Measuring armature current in AC circuit of power converter - synchronously switching channels and measuring current through last commutated current path

摘要

The method involves coding and switching the voltage drops across the apparent ohmic resistances via two analogue multiplexers (MUX1, 2) into the commutation sequence for right and left rotating fields of the network, in dependence on the direct control signal and the control signal for double ignition signals. A signal dependent on the rotation direction of the network is used for selecting one of the two multiplexers. ADVANTAGE - Current through last commutated current path is measured and magnetising currents do not influence high accuracy zero current measurement.