A Study on Optimal Combinations of Winding and Cooling Methods for Downsizing Power Units in Motorcycles

<div class="section abstract"><div class="htmlview paragraph">In commercially available electric motorcycles, there is a notable shift in the cooling method, moving from air cooling to water cooling, and in the winding method, moving from concentrated winding to distributed winding, as the output increases. This shift occurs around 8 to 10 kW. However, there is a paucity of empirical investigations examining these combinations to ascertain their optimality.</div><div class="htmlview paragraph">In order to verify this trend, a verification model has been constructed which allows for the comparison of the capacity and weight of the motor and cooling system according to the vehicle’s required output and thermal performance.</div><div class="htmlview paragraph">A comparison and verification of the combinations of winding methods (concentrated winding or segment conductor distribution winding) and cooling systems (water-cooled or air-cooled) was conducted using the model that had been constructed.</div><div class="htmlview paragraph">In the motor designed for this study, when the maximum output of the vehicle was 35 kW or less (European A2 license), the total volume of the motor and cooling system was found to be the smallest for the air-cooled concentrated winding motor. However, in the 15 kW and above range, it was found that the volume of the water-cooled Segment conductor (SC) winding motor, including the cooling system (radiator, hoses, pump, reservoir tank, cooling water), was approximately 110% of the air-cooled concentrated winding motor, and the weight was approximately 65% or less. These findings are generally consistent with the observed trend of an increasing adoption of water-cooled distributed-winding motors in commercially available electric vehicles (EVs) with a power rating of approximately 10 kW.</div></div>