DYNAMIC LOAD MANAGEMENT FOR ELECTRIC VEHICLE CHARGING

A system for charging an electric vehicle in a facility includes a current sensor adapted to obtain an input current signal for a power source in the facility. An electric vehicle supply equipment (EVSE) is configured to charge the electric vehicle through the power source based at least partially on a control pilot signal. A controller has a processor and tangible, non-transitory memory on which instructions are recorded for dynamically adjusting the control pilot signal based on the input current signal. The control pilot signal is set to a predefined maximum when the input current signal is less than a main circuit breaker rating of the facility. The controller is configured to reduce the control pilot signal from the predefined maximum when the input current signal is at or above the main circuit breaker rating.

INTRODUCTION

The present disclosure relates to dynamic load management for charging an electric vehicle. The use of purely and partially electric vehicles, such as battery electric vehicles, range-extended electric vehicles, hybrid electric vehicles, and fuel cell hybrid electric vehicles, has increased greatly over the last few years. Electric vehicles include a rechargeable energy storage unit, such as a high voltage battery having a number of battery cells, which requires periodic recharging. The charging may be done at a public or private charging station. Many places, such as dwellings, may not be suitable for charging an electric vehicle without an extensive utility service upgrade. For example, a utility service upgrade may involve expensive and laborious activities, such as trenching and restoring uprooted lawn, cement, trees and other items to install wires rated for higher current.

SUMMARY

Disclosed herein is a system for charging an electric vehicle in a facility. An electric vehicle supply equipment (EVSE) is configured to connect the electric vehicle to a power source in the facility. The EVSE is adapted to charge the electric vehicle based at least partially on a control pilot signal. The system includes a current sensor adapted to obtain an input current signal for the power source. A controller is in communication with the EVSE. The controller has a processor and tangible, non-transitory memory on which instructions are recorded for dynamically adjusting the control pilot signal based on the input current signal.

The controller is configured to obtain a plurality of factors, including an EVSE circuit breaker rating and a main circuit breaker rating of the facility. The control pilot signal is set to a predefined maximum when the input current signal is less than the main circuit breaker rating of the facility. The controller is configured to reduce the control pilot signal from the predefined maximum when the input current signal is at or above the main circuit breaker rating of the facility.

In some embodiments, the facility is a dwelling. The plurality of factors includes an available ampacity for the EVSE. The controller may be adapted to adjust the control pilot signal to match the available ampacity for the EVSE when the input current signal is not available. In some embodiments, the predefined maximum corresponds to at about 80% of the EVSE circuit breaker rating. The controller may be embedded with the EVSE.

In one embodiment, the controller is adapted to reduce the control pilot signal from the predefined maximum, when the input current signal is at or above the main circuit breaker rating, in a curved or exponential fashion. In another embodiment, the controller is adapted to reduce the control pilot signal from the predefined maximum in a stepwise fashion. In yet another embodiment, the controller is adapted to reduce the control pilot signal from the predefined maximum in a linear fashion. The system may include a distribution panel having a plurality of circuit breakers corresponding to respective branch circuits around the facility, the current sensor being operatively connected to a portion of the distribution panel.

Disclosed herein is a method for charging an electric vehicle in a facility with a system having a controller with a processor and tangible, non-transitory memory. The method includes connecting an electric vehicle supply equipment (EVSE) between the electric vehicle and a power source in the facility, the EVSE being adapted to charge the electric vehicle based at least partially on a control pilot signal. A current sensor is connected to the power source. The method includes obtaining an input current signal for the power source, via the current sensor. A plurality of factors is obtained, including an EVSE circuit breaker rating and a main circuit breaker rating of the facility, via the controller. The method includes dynamically adjusting the control pilot signal based on the input current signal and the plurality of factors, via the controller, including setting the control pilot signal to a predefined maximum when the input current signal is less than the main circuit breaker rating of the facility. The control pilot signal is reduced to below the predefined maximum when the input current signal is at or above the main circuit breaker rating of the facility.

Representative embodiments of this disclosure are shown by way of non-limiting example in the drawings and are described in additional detail below. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the above-enumerated drawings. Rather, the disclosure is to cover modifications, equivalents, combinations, sub-combinations, permutations, groupings, and alternatives falling within the scope of this disclosure as encompassed, for instance, by the appended claims.

