Executive Summary : | As per Sustainable Development Goals (SDGs) set by the United Nations (UN), reduction of carbon footprint is a major concern for all the Nations. Most of the countries have already started to work in attaining sustainable developments through more and more inclusion of renewable energy sources (RES), as well as introduction of EVs in larger scale. Electrification of automotive sector enables sustainable energy sources, reduces noise and pollution. The International Renewable Energy Agency (IRENA) analysis states, one billion EVs may be available on roads by 2050 as per prediction. The exponential growth in EV and Plug in Hybrid Vehicles (PHEVs) have set an ever increasing trend towards reliable charging infrastructure. However, the commercial high power charging stations have a limited access due to certain reasons. Due to such difficulties, EV wall mount chargers (3.3 kW) are the promising alternative to the issue. These converters are designed considering IEC 61851 for Level 1 AC (230 V) charging without communication which can further be useful in Vehicle to Home (V2H) power transfer if implemented with bidirectional power flow capability. During the charging process, major challenges to be handled by the EV chargers, such as (a) power factor correction (PFC), (b) maintain better efficiency, (c) grid connected front – end converter performance, efficiency, cost, (d) higher voltage and current stresses on the devices. As per available topologies, wall mount chargers are mostly having unidirectional power flow capability, typically grid to battery side power flow is achieved. The charging process is maintained by two stages – a pre-regulation PFC circuit and an isolated DC – DC converter for supplying to the battery. A bulky DC-link capacitor is essentially to be included in between the two stages to eliminate low frequency current ripples. A highly efficient single stage bidirectional converter (BDC) can be a suitable alternative to this issue at the counter part. At present, the established EV chargers mostly utilizes the Si MOSFET technology, however, Silicon Carbide (SiC) based MOSFETs can further improve the power density of the converter with a compact sizing. Also, implementation of SiC MOSFETs on the single stage BDC converter can further enhance the efficiency. With this background, the main aim of the project is to design an improved topology of single stage high power density SiC MOSFET based EV chargers with a provision to AC – DC bidirectional power flow capability. The designed converter is intended to have higher efficiency ( more than 95%) and to maintain power factor (more than 0.9 ) considering lower THD (less than 5% as defined by IEC 61000-3-2). |