It is over 20 years since power electronics came on stage as a new technological field fusing electronics, control, and electric power. Its application has spread over industrial systems, and then, over various systems for transportation, electric power, consumer goods, and information. It is now one of the fundamental technologies supporting modern industries.
This paper describes an outline of developments in the latest Fuji power electronics laying stress on power supplies.

Power electronics products have rapidly come into use in the industrial field with the progress of power devices and the development of circuit and control technology. The trend of power device development is now toward the improvement of IGBTs that can perform high-speed switching and have a wide range of capacities. This paper introduces IGBT technology that is expected to be the core of future power devices, (1) gate drive circuits, (2) snubber circuits, (3) IGBT stacks.

Fuji Electric has developed large-capacity UPSs using IGBTs, UPS600-A/3 series, which used a PWM converter for a large-capacity UPS first in the world and realized low power input and high power factor.
As for the PWM inverter, a new control system realized instantaneous value control in parallel UPS operation and greatly improved output performance.
With regard to IGBT circuit that support these technologies, IGBT power modules were fabricated using technologies such as large-current printed-circuit boards and heat-pipe cooling.

With the progress of computer downsizing and network system distribution, demand for small and medium-capacity UPSs has increased and their duty has become important.
Fuji Electric has put on the market new UPSs using IGBTs, UPS600-C/1 and C/3, which have high reliability, high performance, small size, and good maneuverability and maintainability, and can meet the latest various needs.
This paper describes the features, standard specifications, circuitry configurations, and test results of UPS600-C/1 and C/3.

Former 400-Hz uninterruptible power systems (UPSs) wear short of no-break power transfer (NBPT) ability required by the latest aircraft. Fuji Electric has developed a new 400-Hz UPS with IGBTs. Its distinctive features are full functions for NBPT, high efficiency, high reliability, easy maintenance, guidance with LCD, cable drop compensation, instantaneous power failure protection, and 12-phase rectifier to reduce high harmonic currents. This paper introduces the specifications, features, and test results.

As power electronics appliances rapidly came into wide use, instantaneous voltage drop in power systems caused by lightning and troubles due to subsequent harmonic currents have been actualized. Further, many problems such as peak power demand in summer and environmental protection for conventional emergency generation sets using fossil fuel have come up. Fuji Electric has developed a power-storing emergency power supply system, which is a multipurpose unit solving all these problems with a converter. This paper introduces the specification, brief descriptions, circuitry configuration and test results.

On-site (consumer-owned) fue cell power units of comparatively small capacity, 50 to 500 kW, require high generating efficiency, small size, light weight, and low noise. Fuji Electric has developed 50 and 100 kW inverters used for these units using high-frequency switching devices: MOSFETs and IGBTs. The use of high frequency technology makes inverters small, light, lownoise and high-efficiency. This paper introduces the specifications, features, circuitry configurations, control systems, and test results.

Since the oil crisis in 1973, photovoltaic power generation has attracted attention as one of alternative energy resources and now it has being promoted toward practical use under global interests in environmental problems. In these circumstances, Fuji Electric has developed a high-performance inverter for photovoltaic power generation systems for practical use adopting IGBT modules.
This paper introduces its features, specifications, circuitry configuration, and characteristics.

The diffusion of various power electronics appliances has caused problems of higher harmonic currents into power systems and reactive power.
To solve these problems, various systems for improvement by PWM control technology using self-quenching elements are invented and put to practical use.
This paper gives an outline of current source PWM converters with large capacity over hundreds kW which have realized great reduction in higher harmonic currents and a high power factor of 1.0.

The high-frequency (HF) inverter which is an important part of induction heating systems requires varied frequency and output according to heating conditions and heat capacity. Fuji Electric standardized HF inverters of 0.5-5.0 kHz and 20-4,000kW with thyristors and power transistors. Recently, it has developed a new series of higher frequency inverters of 20-100 kHz and 10-500 kW applying power MOSFETs. This paper introduces their standard specifications, features, circuitry configurations, structure, and applications.

Active filters are coming into wide use in place of conventional L-C (passive) filters. Fuji Electric has standardized the products of 50 to 400 kVA for industrial use, which is introduced in this paper.
The active filter is a multifunctional filter having power factor compensation, voltage variation compensation in addition to harmonic current compensation, and it is expected that its applications will spread in future.

Reduction in size and weight is demanded by industrial power supplies below hundreds kW installed near load to reduce floor space, construction expenses, and power loss. Improvement in functions and performance aiming at high productivity and labor reduction of labor is also demanded.
Fuji Electric has completed a high-frequency inverter type DC supply with IGBTs applying former basic technology of high frequency and new technology of high frequency and large current. This is a high-performance unit much smaller and lighter than former types. It has been operated satisfactorily after installed.

Uninterruptible power systems and industrial DC power supplies require improvements in size and weight and in electrical performance. To satisfy these requirements, Fuji Electric has developed a new-type AC-DC converter, which uses a bilateral IGBT switching module, converts directly utility power frequency into 16 kHz, insulates output from input using a high-frequency transformer, and rectifies a high frequency alternating current.
This paper introduces the development of a prototype with DC output of 30 kW.