An Overview of EV Roaming Protocols

Abstract

Roaming in electric mobility (EV roaming) enables EV users to make use of any charging station belonging to other networks with only a single user registration based on roaming agreement between operators. This paper presents an overview of the functionalities of the four major existing EV roaming protocols, namely the Open Charge Point Interface (OCPI), the Open InterCharge Protocol (OICP), the Open Clearing House Protocol (OCHP), and the eMobility Inter-operation Protocol (eMIP). This paper focuses on how each EV roaming protocol works in terms of data exchange with the Open Charge Point Protocol (OCPP) which is the de-facto protocol embedded in many charging stations available in the market. Related actors and their roles that are defined in each protocol will be presented. Examples are given in the form of a sequence diagram in order to depict the interaction between actors in the case of user registration, start a charging session, stop a charging session, and billing. This paper concludes that employing the sequence diagram is one effective method to achieve a fast learning curve while studying the EV roaming protocols.