Switching characteristics of SiC JFET and Schottky diode in high-temperature dc-dc power converters
01 Jan 2005-IEICE Electronics Express (The Institute of Electronics, Information and Communication Engineers)-Vol. 2, Iss: 3, pp 97-102
TL;DR: The authors packaged SiC JFET and Schottky diodes in thermally stable packages and built a high-temperature inductor to demonstrate the suitability of the SiC devices for high-Temperature power converter applications.
Abstract: This paper reports on SiC devices operating in a dc-dc buck converter under extremely high ambient temperatures. To this end, the authors packaged SiC JFET and Schottky diodes in thermally stable packages and built a high-temperature inductor. The converter was tested at ambient temperatures up to 400°C. Although the conduction loss of the SiC JFET increases slightly with increasing temperatures, the SiC JFET and Schottky diode continue normal operation because their switching characteristics show minimal change with temperature. This work further demonstrates the suitability of the SiC devices for high-temperature power converter applications.
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TL;DR: In this article, a power converter operating at temperatures above 200 °C has been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).
Abstract: High temperature power electronics has become possible with the recent availability of silicon carbide devices. This material, as other wide-bandgap semiconductors, can operate at temperatures above 500 °C, whereas silicon is limited to 150-200 °C. Applications such as transportation or a deep oil and gas wells drilling can benefit. A few converters operating above 200 °C have been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).
293 citations
Cites background from "Switching characteristics of SiC JF..."
...One of the advantages of unipolar devices is their speed, offering very low commutation losses due to the lack of recovery phenomenon [9]....
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TL;DR: In this article, the authors developed a C -V characterization system for high-voltage power transistors (e.g., MOSFET, insulated gate bipolar transistor, and JFET), which realizes the selective measurement of a specified capacitance from among several capacitances integrated in one device.
Abstract: The switching behavior of semiconductor devices responds to charge/discharge phenomenon of terminal capacitance in the device. The differential capacitance in a semiconductor device varies with the applied voltage in accordance with the depleted region thickness. This study develops a C - V characterization system for high-voltage power transistors (e.g., MOSFET, insulated gate bipolar transistor, and JFET), which realizes the selective measurement of a specified capacitance from among several capacitances integrated in one device. Three capacitances between terminals are evaluated to specify device characteristics-the capacitance for gate-source, gate-drain, and drain-source. The input, output, and reverse transfer capacitance are also evaluated to assess the switching behavior of the power transistor in the circuit. Thus, this paper discusses the five specifications of a C -V characterization system and its measurement results. Moreover, the developed C -V characterization system enables measurement of the transistor capacitances from its blocking condition to the conducting condition with a varying gate bias voltage. The measured C -V characteristics show intricate changes in the low-bias-voltage region, which reflect the device structure. The monotonic capacitance change in the high-voltage region is attributable to the expansion of the depletion region in the drift region. These results help to understand the dynamic behavior of high-power devices during switching operation.
93 citations
TL;DR: Based on the detailed analysis of the losses in the converter, a model to theoretically calculate the efficiency of the converter was developed in this article, where the influences of temperature, switching frequency, duty cycle and material of switching device on the converter's efficiency were experimentally investigated.
60 citations
15 Jun 2008
TL;DR: In this article, an airborne high temperature inverter with a 200C cooling source and 4 kVA power is described. Butler et al. describe the laboratory step-by-step work towards a prototype and operate under full load (15A) using high precision shunt and voltage probes.
Abstract: SiC devices enable for high temperature operation of power converters. The paper describes the laboratory step by step work towards an airborne high temperature inverter : 200C cooling source, 4 kVA power. From 'JFET only' to 'full three phase power stage' tested up to 250C, including capacitor. Device samples are characterized in order to set the requirements for the gate driver and to evaluate maximum switchable power. Switching losses are measured using high precision shunt and voltage probes. A prototype is built and operation under full load (15A) is verified.
55 citations
Cites background from "Switching characteristics of SiC JF..."
...A 3-phase inverter is a suitable pilot converter to demonstrate high-temperature operation up to 200°C. Previous work has shown the feasability of inverters working at such temperatures using SiC JFETs as power switches, [2], [3], [4], [5], [6]....
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07 May 2007
TL;DR: In this paper, the feasibility of synchronous rectification for SiC MOSFET in dc-dc converter applications is discussed, and the SiC SBD is compared with the conventional Si MOSD in dc characteristics to the gate voltage for forward and backward direction.
