Dissertation
STEP-UP MODULAR MULTILEVEL CONVERTERS FOR ENERGY HARVESTING FROM LOW-VOLTAGE ENERGY RESOURCES
Doctor of Philosophy (PhD), Washington State University
01/2018
Handle:
https://hdl.handle.net/2376/111817
Abstract
A modular multilevel converter (MMC) has a modular design and features low harmonic
distortion and switching frequency. An MMC can be switched using staircase modulation
method (which has a low switching frequency) or the common pulse-width modulation
PWM method (which has a better harmonic performance). There are two main types of
MMCs: 1) MMC with half-bridge submodules, which has an output voltage with a peakto-
peak magnitude limited to its DC link voltage and 2) MMC with full-bridge submodules,
which has voltage boosting (step-up) capability.
This work proposes a step-up MMC with reduced number of switches in its submodules
(reduced-switch submodule: RSSM) for energy harvesting from low-voltage resources. This
work rst proposes the following methods and strategies for this MMC-RSSM with staircase
modulation for an arbitrary number of submodules: 1) an analytical method to study
dierent operating modes of MMC-RSSM, 2) a generalized switching strategy to synthesize
the output AC voltage and regulate the voltages of capacitors in all operating modes, and
3) an algorithm to improve the transient response of the MMC during start-up or transition
between operating modes. For applications with bidirectional power transfer, the RSSMs
should be replaced by full-bridge submodules to allow both positive and negative arm currents.
In this work, the proposed switching strategy (which focuses on energy harvesting
systems with a unidirectional power transfer) is then extended to bidirectional MMC-FBSMs.
This work also proposes a low-switching frequency PWM-based switching strategy for the
MMC-RSSM. This PWM-based switching strategy provides a continuous control over capacitor
voltages and a higher voltage boost without a signicant increase in switching frequency.
Simulation and experimental results validate the proposed topology, analysis, and switching
strategy.
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Details
- Title
- STEP-UP MODULAR MULTILEVEL CONVERTERS FOR ENERGY HARVESTING FROM LOW-VOLTAGE ENERGY RESOURCES
- Creators
- Younes Sangsefidi
- Contributors
- Ali Mehrizi-Sani (Advisor)Cheng-ching Liu (Committee Member)Vaithianathan Venkatasubramanian (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Electrical Engineering and Computer Science, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 92
- Identifiers
- 99900581714601842
- Language
- English
- Resource Type
- Dissertation