SiC MOSFET Switching Research Articles

A Self-Regulating Active Gate Driver for SiC MOSFET Switching Loss Optimization

A Self-Regulating Active Gate Driver for SiC MOSFET Switching Loss Optimization

Study on switching behavior of silicon carbide MOSFET by gate driver

Compared with IGBT, SiC MOSFET has improved frequency efficiency, outstanding reliability which not only can achieve energy saving and loss reduction, but also increase power density and other characteristics. SiC MOSFETs are faced with countless challenges in practice because of their superior switching speed. The gate driver was adjusted in this paper to investigate the switching behavior of silicon carbide MOSFET. The switching behavior of silicon carbide devices was first characterized by simulation software using a double- pulse test bench. Different parasitic inductances, resistances and additional parameters were found to have significant impacts on SiC MOSFET switching behavior. The results are analysed after combination and comparison.

An Electric Field Probe With High Immunity for SiC MOSFET Switching Voltage Measurement

Accurate measurement of switching voltage is the basis for evaluating the dynamic behavior of power devices. With the development of wide bandgap (WBG) devices, the high switching speed of the silicon carbide metal–oxide–semiconductor field-effect transistors (SiC MOSFETs) imposes high bandwidth and strong immunity requirements on the voltage probe. The electric field probe (EFP) based on the principle of electric field coupling has a naturally high bandwidth, which can be considered as a potential competitor. However, due to the noncontact suspended measurement method, the interference signal is easily coupled by the EFP and affects the measurement accuracy. Thus, this article proposes a high noise-immune structure for EFP to implement the measurement of SiC MOSFET switching voltage. The EFP is manufactured from the printed circuit board (PCB), which can provide a more accurate parameter design. Then, the shielded copper clad and via arrays structures are proposed, and the effectiveness of the shielding structure is verified by adding an interference source. Finally, through the double-pulse test, it is demonstrated that the performance of the proposed EFP is sufficient to measure the switching voltage of SiC MOSFETs.

A Comprehensive loss analysis of SiC-based DAB DC-DC converter for electric vehicle application

This paper presents loss analysis of SiC MOSFET based bidirectional DAB (Dual Active Bridge) DC-DC converter for EV application. This converter benefits the efficiency of the EV vehicle by reducing power loss and voltage drop across the converter. The DAB uses WBG (Wide-Bandgap) semiconductor devices such as SiC MOSFET to optimize the efficiency and extend soft-switching over whole operating range. The SiC MOSFET switching devices rated at 1200 V with different drain- source on-state resistance Rds(on) of 21 mΩ/32 mΩ is considered. Therefore, a reliable converter rated at 10 kW which works under normal operating condition at high-switching frequency of 100 kHz. The switching and conduction losses are taken under two different junction temperature such as 25 °C and 100 °C with various operating load current between 10 A to 40 A. Based on an analysis of SiC MOSFET based DAB attains 98.8% efficiency. The simulation results are taken as voltage and current waveforms at various points of converter are reported. This SiC based DAB converter would be used in next generation of V2G (Vehicle-to-Grid) and G2V (Grid-to-Vehicle) technology.

Gate-switching-stress test: Electrical parameter stability of SiC MOSFETs in switching operation

We present a new, simplified, pulsed-gate stress test approach to determine the electrical parameter stability of SiC MOSFETs under application-like conditions over a lifetime. By comparing the results to an application test under the same conditions, we demonstrate that our test procedure reflects most realistically worst-case, end-of-life parameter drifts that occur in typical SiC MOSFET switching applications.

