Hybrid Electric Vehicle (HEV) and Electric Vehicle (EV) Terminology 1

ABBREVIATIONS AND ACRONYMS

The following acronyms are commonly used in relation to hybrid and EV terminology:

• A — Ampere
• AC — Alternating Current
• ACD — Automatic Connecting Device
• APU — Auxiliary Power Unit
• BAS — Belted-Alternator Starter
• BEV — Battery Electric Vehicle
• BMS — Battery Management System
• CAN — Controller Area Network Data Bus
• CCS — Combined Charging System
• CFR — Code of Federal Regulations
• CP — Control Pilot
• CVT — Continuously-Variable Transmission
• DER — Distributed Energy Resource
• DC — Direct Current
• DCFC — DC Fast Charger
• DWPT — Dynamic Wireless Power Transfer
• ECP — Electrical Connection Point
• EMC — Electromagnetic Compatibility
• EMF — Electromagnetic Field
• EMI — Electromagnetic Interference
• EMS — Energy Management System
• EPS — Electric Power System
• ESD — Electrostatic Discharge
• EV — Electric Vehicle
• EVCC — Electric Vehicle Communication Controller
• EVSE — Electric Vehicle Supply Equipment
• FCEV — Fuel-Cell Electric Vehicle
• FLA — Four-Letter Acronym
• GA — Ground Assembly (WPT)
• HAN — Home Area Network
• HEV — Hybrid Electric Vehicle
• HPU — Hybrid Power Unit
• IMN — Impedance Matching Network
• ISC — Infrastructure-Side Connection
• kW — Kilowatt
• kW∙h — Kilowatt-Hour
• LAN — Local Area Network
• LIN — Local Interconnect Network
• NRTL — Nationally Recognized Testing Laboratory
• OBC — On-Board Charger
• PEV — Plug-in Electric Vehicle
• PHEV — Plug-in Hybrid Electric Vehicle
• RESS — Rechargeable Energy Storage System
• SECC — Supply Equipment Communication Controller
• SEP — Smart Energy Profile
• SGIP — Smart Grid Interoperability Panel
• SOC — State of Charge
• SOH — State of Health
• TLA — Three-Letter Acronym
• UBE — Usable Battery Energy
• V — Volt
• V2G — Vehicle-to-Grid
• V2G-AC — Vehicle-to-Grid via Alternating Current
• V2G-DC — Vehicle-to-Grid via Direct Current
• V2H — Vehicle-to-Home
• V2I — Vehicle-to-Infrastructure
• V2L — Vehicle-to-Load
• V2V — Vehicle-to-Vehicle
• V-A — Volt-Ampere
• VA — Vehicle Assembly (WPT)
• VGI — Vehicle/Grid Integration
• VIN — Vehicle Identification Number
• VM — Vehicle Manufacturer
• VSC — Vehicle-Side Connection
• VRef — Reference Voltage
• VRefOfs — Reference Voltage Offset
• W — Watt
• WCS — Wireless Charging System
• WPT — Wireless Power Transfer
• xEV — “Any” Electrified Vehicle

HYBRID ELECTRIC (HEV) AND ELECTRIC VEHICLE (EV) TERMINOLOGY

AC (ALTERNATING CURRENT) CHARGING

The process of supplying electrical energy to the vehicle via an alternating current (AC) (sinusoidal, varing equidistant across the 0 A axis) which is then converted to direct current (DC) for charging an RESS and possibly supplying other vehicle demands.

ADEQUATE VENTILATION

As defined in NFPA 30 and NFPA 70, ventilation is adequate if it is sufficient to prevent accumulation of hydrogen vapor-air mixtures in concentrations over one-fourth of the lower flammability limit.

AIR CLEARANCE

The shortest distance through air between two conductive parts.

ALL ELECTRIC RANGE

The distance an electrified vehicle can travel without using any fuel (gas, diesel, natural gas, etc.) for propulsion or for performing any other functions of the vehicle. Note that the all-electric range must be accompanied with a reference to the drive cycle used to determine the range.

