Parameter extraction for three phase IPM machines through simple torque tests

This paper presents a method for obtaining the main parameters, such as the torque constant and the d- and q-axis inductances Ld and Lq, for a brushless internal permanent magnet motor by measuring the machine torque during testing. These tests are relatively simple to carry out compared to other test procedures described in the literature and do not require sophisticated equipment. The machine under test is supplied through a dc supply at different rotor positions. The shaft torque is measured through a torque sensor during the tests. The test current is varied to take care of the saturation effects. From the measured torque data and known rotor position, the required parameters can be obtained. Tests performed on two different internal permanent magnet machines confirm the validity and effectiveness of the proposed technique.