DETAILED DESCRIPTION

Referring to the drawings, wherein like reference numbers refer to like components,FIG.1schematically illustrates a system10for charging an electric vehicle12. The electric vehicle12may be purely or partially electric. The electric vehicle12may be a mobile platform, such as, but not limited to, a passenger car, sport utility vehicle, light truck, heavy duty vehicle, ATV, minivan, bus, transit vehicle, bicycle, robot, farm implement, sports-related equipment, boat, plane, train or other device. It is to be understood that the electric vehicle12may take many different forms and have additional components.

Referring toFIG.1, the electric vehicle12includes a rechargeable energy storage unit14, such as a high voltage battery having a number of battery cells. The rechargeable energy storage unit14may include battery cells of different chemistries, including but not limited to, lithium-ion, lithium-iron, nickel metal hydride and lead acid batteries. The electric vehicle12may include an additional power source (not shown), such as but not limited to, an internal combustion engine or a fuel cell.

The electric vehicle12is capable of utilizing an external source of power, e.g., a socket that connects to a power source or power grid to store electrical energy within its rechargeable energy storage unit14. Public charging stations are typically found street-side or at retail shopping centers, public facilities, and other parking areas. Charging stations are equipped with multiple connectors to be able to supply a wide variety of vehicles. However, places such as dwellings and commercial buildings, may not be suitable for charging an electric vehicle12without an extensive utility service upgrade.

Referring toFIG.1, the system10includes a controller C having at least one processor P and at least one memory M (or non-transitory, tangible computer readable storage medium) on which instructions may be recorded for executing a method100(described below with respect toFIG.2) for dynamically adjusting the load transferred from a power source18in a facility16to the electric vehicle12. The facility may be a dwelling (e.g., detached house, apartment building, condo etc.) or a commercial structure/building. The memory M can store controller-executable instruction sets, and the processor P can execute the controller-executable instruction sets stored in the memory M.

The system10allows the electric vehicle12to be charged in the facility16without requiring an extensive utility upgrade. Industry standards (e.g., NEC Article 220 Service Calculation) provide calculations for determining the required utility service rating (in amperes) based on the size of a home or commercial building and the appliances/devices that are installed within it. Upgrades (e.g., adding a high-power 19 kW EVSE) generally require replacement of the wires supplying electric power to the home and an electric panel rated for higher current.

Referring toFIG.1, the load is transferred via an electric vehicle supply equipment20, referred to herein as EVSE20. The EVSE20may include various types of coupling devices, attachments and connectors, such as element22and element24. In some embodiments, the EVSE20may be fixedly attached or “hardwired” to the facility16, eliminating the need for a plug and receptacle connection system to connect to the AC power supply of a home, for example. The EVSE20acts as a conduit for supplying electrical power to charge plug-in electric vehicles. The controller C may be embedded within the EVSE20. The system10provides a method100for automatic continuous adjustment of EVSE power throughout the charge cycle.

The EVSE20is configured to charge the electric vehicle12based at least partially on a control pilot signal. The control pilot signal is a signal from the EVSE20to the electric vehicle12indicating how much current the electric vehicle12is allowed to draw from the EVSE20. In other words, the control pilot signal is a communication line between the EVSE20and the electric vehicle12that can be updated frequently (as often as every 1 millisecond) for the purpose of communicating the maximum current that the electric vehicle12is allowed to consume from the EVSE20.

Referring toFIG.1, the power source18in the facility16may be a distribution panel30receiving power generated by an electrical grid or utility26. Power from the utility26is generally transferred through a network of power lines that connect to an individual facility16. The electricity first goes through an electric meter28and then passes through to the distribution panel30. The electric meter28measures how much electricity the facility16is using.

Referring toFIG.1, system10includes a current sensor40(shown with abbreviation “A” for ampere) configured to obtain an input current signal received by the power source18in the facility16. Where the facility16is a home, the input current signal reflects the total home input current. The input current signal is sent to the controller C, where it is used for dynamically adjusting the charging load for the electric vehicle12. The current sensor40may be operatively connected to a portion of the distribution panel30.

