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US 4,750,077 AGranted
Coil device
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorNobutada Amagasa
Life of this patent
Estimating the term…
Abstract
The distributed capacitance between coil turns in a coil device is increased, and a coil inductance and a low-pass filter are formed, whereby overvoltages and high frequency voltages are suppressed. The increased distributed capacitance is attained by inserting a ferroelectric insulator, such as a ceramic material, between the coil turns or by winding a metal foil-containing insulator film in the shape of a tape, round a coil conductor.
Claims13
A dynamo electric machine, comprising:
- a field induction coil means including a coil having spaces between the coil turns thereof,
- a power supply circuit including semiconductor elements for supplying electrical power to said coil,
- switching means for disconnectably electrically connecting said coil and said circuit, and
- means in said coil means for absorbing overvoltage generated when current in said circuit is abruptly varied by activation of said switching means, whereby said semiconductor elements in said circuit are protected from the overvoltage, said overvoltage absorbing means being constituted by a low-pass filter formed of the inductance of said coil and ferromagnetic insulator inserted in said spaces between said coil turns so as to increase the distributed capacitance between said coil turns.
1 more element
An electrical power supply circuit, comprising:
- a coil means including a coil having spaces between the coil turns thereof,
- a rectifying circuit including semiconductor elements for converting A.C. power to D.C. power and supplying said D.C. power to said coil;
- and
- means in said coil means for absorbing overvoltage generated in said power supply circuit when current in said supply circuit is abruptly varied, whereby said power supply circuit protected from the overvoltage, said overvoltage absorbing means being consituted by a low-pass filter formed of the inductance of said coil and ferromagnetic insulator inserted in said spaces between said coil turns so as to increase the distributed capacitance between said coil turns.
1 more element
Dependencies are inferred from the claim text.