Abstract:
A method and a control system for charging a battery in a plug-in hybrid or all electric vehicle, thermally conditioning the battery, and/or thermally conditioning the passenger compartment of the plug-in hybrid or all-electric vehicle. Multiple variables may be used in order to determine the optimal timing of conducting the charging and thermal conditioning processes including time required to complete the processes, energy costs, and user set preferences.

Description:
TECHNICAL FIELD 
     The present disclosure relates to electric vehicles. Specifically, the disclosure relates to battery charging of electrified vehicles, thermal management of the battery, and thermal management of the vehicle cabin. 
     BACKGROUND 
     Charging systems for batteries in electric vehicles, in one known form, provide a constant charge level when the electric vehicle is connected to the charging system. The charging system begins to charge the battery and then ceases charging once the battery is fully charged. The battery charging rate changes depending on the level of charge currently stored in the battery. An empty battery charges at a faster rate than one that is fuller. These known charging systems, however, do not account for the current charge level remaining on the battery, the thermal state of the battery, or external factors such as when the electric vehicle may be used again. Applying constant charge can be both cost and energy inefficient and detrimental to the durability and longevity of the battery. 
     In addition, a battery operates more efficiently and effectively at a temperature of approximately 75° Fahrenheit. If the temperature of the battery, due to ambient temperature or other factors, is very cold, then the battery outputs less power. On the other hand, high battery temperature reduces the lifetime of the battery. Also, by charging immediately upon being plugged in, the battery is unable to take advantage of a less expensive electrical utility rate available, for instance, late at night or very early in the morning. 
     Currently, when a driver resumes use of a vehicle after an extended time, the vehicle passenger compartment, also known as the cabin, will have a temperature equalized with its surroundings. As a result, when resuming vehicle use, the passenger compartment will be undesirably hot or cold if the ambient temperature is likewise hot or cold. Accordingly, further improvement in the art is desirable. 
     BRIEF SUMMARY 
     In one form, the present disclosure provides a control system for operating the battery charging system, the battery thermal conditioning system, and/or the vehicle cabin conditioning system in a plug-in hybrid or electrical vehicle. By providing a feedback control process in accordance with the disclosed embodiments, the battery charging can be performed in such a manner to quickly and efficiently charge the battery while maximizing batter power and battery life-expectancy but minimizing cost. 
     The present disclosure also provides a control system, which implements a strategy for the charging of electric vehicles and provides an input system to input various variables that will affect the operations of a control unit that in turn controls one or more of the battery charging system, the battery thermal conditioning system, and/or the vehicle cabin conditioning system. 
     In another form, the present disclosure also provides a method of charging a battery including calculating an amount of time until a drive time that has been preset by the driver or another source, calculating an amount of time required to charge the battery, determining a time to start charging the battery based on the two calculated amounts, and beginning to charge the battery at that time. The method may also provide for thermal conditioning of the battery and/or thermal conditioning of the vehicle cabin. 
     In another form, the charging system may be utilized to thermally manage the battery in order to maximize battery life and power. 
     In yet another form, the charging system incorporates inputs from the vehicle user, the battery system, external factors, or all three to thermally manage and charge the battery. 
     In yet another form, the method allows the vehicle user to heat or cool the vehicle prior to entry into the vehicle. 
     In another form, the present disclosure provides for a cost efficient charging strategy of the battery system. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description, including disclosed embodiments and drawings, are merely exemplary in nature intended for purposes of illustration only and are not intended to limit the scope of the invention, its application or use. Thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a control system for charging a battery in accordance with a disclosed embodiment; 
         FIGS. 2A and 2B  are a flow chart of a charging method in accordance with a disclosed embodiment; and 
         FIGS. 3A and 3B  are a flow chart of a charging method in accordance with a second disclosed embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a control system  10  for charging a battery according to a disclosed embodiment. In one embodiment, the control system  10  could be incorporated into a stand-alone charging device or a charging device incorporated with the electrical system of a home or other charging location. In another embodiment, some or all components of the control system  10  are incorporated into the vehicle itself. The charging device could then be connected into a vehicle&#39;s on-board control and electrical systems, among other systems. The control system  10  could thereby provide commands to the vehicle&#39;s on-board systems and supply charge to the vehicle&#39;s battery. The control system  10  provides an input system  15  to allow a user to input preset conditions such as the desired time the user intends to use the vehicle next, referred to as the drive time (DT), and the desired cabin temperature to which the user wishes the vehicle to be at when resuming use. The input system  15  also allows for external factors to be input into the control system  10  such as, e.g., the times of reduced electrical utility rates, a weather or temperature forecast for some duration of time in the future, and present ambient temperature. These factors may be input by the user or may be input from a different external source such as a computer network or ambient sensors (not shown). The input system  15  may be a keyboard, a hard-wired input terminal, a computer application (for example a smartphone application or an internet-based utility), or other similar devices or applications. 
