Abstract:
A method of operating an electric vehicle charging station. The charging station may include a console housing components configured to receive current from an electric grid and convert the current to a form adapted to be received by the electric vehicle. The method may include transferring heat from the components in the console to air flowing through the console to form heated air, and directing the heated air from the console into a duct fluidly coupled to the console. The method may further include exhausting the heated air from the duct to a location remote from the console.

Description:
TECHNICAL FIELD 
     The current disclosure relates to systems and methods for harnessing heat produced during electric vehicle charging. 
     BACKGROUND 
     An electric vehicle (EV), also referred to as an electric drive vehicle, uses an electric motor for propulsion. Electric vehicles may include all-electric vehicles where the electric motor is the sole source of power, and hybrid electric vehicles that include an auxiliary power source in addition to the electric motor. In an electric vehicle, energy may be stored in one or more batteries (located in the electric vehicle) to power the electric motor. When the stored energy decreases, the batteries may be charged (or recharged) by connecting the vehicle to an external charger. As current flows, components in the external charger and the battery may get heated due to joule heating. The vehicle cooling system may cool the components of battery, and an air handling system may force air past the heated components of the external charger to cool them. Typically, the heated air is exhausted into the atmosphere thereby wasting the heat extracted from the components. An increase in efficiency and cost savings may be achieved by harnessing the waste heat produced during charging to do useful work. 
     SUMMARY 
     Embodiments of the present disclosure relate to, among other things, systems and methods for harnessing heat produced during electric vehicle charging. Each of the embodiments disclosed herein may include one or more of the features described in connection with any of the other disclosed embodiments. 
     In one embodiment, a method of operating an electric vehicle charging station is disclosed. The charging station may include a console housing components configured to receive current from an electric grid and convert the current to a form adapted to be received by the electric vehicle. The method may include transferring heat from the components in the console to air flowing through the console to form heated air, and directing the heated air from the console into a duct fluidly coupled to the console. The method may further include exhausting the heated air from the duct to a location remote from the console. 
     In another embodiment, a method of operating a charging station of an electric bus is disclosed. The charging station may include a console housing one or more components configured to convert AC current from an electric grid to DC current for the electric vehicle, and a charge head assembly configured to electrically couple with the electric bus. The method may include transferring heat from the one or more components in the console to a coolant flowing through the console. The method may also include directing the coolant to a location remote from the console to dissipate the heat the location. 
     In yet another embodiment, a charging station for an electric vehicle is disclosed. The charging station may include a charging head assembly configured to interface and form an electrical connection with an electric vehicle. The station may also include a console electrically coupled to the charging head assembly. The console may house components configured to receive current from an electric grid and convert the current to a form that may be received by the electric vehicle. The console may further be configured to direct a flow of air therethrough to absorb heat from the components and form heated air. The station may also include a duct connected to the console to receive the heated air from the console and discharge the heated air to a location remote from the console. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure and together with the description, serve to explain the principles of the disclosure. 
         FIG. 1  is an illustration of an exemplary electric bus according to the current disclosure; 
         FIG. 2A  is a bus stop with an exemplary charging station; 
         FIG. 2B  illustrates a bus charging at the charging station of  FIG. 2A ; 
         FIG. 3  is a schematic illustration of the charging station of  FIG. 2A ; and 
         FIG. 4  is a schematic illustration of another exemplary charging station. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure describes systems and methods for harnessing heat produced during the charging of an electric vehicle to do useful work and thereby increase efficiency and reduce costs. While principles of the current disclosure are described with reference to an electric bus, it should be understood that the disclosure is not limited thereto. Rather, the systems and methods of the present disclosure may be used in the charging of any vehicle (trains, cars, etc.) that uses one or more electric motors (alone or in combination with another power source) for propulsion. 
       FIG. 1  illustrates an electric vehicle in the form of an electric transit bus  10 . Electric bus  10  may include a body  12  enclosing a space for passengers. In some embodiments, some (or all) parts of body  12  may be fabricated using composite materials to reduce the weight of bus  10 . Without limitation, body  12  of bus  10  may have any size, shape, and configuration. In some embodiments, bus  10  may be a low-floor electric bus. As is known in the art, in a low-floor bus, there are no steps at the front and/or the back doors of the bus. In such a bus, the floor is positioned close to the road surface to ease entry and exit into the bus  10 . In some embodiments, the floor height of the low-floor bus may be about 12-16 inches from the road surface. In this disclosure, the term “about” is used to indicate a possible variation of ±10% in a stated numeric value. 