An example distribution panel230is shown inFIG.3. It is understood that other forms and structures may be employed in the distribution panel230. The distribution panel230ofFIG.3includes a main circuit breaker200, which may be a large two-pole circuit breaker that limits the amount of electricity coming in from outside to protect the circuits that it feeds. The main circuit breaker200identifies the amperage capacity of the distribution panel230. Referring toFIG.3, the distribution panel230includes a plurality of circuit breakers206corresponding to respective branch circuits around the facility16. For example, the plurality of circuit breakers206may respectively link to the laundry room, kitchen and main living area. The circuit breakers206are devices that automatically interrupt current flow when excessive current is detected. Each circuit breaker206has a reset switch208to allow the user to restore power to a branch circuit if the circuit breaker206has automatically shut off.

Referring toFIG.3, the current sensor240includes first and second portions242A,242B that engage with (e.g., by clipping onto) the incoming wires202and204, respectively, bringing power in from the electrical meter28(seeFIG.1). The first and second portions242A,242B of the current sensor240may connect via wires244A and244B, respectively, to an integrated processor246. Referring toFIG.3, multiple wires or bus bars210may be used to connect the various parts of the distribution panel230. Some of the bus bars210may be neutral and others may be grounding bus bars. By continuously adjusting EVSE power as other loads within the facility16turn on and off, via the controller C, it is possible for the EVSE20to provide as much power as possible without tripping the main circuit breaker200.

In some embodiments, the current sensor40(via the integrated processor246) transmits data to the controller C via a wireless network54to enable real-time monitoring of home energy consumption. This data is sent to the controller C to allow it to determine the present total load power in the home and make real-time adjustments to EVSE power when required, e.g., to prevent the total home load from exceeding available utility power.

Referring now toFIG.2, a flowchart of the method100stored on and executable by the controller C ofFIG.1is shown. Method100may be embodied as computer-readable code or instructions stored on and partially executable by the controller C ofFIG.1. Method100need not be applied in the specific order recited herein. Furthermore, it is to be understood that some steps may be eliminated. The method100may be dynamically executed. As used herein, the terms ‘dynamic’ and ‘dynamically’ describe steps or processes that are executed in real-time and are characterized by monitoring or otherwise determining states of parameters and regularly or periodically updating the states of the parameters during execution of a routine or between iterations of execution of the routine.

Per block102ofFIG.2, the method100includes obtaining a plurality of factors, including an EVSE circuit breaker rating (of an EVSE circuit breaker25, seeFIG.3, for the EVSE20, seeFIG.1) and a main circuit breaker rating (of the main circuit breaker200, seeFIG.1). The EVSE circuit breaker rating and the main circuit breaker rating respectively depend upon the characteristics of the EVSE20and the particulars of the power source18and/or the main circuit breaker200and are generally fixed.

The plurality of factors includes an available ampacity for the EVSE, which is the excess ampacity. The controller C is programmed to calculate the excess ampacity as the utility service rating minus the required facility ampacity. The required facility (e.g., home) ampacity is calculated per industry standard rules (e.g., NEC Article 220 rules) without regard to the particulars of the EVSE20. Ampacity is defined as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. The ampacity of a conductor depends on its ability to dissipate heat to the surrounding, and is a function of insulation temperature rating, the electrical resistance of the conductor material and the ambient temperature. The plurality of factors is stored in the controller C.

Advancing to block104ofFIG.2, the controller C is programmed to determine if the input current signal from the current sensor40is available. If the input current signal is not available, e.g., due to sensor failure (block104=NO), the method100advances to block106, where the control pilot signal (“CP” inFIG.2) is adjusted to match the available ampacity (from block102) for the EVSE20. If the input signal is available (block104=YES), the method100advances to block108.

Per block108ofFIG.2, the method100includes determining if the input current signal is less than the main circuit breaker rating (from block102) of the facility16. If so, (block108=YES), the method100advances to block110where the controller C is programmed to set the control pilot signal (“CP” inFIG.2) to a predefined maximum. In one embodiment, the predefined maximum is set to be between about 65% and 80% of the EVSE circuit breaker rating. For example, the predefined maximum may be about 80% of the EVSE circuit breaker rating.

