Thesis title: MECHANICAL FLUX WEAKENING IN A SPLIT ROTOR PERMANENT MAGNET MACHINE FOR A VERY WIDE CONSTANT POWER SPEED RANGE
This Ph.D. thesis presents an innovative machine solution for mechanical flux weakening (MFW), consisting in a split rotor (SR) radial flux surface permanent magnet (SPM) machine, in which MFW is achieved through the phase shifting of the rotor sections, using an internal electromagnetic shifting torque, produced through the d-axis current, without any external device. The analysis and the FEA results demonstrate that the proposed SR machine with MFW could maintain a constant line to line voltage throughout a 10:1 CPSR, at the expense of a very small decrease in the torque density compared to the traditional SPM machine with EFW. The experimental results confirm the FEA findings. In particular, the line voltage stays essentially constant throughout a CPSR of at least 3:1. For limitations of the test bench it was not possible to increase the speed beyond the 3:1 range. Nonetheless, it is expected that the real CPSR, throughout which the line voltage stays constant, would be much wider.