SiC-based inverter could cut greenhouse emissions
Cree and the Kansai Electric Power Company (KEPCO) claim to have made a three-phase power inverter based on SiC chips with a record output of 100 kVA.
The figure is almost an order of magnitude higher than the collaboration s previous best, a 12 kVA module it developed two years ago.
The Durham, NC, chip manufacturer has been working on the inverter project for the past eight years along with KEPCO, which runs more than 160 power plants in Japan, including nuclear power stations.
Under the collaboration, Cree provides power chips including PiN diodes and thyristors, while KEPCO constructs the inverter modules.
Current inverter modules, which are largely based on silicon devices, are used to convert power from AC to DC, or to alter the operating frequency of motor drives. For example, they are used to transfer power from DC-based sources such as solar panels, batteries or wind farms, onto the AC grid.
However, the silicon-based modules are relatively inefficient, says KEPCO's SiC program manager Yoshitaka Sugawara: "A tremendous amount of energy savings could be realized by switching to SiC inverters because the power loss is estimated to be reduced by over 50%."
"Kansai plans on further increasing the power capability of these inverters in order to apply them to a variety of power systems," added Sugawara.
The key switching module in the 100 kVA inverter module consists of two different SiC devices "“ one commutated gate turn-off thyristor, an 8mm x 8mm square device, and one 6mm x 6mm PiN diode.
The 100 kVA inverter features six of these modules and does not require a so-called snubber circuit , used commonly to protect similar silicon-based thyristors.
John Palmour, Cree's executive VP of advanced devices, said that the progress that had been made in material development, including a reduction in the defect density of SiC crystals and improved epitaxy, was crucial to the breakthrough. However, he added that more development will be required before power utilities would begin to use SiC inverters.
If those improvements do result in widespread commercial deployment, it could contribute to a reduction in greenhouse gas emissions through more efficient power transfer through the grid.