Design Of The Asynchronous Motor Speed Sensorless Control System Based On Internal Model Technology

The asynchronous motor is a multivariable, strongly coupled non-linear object.There is a coupling voltage after the vector transform according to the rotor fieldorientation, so decoupling measures needed. The inverter’s dead time will cause theoutput voltage deviation, the torque ripple and instability. Therefore, the dead timerequired to be compensated. The speed sensor is not suitable for many environments,and therefore sought a simple, stable and reliable control without speed sensor is ofgreat significance. This paper is to study the asynchronous motor sensorless vectorcontrol system, including asynchronous electric decoupling control strategy, theinverter dead time compensation and speed sensorless.Firstly, in order to solve the problem of voltage coupling of asynchronousmotor after vector transformed, a new internal model decoupling to achieve thedecoupling of the excitation component and torque component of stator current, andthe feedback decoupling strategy is simulated and comparative analysis. Theinternal model control is not dependent on the accuracy of mathematical models, caneffectively suppress the impact of the motor parameter variations on decoupling andstrong robustness.Secondly, the internal model control is applied in the speed control system, andtwo degrees of freedom of the model control is simulated and analysis toindependently regulate tracking performance and anti-jamming capability, andachieved a good control performance. The disturbance rejection method and theequivalent input disturbance of thought are utilized to improve two degrees offreedom internal control model, which use to compensate for the deviation of thevoltage and current distortion caused by dead time of inverter. This method reducedthe electromagnetic torque fluctuation and enhanced system stability.Finally, the conventional model reference adaptive speed estimation method hasa problem of integrating initial error. This paper analysis and research the pro blem,improved MRAS speed estimation method using the inverse voltage model. Theintegral transform into the differential, achieved a more high-precision speedtracking.