BRUSHLESS ELECTRIC MOTOR WITH DAMPER WINDING

• US 3,749,991 A
• Filed: 07/20/1971
• Issued: 07/31/1973
• Est. Priority Date: 07/20/1970
• Status: Expired due to Term

• Current Assignee: Masateru Kuniyoshi
• Original Assignee: Masateru Kuniyoshi
• Inventors: Kuniyoshi, Masateru
• Primary Examiner(s): Simmons, G. R.
• Application Number:
  US05/164,402
• Time in Patent Office: 742 Days
• Field of Search: 318/171,175,138,254,439 310/182,183,195,196,197
• US Class Current: 318/400.02
• CPC Class Codes: H02K 29/06 with position sensing devices H02K29/03 takes precedence

Abstract

In a brushless electric motor, a static commutator including thyristors, and an angular position detector for detecting the relative angular position between an armature winding and a d.c. excited rotor are provided. The thyristors are turned on in sequence with a predetermined commutation lead angle by the signals transmitted from the angular position detector. A compensating winding is also provided in addition to a field winding and is wound on the rotor. A d.c. excitation current proportional to the armature current flows through the compensating winding to compensate the magnetomotive force resulting from the armature reaction.

Claims

1. A brushless electric motor comprising:

an armature having a polyphase armature winding;

a static commutator including a plurality of thyristors for alternately applying armature current to said armature winding;

a d.c. excited rotor having a field winding thereon;

an angular position detector for detecting a relative angular position between said armature winding and said field winding;

control means for turning on said thyristors in sequence and with a predetermined commutation lead angle, said control means employing signals transmitted from said angular position detector, a compensating winding on said rotor for generating a magnetomotive force to compensate the magnetomotive force resulting from armature reaction; and

, means for connecting said compensating winding to a source of voltage not induced by said motor.

2. A brushless electric motor according to claim 1, wherein:

said compensating winding is wound on said rotor for generating a magnetomotive force differing in direction from a quadrative axis by said predetermined lead angle.

3. A brushless electric motor comprising:

an armature having a polyphase armature winding;

a static commutator including a plurality of thyristors for alternately applying armature current to said armature winding;

a d.c. excited rotor having a field winding thereon;

an angular position detector for detecting a relative angular position between said armature winding and said field winding;

control means for turning on said thyristors in sequence and with a predetermined commutation lead angle, said control means employing signals transmitted from said angular position detector; and

, a compensating winding on said rotor for generating a magnetomotive force to compensate the magnetomotive force resulting from armature reaction, wherein said compensating winding is wound on said rotor in two parts and one of said parts is wound to generate a magnetomotive force at right angles with respect to a direct axis and said other part is wound to generate a magnetomotive force at right angles with respect to a quadrative axis, whereby, a d.c. excitation current proportional to said armature current flows through said compensating winding generating a magnetomotive force constituting the sum of said two magnetomotive forces generated by said two parts of said compensating winding and differing in direction from said quadrative axis by said predetermined commutation lead angle.

4. A brushless electric motor according to claim 3, wherein:

said compensating winding is wound such that said magnetomotive force at right angles with respect to said quadrative axis is slightly larger than said magnetomotive force resulting from armature reaction.