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General-Purpose Inverter Technologies Inverter User’S Success Stories Nowadays, Fuji Electric Inverters Are Indispensable to Your Systems

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General-Purpose Inverter Technologies Inverter User’S Success Stories Nowadays, Fuji Electric Inverters Are Indispensable to Your Systems Whole Number 182 General-Purpose Inverter Technologies Inverter user’s success stories Nowadays, Fuji Electric Inverters are indispensable to your systems. Research laboratory equipment We are assured of precise control Commercial-use washing machines with these inverters. Even with the large volumes of wash, our machines can start up Automated parking garage powerfully. Our powerful inverters enable vehicles to be lifted very smoothly. Rotary press for printing machine The inverter assures stable, high-speed operation of the machine. Warehouse conveyor system Our heavy cargo is conveyed Mini-conveyor system smoothly. The key is using inverters. It doesn’t matter how much fish I load on the conveyor, it always carries them smoothly. Sushi-serving rotary conveyor system Our compact and easy-to-operate inverters are also at work here. FVR-E9S FRENIC5000P9S FVR-C9S FRENIC5000G9S series series series series Fuji Electric can provide you with the products best suited to meet your requirements. The torque-vector-control type FRENIC5000G9S series is For mini-conveyors and ventilation fans, use the FVR-C9S ideal for use in washing machines for commercial use and series which offers you simplified operation and low cost. automated parking garages. Fuji Electric can supply you with inverters conforming with the The FRENIC5000P9S series is best suited for variable-speed EN Standards, UL Standards and/or the cUL Standards. applications such as fans, and pumps. The FVR-E9S series featuring high environmental protection performance is suitable for wood-working machines etc. Fuji Electric Inverters General-Purpose Inverter Technologies CONTENTS Present Status and Future Prospects 70 for General-Purpose Inverter Technologies Novel Technologies for Power Conversion Circuits 74 Noise Reduction Methods for Power Electronic Equipment 78 Recent Variable-Speed Drive Technology 82 Cover Photo: Variable-speed drive systems Downsizing Technology for General-Purpose Inverters 85 such as general-purpose inverters are used in mechanical equipment in various industrial fields and con- tribute to automation, reduction in labor, and advance in performance for the equipment. Since having marketed general- Large-Capacity Variable-Speed AC Drive 90 purpose inverters first in the indus- try in 1977, Fuji Electric has taken the lead in promoting their total digitization, downsizing, advances in performance and functions. The cover photo, which pictures a motor for machine tool spindle FRENIC5000MS5 for Machine Tool Spindle Drives 95 drive and general-purpose inverters conforming to the international standard, is aimed at imaging quick acceleration/deceleration and smooth speed control performances. Head Office : No.12-1, 1-chome, Yurakucho, Chiyoda-ku, Tokyo, Japan Present Status and Future Prospects for General-Purpose Inverter Technologies Takao Yanase Shinobu Kawabata 1. Introduction requires an AC reactor on the power supply side. In addition, according to the condition of the power Variable-speed drive systems, typically represent- source, an LC filter must be added. Therefore, this ed by general-purpose inverters and servo systems, are method requires further amplification and cost reduc- used in many industrial fields. They contribute to the tion. energy savings, automation, labor savings, and high- To meet these requirements, Fuji Electric studied efficiency operation of machines and equipment. Both a direct AC-AC converter system as a new main circuit inverters and servo systems have improved economi- system. We proposed a system to greatly reduce input cally since the advent of power transistors. They have harmonic current without an additional reactor by made rapid progress with the spread of energy-saving regarding the motor winding and converter circuit as a measures due to the oil crisis. unified system. This currently being studied for future This paper outlines the basic technologies that production. (For further details, please see “Novel have driven these developments, modern technologies Technologies for Power Conversion Circuits” in this for future development, and Fuji Electric’s perspective. special issue.) Our abundant product line is also introduced. Fig.1 Typical main circuit of general-purpose inverter 2. Modern Technologies of General-Purpose Inverter Diode Dynamic PWM rectifier DC braking inverter circuit reactor circuit circuit 2.1 Power conversion circuit technologies Variable-speed drive systems typically represented by general-purpose standard inverters have realized AC reactor Motor small size and high efficiency through the use of low- Power loss power