Analyzing and Testing of New Silicon Carbide Components for Down Hole Oil Applications
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- Institutt for elkraftteknikk 
High temperature power converter becomes possible due to the development of SiC power technology. The inherent properties of wide bandwidth, high breakdown electrical field and high thermal conductivity give commercially available SiC power devices up to 150℃ operational junction temperature. However, due to immature of the SiC technology, the laboratory verification tests have to be done for SiC technology based power converter design. In this thesis work, a bridge leg gate driver has been designed with 700 ns dead time and reliable 20 V and -5 V gate driver voltages for on and off state separately. Digital overcurrent protection has been implemented to protect SiC power module during DPT (Dual Pulse Test). The PCB (Power Circuit Board) was provided by SmartMotor AS. The initial laboratory tests contained significantly voltage and current oscillations and ringing. The reasons were diagnosed as the parasitic elements. An improved waveform has been achieved by adding damping gate resistor, which resulted in slow switching speed. Furthermore, the stray capacitance which was due to the parallel configuration of SiC MOSFETs slowed down the turn-off speed. The more significant slow-down influences were observed at smaller drain current conditions. To finalize clean switching voltage and current waveforms, a minimized parasitic elements configuration has to be first realized. But there was not enough time to arrange a new improved design. All the measurement results had been done on the un-optimized power converter configuration, but with improved measurement instruments. The thesis work had also implemented DPTs with different drain current levels under voltage 300 V and 500 V separately.