Unified Adaptive Flux Observer for AC Machines

This work develops a novel unified observer for flux estimation in ac machines. It has been demonstrated that a unified adaptive flux observer based on the active flux concept can be implemented for both Permanent Magnet Synchronous Machines (PMSMs) and Induction Machines (IMs). Using the well-known “Voltage Model” (VM) in addition to the modified “Current Model” (CM), a full-order adaptive flux observer can be designed. This unified state observer is essentially the same for all ac machines, in which only the stator resistance and equivalent inductance are needed. The stability conditions of this novel flux observer scheme based on the proposed model have been derived analytically using the Lyapunov theory. Digital simulations in MATLAB/Simulink are given to illustrate the theoretical results for both PMSMs and IMs. Finally, experimental tests were done on both IMs and PMSMs to validate the proposed unified observer's performance.