This PMDC machine concept operates from a constant dc voltage source (30) with maximum torque capacity throughout its rotational speed range. The back electromotive force (back-emf) produced by the machine windings (21) under the constant amplitude air gap (12) field produced by the magnets (15) is controlled by changing the winding configurations in series-parallel combinations (Figs. 3A and 3B). Torque is, thus, controlled from minimum to maximum speed without exceeding winding current capacities and without need to increase driving voltage with speed. A startup and low speed the combined back-emf of series connected windings (21) 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 (21) concentrated in slots (17) are used. Result is optimum utilization of core magnetics and capability of operating at constant input voltage.