US 5,668,450 AGranted

Half-wave, brushless, four-phase DC motor with bifilar windings

AssigneeMartin Marietta Corporation

InventorsDavid Allan Glasier, Joseph Frederick Rubin

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Abstract

A half-wave brushless, four-phase DC motor includes sets of four stator windings fed at 90.degree. phase increments by four switches. The 0.degree. and 180.degree. windings are wound about their magnetic stator poles in bifilar conductor pairs, and the 90.degree. and 270.degree. windings are similarly wound. The bifilar windings are connected to generate the same directions of magnetic fields as the prior-art windings. As a result of the bifilar windings, the magnetic fields of the windings tend to be identical, and all the inductances of each winding tend to be transformer-coupled to the other winding of the bifilar pair. During sequential turn-off of the switches in normal operation, the coupled inductance causes a voltage kick which is poled so it can be damped, and the energy returned to the source, by a diode coupled across the other switch of the bifilar pair. Thus, a half-wave brushless DC motor keeps its advantage of low parts count and simplicity, while gaining the advantages of a full-wave motor in efficiency and voltage spike reduction.

Claims6

Dependent claims

A brushless DC motor adapted to be energized from a direct voltage source including first and second terminals, said motor comprising:

a rotor including a permanent magnet for producing a permanent magnetic field having at least one positive and one negative pole;
a first stator winding including a first terminal electrically connected to said first terminal of said voltage source, and also including a second terminal adapted to be electrically coupled to said second terminal of said voltage source during first intervals, said first stator winding being physically located at a reference angular position about said rotor, such that, when current flows from said voltage source through said first stator winding during said first intervals, a magnetic field is generated at said reference angular position, which magnetic field is capable of interacting with said permanent magnetic field;
a second stator winding including a first terminal electrically connected to said first terminal of said voltage source, and also including a second terminal adapted to be electrically coupled to said second terminal of said voltage source during second intervals different from said first intervals, said second stator winding being bifilar wound with said first stator winding, such that, when current flows from said voltage source through said second stator winding during said second intervals, a magnetic field capable of interacting with said permanent magnetic field is generated by said second stator winding;
first controllable switching means coupled to said second terminal of said voltage source and to said second terminal of said first stator winding, for switching between a conductive state and a nonconductive state in response to first and second portions of a first control signal;
second controllable switching means coupled to said second terminal of said voltage source and to said second terminal of said second stator winding, for switching between a conductive state and a nonconductive state in response to first and second portions of a second control signal;
and
control means coupled to said first and second switching means, for applying said first portion of said first control signal to said first switching means at times which alternate with the times at which said first portion of said second control signal are applied to said second switching means.

4 more elements

A brushless DC motor adapted to be connected to first and second terminals of a voltage source, said motor comprising:

a rotor which maintains a permanent magnetic field;
an elongated bifilar wire defining a first end and a second end, said bifilar wire including first and second conductors, said wire being wound as a stator winding about said rotor;
stator winding source connection means, for connecting said first end of said first conductor and said second end of said second conductor to said first terminal of said voltage source;
first controllable switching means coupled to said second end of said first conductor and to said second terminal of said voltage source, for switching between conductive and nonconductive states in response to a first switching control signal;
first unidirectional current conductive means associated with said first controllable switching means, for conducting in response to a voltage applied across said first controllable switching means during intervals in which said first controllable switching means is in said nonconductive state;
second controllable switching means coupled to said first end of said second conductor and to said second terminal of said voltage source, for switching between conductive and nonconductive states in response to a second switching control signal;
second unidirectional current conductive means associated with said second controllable switching means, for conducting in response to a voltage applied across said second controllable switching means during intervals in which said second controllable switching means is in said nonconductive state;
and
control means coupled to said first and second controllable switching means, for generating said first and second control signals in a mutually alternating manner.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/423,255Filed 17 Apr 1995
Granted: 16 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H02K 3/28
Windings characterised by the conductor shape, form or construction, e.g. with bar conductors: layout of windings or of connections between windings
H02K 21/14
With stationary armatures and rotating magnets: with magnets rotating within the armatures
H02P 6/08
Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position;…:…
H02P 6/24
Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position;…:…