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- Velander, Erik, 1980-
(författare)
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On Gate Drivers for MOS-Controlled Power Devices and dv-dt Filters for Train Traction Converters
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, low-loss gate-drive solutions and a proposed dv/dt-filter have been investigated with focus on train traction converters with dv/dt constraints.By using the silicon carbide (SiC) junction field-effect transistor (JFET), the switching losses can be significantly reduced compared to the commonly used insulated-gate bipolar transistor (IGBT), but complex gate-driver solutions are required for high utilization in terms of loss reduction.For the IGBT and the p-i-n diode, the dv/dt across the diode at the turn-ON process of the IGBT was found to be as highest with low phase current and low temperature while the losses are as highest at high phase currents and temperatures. Therefore, a proposal meeting this tradeoff has been addressed in this thesis tailored at minimal cost for the new half-bridge package resulting in a switching loss reduction of up to 30 %.For the SiC metal oxide semiconductor field effect transistor (MOSFET), an investigation has been performed in order to use the train operation point in order to minimize the switching losses given a certain dv/dt requirement. In addition, separate control of the di/dt and dv/dt were implemented. In total, a loss reduction of 20 % is achieved. In addition, phase short-circuit investigations have been performed using the SiC MOSFET with a gate-driver proposal meeting the application requirements. The results show that short circuits with fast current rise can be terminated.Finally, a new dv/dt filter which uses the stray inductance present in the inter-connections between the power devices and the convert output terminals as a filter component is proposed. By doing so, the SiC MOSFETs can be fully utilized with high dv/dt and low switching losses even though the converter output dv/dt levels are in the range of the levels for which an IGBT equipped converter exhibits with ultra-low additional filter losses. As a consequence, the switching frequency can be four times higher for the same switching losses.
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