A family of planar MOSFETs with voltage ratings from 900 V to 15 kV are demonstrated. This family of planar MOSFETs represents Cree’s next generation MOSFET design and process, in which we continue to refine and evolve device design and processing to further shrink die sizes and enhance device performance. At voltage ratings of 3.3 kV and above, the specific on-resistance of the MOSFETs is approaching the theoretical limit. MOSFET switching performance in a clamped inductive switching circuit for the full range of voltage ratings is also demonstrated. Finally, improved threshold voltage and body diode stability under long-term stresses are presented.

A high-efficiency, 2.3-MW, medium-voltage, three-level inverter utilizing 4.5-kV Si/SiC (silicon carbide) hybrid modules for wind energy applications is discussed. The inverter addresses recent trends in siting the inverter within the base of multimegawatt turbine towers. A simplified split, three-layer laminated bus structure that maintains low parasitic inductances is introduced along with a low-voltage, high-current test method for determining these inductances. Feed-thru bushings, edge fill methods, and other design features of the laminated bus structure provide voltage isolation that is consistent with the 10.4-kV module isolation levels. Inverter efficiency improvement is a result of the (essential) elimination of the reverse recovery charge present in 4.5-kV Si PIN diodes, which can produce a significant reduction in diode turn-off losses as well as insulated-gate bipolar transistor (IGBT) turn-on losses. The hybrid modules are supplied in industry-standard 140 mm × 130 mm and 190 mm × 130 mm packages to demonstrate direct module substitution into existing inverter designs. A focus on laminated bus/capacitor-bank/module subassembly level switching performance is presented.

This paper discusses recent trends in wind turbine electrical architecture resulting from utility interconnect and public siting requirements. These trends together with constant need to reduce the cost-of-energy place a premium on wind turbine inverter efficiency. This need is addressed by the use of a medium voltage, three-level inverter with 4HN structure silicon carbide barrier diode located in the clamping diode location. A comparison with a conventional silicon PIN clamping diode is covered in detail.