Charging device and methods for controlling a charging device

A charging device for use with an electric vehicle including a power storage device. The charging device includes a power conduit configured to electrically couple the power storage device to the charging device. The charging device includes a first protection device configured to electrically isolate the charging device from the power storage device if a current flowing through the power conduit exceeds a current limit. The charging device also includes a controller configured to control the current flowing through the power conduit if the current flowing through the power conduit causes an integration threshold to be exceeded, wherein the integration threshold is representative of a predetermined amount of current that is enabled to flow through the power conduit over a predetermined period of time.

BACKGROUND OF THE INVENTION

The present application relates generally to charging devices and, more particularly, to a charging device and methods for controlling a charging device.

As electric vehicles and/or hybrid electric vehicles have gained popularity, an associated need to accurately manage delivery of electrical energy to such vehicles has increased. Moreover, a need to provide safe and efficient charging devices or stations has been created by the increased use of such vehicles.

At least some known charging stations include a power cable or other conductor that may be removably coupled to the electric vehicle. The charging stations receive electricity from an electric utility distribution network or another electricity source, and deliver electricity to the electric vehicle through the power cable. At least some known charging stations and/or electric vehicles are designed or rated to operate at a predefined current amplitude. However, one or more components within the charging station and/or within the electric vehicle may fail or exhibit abnormal behavior. Such failures and/or abnormal behavior may cause the current transmitted through the power cable to exceed the rated current of the charging station and/or the electric vehicle.

To protect components within the charging station and/or the electric vehicle from excessive current, at least some known charging stations include at least one protective device coupled to the power cable. If excessive current is transmitted through the power cable, the protective device electrically decouples the charging station from the electric vehicle. However, after such protective devices are activated, a maintenance technician may be required to visit the charging station to reset or replace the protective device and restore the charging capability of the station. Such visits may be costly and/or an undesirable amount of time may pass before a technician visit may be arranged.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a charging device for use with an electric vehicle including a power storage device is provided that includes a power conduit configured to electrically couple the power storage device to the charging device. The charging device includes a first protection device configured to electrically isolate the charging device from the power storage device if a current flowing through the power conduit exceeds a current limit. The charging device also includes a controller configured to control the current flowing through the power conduit if the current flowing through the power conduit causes an integration threshold to be exceeded, wherein the integration threshold is representative of a predetermined amount of current that is enabled to flow through the power conduit over a predetermined period of time.

In another embodiment, a charging device for use with an electric vehicle including a power storage device is provided that includes a power conduit configured to electrically couple the power storage device to the charging device. The charging device includes a first protection device configured to electrically isolate the charging device from the power storage device if a current flowing through the power conduit exceeds a current limit. The charging device also includes a controller configured to control the current flowing through the power conduit if a temperature within the charging device exceeds a predetermined threshold.

In yet another embodiment, a method of controlling a charging device is provided that includes supplying current to a power storage device of an electric vehicle using the charging device and measuring at least one of a temperature within the charging device and a current flowing through the charging device. The current supplied to the power storage device is adjusted based on at least one of the measured temperature and the measured current.

In a further embodiment, a system is provided for use in charging a power storage device of an electric vehicle using current received from an electric power source. The system includes a charging device including a power conduit configured to receive current from the electric power source and to provide the current to the power storage device, and a first protection device configured to electrically isolate the charging device from the power storage device if a current flowing through the power conduit exceeds a current limit. The system also includes a controller configured to control the current flowing through the power conduit based on at least one of a temperature within the charging device and the current flowing through the power conduit.

DETAILED DESCRIPTION OF THE INVENTION

In some embodiments, the term “electric vehicle” refers generally to a vehicle that includes one or more electric motors that are used for propulsion. Energy used to propel electric vehicles may come from various sources, such as, but not limited to, an on-board rechargeable battery and/or an on-board fuel cell. In one embodiment, the electric vehicle is a hybrid electric vehicle, which captures and stores energy generated, for example, by braking. Moreover, a hybrid electric vehicle uses energy stored in an electrical source, such as a battery, to continue operating when idling to conserve fuel. Some hybrid electric vehicles are capable of recharging the battery by plugging into a power receptacle, such as a power outlet. Accordingly, the term “electric vehicle” as used herein may refer to a hybrid electric vehicle or any other vehicle to which electrical energy may be delivered, for example, via the power grid.

