POWER SUPPLY SYSTEM AND VEHICLE

A power supply system includes a vehicle, and a power feeding device for receiving power from the vehicle and feeding the received power to a load external to the vehicle. The vehicle includes a power generation unit, a power feeding unit for receiving power from the power generation unit and supplying the received power to the power feeding device, a storage unit for storing therein a specification of power supplied from an external power supply to the load, and a control device that controls the power feeding unit to convert power that is received from the power generation unit into power to drive the load, as based on the specification of the supplied power that is stored in the storage unit, once the external power supply has failed.

DESCRIPTION OF EMBODIMENTS

Hereinafter reference will be made to the drawings to describe the present invention in embodiments more specifically. In the figures, identical or corresponding components are identically denoted.

FIG. 1schematically shows a configuration of a power supply system according to an embodiment of the present invention.

With reference toFIG. 1, the power supply system includes a vehicle10, a charging stand200, a home energy management system (HEMS)300, a load device400, a power supply500external to vehicle10(hereinafter also referred to as “external power supply”), and a switchboard510.

The present invention in the embodiment provides vehicle10as a so called plug-in type electrically powered vehicle capable of electrically charging an in-vehicle power storage device via external power supply500. Note that the electrically powered vehicle may not be limited in configuration in particular as long as it can travel on power received from the in-vehicle power storage device. Vehicle10includes a hybrid vehicle, an electric vehicle, a fuel cell powered vehicle and the like for example.

Vehicle10includes a power storage device100, a driving force output device135, an electronic control unit (ECU)130for generally controlling the operation of vehicle10, a communication unit140, and a storage unit145(seeFIG. 2).

Power storage device100is a rechargeably configured power reservoir element, and representatively a lithium ion battery, a nickel metal hydride battery or a similar rechargeable battery. Alternatively, an electric double layer capacitor or a similar power reservoir element other than a battery may configure power storage device100.FIG. 1shows a configuration of a system of vehicle10that is relevant to controlling electrically charging and discharging power storage device100. Power storage device100is provided with a battery sensor (not shown) for sensing the voltage and current of power storage device100.

A monitoring unit105(seeFIG. 2) detects a value indicative of a state of power storage device100based on an output of the battery sensor provided for power storage device100. In other words, the value includes the voltage and/or current of power storage device100. As described above, power storage device100is representatively a rechargeable battery, and accordingly, the voltage and current of power storage device100will hereinafter also be referred to as battery voltage and battery current, respectively. Furthermore, the battery voltage and the battery current will hereinafter also be referred to as “battery data” collectively.

Driving force output device135uses power stored in power storage device100to generate force to drive vehicle10. Specifically, driving force output device135operates in response to a drive instruction received from ECU130to generate force for driving vehicle10and outputs the generated driving force to a driving wheel (not shown) of vehicle10. Note that the drive instruction is a control instruction generated based on force requested to drive or brake the vehicle while vehicle10is travelling. Specifically, ECU130calculates force required for the entirety of vehicle10to drive or brake the vehicle in response to the state of vehicle10as a vehicle, the driver's operation such as how much the accelerator pedal is stepped on, the position of the shift lever, how much the brake pedal is stepped on, and the like. Then, ECU130generates an instruction to drive driving force output device135to implement power requested to drive or brake the vehicle.

Furthermore, when driving force output device135receives an instruction from ECU130to generate power, it generates power to be supplied to load device400external to the vehicle and outputs the generated power to a power feeding unit120.

Note that the instruction to generate power is a control instruction issued to generate power supplied to load device400in an emergency power generation mode described later.

With reference toFIG. 2, vehicle10(FIG. 1) will further be described in configuration.

With reference toFIG. 2, driving force output device135includes a power conversion unit (a power control unit: PCU)150, motor generators160,165, a driving force transmission gear175, an engine170, and a driving wheel180.

PCU150is connected to power storage device100. Power storage device100supplies PCU150with power for generating force to drive vehicle10. Furthermore, power storage device100stores power generated by motor generators160,165. Specifically, PCU150includes a converter152, inverters154,156, and capacitors C1and C2.

Converter152operates in response to a control signal PWC received from ECU130to perform voltage conversion between power lines PL1and NL1and power lines PL2and NL1.

