Power sizing of wireless power systems feeding in-motion electric vehicles at constant power

The paper is concerned with the wireless power (WP) systems feeding in-motion electric vehicles (EVs) and focuses on the power sizing of three key WP system components, namely the track coils, the pickup and the voltage supply. It is assumed that the track is made of lumped type with no overlapped coupling of the pickup, and that the track coils and the pickup are compensated for by series resonating capacitors. Power sizing equations are formulated for a WP system that is controlled in the way of transferring a constant power to EVs during their motion over a large part of the track coils. Due to the variation of the coupling between the pickup and a track coil, the transfer of a constant power requires the adjustment of the currents in the WP system, obtained by commanding the embedded power conversion units. Two solutions are examined: by one solution, the pickup side current is controlled at a proper value whilst the track side current is regulated at a constant level; by the other solution, the opposite occurs. Power sizing equations are expressed in terms of specifications and parameters of the WP system. The equations outline that the power sizing is higher for the components in the side where the current control is executed. At last, the case study of a WP system is examined, showing the convenience of the track-side control.