     The system  10  also includes a control unit  20 , a battery charging system  25 , a battery thermal conditioning system  30 , and a vehicle cabin conditioning system  35 . Based on the user and external inputs, the control unit  20  controls a battery charging system  25 , which provides charge to the batteries of the vehicle, the battery thermal conditioning system  30 , which manages the temperature of the battery, and the vehicle cabin conditioning system  35 , which manages the temperature of the vehicle cabin according to the various disclosed embodiments. The control unit  20  may be a processor and may contain memory for storing computer instructions for carrying out the various functions performed by the control unit  20 . In one embodiment, the control unit  20  also maintains an internal clock to enable the control unit  20  to calculate durations of time between a time a calculation is performed and times input by the input system  15  for various actions. This internal clock may be set by the input system, may be externally supplied (e.g. by a satellite), or may be maintained internally. 
     The battery charging system  25  is configured to provide charge to the vehicle battery and balance the charge among the cells of the battery. The battery charging system  25  also provides feedback to the control unit  20  to notify the control unit  20  of the status of the charging and/or balancing of the battery. 
     The battery thermal conditioning system  30  acts to increase or decrease the temperature of the battery as required to either maintain the battery within a preset tolerance of the optimal battery temperature, or to bring the battery within the tolerance if the battery temperature is beyond the temperature. The battery thermal conditioning system  30  will cool or heat the battery as necessary. In one embodiment, the battery thermal conditioning system  30  is configured to provide feedback to the control unit  20  to notify the control unit  20  of the thermal state of the battery. 
     The vehicle cabin conditioning system  35  acts to cool or heat the vehicle as desired to bring the cabin temperature to within a preset tolerance of the preset cabin temperature. In one embodiment, the vehicle cabin conditioning system  35  is the vehicle&#39;s environmental control system. The vehicle cabin conditioning system  35  may also provide feedback to the control unit  20  to notify the control unit  20  of the thermal state of the vehicle cabin if desired. It is contemplated to provide a charging system that can regulate the temperature of the battery and increase cost efficiency in charging, while also providing a comfortable passenger compartment temperature when a user resumes use of the vehicle. 
       FIGS. 2A and 2B  show a method  100  for charging a battery and managing the temperature of the battery and cabin for a plug-in hybrid or all-electric vehicle. The charging system  10  is configured to implement the method  100  whereby the effectiveness of the battery is optimized by monitoring and controlling the charge level of the battery, the thermal condition of the battery (i.e., the battery temperature), and the vehicle cabin temperature. The method  100  may be implemented in software, stored in a computer readable medium (which could be a random access memory (RAM) device, a non-volatile random access memory (NVRAM) device, or a read-only memory (ROM) device), and executed by the control unit  20 . 
     Beginning at step  105 , the vehicle&#39;s user parks the car and connects the vehicle to a charging system  10  according to a disclosed embodiment. At this time, the user may input into the input system  15 , shown in  FIG. 1 , several factors including, for example, the time at which the user anticipates using the vehicle again and the desired temperature of the vehicle&#39;s passenger compartment when resuming use. In a second embodiment, these factors may be pre-programmed into the system. 
     After the vehicle is parked and connected to the charging system, the system  10  calculates several factors based on the state and condition of the battery at step  110 . The system  10  may input a drive time (DT) by either the user or a drive time may be pre-programmed into the charging system  10 . The system  10  will determine the duration of time until the preset drive time (D dt ), the duration of time required to fully charge the battery (D c ), the duration of time required to thermally condition the battery to a desired temperature (D tc ), the duration of time required to balance the charge among the battery cells (D bb ), and the duration of time required to condition the vehicle passenger compartment to the desired pre-set temperature (D cp ). 