FIG. 1illustrates an exemplary system100for use in charging, or providing electricity to, an electric vehicle102. In an exemplary embodiment, system100includes a charging device104coupled to electric vehicle102. In an exemplary embodiment, electric vehicle102includes at least one power storage device106, such as a battery and/or any other storage device, coupled to a motor108. Moreover, in an exemplary embodiment, electric vehicle102includes a vehicle controller110coupled to power storage device106.

In an exemplary embodiment, charging device104is removably coupled to power storage device106and to vehicle controller110by at least one power conduit112. Alternatively, charging device104may be coupled to power storage device106and/or vehicle controller110by any other conduit or conduits, and/or charging device104may be coupled to vehicle controller110by a wireless data link (not shown). In an exemplary embodiment, power conduit112includes at least one conductor (not shown) for supplying electricity to power storage device106and/or to any other component within electric vehicle102, and at least one conductor (not shown) for transmitting data to, and receiving data from, vehicle controller110and/or any other component within electric vehicle102. Alternatively, power conduit112may include a single conductor that transmits and/or receives power and/or data, or any other number of conductors that enables system100to function as described herein. Moreover, in an exemplary embodiment, charging device104is coupled to an electric power source114, such as a power grid of an electric utility company, a generator, a battery, and/or any other device or system that provides electricity to charging device104.

In an exemplary embodiment, charging device104is coupled to at least one server116through a network, such as the Internet, a local area network (LAN), a wide area network (WAN), and/or any other network or data connection that enables charging device104to function as described herein. Server116, in an exemplary embodiment, communicates with charging device104, for example, by transmitting a signal to charging device104to authorize payment and/or delivery of electricity to power storage device106, to access customer information, and/or to perform any other function that enables system100to function as described herein.

In an exemplary embodiment, server116and vehicle controller110each include at least one processor and at least one memory device. The processors each include any suitable programmable circuit which may include one or more systems and microcontrollers, microprocessors, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), programmable logic circuits (PLC), field programmable gate arrays (FPGA), and any other circuit capable of executing the functions described herein. The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the term “processor.” The memory devices each include a computer readable medium, such as, without limitation, random access memory (RAM), flash memory, a hard disk drive, a solid state drive, a diskette, a flash drive, a compact disc, a digital video disc, and/or any suitable memory device that enables the processors to store, retrieve, and/or execute instructions and/or data.

During operation, in an exemplary embodiment, a user couples power storage device106to charging device104with power conduit112. The user may access a user interface (not shown inFIG. 1) of charging device104to enter information, such as payment information, and/or to initiate power delivery to power storage device106. Charging device104is configured to communicate with server116, for example, to authenticate the user, to process the payment information, and/or to approve or authorize the power delivery. If charging device104receives a signal from server116that indicates approval or authorization to deliver power to power storage device106, charging device104receives power from electric power source114and provides the power to power storage device106through power conduit112. Charging device104communicates with vehicle controller110wirelessly, through power conduit112, and/or through any other conduit, to control and/or to monitor the delivery of power to power storage device106. For example, vehicle controller110may transmit signals to charging device104indicating a charge level of power storage device106and/or a desired amount and/or rate of power to be provided by charging device104. Moreover, charging device104may transmit signals to vehicle controller110indicating an amount and/or rate of electricity being delivered to power storage device106. Additionally or alternatively, charging device104and/or vehicle controller110may transmit and/or receive any other signals or messages that enable system100to function as described herein. When power storage device106has been charged to a desired level, charging device104ceases delivering power to power storage device106and the user disengages power conduit112from power storage device106.

