Abstract:
A vehicle climate control system includes a cooling system including a chiller, a coolant circuit, a refrigerant circuit, a pump, and a compressor. The coolant circuit bypasses the chiller. The refrigerant circuit incorporates the chiller. The pump is configured to move coolant through the coolant circuit. The compressor is configured to move refrigerant through the refrigerant circuit. The vehicle climate control system also includes a controller configured to, in response to a temperature of a battery exceeding a threshold while the pump is moving fluid through the coolant circuit, activate the chiller and the compressor.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to thermal management systems for electrified vehicles. 
       BACKGROUND 
       [0002]    Hybrid electric vehicles and electric vehicles use a motor to propel the vehicle. Power is supplied to the motor by a battery. The battery is configured to store an electrical charge that may also be used to power other vehicle components. Efficient use of the battery allows the vehicle to be propelled by the motor. This may be achieved by using a cooling arrangement. Propelling the vehicle using a motor, powered by the battery, reduces the necessity of the vehicle to operate using an internal combustion engine. Reducing operation of the internal combustion engine increases fuel economy of the vehicle. 
       SUMMARY 
       [0003]    A vehicle climate control system includes a cooling system including a chiller, a coolant circuit, a refrigerant circuit, a pump, and a compressor. The coolant circuit bypasses the chiller. The refrigerant circuit incorporates the chiller. The pump is configured to move coolant through the coolant circuit. The compressor is configured to move refrigerant through the refrigerant circuit. The vehicle climate control system also includes a controller configured to, in response to a temperature of a battery exceeding a threshold while the pump is moving fluid through the coolant circuit, activate the chiller and the compressor. 
         [0004]    A thermal management method includes, in response to a temperature of a battery exceeding a threshold while a pump moves coolant through a coolant circuit that bypasses a chiller, altering an activation state of valving such that the coolant circuit incorporates the chiller. The thermal management method also includes, in response to a temperature of a battery exceeding a threshold while a pump moves coolant through a coolant circuit that bypasses a chiller, activating the chiller while a compressor moves refrigerant through a refrigerant circuit that also incorporates the chiller. 
         [0005]    A vehicle includes a traction battery, a thermal management system, and a controller. The thermal management system includes a radiator, chiller, valve, and pump configured to move coolant through a coolant circuit selectively incorporating one of the radiator and chiller based on a position of the valve. The controller is configured to, in response to a temperature of the coolant traversing a threshold resulting in a battery temperature adjustment demand while the position of the valve is such that the coolant circuit incorporates the radiator and bypasses the chiller, re-position the valve such that the coolant circuit bypasses the radiator and incorporates the chiller. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a schematic view of an electric vehicle; 
           [0007]      FIG. 2  is a fluid circuit diagram depicting flow of coolant and refrigerant through a battery chiller and cabin evaporator; 
           [0008]      FIG. 3  is a fluid circuit diagram depicting operation of a first cooling mode for an electric vehicle battery; 
           [0009]      FIG. 4  is a fluid circuit diagram depicting operation of a second cooling mode for an electric vehicle battery; 
           [0010]      FIG. 5  is a fluid circuit diagram depicting operation of a third cooling mode for an electric vehicle battery; 
           [0011]      FIG. 6  is a fluid circuit diagram depicting operation of a fourth cooling mode for an electric vehicle battery; 
           [0012]      FIG. 7  is a fluid circuit diagram depicting operation of a fifth cooling mode for an electric vehicle battery; and 
           [0013]      FIG. 8  is a control logic flow diagram depicting operation of the cooling system. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
         [0015]      FIG. 1  depicts a schematic of a typical hybrid-electric vehicle  10 . Certain embodiments, however, may also be implemented within the context of plug-in hybrids and fully electric vehicles. The vehicle  10  includes one or more electric machines  12  mechanically connected to a hybrid transmission  14 . In at least one embodiment, a single electric machine  12  may be mechanically connected to the hybrid transmission  14 . The electric machine  12  may be capable of operating as a motor or a generator. In addition, the hybrid transmission  14  may be mechanically connected to an engine  16 . The hybrid transmission  14  may also be mechanically connected to a drive shaft  18  that is mechanically connected to the wheels  20 . The electric machine  12  can provide propulsion through the drive shaft  18  to the wheels  20  and deceleration capability when the engine  16  is turned on or off The electric machine  12  also acts as a generator and can provide fuel economy benefits by recovering energy through regenerative braking The electric machine  12  reduces pollutant emissions and increases fuel economy by reducing the work load of the engine  16 . 
