Automatic IM parameter measurement under sensorless field-oriented control

A novel approach of automatic induction motor (IM) parameter measurement under sensorless field-oriented control (FOC) is presented. No additional hardware is required in this approach. Before start-up, the inverter drive automatically performs the DC test, the no-load test and the locked-rotor test for the driven IM. Only input current signals are measured and sent to the field-oriented controller. The concepts of no-load test and DC test can be modified under the FOC structure. The conventional locked-rotor test requires that the rotor shaft has to be locked mechanically. This prohibits automatic measurement by the FOC inverter drive. A pseudo locked-rotor test for FOC structure is presented in this paper to facilitate automatic IM measurement. The test data are then computed to get the IM parameters and the exciting current command for FOC. The presented method has been tested on a 3-HP inverter-driven motor system. Its effectiveness is illustrated by experimental recordings.