Zero Speed Sensorless Control of Induction Motor with Ideal Voltage Source

In the speed sensorless control of the induction motor, the machine parameters (especially the rotoi resistance R₂) have a strong influence to the speed estimation. In addition, the output voltage error due to the dead time and the voltage drop of the inverter influence on the rotor flux estimation, but the simultaneous compensation of the output voltage and the stator resistance R₁is very difficult. In this paper the new algorithm of R₂estimation with utilizing only stator current is proposed. In the high frequency range, the R₂is estimated in the transient state, and in the very low frequency range, R₂is estimated in proportion to the estimated R₁when the ideal voltage source by the power op-amp is used instead of the voltage source inverter to avoid the output voltage error. In use of these algorithms, the low speed estimation was possible and the zero speed control was achieved under the 5~40% load condition in two motors. This paper clarified that the zero speed estimation is possible with the stator and rotor resistance estimations when the output voltage is ideal.