Energy Transfer System for Electric Vehicles—Part 1: Functional Requirements and System Architectures
SAE J2293 establishes requirements for Electric Vehicles (EV) and the off-board Electric Vehicle Supply Equipment (EVSE) used to transfer electrical energy to an EV from an Electric Utility Power System (Utility) in North America. This document defines, either directly or by reference, all characteristics of the total EV Energy Transfer System (EV-ETS) necessary to insure the functional interoperability of an EV and EVSE of the same physical system architecture. The ETS, regardless of architecture, is responsible for the conversion of AC electrical energy into DC electrical energy that can be used to charge the Storage Battery of an EV, as shown in Figure 1.
The different physical ETS system architectures are identified by the form of the energy that is transferred between the EV and the EVSE, as shown in Figure 2. It is possible for an EV and EVSE to support more than one architecture.
This document does not contain all requirements related to EV energy transfer, as there are many aspects of an EV and EVSE that do not affect their interoperability. Specifically, this document does not deal with the characteristics of the interface between the EVSE and the Utility, except to acknowledge the Utility as the source of energy to be transferred to the EV.
The functional requirements for the ETS are described using a functional decomposition method. This is where requirements are successively broken down into simpler requirements and the relationships between requirements are captured in a graphic form. The requirements are written as the transformation of inputs into outputs, resulting in a model of the total system.
Each lowest level requirement is then allocated to one of four functional groups (FG) shown in Figure 2. These groups illustrate the variations of the three different system architectures, as the functions they represent will be accomplished either on an EV or within the EVSE, depending on the architecture. Physical requirements for the channels used to transfer the power and communicate information between the EV and the EVSE are then defined as a function of architecture. System architecture variations are referred to as follows:
Type A—Conductive AC System Architecture—Section 7.2.1
Type B—Inductive System Architecture—Section 7.2.2
Type C—Conductive DC System Architecture—Section 7.2.3
The requirements model in Section 6 is not intended to dictate a specific design or physical implementation, but rather to provide a functional description of the system’s expected operational results. These results can be compared against the operation of any specific design. Validation against this document is only appropriate at the physical boundary between the EVSE and EV. See Section 8.
This document refers to both conductive (per SAE J1772) and inductive charging (per SAE J1773). A new SAE, Charging Communication Task Force has reviewed this document as it applies to both charging hardware systems (conductive and inductive) and applicability to the messages contained for the various energy transfer types (AC or DC conductive, inductive and on-board or off-board charger variations). This task force is also addressing new approaches as (1) the desire for bi-directional energy transfer from the vehicle to the utility grid (V2G), (2) updating the communication medium from SAE J1850 to either Power Line Communication (PLC) or wireless and (3) conforming to a major revision to SAE J1772 which includes a new set of connectors and signals between the EV and EVSE plus variations to AC and DC power levels. New vehicle architectures have also been introduced as Plug-In Hybrid (PHEV), Plug-In Fuel Cell Vehicles (PFCV) and may require unique communication aspects. Rechargeable Energy Storage Systems (RESS) have also changed dramatically since SAE J2293 was issued and new technologies along with packaging aspects may require specific communication criteria.
This is resulting in a major revision to our communication approach. In order to maintain information for existing systems or future vehicles that desire to use existing systems, this SAE J2293 task force plans to reaffirm SAE J2293 which preserves the existing information. A new J-document will be assigned to use the SAE J2293 basis, then add and delete info that address the new criteria listed above. It is planned to be specific to these needs and not include inductive charging aspects as no new changes are anticipated for that technology.
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Also known as: SAE J 2293/1
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