Transient analysis of three-phase high-power voltage source inverter with nonlinearities in hybrid electric vehicles

Abstract

High-power three-phase voltage source inverter (VSI) is used in the drive line of hybrid electric and electric vehicles mainly to drive the traction motor. VSI is supplied by battery on board, which gets charged and discharged under various control strategies in these vehicles. Throughout a drive cycle, the control signal to the VSI keeps changing. The high switching frequency of power electronics devices increase the stress on the VSI. The response of a three-phase VSI under these circumstances has been studied in this paper. The transient analysis of VSI including nonlinearities has been done using axis transformation and average and canonical modeling. The three-phase pulse width modulation signals are also linearized using d – q axis transformation in synchronous reference frame. It has been observed that a VSI is always a very stable system with nonlinearities and with reference to dc input variation but a very unstable inverse system with respect to the control signal. The results obtained are very important for the controller and observer design and also to study the effects of these transients on the mechanical components of vehicular drive line.