Derivation of motor line-current waveforms from the DC-link current of an inverter

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Abstract
A technique for reconstructing motor line currents using information from a single current transducer in the DC-link of an inverter is presented. All the instantaneous motor line currents can be reconstructed with a bandwidth limited to half the inverter switching frequency. These waveforms are used to produce a highbandwidth signal, proportional to the scalar magnitude of the line current, and which is suitable for motor control purposes. A simple, low-cost implementation of the scheme demonstrates accurate results in a practical motor drive.