FIG. 2is a block diagram of an exemplary charging device104that may be used with system100(shown inFIG. 1). In an exemplary embodiment, charging device104includes a controller200that includes a processor202and a memory device204. As described more fully herein, controller200is coupled to a network interface206, to a display208, to a user interface210, to a vehicle communication module212, to a temperature sensor214, and to a current control module216. Moreover, as described more fully herein, controller200controls and/or adjusts the current flowing through power conduit112if a temperature within charging device104exceeds a predetermined temperature threshold and/or if the current flowing through power conduit112exceeds a predetermined current threshold.

Processor202includes any suitable programmable circuit which may include one or more systems and microcontrollers, microprocessors, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), programmable logic circuits (PLC), field programmable gate arrays (FPGA), and any other circuit capable of executing the functions described herein. The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the term “processor.” Memory device204includes a computer readable medium, such as, without limitation, random access memory (RAM), flash memory, a hard disk drive, a solid state drive, a diskette, a flash drive, a compact disc, a digital video disc, and/or any suitable device that enables processor202to store, retrieve, and/or execute instructions and/or data.

Network interface206, in an exemplary embodiment, transmits and receives data between controller200and a remote device or system, such as server116(shown inFIG. 1). In an exemplary embodiment, network interface206communicates with server116and controller200using any suitable communication protocol, such as a wired and/or a wireless Ethernet protocol.

In an exemplary embodiment, display208may include a vacuum fluorescent display (VFD) and/or one or more light-emitting diodes (LED). Additionally or alternatively, display208may include, without limitation, a liquid crystal display (LCD), a cathode ray tube (CRT), a plasma display, and/or any suitable visual output device capable of displaying graphical data and/or text to a user. In an exemplary embodiment, a charging status of power storage device106(shown inFIG. 1), payment information, user authentication information, and/or any other information may be displayed to a user on display208.

User interface210includes, without limitation, a keyboard, a keypad, a touch-sensitive screen, a scroll wheel, a pointing device, a barcode reader, a magnetic card reader, a radio frequency identification (RFID) card reader, an audio input device employing speech-recognition software, and/or any suitable device that enables a user to input data into charging device104and/or to retrieve data from charging device104. In an exemplary embodiment, the user may input user authentication information and/or payment information using user interface210. Moreover, the user may operate user interface210to initiate and/or terminate the delivery of power to power storage device106.

In an exemplary embodiment, vehicle communication module212is coupled to vehicle controller110(shown inFIG. 1) by power conduit112or by any other conduit that enables vehicle communication module212to function as described herein. Vehicle communication module212transmits data to, and receives data from, vehicle controller110using a suitable protocol, such as power line communication (PLC), a serial communication protocol, and/or any other protocol that enables vehicle communication module212to function as described herein. In an exemplary embodiment, vehicle communication module212transmits at least one signal (hereinafter referred to as a “current control signal”) to vehicle controller110for use in controlling and/or adjusting an amount of current that power storage device106draws from charging device104. More specifically, controller200determines an amount of current for power storage device106to draw from charging device104. Controller200transmits one or more signals representative of the determined amount of current to vehicle communication module212. In one embodiment, vehicle communication module212uses pulse width modulation and/or adjusts a duty cycle of the current control signal to notify vehicle controller110of the determined amount of current to draw from charging device104. Alternatively, vehicle communication module212may use any other signal or signaling method to notify vehicle controller110of the determined amount of current to draw from charging device104. The current control signal received from vehicle communication module212triggers vehicle controller110to draw the determined amount of current from charging device104.

In an exemplary embodiment, temperature sensor214is positioned within charging device104and is coupled to controller200. Alternatively, temperature sensor214is integrated within controller200, within any other component of charging device104, and/or is positioned in any other location that enables temperature sensor214to function as described herein. In an exemplary embodiment, temperature sensor214detects and/or measures the temperature within charging device104. Temperature sensor214provides a signal representative of the measured and/or detected temperature (hereinafter referred to as a “temperature measurement”) to controller200.