AUTOMATIC CONNECTION DEVICE (ACD)

A system that establishes without direct human intervention a conductive electrical interface between on-vehicle and off-vehicle components for the purpose of power transfer.

AUTOMATIC TRANSMISSION

A transmission in which ratio changes are effected automatically without requiring manual assist.

AUXILIARY POWER UNIT (APU)

A device used to gererate propulsion power but without a direct mechanical connection to the drive wheels. Some examples of auxiliary power units are internal combustion engines connected solely to an electric generator, an engine connected solely to a hydraulic pump, or fuel cells.

BATTERY ELECTRIC VEHICLE (BEV)

A vehicle that receives its on-board propulsion power solely from batteries, unlike a hybrid vehicle that may receive a portion of its power from a separately fueled power source, such as an internal combustion engine.

BI-DIRECTIONAL INVERTER

A device that can convert from AC to DC in one direction to serve as a battery charger, and then be capable of being reversed and convert DC to AC in the other direction to serve as an inverter. This term is generally not used if the inverter is also capable of injecting or absorbing reactive power while charging or discharging.

BREAKDOWN

The failure of the dielectric of an insulation due to the effects of an excessive electric field and/or physical or chemical deterioration of the dielectric material.

CHARGE CONNECTOR

A conductive or inductive device that establishes an electrical connection to the electric vehicle for the purpose of charging and information exchange.

CHARGE DEPLETING (CD) MODE

An operating mode of an HEV in which the vehicle runs by consuming only electric energy from the RESS charged from an external power source, or along with the fuel energy, simultaneously or sequentially, until the charge-sustaining (CS) mode state is obtained.

CHARGER

A functional component that can be located on or off the vehicle that supplies electrical power at the correct voltage and current levels for battery charging.

CHARGE SUSTAINING (CS) MODE

An operating mode where the HEV runs by consuming fuel energy while sustaining the electric energy of the RESS.

CHARGING LEVEL

A term used to bracket the maximum amount of allowable current or power that can be transferred between off-vehicle and on-vehicle components during RESS charging or reverse power flow (RPF). Power breakpoints for the different level brackets are defined in the individual SAE documents defining the specific charge technology (e.g., SAE J1772, SAE J2954).

CHASSIS GROUND

The conductor used to connect the non-current-carrying metal parts of the vehicle high voltage system to the vehicle ground system.

COMBINED CHARGING SYSTEM (CCS)

A conductive charge method defined by SAE J1772 and other international standards supporting both AC and DC power transfer using a common communication interface and a harmonized set of electrical/physical interfaces.

CONDUCTIVE

Having the ability to transmit electricity through a physical path (conductor).

CONNECTION CYCLES

Refers to connect and disconnect cycles of connectors. One insertion and withdrawal operation is a connection cycle.

CONNECTOR

A component which terminates conductors for the purpose of providing connection and disconnection to a suitable mating component. For the purposes of charging an electric vehicle, this component creates a coupling from the EVSE to the vehicle, to transfer energy and to exchange information.

CONTACT

The part of a switch, relay, or connector that carries current.

CONTACT FORCE

The force which two contacts exert against each other in the closed position under specified conditions. The typical units are Newtons (N).

CONTACT RESISTANCE

The electrical resistance of a single mated set of contacts under specified conditions. The typical units are ohms (Ω).

CONTROL PILOT

An electrical signal sourced by the electric vehicle supply equipment (EVSE). It performs several functions, including assuring that the vehicle is present and connected, permits energizing/de-energizing of the supply, transmits the supply equipment current rating to the vehicle, monitors the presence of the equipment ground, and establishes vehicle ventilation requirements. Refer to SAE J1772 for a complete description.

COOPERATIVE REGENERATIVE BRAKING

Maximizes energy recovery by actively controlling the friction braking in coordination with the regenerative braking system.

COUPLER

A device connected to the electric vehicle supply equipment that transfers power to the electric vehicle for charging the energy storage system and permits the exchange of information between the electric vehicle and the electric vehicle’s supply equipment. Informational note: Per SAE J3085, this term has another definition related to the connection of a hitch-ball for trailering. Contextual clues in actual usage of the term should make the meaning clear to the reader.

