System and method for optimizing charging of an electric / hybrid vehicle via a utility grid

Abstract

A vehicle charging system (106) employed in a vehicle (100) configured to be charged from an external power source, the vehicle charging system (106) comprising: a battery assembly (108); a timer (112) comprising a processor; and a transceiver; wherein the timer (112) is coupled to the battery assembly (108) and is configured to electrically couple the external energy source to the battery assembly (108) to start charging the battery assembly (108) at a predetermined charging initialization time; wherein the transceiver is coupled to the processor and the processor is configured to determine the charging initialization time based on data from an external source wirelessly received by the transceiver; wherein a charging termination time is further determined based on data from the external source, and wherein during charging of the vehicle, upon reaching the charging termination time, it is determined whether the charging level of the battery assembly (108) is less than or equal to a minimum charging threshold, and if so, the charging is not terminated.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to electric / hybrid vehicles and, more particularly, to a method and apparatus for optimizing the charging timing of an electric / hybrid vehicle. BACKGROUND OF THE INVENTION

[0002] In a battery electric vehicle (BEV), an electric motor / generator is powered by a group of batteries configured as a battery pack or battery assembly that can be recharged from an external electrical source (e.g., the national grid). The BEV's electric motor / generator has certain advantages over the widely used internal combustion engine used in conventional vehicles. For example, an electric motor achieves significantly higher conversion efficiency and can produce torque without vehicle movement, eliminating the need for transmissions and torque converters. Additionally, an electric motor has the ability to recover kinetic energy through regenerative braking. Furthermore, an electric motor significantly reduces emissions during operation.However, despite the advantages associated with electric motors, BEVs have not been widely adopted mainly due to their limitations in terms of cost and performance (e.g., range).

[0003] Hybrid vehicles such as BEVs employ battery-powered electric motors; however, hybrid vehicles do so in combination with highly efficient heat engines, such as conventional internal combustion engines. By selectively using the electric motor (e.g., when the vehicle is stationary), the hybrid vehicle minimizes its reliance on the internal combustion engine, thereby saving fuel, minimizing emissions, and reducing running costs. Most recently, plug-in hybrid electric vehicles (PHEVs) have been developed, which employ high-capacity rechargeable battery arrays that allow the electric motor to operate for extended periods, thereby reducing reliance on the internal combustion engine. A PHEV may rely solely on the electric motor for short distances, avoiding the use of the internal combustion engine entirely.

[0004] BEVs and PHEVs are generally equipped with a connector cable that is electrically coupled to the battery assembly and that can be manually connected to an external energy source (e.g., the utility grid) to enable recharging of the battery assembly. For example, the connector cable may include a pin-type end that can be plugged into a household electrical outlet. The charging time can range from minutes to several hours, depending on the extent to which the battery assembly has been drained and the voltage / frequency of the electrical outlet. The time of day (TOD) during which the BEV / PHEV is charged is important for two main reasons: (1) in the aggregate, the charging TOD affects utility grid load levels; and (2) the charging TOD often determines the cost per kilowatt-hour that a consumer pays for electricity.

[0005] Thus, it should be appreciated that it would be desirable to provide a vehicle charging system that can (1) determine an optimal time period during which the battery assembly of an electric / hybrid vehicle should be charged, and (2) effect charging during the determined time period. Other desirable features and characteristics of the present invention will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

[0006] US 5,650,710 A discloses a device for controlling the start and stop of charging a battery of an electric vehicle, taking into account a calculated charging duration and a planned departure time. Further prior art is known from DE 297 07 965 U1, JP H10-262 305 A, US 2006 / 0 052 918 A1, and US 5,892,346 A. SUMMARY OF THE INVENTION

[0007] The object of the invention is to provide an improved system and method for optimizing charging of an electric / hybrid vehicle via a supply network.