In an exemplary embodiment, current control module216is coupled to an input end218of a power conduit112and to an output end220of power conduit112. Input end218is coupled to a power source, such as electric power source114(shown inFIG. 1), and output end220is coupled to a load, such as power storage device106. More specifically, in an exemplary embodiment, input end218is coupled to a single phase of a three phase alternating current (AC) power source, such as electric power source114. Alternatively, input end218may be coupled to a direct current (DC) power source or to two or three phases of an AC power source. Moreover, in an exemplary embodiment, current control module216includes at least one current protection device222, at least one secondary protection device224, and at least one current sensor226. Current protection device222, in an exemplary embodiment, is activated to electrically isolate input end218from output end220if the current flowing through power conduit112exceeds a predetermined threshold or current limit. More specifically, current protection device222activates, or “trips,” when the current flowing through power conduit112exceeds a rated current limit of current protection device222. When current protection device222activates or trips, current is prevented from flowing through power conduit112(i.e., input end218is electrically isolated from output end220). In an exemplary embodiment, current protection device222is a circuit breaker. Alternatively, current protection device222may be a fuse, a relay, and/or any other device that enables current protection device222to function as described herein.

Secondary protection device224, in an exemplary embodiment, is a contactor224coupled to current protection device222by power conduit112. Moreover, contactor224is coupled to, and is controlled by, controller200. In an exemplary embodiment, controller200operates contactor224to interrupt the current flowing through power conduit112if the current exceeds a predetermined threshold, as more fully described herein, such that input end218is electrically isolated from output end220. As such, by operating or activating contactor224, controller200prevents current from flowing to power storage device106. Moreover, contactor224is operated to interrupt the current flowing through power conduit112before current protection device222is activated such that current protection device222may be preserved as a backup protection device. Contactor224may be reset by controller200after contactor224has been activated such that input end218is electrically reconnected to output end220. As such, the use of contactor224may reduce the number of maintenance visits required to restore power delivery from charging device104after excessive current has been transmitted through charging device104.

At least one current sensor226measures and/or detects the current transmitted through power conduit112during operation of charging device104. In an exemplary embodiment, a plurality of current sensors226include at least one current transformer228that detects one or more ground faults and at least one current transformer230that detects and/or measures the current transmitted through power conduit112. Current sensors226transmit signals representative of the measured and/or detected current (hereinafter referred to as “current measurements”) to controller200.

FIG. 3is a flow diagram of an exemplary method300for controlling a charging device, such as charging device104(shown inFIG. 2). In an exemplary embodiment, method300includes a plurality of instructions stored within memory device204, and is at least partially executed by processor202(both shown inFIG. 2).

Charging device104is electrically coupled to an electric vehicle, such as electric vehicle102, by power conduit112(both shown inFIG. 1). More specifically, charging device104is coupled to power storage device106(shown inFIG. 1) of electric vehicle102by power conduit112. Power storage device106is charged302at a predetermined current rate or amplitude (hereinafter referred to as a “current charging rate”) based on a current capacity or rating of power storage device106and/or a current capacity or rating of one or more components of current control module216(shown inFIG. 2). For example, if current protection device222is rated at 16 Amps (A), and no other component coupled to power conduit112has a lower current rating, charging device104supplies a predetermined current charging rate of approximately 16 A to power storage device106. Alternatively, power storage device106is charged302with any other current rate that enables method300to function as described herein. A temperature within charging device104is measured304, for example, by temperature sensor214(shown inFIG. 2). Controller200determines306whether the temperature within charging device104exceeds a predetermined temperature threshold. In an exemplary embodiment, the predetermined temperature threshold is selected such that the current rating of current protection device222, contactor224, and/or any other component of current control module216is maintained. In one embodiment, the predetermined temperature threshold is about 30 degrees Centigrade. Alternatively, the predetermined temperature threshold is any other temperature that enables method300to function as described herein.

If the determined temperature does not exceed the temperature threshold, method300continues charging302power storage device106at the predetermined current charging rate. If, however, the determined temperature exceeds the temperature threshold, method300adjusts308the current charging rate to a second current charging rate such that power storage device106is charged, or supplied with current, at the second current charging rate. In an exemplary embodiment, the second current charging rate is based on the determined temperature within charging device104. In one embodiment, as the determined temperature progressively increases above the temperature threshold, the second current charging rate progressively decreases below the predetermined current charging rate. Alternatively, the second charging rate may have any linear or nonlinear relationship to the determined temperature such that the second current charging rate decreases at a linear or nonlinear rate as the determined temperature increases above the temperature threshold.

