Motor Design Ltd will be presenting on multiple topics at this year’s virtual IEMDC.
Wednesday 19th May │ 1:30 pm – 1:45 pm EDT │ Slot Water Jacket Cooling System for Traction Electrical Machines with Hairpin Windings: Analysis and Comparison – Giada Venturini, Research Engineer
This work aims to analyze and compare the electromagnetic and thermal behaviour of two commonly used electrical machines in the automotive field: an induction motor and a brushless permanent magnet one, here equipped with slot water jacket cooling systems. The same stator design, drive management and winding layout, with hairpin conductors, are adopted for both machines. Four different slot cooling system design arrangements are investigated, keeping the same overall machine volume. Both motors are simulated with the proposed cooling system arrangements. Loss analyses are carried out to evaluate the impact of the different channel positioning inside the slot and their effects on the electromagnetic performance. In the end, the best cooling solution is identified for each machine, highlighting the main differences between the two machines’ behaviour, in addition to proving the cooling system topology goodness for hairpin windings machine in the automotive sector.
Thursday 20th May │ 1:15 pm – 1:30 pm EDT │ Optimisation of Hairpin Winding in Electric Traction Motor Applications – Dr. Shaoshen Xue, Senior Research Engineer
This paper investigates the influence of number of layers and conductor size of hairpin windings of electric motors for electric vehicle applications. Firstly, the hairpin winding technology for electric motors is reviewed and key design rules are introduced. Based on these design rules, a traction motor with hairpin winding technology is modelled in a finite element analysis (FEA) software. The influence of the hairpin winding layers on the DC and the AC copper losses is investigated, based on the results obtained considering different operating points and drive cycles. The results indicate that using a higher number of winding layers does not always lead to higher efficiency. The trade-off between DC and AC losses under different operating points and drive cycles must be considered when designing for the optimal number of winding layers. Furthermore, using a larger conductor and higher fill factor for hairpin winding not necessarily lead to higher efficiency. In this study, the optimal conductor size for electric motors with hairpin windings is identified by carrying out optimizations considering drive cycle efficiency.
Thursday 20th May │ 1:30 pm – 1:45 pm EDT │ Efficient Calculation of PWM AC Losses in Hairpin Windings for Synchronous BPM Machines – Dr. Mircea Popescu, Chief Technology Officer
This paper focuses on the alternative current (AC) losses in hairpin winding variation due to the skin and proximity effects in synchronous brushless permanent magnet machines when supplied from a pulse width modulation (PWM) inverter. Considering a 200kW motor for an electric vehicle application, whose specifications are provided in the manuscript, three main methodologies are investigated to demonstrate the importance of these additional losses and how is possible to take them into account when modeling the machine performance. A more rigorous approach and two more time-efficient ones are utilized for the purpose, showing powerful ways of taking into consideration the pulse width modulation induced eddy currents losses in stator conductors since the early stages of the design process. A reduction ratio of 30:1 in computation time gives the proposed methodologies great merit not only in modeling single operating points, but over the full torque-speed characteristic, efficiency maps, and drive/duty-cycles analyses.