Thomas E. Salem

Evaluation of a 1200-V, 800-A All-SiC Dual Module

Enhanced material properties of silicon carbide (SiC) offer improved performance capabilities for power electronic devices compared to traditional silicon (Si) components. This paper reports on the experimental characterization of a 1200-V, 800-A all-SiC dual power module that incorporates twenty 80-A SiC MOSFETs and twenty 50-A SiC junction barrier Schottky diodes. Forward and reverse conduction characteristics were measured at multiple gate voltages, current sharing was examined between the MOSFETs, and switching energies were calculated for various currents. Additionally, this module has operated in a full-bridge circuit with a peak loading of 900 Adc, a 600 Vdc bus, and a junction temperatures of 153°C. From the experimental data, a model of the module was created and used in a dc-ac inverter simulation study to demonstrate the possible benefits of SiC compared to Si technology. The use of an all-SiC module was shown to reduce inverter losses by 40% or more for most operating conditions. Furthermore, for similar output current levels, the all-SiC module can operate at switching frequencies four times higher than that of the Si module. This advanced dual power module demonstrates the ability to produce a high-current high-power switch using SiC technology.

High-Temperature High-Power Operation of a 100 A SiC DMOSFET Module

The development of Silicon-Carbide (SiC) power electronic devices having high operating temperatures, high breakdown voltages and low losses has been widely researched over the past few decades. While devices such as the SiC junction barrier Schottky (JBS) rectifier are becoming available in the commercial marketplace, the SiC DMOSFET is less mature. Although continued research on material processing and device-level structures is necessary for optimization, new high performance 50 A SiC DMOSFETs have been fabricated. These MOSFETs have been identified as candidates to replace Si IGBTs in high-current high-temperature power modules for large hybrid electric vehicle propulsion systems. This paper reports on the performance of a 100 A SiC module comprised of two 50 A DMOSFETs. Experimental results are presented for the module in a DC-DC boost converter operated with external 75 A SiC JBS diodes at 17 kW output while using 90 °C liquid coolant.

Nanocrystalline material development for high-power inductors

A new high-saturation induction, high-temperature nanocomposite alloy for high-power inductors is discussed. This material has FeCo with an A2 or B2 structure embedded in an amorphous matrix. An alloy of composition Fe56Co24Nb4B13Si2Cu1 was cast into a 1.10in. wide, 0.001in. thick ribbon from which a toroidal core of approximately 4.25in. outer diameter, 1.38in. inner diameter, and 1.10in. tall was wound. The core was given a 2T transverse magnetic field anneal, and impregnated for strength. Field annealing resulted in a linear B-H response with a relative permeability of 1400 that remained constant up to field strengths of 1.2T. The core was used to construct a 25μH inductor for a 25kW dc-dc converter. The inductor was rated for operation in discontinuous conduction mode at a peak current of 300A and a switching frequency of up to 20kHz. Compared to commercially available materials, this new alloy can operate at higher flux densities and higher temperatures, thus reducing the overall size of the inductor.

Validation of Infrared Camera Thermal Measurements on High-Voltage Power Electronic Components

Thermal performance of power electronic components Is a limiting factor on the power density and design of high-voltage, high-power systems. Therefore, accurate assessment and characterization of the thermal capabilities of these components is critical for the development and design of high-density power applications. This paper demonstrates the efficacy of using an infrared camera system to characterize high-voltage power electronic components. A comparison is given for the use of two different spray coatings to create a uniform surface emissivity within a variety of experimental situations.

1000-H Evaluation of a 1200-V, 880-A All-SiC Dual Module

The commercial availability of silicon-carbide (SiC) power devices began over a decade ago with the introduction of SiC diodes and has expanded in complexity the past few years to include the offering of SiC transistors and power modules. Recently, characterization of a 1200-V, 800-A all-SiC dual module designed for large-scale electric military vehicle applications has been reported. This paper expands on the previous work by presenting details and results obtained from a long-term evaluation of a similar module. The module has successfully operated in an experimental circuit at a switching frequency of 10 kHz while running vehicle load profiles for over 1000 h and exhibited little change in device characteristics. Of all measured characteristics, none had a significant unfavorable change greater than 10% from its initial value. The 1000 h of circuit operation represents 11 783 miles of use or over half of the expected lifecycle in a military vehicle traction inverter.

Design Considerations for High Power Inductors in DC-DC Converters

The demand for high density power conversion systems has led to numerous material developments for passive circuit components. Typically, these innovations improve thermal capabilities, enable higher switching frequencies, and increase component efficiency. For inductors, research has focused on formulating low-loss core materials such as distributed gap and nanocrystalline alloy materials that can be manufactured in appropriate core geometries. This paper presents a discussion of design trade-offs for core and winding implementations using these materials. Empirical results for power loss as well as temperature rise based on thermal management are presented for both distributed gap and nanocyrstalline alloy cores used in a high power DC-DC converter.

Calibration of an Infrared Camera for Thermal Characterization of High Voltage Power Electronic Components

Thermal performance of power electronic components is a limiting factor on the power density and design of high voltage high power systems. Therefore, accurate assessment and characterization on the thermal capabilities of these components is critical for the development and design of high density power applications. This paper presents a methodology for calibrating an infrared camera system for use in characterizing high voltage power electronic components

Reverse conduction of a 100 A SiC DMOSFET module in high-power applications

Numerous research efforts over the past few years have documented the enhanced capabilities that Silicon Carbide (SiC) offers over Silicon based power electronic devices. Additional research work has led to vast improvements in the manufacturing of SiC based components. As a result, SiC power electronic components, primarily diodes, are now readily available and this technology promises to have widespread market impact as more complex device structures are commercially realized. Recently, the development of a 1200 V 50 A SiC DMOSFET device and its use in a 100 A power module has been documented [1]. This paper extends that research work to report on the reverse conduction characteristics of the SiC DMOSFET and the system-level benefits for high-power applications that can be achieved by operating these devices in this manner. Experimental data is presented on the 100 A module consisting of two, 50 A SiC DMOSFETs and two, 50 A SiC JBS anti-parallel free-wheeling diodes used in a high-power bi-directional DC-DC converter during buck mode operation.

Application study of the benefits for using silicon-carbide versus silicon in power modules

On a device-level, the benefits of Silicon-Carbide (SiC) versus Silicon (Si) power components have been documented over the past several years [1-5]. The fabrication process for SiC components continues to mature and SiC products are now commercially available. The development of high-current MOSFETs and their use in all-SiC power modules have been reported [6-9]. Recently, the experimental characterization and performance of a 1200-V, 800-A all-SiC dual module has been documented [10,11]. This paper outlines the development of a simulation model for the 800-A all-SiC dual module from this experimental characterization data. Using this model, a comparison study is presented for using an all-SiC module versus an Si IGBT module in DC-DC and DC-AC power circuit applications at a 900-A, 600-A, and 300-A module level. Upgrading the power module from Si to SiC devices resulted in lower loss in nearly every simulated scenario.

Thermal performance of water-cooled heat sinks: a comparison of two different designs

As power electronic applications continue to switch higher levels of voltage and current in smaller-sized component packages, the resulting increase in power density requires efficient thermal management. This paper compares the thermal performance for operating a MOSFET on a water-cooled pole-arrayed heat sink versus a novel water-cooled microchannel heat sink. Details are presented on an innovative technique for determining the thermal capacitance modeling parameter for the heat sinks from experimental data.