In one embodiment, the second current charging rate decreases in accordance with a degradation of the current rating, or a derating curve, of current protection device222as the determined temperature progressively increases above the temperature threshold. Moreover, in a further embodiment, controller200references and/or interpolates values received from a lookup table or other current rating or derating reference to determine the reduction in the second current charging rate at the determined temperature. The lookup table or other reference may be stored in memory device204and/or within any other device that enables the second current charging rate to be determined. Accordingly, by decreasing the charging current rate as the temperature increases within charging device104, method300enables current protection device222to avoid being activated by excessive current. As such, method300may reduce a number of maintenance events that may otherwise be required to reset current protection device222as the temperature within charging device104increases.

FIG. 4is a flow diagram of another exemplary method400for controlling a charging device, such as charging device104(shown inFIG. 2). In an exemplary embodiment, method400includes a plurality of instructions stored within memory device204, and is at least partially executed by processor202(both shown inFIG. 2). Moreover, in an exemplary embodiment, method300(shown inFIG. 3) is used together with method400.

In an exemplary embodiment, charging device104is electrically coupled to an electric vehicle, such as electric vehicle102, by power conduit112(both shown inFIG. 1). More specifically, charging device104is coupled to power storage device106(shown inFIG. 1) of electric vehicle102by power conduit112. Power storage device106is charged402at a predetermined current rate or amplitude (hereinafter referred to as a “current charging rate”) based on a current capacity or rating of power storage device106and/or a current capacity or rating of one or more components of current control module216(shown inFIG. 2) in a similar manner as described above with reference toFIG. 3. As such, charging device104supplies the predetermined current charging rate to power storage device106.

An amplitude of the current supplied to power storage device106is measured404by current sensor226(shown inFIG. 2) and/or by any other current sensor. Controller200determines406whether the amplitude of the measured current exceeds a predetermined first current threshold. In an exemplary embodiment, the first current threshold is approximately 1.25 times the rated current of current protection device222. Alternatively, the first current threshold may be 1.13 times the rated current, or any other rate or level that enables method400to function as described herein.

The measured current may exceed the first current threshold, for example, when a component within electric vehicle102, such as power storage device106, is drawing excessive current due to a fault within electric vehicle102or due to any other abnormal state of electric vehicle102and/or charging device104. If the measured current exceeds the first current threshold, an increment value is determined408based on the measured current. In an exemplary embodiment, the increment value is determined408or selected based on an amount that the amplitude of the measured current exceeds the first current threshold. In one embodiment, the increment value is exponentially proportional to the measured current. Alternatively, the increment value has any other relationship to the measured current that enables method400to function as described herein. The increment value may be selected by referencing and/or interpolating values received from a lookup table stored within memory device204, and/or from any other data source that enables method400to function as described herein.

In an exemplary embodiment, an integration value is incremented410by the increment value, and controller200determines412whether the integration value exceeds a predetermined integration threshold. In an exemplary embodiment, the integration value, the increment values, and the integration threshold are stored within memory device204and/or within processor202(shown inFIG. 2). The integration value represents an amount of current that has accumulated above the first current threshold over a period of time. As used herein, the terms “accumulate” and “accumulation” refer to an aggregation of values, such as values representative of a current amplitude, that are measured by a sensor, such as current sensor226(shown inFIG. 2). In one embodiment, processor202receives periodic current measurements from current sensor226and increments410the integration value by an amount (i.e., the increment value) representative of the amplitude of each current measurement in excess of the first current threshold. The integration threshold represents a predetermined maximum accumulation of current over a predetermined period of time that may be sustained, or that is enabled to flow through power conduit112, for example, without substantial damage to components of electric vehicle102and/or charging device104. If the integration value exceeds the integration threshold, processor202activates414a current protection device, such as contactor224. More specifically, processor202opens contactor224to electrically isolate input end218from output end220of power conduit112(all shown inFIG. 2). In one embodiment, processor202may reset contactor224(e.g., by closing contactor224) to electrically couple input end218and output end220if power storage device106is decoupled from power conduit112and/or if the faulty condition is corrected or removed.

