A Scaling Procedure for Electrically-Excited Synchronous Machines Utilizing Flux and Loss Maps

Electrically-excited synchronous machines are a promising alternative to permanent magnet-based counterparts for traction applications. Besides being rare-earth magnet free, EESMs offer great flexibility of control and high efficiency over a wide range of speed and torque values. This paper introduces a rapid and precise method for scaling the dimensions of electrically-excited machines, leveraging a reference design as a starting point. The proposed procedure utilizes the pre-calculated flux and loss maps of one existing machine to ensure compliance with new peak torque and power, maximum operating speed, voltage, and current specifications, all achieved within minimal computational time. The efficiency map and operating limits of the scaled machine are rapidly derived without necessitating additional finite-element simulations. The efficacy of the procedure is demonstrated by scaling the electrically-excited traction motor of the Renault Zoe to match the performance of the permanent magnet synchronous motor found of the Nissan Leaf drivetrain.