     Based on these factors, the system  10  will calculate the time to start charging (T sc ), time to start thermal conditioning of the battery (T tc ), and the time to start cabin preconditioning (T cp ) from the time the user has set to start driving. Depending on the chosen embodiment, any of the charging, battery thermal conditioning, battery balancing, or cabin preconditioning acts can be done concurrently or consecutively. That is to say, D c , D tc , D bb , and D cp  may overlap for some or all of their durations. If any of the events are performed concurrently, the system  10  will draw more power, resulting in increased power consumption. Performing events concurrently can be used to take advantage of reduced electrical utility rates, as will be discussed in further detail below. Performing events concurrently can also enable the vehicle to be ready for use sooner. 
     In another embodiment, DT may not be set. If DT has not been set or programmed, the system  10  will calculate Dtc, Dbb, and Dcp, but will be unable to calculate Tsc, Ttc, or Tcp. If the Drive Time is not set, then the system will be unable to calculate the time to start charging, because the system doesn&#39;t know when charging must be completed. In an embodiment, the system can be configured to begin charging immediately, assuming that the vehicle will need to be available for use as soon as possible. 
     Next, at step  115 , the system  10  determines if the user input a time at which the user anticipates using the vehicle again or if the DT has been pre-programmed. If the user has not input a time or a time has not been pre-programmed, the method  100  continues to step  120 . At step  120 , the system  10  begins to charge the battery immediately. While charging the battery, the system  10  monitors the thermal condition of the battery. If the battery temperature moves beyond a predetermined tolerance above or below a desired temperature, the charging system  10  reduces the charging power to thermally condition the battery to maintain the battery at or about the desired temperature. In one embodiment, the desired temperature is 75 degrees Fahrenheit. In another embodiment, the charging system  10  maintains the battery temperature at 75° F.+/−5° F. It should be appreciated that the disclosure is not limited to a specific battery temperature. 
     When the battery is fully charged, the system  10  stops charging the battery (step  125 ) and reports the charge complete time (step  130 ). The system  10  then determines whether the battery cells require balancing (step  135 ) by determining if the charge level of any given cell is outside of a tolerance, either higher or lower than the charge of the other cells. If balancing is required, the system  10  balances the battery cells (step  140 ) by equalizing the level of charge among the cells of the battery. 
     At step  145 , the system  10  next calculates a thermal wake up time for the vehicle of when the battery temperature goes beyond the temperature tolerance of the battery. When that time is reached (step  150 ), the system  10  wakes up and confirms if the battery temperature is at the desired temperature. If thermal conditioning is required, the system  10  conditions the battery (step  155 ) and then recalculates the time for thermal wake-up (step  145 ). If thermal conditioning is not required, the system  10  recalculates the time for thermal wake-up (step  145 ). This loop continues until the user resumes use of the vehicle. 
     If, the system  10  determines at step  115  that DT has been set, the system  10  will determine if a reduced electrical utility rate will be available at step  160 . This determination may be based upon several different sources. In one embodiment, the system  10  communicates directly with the utility provider to determine when a reduced electrical utility rate is available. In a second embodiment, the system  10  is programmed with a time range in which a reduced electrical utility rate is available. In another embodiment, the system  10  may be programmed with different tiers of reduced electrical utility rates, to take advantage of the lowest cost charging possible. 
     If a reduced electrical utility rate is available for some or all of the time overlapping with any of D c , D tc , D bb , and D cp , the method  100  continues at step  500 , described in further detail below and with respect to  FIGS. 3A and 3B . If a reduced electrical utility rate is not available, the method  100  continues at step  165 . 
     At step  165 , the system  10  determines if the D dt  is less than or equal to a first set percentage of D c . In one embodiment, this first set percentage is 20% of D c . If the system  10  determines that the D dt  is less than or equal to the first set percentage, the method  100  continues at step  170 . In a second embodiment, the system  10  determines if the D dt  is less than the first set percentage. At step  170 , the system  10  determines if the battery requires thermal conditioning. If thermal conditioning is required, the system  10  begins to thermally condition the battery at step  175 . In one embodiment, after thermal conditioning is complete, the system  10  begins charging the battery at step  180 . In another embodiment, the system  10  conditions and charges the battery at the same time. If battery conditioning is not required, the method  100  proceeds directly from step  170  to step  180  and charges the battery until the user resumes use of the vehicle. 