DC (DIRECT CURRENT) CHARGING

The process of supplying electrical energy to the vehicle via a direct current supply (constant, positive voltage) for direct charging of the RESS. This type of charging is accomplished with a charger located off-board from the vehicle.

DISTRIBUTED ENERGY RESOURCE (DER)

A power generation, energy storage or load device which functions to provide electric capacity or energy where it is needed on the distribution grid, or one that can be controlled as a load. For the purposes of using an electric vehicle battery as a DER, such units react to variable demand from a grid operator.

DER MANAGING ENTITY (DME)

An entity that monitors and manages the DER through the local DER communication interface and could be, for example, a utility company, an energy aggregator, a building energy management system, etc.

DRIVING PROFILE

A vehicle speed-versus-time schedule that is used to test vehicle and battery characteristics.

DYNAMIC WIRELESS POWER TRANSFER (D-WPT)

A wireless power transfer function which transmits power from a ground assembly to a vehicle assembly during the time which a vehicle is passing over the transmitting device.

E-TRANSMISSION, E-TRANSAXLE, OR E-AXLE

A device which combines the transmission, transaxle, or axle and the electric drive subsystem.

ELECTRIC MACHINE

An electromechanical device that acts as a motor and/or generator and the electromagnetically active components thereof such as the rotor and stator.

ELECTRIC VEHICLE (EV)

An automotive-type vehicle, intended for public roadway use, for which propulsion is powered by an electric motor that draws primarily from a rechargeable energy storage system (RESS). For the purpose of this document, an automotive-type vehicle is defined as follows, by 40 CFR Part 600, Subchapter Q:

a. Any four-wheeled vehicle propelled by a combustion engine using on-board fuel OR by an electric motor drawing current from a rechargeable storage battery or other portable energy devices. b. Which is manufactured primarily for use on public streets, roads, and highways. c. Which is rated not more than 3855.6 kg (8500 pounds), which has a curb weight of not more than 2721.6 kg (6000 pounds), and which has a basic frontal area of not more than 4.18 m2 (45 ft2).

ELECTRIC POWER SYSTEM (EPS)

Equipment or facilities that deliver electric power to a load, e.g., an electric utility provider that supplies energy to a load such as an electric vehicle.

ELECTRIC VARIABLE TRANSMISSION

A transmission with infinitely variable speed ratios within a defined range by using electric motors/generators to supply a ratio of gradiants between a propulsion drive unit and the transaxle.

ELECTRIC VEHICLE SUPPLY EQUIPMENT (EVSE)

The conductors, including the ungrounded, grounded, and equipment grounding conductors, the electric vehicle connectors, attachment plugs, and all other fittings, devices, power outlets, and other components intended to deliver energy to an electric vehicle.

ENERGY MANAGEMENT SYSTEM (EMS)

A system that can communicate with a plug-in electric vehicle or an EVSE for the purpose of controlling the charging or discharging of the PEV battery.

EQUIPMENT GROUND (GROUNDING CONDUCTOR)

A conductor used to connect the non-current-carrying metal parts of the EV supply equipment to the system grounded conductor, the grounding electrode conductor, or both at the service equipment.

EV/PHEV CHARGING SYSTEM

The equipment required to condition and transfer energy from the constant frequency, constant voltage supply network to the direct current, variable voltage EV traction battery bus for the purpose of charging the battery and/or operating vehicle electrical systems while connected.

EV CONNECTOR

Off-board component used to interface with the vehicle-mounted EV inlet to supply power and provide communication interface.

FEDERAL URBAN DRIVING SCHEDULE (FUDS)

The Environmental Protection Agency (EPA) urban dynamometer driving schedule, as defined in 40 CFR, 86.115-78. A driving profile defined by the EPA to test for vehicle emissions and city fuel economy. This schedule is also referred to as “UDDS” and “LA4.”

FOUR-QUADRANT INVERTER

An electronic device that can produce or absorb both active and reactive power. When a PEV is discharging, the device serves as an inverter converting DC current to AC current. This device can displace the AC current waveform relative to the AC voltage waveform to generate or absorb reactive power, depending on whether it leads or lags the supplied current relative to the grid voltage.

