Variable flux, DC bus voltage control, and self-sensing for flux intensifying IPMSM

Having good dynamic performance, power conversion properties, and a low cost are always goals for every drive system. This research follows these goals as motivation and focuses on control methods for FI type PM machine drives. Several approaches are investigated to achieve these goals. First, injection signals selections, effects of DC bus voltage, and control methods for FI-IPMSM are explored to improve the position self-sensing accuracy and drive reliability. Secondly, it is shown that reducing DC bus voltage used during low speed condition will improve inverter efficiency and self-sensing performance. However, the required DC bus voltage value is difficult to calculate precisely due to machine parameter estimation errors and spatial harmonics. An online optimum DC bus voltage calculation is proposed to solve these issues while achieving energy savings. Finally, this research also focuses on control methods of VFI-IPMSM: flux manipulation methods, MS selection methods to achieve energy savings and MS estimation. The conventional MS manipulation methods cause pulsating torque or require lookup tables, which rely on time consuming experiments. New control methods featuring relatively low sensitivity to parameter estimation errors and smooth torque control during magnetization manipulation are presented. A MS manipulation method to achieve loss savings is proposed and the VF machine is shown to have a better loss saving properties compared to a commercial IPM machine. The MS information is shown to be the key for properly selecting the MS to achieve energy savings. A new MS self-sensing methodology is proposed by using high frequency injection and achieves reliable MS estimation. Ultimately, energy savings are achieved by properly manipulating MS with the correct MS estimation information.