     If, at step  165 , the system  10  determines that the D dt  is greater than the first set percentage of D c , the method  100  proceeds to step  185 . At step  185 , the system  10  determines if the D dt  is less than or equal to a second set percentage of D c . In another embodiment, the system  10  determines if the D dt  is less than a second set percentage of D c . In one embodiment, the second set percentage is 35% of D c . If D dt  is less than or equal to the second set percentage of D c , the method  100  goes to step  195 . If the D dt  is not less than or equal to the second set percentage of D c  (i.e. the D dt  is greater than the second set percentage of D c ), the method  100  goes to step  190 . At step  190 , the system  10  enables a number cabin preconditioning events or continuous preconditioning. At step  195 , the system  10  enables a number of cabin preconditioning events less than the number of cabin preconditioning events at step  190 . For example, the system  10  could enable three cabin preconditioning events at step  190 , but at step  195 , the system  10  could enable one cabin preconditioning event. A cabin preconditioning event is an event for a set duration in which the vehicle either cools or heats the cabin temperature to reach the preset desired cabin temperature. Continuous cabin preconditioning means that the system conditions the cabin until the preset cabin temperature has been reached. 
     The method  100  then continues at step  200 , at which point the system  10  determines if thermal conditioning of the battery is required. If required, the system  10  begins thermally conditioning the battery at step  205 . Otherwise, the system  10  begins to charge the battery at step  210 . Once thermal conditioning of the battery is completed, the system  10  begins charging the battery at step  210 . 
     In one embodiment, at step  215 , the system  10  monitors the battery balance to determine the battery balance. At a time that is the duration of time required for battery balancing before the drive time, the system  10  determines if battery balance is required. If required, the system  10  begins to balance the battery cells. 
     Next, at step  220 , the system  10  determines if the time to start cabin preconditioning (T cp ) has been reached. This time will depend on the number of cabin preconditioning events enabled at step  190  or step  195 . The system  10  will calculate the amount of time required to precondition the cabin to the preset temperature based on the cabin ambient temperature. If the time has not been reached or if an insufficient number of preconditioning events have been enabled, the method  100  continues at step  225  to determine if the battery balance has been completed. If battery balance has not been completed, the method  100  returns to step  215 . If the battery balance has been complete, the method  100  proceeds to step  230 . 
     At step  230 , the system  10  determines the amount of time remaining until the vehicle wake up time. Vehicle wake up time will depend on the configuration of the charging system  10  including the number of cabin preconditioning events that have been enabled, the temperature of the cabin, the temperature of the battery, and the preset temperature of the cabin. 
     Next, after calculating the vehicle wake up time, the system  10  determines if the battery is within the preset temperature tolerance of the optimal battery temperature at step  235 . If the temperature is not within the temperature tolerance, the method  100  proceeds to step  240  at which point the battery is thermally conditioned until the battery is brought within the temperature tolerance. 
     The system  10  continues processing this loop until T cp  has been reached at step  220 . Once the time for cabin preconditioning has been reached, the method  100  proceeds to step  245 , at which point the system  10  ceases battery balancing, and then begins cabin preconditioning at step  250 . The system  10  preconditions the vehicle until the preset cabin temperature has been reached, the preset number preconditioning events have occurred, or the user begins use of the vehicle. 
     If it was determined at step  160  that a reduced electrical utility rate will be available for some or all of the charging, battery conditioning, battery balancing, or cabin preconditioning times, the method  100  proceeds to step  500  to perform the low cost charging shown in  FIGS. 3A and 3B . 
     At the start of method  500 , the system  10  first determines the start (T srr ) and ending (T err ) times of the reduced electrical utility rate at step  505 . The duration of time from T srr  until T err  is the reduced electrical utility rate window. In one embodiment, the reduced electrical utility rate window may be a tiered structure with a first electrical utility rate, which is less expensive than the standard electrical utility rate, and a second electrical utility rate, which is less expensive than both the standard electrical utility rate and the first electrical utility rate. If multiple tiers of reduced electrical utility rates are available, the system will calculate start and end times for each tier. 