     Bus  10  may include a powertrain (not shown) that propels the bus  10  along a road surface. The powertrain may include an electric motor that generates power, and a transmission that transmits the power to drive wheels  24  of the bus  10 . Batteries  14  may store electrical energy to power the electric motor. In some embodiments, these batteries  14  may be positioned under the floor of the bus  10 , and may be configured as a plurality of battery packs. These battery packs may be positioned in cavities (not shown) located under the floor of the bus  10 , and may be accessible from below the bus  10 . The batteries  14  may have any chemistry and construction. In some embodiments, the batteries  14  may be lithium titanate batteries. In some embodiments, the layout and design of the batteries  14  may enable fast charging of the batteries  14 . By fast charging, batteries  14  may be recharged (to greater than about 95% state of charge) in less than or equal to about 10 minutes. 
     A charging interface  16  may be provided on the roof of the bus  10  (or elsewhere) to charge the batteries  14 . The charging interface  16  may include components that interface with a charge head assembly  32  of an external charging station to charge the batteries  14 . These components may include a charging blade  16   a  and an alignment scoop  16   b . The alignment scoop  16   b  may align and direct the overhanging charge head assembly  32  towards the charging blade  16   a  to electrically connect them and charge the batteries  14 . 
     Electric bus  10  may be a transit bus that operates along a fixed route in a geographic area (city, town, airport, campus, etc.). Bus  10  may continuously travel on the route picking up and dropping off passengers at several bus stops along the route. One or more charging stations may be located on the route to charge the buses  10 . Some of these charging stations may be located at bus stops. A bus  10  may be recharged while passengers embark and disembark at the bus stop. 
       FIG. 2A  illustrates a bus stop  50  having a charging station  30 . A charge console  34  of the charging station  30  may be coupled to an electric grid that is supplied with energy (electricity) by a utility company. Single phase or three-phase AC current from the electrical grid may be directed into the charge console  34 . The charge console  34  may be electrically coupled, and adapted to provide power, to the charge head assembly  32 . The charge console  34  may house electrical components (e.g., rectifier, power converter, switches, safety mechanisms, etc.) that are configured to convert power from the grid to a form that may be supplied to the bus  10  through the charge head assembly  32 . A bus  10  may pull up to the bus stop  50  and position itself proximate the charge head assembly  32 . Electrodes in the charge head assembly may then separably interface with the charging interface  16  of the bus  10  to electrically connect the bus  10  to the charging station  30 . Details of the charge head assembly  32  and the interfacing of the charge head assembly  32  with the charging interface  16  are described in commonly assigned patent applications US 2013/0193918 A1 and US 2014/0070767 A1, which are incorporated by reference in their entirety herein. 
       FIG. 2B  illustrates a bus  10  with its charging interface  16  electrically connected with the charge head assembly  32 . In the discussion that follows, reference will be made to both  FIGS. 2A and 2B . The charging interface  16  and the charge head assembly  32  may include mating electrodes that indicate (e.g., by a pilot signal) a proper electrical connection between the bus  10  and the charging station  30 . Upon receipt of this pilot signal, charging of the bus  10  may be initiated. During charging, single phase or three-phase AC current from the electric grid may be converted to DC current having variable power in the charge console  34  and input to the bus  10  through the charge head assembly  32 . This DC power may be used to charge the batteries  14 . The conversion of AC to DC current and the flow of current through electrical contacts of the charging station  30  and the bus  10  produces heat. 
       FIG. 3  is a schematic illustration of the charging of bus  10  at charging station  30 . At the charge console  34 , the AC current from the grid is converted to DC current at a rectifier  42 . The DC current is then controlled with a secondary power converter  44  to achieve the desired power. The charge console  34  may be configured to charge the bus  10  at any value of power (500 KW, 300 KW, etc.). As known in the art, the rectifier  42  and the power converter  44  include electrical devices such as insulated-gate bipolar transistors (IGBTs) and diodes that function to convert the AC current to DC current at the desired power. The conversion of AC current to DC current and the flow of this current to the batteries  14  produce heat. At 95% conversion efficiency, about 25 kW of heat is generated while performing a 500 KW charge. A majority of this heat is generated in the charge console  34 . A coolant may be circulated through the charge console  34  to collect the heat produced therein, and discharge the collected heat at selected areas of the bus stop  50 , located remote from the charge console  34 , for heating. 
