With increasing number of electric vehicles (EVs) on the road and many automotive companies pledging to phase out petrol and diesel vehicles to go completely electric, there is need for investments in EV Charging infrastructure to ensure that there are enough charging facilities to address a consumer's concern of reliable charging access irrespective of location and distance. With the rise in innovation in the EV charging infrastructure, there is also a need to ensure the interoperability between various components within the charging infrastructure. This paper proposes an open charge point protocol (OCPP) compliant software communication interface component for a DC fast charging station that establishes a communication between the electric vehicle (EV), electric vehicle supply equipment (EVSE) and the central management system (CMS) using shared memory approach of inter process communication. This interface also ensures simultaneous charging for two vehicles.
TopIntroduction
Globally there has been rising concerns over pollution, fuel crisis and climate change. International commitments are being made to limit the greenhouse gas emissions, enabling the automotive industry to go green and move towards E-mobility (Open vs. Closed Charging Stations: Advantages and Disadvantages, n.d.). DC Fast Charging Stations reduce the charging time to 30 mins to ensure the wait time to charge the EV is also reduced and addresses the range anxiety of the EV user.
Standardization bodies like ISO and IEC are defining standardization landscape for front end issues in E-mobility in domains like plug-ins, charging topologies, communication, safety and security to ensure interoperability of charging infrastructures (Schmutzler, Andersen, and Wietfield, 2013; IEC Smart Grid Standardization Roadmap, 2010). For the back-end communication the commonly used protocol is the open charge point protocol (OCPP) which provides a bidirectional service to communicate Charging Station, also referred to as ChargePoint with the Central Management System (CMS) (Open Charge Point Protocol 1.6, n.d.).
To ensure less wait time in EV charging facilities, it is important to have electric vehicle supply equipment (EVSE) with multiple charging connectors to ensure that multiple vehicles can be charged simultaneously. It is also important to ensure that the operator of the charging station can monitor and control the charging activity remotely in real time.
To ensure interoperability between various communication standards and protocol in the charging infrastructure there is a need for smooth information exchange between various components of the charging infrastructure.
There are various existing OCPP based implementation for charging infrastructure. Ravindran et al. (2020) describes a communication and user interface complying with OCPP for AC chargers. Devendra et al. (2021) describes the design and fabrication of an EV charge point based on the OCPP communication standard and complaint with the one M2M platform for level 2 charging standard. Devendra et al. (2021) also describes the hardware, software, and protocols followed to design the Level 2 charging standard electric vehicle charging station (EVCS).
In this paper, we propose a software communication interface component for a DC Fast charging station to control and monitor EV charging activity through central management system, which is responsible for managing the charging station, remotely. The proposed system is designed such that two vehicles can be charged simultaneously without one charging session affecting the other. Although the system has been prototyped for charging two vehicles at the same time, it can be extended for multiple charging connectors. This is achieved by running multiple software processes associated with each charging sessions concurrently. Shared memory based inter processing communication method is the novel approach employed to the proposed interface to enable exchange of data and communication between all the processes running concurrently and ensuring interoperability of the charging station with OCPP.
The remainder of the paper is organized in the following way. Section two describes the communication standards and protocols used in the implementation. Section three covers the proposed system for the DC fast charging system. Section four describes the implementation of the proposed system. Results of the implementation are described in Section five. Conclusion is depicted in Section six.