Electronically commutated motor

A DC motor comprising a stationary armature comprising a core having a longitudinal axis and at least two different energizable windings each including concentrically disposed winding turns, the windings supported on said core to produce at least two spaced apart magnetic poles, a rotor having a predetermined number of constant polarity magnetic regions adapted to rotate about said longitudinal axis in response to magnetic fields established by said armature, commutation means for energizing said armature windings in a predetermined manner, at least two groups of winding turns each having a predetermined span of at least about 180 electrical degrees and wherein conductive turn segments in adjacent slots of the core arranged to carry current in the same relative axial direction have a predetermined spread less than 120 electrical degrees.

A brushless DC motor comprising a stationary armature having a core and at least two winding stages each comprising at least one effective winding, each winding comprising concentric winding turns accommodated by the core and arranged to produce a predetermined number of magnetic poles, a rotor adapted to rotate about said longitudinal axis in response to the magnetic poles established by said armature, and a commutation circuit for energizing the windings in a predetermined manner wherein said commutation circuit includes a detector circuit comprising:

• means responsive to the current drawn by the armature windings to provide an output signal indicative thereof, means for scaling the output signal by a factor corresponding to the resistance of the armature windings, means for substracting the resulting scaled signal from the voltage applied to the armature windings to provide a signal indicative of the back emf of the brushless DC motor, and wherein the commutation circuit further includes a frequency circuit means responsive to the back emf signal for generating a signal of a frequency proportional thereto indicative of the rotor speed and with said frequency circuit means having a minimum frequency output signal to aid starting of the brushless DC motor.

A commutation circuit for a brushless DC motor having a stationary armature with a longitudinal axis, a plurality of windings disposed on said armature to produce magnetic fields, a rotor adapted to rotate about said longitudinal axis in response to the magnetic fields established by the armature, said commutation circuit comprising:

• a detector circuit for sensing the current drawn through the armature windings and for scaling the sensed current signal in accordance with the resistance of the windings, for sensing voltage applied to the winding, and for generating an output signal indicative of rotor speed;
• an indexing means responsive to the detector circuit output signal for generating a plurality of output signals indicative of a relative position of said rotor with respect to said armature;
• an energizing circuit means responsive to said plurality of output signals from said indexing means for energizing said windings in a predetermined sequence in accordance with the relative position of said rotor.

A brushless DC motor having a stationary armature with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, a rotor adapted to rotate about a longitudinal axis in response to the magnetic fields, and a commutation circuit for controlling commutation of the windings wherein said commutation circuit comprises:

• a position circuit for simulating rotor position in accordance with the back emf condition of at least one winding;
• a circuit for energizing a selected one of the windings in accordance with the simulated rotor position;
• and an under speed protection circuit operable to prevent the circuit for energizing a selected one of the windings from energizing any of the windings when the motor speed is less than a predetermined minimum value for a predetermined length of time.

A brushless DC motor having a stationary armature with at least two different energizable windings disposed on said armature and energizable from a voltage source for producing spaced apart magnetic fields in time sequence, a rotor adapted to rotate about a longitudinal axis in response to the magnetic fields and a commutation circuit for controlling commutation of the windings wherein said commutation circuit comprises:

• a position circuit for simulating rotor position in accordance with the back emf condition of at least one winding;
• a circuit for energizing a selected one of the windings with power from the voltage source in accordance with the simulated rotor position;
• and an undervoltage protection circuit operable to prevent the circuit for energizing a selected one of the windings from energizing any of the windings when the voltage source output is less than a predetermined minimum value.

A brushless DC motor having a stationary armature with at least two different energizable windings disposed on said armature and energizable from a voltage source for producing spaced apart magnetic fields in time sequence, a rotor adapted to rotate about a longitudinal axis in response to the magnetic fields and a commutation circuit for controlling commutation of the windings wherein said commutation circuit comprises:

• a position circuit for simulating rotor position in accordance with the back emf condition of at least one winding;
• a circuit for energizing a selected one of the windings with power from the voltage source in accordance with the simulated rotor position;
• and an overvoltage circuit operable to prevent the circuit for energizing a selected one of the windings from energizing any of the windings when the voltage source output is greater than a predetermined maximum value.

A commutation circuit for a brushless DC motor having a stationary armature with at least two energizable windings disposed on said armature for producing spaced apart magnetic fields in time sequence, a rotor adapted to rotate about a longitudinal axis in response to the magnetic fields established by the armature and a commutation circuit for controlling commutation of the windings at a predetermined angle of advancement and wherein said commutation circuit includes means for aiding starting of the motor by generating a characteristic signal that is associated with an emf condition of the motor at low motor speed and wherein the characteristic signal is substantially less in magnitude than emf associated with the motor at full operating speed.

A DC motor comprising a stationary armature comprising a core having a longitudinal axis and at least two windings disposed on said core to produce differently directed magnetic fields, a rotor adapted to rotate about said longitudinal axis in response to magnetic fields established by said armature, means for providing signals indicative of the relative rotational position of said rotor, and circuit means responsive to said signals for energizing said stator windings in a predetermined sequence, said means for providing being operative to cause advancement of commutation of the windings by an angle alpha of from about five to about twenty-five electrical degrees to aid the build-up of current when the windings are energized during running condition, wherein said means for providing signals indicative of the relative rotational position of said rotor includes a detector circuit for sensing a back emf signal indicative of the back emf condition of at least one winding and a means responsive to the back emf signal from the detector circuit for integrating the emf signal to a predetermined value of volt-seconds and for producing said signal indicative of the relative rotational position of the rotor.