Characterization and Modeling of High-Switching-Speed Behavior of SiC Active Devices

In 2011, after many years of research and development SiC power MOSFETs became available in the commercial marketplace. This paper presents the results of Co60 total ionizing dose (TID) effects for the new high power-high current 24 A SiC devices irradiated at room temperature and 125°C. These commercially available components remained operational after a radiation dose of more than 100 krad. However, gamma ray irradiation gave rise to changes in current-voltage and capacitance-voltage characteristics. Specifically, threshold voltage decreased, resulting in increased current drive. We also observed rises in interface state densities, as well as input, output and reverse transfer capacitances with increasing accumulated doses.

Radiation Effects in Commercial 1200 V 24 A Silicon Carbide Power MOSFETs

An improved model of medium voltage (1200 V) silicon carbide (SiC) MOSFET based on PSpice is proposed in this paper, which is suitable for wide temperature range applications especially at low temperature. The static characteristics of SiC MOSFET are described by introducing temperature-dependent voltage source and current source. The effect of negative turn-off gate drive voltage is also taken into account in the modeling. In order to reflect the low-temperature characteristics of SiC MOSFET accurately, low temperature (-25 °C) measurements are carried out, which provide the modeling basis. The determinations of key parameters in the model are analyzed in detail, including the on-state resistor, internal gate resistor, temperature dependent sources, and some capacitors. The proposed model is verified by the experimental tests on a buck converter prototype at different input voltages, input currents, and temperatures. Simulation results on the proposed model coincide well with the experimental test results, in terms of switching waveforms and power losses even at low temperature (-25 °C). These results demonstrate that the proposed model exhibits high accuracy within wide temperature range.

Improved Modeling of Medium Voltage SiC MOSFET Within Wide Temperature Range

This paper presents two novel measurement methods to characterize silicon carbide (SiC) MOSFET devices. The resulting data are utilized to significantly improve the extraction of a custom device model that can now accurately reproduce device switching behavior. First, we consider the $I_{\text{d}}- V_{\text{ds}}$ output characteristics of power devices such as SiC transistors. These are typically measured using traditional curve tracers, but the characterization of the high-voltage and high-current (HVHC) region is very challenging because of device power compliance and self-heating. In this paper, we introduce a measurement technique that overcomes self-heating and derives the HVHC region from switching waveforms. The switching transient characteristics of devices are used to determine drain current $(I_{\text{d}})$ as a function of drain–source voltage $(V_{\text{ds}})$ in the HVHC range. Second, we consider another challenging characterization area: measurement of nonlinear capacitances when device is turned on. These capacitance characteristics of on-state devices are important for correcting disagreements between simulations and measurements in turn-off switching transient waveforms and cannot be measured using a conventional capacitance-voltage meter. We introduce S-parameter measurements as an effective method to obtain the capacitance characteristics of both off-state devices and on-state devices. These novel measurement techniques have been applied to the modeling of a SiC device. The extracted device model, a modified version of the popular Angelov−GaN high-electron-mobility transistor model, shows significant improvement in terms of the accuracy of switching waveforms of devices over a wide range of operating conditions.

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Measurement Methodology for Accurate Modeling of SiC MOSFET Switching Behavior Over Wide Voltage and Current Ranges

W kV SiC MOSFETs are currently under development by a number of organizations in the United States with the aim to enable their applications in high voltage high frequency power conversion applications. The aim of this study is to demonstrate their high frequency high temperature operation capability in the application of a DC/DC boost converter. A DC/DC boost converter based on a 10 kV 10 A SiC MOSFET and a 10 kV 5A Junction Barrier Schottky (JBS) diode is designed and tested for continuous conditions up to a switching frequency of 25 kHz, an output voltage of 4 kV, an output power of 4 kW and a junction temperature of 174degC for the SiC MOSFET. In the steady state of the 20 kHz boost converter operation, the input power is 4335 W, the output power is 4030 kW and the efficiency is 93%. The power loss analysis shows the total power loss in the 30.45 mm2 SiC MOSFET is 115 W, and the operating junction temperature of the SiC MOSFET is 140degC at the 20 kHz switching frequency. The power losses and the junction temperature of the SiC MOSFET as a function of the switching frequency, load current and input voltage in the boost converter are investigated extensively. The fast switching, low loss and high temperature operation capability of 10 kV SiC MOSFETs demonstrated in the DC/DC boost converter make them attractive in high frequency high voltage power conversion applications.

