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Signaling Communication for Wirelessly Charged Electric Vehicles: SAE J2931/6-2022
🛠️ Note: this article focuses on engineering interpretation, not clause-by-clause translation.
The adoption of wireless power transfer for electric vehicles eliminates the need for physical connectors, but it also requires robust communication between the vehicle and charging infrastructure. SAE J2931/6-2022, titled Signaling Communication for Wirelessly Charged Electric Vehicles, addresses this need by establishing requirements for the physical (PHY) and data link (MAC) layer communications between Plug-in Electric Vehicles (PEV) and Electric Vehicle Supply Equipment (EVSE). This Information Report is a key part of the SAE wireless charging standards family, complementing SAE J2954 and SAE J2847/6 by focusing on the underlying communication framework.
Scope and Purpose
SAE J2931/6 defines the communication architecture for wireless charging, ensuring that PEVs and EVSEs can establish a reliable link. The standard specifies that all PHY/MAC requirements should follow ISO 15118-8, which in turn references IEEE 802.11 wireless LAN standards. By delegating detailed specifications to ISO 15118-8, SAE J2931/6 avoids duplication of effort and aligns with international vehicle-to-grid communication protocols.
The purpose of this report is to complement SAE J2954 (wireless power transfer) and SAE J2847/6 (message details) by describing the physical layer communication. It also addresses issues related to PEV association—the process by which a vehicle pairs with a specific charging station—and interoperability across different manufacturers, utilities, and deployment scenarios. These scenarios include home areas, multifamily dwellings, street parking, work sites, and businesses, each with unique communication requirements.
Technical Framework: PHY/MAC Layer Requirements
The communication between a wirelessly charged PEV and a wireless EVSE occurs over one of the IEEE 802.11 PHY layers as described in ISO 15118-8. This design choice ensures that the link uses widely adopted wireless local area network technology, facilitating interoperability and reducing implementation barriers. Both EVSE and EV requirements for PHY/MAC are defined entirely in ISO 15118-8, making SAE J2931/6 a concise reference document that points to the detailed international standard.
| Standard | Focus |
|---|---|
| SAE J2836/6 | Use cases and general information for wireless charging communication |
| SAE J2847/6 | Message details for wireless power transfer communication |
| SAE J2931/6 | Requirements and protocol for physical and data link layers |
The standard also considers integration with Home Area Networks (HAN), which may interface with home appliances and the utility. This requires careful association procedures to ensure the correct PEV is linked to the intended EVSE, especially in environments with multiple vehicles and charging stations.
Design Insight: SAE J2931/6 adopts a modular approach by referencing ISO 15118-8 for all PHY/MAC details. This streamlines the standard and ensures compatibility with international vehicle-to-grid communication specifications. Engineers developing wireless charging systems should focus on implementing ISO 15118-8 requirements and understanding the association scenarios described in J2836/6 and J2847/6.
For engineers working on wireless charging communication, SAE J2931/6 provides a clear roadmap:
- 🔧 Adopt IEEE 802.11 PHY layers as specified in ISO 15118-8 for the wireless link.
- 🔎 Understand association procedures to ensure reliable PEV-EVSE pairing, avoiding interference and security risks.
- ⚠️ Avoid proprietary communication protocols that may hinder interoperability; adhere to the ISO and SAE frameworks.
- Consider the variability in deployment environments (home, work, street) and design the communication system to handle different scenarios.
⚠️ Common Mistake: Neglecting proper association procedures can lead to incorrect PEV-EVSE pairing. Always follow the use cases and message details defined in SAE J2836/6 and SAE J2847/6 to ensure robust communication.
Frequently Asked Questions
What physical layer standards are used for wireless EV charging communication?
SAE J2931/6 references ISO 15118-8, which specifies the use of IEEE 802.11 PHY layers. This ensures that the wireless communication link uses standard Wi-Fi technology adapted for vehicle-to-grid applications.
How is the association between PEV and EVSE established?
Association procedures are described in SAE J2836/6 (use cases) and the actual messages are defined in SAE J2847/6. SAE J2931/6 specifies the PHY/MAC layer requirements that support these higher-layer association protocols.
Why is interoperability important in wireless charging communication?
Interoperability ensures that vehicles and charging stations from different manufacturers can communicate correctly. SAE J2931/6 promotes this by mandating compliance with ISO 15118-8, a widely recognized international standard, and by addressing various deployment scenarios.
What role does the Home Area Network (HAN) play?
The HAN may interface with the EVSE and utility grid, enabling energy management and smart charging. SAE J2931/6 considers these scenarios, ensuring that the communication link can be integrated with home networks and utility interfaces.
By following the guidelines of SAE J2931/6, engineers can develop reliable and interoperable wireless charging systems that meet the needs of diverse charging environments.
