DC-link and Machine Design Considerations for Resonant Controllers Adopted in Automotive PMSM Drives

This study presents an analysis of the harmonic content on the dc-link (battery) side in electric drives with permanent-magnet synchronous machines (PMSMs) adopting fractional-slot concentrated windings (FSCWs) which can have a significant harmonic content. An analytical expression for predicting the ripple content in the dc-link (battery) current utilising data from a two-dimensional finite element method (2D-FEM) based model is presented and found to be in good agreement with corresponding experimental results. The FEM model is also used to demonstrate that the resulting harmonic content in the phase currents when operating at speeds well above the bandwidth of a conventional proportional + integral type controller can result in a substantial increase in magnet losses. Finally, a previously reported, experimentally evaluated model of an automotive traction battery and the associated battery cable is combined with an implemented model of the FSCW-PMSM (utilising data from the 2D-FEM model), converter and control to predict the resulting harmonic content in the battery current. The presented methods can be utilised when analysing the impact of harmonics on both the ac and dc sides of an automotive electric drive system.