Direct field orientation controller using the stator phase voltage third harmonic

A novel direct field orientation controller for induction machines based on the determination of the spatial position of the air gap flux from the third-harmonic component of the stator phase voltages is presented. The control utilizes spatial saturation harmonic components rotating at synchronous frequency which are generated in the air gap flux when the machine operates in a saturated condition. When the machine is wye connected, the sum of the three phase voltages results in a signal dominated by the third harmonic and a high-frequency component due to the rotor slot ripple. Extensive experimental results showing field-oriented operation of an induction machine are presented.<<ETX>>