Projects per year
Abstract
Renewable energies have experienced a significant growth and importance in the
last two decades, of which energy from photovoltaic plants are a major contributor.
Since solar cells have low efficiencies themselves, however, the necessity of high efficiency
power converters at low cost and preferably low complexity leads to new
research demands. This is especially true in the field of low cost residential PV
inverters where efficiencies are used as major selling arguments. Traditional converter
topologies equipped with conventional Silicon based semiconductors to date
reach their limitations and new approaches are necessary. Therefore, research areas
typically focus on both new topologies and utilizing more advanced semiconductor
devices.
To this end, semiconductor devices made of Silicon Carbide have been gaining
increasing interest in the last two decades after the successful commercialization
of high voltage power diodes. By now, the performance potential of switching
devices made of Silicon Carbide is commonly accepted, though they have not found
commonplace usage within commercial converter systems for several reasons, among
others reliability, availability/cost and gate driver complexity. Therefore, more
complex Silicon based converters can be used instead to achieve lower semiconductor
losses.
While there is no absolute solution in which direction to go to achieve the aforementioned
design goals, this dissertation will thoroughly investigate two potential
approaches and discuss their trade-offs.
The contributions are:
• Comprehensive loss analysis and identification of major loss contributors within T-Type converter topology operating in inverter and rectifier context.
• Evaluation of the use and loss benefits of Silicon Carbide switching devices in the T-Type structure.
• Thorough investigation of the Hybrid-Neutral-Point-Clamped (Hybrid-NPC) topology as an alternative for the Silicon Carbide based T-Type converter.
• Alternative methodology of semiconductor loss model validation by experimental means. As to the advanced three-level T-Type converter topology, its unusual operation mode is thoroughly described identifying its limitations for high efficiency operation. With these results, the first approach utilizes low loss switching devices and their influence on the semiconductor loss behavior is analyzed. The results show that, for near unity power factor operation, a replacement of only two switching devices per phase leg can greatly reduce the semiconductor losses. The Hybrid-NPC converter can be seen as an attractive and cost competitive alternative to the Silicon Carbide based converter, also allowing to overcome the major drawbacks with the conventional Silicon IGBT based T-Type structure. Both alternatives are based on a semiconductor/topological level and thus this is where the loss reduction occurs. The difficulty in experimentally evaluating only the semiconductor losses within a converter operating context is addressed in this work by presenting an alternative measurement approach. Using known heat loads, and a careful calibration procedure on the device heat sink, analytically obtained semiconductor loss models based on datasheet information and in-circuit switching transitions measurements can be experimentally verified and thus a fair performance comparison between two approaches is enabled.
• Comprehensive loss analysis and identification of major loss contributors within T-Type converter topology operating in inverter and rectifier context.
• Evaluation of the use and loss benefits of Silicon Carbide switching devices in the T-Type structure.
• Thorough investigation of the Hybrid-Neutral-Point-Clamped (Hybrid-NPC) topology as an alternative for the Silicon Carbide based T-Type converter.
• Alternative methodology of semiconductor loss model validation by experimental means. As to the advanced three-level T-Type converter topology, its unusual operation mode is thoroughly described identifying its limitations for high efficiency operation. With these results, the first approach utilizes low loss switching devices and their influence on the semiconductor loss behavior is analyzed. The results show that, for near unity power factor operation, a replacement of only two switching devices per phase leg can greatly reduce the semiconductor losses. The Hybrid-NPC converter can be seen as an attractive and cost competitive alternative to the Silicon Carbide based converter, also allowing to overcome the major drawbacks with the conventional Silicon IGBT based T-Type structure. Both alternatives are based on a semiconductor/topological level and thus this is where the loss reduction occurs. The difficulty in experimentally evaluating only the semiconductor losses within a converter operating context is addressed in this work by presenting an alternative measurement approach. Using known heat loads, and a careful calibration procedure on the device heat sink, analytically obtained semiconductor loss models based on datasheet information and in-circuit switching transitions measurements can be experimentally verified and thus a fair performance comparison between two approaches is enabled.
Original language | English |
---|
Place of Publication | Lyngby |
---|---|
Publisher | Technical University of Denmark, Department of Electrical Engineering |
Number of pages | 174 |
Publication status | Published - 2015 |
Fingerprint
Dive into the research topics of 'Advances in PV Inverters'. Together they form a unique fingerprint.Projects
- 1 Finished
-
PV Inverter and control
Anthon, A. (PhD Student), Andersen, M. A. E. (Main Supervisor), Knott, A. (Examiner), Nee, H.-P. (Examiner), Lomonova, E. A. (Examiner) & Zhang, Z. (Supervisor)
Technical University of Denmark
01/11/2012 → 20/01/2016
Project: PhD