SLOVENIAN ELECTRIC VEHICLE
The concept of a city electric car
SEV project involves the development and construction of a small electric vehicle (EV) for short travel distances in:
– Urban environment
– Rural environment
– Car sharing system
Car sharing is becoming a modern way of using personal vehicles, which requires some adjustments for better sharing.
The development and implementation of SEV project are focused primarily on energy saving and efficient energy recovery through regeneration during braking, downhill driving, and also the fluctuation of the overall mass of the vehicle and fill the gap between a bicycle or motor-bicycle and a Class N passenger car. Energy efficiency depends mainly on weight, air resistance and properly selected propulsion system. The target value of energy savings is 50 Wh/km (5 kWh/100 km). Currently, energy consumption of the current technology is in the range of 180 Wh/km – 220Wh/km (18 kWh/100km-22 kWh/100 km). The possibility to be able to produce EV with less power consumption was confirmed by the VW-project XL-1 (/en.wikipedia.org/wiki/Volkswagen_1-litre_car).
For a successful , it is advisable to consider certain technical bases:
- energy efficiency and energy regeneration
- minimum weight
- minimum air resistance
- degradability of the vehicle
- simple maintenance and cleaning of the vehicle
SEV project is based on these recommendations, as can be seen from the following presentation:
SEV project involves EC type approval for two and three-wheeled motor vehicles (L7e, L6e).
The base platform is based on a self-supporting chassis with bodywork made of composite materials (carbon) and with the technology of spraying the material into dedicated devices. The chassis is designed and manufactured in a drop-shaped form, which provides a good aerodynamic effect (Cx = 0.2) and a strong ending at the rear end with a safety bow in the form of an aerodynamic wing that prevents damage to passengers in the event of rolling of the vehicle. The chassis is also structurally reinforced against side impacts.
BATTERY ASSEMBLY, STORAGE SPACE:
Passenger space at the front is reserved for the battery pack (Li Fe PO4.10 kWh, 48V) and also the storage area (300 l) for personal luggage above the battery pack.
The dashboard is minimal, equipped only with statutory instruments and switches, and instruments for monitoring energy parameters (energy consumption, voltage, current etc.). The dashboard does not include various large displays that negatively affect the concentration of drivers, similar to TV, phone, smoking etc.
The innovative power train drives the rear wheels with a narrowed track (420 mm) via two electric motors (3 kW + 3 kW, 48 V) and automatic transmission (CVT). The introduced power train allows optimal torque utilization which greatly reduces the impact of start-up currents and is sufficient for the top speed (80 km/h), acceleration (0-60 km/h in 8 seconds), and also a solid speed on slopes (20%) (40-50 km/h); all of which greatly influences the prolongation of battery life.
The batteries in the battery pack (10 kWh) are typically charged via domestic wiring (220/380 V) in three hours (220 V) or in one hour (380 V). The batteries in the battery pack can also be recharged at high-speed charging locations, but this is not recommended due to higher energy loads which negatively affect the battery life.
During the winter period, the heating system is regulated by an independent bio-fuelled heater which does not put stress on the capacity of the batteries.
All built-in lighting units are in LED technology, except for short-long beam lights, those use xenon technology.
The good side of the electric power plant is in the characteristic that, in case of braking or downhill driving, the direction is diverted from driving direction to the generator direction, thereby generating electricity and storing it in the batteries of the battery pack. Electric energy can also be obtained while driving, where swing energy of the mass of the EV is exploited and stored in the batteries via electricity-generating dampers. Solar energy that works on the vehicle, especially in favourable weather conditions, is also stored in the batteries of the battery pack via solar cells. The goal of SEV project is to save up to 50% of additional energy.
It is known that maintenance of the EV is less demanding due to the smaller number of rotating parts. SEV project is even more user-friendly with less loaded and simpler parts that are integrated in the EV. This also means a longer lifespan of the EV.
Every device – including an EV vehicle – needs to be decommissioned after its lifetime and, if possible, use waste materials in further production. Materials installed in SEV project are standard (battery problem is global) therefore decommissioning also complies with current standards.
SEV project is also designed for the car sharing system. This system raises some additional questions, especially with regard to cleaning the vehicle between individual transfers. During this period, this is not yet satisfactory according to the available information. Perhaps this is unseen due to minor activity. Certain problems may be expected with the expansion of the system. There are no final solutions yet, there are certain ideas that are not yet technologically advanced, but there is a great chance of final success.
STATE OF THE PROJECT:
The basic idea comes from the 1990s, when a study was conducted on the transport habits of Slovenians. This has not changed until now (one vehicle – 1 to 2 persons). Already at that time, the production of a small gasoline engine and a three-litre fuel consumption per 100 km were considered. The problem arose on how to make a lightweight and safe two-seat vehicle. Because of state of technology and other technical barriers at the time, this was a great challenge that was not realized. In the later years (2004, 2005, 2006), new technologies (composites, Lithium batteries, electric motors with control etc.) appeared which led to a new drive in the electrification of vehicles on the market. The first attempt to produce a lightweight passenger car (EV) was made. It was tested on local testing areas. During 2012-2018, the second EV prototype was completed and tested. At this stage of development, there has also been a need to improve and transform some components. By continuing the development of the EV and adapting to SEV project, it is ready for new testing.
NEXT DEVELOPMENT STEP:
It is necessary to prepare the technology and production capacities for producing the test quantity (approx. 20 vehicles) for the purposes of type approval, sales activities, preparation of investment activities etc.).
Production in Slovenia exists only in Novo mesto (REVOZ – SMARTWO EV). However, there are a considerable number of modified standard passenger cars on fossil fuels. Modification volume is expressed in the replacement of a standard motor with an electric one and the installation of suitable battery pack and other elements that are required for the operation of the entire system. Such modified cars have similar driving characteristics and cannot be compared to properly designed electric cars (weight, air resistance, etc.). All remaining EVs and hybrid vehicles are brought from the rest of the world and are generally in a higher price range. Direct competition comes from EVs produced in China. They are competitive in price, but they do not meet European expectations in terms of quality.
SEV project foresees the achievement of a competitive price up to (10 000 EUR) and in technical terms, the appropriate weight, reduced air resistance, improved regenerative process, the combination of which means lesser consumption of electric energy compared to competing EVs. The interior is spacious with a good overview of traffic and competes with EVs in the higher price range segment. It is also designed for the car sharing system; the SMARTWO EV is also part of this system which is welcome comparative information between SEV project and SMARTWO EV.
|SEV ccc||SMARTWO EV|
|Number of seats||2||2|
|Electric motor (kW)||6||41|
|Acceleration 0-60 (s)||8||4,9|
|Max. speed (km/h)||80||130|
|Battery capacity (kWh)||10||17,6|
|Battery type||Li Fe PO4||Li ion|
|Charge time – house inst. – 0 – 100 % (h)||3||4,9|
|Energy consumption (kWh/100 km)||4-6||15,8|
|Dimensions L x W x H (m)||2,45 x 1.5 x 1,5||2,7 x 1,6 x 1,5|
|Track front / rear (m)||1,15/0,42||1,47/1,43|
|Turning diameter (m)||5,2||7,0|
|Cargo volume max. (L)||300||350|
|Price (EUR) -EU||10 000||25 000|