         [0016]    A traction battery or battery pack  22  stores energy that can be used by the electric machine  12 . The traction battery  22  typically provides a high voltage direct current (DC) output from one or more battery cell arrays, sometimes referred to as battery cell stacks, within the traction battery  22 . The battery cell arrays may include one or more battery cells. 
         [0017]    Propulsion using the electric machine  12  requires power from the battery  22 . Supplying power to the electric machine  12  causes the battery  22  to generate thermal energy. Thermal energy, in the form of heat, may degrade the charge stored within the battery  22 . Charging the battery  22  may also generate thermal energy degrading the battery  22 . This reduces the length of time the vehicle  10  may be propelled using the electric machine  12 . Electrified vehicles high voltage batteries require active thermal management to ensure full battery useful life, permit a proper charge, and meet vehicle driving performance attributes. It is not only durability but also keeping the battery below a temperature threshold allows the vehicle to be driven without battery power limits. In other words, battery temperature can limit electric vehicle drive performance. Hybrid vehicles usually supplement this torque hold and run the engine to make up the difference. Therefore, it may be advantageous to cool the battery  22 . Cooling the battery may dissipate thermal energy from the battery  22  and increase efficiency of the power transfer from the battery  22  to the electric machine  12 . This would allow the electric machine to propel the vehicle  10  for a longer period of time and reduce a period of time the vehicle is propelled by the engine  16 . Likewise, it may be advantageous to heat the battery  22  when the battery  22  is too cold. 
         [0018]    The various components discussed may have one or more associated controllers to control and monitor the operation of the components. The controllers may communicate via serial bus (e.g., Controller Area Network (CAN)) or via dedicated electrical conduits. 
         [0019]      FIG. 2  depicts a fluid circuit diagram for a cooling system  24  used to cool the battery  22 . The cooling system  24  uses a refrigerant and a coolant in different thermal circuits to optimize battery  22  performance. A first thermal circuit  23  and second thermal circuit  25  may be used to control the temperature of the coolant. A third thermal circuit  27  and fourth thermal circuit  29  may be used to control the temperature of a refrigerant. The third thermal circuit  27  may also be used to optimize the temperature of both the coolant and the refrigerant. The coolant may be a conventional coolant mixture, such as water and ethylene glycol. The refrigerant may be a conventional refrigerant, such as R134a or 1234yf. The third  27  and fourth  29  circuits could run simultaneously when cabin and battery thermal management is required. 
         [0020]    The first thermal circuit  23  and the second thermal circuit  25  may include a coolant pump  34 , the battery  22 , a radiator  42 , a chiller  28 , and a diverter valve  44 . The pump  34  is used to circulate the coolant through the first thermal circuit  23  and the second thermal circuit  25 . The pump  34  pumps the coolant to the battery  22 . The coolant may pass a coolant temperature sensor  36  before interacting with the battery  22  to monitor the temperature of the coolant. A battery temperature sensor  38  may be used to monitor the temperature of the battery  22 . 
         [0021]    A controller  40 , or control module communicates with the coolant temperature sensor  36  and the battery temperature sensor  38  to optimally control the flow of the coolant through the first and second thermal circuits  23 ,  25  based on temperature demands of the battery  22 . In at least one other embodiment, the controller may communicate with a plurality of temperature sensors  38 . The coolant interacts with the battery  22  to absorb heat from the battery  22 . The warmed coolant from the battery  22  is pumped into the radiator  42  through the first thermal circuit  23 . The radiator  42  cools the warmed coolant using ambient air flowing across the radiator  42 . The radiator  42  allows the coolant to dissipate the thermal energy absorbed from the battery  22  and be cycled back to the battery  22  for further cooling. 
