With the present trend of reducing carbon emissions to the environment, electric vehicles (EVs) have become a popular topic for the scientific community and automotive-related industries. In order to increase the number of EVs on the road, customers’ main concerns: driving range, charging time, and vehicle price need to be addressed. These concerns can be resolved in a variety of manners, ranging from improving the chemistry to the charging units of the EV battery. This dissertation focuses on advancing the two types of charging units: plug-in and wireless, particularly improving the following crucial features: efficiency, reliability, size, and cost. The first half of the dissertation offers solutions for the plug-in technology, specifically in the power levels of extreme fast chargers (XFC), which will charge EVs within 10 minutes. Current XFC stations have a fixed charging-port configuration (CPC), using a single port to charge any EV type, which requires their power converters to be larger and more expensive than likely necessary. In this dissertation, a 13.8kV, 1.2MW XFC system with a CPC that adapts in response to the types of EVs connected is proposed. Theoretical analysis shows that the proposed CPC allows a station to have a 40%-66.7% smaller power rating compared to one using the conventional CPC, thus achieving a less expensive and smaller system.For safety reasons, the proposed XFC station as well as conventional plug-in chargers isolate EVs from the power grid with high-frequency transformers (HFTx), which are one of the most heavy, bulky, and inefficient components in the station. Traditional methods to specifically reduce the HFTx’s core loss are limited to their design and manufacturing, and typically rely on complex optimization algorithms. An online-based approach to reduce this loss is proposed in this dissertation, which relative to the conventional methods, is less time consuming to implement and can be easily applied in existing stations. Theoretical analysis and simulation results from ANSOFT Maxwell show a core loss reduction of 50% at light load, and of 80% at full-load. The second half of the dissertation presents solutions for the wireless technology, which enables EVs to re-charge while driven. Conventional single-phase wireless chargers rely on a two-stage power conversion to perform power factor correction (PFC) and to regulate power flow. To absorb the inherent “2ω” ripple flowing in the system, a large dc-link capacitor is used; which is sized with an equation that relies on a single operating condition. This sizing approach may cause reliability issues, and can inadvertently suggest that the station needs a larger and more expensive capacitor than needed. To overcome this limitation, this dissertation proposes a simulation-validated generalized equation that accounts for system control variables and the whole load range. The conventional two-stage charger inherently possess the following drawbacks: 1) extra semiconductor devices, as well as their corresponding heat sinks and control circuity, and 2) any accidental shoot-through in the dc-link can destroy the circuit. To eliminate the size, cost and power loss related to these semiconductors while improve the system reliability, a Z-source-based wireless charger is proposed. Not only does the proposed charger performs PFC and regulate the power to EVs in a single stage, it is also immune to shoot-through states. The system’s operation was experimentally validated, where a 0.987 power factor was achieved at full-load condition. The ideas presented in this dissertation provide designers with solutions that will ultimately lead to safer chargers and/or benefit the budget of EV owners and automotive-related industries. The solutions for plug-in chargers are helpful to accelerate mass adaptation of EVs, while the ones for wireless are more convenient in the long run.
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