Inverters154,156are connected to power lines PL2and NL1in parallel. Inverters154,156operate in response to control signals PMI1and PMI2received from ECU130to convert direct current (dc) power that is received from converter152into alternating current (ac) power to drive motor generators160,165, respectively.

Capacitor C1is provided between power lines PL1and NL1, and decreases voltage variation caused between power lines PL1and NL1.

Motor generator160,165is an ac rotating electric machine, and for example is a permanent-magnet type, synchronous motor having a rotor with a permanent magnet embedded therein.

Motor generators160,165output torque, which is in turn transmitted to driving wheel180via driving force transmission gear175configured of a speed reducer, a driving force split device and the like and thus causes vehicle10to travel. When vehicle10is braked regeneratively, motor generator160,165can generate power by the torque of driving wheel180. Then, the generated power is converted by PCU150into power charged to power storage device100.

Furthermore, motor generators160,165are also coupled with engine170via driving force transmission gear175. Then, motor generators160,165and engine170are cooperatively operated by ECU130to generate force required to drive the vehicle. Furthermore, motor generators160,165can generate power by the rotation of engine170, and the generated power can be used to electrically charge power storage device100. Note that in the present embodiment, motor generator165is used exclusively as an electric motor for driving wheel180whereas motor generator160is used exclusively as a power generator driven by engine170for the sake of illustration.

Note that whileFIG. 2illustrates a configuration provided with two motor generators, the number of the motor generators is not limited thereto, and a single motor generator or three or more motor generators may be provided.

Furthermore, while the present embodiment is described with vehicle10illustrated as a hybrid vehicle, as described above, vehicle10is not limited in configuration as long as it is a vehicle that can use power generated by the power generator driven by engine170and/or power output from power storage device100to supply power to a load device external to the vehicle. In other words, vehicle10includes a hybrid vehicle which generates force via an engine and an electric motor to drive the vehicle, as shown inFIG. 2, and in addition thereto, a vehicle provided with a power generator which does not generate force to drive the vehicle but generates power via an engine, an electric vehicle or a fuel cell powered vehicle which does not have an engine mounted therein, and the like.

Vehicle10further includes an inlet112provided in the body of vehicle10, a charging unit110, and a charging relay116as a configuration for electrically charging power storage device100with power received from external power supply500. Note that external power supply500is representatively configured by a commercial power grid of single-phase ac. However, the commercial power grid may be replaced with or cooperate with a solar battery panel provided on a roof of a residence or the like to generate power to supply power of external power supply.

To inlet112is connected a charging connector212of charging cable214. Then from external power supply500power is transmitted via charging cable214to vehicle10.

charging unit110is a device receiving power from external power supply500for electrically charging power storage device100. Charging unit110is provided between inlet112and power storage device100. Charging unit110follows a control instruction PWD1received from ECU130to convert ac power that is received from external power supply500via charging cable214and inlet112into dc power for electrically charging power storage device100.

Between charging unit110and power storage device100is provided charging relay116connected such that it is inserted to power lines PL3and NL3. Charging relay116is turned on and off in response to a relay control signal SE1issued from ECU130. Charging relay116is used as a representative example of a switch device which can interrupt a path used to electrically charge power storage device100. That is, any form of switch device is applicable in place of charging relay116.

When power storage device100is electrically charged via external power supply500, ECU130generates control instruction PWD1for controlling charging unit110and outputs the generated control instruction PWD1to charging unit110. At the time, ECU130operates in response to a pilot signal received from a charging circuit interrupting device (not shown) provided at an electric wire section of charging cable214for switching between supplying and interrupting power received from external power supply500to determine the type of external power supply500and control charging unit110in accordance with the type of external power supply500determined.

Furthermore, vehicle10further includes an inlet122provided in the body of vehicle10, a power feeding unit120, and a power feeding relay126as a configuration for supplying power to load device400(seeFIG. 1) external to the vehicle.

To inlet122is connected a power feeding connector222of power feeding cable224. Then, power discharged from power storage device100and/or that generated from driving force output device135(or motor generator160) are/is transmitted to load device400via power feeding cable224. In other words, power storage device100and/or driving force output device135(or motor generator160) correspond(s) to a “power generation unit” provided for generating power supplied external to the vehicle.

