EV charging station
As a reduction of global warming and the pursuit of climate neutrality of the European Union by 2050, the European Commission has set a goal for the members of the European Union to reduce CO2 greenhouse gas by 55% till 2030.A way to reduce CO2 emissions is to switch from fossil fuel vehicles to electric powered vehicles. With the measures introduced by the members of the European Union through legislation and incentives for electric vehicles, they are becoming more and more economically acceptable and interesting. The novelty of electric vehicles compared to fossil fuel vehicles is that we can charge electric vehicles at home through the existing infrastructure. While the current drawback of electric vehicle battery charging is the charging time, which is still longer than refueling a fossil fuel vehicle. It is also important to note that the electricity that charges electric vehicle batteries is produced by power plants with renewable energy sources and power plants that use fossil fuels. The ratio of electricity produced from fossil fuels and renewable sources such as wind and sun is currently changing significantly in the direction of renewable energy with legislative incentives and a number of economic incentives.
TECHNICAL CHARACTERISTICS OF CHARGING STATION
The following table shows the main technical characteristics of electric vehicle chargers. The higher the power of the charger, the shorter the charging time. When choosing a charger, it is important to check that it is compatible with the electric vehicle in terms of socket type and whether the vehicle accepts direct current (DC) or alternating current (AC) charging.
| Name | Measurement unit | Example |
| Current type | volt [ V ]; AC/DC ; br. faza | 230 V AC 1P+N400 V AC 3P+NDC |
| Charging voltage | voltage[ V ] | 485 V DC400 V AC |
| Max. charging current | ampere [ A ] | 125A DC10 ÷ 63A AC |
| Charger el. power | kilowatt [kW] | 2 ÷ 44 kW AC50 kW DC |
| IP protection(according to IEC 60529) | IP | IP 44IP 54 |
| Impact protection (prema IEC 62262) | IK | IK 10 |
| Atmosphere temperature for safe charger work | degrees Celsius[ °C ] | -30 ÷ +50 °C-25 ÷ +40 °C |
| Socket type (prema IEC 62196) | Type 1Type 2CHAdeMOFF (CCS Combo 2) | |
| Authentication type | – Authentication with RFID cards – Mobile/web application |
CHARGING TIME APPROXIMATION
The charging time of an electric vehicle can be estimated based on the power of the charging station and the electrical vehicle battery capacity.
For example, a 50kWh battery, with a 5 kW ac charger in the vehicle and a type 2 electric vehicle charger connected at home to a classic 2.3 kW electrical outlet. By estimation, we arrive at a charging time of the entire battery of 21 hours and 45 minutes.
CHARGER TYPE
IEC 61861 je norma za sustave punjenja električnih vozila, dok IEC 62196 je norma koja definira izgled utičnica/konektora na automobilu i kabelu kojim se povezuju punjači i električna vozila. Prema IEC 61861 postoje 4 tipa punjenja električnih vozila, a to su:
- Type
Connection to a classic household socket. Chargers should be limited to 16 A 230 V AC for a single-phase charger or 3×16 A 400 V AC for a three-phase charger.
This type of charging has no additional protection and must be provided in its own low-voltage installation.
- Type
Connection to a classic home socket on the side of the home electrical installation and connection to a type 1 or 2 connector on the side of the electric vehicle. The charging cable has charging control functions and personal protection against electric shock, integrated into the connection cable, between the standard plug and the electric vehicle. Chargers should be limited to 32 A 230 V alternating current for a single-phase charger or 3×32 A 400 V alternating current for a three-phase charger. This mode is limited to domestic electrical installations. The connection cable is usually supplied with the electric car.
- Type
Electric vehicles are charged with special equipment, called an EV charging station (or EV charger), permanently connected to the AC power grid and integrated protection and control functions. Since a dedicated installation is used, the charging power is higher than in type 1 and 2, and ranges from 3.7kW to 22k.
- Type
Charging is done through equipment for powering DC electric vehicles connected to the AC or DC power supply network. The charger delivers direct current directly to the battery, eg bypassing the built-in charger. Charging an electric vehicle can be done much faster than in modes 1, 2 and 3, since the electric charging power range is greater than 24kW. In type 4, digital communication between the electric vehicle and the equipment supplying the electric vehicle is mandatory and should comply with the requirements described in IEC 61851-24.
ELECTRICAL INSTALLATION
When charging electric vehicles at home, it is important to keep in mind that the charger is not a classic household appliance in terms of protection and operating mode of the appliance. Unlike a washing machine, which only requires a higher electrical power at short intervals, the charger of an electric car continuously consumes constant power for several hours. The order of magnitude of the connection power of a washing machine is around 2 kW, while electric vehicle chargers range from 2 kW to more.
Regarding the protection of the electrical installation of the charger, it is important to consider a good selection of the residual current device (RCD, feed switch) and surge arrester (SPD).
In order to be sure that we are protected from electric shock, it is necessary to choose the correct RCD. Classic RCD type AC and type A is not sufficient protection because it does not protect us from all forms of fault current. During the operation of the electric vehicle charger, there is a possibility of a direct current error that the classic RCD type AC will not recognize. Also, in order to maintain the selectivity of the protection, it is necessary to have a RCD of the entire low-voltage distribution and a separate RCD device for each charger.
According to the German standard (DIN VDE 0100 722) and guidelines, chargers intended for charging vehicles in public areas must be protected by a surge arrester. Important input data for choosing a suitable surge arrester is knowing how the charger is connected, whether it is connected directly to the network or is connected through a building that has a lightning protection installation or not. Although it is not prescribed by the standard or legislation, and electric car chargers are not a cheap device, it would also be advisable to protect the device from overvoltage in the home installation.
LEGISLATION AND STANDARDS
Since there are no regulations and standards for the design of electric vehicle charging stations in Croatia, it is necessary to use an international standard such as IEC 60364-7-722 (Low-voltage electrical installations — Part 7-722: Requirements for special installations or spaces — Electric vehicle power supply ) and good technical practice. Slovenia also does not have regulations that would define design rules, and for this reason the Slovenian Chamber of Engineers has issued a “PRIROČNIK ZA PROJEKTIRANJE POLNILNIH POSTAJ ZA ELEKTRIČNA VOZILA”.
FIRE PROTECTION
Electric vehicle batteries are designed to be low flammable, but once ignited their burning is self sustainable. The very fact that the burning process of batteries is self sustainable, makes it difficult to extinguish. The biggest risk for the battery of an electric vehicle to catch fire is during the charging process.
In the event of a battery fire, it is important if it is possible to disconnect the electric vehicle from the charger if it was connected. Cooling the battery with water reduces the possibility of an explosive reaction and battery explosion, but water cannot extinguish a battery fire. For extinguishing fires, a special water-based agent has been developed that optimally extinguishes electric battery fires.
To completely extinguish a battery fire, it is necessary to completely immerse the battery for a certain number of hours into salty water. In the case of electric cars, entire cars are immersed in a container of salt water. In the impossibility of putting the car in the container, a tool was developed that penetrates the car to the battery and fills it with a specific battery extinguishing agent.
In the case of installing the electrical vehicle charger/charging station at home, leave it to trained people, or if the system is plug&play, definitely consult with an expert whether your existing electric installation is correct for the new type of electrical device.