Open Charge Point Protocol

The logical structure of charging infrastructure is based on the open charge point protocol (OCPP). OCPP is the industry-supported de facto standard for communication between a charging station (CS) and a charging station management system (CSMS) and is designed to accommodate any type of charging technique. OCPP is an open standard with no cost or licensing barriers for adoption [Open Charge Alliance, 2018].

Open charge point protocol specification uses the term charging station as the physical system where an electric vehicle can be charged. A charging station can have one or more electric vehicle supply equipment (EVSE). An EVSE is considered as a part of the charging station that can deliver energy to one electric vehicle at a time. The term connector, as used in this specification, refers to an independently operated and managed electrical outlet on a charging station, in other words, this corresponds to a single physical connector. In some cases an EVSE may have multiple physical socket types and/or tethered cable/connector arrangements to facilitate different vehicle types, this is a manufacturer’s choice. For example, the EVSE might be integrated into a charging station and to look as just a part of that device, but it might just as well have its own casing and work outside of the physical entity (CS), for example a charging plaza with 20 EVSEs and connectors which communicates via one modem as one charging station to the CSMS is seen by OCPP as one charging station [Open Charge Alliance, OCPP 2.0 Part 1, 2018].

In OCPP 2.0, a Charging Station is modelled as a set of "components", typically representing physical devices (including any external equipment to which it is connected for data gathering and/or control), logical functionality, or logical data entities. Components of different types are primarily identified by a component name, that is either the name of a standardized component, or a custom/non-standardized component name, for new, pre-standardized equipment, vendor specific, extensions, etc.

Charging station (top level), EVSE, and connector represent the three major "tiers" of a charging station, and constitute an implicit "location-based" addressing scheme that is widely used in many OCPP data structures. By default, all components are located at the charging station tier, but individual instances of any component can be associated with a specific EVSE, or a specific connector (on a specific EVSE) by including EVSE or EVSE and connector identification numbers as part of a component addressing reference. Every component has a number of variables, that can, as appropriate, be used to hold, set, read, and/or report on all (externally visible) data applicable to that component, including configuration parameters, measured values (e.g. a current or a temperature)[Open Charge Alliance, OCPP 2.0 Part 1, 2018].

This data structure allows efficient management of the CSMS (Charging Station Management System), as telematics system by the CSO (Charging System Operator) due to data integration, addressing (defining the location), defining the functionality and precise determination of variables and units of measure. What's more, CSMS has a large interoperability considered as the ability to easily integrate third party systems, such as the operator of the power distribution system.

The OCPP 2.0 protocol consists of the following functional elements:

• Security
• Provisioning
• Authorization
• Local authorization list management
• Transactions
• Remote control
• Availability
• Reservation
• Tariff and cost
• Metering
• Smart charging
• Firmware management
• ISO 15118 certificate management
• Diagnostics
• Display massage
• Data transfer

Each of the above functional blocks requires separate devices installed on the charging station, separate units of measurement and an integrated data exchange protocol, in this case OCPP 2.0, for managing the EV charging process in real time.

Charging Infrastructure - Modes Description

Charging Stations can be distinguished into 2 major types:

• Stations with EVSE providing AC power supply
• Stations with EVSE providing DC power supply

Major difference between these modes is type of connection between charging station and the vehicles battery. It should be emphasized that the process of charging electric vehicle batteries is not only about connecting the voltage to the vehicle's socket. The charging station establishes communication with the vehicle's charging module to determine the charging parameters and to protect the process itself in terms of user safety. An example may be charging with DC which, depending on the battery charge level, runs in the "constant current – constant voltage" mode. This means charging with constant current at increasing voltage up to 80 % of the battery capacity, which allows you to quickly recharge it. After exceeding 80 % of the battery capacity, the current is decreased, with constant voltage, so the charging time becomes significantly longer. This protects the cells against overheating and irreparable damage.