[0008] To achieve this object, systems having the features of claims 1 and 6 and a method having the features of claim 11 are provided. Advantageous embodiments of the invention can be found in the subclaims, the description, and the drawings. DESCRIPTION OF THE DRAWINGS

[0009] The present invention is described hereinafter in conjunction with the following drawings, in which like reference numerals designate like elements, and: Fig. Figure 1 is an isometric view of a hybrid vehicle including a connector cable plugged into an external power outlet; Fig. 2 is a functional block diagram of a vehicle charging system according to an exemplary embodiment of the invention, which is used in Fig. 1 shown vehicle; Fig. 3 is a flowchart showing an exemplary charging initialization process performed by the Fig. 2 shown vehicle charging system can be implemented; Fig. 4 is a flowchart showing an exemplary charging termination process performed by the Fig. 2 shown vehicle charging system can be implemented; and Fig. 5 is a functional view of a fleet charging management system configured to coordinate the charging of multiple vehicles, each having a vehicle charging system deployed thereon. DESCRIPTION OF AN EXEMPLARY EMBODIMENT

[0010] The following detailed description is merely exemplary in nature and is not intended to limit the invention or its application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

[0011] Fig. 1 is an isometric view of a vehicle 100, such as a plug-in battery-powered electric vehicle or hybrid electric vehicle. The vehicle 100 is powered at least in part by an onboard battery assembly that can be recharged by connecting a connector cable 102 to an external power source. For example, the connector cable 102 may include a pin-type end configured to plug into a conventional electrical outlet 104 coupled to the national power grid (e.g., one of the three main power grid connections spanning the 48 contiguous states). According to the present invention, the vehicle 100 is equipped with a vehicle charging system that can determine an optimal charge initiation time (CIT) and initiate charging of the vehicle 100 according to the determined CIT.

[0012] Fig. 2 is a functional view of an exemplary vehicle charging system 106 deployed on vehicle 100. Vehicle charging system 106 includes a hybrid battery assembly 108 comprising a plurality of batteries, at least one of which has a rechargeable chemistry (e.g., nickel metal hydride, lithium ion, etc.). A power electronics unit 110, including a timer 112 (e.g., a processor), is coupled between battery assembly 108 and connector cable 102. Power electronics unit 110 may also include a voltage detector 113 for determining when connector cable 102 is connected to an external electrical source, such as electrical source 104. As described in more detail below, power electronics unit 110 may control charging of battery assembly 108 by selectively coupling external electrical source 104 to battery assembly 108 via connector cable 102.An energy storage control module (ESCM) 114 is also coupled to the battery assembly 108 and the power electronics unit 110. The ESCM 114 monitors various operating parameters of the battery assembly 108 (e.g., voltage, current, temperature, and / or charge levels).

[0013] The vehicle charging system 106 may also include additional components, such as an engine control module / transmission control module (ECM / TCM) 116, a conventional 12-volt battery 118, a user interface 120, and various other vehicle systems 122 typically employed on a motor vehicle (e.g., ABS, HVAC, etc.). According to the invention, the vehicle charging system 106 is provided with a transceiver to enable wireless communication via a communications network (e.g., a cellular phone network, a satellite network, etc.). For example, the vehicle charging system 106 may include a telematics module 124 (e.g., Onstar) with an antenna 126. The telematics module 124 may also track the position of the vehicle 100 using global positioning system technology. A plurality of interconnect devices 128 (e.g., serial data buses) electrically couple the components of the vehicle charging system 106.Overall, the connecting devices 128 may comprise a controller area network that uses standard communication protocols (e.g., J1850 type protocols).

[0014] The user interface 120 may include a user input (e.g., controls associated with a driver information center, an audio system, the vehicle route entry button or wand, etc.) configured to receive user selection data to enable customization of the charging process. For example, the user interface 120 may allow a user to select between different charging modes; e.g., a STANDARD CHARGING MODE, in which charging starts regardless of the time of day, and a CONSERVATION CHARGING MODE, in which charging starts at the predetermined charge initialization time (CIT). The interface 120 may also include a feedback generator (e.g., a sound generator or a display, such as a head-up display or a center console display) configured to indicate user selections (e.g., the selected mode).

