Sensorless speed observer for industrial drives based induction motors with low complexity

This chapter presents a simple method to efficiently predict the rotor speed for a sensorless vector control technique applied to induction motors (IMs). The motor is supplied by a Simplified Split-Source Inverter (S3I), which provides dc-boosting and ac-inversion processes during input voltage sag. It also has a wider modulation range and a lower harmonic content than conventional boosting inverters. With this contribution, it is possible to efficiently estimate the rotor position directly without needing a PI controller with fluctuated supply voltage. The proposed strategy can be divided into three parts. The first uses a dual-loop controller to obtain the reference DC-boosted voltage of the SSI and regulate the input current. The second is the suggested observer for speed detection, which is derived from the principles of phase axis relations of the adopted machine currents and the indirect rotor flux orientation control (IRFOC) approach. With a newly developed space vector modulation, the third part will generate the switching pulses of the inverter switches. A complete analysis has been conducted to ensure the observability of the proposed technique. A series of PLECS simulations were conducted to verify the concept. The obtained results validate the proposed strategy with the S3I topology.