devices such as insulated-gate bipolar supply M transistors (IGBTs), a high-efficiency cooling technolo- gy, and a large-scale integration technology using Smoothing capacitor metal-based printed circuit boards. These develop- ments will be pursued and should prove successful in the future. From the viewpoint of main circuit systems, most drive systems are composed of a diode rectifier circuit Fig.2 Inverter circuit with PWM converter and a PWM inverter circuit, as shown in Fig. 1. This combination has been used since its inception and PWM seems to be well established technically and economi- converter Inverter circuit circuit cally. However, it requires a dynamic braking circuit to dissipate the regenerated energy during braking AC reactor and harmonic current generated in the input power Motor source. One general method of reducing harmonic Power current is to connect a DC or AC reactor, as shown in supply M Fig. 1. To efficiently return regenerated energy to the power source during braking and to greatly reduce Smoothing capacitor input harmonic current, the PWM converters shown in Fig. 2 have come into use. However, this method 70 Vol. 44 No. 3 FUJI ELECTRIC REVIEW and commercial districts. The present method of 2.2 Noise reduction methods satisfying these limits in inverters and servo systems Electronic equipment such as inverters and servo is to connect a filter in the power supply circuit and systems performs high-efficiency power conversion by uses shielded wires on the main circuit to the motor. high-speed switching with IGBTs. But this high-speed Fuji Electric is actively researching the noise switching causes high frequency noise. generation mechanism and transmission process, In other countries and regions around the world, IGBT soft switching methods to suppress noise, and this noise has come under regulation based on the noise reduction methods for DC-DC converters for the recommendation of the IEC (International Electrotech- control power supply. (Please refer to “Noise Reduc- nical Commission). tion Methods for Power Electronics Equipment” in this Figure 3 shows an example of noise terminal special issue.) voltage measured in an inverter and the limit values. The curve with a note of CISPR class B ③ shown 2.3 Control technologies between the data without the noise filter ① and with Due to progress in microprocessor and gate array the noise filter ② is the limit value (recommended LSI technologies and technical development in motor value) for connections to power sources in residential control techniques, the control technologies of inverters and servo systems have been advancing every year. Fig.3 Example of noise terminal voltage (measured and limit In addition to technologies that improve motor values) torque controllability such as sensorless vector control and torque vector control, technical developments that improve application performance such as the tuning of 100 motor control parameters and adaptability control including matching the mechanical system are in ① progress. In the future technologies for further V) µ 80 improving handling ease and for high-efficiency vector control using a general-purpose standard inverter and a general-purpose motor will be developed. To obtain a smooth rotation at a low speed with V/f 60 (voltage/frequency) controlled inverters, many control ③ systems that reduce output voltage distortion and offset have been devised. For example, Fuji Electric 40 developed a special LSI-based digital AVR technology Noise terminal voltage (dB ② which realized smooth rotation characteristics. In addition, a variable-speed drive with general- 20 purpose inverters has up to now been mainly intended 0.1 110100 for induction motors. But to improve operation Frequency (MHz) efficiency, the latest trend is toward driving perma- nent magnet type synchronous motors (PM motors). ① Measured values (without filter) ② Measured values (with filter) However, as demonstrated by conventional servo sys- ③ Limit values (CISPR class B) tems, magnetic pole position or speed sensors are generally used for the PM motor drive. As introduced in the article “Recent Variable-Speed Drive Technolo- Fig.4 A 12-pulse connection for a large-capacity inverter gy” in this issue, Fuji Electric is researching PM motor drive systems that do not require magnetic pole position or speed sensors. 2.4 Harmonic current reduction methods for large- Transformer capacity inverters Harmonic current reduction methods for convert- ers are as described in 2.1, above. However, a transformer is supplied for use by the large capacity converter. The 12-pulse connection system shown in Inverter Fig. 4 is the most economical harmonic current reduc- tion method. Fuji Electric produces a large-capacity inverter M Motor 3 series that can meet 12-pulse connection by the six input terminals of its input rectifier that is divided into two parts. (For details, see “Large-Capacity Variable- Present
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