Design Criteria for EV Drivetrain

Designing and testing of electric vehicles (EVs) is a time-consuming process because of the iterations involved in the electric machines (EMs) and their power electronics (PEs) designs. Most of the time, both designs are done sequentially by using the output of the machine design step for proper sizing of its PEs. This paper proposes a novel fast and systematic method that sets a common ground for electric machine design and drive engineers allowing them to work in parallel and speed up the EV drivetrain development process. The proposed method is based on estimating key parameters such as magnet flux linkage, the d-q axis inductances, motor terminal voltages, and currents based on the drive requirement in terms of torque-speed envelope and battery terminal voltage. A case study based on an industrial project has been performed to show the feasibility of the proposed approach on a 7.12 kW surface and inset permanent magnet synchronous machine (SPMSM and IPMSM) drivetrains. New equations have been developed for getting IPMSM parameters from a feasible SPMSM design. Design steps and performance characteristics using simulation and finite element analysis (FEA) software are discussed. The effectiveness of the proposed design approach is also validated using MATLAB Simulink.