Abstract:
An apparatus for providing transportation includes an electric vehicle having a battery, an electric motor, a transceiver, and a battery manager. The battery manager includes a controller configured to control flow of charge between said battery and the electric motor at least in part in response to information received by the transceiver.

Description:
FIELD OF DISCLOSURE 
     This disclosure relates to electric vehicles, and in particular, to battery management for electric vehicles. 
     BACKGROUND 
     Electric vehicles are generally more costly than comparable gasoline powered vehicles. This cost differential arises in great measure as a result of the batteries in electric vehicles. 
     Known battery management systems protect the valuable investment in a battery by preventing damage from overcharging or excess depletion. In doing so, they postpone the need to replace the battery. However, these known battery management systems do nothing to manage the overall cost of a battery in the first place. 
     SUMMARY 
     The invention is based in part on the recognition that a battery is in effect a consumable item in much the same way that gasoline is a consumable item in a conventional vehicle. Thus, to charge the consumer for the cost of a battery at the time of purchase is analogous to charging the consumer for the cost of gasoline to be used by the vehicle at the time of purchase. With this perspective in mind, it should come as no surprise that electric vehicles tend to be more costly. 
     The invention thus aims to provide a technical solution to the problem of allocating the bolus of cost associated with a battery purchase over time in a way that makes it economically practicable to sell electric vehicles at costs that make them competitive with conventional vehicles. 
     In one aspect, the invention features an apparatus for providing transportation. Such an apparatus includes electric vehicle having a battery, an electric motor, a transceiver, and a battery manager. The battery manager includes a controller configured to control flow of charge between the battery and the electric motor at least in part in response to information received by the transceiver. 
     Information received by the transceiver can be anything indicative of use of the battery, such as a charge ration or a time ration, or a ration of distance travelled. 
     In some embodiments, the controller is configured to receive, via the transceiver, information representative of a charge ration and to control operation of the battery based on a difference between the charge ration and accumulated charge drawn since receiving the information representative of the charge ration. 
     In other embodiments, the controller is configured to halt flow of charge between the battery and the electric motor at least in part in response to information received by the transceiver. 
     In yet other embodiments, the controller is configured to receive, via the transceiver, information representative of a charge ration and to halt flow of charge from the battery when the charge ration and an accumulated charge drawn since receiving the information representative of the ration are equal. 
     Also included among the various embodiments of the invention are those in which the controller is configured to receive, via the transceiver, information representative of a charge ration and to provide a warning when a difference between the charge ration and an accumulated charge drawn since receiving the information representative of the charge ration reaches a pre-selected value. 
     In some embodiments, the controller is configured to receive instructions, via the transceiver, to immediately exercise control over flow of charge between the battery and the motor. 
     Other embodiments of the invention further include a GPS unit in communication with the controller. Among these are those embodiments in which the controller is configured to exercise control over flow of charge between the battery and the motor based at least in part on information provided by the GPS unit, and those in which the GPS unit is configured to provide information representing a location of a repletion station for providing an opportunity to cause additional information to be provided to the controller via the transceiver. 
     In some embodiments, the apparatus also includes a clearinghouse for communicating with transceivers associated with a plurality of electric vehicles. Among these are embodiments in which the clearinghouse is configured to receive information from a plurality of repletion stations, the information being representative of a charge ration. 
     In yet other embodiments, the information received by the transceiver, includes information indicative of a maximum elapsed time. 
     Other embodiments include those in which the information received by the transceiver, includes information indicative of a maximum elapsed time and information indicative of a maximum allotted charge. Among these are those embodiments in which the controller is configured to track time usage and charge usage and to disable charge flow from the battery in response to detecting that the charge usage has reached a first pre-defined value and that the time usage has reached a second pre-defined value. Among this latter group of embodiments are those in which the controller is configured to track time usage and to begin to track charge usage when the time usage has reached a first pre-defined value. This third set of embodiments includes those in which the controller is configured to disable charge flow from the battery in response to detecting that the charge usage has reached a second pre-defined value. 
     Also included within the scope of the invention are apparatus that include any combination of the foregoing features. 
