The important points of development of power semiconductor devices are their steady transition with the timely overlap with higher power, more advanced functions, and more intelligence. The trend toward more advanced functions is mainly described by taking the high h_FE power transistor, inverter MOSFET, MBT (IGBT), various high-speed diodes, GTO thyristors, and other new Fuji Electric products as examples. The advantages and the first generation device concept, and current development approach of the intelligent power devices which are the most important development theme of the future are described.

High h_FE power transistor modules were developed to reduce the base current and standardize the drive circuit to meet the need for high efficiency and compact inverters. By optimizing the npn three-stage Darlington chip pattern and making the cell finger, an h_FE more than 10 times higher than conventional devices was obtained and drive by 0.1A base current up to 150A class was made possible. The development objectives and the chip design, series, and rated characteristics of these new power transistor modules are introduced.

A new type of power MOSFET optimum for inverter applications has been developed. It is a power MOSFET with an on-chip free-wheeling di/dt resistance and L load switching resistance, which are defects of conventional devices, of more than 10 times that of conventional products and which can be used in inverter applications without an external protection diode or other protection circuit. This new power MOSFET was achieved by the development of new process technology and a new cell structure.

In the field of static power inverters, the trend is toward an increase of the switching frequency to 10kHz or higher to reduce their size and weight and to lower the audio frequency band noise. The MBT (IGBT) is an element which can control high power by a high frequency to meet this demand. MBT (IGBT) modules have now been serialized up to almost the same capacity as bipolar power transistors. The series, structure, characteristics, and application technology of these MBT (IGBT) modules are outlined.

Recently, the demand for microwave ovens has expanded noticeably. Of these microwave ovens, the high frequency inverter microwave oven aimmed at improvement of performance and added value have gained special attention. Fuji Electric formerly commercialized a high voltage silicon diode series used in microwave ovens. The ESJC30-05 high voltage silicon diode with excellent high speed operation even at high ambient temperatures, as well as a new high speed switching added to the conventional high current rectification capability and high reliability has been developed and commercialized for inverter microwave ovens in addition to these. This new diode is introduced.

Recently, the development and expansion of various electronic equipment supported by the rapid development of semiconductor technology is being watched. Against this background, Fuji Electric has been developing various fast recovery diodes for and meeting the needs of the switching regulator market which is continuing to demand higher performance, smaller size and lighter weight, and lower price.
In response to the increasingly diverse market needs, a 60V Schottky barrier diode and 300V long loss fast recovery diode have now been developed and serialized. These diodes are introduced.

In the field of spot welders and other DC low voltage, high current power supplies, the development of a high current diode with low loss and fast switching characteristics is desired in order to increase the efficiency and reduce the size and weight of equipment by using high frequencies. A high current Schottky barrier doede (SBD, ERR81-004) with a 3,000A average forward current was developed to meet these needs. The SBD and junction diode are compared and the ERR81-004 is outlined and application examples are given.

A 4.5V 3,000A high power reverse conducting gate turn-off thyristor has been developed.
This device has a pin junction and anode short structure. A 4.5kV blocking voltage, 3,000A turn-off current, and low switching loss were realized.

In Al and Ga diffusion into a Si wafer by ion implantation, the electrical activity of the Al and Ga can be increased by using a multilayer made of silicon oxide and silicon nitride.
This multilayer protects the implanted ions from out-diffusion. In this way, good electrical activities of 80% for Ga and 5% for Al can be obtained. This new implantation technique has been successfully applied to the fabrication of a 115mm diameter, 6kV 2,500A light-triggered thyristor.

The order received by Fuji Electric to renew ten approx. 7.4m runner diameter large Kaplan runners for the Wells Dam in the U.S.A. is introduced as an example of renewal of hydroelectric power stations which has increased recently inside and outside of Japan recently. This plan is intended to increase the annual power product by increasing the turbine efficiency and the maintenance cost by renewing 10 Kaplan runners. This power station was constructed 20 years ago and nine of ten Kaplan runners have been obliged to be operated by fixing runner blades due to various troubles. This order was awarded to Fuji Electric resulted in the recognization of high efficiency of the Fuji Electric Kaplan runner which were certified by the competition of model runner development for one year with a worldwide manufacture.

The Palmiet pumping generators (250MVA×2) are the modern generators with rim ventilation cooling system, oil circulation system by self-pumping action of bearing, and magnetic bearing to improve effici. ency and bearing reliability. Moreover, the static converter starting system was developed, in which the control and monitor of starting devices are executed by an advanced Direct Digital Control System (DDC) Ample results were obtained from site testing of these machines and the unit No.2 was placed into commercial operation in April 1988 and the No.1 units was placed into commercial operation in May 1988. Part of the site test results obtained are introduced.

In the short-circuit test laboratory, which certifies the short-circuit performance of electric power circuit breakers and GIS, transformers, cables, etc., stricter certification conditions, multiplexing and higher precision of measurement data, and more advanced data analysis are demanded to improve the reliability of equipment development.
The automatic measurement and equipment supervision by computer which considers surge countermeasures unique to the electric power field completed by Fuji Electric is outlined. The current state and newest technology of synthetic short-circuit testing are also introduced.

Refuse incineration plants are beautiful buildings which blend with the terrain and are a mass of many facilities. To operate these facilities effectively and safely, an instrumentation and control system which includes a computer is necessary.
The panel operation type IICS-100 and panel less operation type IICS-1000, which are two typical types of incinerator instrumentation and control systems (IICS), are outlined and their system configuration and incineration software package are introduced.