Developments of SiC devices and SiC inverters aimed at electric power applications

Abstract

The developments of SiC power devices has been proceeded remarkably since 1990. SiC power devices have been payed attentions as one of the candidate power devices for next HVDC transmissions and its R&Ds have been started in the KANSAI electric power company since 1995. In this paper, a series of R&Ds for the SiC devices and SiC inverters performed in the company are presented from the historical viewpoints.

Development of SiC merged reverse conductive devices

“…A part of this development (FET in Figure 2, TEDREC method in Figure 5) was conducted within R&D framework at Kansai Electric Power Corporation concerning power SiC devices and SiC inverters 2 in which the author was directly engaged. The author is willing to express gratitude to the Kansai Electric SiC team members listed in the list of reference.…”

“…SiC‐based power converters utilizing these functions specific to SiC merged reverse conductive devices can be applied in various fields including electric power equipment, industrial equipment, automobiles and electrified railways, home and office appliances, etc. For example, in case of a load leveler intended for switching between distribution systems in case of fault and provided with voltage sag compensation described in a previous report, 2 the use of 300‐kW power stabilizer would make possible a load leveler (Patent 3759512) with emergency power source function before start‐up of large‐scale private power generation equipment. Below, structure, performance, and features of SiC merged reverse conductive devices shown in Figure 1 are explained by example of 4H‐SiC.…”

“…Thus on‐voltage degradation in 4H‐SiC bipolar devices aggravates with the passage of time. As a result, when stacking faults are locally unevenly distributed, local resistance grows extremely, and performance declines; moreover, local damage occurs 2,6 . When such elements impaired by on‐voltage degradation are included in a module combining multiple elements, current imbalance occurs between the elements, thus causing decline in performance or damage of the module.…”

“…Bipolar devices like SiC pn ‐diodes, SiC‐IGBT, and SiC commutation‐type GTO (SICGT) 2 also demonstrated great advantage over Si devices; SiC inverters and other devices have been developed for electric power equipments aiming at next‐generation electric distribution grid 4 and power load leveling systems 2 . Bipolar devices are advantageous in low loss due to conductivity modulation and in weak temperature dependence of on‐voltage (forward voltage); however, development was focused high‐voltage power applications where negative influence of SiC's high built‐in voltage become relatively smaller than that in medium‐and‐low berakdown voltage region.…”

“…As compared to Si devices, SiC devices promise much better characteristics, including low loss, high breakdown voltage, high thermal resistance, and high power capacity; development of these devices for power electronics has been advanced worldwide since around 1995 1,2 . Advantages of SiC unipolar devices over Si devices in terms of performance and application merits have been rapidly demonstrated, and partly utilized in automobiles, home appliances, electrified railways, and other industries.…”