Power supply for a stepping motor

Claim 1

A power supply for producing a rotating magnetic field in a stepping motor stator comprising: a stepping motor having a stator and a rotor, the stator having a plurality of independently energizable windings arranged in a star configuration with each winding connected to a neutral, a single polarity direct current source connectable for independently energizing each of said windings and operative when connected to a winding to supply current through the winding and the neutral, said source having an individual triggerable rectifying element for each of said windings, each of said triggerable elements comprising a plurality of groups of silicon controlled rectifiers each having first, second and third electrodes, the first electrodes of each individual group of rectifiers being connected in common for accepting a gating control signal for rendering the rectifiers conductive, the second electrodes of each group of rectifiers being independently connectable to an alternating current power source and the third electrodes of each group of rectifiers being connected in common to a corresponding winding for supplying the direct current to the winding upon conduction of the rectifier, a multi-phase alternating current source having each phase independently connected to one of the second electrodes in each group of rectifying elements, controllable means for independently supplying gating control signals to the first electrodes of each group of rectifying elements, and program means constructed and defined for controlling the controllable means to supply the gating control signals to the first electrodes within each rectifying element group in a preselected sequence in accordance with the selected program and independent of the position of the motor rotor so as to cause the energization and de-energization of the multi-phase windings in a step-by-step fashion and thereby to cause the generation of a rotating magnetic field for producing the rotation of the rotor in 15 mechanical degree increments, the application of a gating control signal to said first electrodes of each group of rectifying elements causing the conduction of said rectifying elements upon the substantially simultaneous occurrence of the positive half cycles of the alternating current voltage applied to said second electrodes of said rectifying elements from said alternating current source while the occurrence of the negative half cycles of the alternating current voltage applied to said second electrodes maintain the rectifying elements non-conductive and/or render the rectifying elements non-conductive, whereby any external disturbances causing a non-conductive element to be triggered to a conductive condition not in accordance with the selected program will be conductive only for the remaining duration of the positive half cycle of the alternating current.