High power converters are widely used in many industries. At power levels in the
range of Mega Watt (MW), power conversion at medium voltage (MV) is preferred
due to better efficiency and lower cost. For medium voltages applications,
multilevel converters are widely adopted due to the features they offer with respect
to two-level converters. Cascaded H-bridge topology is a widely adopted multilevel
topology because of its modularity, scalability, and reliability. The conventional
cascaded H-bridge topology allows two-quadrant operation. In order to allow fourquadrant
operation, an active front end version of the cascaded H-bridge topology
has been proposed in literature and recently commercialized.
In the field, power converters operates under harsh loading and
environmental conditions. The resulting stresses imposed on converter components
cause their gradual degradation. In cascaded H-bridge converters, typically power
cell components such as power modules, DC-bus capacitors, and control PCBs are
v
highly stressed. Under these stresses power cell components degrade and require
replacement in the field, otherwise unexpected failures may occur.
The thesis aim is to address power cell components reliability through
proposing novel regenerative cascaded H-bridge converter control schemes to reduce
components stresses and failure probability without increasing size, cost, or
complexity. First, a novel PWM active front end control scheme has been proposed
to reduce the inherent ripple current stresses on the DC-bus capacitors. Second,
the thesis proposes a novel grid or near grid switching frequency front end control
scheme to reduce stresses on power modules and the power cell cooling
requirements. Third, novel cascaded H-bridge front end control schemes are
proposed to reduce the sensor count, thereby decreasing failure rate and cutting
down cost. The proposed work has been thoroughly validated through detailed 9-
cell regenerative cascaded H-bridge system simulation and experimentation. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/26907 |
| Date | January 2021 |
| Creators | Abuelnaga, Ahmed |
| Contributors | Narimani, Mehdi, Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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