Current Control and Loss Estimation in a Medium Voltage Silicon-Carbide Power Converter

Kirkeby, Mathias ; Nielsen, Morten Rahr

4. term

Energy Engineering, Master

2022

2022-05-30

112 pages

Attention toward wide bandgap materials has increased in the last decades as the inherent advantages of the materials’ properties have been proven attractive in semiconductor devices used in power electronic systems. The goal of this thesis is to demonstrate closed loop current control in a 10 kV Silicon-Carbide MOSFET based half-bridge power converter. To mitigate the impact of switching noise on the current feedback signal, the sampling scheme proposed in [1], [2] has been implemented and tested with success. A single phase Proportional-Resonant current controller has been designed and implemented in a DSP control board, which is embedded into a single phase back-to-back experimental setup. The controller includes a dead time compensation algorithm based on a linear approximation made from measured values of the actual dead time voltage error present during the switching transients for various levels of load current. The successful implementation of the current controller has enabled the use of the experimental setup as a test platform that can be used to evaluate the performance of the power modules with regard to their losses and MOSFET die temperatures during operation. This has been experimentally tested for various loading points in terms of DC-link voltage, load current, and switching frequency. The results from the experimental tests have been compared to expected values, which have been derived from the conduction losses calculated from the on-state resistance, and the switching losses based on a double pulse test performed in [3].

SiC ; Current Control ; MOSFET ; Medium Voltage ; Loss Estimation

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