[0015] Fig. 3 is a flowchart illustrating an exemplary charge initiation process that may be performed by the vehicle charging system 106. To begin, the power electronics unit 110 determines whether the connector cable 102 has been connected to the external electrical source 104, as indicated, for example, by a detector (e.g., the voltage detector 113) coupled to the cable 102 (STEP 130). If the connector cable 102 is determined to be coupled to the electrical source 104, the power electronics unit 110 queries the ESCM 114 to determine whether the battery assembly 108 is fully charged (STEP 132). If the battery assembly 108 is not fully charged, the power electronics unit 110 determines whether a user has selected the ECONOMY CHARGING MODE as described above (STEP 134).If the ECONOMY CHARGING MODE has not been selected, the power electronics unit 110 begins charging the battery assembly 108 (STEP 136). Charging continues until the connector cable 102 is disconnected (STEP 130) or the battery assembly 108 is fully charged (STEP 132).

[0016] If the unit 110 instead determines that the ECONOMY CHARGING MODE has been selected (STEP 134), the power electronics unit 110 sets the appropriate CIT (STEP 138) using any of a number of techniques. For example, the power electronics unit 110 may simply retrieve the CIT from on-board memory. In this case, the CIT may be a preprogrammed time stored in on-board memory, typically signifying the beginning of a period of low demand on the power grid (e.g., 10 p.m.). Alternatively, the CIT may have been preselected by a user (e.g., a driver) using the user interface 120. After setting the CIT, the power electronics unit 110 compares the CIT to the current time of day. If the current time is before the CIT, the power electronics unit 110 returns to STEP 130.However, when the current time has reached the CIT, the power electronics unit 110 starts charging the battery assembly 108 (step 136). Charging of the battery assembly 108 continues until the connector cable 102 is disconnected (step 130) or the battery assembly 108 is fully charged (step 132).

[0017] Rather than retrieving a pre-programmed or user-selected CIT from on-board memory, the power electronics unit 110 may instead be configured to determine a CIT by referring to data from an external source transmitted to the unit 110 by the telematics module 124. The data from the external source may indicate various parameters of the vehicle 100 and / or load levels of the local power grid. For example, the data from the external source may provide information indicating the current location of the vehicle 100. The power electronics unit 110 may use the current location of the vehicle 100 to determine a corresponding CIT, for example, by referring to a two-dimensional lookup table that associates multiple geographic locations with multiple location-specific CITs.Alternatively, the power electronics unit 110 may use the current location of the vehicle 100 to identify the time zone in which the vehicle 100 is located. After identifying the correct time zone, the power electronics unit 110 may simply initiate charging at a preprogrammed or user-selected time, as described above in connection with STEP 138 and STEP 140 (. Fig. 3). In this way, the vehicle charging system 106 can be configured to automatically compensate for time changes due to travel through multiple time zones and / or due to daylight saving time changes.

[0018] The vehicle charging system 100 may be configured to terminate charging according to user preferences. Fig. 4 is a flowchart illustrating exemplary charging termination processes that may be performed by the vehicle charging system 100. If desired, the Fig. 4 can be executed in conjunction with a charging initiation process which is similar to the charging process performed in conjunction with Fig. 3 described above. The power electronics unit 110 first determines, for example, by querying the ESCM 114 in the manner previously described (STEP 142), whether the battery assembly 108 is fully charged. If the battery assembly 108 is fully charged, charging is aborted (STEP 144). If, instead, the battery assembly 108 is not fully charged, the power electronics unit 110 determines a preferred charge completion time, or PCTT (STEP 146). Similar to the charge initialization time, the PCTT may be preprogrammed or previously selected by a user using the user interface 120. According to the invention, it is determined in relation to data from the external source. After setting the PCTT, the power electronics unit 110 compares the PCTT to the current time.If the power electronics unit 110 determines that the current time is before the PCTT (STEP 148), charging continues (STEP 150). If it is determined that the current time has reached the PCTT (STEP 148), the power electronics unit 110 determines a minimum charging threshold (STEP 152) (e.g., via a user selection process performed with the user interface 120). If the charge level of the battery assembly 108 is less than or equal to the minimum charging threshold (STEP 154), charging continues (STEP 150). In contrast, if it is determined that the charge level of the battery assembly 108 is greater than the minimum charging threshold (STEP 154), the power electronics unit 110 terminates the charging process (STEP 144).

