Efficient Precision Current Regulator for High-Power Magnets

Abstract

Using paralleled power transistors driven by a transistor and a chopper amplifier, supplemented by a coarse feedback loop to the generator field, we have regulated to <0.001% the field of an electromagnet requiring 80 amp at 200 v. The dissipation in the regulator is 250 w. The magnet current may be varied from zero to maximum by setting the reference potentiometer to the appropriate voltage, and sufficient protective measures are incorporated so that the circuit is not injured by misuse. The circuit is usable to perhaps a megawatt.