Abstract: This paper shows the feasibility of synchronous rectification for SiC MOSFET in dc-dc converter applications. The SiC MOSFET is compared with the conventional Si MOSFET in dc characteristics to the gate voltage for forward and backward direction, at first. Then, their turn-on and turn-off switching characteristics are evaluated in single device operation. Finally, their operations in a practical circuit of dc-dc buck converter are experimented, and the feasibility of their operation in synchronous rectification are discussed. The body diode in SiC MOSFET shows less reverse recovery than the body diode in Si MOSFET. Then, SiC MOSFET gives superior performance in the synchronous rectification of high voltage dc-dc converter with fast switching. This paper also studies the effect of externally connected free-wheel SiC SBD in anti-parallel to MOSFET. The body diode of SiC MOSFET is comparable to the SiC SBD in the reverse recovery characteristics. The conduction loss in free-wheeling period can be reduced by the application of SiC SBD. They are confirmed in the dc characteristics and in the dc-dc buck converter operation.
44 citations
Cites background from "Switching characteristics of SiC JF..."
...The performance of bidirectional dc-dc converter depends on the device characteristics [10-15] and the conversion efficiency can be improved by synchronous rectification....
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References
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TL;DR: In this article, the authors derived new expressions for specific on-resistance in power semiconductor devices, such as heterojunction MOSFETs, using GaN and compared these new expressions to the previous literature.
Abstract: An advantage for some wide bandgap materials, that is often overlooked, is that the thermal coefficient of expansion (CTE) is better matched to the ceramics in use for packaging technology. It is shown that the optimal choice for uni-polar devices is clearly GaN. It is further shown that the future optimal choice for bipolar devices is C (diamond) owing to the large bandgap, high thermal conductivity, and large electron and hole mobilities. A new expression relating the critical electric field for breakdown in abrupt junctions to the material bandgap energy is derived and is further used to derive new expressions for specific on-resistance in power semiconductor devices. These new expressions are compared to the previous literature and the efficacy of specific power devices, such as heterojunction MOSFETs, using GaN are discussed.
477 citations
Additional excerpts
...Power Electron., vol. 18, no. 3, pp. 907–914, 2003....
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TL;DR: In this article, the electrical performance of silicon carbide (SiC) power diodes is evaluated and compared to that of commercially available silicon (Si) Diodes in the voltage range from 600 V through 5000 V.
Abstract: The electrical performance of silicon carbide (SiC) power diodes is evaluated and compared to that of commercially available silicon (Si) diodes in the voltage range from 600 V through 5000 V. The comparisons include the on-state characteristics, the reverse recovery characteristics, and power converter efficiency and electromagnetic interference (EMI). It is shown that a newly developed 1500-V SiC merged PiN Schottky (MPS) diode has significant performance advantages over Si diodes optimized for various voltages in the range of 600 V through 1500 V. It is also shown that a newly developed 5000 V SiC PiN diode has significant performance advantages over Si diodes optimized for various voltages in the range of 2000 V through 5000 V. In a test case power converter, replacing the best 600 V Si diodes available with the 1500 V SiC MPS diode results in an increase of power supply efficiency from 82% to 88% for switching at 186 kHz, and a reduction in EMI emissions.
178 citations
Additional excerpts
...Power Electron., vol. 18, no. 3, pp. 907–914, 2003....
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...[7] T. Funaki et al., “SiC JFET dc Characteristics Under Extremely High Ambient Temperatures,” IEICE Electron....
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...The authors acknowledge the SiC JFET devices supplied by Dr. P. Friedrichs (SiCED) and the experimental facilities by Dr. A. Lostetter (Arkansas Power Electronics International, Inc.)....
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...Power Electron., vol. 16, no. 2, pp. 273–280, 2001....
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...[2] M. Lades, “Modeling and Simulation of Wide Bandgap Semiconductor Devices: 4H/6H-SiC,” Selected Topics Electron....
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76 citations
"Switching characteristics of SiC JF..." refers background in this paper
...High-temperature operation requires not only the SiC bare dies be capable of operating at high temperatures, but also their packaging and the auxiliary components when used in an electric circuit like a dc-dc buck converter....
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50 citations
"Switching characteristics of SiC JF..." refers background in this paper
...High-temperature operation requires not only the SiC bare dies be capable of operating at high temperatures, but also their packaging and the auxiliary components when used in an electric circuit like a dc-dc buck converter....
[...]
TL;DR: The experimental results show that the device can operate at 450°C, which is impossible for conventional Si devices, but the current capability of the SiC JFET diminishes with rising temperatures, and the saturation current becomes 20% at450°C with respect to the value at the room temperature.
Abstract: This paper reports on the measured dc characteristics of a SiC JFET device from room temperature up to 450°C in order to evaluate the device's capability for high-temperature operation. The authors packaged SiC JFET bare die into a dedicated high-temperature package to be able to perform experiments under extremely high ambient temperatures. The experimental results show that the device can operate at 450°C, which is impossible for conventional Si devices, but the current capability of the SiC JFET diminishes with rising temperatures. For example, the saturation current becomes 20% at 450°C with respect to the value at the room temperature.
27 citations