COMPATIBLE PERMANENT MAGNET OR RELUCTANCE BRUSHLESS MOTORS AND CONTROLLED SWITCH CIRCUITS

• US 3,678,352 A
• Filed: 11/06/1970
• Issued: 07/18/1972
• Est. Priority Date: 11/06/1970
• Status: Expired due to Term

• Current Assignee: Burnice D. Bedford
• Original Assignee: Burnice D. Bedford
• Inventors: Bedford, Burnice D.
• Primary Examiner(s): Rubinson, Gene Z.
• Application Number:
  US05/087,484
• Time in Patent Office: 620 Days
• Field of Search: 318/138,254,696,685
• US Class Current: 318/400.41
• CPC Class Codes: H02K 29/06 with position sensing devices H02K29/03 takes precedence
• CPC Class Codes: H02P 25/0925 wherein the converter comprises only one switch per phase

Abstract

Brushless motors have physical and electrical characteristics to be compatible with energization by the simple square or stepped wave voltages easily produced with inverter type motor control circuits having a small number of controlled switches responsive to a rotor position sensor. These motors employ a few pairs of opposing non-distributed stator windings arranged overlapping or non-overlapping with a predetermined winding pitch, and a constant gap magnetically polarized or non-polarized rotor with pole faces having related angular dimensions, to thereby produce rectilinear back emf voltages with approximately the same wave shape as the energizing voltages. The circuits can control the applied voltage to adjust motor speed.

Claims

1. A compatible brushless motor and motor control circuit comprising an annular stator member supporting a plurality of opposing pairs of concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relatIon to a rotatable ferromagnetic rotor, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, a motor control circuit comprising only a few controlled switches for applying simple substantially rectilinear wave shape energizing voltages of both polarities to said pairs of stator windings, the winding pitch and location relative to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing voltage applied by said motor control circuit, and control means responsive to the instantaneous position of said rotor for rendering conductive said controlled switches for desired intervals of conduction to energize said pairs of stator windings in a sequence to produce continuous torque to rotate said rotor in a given direction, wherein there are only three opposing pairs of series connected concentrated stator windings, said motor control circuit comprises a pair of alternately conducting controlled switches for each pair of stator windings, said controlled switches being solid state controlled devices, said three opposing pairs of concentrated stator windings each having a winding pitch of about 90* and each stator winding overlaps the adjacent stator windings by about 30*, and said rotor pole faces have a circumferential length of about 90*, whereby the brushless motor is suitable for square voltage wave shape energization.

2. A compatible brushless motor and motor control circuit comprising an annular stator member supporting a plurality of opposing pairs of concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relation to a rotatable ferromagnetic rotor, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, a motor control circuit comprising only a few controlled switches for applying simple substantially rectilinear wave shape energizing voltages of both polarities to said pairs of stator windings, the winding pitch and location relative to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing voltage applied by said motor control circuit, and control means responsive to the instantaneous position of said rotor for rendering conductive said controlled switches for desired intervals of conduction to energize said pairs of stator windings in a sequence to produce continuous torque to rotate said rotor in a given direction, wherein there are only three opposing pairs of series connected concentrated stator windings, said motor control circuit comprises a pair of alternately conducting controlled switches for each pair of stator windings, said controlled switches being solid state controlled devices, said three opposing pairs of concentrated stator windings have a winding pitch of about 120* and each stator winding overlaps the adjacent stator windings by about 60*, and said rotor pole faces have a circumferential length of about 120*, whereby the brushless motor is suitable for stepped voltage wave shape energization.

3. A compatible brushless motor and motor control circuit comprising an annular stator member supporting a plurality of opposing pairs of concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relation to a rotatable ferromagnetic rotor, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, a motor control circuit comprising only a few controlled switches for applying simple substantially rectilinear wave shape energizing voltages of both polarities to said pairs of stator windings, the winding pitch and location relative to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing voltage applied by said motor control circuit, and control means responsive to the instantaneous position of said rotor for rendering conductive said controlled switches for desired intervals of conduction to energize said pairs of stator windings in a sequence to produce continuous torque to rotate said rotor in a given direction, wherein there are only three opposing pairs of series connected concentrated stator windings, said motor control circuit comprises a pair of alternately conducting controlled switches for each pair of stator windings, said controlled switches being solid state controlled devices, said three opposing pairs of concentrated stator windings are non-overlapping windings each having a winding pitch of about 60*, and said rotor pole faces have a circumferential length of about 120*, whereby the brushless motor is suitable for quasi-square voltage wave shape energization.

