Development of a boost converter for PV systems based on SiC BJTs

In the past years new power switching devices based on wide bandgap materials like silicon carbide (SiC) were more and more coming up, promising more efficient, smaller and lighter converter circuits. This paper demonstrates the advantages of the SiC bipolar junction transistor (BJT) by the realisation of a boost converter stage for photovoltaic (PV) systems. First the key attributes (on-state behaviour and switching losses) of the devices are reviewed. By this measurements, the driving circuits in the boost converter are optimized in order to achieve high efficiency. The application of SiC BJTs in a high efficient 5 kW boost converter stage for PV systems (300 V → 800 V) is demonstrated and the results are compared to the results obtained with the application of common silicon (Si) IGBTs.