10 kV SiC MOSFET Based Boost Converter

This study deals with power MOSFET models Parasitic capacitances are one of the main parameters for dynamic models, and have a critical influence on switching waveforms and switching losses Most classical models consider that these capacitances are only mono-voltage dependent, but these models do not take into account the two (drain and gate) voltage influences on parasitic capacitances values, and consequently on switching behavior Therefore simulation results have not been properly estimated, especially for switching losses This aspect may appear critical for driver design or integration perspectives Moreover, manufacturers' datasheets offer a description of these capacitances out of nominal operation; this kind of data is not sufficient to build an accurate dynamic model of the component In this paper, we show the inadequacy of this kind of model, by referring to a physical structure analysis of charge locations during switching transitions Next, the article presents a new insight based on this approach Firstly, we describe the analytical equations ruling this model with respect to critical voltage changes After an experimental parameter extraction under nominal operation, our empirical model is established and implanted in the PSPICE simulator Its topology allows the modeling of both voltages-depending nonlinear capacitances to be taken into account The complete model is tested on components from various manufacturers, and results are compared with experimental curves This model appears to be more accurate and more reliable than PSPICE or manufacturer original models Consequently, this accuracy in switching waveforms is invaluable for driver design It improves switching losses and EMI predictions, and could be used for optimizing the design of drive circuit (eg in applications such as integrated functions) This aspect appears greatly valuable for manufacturers

Power MOSFET switching waveforms: an empirical model based on a physical analysis of charge locations

Main power switches such as metal oxide semiconductor field effect transistors or insulated gate bipolar transistors have reached very high performances from an electrical point of view. If their electrical characteristics are getting closer to physical limits, there is still a lot to do to improve their functionalities. The paper presents the monolithic integration of a gate drive power supply with the power switch to be driven. The operating principle is discussed to demonstrate that all needed components for this function can be integrated with the power switch. It is also demonstrated that the solution does not require any main power switch technological process modification-leading to a cost effective solution. Modeling and analysis comments are provided in order to clarify and to present operating principles and possible design constraints. Finally, the realization itself is presented. Prototypes are used to highlight the interest of such function.

Fully integrated gate drive supply Around Power switches

This study deals with power MOSFET models. Parasitic capacitors are one of the main parameters for dynamic models, and have a critical influence on switching waveforms and switching losses. Most of classical models consider that these capacitors are one-voltage dependent. The aim of this paper is to present a new insight based on a physical structure analysis of charge locations and moves and electrical waveforms, both during switching transitions. Establishment of the model with respect to critical voltage changes is presented, and results are compared with experimental curves. This model appears to be more accurate and more reliable than PSPICE or manufacturer original models.

Empirical power MOSFET modeling: practical characterization and simulation implantation

Nowadays MOSFET components are widely used in power converters. They are subjected to increasing requirements: electrical performances, integration, smaller volume and price. The integration process offers the possibility to reduce the price and the volume of these devices and in the same time to add some useful functionalities like sensors for protection and control. This paper presents a solution to integrate the gate driver supply. The main advantage is the energetic autonomy of these devices. This is a parallel circuit that will take the energy available across the power switch while it is in the off-state. This circuit contains a JFET and one storage capacitor. The triode-like JFET characteristics permit to use it like a regulator of the self-supply circuit. We present the possible integration of JFET with the main power switch (MOSFET). The two devices are integrated within the same die; they share the same voltage termination and follow the same technological process. The circuit analysis of the structure is provided using numerical simulations.

L. Aubard

Papers

Power MOSFET switching waveforms: an empirical model based on a physical analysis of charge locations

Fully integrated gate drive supply Around Power switches

Empirical power MOSFET modeling: practical characterization and simulation implantation

Integrated driver supply with JFET as a "linear" regulator