Abstract: A method for field weakening control of a three phase permanent magnet AC motor in a VFD drive. The VFD drive calculates the three phase voltages to be supplied to the AC motor via a three phase inverter using feedback and feed-forward calculations of quadrature and direct demand currents.

Abstract: Multiple methods and corresponding apparatuses for efficient and reliable defect diagnosis in components of mechanical systems, are described. According to one aspect, multi-scale enveloping-order spectrogram is used to diagnose, or detect, defects in a moving component of a mechanical system. According to another aspect, defect identification and diagnosis in a motor is performed based on spectral characteristics of motor current envelope. According to yet another aspect, a logic rule model, employing classification of features associated with single- or multi-sensor data, is employed for diagnosis of defects in components of mechanical systems.