Charging plug-in can be divided into charging with DC and AC in the following modes:

• Mode 2 - slow charging - Charging with alternating current is easily available from the mains power supply with 230 V AC supplying power up to 3.7 kW;
• Mode 3 - accelerated charging - three-phase alternating current up to 22kW. The limitation here is the vehicle charger, which is a "bottleneck" and parameters of charging process depends on its parameters;
• Mode 4 - rapid charging - in the case of DC charging, the vehicle battery is directly charged, without the use of a charger. The standard is 50 kW, but there are already available 150 – 350 kW chargers provisioning ultra-rapid charging (www.abb.com).

Connection of the vehicle to the charging station is carried out via a cable with the appropriate plug. The most popular connector standards, along with the power and charging time are presented in the following table.

source: own Table

AC charger / slow charger – internal use

This type of AC charging station is dedicated for use inside buildings such as private garages, parking lots, etc. The available configuration and example prices are based on price table of Garo Polska, company of the Swedish Garo Group which is primarily engaged in the electrical installations industry and shown in table below. Home-charger doesn’t support OCPP protocol, which makes it only local charging solution. The home charger cost spreads between 480 and 1,180 euro.

Other internationally active suppliers of charging station technology are e.g. Wallbox, Wallbe , ABB, Webasto or Siemens.

Source: own Table, Data based on Garo Polska

AC charger LS4 / accelerated charger – external use housing

This type of AC charging station is dedicated for external use in public space. Its great solution for open space parking lots, company owned charging places and stand-alone charging points. The housing is equipped in sockets instead of cables due to frequent damages of cables by users.

The available configuration and example prices of LS4 device are based on price table of Garo Polska, company of the Swedish Garo Group which is primarily engaged in the electrical installations industry and shown in table below. LS4 charger is available in multiple version, depending of functionality (power meters, user’s identity, etc.) and prices spreads from 2,140 to 4,380 euro. Other internationally active suppliers of charging station technology are e.g. Wallbox, Wallbe , ABB, Webasto or Siemens.

Source: own Table, Data based on Garo Polska

DC charger QC45 / fast charger - external use

This type of DC charging station is dedicated for external use in public space. This device is recommended for companies providing commercial services of EV charging due to rapid charging, large fleet operators or municipal companies for example public transport, waste management, water supply. The time for refuelling the battery is comparable with fuelling a gasoline vehicle.This type of infrastructure plays a crucial role in propagation of electromobility.

There’s only one configuration available, but it’s equipped with all necessary connectors as CCS Combo and ChAdeMo for DC charging and type 2 socket for alternative AC charging.

An example price of QC45 device is based on price table of Garo Polska , company of the Swedish Garo Group which is primarily engaged in the electrical installations industry. Currently, this model costs 26,000.

Charging infrastructure – associated costs

Cost of embedding the charging station is not only the price of device, but also associated costs such as preparing of base and surrounding, operation of placing the charger and technical inspections to ensure safety and performance. Moreover there is periodic necessity of updating, maintenance works and inspections – all this activities are related to the costs. Major associated costs are presented in tables below.

Source: own Table, Data bases on price table of EV Charge Partner Polska 

Source: own Table, Data bases on price table of EV Charge Partner Polska 

Prices are based on price table of EV Charge Partner Polska, official provider of technical support for Garo Polska – charging stations manufacturer.

Considering costs of settling down the charging station it must be emphasized there are some categories of costs closely related with local conditions. There are:

• land lease/purchase costs,
• permits and licenses for station construction,
• support of the development of electromobility,

These costs should only be included in relation to the specific location of the station, so it is difficult to compare them with each other.

References

Open Charge Alliance, OCPP 2.0 Part 0, 2018, available at https://www.openchargealliance.org/

Open Charge Alliance, OCPP 2.0 Part 1, 2018, available at https://www.openchargealliance.org/

Open Charge Alliance, OCPP 2.0 Part 2, 2018, available at https://www.openchargealliance.org/