Position sensorless synchronous reluctance motor drive using the stator phase voltage third harmonic

A direct field orientation controller for synchronous reluctance motors based on determination of the spiral position of the air gap flux from the third harmonic component of the stator phase voltages is presented. The control utilizes the spatial saturation harmonic components rotating at synchronous frequency that are generated in the air gap flux when the machine operates in a saturated condition. When the machine is wye connected, the sum of three-phase voltages results in a signal dominated by the third harmonic component. Using this signal, a completely sensorless drive is implemented which can successfully synchronously start the reluctance motor from zero speed. Extensive experimental results showing the effect of different estimation schemes and practical problems of detecting the flux position from the harmonic voltage signal are presented.<
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