SiC MOSFET switching – Lower losses without increased EMI – A technique to evaluate and achieve this goal

SiC MOSFET switching – Lower losses without increased EMI – A technique to evaluate and achieve this goal

Investigation on Ultralow Turn-off Losses Phenomenon for SiC MOSFETs With Improved Switching Model

Traditional SiC MOSFET switching models cannot predict the turn-off losses precisely in the condition of small driver resistance and small load current, because they have not considered a special case in which the SiC MOSFET closes its channel before the SiC diode turns into the freewheeling-state during turn-off transient. To solve this problem, this article presents an improved SiC MOSFET turn-off model that considers the special case. The parasitic elements of circuit and the nonlinear characteristics of SiC MOSFET are also included in the proposed model to improve its accuracy. Experimental results show that the improved model can predict the turn-off transient of SiC MOSFET precisely. Moreover, the investigation of turn-off behavior shows that SiC MOSFET can achieve ultralow turn-off loss in the special case, because the channel current of SiC MOSFET can fall to 0 before the drain-source voltage rises to a high value. Driver resistance and load current are the decisive factors of achieving the special case, and this article gives the criterion of them. Besides, further studies show that lower common-source inductance, larger drain-source capacitance of MOSFET, and larger capacitance of diode can help to achieve ultralow turn-off loss. Experiments are carried out and the experimental results verify the analysis results.

The Method of the SiC MOSFET Replacing the Si IGBT in the Traditional Power Electronics Converter without Redesigning the Main Circuit and the Driver Circuit

As a wide bandgap power electronics device, the SiC MOSFET has a lot of advantages over the traditional Si IGBT. Replacing the Si IGBT with the SiC MOSFET in the existing power electronics converter is an effective means to improve the performance and promote the upgrading of the traditional converter. Generally, in order to make full use of its advantages of the SiC MOSFET, the Si IGBT in the traditional power electronics circuit cannot be simply replaced by the SiC MOSFET, but the main circuit and the driver circuit need to be redesigned because the oscillation problem and the cross-talk problem caused by the parasitic parameter are very serious when the SiC MOSFET switches. However, considering the low cost and the short cycle requirement of the equipment development, it is often difficult to redesign the circuit hardware structure of all converters. In order to resolve this contradiction, a ferrite bead based method is proposed in this paper. Through this method, without redesigning the hardware structure of the main circuit and the driver circuit, the SiC MOSFET can be used to replace the Si-based power electronics device directly, and the loss of the converter can be reduced with small oscillation. Finally, the effectiveness of the proposed method is proved by experiments.

Design of a High Voltage Pulse Generator with Large Width Adjusting Range for Tumor Treatment

The unique biological effects stimulated by short pulsed electric field have many applications in tumor treatment, such as irreversible electroporation, electrochemotherapy, gene transfection and immune therapy. These biological effects require high voltage pulses with different pulse width in the range from nanoseconds to hundreds of microseconds. To fulfill this requirement, a compact high voltage pulse generator has been designed based on a switchable capacitor array and a SiC MOSFET switching array. The proposed pulse generator has one output channel with an adjustable pulse width from 100 ns to 100 µs, an amplitude range from 0 kV to 2 kV, a repetition rate less than 1.2 kHz and a voltage drop less than 5%. The mechanism of the stacked switches circuit was investigated, in connection with a switchable capacitor array. The introduction of a switchable capacitor array extends the pulse width from nanosecond scale and microsecond scale compared with other similar design methods. The pulse generator has been designed in simulation and implemented in experiment. The developed pulse generator provides a convenient and economical tool for the further studies of the unique biological effects stimulated by different pulsed electric fields for tumor treatment.

Toward an In-Depth Understanding of the Commutation Processes in a SiC MOSFET Switching Cell Including Parasitic Elements

This article provides in-depth insight into the commutation processes of high-speed SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s and investigates how they are influenced by various parasitic inductances. The switching dynamics of wide-bandgap power semiconductor devices are significantly larger compared to those of silicon devices. Therefore, the parasitic elements in the switching cell become increasingly important, as they limit the current and voltage slopes and cause oscillations. A thorough understanding of these effects is necessary for the design of highly efficient and integrated next-generation power electronic converters. However, the means of modeling hard-switched transitions, e.g., equivalent circuits, have not been adapted sufficiently compared to existing models on relatively slow-switching devices. This article presents the theory of commutation in high-speed semiconductor devices and outlines its key differences to traditional commutation models. These new insights are used to analyze the influence of parasitic inductances on the switching transitions. The theory is validated experimentally by double-pulse tests with variable parasitic inductances, performed on a test printed circuit board equipped with SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s. The results are in good agreement with the theoretical findings.