         [0022]    The diverter valve  44  may be used to regulate the flow of the coolant from the radiator  42 . If an ambient temperature is above a predefined threshold value or the battery temperature is above a predefined battery temperature threshold, then the radiator  42  may not provide sufficient cooling to the coolant to meet battery cooling demands. The diverter valve  44  may be actuated by the controller  40  to retard coolant flow from the radiator  42  when the ambient temperature is above the threshold. When actuated, the diverter valve  44  forces the coolant to be pumped by the pump  34  through the chiller  28  in the second thermal circuit  25 . For example, after absorbing thermal energy from the battery  22  the coolant may also be cycled through the chiller  28  to sufficiently cool the coolant to meet battery cooling demands. The same cooling circuit may be used to warm the battery  22  with or without a heater  45 . This cooling circuit may also be used to balance out the temperatures across the battery  22 . 
         [0023]    The third and fourth thermal circuits  27 ,  29  may include a compressor  46 , a condenser  48 , a chiller  28 , and an evaporator  50 . The compressor  46  pressurizes and circulates the refrigerant through the third and fourth fluid circuits  27 ,  29 . A pressure sensor  51  and temperature sensor  53  determine the pressure and temperature of the refrigerant necessary to measure a superheat value of the refrigerant. Another pressure sensor  52  may monitor a pressure of the refrigerant as it passes from the compressor  46  to the condenser  48  to determine a pressure ratio of the refrigerant based on the pressure from pressure sensor  51 . The compressor  46  circulates the refrigerant to the condenser  48 . The condenser  48  may include a fan  54 . The condenser  48  is configured to condense the refrigerant from a gas to a liquid to further cool the refrigerant. If the refrigerant pressure is above a predefined threshold, then the controller  40  may activate the fan  54 . The fan  54 , in conjunction with grille shutters (not shown), aids to further dissipate thermal energy from the refrigerant. 
         [0024]    The refrigerant may be circulated within the fourth thermal circuit  29  based on a demand from the evaporator  50 . The condenser  48  in conjunction with the fan  54  aids to dissipate heat absorbed by the refrigerant in the fourth thermal circuit  29  to meet the demand of the evaporator  50 . Before entering the evaporator  50 , the refrigerant flows through a first expansion valve  57 . The first expansion valve  57  may be an electronic expansion valve actively controlled by the controller  40 . An additional temperature sensor  59  is used with the expansion vale  57  to regulate the flow of refrigerant through the evaporator  50 . In at least one other embodiment, the first expansion valve  57  may be a passive thermal expansion valve. A refrigerant shut off valve  56  may be used to shut off refrigerant flow through the fourth thermal circuit  29 . The refrigerant shut off valve  56  may also be used to allow refrigerant flow through the evaporator  50 . When the refrigerant shut off valve allows refrigerant flow through the evaporator  50 , refrigerant flows through both the third  27  and the fourth  29  thermal circuits provided that electric expansion valve  58  is open. 
         [0025]    The third thermal circuit  27  may additionally include the chiller  28  and a second expansion valve  58 . The chiller  28  may also be configured to effectuate a heat transfer of the refrigerant. The refrigerant shut off valve  56  only blocks refrigerant flow to the evaporator  50 . To allow refrigerant flow through the chiller  28 , only expansion valve  58  needs to open. The second expansion valve  58  may be an electronic expansion valve actively controlled by the controller  40 . In at least one other embodiment, the second expansion valve  58  may be a passive thermal expansion valve. The second expansion valve  58  is configured to change the flow of the refrigerant based on the demand of the chiller  28 . The refrigerant, passing through the chiller  28 , transfers heat with the coolant to further aid to dissipate the thermal energy generated from operation of the battery  22 . 
         [0026]    The chiller  28  may also be in fluid connection with a heater  45 . The heater  45  is configured to warm the coolant. This allows the thermal management system  24  to provide heating as well as cooling to the battery  22 . The thermal management system  24  determines whether the battery  22  requires heating. If the battery  22  requires heating, the thermal management system  24  uses a plurality of heating levels to meet the demand from the battery  22 . Therefore, the thermal management system  24  may be a thermal management cooling system  24  or a thermal management heating system  24 . 
