Simplified hybrid-secondary uncluttered machine and method

Abstract

An electric machine (40, 40′) has a stator (43) and a rotor (46) and a primary air gap (48) has secondary coils (47c, 47d) separated from the rotor (46) by a secondary air gap (49) so as to induce a slip current in the secondary coils (47c, 47d). The rotor (46, 76) has magnetic brushes (A, B, C, D) or wires (80) which couple flux in through the rotor (46) to the secondary coils (47c, 47d) without inducing a current in the rotor (46) and without coupling a stator rotational energy component to the secondary coils (47c, 47d). The machine can be operated as a motor or a generator in multi-phase or single-phase embodiments. A method of providing a slip energy controller is also disclosed.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH [0001] This invention was made with Government support under Contract No. DE-AC05-00OR22725 awarded to UT-Battelle, LLC, by the U.S. Department of Energy. The Government has certain rights in this invention.TECHNICAL FIELD [0002] The field of the invention is brushless machines, including both ac and dc machines, including both motors and generators, and including induction machines, permanent magnet (PM) machines and switched reluctance machines. DESCRIPTION OF THE BACKGROUND ART [0003] A brushless doubly-fed induction motor (BDFIM) has two sets of stator windings for two p-poles and two q-poles. The rotor winding has a nested cage with 2(p+q) poles. It produces a motor control with a relatively narrow range of speed control. The existing extended rotor cage technology has a drawback in that the both rotational and slip energy are transferred in a cluttered approach to energy transfer. [0004] An induction machine may be viewed as a t...

AI Technical Summary

Benefits of technology

[0011] This invention provides a simplified form of the hybrid-secondary uncluttered machine in which there is only a stator and a slip energy rotor. The invention eliminates the main rotor and the auxiliary rotor with windings which were present and electrically connected in the prior art. The stator and slip energy rotor are now magnetically coupled and a slip energy source is provided by peripheral transformer coils in which slip current is induced through the magnetic coupling through a rotor without windings.

[0014] This invention further simplifies and improves the earlier machine. It eliminates two large rotating cores and their windings from the earlier machine. It provides higher efficiency due to less copper loss resulting from the elimination of the rotor windings. It can operate at any speed that including synchronous speed. It is smaller in size per unit of power than prior uncluttered machines and can be manufactured at lower cost.

Problems solved by technology

The existing extended rotor cage technology has a drawback in that the both rotational and slip energy are transferred in a cluttered approach to energy transfer.

However, maintenance of a motor with slip rings and brushes is expensive.

The high cost of adjustable speed drives fed by an adjustable-frequency inverter discourages many potential users.

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