Abstract: A vacuum cleaner assembly includes a motor having a rotor and a stator for providing motive power to the assembly. The rotor and stator each include armatures having tips. In one aspect, the widths of the rotor and stator tips are different. In another aspect, the rotor armatures have a non-constant width. Another aspect discloses the motor being a two-phase brushless motor having an even number (N) of stator armatures and N+2 rotor armatures. In another aspect, a rotor armature includes an aperture. In another aspect, each rotor armature includes a plurality of layers laminated together, with one layer being dimensionally different than the other layers. In another embodiment of the present invention, a control circuit energizes the windings of the stator so as to toggle the rotor in a first direction before alternately energizing the windings to drive the rotor in a second direction.

Abstract: A vacuum cleaner assembly includes a motor having a rotor and a stator for providing motive power to the assembly. The rotor and stator each include armatures having tips. In one aspect, the widths of the rotor and stator tips are different. In another aspect, the rotor armatures have a non-constant width. Another aspect discloses the motor being a two-phase brushless motor having an even number (N) of stator armatures and N+2 rotor armatures. In another aspect, a rotor armature includes an aperture. In another aspect, each rotor armature includes a plurality of layers laminated together, with one layer being dimensionally different than the other layers. In another embodiment of the present invention, a control circuit energizes the windings of the stator so as to toggle the rotor in a first direction before alternately energizing the windings to drive the rotor in a second direction.

Abstract: An apparatus for controlling the speed of rotation of the rotor of a brushless DC motor wherein means are provided for shifting both the on and off angle of motor excitation in opposite senses to thereby widen or narrow the pulse of energization to motor winding(s).

Abstract: A rotor position determination system for a polyphase D.C. brushless motor utilizing the back electromotive force (B.E.M.F.) voltage of the open or "off" phase of the motor as a critical signal for controlling the commutation of the motor, the system further including means for phase advance of the energization of the motor.

Abstract: A method and apparatus for the sensorless determination of commutation position in a brushless motor. The electric current flowing within the active, or energized, stator coil during energization is differentiated to produce a current rate of change waveform. The current rate of change waveform is compared to a predetermined voltage threshold which is set to approximate the point at which the rotor is in direct positional alignment with the active stator. From this comparison, it is determined when the current rate of change waveform fails to intersect the predetermined voltage threshold. This information may be used to commutate the application of a driving signal to the next stator coil in succession to maintain continuous torque on the rotor. This information may also be indicative of a stalled condition, in which case a stall indicator is triggered to alert the user of the stalled condition.

Abstract: Control circuits for operating electric motors of the class having windings pulsed in sequence and a magnetic field, the class being exemplified by brushless d.c. motors. Improved apparatus is provided for accommodating flyback action when excitation current through any one of the windings is interrupted by the opening of a switch device (e.g., on-off controlled transistor), whether that device be a sequence power switch or a main switch having a common series relation to all of the power switches and operated with an adjustable duty cycle so as to permit adjustment of motor speed and torque. The flyback apparatus, as here disclosed, provides low loss flyback current paths so as to return inductively stored energy back into the winding when its excitation is interrupted, thereby to enhance motor efficiency while eliminating high open circuit voltages across the switching devices. Negative torque which might be created in the flyback circuits as a result of back e.m.f.