         [0027]    When the coolant is pumped through the chiller  28  because the diverter valve  44  has been actuated, the refrigerant may aid to absorb thermal energy from the coolant in the chiller  28 . This is consistent with an active cooling system. Active cooling via heat transfer from the coolant to the refrigerant allows further optimization of the battery temperature. Therefore, the third thermal circuit  27  incorporates the chiller  28  and the compressor  46  through the second expansion valve  58 . 
         [0028]    The controller  40  may implement control logic described below in order to optimize cooling within the chiller  28  and the evaporator  50 . While schematically illustrated as a single module in the illustrated embodiment, the controller  40  may be part of a larger control system and may be controlled by various other controllers throughout the vehicle, such as but not limited to, a vehicle system controller that includes a battery energy control module. 
         [0029]      FIG. 3  depicts a fluid circuit representative of a first cooling mode  60  for the thermal management system  24 . The first cooling mode  60  activates the pump  34  and the diverter valve  44 . The pump  34  pumps the coolant through the second thermal circuit  25  to the battery  22 . Energizing the diverter valve  44  forces the coolant to flow through the chiller  28 . The chiller  28  is not active in the first cooling mode  60 . The coolant is not actively being cooled when the chiller  28  is not active. In the first cooling mode  60  the battery temperatures are above a first threshold requiring minimal cooling. Therefore, the coolant does not need to be actively cooled by the chiller  28  in order to meet the cooling demands of the battery  22 . Energizing the diverter valve  44  and pumping coolant through the chiller  28  ensures the coolant does not overly cool the battery  22 . The goal of this cooling mode is to maintain homogeneous battery cell temperatures. 
         [0030]    The passive cooling of the radiator  42  may effectuate a heat transfer with the coolant in excess of the cooling demand of the battery  22 . The coolant temperature sensor  36  and the battery temperature  38  may indicate a battery temperature below an optimum threshold to the controller  40 . The controller  40  may then unnecessarily activate the heater  45 . This may require more energy to control the temperature of the battery  22 . Energizing the diverter valve  44  and directing the coolant through the inactive chiller  28  aids to further control the temperature of the coolant within the first cooling mode  60 . 
         [0031]      FIG. 4  depicts a fluid circuit representative of a second cooling mode  62  for the thermal management system  24 . The second cooling mode  62  is activated when the battery temperature sensor  38  indicates to the controller  40  that the battery temperature is above a second threshold. The second threshold is greater than the first threshold requiring more cooling than battery temperatures within the first threshold. The second cooling mode  62  is consistent with passive cooling through the first thermal circuit  23 . For example, the pump  34  pumps the coolant through the radiator  42 . The radiator  42  effectuates a heat transfer with the ambient air in order to meet the cooling demands the battery  22 . The passive cooling technique of the second cooling mode  62  may be dependent on the temperature of the battery  22 , the temperature of the coolant, and the ambient temperature through the radiator  42 . The second cooling mode  62  may be advantageous because it is a passive cooling mode. Passive cooling through the radiator  42  requires very little energy to cool the battery  22 . This aids to increase the efficiency of the battery  22  as well as to increase fuel efficiency of the vehicle  10 . However, if the coolant temperature sensor  36  and the battery temperature sensor  38  indicate that the temperature of the battery  22  or the temperature of the coolant are above a threshold such that the heat exchange between the coolant and the ambient temperature within the radiator  42  are not sufficient to meet the cooling demands of the battery, the controller  40  may activate another cooling mode. 
         [0032]      FIG. 5  depicts a fluid circuit representative of a third cooling mode  64  for the thermal management system  24 . The third cooling mode  64  is activated when the battery temperature sensor  38  or the coolant temperature sensor  36  indicates to the controller  40  that the battery temperature is above a third threshold. The third threshold is greater than the second threshold requiring more cooling to the battery  22 . The third cooling mode  64  uses an active thermal management cooling system  24  and pumps coolant through the first thermal circuit  23 . 
         [0033]    The diverter valve  44  is not active and the pump  34  pumps the coolant through the radiator  42 . However, the radiator  42  may not provide sufficient cooling to meet the cooling demand for the battery  22 . The increased cooling demand may be due to an increased ambient temperature, and increase coolant temperature, or increased battery temperature. The controller  40  activates fan  54 , which may also be attached with the radiator  42 . The fan  54  circulates air across the radiator  42 . The fan  54  effectuates heat transfer between the radiator  42  and the coolant to further reduce the temperature of the coolant. The fan  54  requires very little power to achieve the further cooling demands of the battery  22 . Using minimal power to meet the cooling demand from the battery  22  is again advantageous because it improves the efficiency of the battery  22  in the overall fuel economy of the vehicle  10 . 
