Abstract: A pulse width modulated (PWM) trapezoidal commutation drive to a brushless direct current (BLDC) motor is sine modified so that the applied drive voltage substantially matches the induced voltage generated in the BLDC motor. The values of the cosine of the angles between ?30 degrees and +30 degrees are used to modify the duty cycle of the PWM drive signal dependent upon the rotor angular positions determined from the times between the zero crossing BEMF voltages measured at the unconnected motor terminals.

Abstract: A radial flux permanent magnet AC motor/generator employs a flat circular stator plate having a plurality of separately-formed electromagnets mounted in a ring pattern on a top surface thereof. A circular flux ring fabricated of powdered metal is mounted to the stator plate outside the ring of electromagnets. A plurality of permanent magnets are mounted in a ring pattern on the outer cylindrical surface of a steel rotor. The stator plate and rotor are axially and diametrically aligned such that the ring of permanent magnets rotates in close proximity to and inside the ring of electromagnets. The electromagnets utilize powder metal cores shaped to have rounded corners and flat sides that permit the use of heavier gauge windings and eliminate the air gaps that exist between the core and windings of prior art electromagnets.

Abstract: A brushless DC motor includes a rotor having an iron core affixed to a motor shaft. Permanent magnets are affixed to the core and separated by aluminum inserts which are keyed to the core. An annular groove in one end of the rotor core is dimensioned so that its outer diameter coincides with the inner tips of the aluminum inserts. The inner diameter of the groove and its depth provide only minimal clearance around commutation transistors which occupy the space within the groove. The commutation transistors are affixed and electrically connected to a circuit board which, in turn, is secured to the motor body by attachment to a removable motor end plate. With this structure, the commutation transistors are surrounded on three sides by the rotor and are triggered by its drive magnets. This structure permits the commutation transistor to be triggered by a strong magnetic flux which is more accurately directed through the transistor at its switch plane.

Abstract: 12-step motor commutation is provided by a three-phase sinusoidal signal generator and related circuitry. Circuitry which compares the voltage outputs of two primary signals provides two additional switching points for every 360 electrical degrees. Three comparator circuits provide six additional switching points. Primary voltage outputs are weighted in the ratio of 2:1 prior to comparison.

Abstract: A 12-step commutation in a brushless DC motor is achieved by six shaft-mounted commutation sensors and circuitry which permits inexpensive shaft-angle decoding for coil excitation. The commutation signal devices are Hall sensors arranged in two sets. A first set is arranged to produce the desired switching signals every 120 electrical degrees; a second set of three Hall sensors is similarly arranged equally spaced between the electrical switch points of the first set, however, the second set of sensors is wired together through the process of EXCLUSIVE-ORing to form a single, fourth output. Thus, the six Hall sensors are configured to produce four output signals which may be inexpensively decoded using a standard 32.times.8 PROM. A further refinement includes current modulation to the field coils in order to equalize the torque output of alternate steps.

Abstract: A coil unit for use in brushless and ironless armature motors which includes the form upon which the same is wound and providing, in its complete form, a self supporting coil unit which may be inserted into the laminations or soft iron shell of a motor.The complete coil unit includes a plurality of individual coils which are arranged in skewed, longitudinal, side-by-side relation to one another and the individual windings of the coils are positioned on both the inner and outer surfaces of the coil form, the inner and outer windings pairs being diametrically opposed to one another to thereby provide a pair of diametrically opposed coil portions which are connected in series aiding fashion.The coil form is a thin, longitudinally extending, tubular member of a non-magnetic material providing coil winding and locating cutouts or serrations on the longitudinal ends thereof.

Abstract: A stepper motor is provided with an adaptor ring for establishing the desired detent position of the motor shaft. The adaptor ring is rotated to a desired mounting hole alignment with respect to the shaft and then the ring is permanently secured to the motor housing.