If the input current signal is at or above the main circuit breaker rating, (block108=NO), the method100advances to block112. Per block112ofFIG.2, the controller C is programmed to reduce the control pilot signal to a value below the predefined maximum.FIG.4is a schematic graph showing an example control pilot signal300, with the vertical axis304indicating amplitude and the horizontal axis302indicating time. Referring toFIG.4, the control pilot signal300is set to a predefined maximum level306when the input current signal is below the main circuit breaker rating (at time to). At time t1, the input current signal increases to at least the main circuit breaker rating, leading the controller C to reduce the control pilot signal300to below the predefined maximum level306.

Referring toFIG.4, in one embodiment, the controller C may reduce the control pilot signal300from the predefined maximum level306in a stepwise fashion, by instantaneously dropping it to at least one intermediate level310prior to reducing the control pilot signal300to a lower level308at time t2. In another embodiment, the controller C may reduce the control pilot signal300in a linear fashion (as indicated by line312). In yet another embodiment, the reduction of the control pilot signal from the predefined maximum level306may be in a curved or exponential fashion (as indicated by line314).

From blocks106,110and112, the method100proceeds to block114. Per block114ofFIG.2, the controller C is programmed to determine if the charging has been completed to a satisfactory level. If so, the method100is ended. If not, the method100loops back to block104, as indicated by line116. If the current sensor signal is subsequently lost or unavailable during the charging (block104), controller C sets the control pilot signal to the available ampacity (e.g., per NEC Article 220). This is done to allow charging to continue at a slower rate without potentially causing the main circuit breaker200to trip.

Referring toFIG.1, data from the controller C may be shared with a mobile application50and/or onboard vehicle controller. The mobile application50may be embedded in a smart phone belonging to a user of the electric vehicle12. The mobile application50may be plugged or otherwise linked to the electric vehicle12. The circuitry and components of a mobile application50(“apps”) available to those skilled in the art may be employed.

The controller C ofFIG.1may access data or information from a remotely located or “off-board” cloud computing service, referred to herein as cloud unit52. The cloud unit52may include one or more servers hosted on the Internet to store, manage, and process data, maintained by an organization, such as for example, a research institute or a company. Referring toFIG.1, the controller C may be configured to communicate with the cloud unit52via a wireless network54.

The wireless network54ofFIG.1may be a short-range network or a long-range network. The wireless network54may be a communication BUS, which may be in the form of a serial Controller Area Network (CAN-BUS). The wireless network54may incorporate a Bluetooth™ connection, a Wireless Local Area Network (LAN) which links multiple devices using a wireless distribution method, a Wireless Metropolitan Area Network (MAN) which connects several wireless LANs or a Wireless Wide Area Network (WAN). Other types of connections may be employed.

In summary, the system10(via execution of method100) provides the ability to continuously monitor the total incoming load (e.g., total home load) and dynamically adjust the charge power of the EVSE20, working at a higher average power without tripping the main circuit breaker200of the facility16. The system10enables faster charging for an electric vehicle12, without requiring an electric utility service upgrade to existing homes or commercial buildings. For example, an owner of the electric vehicle12may plug into a suitable EVSE20at home, and the electric vehicle12may recharge overnight.

The controller C ofFIG.1may be an integral portion of, or a separate module operatively connected to, other controllers of the vehicle12. The controller C ofFIG.1includes a computer-readable medium (also referred to as a processor-readable medium), including a non-transitory (e.g., tangible) medium that participates in providing data (e.g., instructions) that may be read by a computer (e.g., by a processor of a computer). Such a medium may take many forms, including, but not limited to, non-volatile media and volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random-access memory (DRAM), which may constitute a main memory. Such instructions may be transmitted by one or more transmission media, including coaxial cables, copper wire and fiber optics, including the wires that comprise a system bus coupled to a processor of a computer. Some forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, other magnetic medium, a CD-ROM, DVD, other optical medium, a physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, other memory chip or cartridge, or other medium from which a computer can read.

Look-up tables, databases, data repositories or other data stores described herein may include various kinds of mechanisms for storing, accessing, and retrieving various kinds of data, including a hierarchical database, a set of files in a file system, an application database in a proprietary format, a relational database energy management system (RDBMS), etc. Each such data store may be included within a computing device employing a computer operating system such as one of those mentioned above and may be accessed via a network in one or more of a variety of manners. A file system may be accessible from a computer operating system and may include files stored in various formats. An RDBMS may employ the Structured Query Language (SQL) in addition to a language for creating, storing, editing, and executing stored procedures, such as the PL/SQL language mentioned above.