Power feeding unit120is a device receiving power discharged from power storage device100and/or that generated from driving force output device135for feeding the received power to load device400external to the vehicle. Power feeding unit120operates in response to a control instruction PWD2received from ECU130to receive via power lines PL3and NL3the power discharged from power storage device100and/or that generated from driving force output device135, which are both de power, and convert the received power to ac power for driving load device400external to the vehicle.

Between power feeding unit120and power storage device100is provided power feeding relay126connected such that it is inserted to power lines PL3and NL3. Power feeding relay126is turned on and off in response to a relay control signal SE2issued from ECU130. Power feeding relay126is used as a representative example of a switch device which can interrupt an electrically discharging path provided from power storage device100and/or driving force output device135. That is, any form of switch device is applicable in place of power feeding relay126.

Although not shown inFIG. 1orFIG. 2, ECU130includes a central processing unit (CPU), a storage device, and an input/output buffer, and receives a signal from each sensor and outputs a control signal to each device, and also controls vehicle10and each device. Note that such control may not be processed by software, and may be processed by dedicated hardware (or electronic circuitry).

ECU130receives the battery data (indicating the battery voltage and the battery current) from monitoring unit105and therefrom calculates the state of charge (SOC) of power storage device100. An SOC indicates a currently available capacity relative to a full charge capacity in percentages (0-100%). How the SOC of power storage device100is calculated can be done in any known manner and accordingly, will not be described in detail.

ECU130generates and outputs a control instruction for controlling PCU150, charging unit110, charging relay116, power feeding unit120, and power feeding relay126.

ECU130communicates via communication unit140via a wire or wirelessly with communication units240and350provided to charging stand200and HEMS300, respectively, external to the vehicle. Then, ECU130receives information from communication units240,350of charging stand200and HEMS300and stores the information to storage unit145.

Note that vehicle10, charging stand200, and HEMS300can communicate via power line communication (PLC), In that case, communication units140,240,350are each configured of a PLC unit, and transmit information via a power line.

The present invention in the embodiment thus provides vehicle10configured to be capable of electrically charging in-vehicle power storage device100by external power supply500and also supplying power therefrom to load device400external to vehicle10. In the following description, electrically charging power storage device100by external power supply500will also be referred to as “external charging”, and supplying outside the vehicle the power discharged from power storage device100and/or the power generated by driving force output device135(or motor generator160) will also be referred to as “external power feeding”.

Note that in the present embodiment the external charging is not essential, and a vehicle traveling only on force provided from the engine to drive the vehicle may not be provided with a configuration allowing the external charging.

Furthermore, theFIGS. 1 and 2configuration may be replaced with a configuration which allows an external power supply and a vehicle that are out of physical contact to be electromagnetically coupled together to supply power, specifically, the external power supply may be provided with a primary coil and the vehicle may be provided with a secondary coil, and the mutual inductance between the primary coil and the secondary coil may be utilized to supply power.

With reference again toFIG. 1, charging stand200includes charging cable214, charging connector212, and a relay210for the external charging. Furthermore, charging stand200includes power feeding cable224, power feeding connector222, and a relay220for the external power feeding. Charging stand200further includes a controller230and communication unit240. Charging stand200is electrically connected to switchboard510provided in a building such as premises600.

charging cable214has one end connected to relay210and the other end connected to charging connector212. Power feeding cable224has one end connected to relay220and the other end connected to power feeding connector222. Charging cable214and power feeding cable224may be separatable from charging stand200. Alternatively, a charging cable and a power feeding cable that are provided to vehicle10may be used to connect charging stand200and vehicle10together.

Furthermore, whileFIG. 1shows charging cable and connector214and212and power feeding cable and connector224and222provided discretely, alternatively a single cable and a single connector may be switched between charging and power feeding and thus used. In that case, vehicle10also has inlets112and122provided as a single inlet switchable between charging and power feeding.

For the external charging, charging connector212is connected to vehicle10at inlet112and relay210is closed, and vehicle10thus receives power from external power supply500through premises600via switchboard510. In contrast, for the external power feeding, power feeding connector222is connected to vehicle10at inlet122and relay220is closed, and vehicle10thus supplies premises600with power. Relays210,220are opened/closed as controlled by controller230.

Controller230is implemented for example as a CPU. Controller230is configured to be capable of communicating with the vehicle10ECU130via communication units240,140wirelessly or via a wire. Controller230is configured to be capable of communicating with the HEMS300CPU340via communication units240,350wirelessly or via a wire.

