National Research Development Corporation

Peter John Lawrenson

Austin Hughes

An electric stepper motor has in addition to the usual driving coils at least one additional coil wound on its stator and connected in a closed circuit. This additional coil damps any oscillations of the rotor. The closed circuit has a resistive value optimized to achieve maximum damping effect. Two or more such additional coils may be connected in a single closed circuit and a number of such closed circuits may be provided.

Electric stepper motors

A stepper motor has impedance in series with each drive coil and the value of the impedance is changed during each drive pulse. Two different paths for current to a drive coil may be provided each having a different value of impedance and the current to the drive coil is switched between the two paths during each drive period.

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Leeds, United Kingdom

Peter John Lawrenson