Dynamic motor parameter identification for high speed flux weakening operation of brushless permanent magnet synchronous machines

An experimental investigation is conducted to determine the behaviour of brushless PM synchronous machine parameters in the high speed flux weakening operating range. Real-time operating characteristics are determined for two commercially available 4 Nm interior PM synchronous machines. Special computer assisted measuring techniques are employed using an experimental vector controlled drive, capable of providing sinusoidal excitation waveforms at up to 8000 RPM. Perturbation analysis is performed on the measured data and results are applied to a variation of the classical d-q axis equivalent circuit model. The experimental results are repeatable and show a significant variation in the machine parameters as a function of the torque angle. Magnetic nonlinearities are also identified and accounted for through recomputation of the machine model over a wide range of operating points. The authors demonstrate that all tests can be performed with no previous knowledge of manufacturer proprietary information or results from finite element simulation.