ISO 15118-20: Bidirectional V2G charging and MCS communication standard
ISO 15118-20 is the second generation V2G communication standard of the ISO 15118 series. It supports bidirectional charging (V2G/V2H/V2L), Megawatt Charging System (MCS), wireless charging and more flexible energy scheduling negotiation. It is backward compatible with the ISO 15118-2 PnC process.
Summary
ISO 15118-20 is the second generation standard of ISO 15118 V2G communication series (replacing some functions of ISO 15118-2). It supports two-way charging (V2G / V2H / V2L), Megawatt Charging System (MCS), wireless charging (WPT), and provides more flexible dynamic energy scheduling. (Dynamic Mode) with updated PnC security mechanisms.KopherBit EVCC provides ISO 15118-20 EV side stacking, covering core functions such as DC bidirectional, PnC, TLS 1.3, etc.
Technical Role
ISO 15118-20 redesigns the message set on the V2G application layer. Compared with ISO 15118-2, it mainly adds:
- Bidirectional Energy Flow: Define the BPT (Bidirectional Power Transfer) process, and the vehicle can become an energy storage unit to supply power to homes, power grids, or other equipment.
- Dynamic Mode: Allows dynamic adjustment of energy schedule during the charging process to match grid demand (Demand Response) or fluctuations in renewable energy production.
- MCS (Megawatt Charging System): Planning MW-level charging communication foundation for commercial vehicles (trucks, buses).
- WPT (Wireless Power Transfer): Added wireless charging alignment and pairing process.
- TLS 1.3 with newer cipher suites: Replaces ISO 15118-2 part of the legacy cipher.
- Independent Service Architecture: Modularize SDP, TLS, EXI, and PnC processes and coexist in the same stack with ISO 15118-2.
ISO 15118-20 and ISO 15118-2 can coexist on the same PLC connection; EVCC is dynamically switched during the ServiceDiscovery stage according to the supported version announced by SECC.
Architecture
| Subsystem | Role |
|---|---|
| HomePlug Green PHY | PLC physical layer, follows ISO 15118-3. |
| IPv6 / DHCP / SDP | Get SECC endpoint. |
| TCP/TLS 1.3 | Force the use of TLS 1.3 with updated cipher suites. |
| V2G TP / EXI | Message serialization and efficient encoding. |
| State Machine | ISO 15118-20 Bidirectional / Dynamic / MCS / WPT state machine. |
| PKI | Updated credential chaining and OEM CA / Contract CA processes. |
| BPT Logic | Bidirectional energy flow logic, interfaced with vehicle BMS and Inverter. |
| Energy Scheduling | Dynamic Mode scheduling negotiation, interface with the vehicle energy management system (EMS). |
Key Capabilities
- Two-way charging (V2G / V2H / V2L): The car acts as an energy storage and can send energy back to the grid or home.
- Dynamic Mode: Dynamically adjust charging power and time period according to power grid signals.
- MCS Support: Prepare for MW-level charging of large commercial vehicles.
- WPT (Wireless Charging): Integration of alignment and pairing processes.
- TLS 1.3 Encryption: updated security standard, compatible with modern PKI.
- Coexists with ISO 15118-2: The same EVCC stack can support two generations of protocols at the same time, switching according to EVSE.
Engineering Inputs Required
| Input | Purpose |
|---|---|
| Two-way demand | Whether V2G / V2H / V2L, target applications (home energy storage, grid support, etc.) are required. |
| Inverter / Bidirectional OBC Specification | Bidirectional energy flow requires reversible power conversion hardware support. |
| Vehicle EMS signal | Dynamic Mode The lower end needs to provide energy demand prediction, remaining time, SoC target, etc. |
| BMS specifications | Upper and lower charge and discharge limits, cycle life limits, and discharge permit conditions. |
| PKI settings | TLS 1.3 corresponding OEM CA, Contract CA, Trust Anchors. |
| Applicable markets | MCS/WPT regulations and communication band differences. |
How KopherBit Supports This
- EVCC Software Stacking: KopherV2G provides ISO 15118-20 BPT, Dynamic Mode, PnC TLS 1.3 complete stacking.
- Integration with ISO 15118-2: The same EVCC supports two generations of standards at the same time, eliminating the need to develop two sets of stacks.
- PKI integration: Assist OEMs in planning the credential chain and OCSP process corresponding to ISO 15118-20.
- Verification: KCU Gen2 Testbench provides bidirectional process and Dynamic Mode message tracking capabilities.
FAQ
Does ISO 15118-20 replace ISO 15118-2?
Not quite.ISO 15118-20 redesigns the message set and expands functionality, but ISO 15118-2 will still be used in a large number of existing unidirectional DC/AC charging scenarios for some time.EVCC usually supports two generations at the same time to cover all charging piles.
Does bidirectional charging require new hardware?
need.The EV side must have a reversible power converter (bidirectional OBC or reversible DC/DC), and the BMS must support discharge mode and have a battery life management strategy.EVCC Software support is sufficient, but hardware is indispensable.
What applications is Dynamic Mode suitable for?
Grid demand response (Demand Response), solar/wind energy ratio optimization, home energy storage to match electricity price periods.Dynamic Mode allows EVSE to continuously update the energy schedule during charging, and EVCC is adjusted in conjunction with the vehicle EMS.
Is TLS 1.3 mandatory?
ISO 15118-20 forces TLS 1.3 with compatible cipher suites, unlike ISO 15118-2 (TLS 1.2/1.3).OEM PKI must be planned accordingly.
How does MCS relate to existing CCS charging?
MCS mainly serves commercial vehicles (trucks, buses), targeting MW-level power and larger connectors.ISO 15118-20 is the basis for its communication, but MCS still relies on additional hardware standards (CharIN MCS).
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