V-Type Sensorless Field Oriented Control of Induction Motors for Low Cost Applications

The paper presents a simple sensorless field oriented control (FOC) for an induction motor drive. The control algorithm is derived from the conventional FOC equations by successive approximations. The control is of the so-called V-type, that is, the references to the voltage inverter are calculated, instead of derived as outputs of the current regulation loops. The problem of the steady state instability, which arises in V-type control, is analysed first, then successful fixed by a proper filtering of stator current measurements. The result is a precise, reliable and low-cost induction motor drive. Implementation hints and experimental results are included in the paper.