Toward establishing low carbon societies, expectations are rising significantly for diffusion of renewable energy such as photovoltaic power generation and wind power generation as well as power electronics technology, which uses such energy efficiently,. In order to meet these expectations, Fuji Electric is developing user-friendly power semiconductor products with high energy conversion efficiency and low noise for various sectors such as environment, energy, automobile, industrial machinery, social infrastructure and home appliances.
This special edition introduces the latest technology and products of power semiconductors, which are the key devices of power electronics technology.

Fuji Electric is developing environmentally friendly power semiconductor products with high energy conversion efficiency and low noise. These products are applied to various sectors such as environment, energy, automobile, industrial machinery, social infrastructure, and home appliances, and they contribute to the world. This paper describes the current status and future outlook of power module products, including an SiC hybrid module, ultra-small all-SiC module with high reliability, high-power IGBT module for a 3-level power converter and IPM for a hybrid electric vehicle; power discrete and power IC products, including the second-generation LLC current resonant IC and IPS for one-chip linear control; and element technology that supports these products.

In place of Si devices, silicon carbide devices (SiC devices) featuring heat resistance and high breakdown fi eld tolerance are raising expectations for effi ciency improvement and miniaturization of equipment. Fuji Electric is moving ahead with the development of a 1,700 V withstand voltage SiC hybrid module for high-effi ciency inverters (690 V series). A SiC-SBD chip jointly developed with the National Institute of Advanced Industrial Science and Technology has been applied to a freewheeling diode (FWD), and a Fuji Electric’s“ V-Series” IGBT chip has been applied to an insulated gate bipolar transistor (IGBT). By improving leakage current and switching characteristics, the module has been verifi ed to be capable of reducing generated loss by approximately 26% in a 300A product compared to the conventional Si modules.

SiC devices have excellent characteristics that realize high blocking voltage, low power dissipation, high-frequency operation and hightemperature operation. Fuji Electric’s all-SiC modules feature direct bonding layout for semiconductors and a plastic molding structure. Compared with the conventional product, All-SiC modules have achieved a reduction of 50% in footprint, 75% in inductance and approximately 35% in switching loss. Moreover, for using high power drives, switching was demonstrated to be available even if four modules are connected in parallel. All-SiC modules were verifi ed to have higher reliability in high temperature and humidity, in addition to power cycling, than the conventional products.

In order to meet the needs for miniaturization and cost reduction of inverters, IGBT modules are required to off er higher power density than ever. Fuji Electric has developed a new aluminum wire, solder alloy and surface electrode protection layer to improve the continuous operating temperature of an IGBT module from the conventional 150°C to 175°C, thereby realizing higher power density. A power cycle lifetime has been more than doubled compared with the conventional products in all temperature ranges, and thus 20% improvement of inverter maximum output can be expected.

Recently, renewable energy has been attracting attention and, photovoltaic and wind power generation markets are growing rapidly in particular. In these fi elds, low- and medium-power IGBT modules are often connected in parallel to realize high power converters; but this will cause high surge voltage due to wiring inductance. Fuji Electric is developing one package for high-power IGBT modules for 3-level power converters. Improvement for power conversion effi ciency and miniaturization of equipment can be expected. It has also realized a laminated structure for the main terminal bus bar to reduced internal inductance.

Intelligent power modules (IPMs) control the power of hybrid vehicles. IPMs are needed to be downsized and lightweight due to the request for fuel effi ciency and comfort. To achieve these requirements, Fuji Electric has developed a high-capacity IPM for hybrid vehicle integrated buck-boost converter and two inverters. This time, we have developed cooling design technology and high-strength solder technology, which realize a direct liquid cooling module with an integrated aluminum heat sink. This product has achieved a product volume reduction of 30% and mass reduction of 60% compared with the conventional indirect cooling structures and high reliability required for vehicles. The mass production of the product has already begun.

When an IGBT module is mounted, thermal grease is applied between the cooling fi n and the IGBT module to promptly transfer the heat generated from the IGBT module. An increasing number of customers are requiring IGBT suppliers to perform this thermal grease application. To meet this requirement, Fuji Electric has developed a family of IGBT modules with pre-applied thermal interface material (TIM) of phase change type. The adopted TIM features a high heat dissipation performance that is three times or better than that of the conventional products, and is liquefi ed at around 45°C and solidifi ed below that temperature, thus off ering ease of transportation. This has realized IGBT modules with improved heat dissipation properties and reliability (thermal management).

LLC current resonant power supply, which is characterized by soft switching, resonance control with a duty ratio of 50% and leakage transformer structure, is suitable for effi ciency improvement, noise reduction and profi le lowering in switching power supply. Fuji Electric has developed the 2nd generation “FA6A00N Series,” which inherits the characteristics of the 1st generation LLC current resonant control IC,“ FA5760N,” and is enhanced with lower standby power and improved protective functions. It integrates the world’s fi rst high-precision secondary side over-load protection function while further reducing the standby power by approximately 20%. For the over-current protection function, the delay time can be externally adjusted.

In the fi eld of vehicle electrical components, the increasing demands for miniaturization, reliability improvement and functional enhancement are required. To meet these demands, Fuji Electric has developed one-chip linear control intelligent power switch (IPS),“ F5106H,” which mounts a high-precision current detection amplifi er on the conventional IPS. Applied with 4th generation IPS device and process technology, it can be integrated into one chip and mounted in a SOP-8 package. In addition, the maximum rating of the junction temperature has been set to 175°C to improve the durability in a harsh temperature environment, and low power operation voltage can be allowed down to 4.5 V.