     In another aspect, the invention includes method for managing usage of a battery in an electric vehicle. Such a method includes receiving information indicative of a usage ration for the battery; during operation of the electric vehicle, causing the usage ration to traverse a trajectory through a battery usage space; detecting that the usage point has reached a designated point in the usage space; and disabling charge flow from the battery to a motor of the electric vehicle. 
     Some practices of the foregoing method also include causing the usage ration to traverse a trajectory includes traversing a path parallel to a time-usage axis followed by traversing a path parallel to a charge-usage axis. 
     In other practices of the method, receiving information indicative of a usage ration for the battery includes receiving, from a remote repletion site, information indicating that a user has paid of a usage ration. 
     Also included within the scope of the invention are methods that include any of the foregoing features. 
     In another aspect, the invention features an apparatus for providing transportation. Such an apparatus includes an electric motorcycle, the electric motorcycle having a battery, means for receiving information, and means for controlling flow of charge from the battery in response to information received by the means for receiving information. 
     In another aspect, the invention also includes a manufacture that includes a tangible and non-transitory computer-readable medium having encoded thereon instructions for causing the microcontroller to implement any of the foregoing features or for causing the microcontroller to execute any of the foregoing methods. 
     These and other features of the invention will be apparent from the following detailed description, and the accompanying figures, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an overview of a distributed battery management system; 
         FIG. 2  shows the components within one of the electric vehicles shown in  FIG. 1 ; and 
         FIG. 3  shows a process carried out by a microcontroller in one of the electric vehicles in  FIG. 1 ; 
         FIG. 4  shows trajectories of a usage parameter in a two-dimensional battery usage space for managing usage of the battery in  FIG. 2 ; 
         FIG. 5  shows a task carried out by a repletion site for providing additional rations for usage of the battery in  FIG. 2 ; 
         FIG. 6  shows a task carried out by the microcontroller to track usage of charge from the battery in  FIG. 2 ; and 
         FIG. 7  shows a task carried out by the microcontroller to implement a particular trajectory in the battery usage space of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     In one embodiment, shown in  FIG. 1 , a distributed battery management system  10  includes a central clearinghouse  12  in communication with repletion sites  14 A- 14 U and electric vehicles  16 A- 16 Z. Communication between the clearinghouse  12  and the repletion sites  14 A- 14 U can be a circuit-switched connection, such as that provided via a cellular phone network, such as a GSM network or by a wired telephone link. Alternatively, communication can be established by a packet-switched connection, such as via a computer network, for example the Internet. 
     Referring now to  FIG. 2 , each electric vehicle  16 A includes a battery  18  connected to an electric motor  20  by way of a gatekeeper  22 . Charge flows from the battery  18  to the electric motor  20  by way of a power transistor  24 , the gate terminal of which is controlled by a microcontroller  26  within the gatekeeper  22 . In normal operation, the microcontroller  26  maintains a voltage at the gate terminal that allows current to flow between the source and drain terminals of the transistor  24 . 
     The microcontroller  26  within the gatekeeper  22  receives data from a counter  28  that tracks a usage parameter indicative of an extent to which the battery  18  is used. In one embodiment, the counter  28  is a coulomb counter, and the usage parameter is how much charge flows from the battery  18 . In this embodiment, the microcontroller  26  maintains a running total of drawn charge in an accumulation register  30 . The microcontroller  26  periodically compares the drawn charge with a rationed charge stored in a rationed-charge register  32 . When the drawn charge exceeds the rationed charge, the microcontroller  26  sends a signal to the gate terminal to prevent further current flow between source and drain. This prevents the electric vehicle  16 A from moving under its own power. 
     In some embodiments, the microcontroller  26  determines when the drawn charge in the accumulation register  30  has almost reached the rationed charge in the rationed-charge register  32 , at which point it alerts the driver. This feature is particularly useful for preventing the driver from being surprised by a loss of power at an inconvenient location and prompts the driver to visit a suitable repletion site  14  to carry out a repletion as described below. 
     In order to operate the electric vehicle  16 A again, the driver must re-set the accumulation register  30  to zero. This requires the use of a transceiver  33  connected to the gatekeeper  22  via an antenna  34  for communication with the clearinghouse  12 . 
