Promotie G.R. Chandra Mouli: elektrische auto's
Charging electric vehicles from solar energy: Power converter, Charging algorithm and System design. Promotor 1: Prof.dr.ir. P. Bauer (EWI); Promotor 2: Prof.dr. M. Zeman (EWI).
Electric vehicles (EVs) are only sustainable if the electricity used to charge them comes from renewable sources and not from fossil fuel-based power plants. In this thesis, a 10kW solar powered charger for electric vehicles and charging algorithms for controlling it have been developed. The charger allows electric cars to be sustainably charged from photovoltaic (PV) panels and from the grid if the sunshine is insufficient. The charger is bidirectional, so the EV battery can provide power back to the grid, referred to as vehicle to grid (V2G). Hence, the car battery to be used as a storage for PV.
The charger facilitates EV and PV to directly exchange power on direct current (DC), which is more efficient than the current approach of exchanging power over alternating current (AC). The charger can accomplish four power flows: EV -> PV, EV -> Grid (V2G), Grid -> EV, PV -> Grid. The converter is based on high-frequency power electronics and quasi-resonant technology and uses wide bandgap silicon carbide (SiC) devices, which are better than traditional silicon-based devices. This has resulted in a higher peak efficiency (>96%) and partial load efficiency and three times higher power density (400W/ltr), when compared to existing solutions based on AC power exchange. Further, the 10kW modules are modularly built and hence can be operated in parallel for fast charging applications up to 100kW. The charger is compatible with the CHAdeMO and CCS/Combo charging standard and successful tests have been done with commercials EVs.
In this thesis, new charging algorithms are developed that integrate several applications of smart charging like charging based on PV forecast, EV user preferences, multiplexing of EVs, V2G demand, energy prices, regulation prices and distribution network constraints. Currently, algorithms focus on one or few applications at a time, resulting in a small reduction in net costs. With the new approach, the benefit of each application adds up, thereby reducing the net costs significantly. For two specific case studies simulated for Netherlands and Texas, the algorithms reduced the net costs by up to 427% and 651%, respectively.
The charger was co-developed with two companies PRE and LMS and is now commercially available via PRE. The charging algorithms were co-developed with the University of Texas at Austin. The project was funded by TKI Urban Energy.
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