Abstract
Research Questions/Objective
The trend of increasing fleet of electric vehicles and determines the extension of the geographical areas of operation, including the Northern areas with cold winter weather. Practically in all territory of Russia the average winter temperature is negative. With the winter temperatures can be below in Moscow -30°C, in Krasnoyarsk -50°C. Battery system can operate in a wide temperature range, but there are extremes that should be remembered all the time, especially in cold climates like Russia. In the operating instructions of the electric car Tesla ModelS indicate that to save the battery don’t use at temperatures below -15°C.
Methodology
In State Research Centre "NAMI" were conducted computational and experimental studies of the behavior of two battery modules comprising the battery system and manufactured on the basis of lithium batteries at low temperatures. Studied two battery modules housed in a sealed stainless steel containers. The first container had no insulation coating and the second container had an inner insulating coating and an integrated device for temperature control is built on a ventilated thermoelectric Peltier converters. The purpose of the research – development and validation of engineering and scientific proposals for significant extension of temperature range of operation high-capacity battery systems in the zone of negative temperatures. The research was carried out in the temperature range from 0°C to-30°C. Theoretical calculations showed correlation with the experimental results with a deviation of not more than 5%.
Results
The paper presents the dependence of the cooling time and heating of the battery cell at different ambient temperatures and provides guidance on allowable cooling time while using and not thermally insulated thermally insulated containers. Shown the inappropriateness of the use of active heating of the batteries of the battery module with the limitation of the maximum heating temperature. Suggests using the temperature control on the basis of thermoelectric converters Peltier connection from the onboard electrical network of the electric vehicle.
Limitations of this study
Important limitations of this study were: temperature of ambient air not below -30°C, relative humidity of 45 to 80 % and atmospheric pressure from 630 to 800 mm Hg.
What does the paper offer that is new in the field including in comparison to other work by the authors?
A method of calculating the required power input of thermal energy to ensure a comfortable operating temperature of battery units with batteries of different electrochemical systems. Proposed technical implementation of the application on the basis of thermoelectric converters Peltier.
Conclusions
The use of the proposed technical solutions will allow to ensure the operation of electric vehicles under conditions of low and very low temperatures, which will significantly expand the geographical area of their application.
Key Words : Electric vehicle, energy efficiency, thermostatics, cooling system, heating up.