Power electronics, so to say, industrial electronics has recently made remarkable progress in its technology thanks to the research and development in hardware technology such as power semiconductors for power circuits and microelectronics devices for control circuits and in control technology such as field-oriented control and modern control theory. This article describes the transition and present state of technology in this field, taking primary views on variable-speed drive equipment, and refers to forecast as well.

Power semiconductors are the key devices of power electronics applications, and their advance has expanded the field of application. Especially, the remarkable progress of self turn off devices controlled by signals to gate or base terminal has urged the spread of their applications. In addition to bipolar transistors and GTO thyristors, power MOSFET and MBT (MOS-gate Bipolar Transistor) have been developed and is coming into wide use.
This paper describes the kinds, features, and application region of Fuji's power devices, with a part of their application technology introduced.

Recently, the main current of AC variable-speed drive equipment is the voltage-type PWM controlled transistor inverter used in combination with three-phase squirrel-cage induction motors. Fuji Electric has completed three standard series, roughly classified, of FRENIC4000, FRENIC5000, and FVR, and each series has standard systems of field-oriented controlled inverters, inverters specialized for textile industry use, and so on. This paper introduces the features, capacity line-up, and forecast of Fuji Electric's typical standard series inverters.

The digital control system for variable-speed drive resulted from the development of microelectronics has rapidly increased system functions. In the meantime, it is required that the improvement of quality, productivity, and reliability should quickly meet the needs becoming more sophisticated.
This paper introduces advanced control technology application, simulation technology for pre-evaluation, and fault monitoring and diagnostics as RAS functions with reference to the digital control system for variable-speed drive.

This paper introduces the following examples of the new applications of general-purpose inverters:
(1) Motor speed control system with a pulse encoder
(2) Simplified torque limiting control system
(3) Synchronized control system for machine axes with a pulse encoder
(4) Main spindle drive system of a press
The system from (1) to (3) are applicable to the inverters of small capacity (22kW or less), FVR-G5. The system (4) is applicable to the inverters of medium and large capacity (30kW or more), FRENIC5000-G5 series.

The planning and manufacturing of high-voltage converters have rapidly been made easy by applying high-voltage power devices and optical pulse transmission systems.
Fuji Electric has accumulated experiences in this field through supplying many products.
This paper gives an outline of converter application to starters for a generator-motor for pumped storage and a blast furnace blower motor and static var compensators (SVC) out of the recent typical products.

Together with the development of GTO thyristors, studies have rapidly been promoted on the electric car drive system with voltage source inverters and induction motors.
Fuji Electric applied 4500 V, 3000 A, reverse-conducting GTO thyristors and investigated PWM converters, inverters, and main transformers. Then, it manufactured a prototype equipment and carried out overall ground bench test to obtain various data. This paper introduces an outline of the above.

As high-voltage and large-capacity GTO thyristors became available, their application to the field of electric railways have increased. As an example of application to traction facilities, a DC circuit breaker and regenerative power absorbing equipment are introduced here. The former is static circuit breaker, and is simpler than a thyristor applied circuit breaker because a commutation circuit is unnecessary. It is safe and easy to be maintained. The latter serves as a simple and economical prevention against regeneration failure. Though the system convers regenerative energy into heat by a resistance, the actual results have proved power consumption very low.

The induction heating system has been used widely because it has the merits of high efficiency, automatic operation, easy temperature control, and improvement of working environment. It requires varied frequency and output according to heating conditions and heat capacity; therefore, the high-frequency inverter which can provide an optional frequency is favorably used. Fuji Electric has standardized HF inverters applying thyristors and power transistors ranging from 0.5kHz to 50kHz to comply with various requirements. This paper introduces their standard specifications, features, operation characteristics, and applications.

Power electronics technology has been applied widely to industrial power supplies. Among these, power supplies for resistance heating, surface treatment, and electron beam radiation are introduced here.
Glass manufacture is cited for resistance heating, where an AC power regulator is employed for controlling melting and cooling processes. For surface treatment, a power supply for coloring is cited. Electron beam radiation equipment, whose application has recently spread over various fields, requires DC power supply ranging from a hundred to thousands kilovolts. This paper describes a high-voltage DC power supply of a high-frequency inverter type using power MOSFET.

The elimination of spillways is an efficient means of cost reduction of medium and small hydraulic power plants and its effect is remarkable in Pelton turbines. However, to realize it, speed control, synchronization, and load control so far performed by needles must be done only by deflectors. The Chubu Electric Power Co., Inc. and Fuji Electric Co., Ltd. carried out the verification test of deflector control characteristics first in the world using a prototype turbine, and confirmed that turbine control only by deflectors and elimination of a spillway were possible. This paper gives an outline of the test.

Since there is a continuing tendency toward advanced age and decrease in number of workers in the agriculture of Japan, rice-centers have been built in various places for improving agricultural management.
This monitoring and control system has realized labor saving and automation suitable for the scale of each rice-center, and enables the shortening of waiting time for receipt of grain, improvement of quality control, planned receipt of grain, and unmanned operation in the night.
This paper introduced the features, configuration, and functions of the system.