[0019] In contrast to retrieving a stored CIT from on-board memory or setting a CIT from data from the external source as described above, the power electronics unit 110 may be configured to receive an associated CIT from the central controller, which may be used, for example, in a fleet charging management system. Fig. 5 is a functional view of an exemplary fleet charging management system 156 configured to coordinate the charging of multiple vehicles (e.g., vehicles 158, 160, and 162), each having a vehicle charging system deployed thereon (e.g., the vehicle charging system shown in Fig. 2). The fleet charging management system 156 includes a central controller 164 coupled to a utility grid monitoring device 168 (e.g., an area operator, utility substation, GPS satellite, etc.) configured to monitor the voltage and current levels at critical connection points of the utility grid. The controller 164 is also coupled to a wireless transceiver 166, which may include, for example, a satellite dish. The satellite dish 166 cooperates with the satellite 170 to enable bidirectional communication between the controller 164 and the vehicles 158, 160, and 162.

[0020] The fleet charging management system 156 may coordinate the charging of vehicles 158, 160, and 162 to help balance peak load levels of the power grid. In particular, the controller 164 may assign an optimal charge initialization time (CIT) to each vehicle in the following manner. Initially, the controller 164 may take an inventory of the number of vehicles waiting to recharge, for example, by querying each vehicle's vehicle charging system. Alternatively, each of the vehicle charging systems may be configured to send a signal indicating a pending charging cycle at a particular time in the pre-charging process. Referring briefly to Fig. 2 and Fig.3, this can be achieved by configuring the power electronics unit 110 to transmit a signal via the telematics module 124 upon determining that the CONSERVATION MODE has been selected (STEP 134). After inventorying the vehicles waiting to recharge, the controller 164 next determines a time period during which the regional power grid experiences a relatively low load. The controller 164 then determines and assigns vehicle-specific CITs to evenly distribute vehicle charging over this time period. For example, if it is determined that the power grid experienced a relatively low load between 10 p.m. and 4 a.m., the controller 164 may assign a charge initiation time of 10 p.m. to vehicle 158, a charge initiation time of midnight to vehicle 160, and a charge initiation time of 2 a.m. to vehicle 162.

[0021] The vehicle charging systems deployed on vehicles 158, 160, and 162 may also be configured to transmit additional data indicating an estimated charging time duration. For example, the vehicle charging systems may send the controller 164 the current charge level of the battery assembly and / or the duration of past charging cycles. As will be appreciated by one of ordinary skill in the art, the controller 164 may use such information to more accurately determine an optimal charging time distribution.

[0022] Thus, it should be appreciated that a vehicle charging system has been provided that can (1) determine an optimal time period during which the battery assembly of a hybrid / electric vehicle should be charged, and (2) effect charging during the determined time period. Although the vehicle charging system of the present invention has been generally described above in connection with a plug-in electric hybrid vehicle, it should be understood that it can be used on a battery-powered electric vehicle or on any other vehicle that includes at least one onboard battery that can be recharged from an external power source.

[0023] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that a wide variety of variations exist. It should also be noted that the exemplary embodiment or exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description provides those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes in the function and arrangement of elements may be made without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.