Controller230transmits a signal indicative of a state of relays210and220(i.e., whether the relays are opened/closed) to the HEMS300CPU340and the vehicle10ECU130. In other words, controller230transmits to CPU340and ECU130a signal indicating which of the external charging and the external power feeding has been selected.

AC/DC converter320receives ac power from charging stand200and converts it into dc power. DC/AC converter310receives the dc power from AC/DC converter320and converts it into ac power. AC/DC converter320and DC/AC converter310are controlled in accordance with a control signal which CPU340generates based on a signal transmitted from the charging stand200communication unit240and indicating which of the external charging and the external power feeding has been selected,

Load device400is any electrical appliance receiving power from external power supply500via switchboard510for operation. Load device400may be premises600or may be individual electric appliances, for example. Alternatively, load device400may be a vehicle other than vehicle10.

Herein, in theFIG. 1power supply system, if external power supply500has failed, the power supplied to load device400is interrupted. Thus, once external power supply500has failed, then, in place of external power supply500, vehicle10is regarded as a power supply source, and from vehicle10power is supplied to load device400. In the following description, a mode allowing vehicle10to be used as a backup power supply for external power supply500to perform the external power feeding will be referred to as an “emergency power generation mode”. In contrast, a mode which allowing the external power feeding and the external charging when external power supply500normally operates will be referred to as a “normal mode”.

In the emergency power generation mode, the power feeder or vehicle10is required to generate ac power of a specification that matches that of the power recipient or load device400. The specification of load device400(hereinafter also referred to as a “load specification”) is a specification for power supplied to load device400and it includes and the frequency and voltage of external power supply500. As an example, if external power supply500is a commercial power grid, the commercial power grid normally has a frequency of 50 kHz or 60 kHz. Furthermore, the commercial power grid generates a commercial ac voltage of 100 V or 200 V.

In the normal mode, the vehicle10ECU130can communicate with HEMS300and charging stand200via communication units140,240,350to obtain the load specification. Then, vehicle10can generate appropriate ac power corresponding to the obtained load specification and supply load device400therewith.

In contrast, once external power supply500has failed, the above described communication function will not normally operate, and the vehicle10ECU130can no longer obtain the load specification. Thus, vehicle10cannot generate ac power of an appropriate frequency and voltage corresponding to load device400and supply load device400therewith. Hereinafter, what problem will arise once external power supply500has failed will be described with reference toFIG. 3.

FIG. 3shows the power supply system when external power supply500has failed.

With reference toFIG. 3, a load specification, or external power supply500's frequency and voltage, is set as a power generation parameter by the HEMS300CPU340. The power generation parameter is transmitted to the vehicle10ECU130via communication units350,240,140, and used by ECU130for a power feeding operation in vehicle10. Specifically, the vehicle10ECU130converts the power that is discharged from power storage device100into the ac power defined by the power generation parameter and supplies it external to the vehicle. Furthermore, ECU130converts the dc power that is generated by driving force output device135into the ac power defined by the power generation parameter and supplies it external to the vehicle.

However, once external power supply500has failed, then, as shown inFIG. 3, the power supplied to HEMS300and charging stand200is interrupted, and communication unit350of HEMS300and communication unit240of charging stand200stop their operations. Thus the power generation parameter cannot be transmitted from HEMS300or charging stand200to vehicle10.

In vehicle10, in contrast, once that external power supply500has failed has been detected, ECU130turns off the normal mode and turns on the emergency power generation mode. Once the emergency power generation mode has been turned on, ECU130controls a power conversion operation in power feeding unit120to convert the dc power that is output from power storage device100and/or driving force output device135into the ac power suitable for driving load device400external to the vehicle. However, as described above, ECU130cannot obtain the power generation parameter for defining the ac power's frequency and voltage, and hence cannot control power feeding unit120.

In order to resolve such a disadvantage, the present embodiment provides a power supply system such that when external power supply500normally operates, i.e., in the normal mode, a specification of power supplied to load device400(or a load specification) is previously obtained and stored to storage unit145as a power generation parameter. Then, once external power supply500has failed and the emergency power generation mode is turned on, vehicle10reads the power generation parameter stored in storage unit145and uses the read power generation parameter to control a power conversion operation of power feeding unit120.

FIG. 4illustrates how the power supply system in the embodiment of the present invention operates in the normal mode.

