Papers by Keyword: Power Device

Abstract: The necessary condition for power devices with enough blocking properties is Junction termination technology. In this paper, starting with the dose of rings, 3.3 kV Floating Filed Rings was investigated, and the influence of electric field and current density on the breakdown characteristic is also described. The results show that the dose of field rings directly affects the stability of breakdown voltage, this impact is relevant to the location of the peak electric field and the peak current density when breakdown was occurred. When the peak electric field appears in the middle of the field rings, the breakdown voltage is not sensitive to the dose of rings; however, when the peak electric field and strongest current density appeared on the edge of termination at the same time, breakdown voltage become very sensitive to the dose of rings because of the highest impact ionization in this position. Simulations and experiments indicate that the junction termination has better withstand voltage stability , when electric field distributes uniformly, the position of breakdown is in the middle of the termination, and the strongest current density appears in the main junction.

Abstract: Power converter with full closed loop water cooling system, works not only use water cooling characteristics of high efficiency, but also the electricity, and reducing the volume to prevent contamination. In this paper, we proposed a novel p-cycle safety protection approach that can provide rapid cycling radiating, and can restore the status of power device. For power cabinet composition, IGBT power modules and reactors is primarary radiating components, in which IGBT power modules that used for water cooling solution is modeled as the cooled automobile engine cooling system using cycling design principle. Besides, machine side and the network side of the power module is installed in separate cabinet to improve the tightness of the entire cabinet, in order to resist sandstorms.

Abstract: The paper gives a systemic classification to the common electric vehicle (EV). The technology of low power converter using as auxiliary power supply and high power converter using for traction system has been deeply discussed from the view of topology, control strategy and devices. Finally, the development tendency of on board DC conversion technology is prospected.

Abstract: Power MOSFET device driven by voltage is designed as a power switching device in large capacity power supply system. It is also widely used in converters and motor controllers. However, the on-resistance characteristic during the increase of breakdown voltage is a problem. The on-resistance of super junction power MOSFET is lower by 1/3 than existing planar power MOSFET on 600V basis. This study designed 600V planar MOSFET/super junction MOSFET and compared their operation characteristics for lower on-resistance and higher breakdown voltage. The result suggested that super junction power MOSFET is better than planar power MOSFET by having 40% better on-state voltage drop performance.

Abstract: Silicon carbide (SiC) is one of the most attractive semiconductors for high voltage applications. The breakdown voltage of SiC-based devices highly depends on the variation of the fabrication process including doping of the epilayers and the etching steps. In this paper, we show a way to diminish this variability by employing novel trench structures. The influence of the process variations in terms of doping concentration and etching has been studied and compared with conventional devices. The breakdown voltage variation (ΔVBR) of 450 V and 2100 V is obtained for the ±20% variation of doping concentration of the devices with and without the trench structures, respectively. For ±20% variation in etching steps, the maximum ΔVBR of 380 V is obtained for the device with trench structures in comparison to 1800 V for the conventional structure without trench structures. These results show that the breakdown voltage variation is significantly reduced by utilizing the proposed structure.

Abstract: A new SiC power module package structure is proposed that is capable of withstanding greater ΔTj cycle stress. Its most notable feature is the use of a SiN substrate having Cu/Invar/Cu foils (C/I/C thickness ratio of 1/8/1) brazed on both sides as conductor plates. The CIC foils show a very low coefficient of thermal expansion (CTE) of 5.1 ppm/°C and therefore can significantly reduce package degradation resulting from the larger CTE mismatch of the conductor to SiC and SiN. A thermal cycle test (TCT) was conducted between -40°C and 250°C (ΔTj = 290°C). It was found that the SiC/Au-Ge/CIC-SiN die attachment maintained joint strength of 78 MPa even after 3000 cycles.

Abstract: We report on switch-on of 12 kV, 1cm2 optically triggered 4H-SiC thyristor fabricated by CREE Inc., to Imax=270 А with current rise time of ~ 3 s. Temperature dependence of holding current Ih in this thyristor has been experimentally studied in the temperature range from 300 to 425 K. It is shown that measurements of Ih temperature dependence under condition of optical switch-on at small anode bias and large load resistance reveal the existence of a ”weak point” within the optical window. This point is characterized by a much smaller critical charge than that within the remaining part of the window.

Abstract: The steady state characteristics of a normally-off 4H-SiC Bipolar Mode FET (BMFET) with a low on-resistance are investigated in a wide range of currents and temperatures by means of an intensive numerical simulation study which clarifies what are the main design constraints. Specific physical models and parameters strictly related to the presently available 4H-SiC technology are carefully taken into account. A drain forward current density up to 500 A/cm², a specific on-resistance lower than 2 mΩ∙cm² and a current gain in the order of a few tens are calculated. The blocking voltage is in excess of 1.3 kV with a low leakage current. These results are compared with the experimental data measured in the same test conditions of another SiC power device already introduced to the market.

Abstract: This paper introduced a new modular multi-level converter (MMC), which could enhance the voltage and power level by sub-converter modules in series and was easy to extend to any level of output. Its structure and working mechanism were described.By analyzing the new modular multi-level converter (MMC) working mode, its sub-module four power devices’ current distribution is detailed analysis. It can further guide the choice of the device. The simulation results show that the analysis is correct and effective. It can provide a valid theoretical basis for the choice of the MMC sub-module power devices.

Abstract: SiC Schottky barrier diodes were fabricated and measured properties were characterized by device simulation. Most of devices show low leakage current, however, a few devices show leakage current larger than the values estimated from deviation of drift layer parameters. The leakage current component remarkable in lower voltage and saturating at higher voltage is related to Schottky barrier tunneling at macroscopic defects. The component remarkable in higher voltage is considered to be due to microscopic defect related generation current, concerning with non-stoichiometry.