Glossary
Quick reference for EV charging terminology.
- AFIR
- Alternative Fuels Infrastructure Regulation. EU regulation mandating minimum charging infrastructure along major corridors.
- BMS
- Battery Management System. Controls cell balancing, monitors state of charge, and communicates battery limits to the charger.
- CCS
- Combined Charging System. DC fast charging connector standard using PLC communication over the control pilot line.
- CHAdeMO
- DC fast charging standard using CAN bus communication. Declining in favor of CCS/NACS.
- CharIN
- Charging Interface Initiative. Industry association promoting CCS, organizing Testivals, and driving ISO 15118 adoption.
- Control Pilot
- PWM signal on the CP line between charger and vehicle, defined by IEC 61851. Communicates max current and connection state.
- CPO
- Charge Point Operator. Company that owns, installs, and maintains charging stations.
- CSMS
- Charging Station Management System. Backend software that manages chargers remotely via OCPP.
- DIN 70121
- DIN SPEC 70121. Early DC charging communication protocol, predecessor to ISO 15118. Still used by most CCS sessions.
- Eichrecht
- German calibration law requiring transparent, verifiable energy metering at public chargers.
- eMSP
- e-Mobility Service Provider. Issues charging cards/apps to drivers and handles billing.
- EVSE
- Electric Vehicle Supply Equipment. The complete charging unit including connectors, electronics, and housing.
- EXI
- Efficient XML Interchange. Binary encoding for XML used by ISO 15118 and DIN 70121 to compress V2G messages.
- HMI
- Human-Machine Interface. The charger's screen, LEDs, and user-facing controls.
- Hubject
- eRoaming platform operating the OICP protocol and PKI infrastructure for Plug & Charge.
- IEC 61851
- International standard for EV conductive charging systems. Defines control pilot signal, states, and safety requirements.
- IMD
- Insulation Monitoring Device. Continuously checks DC line insulation resistance to detect ground faults.
- ISO 15118
- International standard for vehicle-to-grid communication. Enables Plug & Charge, TLS, and bidirectional power transfer.
- MID
- Measuring Instruments Directive. EU directive for metering accuracy at public chargers.
- NACS
- North American Charging Standard (SAE J3400). Originally Tesla's connector, now adopted as the North American standard.
- NEVI
- National Electric Vehicle Infrastructure. $5B US federal program funding EV charging along highway corridors.
- NMK
- Network Membership Key. Encryption key exchanged during SLAC to create a private PLC network between charger and vehicle.
- OCPI
- Open Charge Point Interface. Protocol for CPO-eMSP communication, enabling roaming and data exchange.
- OCPP
- Open Charge Point Protocol. Communication standard between chargers and backend systems (CSMS). Versions: 1.6, 2.0.1, 2.1.
- OCTT
- Open Charge Point Test Tool. OCA's official conformance testing tool for OCPP certification.
- OICP
- Open InterCharge Protocol. Hubject's centralized roaming protocol connecting CPOs and eMSPs.
- PFC
- Power Factor Correction. First conversion stage in a DC charger, converts AC to a stable DC bus voltage.
- PKI
- Public Key Infrastructure. Certificate hierarchy used for Plug & Charge authentication (V2G Root CA, OEM, MO certificates).
- PLC
- Powerline Communication. High-frequency data signals sent over the control pilot line using HomePlug Green PHY.
- Plug & Charge
- ISO 15118 feature enabling automatic authentication via certificate exchange when the cable is plugged in. No card or app needed.
- Pre-charge
- Process where the charger matches its output voltage to the battery voltage before closing DC contactors.
- PWM
- Pulse Width Modulation. The control pilot uses PWM duty cycle to communicate maximum allowed current to the vehicle.
- SLAC
- Signal Level Attenuation Characterization. Pairing process that matches a vehicle to the correct charger via PLC signal strength measurement.
- SOC
- State of Charge. The battery's current energy level as a percentage of full capacity.
- TLS
- Transport Layer Security. Encryption protocol used to secure OCPP WebSocket connections and ISO 15118 V2G communication.
- Type 2
- IEC 62196-2 connector standard used for AC charging in Europe. Also forms the top half of the CCS Combo 2 connector.
- V2G
- Vehicle-to-Grid. Bidirectional power flow where the EV battery exports energy back to the grid.
- V2X
- Vehicle-to-Everything. Umbrella term for V2G, V2H (home), V2B (building), and V2L (load).
- WebSocket
- Persistent bidirectional TCP connection used by OCPP for communication between charger and CSMS.