FUEL CELL ELECTRIC VEHICLE (FCEV)

A vehicle that derives some fraction of its propulsion energy from an onboard fuel cell power system.

FUSABLE LINK

A device in an electrical path which interrupts current flow when a maximum power throughput occurs. For purposes of high power electric drive units, a pyrotechnic fusible link may be used which establishes a non-reversable and instantaneous break in the current path.

GROUND ASSEMBLY (GA)

A wireless power transfer assembly on the infrastructure side consisting of a coil, a power/frequency conversion unit and controller, as well as the wiring from the grid and between each unit, filtering circuits, housing(s), etc., necessary to function as the power source of wireless power charging system. The GA includes communication elements necessary for communication between the GA and the vehicle assembly (VA) and any auxiliary systems contained on the infrastructure side of the WPT system. The GA for wireless power transfer is analogous to the term EVSE which is applicable to conductive power transfer systems. Informational note: Some documents published by other standards developing organizations have used the term wireless power transfer equipment (WPTE) to be roughly equivalent to the SAE term ground assembly.

HIGH VOLTAGE

Any vehicle wiring system which contains one or more circuits operating at greater than or equal to 60 VDC or 30 VAC.

HYBRID POWER UNIT (HPU)

A device used to generate propulsion power, some of which can be distributed mechanically to one or more of the drive wheels.

HYBRID TRANSMISSION

A transmission connected to a prime mover (such as ICE) and to other devices such as electric motors/generators, pump motors, or other reversable machines, used as inputs and/or outputs to propel the vehicle.

HYBRID VEHICLE

A vehicle with two or more energy storage systems, both of which must provide propulsion power, either together or independently.

HYBRID ELECTRIC VEHICLE (HEV)

A vehicle that can draw propulsion energy from both of the following sources of stored energy: (1) a consumable fuel, and (2) an RESS that is charged by an electric motor-generator system, an external electric energy source, or both.

HYDRAULIC HYBRID

A hybrid vehicle where hydraulic fluid is used as the coupling between propulsion elements and energy storage.

INDUCTIVE CHARGING SYSTEM

A charging system that transfers power across a two-part transformer and rectifies that power into DC voltage to the batteries (refer to SAE J1773 and SAE J2954).

INSERTION FORCE (N)

The force required to fully insert a set of mating components.

INFRASTRUCTURE-SIDE CONNECTION (ISC)

The connections made for the ACD system on the infrastructure side of the connection. The connection is made when the infrastructure-side connection mates with the vehicle-side connection. The ISC power transfer is analagous to the term “EVSE” which is applicable to conductive power transfer systems.

INTEROPERABILITY CLASS I GA (WPT)

A product GA, as a functional component in a wireless power transfer system, which has been verified to meet the interoperability, performance and safety requirements for an Interoperability Class I GA as described in SAE J2954, 5.4.1.

INTEROPERABILITY CLASS II GA (WPT)

A product GA, as a functional component in a wireless power transfer system, for deployment in a home garage or locations for a captive fleet and not intended to be generally available to the public. It has been verified to meet the interoperability, performance, and safety requirements for an interoperability Class II GA, as described in SAE J2954, 5.4.2.

INVERTER

Power conversion equipment that can take DC current from a PEV battery and provide AC power to the electric power system (EPS), or to premises which have been isolated from the grid, or to an isolated load. Such equipment is also capable of converting energy from the EPS to DC current to charge the battery of a PEV.

LIGHT DUTY (LD) PLUG-IN VEHICLE

A three- or four-wheeled vehicle propelled by an electric motor drawing current from a rechargeable storage battery or other energy devices for use primarily on public streets, roads, and highways, and rated at less than 4545 kg gross vehicle weight (GVW).

NET AMPERE-HOURS

For a discharge test including both negative (discharge) and positive (regen) current or power steps, the difference between the A•h removed from the battery during discharge steps and the A∙h returned to the battery during regen steps, regardless of battery charge acceptance. Typical units are ampere-hour (A∙h).

