Materials Science Forum Vol. 924

Abstract: A high-reliability auxiliary power supply (APS) for gate drive circuits is crucial to utilization of emerging medium voltage (MV ≥ 10 kV) Silicon Carbide (SiC) devices in high voltage applications. This paper proposes an active voltage divider based APS with lower arm voltage regulation. The proposed APS circuit is targeting the application of MV SiC devices in modular multilevel converters (MMCs). It can harvest energy from a MV (≥ 7 kV) dc bus to provide an isolated low voltage output to gate drive circuits of MV SiC devices. Compared to existing APS solutions, it can achieve a high input voltage (≥ 7 kV) with simple circuit structure and control scheme. In this paper, the working principle of the proposed APS is presented and a circuit design example is shown. A circuit prototype with 7 kV input and 15 V/10 W output has been built and tested to verify the effectiveness of the proposed solution.

Abstract: The paper reports on the studies of static and dynamic characteristics of 30 kV diode stacks based on 4H-SiC drift step recovery diodes (DSRDs). It was found that the optimal performance in terms of blocking voltage and switching speed can be achieved with 2 kV DSRD dies. Fifteen 2 kV DSRD dies were connected in series and sealed with molding compound. The stacks were dynamically tested in a special oscillator circuit. Repetitive voltage pulses of 30.5 kV with the leading edge of 1.6 ns were demonstrated.

Abstract: This paper presents the design and development of a 30-kW 3D printed based air-cooled silicon carbide (SiC) inverter for electric vehicle application. Specifically, an all-SiC air-cooled power module is designed, aiming at reduced thermal resistance for high temperature and high power density operation. The module assembly incorporates three major parts: an optimized 3D printed heat sink, a SiC MOSFET phase leg module, and a two-channel gate driver. The electrical and thermal performance of the power module is evaluated through double pulse test and continuous operation. Based on the air-cooled power module, a three-phase half-bridge voltage source inverter with 3D-printed air duct is built and tested to further verify the performance of the power module.

Abstract: Full SiC half-bridge power modules (HPMs) applicable to a real electric vehicle 40-kW permanent magnetic in-wheel motor with an internal diameter of 159 mm have been designed, prototyped and characterized for the first time in the NEDO-SIP program. The prototyped HPMs are extremely compact in size at D35.7×W18.8×H8.0 mm and capable of withstanding junction temperatures up to nearly 200°C. Double-pulse tests revealed that the tested HPM showed steady switching behavior even at 600 V/160 A.

Abstract: A high-temperature silicon carbide power module using CMOS gate drive technology and discrete power devices is presented. The power module was aged at 200V and 300 °C for 3,000 hours in a long-term reliability test. After the initial increase, the variation in the rise time of the module is 27% (49.63ns@1,000h compared to 63.1ns@3,000h), whilst the fall time increases by 54.3% (62.92ns@1,000h compared to 97.1ns@3,000h). The unique assembly enables the integrated circuits of CMOS logic with passive circuit elements capable of operation at temperatures of 300°C and beyond.

Abstract: This paper presents the experimental results of static and dynamic characteristics of the newly developed 14 kV 4H-SiC high-speed drift step recovery diode (DSRD) for pulse power applications for the first time. The feature of the diode structure is to be designed based upon the p+/p-/n+ structure and is to make an additional extremely low doping and thin n-drift layer between the p-drift layer and n+ substrate. This device successfully exhibits higher breakdown voltage of 14kV and high-speed voltage pulse in a range of a few nanoseconds, simultaneously.

Abstract: In the present work, the prototype of a voltage multiplier represented as the diffusion-welded stack is presented. Two options of multiplier prototypes are considered: the scheme with external capacitors and the multiplier of the vertical composition using the diode's own capacitance. Oscillograms of input and output signals for both multiplier composition are presented.

Abstract: This paper discusses Wolfspeed’s advances in silicon carbide (SiC) power module packaging, focusing on recent developments in advanced power module heat transfer techniques, the integration of pinfin mechanical structures, and the implementation of advanced die attach materials. Heat spreader materials and novel cooling methods suitable for SiC power modules are presented, focusing on the thermal heat transfer properties and a discussion of the design and prototype experimental impacts.

Abstract: This work investigates the short-circuit capability of SiC cascode by performing two-dimensional electro-thermal TCAD simulations. The effects of the threshold voltage of the SiC JFET on the cascode short-circuit withstand time are studied. A design trade-off between the JFET specific-on resistance and the cascode short-circuit withstand time is determined. The experimental results are also presented.

Abstract: This paper evaluates potential benefits of high voltage (HV) SiC devices in medium voltage (MV) distribution grids. The MV microgrid, that HV SiC devices can benefit most, is selected as the “killer application” and focused in this paper. The design and simulation are carried out to compare Si-and SiC-based grid interface converters for the quantitative benefit assessment both at converter level and system level. The SiC-based converter has significant benefits in weight and size, and shows enhanced performance and functionality on power quality, system stability and low voltage ride through (LVRT) as well.