Masanori Arata

Noise Lowering for a Large Variable Speed Range Use Permanent Magnet Motor by Frequence Shift and Structural Response Evaluation of Electromagnetic Forces

According to electrical output up rating of a permanent magnet motor and request to operate for a large variable speed range, resonance between structural natural vibration and electromagnetic force inside the motor can take place and make noise. This paper describes the mechanism of a resonance between them and noise lowering procedure by frequency shift when they are applied to the reluctance torque largely employed new motor named Permanent magnet Reluctance Motor (PRM).

Noise lowering for a large variable speed range use permanent magnet motor by frequence shift of electromagnetic forces causing structural resonance

According to electrical output up rating of a permanent magnet motor and request to operate for a large variable speed range, resonance between structural natural vibration and electromagnetic force inside the motor can take place and make noise. This paper describes the mechanism of a resonance between them and noise lowering procedure by frequency shift when they are applied to the reluctance torque largely employed new motor named Permanent magnet Reluctance Motor (PRM).

Comparison of Brush Dynamic Operation Characterisitics for Turbine Generator Steel Collector Ring

In large turbine generators for thermal or nuclear power plants, such as 1000 MVA power plants, brush & collector ring sliding contact operation characteristics, where more than 5000 A field exciting current flows, are one of the most important problem for its reliability. In case of turbine generator collector ring, ring material is usually made of steel, as a view point of mechanical strength for high speed operation, such as 60 m/s, where brush contact characteristics for the steel ring have not been well known or have not been enough disclosed. Besides collector ring profile distortion which may cause brush seating operation difficulties, has to be allowed to some extent, due to mechanical structure of the turbine generator rotor & machining process feature. These mean that the suitable carbon brush grades for this purpose are limited, even though hundreds of carbon brush grades are supplied all over the world by brush manufacturers. In this paper, results of the carbon brush grades comparison test for evaluating dynamic operation characteristics by applying very high sliding speed condition & very high brush current density condition, are presented. As results of the test, it is clarified that in case of lower apparent density brushes and lower flexural strength brushes among the natural graphite grades, better dynamic operation characteristics are given.

EV and HEV motor development in TOSHIBA

Hybrid Vehicles (HEVs) and Electric Vehicles (EVs) improve the efficiency of a drive and reduce CO2 emissions by regenerative braking and operating the engine under optimum conditions. It is desirable to decrease the motor size and increase the maximum torque to minimize the driving units. For these purposes, motors employing permanent magnets have been commonly used recently. For HEVs and EVs motors, Toshiba developed the reluctance torque largely employed new motor named PRM, and has been applying to various vehicles. This paper describes the current motor development status in TOSHIBA.

Technologies for high efficiency large capacity turbine generator

For large capacity turbine generators of thermal power plants, water-cooling system has widely been applied to stator windings. TOSHIBA has developed generators using hydrogen indirectly cooled windings, which are more suitable for high efficiency and easy to maintain, with capacity of 670MVA and efficiency of 99.1%. As the bars of stator windings are cooled with hydrogen gas through the insulation surrounding the bars, it is important to suppress the temperature rise. In this paper, some technologies to realize high efficiency turbine generators, such as multiple parallel circuit winding to reduce current per single bar and ventilation system optimization are described.

Comparison of Brush Contact Drop Characteristics with Copper Ring and Steel Ring, Considering Spark and Collector Ring Hazard

Brush and collector ring system is applied to rotating machines, such as large synchronous generator for thermal and hydraulic power plant and large AC synchronous and wound rotor induction motors for industrial applications. Recently as results of power electronics technology & microcomputer control technology, inverter fed AC adjustable speed large synchronous motor for steel rolling mill and variable speed water turbine generator with AC excitation wound rotor have been developed, realizing excellent performance. In these rotating machines, not only large current capacity but also high performance reliability is required to brush/collector system From these back ground, authors try to introduce new theory to brush/collector system, based upon more than one hundred years of brush/collector ring application histories and based upon some experiments by testing machine, which are introduced by field experiences of those machines.