trailer could be uncoupled before transmitting the drive sequence in step  94  provided that the communication channel is wireless. 
     In step  96 , the trailer self-drives into the selected stall and stops when the target position is obtained. The trailer can then be hooked up to the corresponding charger unit and charging is commenced. 
     After charging, the trailer is unhooked from the charger unit. In order to re-couple to the vehicle, the drive sequence that was originally used to park the trailer at the target position can be executed in reverse to move the trailer back to the same position where it was unhitched from the vehicle. Then the vehicle can be backed up to the trailer and the two can be re-hitched (either manually or automatically using appropriate commands to the robotic arm and/or jack-wheel servomechanism).