         [0034]      FIG. 6  depicts a fluid circuit representative of a fourth cooling mode  68  of the thermal management system  24 . The fourth cooling mode  68  is activated when the battery temperature sensor  38  indicates to the controller  40  that the battery temperature is above a fourth threshold. The fourth threshold is greater than the third threshold again requiring more cooling to the battery  22 . The fourth cooling mode  68  prevents the battery  22  from being in a power-limited state. The fourth cooling mode  68  uses an active thermal management cooling system  24  to meet the increased cooling demands of the battery  22 . The active thermal management system  24  pumps coolant through the second thermal circuit  25  configuration discussed above wherein the coolant for the battery  22  may exchange thermal energy with the refrigerant within the chiller  28 . The refrigerant in this cooling mode  68  is flowing as described previously in the third thermal circuit  27  The fourth cooling mode  68  requires energy in order to meet the cooling demands of the battery  22  and provide efficient use of the battery  22 . Meeting the cooling demands of the battery  22  allows the thermal management system  24  to operate the vehicle using the battery  22  as the sole motive force for the vehicle. Extending the use of the battery  22  may decrease fuel consumption of the vehicle and provides better overall fuel efficiency of the vehicle. The thermal management system  24  still aids to increase the overall fuel economy of the vehicle through reducing the overall temperature of the battery  22 . 
         [0035]    The controller  40  energizes the diverter valve  44  which forces the coolant through the chiller  28 . The chiller  28  is active in order to meet the cooling demands of the battery  22 . However, within the fourth cooling mode  68  the battery temperature is such that the controller  40  prioritizes cooling to the evaporator  50 . If there is a demand for cooling to the evaporator  50 , the controller  40  may activate the shut off valve  56  directing the refrigerant to flow into the evaporator  50 . If the demand for cooling to the chiller  28  is present, the controller  40  may activate the expansion valve  58  to allow the refrigerant to flow through the chiller  28 . Forcing the refrigerant to flow through the chiller  28  transfers thermal energy from the coolant to the refrigerant within the chiller  28 . The transfer of thermal energy aids to further regulate the temperature of the coolant flowing from the chiller  28  and to the battery  22 . 
         [0036]      FIG. 7  depicts a fluid circuit representative of a fifth cooling mode  70  of the thermal management system  24 . The fifth cooling mode  70  is activated when the battery temperature sensor  38  indicates to the controller  40  that the battery temperature is above a fifth threshold or when only the battery needs cooling. The fifth threshold is greater than the fourth threshold requiring a large amount of cooling. The fifth cooling mode  70  is consistent with an active thermal management system  24 . The fifth cooling mode  70  uses the third thermal circuit  27  to achieve cooling to the battery  22 . The battery  22  may be in a critical or limited use state when the battery temperatures are high enough to activate the fifth cooling mode  70 . 
         [0037]    The thermal management system  24  biases cooling to the battery  22  when the battery  22  is in a critical condition. Biasing cooling to the battery  22  prevents degradation of the battery  22 . Preventing degradation of the battery  22  aids to ensure optimal use of the battery  22 . For example, the excessive thermal energy from the power discharge of the battery  22  may damage the battery structure in the critical use state, or fifth cooling mode. This may prevent the battery  22  from operating appropriately efficiently during future use. When the battery is in the limited use state, the thermal management system  24  turns off refrigerant flow through the cabin evaporator, despite the presence of a cabin cooling request. 
         [0038]      FIG. 8  depicts a control logic flow diagram for the thermal management system  24 . The control steps are implemented by the controller  40  to determine the appropriate cooling mode configuration for the battery. At  72 , the controller  40  determines if the battery needs thermal management. For example, signals from the battery temperature sensor may indicate a rise in the temperature of the battery. If at  72 , a change in battery temperature indicates to the controller  40  that the battery requires thermal management, at  74  the controller  40  determines whether the battery requires heating or cooling. At  74 , the controller  40  may determine battery heating is required and moves to heating mode determination at  76 . Using the temperature data from the battery temperature sensor, the controller  40  calculates the appropriate heating level at  78 . 