     In general, any type of coolant may be used to collect heat from the charge console  34 . In the embodiment illustrated in  FIG. 3 , cool air  40 , directed into the charge console  34  through a vent  38 , is used to collect the heat from the heat producing components therein. The heated air  48  from the charge console  34  may be directed through a duct  43  and discharged at an area of the bus stop  50  that is desired to be heated. Duct  43  may be a conduit (pipe, air passage, etc.) that is fluidly coupled to an opening of the charge console  34  and extending to the area which is desired to be heated. The duct  43  may include one or more air moving components (e.g., fans, blowers  45 , etc.) that are configured to force the heated air through the duct  43 . Although not illustrated, duct  43  may also include air handling (filter racks or chambers, sound attenuators, dampers, etc.) and flow modifying components (louvers, etc.) to condition the air before it is discharged at the desired location. 
     The heated air  48  may be used to heat any desired area of the bus stop  50  that is remote from the charge console  34 . In prior art charging stations, air used to cool the console is exhausted to the atmosphere through a vent formed on the console (typically, on the top of the console). In contrast, in the current disclosure, the air used to cool the charge console  34  is exhausted to a location remote from the charge console  34  to heat this location. In this disclosure, the phrase “remote from” the charge console  34  is intended to exclude applications in which the heated air is exhausted immediately adjacent to the charge console  34  (as in prior art charging stations). That is, in this disclosure, a location remote from the charge console  34  refers to a location that is not immediately adjacent to the charge console  34 . While the distance of a remote location from the charge console  34  may vary with application, in some embodiments, this remote location may be &gt;5 feet from the charge console  34 . 
     The heated air  48  may be used to heat any desired area of the bus stop  50  that is remote from the charge console  34 . In some embodiments, the heated air  48  may be used to heat a passenger waiting area (e.g., waiting room, area in front of the bus doors, etc.) of bus stop  50 . In some embodiments, snow/ice in the passenger area may be melted using the heated air  48  from console  34 . In such embodiments, the duct  43  from the charge console  34  may terminate at the passenger waiting area to direct the heated air  48  to this area. In some embodiments, the heated air  48  may be used to heat the charging interface  16  of the charging bus  10 . Accumulated snow and ice on the roof of the bus  10  may make the electrical connection between the charging interface  16  and the charge head assembly  32  weak. Heated air  48  blown over the charging interface  16  may assist in melting the accumulated snow/ice and make a good electrical connection between the charging interface  16  and the charge head assembly  32 . In such embodiments, the duct  43  may extend from the charge console  34  to a region proximate the charge head assembly  32 . 
     In some embodiments, the duct  43  may direct the heated air  48  to the charge head assembly  32 , and the heated air  48  may flow over the charging interface  16  through the charge head assembly  32 . In such embodiments, the heated air  48  may heat the mating electrodes of the charge head assembly  32  and the charging interface  16 . In some such embodiments, the electrical conduit that directs power from the charging console  34  to the charge head assembly  32  may also extend through, or alongside, duct  43 . In some embodiments, the heated air  48  may be directed to other areas of the bus stop  50 , such as, for example, over the top of a charging bus, over a seating area of the bus stop (even to heat seats), at the front and/or rear door of the charging bus, at the curb near the charging bus, etc. It is also contemplated that the heated air  48  may be fluidly coupled to a nearby building heating system to heat the bus stop  50  or another portions of another building. 
     In some embodiments, duct  43  may extend from the charge console  34  to different areas of the bus stop  50 . For example, the duct  43  may include branches to direct the heated air  48  from the charge console  34  to some or all of the regions described above. In some embodiments, flow control devices (e.g., air vanes, guides, etc.) may selectively direct the heated air  48  through a desired branch of the duct  43 . Thermostats and/or switches may be used to select the branch of the duct  43  through which the heated air  48  flows. For example, thermostats positioned in different areas (charge head assembly  32 , curb, etc.) of the bus stop  50  may automatically operate air guides in the duct  43  and selectively direct the heated air  48  to a desired area. It is also contemplated that, in some embodiments, the air guides may be operated manually to selectively direct the heated air  48  to the desired area. 
     In some embodiments, a control system may control the flow of air through the ducts  42 . For example, based on predetermined selection criteria (number of passengers waiting in an area, ambient temperature of an area, etc.), the control system may select the areas to which heated air  48  is directed. Based on this selection, the control system may operate the air guides to direct the heated air  48  to the selected area. In some embodiments, the control system may control the flow rate of air through the charge console  34  to adjust the temperature of the heated air  48 . For example, the control system may reduce the flow rate of air flowing through the charge console  34  to increase a temperature of the heated air  48  and decrease the flow rate of air flowing through the charge console  34  to reduce the temperature of the heated air  48 . In some embodiments, the control system may mix the heated air  48  with other air to adjust its temperature. For example, a mixing chamber may be provided in duct  43 , and the control system may mix ambient air with the heated air  48  to reduce its temperature. In some embodiments, duct  43  may include heating elements (filament heaters, etc.) that may be activated to increase the temperature of the heated air  48 . 
