The inevitable choice for the automotive industry to suppress greenhouse gas
emissions is zero-emission vehicles such as battery electric vehicles. Some of the
main barriers regarding the adoption of electric vehicles are range anxiety, and lack
of charging infrastructure, which can be addressed by ultra-fast chargers or charging
stations. The conventional ultra-fast chargers are low-voltage (LV) connected
through line-frequency transformers, which pose disadvantages such as low
efficiency, high cost, and large footprints. The medium-voltage (MV) connected
charging station is proposed by the researchers to overcome the challenges regarding
the conventional chargers by eliminating the line-frequency transformer and direct
connection to the medium voltage.
The most challenging part of the medium-voltage ultra-fast chargers is the
AC/DC stage connection to the medium voltage. Different medium-voltage
multilevel converters have been proposed to facilitate the direct connection to the
medium-voltage grid. However, disadvantages such as a high number of components
and control complexity weaken the strength of medium-voltage connected stations.
The main focus of this thesis is on novel advanced medium-voltage multilevel
topologies and control techniques for medium-voltage connected ultra-fast EV
charging applications. First, a novel controller based on SPWM is proposed to
control the flying capacitor voltages of a four-level T-type Nested Neutral Point
Clamped (NNPC) topology. Second, a new five-level T-type NNPC topology is
proposed that has a minimum number of components in comparison to other
existing five-level topologies. To extend the voltage and power rating, a novel seven-level
topology is proposed that has the lowest number of components in comparison
to other existing topologies. Moreover, three different controllers are developed to
control the voltages of the seven-level topology based on Model Predictive Control,
where the challenges regarding significant computational burden and weighting
factor elimination are addressed.
Finally, an MV-connected ultra-fast charging station architecture is proposed,
where the proposed seven-level topology is considered as the AC/DC stage.
Comparison of the proposed topology to the LV-connected stations shows that the
efficiency, cost, and power quality of the charging stations can be improved
significantly. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/26861 |
| Date | January 2021 |
| Creators | Bahrami, Ahoora |
| Contributors | Narimani, Mehdi, Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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