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New developments in the design of high-speed electric trains are discussed, with particular reference to the induction motor drive system. A new high power three level converter-inverter system applying advanced insulated gate bipolar transistors (IGBTs) is described. Advanced control techniques lead to a unity power factor seen by the ac supply as well as minimising the line harmonics, power loss, motor torque ripple, and audible noise. By using advanced ac inverter drive systems the recently developed high speed train offers high level performance, efficiency, and passenger comfort.The described system is implemented in the latest "Bullet" or Shinkansen train sets operating in eastem Japan between Tokyo and Nagano, IntroducfionThe ac inverter drive system can be thought of as consisting of two major parts: the driving part that contains the ac to dc converter, dc to ac inverter, and the induction motors, as well as the control part that consists of the controller circuit and software. This ac drive system has become the most advantageous system for the powering and driving of electric trains. This is because it offers many beneficial features such as high performance, compacmess and lighter weight, easier maintenance due to contact-less circuits and brushless motors, lower cost, and high reliability. In this paper the an advanced high power ac converter-inverter drive system that has been developed at Mitsubishi Electric for the driving of trains will be discussed. Advanced techniques have been applied to the design and development of the four-quadrant ac to dc converter and dc to ac inverter systems of the induction motor drive. This includes the implementation of unity power factor control, multiinterlaced phase shift control, and three level synchronous PWM switching. Additionally, a low harmonic three level P W M control is applied to the inverter.These techniques produce lower harmonics in the traction motor supply, which leads to lower energy loss, torque ripple, and audible noise. In addition, the ac supply sees a unity power factor load, and the supply line harmonics are lowered. This ensures a good compatibility between the converter and the ac supply, as well as leading to reduce power losses, vibration, and noise in the main ac supply transformer. Hence, these control techniques lead to high train perfonnance in terms of efficiency and harmonic control, as well a marked increase in passenger comfort due to lower vibration and noise. In the following sections, details of the recent converter and inverter drive development will be given, Firstly the induction motor drive hardware system will be detailed. Then the next part of the paper will detail the converter topology and various Shoichi Kawamoto, Takeo Matsumoto, and Hideo Obi Mitsubishi Electric Amagasaki, Japan control aspects such as three level PWM switching, unity power factor control, and phase shift control. Finally the inverter system with three level topology and harmonic ripple control will be detailed. Experimental results will be shown t...

The installation and of a 5 MVA, 4.16 kV Distributionlevel Static Reactive Compensator @-STATCOM) was completed in July, 1999 at the Seattle lron & Metals Corporation's new steel recycling facility in Seattle, Washington. The D-STATCOM technology was selected as the preferred option for voltage flicker compensation of a 4,000 Hp shredder motor, which will be operated at the new facility. For voltage flicker applications, the D-STATCOM technoiogy provides rapid-response compensation to c o w 3 for the voltage fluctuation characteristics imposed on the interconnected system during the shredder motor operation. In this application, the D-STATCOM System will be operating at 4.16 kV and will provide reliable power quality for both the new steel recycling facility and the interconnecting utility, Seattle City Light, which provides power to the plant at 26.4 kV. Final field testing and commissioning of the D-STATCOM System was completed in February, 2OOO.

Measurement of fluctuation in plasma is important for studying the improvement in plasma confinement by the formation of the plasma confinement potential. The density fluctuation is observed by microwaves by methods such as interferometry, reflectometry and Fraunhofer diffraction method. We have constructed a new multichannel microwave interferometer to measure the plasma density and fluctuation radial profiles in a single plasma shot. We successfully measured the time-dependent density and line-integrated density fluctuation radial profiles in a single plasma shot using the multichannel microwave interferometer. Thus, we have developed a useful tool for studying the improvement in plasma confinement by the formation of plasma confinement potential.