General-purpose inverters and servo systems have got advantages in both performance and economy through many technical developments and rapidly come into wide use. On the other hand, the spread has posed many problems to be solved such as reduction in noise and harmonics and ease in handling. This paper describes Fuji Electric's current products and technical developments and proposes key words, "user-friendly", "environment-friendly" and "high reliability" as guiding principles for the future development of technologies and products.

This paper describes a new analysis method for three-phase direct AC-AC converters and some of new power conversion circuits as novel power conversion technologies. When applied to various three-phase direct AC-AC converters, this new analysis method clarifies the specific function of each circuit and enables the study of optimal pulse control systems for them. The direct linked type frequency changer is a practical circuit of a direct AC-AC converter without bilateral switches and AC snubber circuits. The new single-phase input high power factor converter is a circuit based on a new principle by controlling the zero-phase-sequence voltage of a voltage source inverter.

Power electronics equipment for improving productivity and saving energy are used widely from factories to homes and expected to further diffuse in the future. However, there is fear that noise emitted by the equipment has an influence upon other equipment. This paper presents methods of noise reduction classified by the source of emission. Noises taken up here are (1) harmonic current emissions, (2) main terminal disturbance voltage, and (3) electromagnetic disturbance emission.

This paper describes the following examples of recent developments in control technology: (1) The digital control of inverter output voltage can generate sine wave current at a very low speed and attains low rotational fluctuation. (2) The application of sensorless vector control realizes automatic acceleration or deceleration in the shortest time, with the drive system controlled at its maximum torque. (3) With regard to the sensorless drive of permanent-magnet synchronous motors which have the advantage of small size and high efficiency, this paper describes the latest researches on starting methods from a stationary or rotating state and control methods at a very low speed.

General-purpose inverters have been reduced in size and price and improved in performance and functions since they came on the market, making spectacular technical progress. The downsizing among these improvements, in which the volume has been reduced to less than one tenth of the first marketing, has greatly contributed to the increase in uses of general-purpose inverters. This paper describes the typical elemental technologies that have been effective in promoting the downsizing.

As inverters for motor drive come into wide use, demands for inverters for large motors become intense. Under the circumstances, Fuji Electric has increased the capacity of inverters and also in consideration of their importance in the installations, front-accessible maintenance and IGBT sections built in the tray have been adopted to facilitate maintenance. This paper describes the features and circuitry configuration of large capacity inverters and also refers to a 12-pulse rectifier and PWM converter as a measure against harmonics currently taking notice.

The FRENIC5000V3/M3 series for machine tool spindle drive was favorably noticed by the market. Recently, however, market requirements have changed, i.e. machine tools have been required to be small-sized, to improve in performance and functions to meet combined machining, and to satisfy various regulations typically represented by the EC directions. To meet these market needs, Fuji Electric has developed the FRENIC5000MS5 series succeeding to the former V3/M3 series. This paper outlines the features and specifications of this new series.

Servo systems that support automation and labor reduction in various industries have used digital control since the 1990s and their uses have increased. To flexibly meet various systems, servo systems are strongly desired to improve in functions and performance and have small-size amplifiers. To meet these requirements, Fuji Electric has developed a new servo system FALDIC-II. This system has its series meeting uses, is applicable to various motors, has ample interfaces for the high-level controllers, and is equipped with a small-size, space-saving amplifier.

In high-precision positioning servomotors, combinations of a programmable controller (PLC) and an exclusive-use positioning device are often used. However, in general industrial machines, there is a growing demand for the positioning function incorporated in the PLC because of lower cost and easier operation. This paper outlines the electronic cam module developed under the circumstances. This module is combined with a servo system and realizes the same motion as a mechanical cam system.

Inverters and AC servo systems have developed into small-size, high-precision, quick-response, multifunctional variable-speed drive equipment. They have been combined with programmable controllers into systems used for various industrial machines with successful results. This paper describes applications of the vector-controlled inverter FRENIC5000VG5 and the AC servo system FALDIC to mechanical equipment for tyre manufacture, packaging, fiber production, conveyance, and semiconductor manufacture.

The EC directions have been fully enforced since 1997, and Fuji Electric has marketed inverters, servo amplifiers, and motors with CE marking. The inverters and servo amplifiers conform to VDE 0160 and IEC664-1 to meet the directions for low voltage, and the specifications have been modified to be more effective against electric shocks. In addition, EN50081-1 and 2 are applied to meet the EMC directions, and in particular, importance has been attached to measures against emission such as shielding for control panels and cables. The specifications of motors are determined to conform to IEC34-1, taking the directions for machines into consideration.

This paper describes the "guideline to reduce harmonic emission caused by electrical and electronic equipment for household and general use" and "guideline to the control of harmonics by consumers of high or special high voltage power supply" which are applied to variable-speed drive systems such as general-purpose inverters and servo amplifiers, and also explains methods of suppressing harmonics and their effects.