     Next, once the system  10  has determined T srr  and T err , the system  10  determines if T srr  is after T sc  (at step  510 ). If the reduced rate window does not begin until after T sc , the method  500  goes to step  515 . At step  515 , the system  10  determines the combination and power input of charging and battery thermal conditioning will take the most efficient advantage of the reduced electrical utility rate. Then, at step  520 , the system  10  begins thermal conditioning of the battery and/or charging as determined at step  515 . The charging continues until, at step  525 , the charging is completed. 
     Once the charging is completed, the system  10  begins balancing the battery at step  530 . While balancing the battery cells, the system  10  determines at step  535  if T cp  has been reached. If T cp  has been reached, the system  10  ceases balancing the battery at step  540  and begins cabin preconditioning at step  545 . 
     If T cp  has not yet been reached, the system  10  determines at step  550  if the battery cell balancing is complete. If balancing is not yet complete, the method  500  returns to step  530 , where the system  10  continues to balance the battery. If balancing is complete, the method  500  proceeds to step  555 , where the system  10  calculates the wake-up time. 
     At step  560 , the system  10  determines if the battery is within the tolerance of an optimal battery temperature. If the battery is within the tolerance, the method  500  returns to step  535  so the system  10  can determine if T cp  has been reached. If, at step  560 , the battery temperature is beyond the optimal temperature tolerance, the system  10  activates the thermal conditioning system  30  at step  565  and begins to condition the battery at step  570 . This loop continues until the battery is within the tolerance of the optimal battery temperature. 
     Returning to step  510 , if the system  10  determines that the reduced rate window begins before T sc , the method  500  proceeds to step  575 . At step  575 , the system  10  determines if the reduced window duration (D rr ) is shorter than D c . If D rr  is less than D c , the method  500  proceeds to step  580 , where the system  10  starts charging immediately and continues until charging is completed at step  525 . The method  500  will then proceed to step  530  and the subsequent steps as described above. At some point during the charge, T err  will occur and the electrical utility rate will return to the normal rate. 
     If D rr  is determined to be longer than D c  at step  575 , the system  10 , at step  585 , determines the latest time at which the system can begin charging the battery and still complete the charging, conditioning, balancing, and cabin preconditioning before T err . In one embodiment, the latest time is the sum of D c , D tc , D bb , and D cp  before T err . In another embodiment, the latest time is the longest of D c , D tc , D bb , and D cp  before T err  and some or all of charging, battery thermal conditioning, battery balancing, and cabin preconditioning are conducted concurrently. 
     Next, at step  590 , the system  10  beings charging at the latest time at which the system can complete the charging, conditioning, balancing, and cabin preconditioning and still complete these tasks before T err . As discussed above, in one embodiment, the latest time is the sum of D c , D tc , D bb , and D cp  before T err . In another embodiment, the latest time is the longest of D c , D tc , D bb , and D cp  before T err  and some or all of charging, battery thermal conditioning, battery balancing, and cabin preconditioning are conducted concurrently. 
     Next, at step  595 , the system  10  completes the charging and determines if battery balancing is required. If battery balancing is required, the system  10  balances the battery at step  600 . If battery balancing is not required, the method  500  continues at step  605 . While balancing the battery at step  600 , or if it was determined that battery balancing was not required, the system  10  determines if T cp  has been reached at step  605 . If T cp  has been reached, the system  10  stops balancing the battery at step  610  and begins cabin preconditioning at step  615 . 
     If, at step  605 , T cp  has not been reached, the method  500  continues at step  620 , at which point the system  10  determines if battery balancing has completed. If balancing is not complete, the method  500  returns to step  595 . If battery balancing is complete, the system  10  recalculates DT, T tc , and T cp  at step  625 , and then compares the amount of time until T err  (D err ) to D cp  and D cp  at step  630 . In one embodiment, if D err  is equal to or less than D cp , the system  10  begins cabin preconditioning at step  615 . If D err  is greater than D cp , the system  10  wakes up and begins conditioning the battery at step  635 . After which the system  10  returns to step  625  (discussed above).