With reference toFIG. 4, a load specification, or external power supply500's frequency and voltage, is set as a power generation parameter by the HEMS300CPU340. Then, when charging connector212is connected to vehicle10at inlet112or power feeding connector222is connected to vehicle10at inlet122to connect charging stand200and vehicle10together, CPU340transmits the power generation parameter to vehicle10via communication unit350and the charging stand200communication unit240. At the time, CPU340associates the power generation parameter with an identification code ID of charging stand200and thus transmits them.

Vehicle10receives the power generation parameter and the ID of charging stand200via communication unit140, and ECU130associates the received power generation parameter with the ID of charging stand200and thus stores them to storage unit145.

Once external power supply500has failed and the emergency power generation mode is turned on, the vehicle10ECU130uses the ID of charging stand200as a clue to read the power generation parameter from storage unit145. Then, ECU130uses the read power generation parameter to control the power conversion operation in power feeding unit120. This allows vehicle10to output appropriate ac power corresponding to a specification of power supplied to load device400and supply it to load device400via charging stand200and HEMS330.

FIG. 5is a flowchart for illustrating how the vehicle and the charging stand operate in the power supply system in the embodiment of the present invention.

With reference toFIG. 5, Steps S01and S11are performed to connect charging stand200and vehicle10, and in response, Step S12is performed to cause charging stand200to transmit a power generation parameter that is set by the HEMS300CPU340(or a load specification) to vehicle10via communication unit240.

In vehicle10, Step S02is performed to receive the power generation parameter and the ID of charging stand200via communication unit140, and in response, Step S03is performed to cause ECU130to associate the received power generation parameter with the ID of charging stand200and thus store them to storage unit145.

In Steps S04and S13external power supply500fails, and in response, communication unit240of charging stand200stops its operation, and communications between charging stand200and vehicle10are interrupted.

Once external power supply500has failed, then in vehicle10step S05is performed to cause ECU130to determine whether the emergency power generation mode has been turned on. If not (NO in Step S05), the control returns to Step505. If the emergency power generation mode is turned on (YES in Step S05), ECU130proceeds to Step S06to read the power generation parameter in storage unit145by using the ID of charging stand200as a clue. ECU130then proceeds to Step5.07to control the power conversion operation of power feeding unit120with the read power generation parameter to generate ac power to be supplied to load device400from vehicle10.

The ac power generated by vehicle10is supplied to load device400via charging stand200and HEMS300. Thus, once external power supply500has failed, load device400receives power supplied from vehicle10, rather than external power supply500, and is thus driven thereby.

In the present embodiment, power storage device100and driving force output device135(or motor generator160) correspond to a “power generation unit”, power feeding unit120corresponds to a “power feeding unit”, and ECU130corresponds to a “control device”. Furthermore, HEMS300and charging stand200correspond to a “power feeding device”.

As has been described above, the present invention in an embodiment can provide a power supply system such that when an external power supply normally operates, a specification of power supplied to a load device external to a vehicle (or a load specification) can be stored in the vehicle's storage unit, and once the external power supply has failed, the specification stored in the storage unit can be used to supply appropriate power that corresponds to the load specification from the vehicle. This ensures that once the external power supply has failed, backup power is generated to drive the load device stably.

Note that whileFIG. 1andFIG. 2show charging unit110and power feeding unit120as discrete devices, a single power conversion unit may alternatively be provided to be capable of bidirectional power conversion of charging power and feeding power.

Furthermore, whileFIG. 1shows charging stand200and HEMS300each provided with a communication unit by way of example, alternatively, any one of charging stand200and HEMS300may be provided with a communication unit for communicating with vehicle10.

Exemplary Variation

In the above embodiment, a load specification is stored in vehicle10at storage unit145as the load specification is transmitted to vehicle10from charging stand200when external power supply500normally operates.

It is difficult to apply the above configuration, however, when one of charging stand200and vehicle10does not have a communication unit.

Accordingly, in the present variation, when vehicle10is supplied with power from external power supply500, i.e., in the external charging, a load specification is calculated at vehicle10and stored to storage unit145.FIG. 6illustrates how the power supply system in the embodiment of the present invention in the exemplary variation operates in the normal mode.

With reference toFIG. 6, the power supply system in the present variation differs from that shown inFIG. 1in that vehicle10further includes a frequency sensor190and a voltage sensor192.