OFF-VEHICLE CHARGE CAPABLE

The capability of a charging system in which a vehicle with a battery can be charged from an off-vehicle electrical energy source.

OPERATING TEMPERATURE

The temperature range in which a component is designed to operate under normal conditions. Typical units are degrees Celcius (°C).

OVERCURRENT PROTECTION DEVICE

A fuse, circuit breaker, intelligent contactor, or other device placed in an electrical circuit to provide current overload protection.

PLUG-IN ELECTRIC VEHICLE (PEV)

An electric vehicle that can be recharged with an off-board source of electricity; it includes both battery electric vehicles (BEV) and plug-in hybrid electric vehicles (PHEV).

PLUG-IN HYBRID ELECTRIC VEHICLE (PHEV)

A hybrid electric vehicle with an RESS that is designed to be off-vehicle charge capable.

POWER ASSIST

A hybrid mode in which the HPU power output is augmented by energy drawn from the RESS, resulting in total power output that exceeds the HPU rating.

POWER FACTOR

The ratio of active (or real) power in watts to apparent power in volt-amps at the fundamental frequency of power transmission (i.e., 60 Hz). It is a measure of the phase shift that occurs between line voltage and line current when the AC line is loaded with a linear load having reactive characteristics.

POWER-SPLIT TRANSMISSION

A transmission providing continuously variable torque/speed ratios by the use of differential gearing connected with at least one electric motor-generator.

POWERTRAIN

All components that are at least intermittently connected to one of more of the vehicle’s wheels. For purposes of an electrified powertrain, such components include the elements of a propulsion system that convert electrical energy to mechanical energy at the wheels of an electric vehicle. It includes all drivetrain components plus an electrical power inverter and/or controller, but not the electrochemical storage system. For a hybrid-electric vehicle, the hybrid power unit is also included.

PRE-CHARGE

A process of limited current supply from a charger to the vehicle battery charging electronics used to bring a low voltage circuit up to the voltage of a higher voltage circuit prior to removing the current limit. The pre-charge process is typically performed to limit the current inrush into a circuit with significant capacitance such as power electronics.

PRODUCT GA (WPT)

An SAE J2954-compliant GA for commercialization, which has been verified to meet both operational and safety requirements defined therein.

PRODUCT VA (WPT)

An SAE J2954-compliant VA assembly that has been developed for series commercialization and has been verified to meet the performance and safety requirements defined therein.

PROPULSION SYSTEM

The combination of the powertrain and energy supply system.

RANGE

The maximum distance that a vehicle can travel without the addition of additional energy in the form of fuel or off-vehicle charging.

RANGE EXTENDER

A small engine-powered generator or auxiliary power unit (APU) added to a battery electric vehicle to produce a plug-in electric vehicle (PEV). This generator sustains vehicle operation beyond the range provided by the batteries alone.

RATED VOLTAGE (V)

Voltage range at which a device is designed to operate.

REGENERATIVE BRAKING

The function of the electrical machine in converting mechanical power inputs to electrical power outputs, ultimately for the purpose of providing energy for storage in the RESS and to provide assisted braking force.

RESS (RECHARGEABLE ENERGY STORAGE SYSTEM)

Any energy storage system that has the capability to be charged and discharged. (Examples: batteries, capacitors, and electro-mechanical flywheels.)

RESS AVAILABLE ENERGY

Energy available at the connection point of the RESS to the system under specified conditions.

RESS DRIVING

Ability to drive the vehicle using only the energy from the RESS.

RESS LAUNCH

Capability to launch the vehicle using only the energy from the RESS.

REVERSIBLE MACHINE

A device that can operate in both mechanical power output mode such as hydraulic motoring or electric motoring, and mechanical power input mode such as hydraulic pumping or electric generating. These can be hydrodynamic, hydrostatic, or electromechanical devices.

REVERSE POWER FLOW (RPF)

The intentional flow of the electrical power from the vehicle to an external device via vehicle components normally used for charging the RESS.

ROTOR

The rotating magnetic or electromagnetic part of the electric machine that is connected to the geartrain to convey mechanical power for motoring and/or generating.

