Current-Sampling Transformer Circuit
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
A current-sampling transformer circuit is described for use with a bridge-driven motor. The transformer is pulsed at high frequency, gives high voltage isolation between a sensing circuit and the motor drive circuit, and senses both DC and AC motor current. A current source is pulsed into the primary of the transformer, and the secondary of the transformer is connected through a diode to a sensing resistor through which the motor current passes. Two applications of this circuit are described to prevent motor-switching transients affecting the accuracy of DC measurement or damaging the transformer: the first injects current into the primary and the second shorts the primary both during the off period of motor drive. Fig.