4. A compatible brushless motor and motor control circuit comprising an annular stator member supporting a plurality of opposing pairs of concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relation to a rotatable ferromagnetic rotor, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, a motor control circuit comprising only a few controlled switches for applying simple substantially rectilinear wave shape energizing voltages of both polarities to said pairs of stator windings, the winding pitch and location relative to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing voltage applied by said motor control circuit, and control means responsive to the instantaneous position of said rotor for rendering conductive said controlled switches for desired intervals of conduction to energize said pairs of stator windings in a sequence to produce continuous torque to rotate said rotor in a given direction, wherein there are only three opposing pairs of series connected concentrated stator windings, said motor control circuit comprises a pair of alternately conducting controlled switches for each pair of stator windings, said controlled switches being solid state controlled devices, said three opposing pairs of concentrated stator windings have a winding pitch of about 120* and each stator winding overlaps the adjacent stator windings by about 60*, and said rotor pole faces have a circumferential length of about 60*, whereby the brushless motor is suitable for quasi-square voltage wave shape energization.

5. A brushless motor suitable for energization by simple substantially rectilinear voltage wave shapes comprising an annular stator member supporting a plurality of opposing pairs of series connected concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relation to a ferromagnetic rotor mounted for rotation within said stator member, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, the winding pitch and location relativE to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce simple substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing rectilinear voltage wave shapes, wherein there are three opposing pairs of concentrated stator windings each having a winding pitch of about 90* and each stator winding overlaps the adjacent stator windings by about 30*, and said rotor pole faces have a circumferential length of about 90*, whereby the brushless motor is suitable for square voltage wave shape energization.

6. A brushless motor suitable for energization by simple substantially rectilinear voltage wave shapes comprising an annular stator member supporting a plurality of opposing pairs of series connected concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relation to a ferromagnetic rotor mounted for rotation within said stator member, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, the winding pitch and location relative to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce simple substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing rectilinear voltage wave shapes, wherein there are three opposing pairs of concentrated stator windings each having a winding pitch of about 120* and each stator winding overlaps the adjacent stator windings by about 60*, and said rotor pole faces have a circumferential length of about 120*, whereby the brushless motor is suitable for stepped wave energization.

7. A brushless motor suitable for energization by simple substantially rectilinear voltage wave shapes comprising an annular stator member supporting a plurality of opposing pairs of series connected concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relation to a ferromagnetic rotor mounted for rotation within said stator member, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, the winding pitch and location relative to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce simple substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing rectilinear voltage wave shapes, wherein there are three non-overlapping opposing pairs of concentrated stator windings each having a winding pitch of about 60*, and said rotor pole faces have a circumferential length of about 120*, whereby the brushless motor is suitable for quasi-square wave shape energization.

8. A brushless motor suitable for energization by simple substantially rectilinear voltage wave shapes comprising an annular stator member supporting a plurality of opposing pairs of series connected concentrated stator windings for generating magnetic fields of opposite polarity in torque producing relation to a ferromagnetic rotor mounted for rotation within said stator member, said stator member and rotor each having opposing arcuate pole faces to establish an approximately constant gap width therebetween, the winding pitch and location relative to one another of said concentrated stator windings, and the circumferential length of said rotor pole faces, having interdependent angular dimensions to produce simple substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave Shape as the energizing rectilinear voltage wave shapes, wherein there are three opposing pairs of concentrated stator windings each having a winding pitch of about 120* and each stator winding overlaps the adjacent stator windings by about 60*, and said rotor pole faces have a circumferential length of about 60*, whereby the brushless motor is suitable for quasi-square wave shape energization.

9. A compatible brushless motor and motor control circuit comprising an annular stator member supporting a plurality of symmetrically arranged opposing pairs of concentrated stator windings each simultaneously generating magnetic fields of opposite polarity in torque producing relation to a rotatable ferromagnetic rotor, said stator member and rotor having opposing arcuate pole faces to establish an approximately constant gap width therebetween, a motor control circuit comprising only a few controlled switches for applying simple substantially rectilinear stepped wave shape energizing voltages of both polarities to said pairs of stator windings, wherein the sum of the angular dimensions of the winding pitch of said concentrated stator windings and the circumferential length of one of said rotor pole faces totals approximately 240* and produces substantially rectilinear back emf voltages in each pair of stator windings that have approximately the same wave shape as the energizing voltage applied by said motor control circuit, and control means responsive to the instantaneous position of said rotor for rendering conductive said controlled switches for desired intervals of conduction to energize said pairs of stator windings in a sequence to produce continuous torque to rotate said rotor in a given direction.