Dynamic Wireless Charging of Electric Vehicle

Wireless battery charging (WBC) is an attracting solution to promote electric vehicles (EVs) in the market, which may provide superior charging infrastructure and unlimited driving range. The most suitable technique to implement WBC is inductive power transfer (IPT) with a coupling established between two distant coils, one buried into the road and another installed in EV, and the power transferred from the buried coil to that onboard EV through a high-frequency oscillating magnetic flux. WBC can be carried out with EV that is either standing (while parked) or moving (on the road); the two WBC modes are termed static wireless charging (SWC) and dynamic wireless charging (DWC), respectively. However, this thesis focusses on the DWC, where an IPT track is buried into the road whilst the coil onboard EV, commonly termed pickup, remains coupled with the track to get power while moving on the road. The in-moving vehicle charging has been researched and demonstrated by some institutes across the world using two possible track arrangements: stretched and lumped coil track. The former one is composed of a single elongated coil, much longer than the pickup size, and the later one is an arrangement of multiple coils placed one next to the other, the length of them being comparable to the pickup size. A lumped track permits activation/deactivation only of the coil interacting with a pickup. This ability is called segmentation and is very important for DWC to reduce the losses and to avoid exposing the people to electromagnetic radiations; therefore, a lumped track has been dealt with in this thesis. The contactless power transfer at large airgap is possible with high frequency (in kHz) and high-magnitude current supply of the track coils; as increasing supply frequency improves power transfer efficiency. Apart from the supply characteristics and the coil dimensions, power transfer capabilities of a the system depend upon the coupling properties of the coil pairs, thus a pair polarized coils (also called DD coils) has been found more suitable for DWC due to its coupling merits at misalignment. Considering a lumped track composed of equally distant several DD coils, power and energy transfer to an EV moving on the track have been analyzed. Based on that, lumped track layout and its design procedure have been discussed in detail with an example of an EV. Segmentation of a DWC track is very important function, as mentioned above, which can be obtained by various methods and one of them is using the impedance reflected into a track coil from the coupled pickup. In this way, four compensation topologies have been discussed to investigate their reflexive properties (resistance and reactance) when they are deployed in a pickup circuit. Summarizing the outcomes and comparing their behavior, two topologies have been found useful for the track segmentation. Considering them, further analysis has been done to obtain and discuss their performance figures. This thesis also discusses about the power converters in both track side and pickup side circuit. The track side power converters include rectifier, power factor correction circuit and inverter, which extract power from the supply grid and transform into the appropriate form to realize efficient WBC. Converter arrangement in the pickup circuit includes rectifier and chopper to charger a battery using the received power