15 kV GTO Thyristor Module for Use in Small, Highly Efficient Current Source Inverters Utilizing AC-LinkTM Technology

Renewable energy resources are being adopted by government entities, utility power providers and more recently by industrial behind-the-meter end-users as well. Solar power is attractive especially in areas where electricity costs are high, such as California and New Jersey. New Jersey is interesting in that its solar insolation is mild compared to the rest of the country, yet it ranks 2nd in the implementation of solar power, only behind California. Private companies are adopting large solar farms to provide greater than 80% of their power due to the high cost of electricity in this region. For example, McGraw Hill and Shiseido, both located in East Windsor, NJ, have built 14 MW and 1.4 MW solar farms, respectively. The market represented by these types of forward thinking companies creates a working model for more wide scale adoption in the private sector as well as local municipalities to implement solar power in highly populated areas where solar insolation is low, but where transmission is minimized. The key to gaining more wide spread adoption of solar power is to lower the cost of not only solar modules, but ancillary equipment as well, i.e. power inverters and storage systems for intermediate scales (100kW-10MW). Currently, the cost of power inversion falls around $0.20 to $0.30 per watt depending on the scale of the deployment. The cost of power conversion is limited by the abilities of silicon switches to operate at higher voltages and faster frequencies. The impact of a medium voltage switch ( & gt; 15 kV) could greatly shrink the weight and cost of power converters by reducing cable size, transformer size, and eliminating forced convection cooling systems all together. To address topic 5b, USCi and Princeton Power Systems propose to fabricate a switch module that is rated at 15 kV, thus usable for switching voltages up to ~11 kV. Adopting a bipolar p-type SiC-GTO approach coupled with the AC-linkTM topology allows the device to switch in the medium voltage range while maintaining low losses and a high switching speed (~10 KHz). Switching at medium voltages allows the current to be reduced drastically by a factor of ~10, thus impacting every other component in the inverter. The proposed module will provide a significantly smaller, more efficient and lower cost solution for converters/inverters for utility scale smart grid and energy management applications. The proposal will outline USCis approach to realize a prototype (TRL 5) switch module where the epitaxial growth and device fabrication will be performed at USCis wafer fab in Princeton, NJ. Phase I will focus on the device and module designs, proof of 15 kV packaging fundamentals as well as the epitaxial growth. Phase II will involve device processing, module assembly and proof of performance. In addition, USCi will obtain critical application requirements by consulting with Princeton Power Systems, also located in Princeton and offer state-of-the-art commercial power conversion technology for PV systems.