International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 09 Issue: 09 | Sep 2022
p-ISSN: 2395-0072
www.irjet.net
Design of Cooling System for Permanent Magnet Synchronous Motor ina Formula Student Electric Vehicle Siddharth Yadav1 Student, School of Mechanical Engineering, Dr. Vishwanath Karad MIT World Peace University Paud Road, Pune, Maharashtra
---------------------------------------------------------------------***--------------------------------------------------------------------Abstract - The efficiency of the electric powertrain is of motor windings by 10oC will increase the winding approximated to 90% which is significantly higher when losses by 4%. The last reason for need of cooling system is compared to the vehicles propelled using the internal reduction permeability of magnetic steel due increase in combustion engines. The loss of energy in the electric temperature. It eventually leads to reduction in available motors is due to factors like eddy currents, winding torque as the magnetic field is weakening. resistance, friction and unbalanced change in load leading to sudden drawing of excess current. In order to dissipate Depending on need of heat dissipation and fluids the heat developed by the electric motor, conventional available heat transfer, there are two types of cooling heat transfer system is being developed where water is systems commonly used for automobiles, namely – Air used as a coolant and circuited around the fluid jacket Cooled and Water Cooled. Air cooled motors are the near the motor windings for convection of heat. The water simplest method of cooling the components of the motor . is then passed through a heat exchanger with the help of In simple words the air is pulled through small openings the pump and then recirculated through the water jacket. in the casing of the motor . Due to the rotating parts it The Normal Transfer Units method is used for heat passes through the entire structure and is then expelled transfer calculation . out . For increasing the efficiency of this system a fan can be installed on the shaft of the motor . The Cooling fan Key Words: Cooling System, PMSM, Electric Vehicles, helps in pulling the air forcefully through the motor . As a Normal Transfer Units. result , it increases the flow rate of the air and hence increases the overall heat transfer of the system . 1. INTRODUCTION Installing the fan also assures that there is continuous flow of air through the cooling circuit . The advantages of With significant development in cell chemistry of an air cooled motor is that it is a low cost system , no need the Li-ion cells, the electric vehicles have significantly of any external power source , high reliability and good increased the demand for short distance travels or city cooling at the ends of the winding . The major drawback is commutes. During to the stop and go traffic conditions, that this system is highly influenced by the external factor the electric vehicles provide excellent starting torque. like the ambient temperature , dirty air , etc. We have no But the same situation has an adverse effect on the control over the cooling and there is almost no airflow electric motor due unbalanced current loads. Hence, it is when the vehicle is stationary. For high power density necessary for the electric motors to have a cooling motors , water cooling is generally employed as the air system to maintain its lifecycle. The electric motors have cooling method is not sufficient . The two main topologies different grades of insulations such as F type or D type are water jackets in the housing of the machines or ducts which is commonly observed in PMSM motors. These inside the machines . This method is also called as insulations are rated for temperature of approximately indirect method of the cooling as the cooling medium is 120oC and a life period of 20 years. But the Arrhenius not directly in contact with the components . Water is Law states that, increase in temperature of 20oC above used as primary used as the cooling the medium as the the rated one reduces the insulation life by half. overall heat transfer coefficient of water is very high .. A Therefore, if the motor becomes too hot, the windings water pump is needed to flow the water through the will prematurely fail. Another reason for need of cooling water jackets and further pass it through the heat system is the motor efficiency. Copper has a positive exchanger. The major advantage it provides is uniform temperature coefficient of resistance, as a result increase cooling of the motor windings. in temperature of motor leads to higher winding resistance and lower efficiency. Increase in temperature
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