     The process of re-setting the accumulation register  30 , which is referred to as “repletion,” begins with the driver going to one of the repletion sites  14 A- 14 U in  FIG. 1 . The driver then provides information identifying his electric vehicle  16 A and tenders payment for authorization to withdraw additional charge from the battery  18 . The repletion site  14 U then transmits a message to the clearinghouse  12  indicating that the driver has made such a payment. In response, the clearinghouse  12  transmits a message to the gatekeeper  22 , which proceeds to re-set the accumulation register  30  and to re-set the maximum drawn charge to whatever the driver has paid for. This completes the repletion process. 
       FIG. 3  shows an example process implemented by the microcontroller  26  following the step of receiving a repletion credit from the clearinghouse  12  for a ration of charge (step  36 ). The microcontroller  26  sets the accumulation register to zero (step  38 ) and enables current flow from the battery  18  (step  40 ). The microcontroller  26  then waits a suitable interval (step  42 ) and determines the amount of charge drawn in that interval (step  44 ). Then, the microcontroller  26  adds this amount to the accumulation register  30  (step  46 ). If the amount shown in the accumulation register  30  comes too close to the rationed charge amount (step  48 ) in the charge ration register  32 , the microcontroller  26  sends a warning to the driver to find a repletion site  14 A- 14 U (step  50 ). If the amount in the accumulation register reaches the rationed amount (step  52 ), the microcontroller  26  shuts down the electric vehicle  16 A (step  60 ). 
     It is important to note that the distributed battery management system  10  described herein effectively decouples the process of charging the battery  18  from the process of using it. The battery  18  may be completely full of charge at the time the microcontroller  26  renders the electric vehicle  16 A inoperable. 
     In effect, when the driver pays for repletion, he is paying for the right to use the battery  18 . This provides a backhanded way of paying for the battery  18  itself independently of the charge in the battery. Since the battery  18  is effectively paid for over time through payment for the release of charge, the cost of the battery  18  no longer needs to be such a significant part of the cost of the electric vehicle  16 A. This in turn allows the electric vehicle  16 A to be sold at a price comparable to a conventional vehicle. 
     In another embodiment, the usage parameter is elapsed operating time. In this embodiment, the counter  28  is a time counter. The operation of such an embodiment is analogous to that described above in connection with  FIG. 3 . 
     In yet another embodiment, the usage parameter is a vector quantity rather than a scalar quantity. For example, the usage parameter can be a two-dimensional vector in which one element represents charge and the other represents elapsed time, as shown in  FIG. 4 . The act of repletion, in this case, can be viewed as establishing an initial location  27  of the usage parameter in the usage space. The microcontroller  26 , using the output of the counter  28 , determines a trajectory  29  of the usage parameter as it makes its way towards a designated end-point  31 , at which point further usage of the vehicle  16 A is forbidden. Some embodiments include a warning zone  37  surrounding the end-point  31  so that when a trajectory  29 ,  35  enters the warning zone  37 , the microcontroller  26  issues a warning to the user of the electric vehicle  16 A. 
     In some embodiments, the trajectory of the usage parameter is at all times parallel to the axes of the usage space. For example, in one embodiment, the microcontroller  26  first fully depletes time and then begins depleting charge. This is equivalent to a trajectory that with a first segment  33  parallel to the time axis until no time is left, and a second segment  35  that runs parallel to the charge axis until no charge is left. Conversely, the microcontroller  26  can deplete charge first and then time, with a corresponding impact on the trajectory of the usage parameter. In other embodiments, the trajectory  29  can involve depleting both time and charge according to some pre-defined function. 
     The usage space shown in  FIG. 4  is a two-dimensional usage space. In the embodiments that rely only on depleting a scalar usage parameter, the usage space is one-dimensional. However, in principle nothing prevents the use of n indicia of usage to define an n-dimensional usage space. Examples of other indicia of usage that could be used, either alone or with others, are the distance travelled, either measured mechanically by an odometer or tracked via GPS data. 
       FIGS. 5-7  show the operation of an embodiment in which the usage parameter is a two-dimensional vector having a time ration and an energy ration. 
