Average-value model for plug-in hybrid electric vehicle battery chargers

Abstract

Electric vehicle battery charger connected to the secondary distribution grid potentially raises power quality (PQ) concerns, thus the necessity of the analysis of its impact on the grid. Charger assembly consists of power electronic equipments that undergo fast switchings. It makes the device-level simulation very slow and impractical for PQ analysis and calls for an average model for the system. This paper presents an average-value model (AVM) for a single-phase generic battery charger of a plug-in hybrid electric vehicle. The proposed AVM includes a rectifier circuit and its filter, boost converter and battery banks. Average dynamics of the switching circuit are obtained by averaging the effects of fast switchings in the device that occur within a prototypical switching interval, resulting in a fast simulation model. Proposed AVM is validated against devicelevel time-domain model for a variable load and a battery load and found to be very accurate and robust in approximating the switching model and battery charging dynamics. It should be noted that a pulse width modulation (PWM) control algorithm for conditioning input current waveform is not included in the average value model, resulting in a non-sinusoidal supply current waveform rich in harmonics. A time-domain model with PWM controller is also developed and compared against the developed AVM model.