Investigation on filter requirements and stability effects of SiC MOSFET-based high-frequency grid-connected converters

The new era of power semiconductor devices is exploiting the high potential of wide bandgap device-based high-frequency power converters. The advanced capabilities of Silicon carbide (SiC) semiconductors allow the power converters to switch at higher switching frequencies with lower switching and conduction losses. Operation under higher switching frequencies can drastically reduce the output filter requirements in grid-connected converters. At higher frequencies, an L-type filter can sufficiently eliminate the switching frequency harmonics. This will reduce the size and cost of the filter, which eventually results in the optimised system cost. In this paper, the filter requirements of SiC based high-frequency converters are investigated. Usage of LCL filters to remove high-frequency harmonic will shift the resonance frequency to high-frequency region, where these harmonics can create electromagnetic compatibility issues. In industries, passive damping is utilised for mitigating these oscillations. This will result in additional losses and compromise the advantages of SiC devices. Even though active damping can be utilised to eliminate resonance oscillations, the high bandwidth processors and measurement devices may increase the cost further. Simulation study is conducted on PSCAD/MATLAB and the experimental verification using Cree SiC devices verify the filter requirements, stability issues, and possible mitigating solutions for high-frequency grid converters.