Frequency sensor190is connected to a power line that connects inlet112and charging unit110together, inserted thereto. Frequency sensor190senses a frequency f of ac power supplied to the power line through inlet112from charging cable214, and outputs the sensed value to ECU130. Voltage sensor192is connected to a power line, inserted thereto, and senses voltage VAC of ac power supplied to the power line and outputs the sensed value to ECU130.

Once charging stand200and vehicle10have been connected via charging cable214and the external charging has thus started, ECU130obtains the values that are sensed by frequency sensor190and voltage sensor192while the external charging is performed. Furthermore, ECU130obtains a supplied current IAC that flows through charging unit110, which corresponds to a current charged to power storage device100. Then, ECU130calculates a load specification, or a frequency and voltage of external power supply500, from the supplied power's frequency f, voltage VAC, and supplied current IAC as obtained.

Specifically, ECU130uses frequency f that is sensed by frequency sensor190as frequency f of external power supply500. Furthermore, ECU130applies voltage VAC sensed by voltage sensor192, supplied current IAC, and a wiring resistance R between vehicle10and switchboard510to an expression (1) to calculate voltage V of external power supply500.

Note that, in expression (1), wiring resistance R is previously calculated from the length of an electric wire of the power line (including charging cable214) provided between vehicle10and switchboard510.

ECU130stores the calculated frequency f and voltage V of external power supply500as a power generation parameter to storage unit145. Then, once external power supply500has failed and the emergency power generation mode is turned on, ECU130reads the power generation parameter from storage unit145and uses the read power generation parameter to control a power conversion operation in power feeding unit120. This allows vehicle10to output appropriate ac power corresponding to a specification of load device400and supply it to load device400via charging stand200and HEMS300.

FIG. 7is a flowchart for illustrating how the vehicle and the charging stand operate in the power supply system in the embodiment of the present invention in the exemplary variation.

With reference toFIG. 7, Steps S21and S31are performed to connect charging stand200and vehicle10via charging cable214, and in response, Step S32is performed to cause charging stand200to supply power from external power supply500to vehicle10.

In vehicle10, Step S22is performed; more specifically, when charging unit110receives power from external power supply500, charging unit110converts the received power into power suitable for electrically charging power storage device100:

The vehicle10ECU130proceeds to Step S23to obtain frequency f and voltage VAC of the power that is supplied by external power supply500from frequency sensor190and voltage sensor192, respectively. Furthermore, ECU130obtains a charging current IAC. The vehicle10ECU130then proceeds to Step S24to calculate frequency f and voltage V of external power supply500(or a load specification). ECU130sets the calculated frequency f and voltage V of external power supply500as a power generation parameter and proceeds to Step S25to store the power generation parameter to storage unit145.

In Steps S26and S34external power supply500fails, and in response, communication unit240of charging stand200stops its operation, and communications between charging stand200and vehicle10are interrupted.

Once external power supply500has failed, then in vehicle10step S27is performed to cause ECU130to determine whether the emergency power generation mode has been turned on. If not (NO in Step S27), the control returns to Step S27. If the emergency power generation mode is turned on (YES in Step S27), ECU130proceeds to Step S28to read the power generation parameter in storage unit145by using the ID of charging stand200as a clue. ECU130then proceeds to Step S29to control the power conversion operation of power feeding unit120with the read power generation parameter to generate ac power to be supplied to load device400from vehicle10.

The ac power generated by vehicle10is supplied to load device400via charging stand200and HEMS300. Load device400receives the power supplied from vehicle10and is thus driven thereby.

As has been described above, the present invention in the exemplary variation can provide the power supply system such that while the external charging is performed the vehicle's ECU calculates a load specification based on power supplied from an external power supply and stores the calculated load specification to a storage unit internal to the vehicle as a power generation parameter. If the vehicle does not have a function to communicate with the charging stand or the HEMS, it can obtain the load specification, and once the external power supply has failed, the specification stored in the storage unit can be used to supply appropriate power that corresponds to the load specification from the vehicle. This ensures that when the external power supply has failed, backup power is generated to drive the load device stably.

INDUSTRIAL APPLICABILITY

The present invention is applicable to power supply systems which supply power from a vehicle to a load external to the vehicle.

REFERENCE SIGNS LIST