Speed-Sensorless Control of Pole Transition for Variable Phase-Pole Induction Machines

Variable phase-pole induction machines appear to offer the potential for use in electromobility applications due to their capability of electronically changing the number of magnetic poles, thus extending the torque-speed operation of the machine. This work presents a model reference adaptive system solution for the sensorless speed operation of a nine-phase variable phase-pole induction machine. The same adaptive fullorder observer is used to estimate the mechanical speed in two different ways, one for each pole pair configuration of interest. The sensorless operation of the drive is maintained during the pole-pair configuration change with a suitable transition between the two speed-estimation laws, guaranteeing precise rotor flux linkage information for achieving high-performance control. The simulation and experimental results of the proposed method demonstrate a high degree of agreement, indicating the effectiveness of the proposed sensorless methodology under varying load conditions and positive/negative speed transitions.