Claims

[1] A vehicle charging system (106) employed in a vehicle (100) configured to be charged from an external power source, the vehicle charging system (106) comprising: a battery assembly (108); a timer (112) comprising a processor; and a transceiver; wherein the timer (112) is coupled to the battery assembly (108) and is configured to electrically couple the external energy source to the battery assembly (108) to start charging the battery assembly (108) at a predetermined charging initialization time; wherein the transceiver is coupled to the processor and the processor is configured to determine the charging initialization time based on data from an external source wirelessly received by the transceiver; wherein a charging termination time is further determined based on data from the external source, and wherein during charging of the vehicle, upon reaching the charging termination time, it is determined whether the charging level of the battery assembly (108) is less than or equal to a minimum charging threshold, and if so, the charging is not terminated. [2] The vehicle charging system (106) of claim 1, further comprising a memory coupled to the processor, the memory configured to store the charging initialization time. [3] The vehicle charging system (106) of claim 2, further comprising a user interface (120) coupled to the processor, the user interface (120) configured to enable adjustment of the charging initialization time. [4] The vehicle charging system (106) of claim 1, further comprising: a cable (102) configured to be coupled to the external power source; and a detector coupled to the cable (102) and to the processor for detecting when the cable (102) is connected to the external energy source, wherein the processor is configured to start charging the battery assembly (108) when the predetermined charging initialization time is reached and when the detector indicates that the cable (102) is coupled to the external energy source. [5] The vehicle charging system (106) of claim 1, further comprising a sensor coupled to the battery assembly (108) and configured to determine the charge level of the battery assembly (108), wherein the processor is configured to start charging the battery assembly (108) when the predetermined charge initialization time is reached and when the sensor indicates that the charge level of the battery assembly (108) is below a predetermined threshold. [6] A vehicle charging system (106) employed in a vehicle (100) configured to be charged from an external power source, the vehicle charging system (106) comprising: a battery assembly (108); a control module coupled to the battery assembly (108) and monitoring the charge level of the battery assembly (108); a processor coupled to the battery assembly (108) and the control module; and a transceiver coupled to the processor; wherein the processor is configured to start charging the battery assembly (108) when the charge level of the battery assembly (108) is at least partially reduced and when a predetermined charge initialization time is reached; wherein the processor is configured to determine the charging initialization time based on data from an external source wirelessly received by the transceiver; wherein a charging termination time is further determined based on data from the external source, and wherein during charging of the vehicle, upon reaching the charging termination time, it is determined whether the charging level of the battery assembly (108) is less than or equal to a minimum charging threshold, and if so, the charging is not terminated. [7] The vehicle charging system (106) of claim 6, further comprising a telematics module (124) coupled to the processor, the processor configured to receive data from the telematics module (124) indicating the location of the vehicle (100). [8] The vehicle charging system (106) of claim 6, further comprising: a cable (102) configured to be coupled to the external power source; and a detector coupled to the cable (102) and to the processor for detecting when the cable (102) is connected to the external power source, wherein the processor is configured to start charging the battery assembly (108) when (1) the charge level of the battery assembly (108) is at least partially reduced, (2) a predetermined charge initialization time is reached, and (3) the detector indicates that the cable (102) is coupled to the external power source. [9] The vehicle charging system (106) of claim 6, further comprising a user interface (120) coupled to the processor, the user interface (120) configured to enable user selection of a charging mode. [10] The vehicle charging system (106) of claim 6, wherein the control module comprises an energy storage control module (114) coupled to the battery assembly (108) and configured to monitor operating parameters of the battery assembly (108). [11] A method for selecting the charging time of a battery assembly (108) from an external energy source, the battery assembly (108) being deployed in a vehicle (100) comprising a processor, a transceiver coupled to the processor, and a memory, the method comprising storing a predetermined charging initialization time in the memory; the current time is monitored by the processor; the predetermined charging initialization time is retrieved from the memory; and the charging of the battery assembly (108) is started when the current time reaches the predetermined charging initialization time, the method further comprising determining the charging initialization time from data from an external source wirelessly received via the transceiver; wherein a charging termination time is further determined based on data from the external source, and wherein during charging of the vehicle, upon reaching the charging termination time, it is determined whether the charging level of the battery assembly (108) is less than or equal to a minimum charging threshold, and if so, the charging is not terminated. [12] The method of claim 11, wherein the vehicle (100) includes a sensor coupled to the processor and the battery assembly (108) for indicating when the battery assembly (108) is coupled to the external power source, the method further comprising initiating charging of the battery assembly (108) when the current time reaches the predetermined charge initialization time and when the sensor indicates that the battery assembly (108) is coupled to the external power source. [13] The method of claim 11, wherein the vehicle (100) includes a sensor coupled to the processor and the battery assembly (108) for determining the charge level of the battery assembly (108), the method further comprising initiating charging of the battery assembly (108) when the current time reaches the predetermined charge initialization time and when the sensor indicates that the charge level of the battery assembly (108) is reduced below a predetermined threshold. [14] The method of claim 11, wherein the vehicle (100) comprises a user interface (120) coupled to the processor, the method further comprising receiving a user input from the user interface (120) indicating a desired charging initialization time. [15] The method of claim 11, wherein the vehicle (100) comprises a user interface (120) coupled to the processor and configured to enable selection of a default charging mode, the method further comprising initiating charging of the battery assembly (108) when the default charging mode is selected. [16] The method of claim 11, wherein the external source data includes an associated charging initialization time.

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