Faster charging and availability of charging infrastructure are the two main challenges
facing an accelerated transition to sustainable electri ed transportation. Both challenges
can be solved by developing modular charging systems that are future proof
all while having low running and installation costs. As such, this thesis focuses on
developing modular and e cient DC/DC charging solutions with a wide charging
voltage range capability to meet the needs of existing and next generation plug-in
electric vehicles.
The thesis starts with describing its motivation and gives an overview on the
impact of charging technologies on the electri fication movement. Then, specifi c objectives
and research contributions are laid out to narrow the focus of the reader.
A review on existing charging systems, standards, architecture and features is presented.
Existing isolated and on-isolated power converter topologies for DC-chargers
are analyzed and research gaps in power converters with a wide charging voltage range
are highlighted.
A new single stage DC/DC converter topology and operation scheme is proposed
to extend the charging voltage range. Modeling and analysis of the proposed solution
was used to select the transition point between different operating modes. Impedance
tolerance and pulse distortion was modeled to analyze the passive current sharing error at light and full load operation. The combination of the proposed topology and
unique operating scheme reduced the voltage and current stress per device allowing
the use of lower kVA rated devices leading to higher cost savings compared to other
solutions. An experimental setup has been developed which showed the excellent
performance of the proposed topology.
The design and optimization strategy for the proposed dual-secondary dual-active
bridge (DAB) converter topology is presented. A converter loss model is developed
to take in to account: magnetic, switching, and conduction loss. Then, the design
process and quantization scheme to quantize charging pro les into discrete energy
points is explained, which entails parametric optimization using a genetic algorithm
(GA) to minimize energy loss across widely varying charging pro les based on actual
charging data. Comprehensive experimental testing was carried out to validate the
proposed design strategy and excellent performance was achieved over an extended
operating range.
After the review of power magnetics used in isolated chargers, high parasitic capacitance
in planar transformers was identi ed as an obstacle in the way of development
of chargers, especially in charging applications that demand high switching
frequencies or extended low power operation. Therefore, a novel planar transformer
structure was proposed with ultra-low winding capacitance. The proposed co-planar
transformer was compared to three other planar types to highlight the differences and
bene fits. Four different prototypes of planar transformers were built with the same
target speci fications, to compare the proposed structure against previous solutions.
Impedance testing of the planar prototypes was carried to measure the winding stray capacitance and frequency response. Experimental power testing using a DAB converter
setup showed excellent results in reducing voltage overshoot, high frequency
oscillations, and power losses.
Finally, a 30-kW dual-secondary DAB charging module was designed, implemented,
and tested. The purpose of this work is to bridge the engineering gap between
a proof of concept and a higher Technology Readiness Level (TRL) mature charging
module, focusing more on regulatory standards and control system development.
Experimental validation of the liquid cooled module showed excellent performance
characteristics. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/29429 |
| Date | January 2024 |
| Creators | Zayed, Omar |
| Contributors | Narimani, Mehdi, Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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