Control of a split rotor SPM synchronous machine for very wide flux weakening operations

This article proposes a suitable controller for the mechanical flux weakening solution based on a split rotor SPM machine. In this machine configuration, the rotor is split in two independent sections which can rotate one with respect to the other to regulate the amount of permanent magnet flux linkage. The shifting torque to enable the relative rotor motion is generated inside the machine, through the d-axis current, without the use of any external actuator.The machine mathematical model is discussed to describe how the rotors angle affects the electromagnetic model and to introduce the relationship between d-axis current and rotors' shifting angle. A modified version of the standard current controller is proposed, according to the obtained electromagnetic model. In addition, a regulator based on feedback linearization is proposed to control the rotors' shifting angle dynamics. To conclude, a simple model based open loop flux weakening strategy is developed. The theoretical analysis is supported by simulation results.