A speed-sensorless IM drive with modified decoupling control

The popular speed-sensorless drive of current-controlled type has several disadvantages. It needs a current loop of high bandwidth which causes complexity in the implementation hardware/software, and requires a dedicated high speed DSP. The structure of speed-sensorless inverters is also not compatible with the general purpose V/F inverters of voltage type. To overcome such problems, we develop a new sensorless drive based on decoupling control and an adaptive full-order observer. Our new sensorless drive differs from the existing sensorless drive in the following points: (i) speed estimation is based on rigorous control theory, and is well analyzed, (ii) a modified decoupling control is introduced with which the torque control performance is improved, and (iii) decoupling control is integrated with the adaptive observer to reduce complexity of the whole system.