       FIG. 5  shows a task carried out at a repletion site  14 A. The usage parameter  62  in this example is a two-dimensional vector having both a time ration T r    64  and a charge ration Q r    66 . The clearinghouse  12  receives, from the repletion site  14 A, a ration update indicating that payment for a vector (T r , Q r ) has been received (step  68 ). The clearinghouse  12  then updates the usage parameter for the user by incrementing the current value of the usage parameter (T w , Q w ) by the additional ration (T r , Q r ) (step  70 ). 
       FIG. 6  shows a first task carried out by the microcontroller  26  during operation of the vehicle  16 A. The microcontroller  26  waits a first time interval ΔT 1  (step  72 ) after which it evaluates an amount of charge DQ used during that interval (step  74 ). The microcontroller  26  then increments an accumulator Q acc  by that amount of charge DQ (step  76 ). Thus, the accumulator Q acc  maintains a running total of charge that has been used since it was last reset. 
       FIG. 7  shows a second task carried out by the microcontroller  26  during operation of the vehicle  16 A. The task begins with enabling charge flow from the battery  18  to the motor  20  (step  78 ). The microcontroller  26  then waits for a second time interval ΔT 2  that is longer than the first time interval ΔT 1  (step  80 ). The microcontroller  26  then inspects the available time ration T w  (step  82 ). If there is any remaining time ration T w , the microcontroller  26  decrements it by the second time interval ΔT 2  (step  83 ) and then resets the accumulator Q acc  (step  86 ). This has the effect of ensuring that the time ration T w  is used before the charge ration Q w . 
     On the other hand, if the available time ration T w  is exhausted (step  82 ), the microcontroller  26  begins depleting the charge ration Q w  (step  84 ). If any charge ration Q w  remains (step  88 ), the microcontroller  26  checks to see if the remaining charge ration Q w  is low enough to warrant issuing a warning (step  90 ). If a warning is appropriate, the microcontroller  26  issues one (step  94 ). In either case, execution proceeds with resetting the accumulator Q w  (step  86 ). 
     If, on the other hand, no charge ration Q w  remains, the microcontroller  26  disables power flow from the battery  18  (step  92 ). 
     Viewed more broadly, the apparatus disclosed herein is a system for controlling battery operation in a remote electric vehicle  16 A in response to some triggering event. In the embodiment described above, the event is the occurrence of equality between a rationed charge and an accumulated charge. However, in alternative embodiments, the distributed battery management system  10  can operate as a theft deterrent. If an electric vehicle  16 A is stolen, the vehicle&#39;s owner may communicate with the clearinghouse  12  to provide information concerning the theft, at which point the clearinghouse  12  may issue a signal to cause the microcontroller  26  of the stolen electric vehicle  16 A to shut down the battery  18 . If an electric vehicle  16 A is involved in illegal activity, for example in a car chase, police may seek a warrant to communicate with the clearinghouse  12  and cause the electric vehicle  16 A to be abruptly shut down. A lessor or electric vehicles  16 A- 16 Z may program the microcontroller  26  to shut down operation at the end of the lease period. 
     An optional GPS unit  27  provides a host of other triggering events related to location. For example, a dealer offering electric vehicles  16 A- 16 Z for test drives may wish to provide a way to prevent electric vehicles  16 A- 16 Z from being driven too far away from the dealership. 
     Control in response to a triggering event need not involve complete shut-down but may also involve throttling. For example, one may limit the rate of charge flow, thus controlling the power output and hence the vehicle&#39;s maximum velocity. In such cases, the presence of data from a GPS unit, together with data representative of speed limits in various locations provides a way to enforce speed limits. 
     A more benign use of the GPS unit is to communicate with a database of repletion stations and to identify a repletion station that is nearby. This is useful for drivers who may find that their accumulated discharge is approaching their charge ration. 
     A variety of electric vehicles can be used with the system described herein. However, a particularly attractive choice of electric vehicle is a motorcycle. Motorcycles are relatively light weight and tend to be used for short trips at low speed. As such, the use of a battery in a motorcycle is eminently practical. Moreover, many motorcycles are use highly polluting two-stroke engines. Replacement of such engines with an electric motor would thus offer significant environmental advantages.