         [0039]    In order to determine the appropriate heating mode at  78 , the controller  40  compares battery temperature thresholds and the battery temperature sensor. For example, if at  78 , the battery temperature falls between two predefined temperature thresholds; the controller  40  operates at the first heating level at  80  to heat the battery. If at  78 , the battery temperature does not fall between the two predefined temperature thresholds, the controller  40  operates at the second heating level at  82  to heat the battery. 
         [0040]    At  74 , the controller may determine battery cooling is required. The controller  40  uses the temperature data from the battery temperature sensor to calculate the appropriate cooling mode to ensure efficient use of the battery. For example, at  84  the controller  40  determines what type of cooling mode needs to be activated. If at  84  the controller  40  determines that the battery cooling required is greater than an initial cooling mode, the controller  40  may request a different cooling mode when the battery temperature is greater than the first threshold for the first cooling mode. 
         [0041]    If at  84  the battery temperature data indicates that the battery temperature is not greater than the cooling achieved using the first cooling mode, the controller  40  indicates that the first cooling mode is needed. The decision at  84  to determine the cooling mode is primarily a function of battery coolant temperature, battery cooling modes, and ambient air temperature. At  90 , the controller  40  determines if the decision from  84  is the first cooling mode. If at  90 , the first cooling mode is the appropriate cooling mode; at  92  the controller  40  actuates actuators necessary to enable the first cooling mode, as described above. If at  84  the battery temperature data indicates that the battery temperature is greater than the cooling achieved using the first cooling mode, the controller  40  determines at  84  if the second cooling mode at  94  will achieve the battery cooling demand. If at  94  the second cooling mode provides enough cooling to meet the demand the battery, the controller  40  may activate the actuators necessary to achieve the second cooling mode at  95 . If at  84  the temperature of the battery indicated by the battery temperature sensor is greater than the cooling achieved using the second cooling mode, the controller may determine at  84  the third cooling mode at  96  is the appropriate mode to meet the demand of the battery  22 . 
         [0042]    At  84 , the controller  40  may use the temperature data of the battery from the battery temperature sensor to determine if activation of the third cooling mode will sufficiently cool the battery. If the cooling demand of the battery is not greater than the cooling achieved using the third cooling mode configuration, at  96  the controller  40  may activate the actuators necessary for the third cooling mode at  98 . If the cooling demand of the battery is greater than the cooling achieved using the third cooling mode, the controller at  84  may determine if the fourth cooling mode at  100  is sufficient to meet the demand from the battery  22 . 
         [0043]    At  84 , the controller  40  analyzes whether the cooling provided by the fourth cooling mode will be sufficient to meet the cooling demand of the battery  22 . If the cooling demand of the battery is less than the cooling provided through the fourth cooling mode, at  100  the controller  40  will activate the actuators necessary to enable the fourth cooling mode at  102 . If at  84 , the controller  40  calculates that the cooling provided to the fourth cooling mode is less than the cooling demand of the battery  22 , the controller  40  may determine at  84  that the fifth cooling mode may be sufficient to achieve the cooling demand of the battery. The controller  40  may evaluate, at  84 , the battery thermal conditions as being at a critically high temperature requiring limited use. Therefore, at  104  the controller  40  may activate the actuators necessary to enable the fifth cooling mode at  106  to bias cooling to the battery. 
         [0044]      FIG. 8  also depicts the basic control logic for the thermal management system  24 . The controller  40  evaluates if a certain cooling mode will achieve the cooling demand of the battery  22 . The cooling provided by the cooling modes may depend on external factors, such as the ambient temperature, whether the vehicle is moving, and the demand for cooling to the cabin. For example, if the ambient temperature is very low, then the controller  40  may only command that the first cooling mode is sufficient to meet the total cooling demand of the battery. Likewise, if the ambient temperature is very hot, the controller may only command the fifth cooling mode. The thermal management system  24  considers other factors besides battery temperature, such as the ambient temperature to allow the thermal management system  24  to account for various driving conditions. 
         [0045]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.