Stability modeling of HEV/EV electric drives as a small-scale distributed power system

Stability modeling of Hybrid Electric Vehicle and Electric Vehicle (HEV/EV) electric drives as a small-scale distributed power system is presented. Three fundamental questions in applying the impedance-based stability analysis are broached, those are “Is output/input impedance stability modeling sensitive to 1) input-output boundary location?, 2) power-flow direction?, and 3) voltage-stiff or current-stiff representation?”. The validity of the answers to these questions presented in this paper is not restricted to vehicle electric drive applications. The stability modeling description is presented with an example of an HEV electric drive (e-drive) system consisting of a dc-dc converter and two three-phase inverters sharing a common dc-bus. It is shown that there is good correlation of the stability analysis results between the presented approach and the time-domain circuit simulations.