SiC-Based Bidirectional Multilevel High-Voltage Gain Switched-Capacitor Resonant Converter with Improved Efficiency

This paper presents the research results of the bidirectional multilevel resonant switched capacitor converter (MRSCC). The converter can achieve a high voltage ratio in multilevel topology, which limits the voltage stress on switches and is able to operate with high power efficiency. The converter can be applied as an interconnector between DC voltage systems used for various applications. This paper presents a method that significantly improves the efficiency of the MSRCC through topology modification. Furthermore, the feasibility of the converter was demonstrated with the use of SiC and Si MOSFET switches, together with suitable passive components. It was demonstrated that the proposed modification of the topology makes the converter very efficient in SiC-based ones and can significantly improve the efficiency of Si MOSFET converters. The series of test results of the SiC-based converter is a novel aspect presented in this paper and shows promising achievements of efficiency. The results were obtained from the laboratory setup of 5 kW and 0.5/2 kV MRSCC. To demonstrate the bidirectional operation of the converter, a back-to-back setup (0.5/2/0.5 kV) was used. It also demonstrates that such a high-voltage gain converter can be accurately tested with the use of laboratory equipment with a typical voltage range.

Impact of Power Module Parasitic Capacitances on Medium-Voltage SiC MOSFETs Switching Transients

Increased switching speeds of wide bandgap (WBG) semiconductors result in a significant magnitude of the displacement currents through power module parasitic capacitances that are inherent in packaging design. This is of increasing concern, particularly in case of newly emerging medium-voltage (MV) SiC MOSFETs since the magnitude of the displacement currents can be several order higher due to the fast switching transients and increased voltage magnitudes of the SiC MOSFETs compared to their Si counter parts. The severity intensifies when the magnitude of the displacement current becomes comparable to a significant fraction of SiC MOSFETs rated current, leading to the worsened impact on the converter electromagnetic interference (EMI) as well as performance in terms of switching losses. The key objective of this article is to provide a detail insight into the impact of the module parasitic capacitances on the SiC MOSFET switching dynamics and losses. To realize this, a well-defined approach to dissect the switching energy dissipation is proposed, based on which the detailed analysis and quantitative measurements of the module parasitic capacitance impact on terms of added switching energy losses, and common-mode currents are investigated using a custom-packaged 10-kV half-bridge SiC MOSFET power modules. The theoretical analysis and experimental results obtained from dynamic as well as static characterization reveal that the impact of the module parasitic capacitance on the switching energy dissipation is twofold and substantially adverse such that it cannot be overlooked considering its intended application in the high-power MV power electronic converters.

A Novel Active Gate Driver for Improving SiC MOSFET Switching Trajectory

The trend in power electronic applications is to reach higher power density and higher efficiency. Currently, the wide band-gap devices such as silicon carbide MOSFET (SiC MOSFET) are of great interest because they can work at higher switching frequency with low losses. The increase of the switching speed in power devices leads to high power density systems. However, this can generate problems such as overshoots, oscillations, additional losses, and electromagnetic interference (EMI). In this paper, a novel active gate driver (AGD) for improving the SiC MOSFET switching trajectory with high performance is presented. The AGD is an open-loop control system and its principle is based on gate energy decrease with a gate resistance increment during the Miller plateau effect on gate–source voltage. The proposed AGD has been designed and validated through experimental tests for high-frequency operation. Moreover, an EMI discussion and a performance analysis were realized for the AGD. The results show that the AGD can reduce the overshoots, oscillations, and losses without compromising the EMI. In addition, the AGD can control the turn-on and turn-off transitions separately, and it is suitable for working with asymmetrical supplies required by SiC MOSFETs.