A master thesis from Aalborg University
Using a Variable Capacitor as a Voltage Actuator
Author(s)
Term
4. term
Education
Publication year
2024
Submitted on
2024-05-30
Pages
61 pages
Abstract
Gate drivers are a ubiquitous component in power electronics, and is therefore subject to much research. An fairly unexplored topic is using a variable capacitor as a gate driver. This project analyses and designs a variable capacitor for use as a gate driver. The idea is successfully tested using a basic plate capacitor, which is used to turn on a GaNFET by rapidly removing the dielectric material. This experiment, along with simulation studies give insight into a possible design. Using these insights, a variable capacitor is designed. The capacitor consists of two PCBs, with one being spun around an axis by a motor. This spinning causes the capacitance to change. The capacitance is measured using a voltage divider, and it is found to deviate slightly from expectations. The variable capacitor is inserted into an electrical circuit and it is found that a variable voltage can be achieved over a load similar to the gate of a FET. The predicted voltages do not correspond with many of the measured voltages. When the load is exchanged for a GaNFET, the variable capacitor can successfully regulate turn on and turn off. Instability is seen in the gate and drain voltages of the GaNFET. It is concluded that the variable capacitor can be used to regulate a voltage, but it is not suitable for use as a gate driver. To finish, some ideas are given for future work with this idea.
Gate drivers are a ubiquitous component in power electronics, and is therefore subject to much research. An fairly unexplored topic is using a variable capacitor as a gate driver. This project analyses and designs a variable capacitor for use as a gate driver. The idea is successfully tested using a basic plate capacitor, which is used to turn on a GaNFET by rapidly removing the dielectric material. This experiment, along with simulation studies give insight into a possible design. Using these insights, a variable capacitor is designed. The capacitor consists of two PCBs, with one being spun around an axis by a motor. This spinning causes the capacitance to change. The capacitance is measured using a voltage divider, and it is found to deviate slightly from expectations. The variable capacitor is inserted into an electrical circuit and it is found that a variable voltage can be achieved over a load similar to the gate of a FET. The predicted voltages do not correspond with many of the measured voltages. When the load is exchanged for a GaNFET, the variable capacitor can successfully regulate turn on and turn off. Instability is seen in the gate and drain voltages of the GaNFET. It is concluded that the variable capacitor can be used to regulate a voltage, but it is not suitable for use as a gate driver. To finish, some ideas are given for future work with this idea.
Documents
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