Abstract: A permanent magnet direct current machine is provided. The rotor has permanent magnets acting as poles for feeding magnetic flux to the stator. The stator has a multiplicity of "slot paths". Each slot path has as many slots as there are poles on the rotor and also has as many coils as there are poles on the rotor. The coils of a slot path are equally spaced around the axis of the machine and each coil of the slot path is wound through two slots. The coils of a slot path may be switched from series to parallel to hybrid relationships to vary the operating characteristics of the machine.

Abstract: This PMDC machine concept operates from a constant dc voltage source with maximum torque capacity throughout its rotational speed range. The back electromotive force (back-emf) produced by the machine windings under the constant amplitude air gap field produced by the magnets is controlled by changing the winding configurations in series-parallel combinations. Torque is, thus, controlled from minimum to maximum speed without exceeding winding current capacities and without need to increase driving voltage with speed. At startup and low speed the combined back-emf of series connected windings limit current while producing maximum torque. At higher speeds where back-emf would severely limit torque, the windings are connected in series-parallel combinations for maximum achievable torque without exceeding winding current capacities. To accomplish this, windings concentrated in slots are used. Result is optimum utilization of core magnetics and capability of operating at constant input voltage.

Abstract: Apparatus may be inserted in the casing of a d.c. motor or a d.c. generator for measuring not only the magnetic fields prevailing in the machine but developing other useful information. The magnetic fields between the field poles and the armature, and also the armature/mmf fields aligned with the brushes may be measured. The measurements of the fields permits a complete plot of the fields in the machine and also permits a test to be performed to see if the brushes are at their optimum positions. If a brush is not at its optimum position, the brush may be shifted back and forth until the maximum mmf, due to the current through the armature is aligned midway between the leading and trailing ends of the brush area coverage on the commutator.