Stacey Joy Kennerly

Overview of 1.2kV – 2.2kV SiC MOSFETs targeted for industrial power conversion applications

This paper presents the latest 1.2kV-2.2kV SiC MOSFETs designed to maximize SiC device benefits for high-power, medium voltage power conversion applications. 1.2kV, 1.7kV and 2.2kV devices with die size of 4.5mm × 4.5mm were fabricated, exhibiting room temperature on-resistances of 34mOhm, 39mOhm and 41mOhm, respectively. The ability to safely withstand single-pulse avalanche energies of over 17J/cm2 is demonstrated. Next, the 1.7kV SiC MOSFETs were used to fabricate half-bridge power modules. The module typical onresistance was 7mOhm at Tj=25°C and 11mOhm at 150°C. The module exhibits 9mJ turn-on and 14mJ turn-off losses at Vds=900V, Id=400A. Validation of GEs SiC MOSFET performance advantages was done through continuous buck-boost operation with three 1.7kV modules per phase leg exhibiting 99.4% efficiency. Device ruggedness and tolerance to terrestrial cosmic radiation was evaluated. Experimental results show that higher voltage devices (2.2kV and 3.3kV) are more susceptible to cosmic radiation, requiring up to 45% derating in order to achieve module failure rate of 100 FIT, while 1.2kV MOSFETs require only 25% derating to deliver similar FIT rate. Finally, the feasibility of medium voltage power conversion based on series connected 1.2kV SiC MOSFETs with body diode is demonstrated.

High performance SiC MOSFET module for industrial applications

A novel 1.7kV, 500A low inductance half-bridge module has been developed for fast-switching SiC devices. The module has a maximum temperature rating of 175°C. There are 12 GE SiC MOSFET chips per switch and the MOSFETs body diode is utilized as the freewheeling diode. The modules typical on-resistance is 3.8mOhms at 25°C and 5.8mOhms at 175°C. Internal loop inductance measured from DC input terminals is 4.5nH, approximately 75% lower than that of a standard IGBT module. When connected to a low inductance busbars, the module can be switched in 50ns without excessive voltage and current overshoots. Double pulse inductive switching losses at VDS=1000V, Id=450A and TJ=150°C are: EON=21.5mJ, EOFF=16.5mJ and EREC=6mJ. The losses are at least ten times lower when compared to a similarly rated IGBT module, highlighting the SiC advantage for higher switching frequency applications. Short circuit testing was performed, demonstrating good ruggedness albeit the need for a fast protection circuit.

Readiness of SiC MOSFETs for Aerospace and Industrial Applications

This paper highlights ongoing efforts to validate performance, reliability and robustness of GE SiC MOSFETs for Aerospace and Industrial applications. After summarizing ruggedness and reliability testing performed on 1.2kV MOSFETs, two application examples are highlighted. The first demonstrates the 1.2kV device performance in a prototype high frequency 75kW Aviation motor drive. The second highlights the experimental demonstration of a 99% efficient 1.0MW solar inverter using 1.7kV MOSFET modules in a two-level topology switching at 8kHz. Both applications illustrate that SiC advantage is not only in improved performance, but also in significant system cost savings through simplifications in topology, controls, cooling and filtering.

High Performance 1.2kV-2.5kV 4H-SiC MOSFETs with Excellent Process Capability and Robustness

In this paper, we show state of the art, low on-resistance, 25mW/1.2kV and 43mW/2.5kV SiC MOSFETs with excellent design robustness and process control such that the parametric spread of key device characteristics are approaching Si products. The impact of starting material variability on device performance is shown and design sensitivity curves are presented.

A Piezoelectrically-Actuated Valve for Modulation of Liquid at High Flow Rate Under High Pressure

A MEMS valve implementation is presented as part of a comprehensive liquid fuel modulation system that targets improved NOx emissions in gas turbines. The target metrics require fuel delivery at high flow rates (>10 ml/s) and bandwidths (>100 Hz) against high pressures (>75 psi). A prototype microvalve has been designed and fabricated with conventional micromachining techniques coupled with an off-the-shelf piezoelectric actuator. The device has dimensions of 40 mmtimes11 mmtimes2.5 mm. Test results demonstrate flow modulation of 15 ml/min at 20 psid and 50 Hz, when the applied sinusoidal voltage to the piezo actuator and therefore the orifice area modulated by the lever arm, was varied between 84 V to 120 V.

Thermal Analysis of a Microfluidic Preconcentrator for Portable Micro Gas Analysis Systems

Two key challenges to portable gas chromatography are reducing preconcentrator power consumption and accurate temperature control of adsorbent. This paper presents the results of thermal modeling performed to optimize a microfabricated preconcentrator based on a silicon microhotplate and utilizing Metal Organic Framework (MOF) adsorbents. From this modeling, two design changes are presented that reduce the power consumption by 1.5 W and reduce temperature variation across the microhotplate by 50%.© 2009 ASME