The integration value, in an exemplary embodiment, is initialized to zero at a beginning of charging device104operation, and is adjusted based on the increment value. Alternatively, the integration value may be initialized to any other value that enables method400to function as described herein. Moreover, in an exemplary embodiment, the increment values and the integration threshold are selected such that contactor224is activated before current protection device222is activated.

In an embodiment, contactor224is activated414when the supplied current exceeds the first current threshold for a predetermined amount of time, such as the amount of time it takes for the integration value to increase about the first current threshold. Preferably, the predetermined amount of time varies based on the amplitude of the supplied current. In an embodiment, as the amplitude of the supplied current progressively increases above the first current threshold, the amount of time that elapses before contactor224is activated414progressively decreases (i.e., increment values are progressively increased such that the integration value reaches the integration threshold more rapidly).

If, however, the integration threshold is not exceeded by the integration value, the current supplied to power storage device106is measured404and controller200determines406whether the measured current exceeds the first current threshold, as described above. If the measured current does not exceed the first current threshold, controller200determines416whether the measured current is less than a second current threshold. In an exemplary embodiment, the second current threshold is lower than the first current threshold. More specifically, in an exemplary embodiment, the second current threshold is approximately equal to the rated current of current protection device222. Alternatively, the second current threshold may be any other rate or level that enables method400to function as described herein. If the measured current is greater than or equal to the second current threshold (but not greater than the first current threshold), no adjustment is made to the integration value (i.e., the integration value is maintained at its current value), and method400returns to measuring404the supplied current. If, however, the measured current is less than the second current threshold, controller200determines418whether the integration value is greater than zero or any other lower limit for the integration value. If the integration value is less than or equal to the lower limit, the amplitude of the current supplied to power storage device106is measured404as described above. If the integration value is greater than the lower limit, a decrement value is determined420, and the integration value is decremented422by the decrement value. In one embodiment, the integration value is not decremented422below the lower limit. Method400returns to measuring404the supplied current.

In an exemplary embodiment, the decrement value is determined420based on the amplitude of the measured current. In one embodiment, the decrement value is exponentially proportional to the measured current. Alternatively, the decrement value has any other relationship to the measured current that enables method400to function as described herein. The decrement value may be selected by referencing and/or interpolating values received from a lookup table, and/or by any other data source that enables method400to function as described herein.

As described herein, a robust and effective charging device is provided. The charging device includes a current protection device and a secondary protection device. The current protection device electrically isolates an input end of a power conduit from an output end of the power conduit if the current channeled through the power conduit exceeds a current limit of the current protection device. The secondary protection device controls the current transmitted through the power conduit if the current exceeds a predetermined threshold and/or if the temperature within the charging device exceeds a predetermined threshold. A controller within the charging device may reset the secondary protection device to restore current flow through the power conduit. As such, a maintenance technician may not be needed to be physically present at the charging device to reset the current protection device if excessive current has been transmitted through the power conduit. Moreover, current protection device and secondary protection device may protect components within the charging device and/or components within the electric vehicle from damage resulting from excessive current.

A technical effect of the device and methods described herein includes at least one of (a) supplying current to a power storage device of an electric vehicle using a charging device; (b) measuring at least one of a temperature within a charging device and a current flowing through the charging device; and (c) adjusting a current supplied to a power storage device of an electric vehicle based on at least one of a measured temperature and a measured current.

Exemplary embodiments of a charging device and methods of controlling a charging device are described above in detail. The charging device and methods are not limited to the specific embodiments described herein, but rather, components of the charging device and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the charging device may also be used in combination with other power systems and methods, and is not limited to practice with only the electric vehicle as described herein. Rather, an exemplary embodiment can be implemented and utilized in connection with many other power system applications.