SERIES HYBRID

A hybrid vehicle in which all power is converted to a non-mechanical form prior to conversion back to mechanical power. For example, a vehicle with an APU is a series hybrid because the APU converts all power to electrical power which is then combined with any available battery power and sent to one or more electric motors.

SMART CHARGING

A managed-charging condition in which an EVSE or PEV optimizes the vehicle charging and discharging such that the combination of charging schedule, customer preferences (such as time when the vehicle is expected to be fully charged), cost of energy, and grid capacity are adjusted to meet customer preferences.

SMART GRID

An electricity delivery system that monitors, protects, and automatically optimizes the operation of its interconnected elements.

SPLIT TORQUE DRIVE TRANSMISSION

A transmission which comprises two or more parallel torque paths. The individual paths may be any of several types such as mechanical, hydrodynamic, hydrostatic, or electromechanical.

STAND-ALONE INVERTER

An inverter intended to provide electrical energy to a load not associated with the electric utility or grid. Generally applied only to V2H or V2L situations and not V2G.

START/STOP

Engine is automatically turned off when power demand is zero or negative, such as during vehicle stop, and then restarted automatically. This is sometimes referenced in the industry as a micro hybrid.

STATE OF HEALTH (SOH)

The energy storage capability of the present condition of an RESS compared to that at the beginning of serviecable life of the vehicle.

STATOR

The stationary, current conducting eletromagnetic part of the electric machine that conveys electrical power to and from the rest of the electric drive.

TEST STATION GA (WPT)

The GA used to verify the performance of candidate product VAs. The test station GA is defined in SAE J2954, Appendix C.

TEST STATION VA (WPT)

The VA used to verify the performance of candidate product GAs. The test station VA is defined in SAE J2954, Appendix D.

TRACTION MOTOR

An electric motor which provides variable mechanical output power to the vehicle drivetrain.

TRANSAXLE

A device which combines a transmission with a final drive unit that includes a differential.

TRANSMISSION

A device for transmitting power at a multiplicity of speed and torque ratio.

USABLE BATTERY ENERGY (UBE)

The measure of RESS capacity (in kW∙h) at a given point in time, indicating the remaining electric-mode driving range of an xEV.

VEHICLE ASSEMBLY (VA)

A wireless power transfer assembly on the vehicle side, consisting of a coil, power electronics, control, and communication necessary to receive power from an associated ground assembly (GA).

VEHICLE INLET (CHARGE)

The device on the electric vehicle into which the connector is inserted for the purpose of transferring energy and exchanging information.

VEHICLE-SIDE CONNECTION (VSC)

The connections made for the ACD system on the vehicle side of the connection. The connection is made when the infrastructure-side connection mates with the vehicle-side connection.

VEHICLE-TO-GRID INTEGRATION (VGI)

A form of managed charging in which either charging or discharging is adjusted to meet the prioritized needs of the EV owner and the power utility grid. Term used to describe the connection of PEV vehicles to the electrical grid under coordinated, intelligent control via digital communication to allow overall optimization of both sides of the power flow. This general term includes both V1G and V2G operations.

V1G

A form of managed charging in which the charging (power level and time of charge) is adjusted to meet the prioritized needs of the EV owner and the grid.

V2G

A form of managed charging, where, in addition to adjusting charging behavior (V1G), a vehicle RESS can discharge to the utility grid. The charging time, charging power level, discharge time, and discharge power levels are all manageable in order to meet the prioritized needs of the EV owner and the grid.

WIRELESS CHARGING SYSTEM (WCS)

The system for wireless power transfer used to conduct, through an air gap, energy from the electric supply network to charge the EV RESS.

WIRELESS POWER TRANSFER (WPT)

The transfer of electrical power between the AC supply network and the electric vehicle by contactless means. For purposes of automotive applications, such a WPT function is one that transfers power across an airgap utilizing a two-part transformer (from the ground assembly [GA] to the vehicle assembly [VA]) and then rectifies that power into DC voltage to charge the RESS (refer to SAE J2954).

xEV

Any electrified propulsion vehicle with a high voltage system, including, but not limited to, HEV, PHEV, PEV, BEV, FCEV, and EV.