     The duct  43  may extend above ground (as illustrated in  FIG. 3 ) and/or underground. In some embodiments, branches of the duct  43  that direct the heated air  48  to some areas (e.g., charge head assembly  32 , passenger waiting area, etc.) may extend above ground, while branches of the duct  43  that directs the heated air  48  to other areas (e.g., to the curb adjacent to the charging bus) may extend underground. In some embodiments, the heated air  48  may transfer heat to a liquid heat exchanger (not shown) to provide a warm water heating loop for selected areas. For example, in some embodiments, a duct  43  may exhaust heated air  48  to some areas of the bus stop for heating the area (e.g., passenger waiting area, etc.), and a warm water loop (e.g., embedded in the curb) may be used to heat the curb (or other areas). 
     In some embodiments, a liquid coolant may be used to remove heat from the charge console  34 .  FIG. 4  illustrates an exemplary embodiment of a charge console  34  with a liquid cooling loop  56  having a liquid coolant flowing therethrough. A cooler coolant (e.g., cool water  52 ) may absorb heat from the heat producing components of the change console  34  and exit as a warmer coolant (warm water  54 ). The warm water  54  may then be used to heat any desired area of the bus stop  50 . In some embodiments, the liquid cooling loop  56  may be fluidly coupled to a building heating system to assist in heating of the building. The liquid cooling loop  56  may be an open loop system or a closed loop system. 
     In some embodiments, the heated liquid coolant (in loop  56 ) from console  34  may be further heated using waste heat from other sources (e.g., building heating system, etc.) before being used to heat a desired area of bus stop  50 . In some embodiments, the liquid cooling loop  56  may be a closed loop. That is, after heating the desired area of the bus stop  50 , the cooled coolant may be recirculated back to the console  34  to absorb more heat. It is also contemplated that, in some embodiments, the liquid coolant loop  56  may be an open loop. For instance, after absorbing heat from the console  34  (and other sources), the heated coolant may be discharged in a desired area of the bus stop  50  (the floor of the passenger waiting area, curb by the bus, road surface proximate the charging station, etc.) to melt accumulated ice/snow. In some embodiments, the heated coolant may be discharged on the charging interface  16  of the bus to assist in melting accumulated ice/snow. 
     In some embodiments, a liquid coolant of the bus  10  may be used to cool the battery  14  and/or other heat producing components of bus  10 . This heated coolant in the bus  10  may be circulated proximate the charging interface  16  to heat and melt any accumulated ice/snow from the charging interface  16 . In some such embodiments, the heated liquid coolant from loop  56  may be used to heat the charge head assembly  32 . Heating the charging interface  16  using the heated liquid coolant from the bus  10 , and the charge head assembly  32  using the heated coolant from the console  34  may enable the formation of a good electrical connection between the bus and the charging station. 
     In some embodiments, the coolant from the console (e.g., loop  56 ) may pass into the bus  10  to combine with the coolant of the bus  10  and jointly cool the heat producing components in the bus  10 . For example, in some embodiments, conduits or pipes that transport the liquid coolant of console  34  may interface with, and make a leak-proof seal with, a conduit transporting the coolant of the bus  10  to fluidly couple the coolants together when the bus  10  is charging. In some embodiments, the charging interface  16  and the charge head assembly  32  may include separable leak-free fluid interconnections that enable transfer of the coolant from the console  34  to the bus  10  (and vice versa) with minimal leak. When the charge head assembly  32  interfaces with the charging interface  16  during charging, the coolant from loop  56  may pass into the bus  10  to combine with and cool the heat producing components of the bus  10 . Transferring the coolant through the charging interface  16  may help cool the motor, the inverter, and other heat producing components of the bus  10  and the bus stop  50  while also warming and melting ice/snow from the charging interface  16 . 
     While principles of the present disclosure are described with reference to harnessing the heat produced while charging an electric bus, it should be understood that the disclosure is not limited thereto. Rather, the systems and methods described herein may be employed while recharging any electric vehicle (all-electric or hybrid vehicles). Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, embodiments, and substitution of equivalents all fall within the scope of the embodiments described herein. Accordingly, the invention is not to be considered as limited by the foregoing description. For example, while certain features have been described in connection with various embodiments, it is to be understood that any feature described in conjunction with any embodiment disclosed herein may be used with any other embodiment disclosed herein.