Timeout Reduction Algorithm for Efficient V2G Communication

Abstract

Recently, Electric Vehicles (EVs) using battery charging method and Smart Grid to optimize energy efficiency are being developed due to environmental issues among many other reasons. To exchange different information between EV and Smart Grid, Vehicle-to-Grid (V2G) communication is in use where V2G communication is defined in the international standards ISO/IEC 15118. Among the standards, ISO/IEC 15118-2 defines such things as V2G messages, timer, and timeout. This standard defines about two timeouts. The first is the Electric Vehicle Communication Controller (EVCC) message timeout. When EVCC message timeout occurs, EV terminates the communication session. Since EV does not send any message to Electric Vehicle Supply Equipment (EVSE) when it terminates its communications session, EVSE is does not know that the communication session of EV has ended. Therefore, the only way for EVSE to end its communication session is only through Supply Equipment Communication Controller (SECC) sequence timeout. The second case of timeout is the SECC sequence timeout. EVSE terminates its communication session when SECC sequence timeout occurs. Since EVSE also does not send any message to EV when it ends the communication session, EV does not detect the termination of communication session from EVSE. Therefore, the communication session of EV is only terminated when EVCC message timeout occurs. EV and EVSE do not share the termination of its communication session. Therefore, even if EV (or EVSE) ends the communication session, EVSE (or EV) wastes time by maintaining the communication session until timeout occurs. Also, if the vehicle user fails in charging and restarts the charging process, timeout can occur in the same sequence. Therefore, this thesis suggests that EV (or EVSE) sends timeout error message to EVSE (or EV) when timeout occurs in EV (or EVSE) before stopping its own communication session as a solution to the problem explained above. By the given method, 59.806 sec can be saved when EVCC message timeout occurs. In another case, minimum of 0.07 sec to maximum of 24.884 sec can be saved when SECC sequence timeout occurs. Also, by EVSE sending timeout error message to secondary actor, a new method of notifying timeout during a charging process is suggested.