CURRENT DETECTION SYSTEM FOR AC MACHINE

摘要

PURPOSE:To attain current detection reduced at its phase error up to low frequency by supplying a current signal based on a low frequency attenuation signal obtained by processing the low frequency attenuation of a current signal detected by a current detector and an AD current command signal compensated at its low frequency to an inverter. CONSTITUTION:A detecting signal outputted from the current detector 1 is turned to a low frequency attenuation signal through an HPF 3 and an AC current command signal i* is turned to a low frequency compensating signal through a low frequency compensator 4. Both the signals are supplied to an operational amplifier OP 3 and a current signal obtained by the operation is supplied to an inverter or the like as a current detecting value, so that current detection reduced at its phase error up to the low frequency can be attained without the influence of the offset or drift of the detector.