Improved Position-Offset Based Online Parameter Estimation of PMSMs Under Constant and Variable Speed Operations

This paper proposes an improved position-offset based parameter estimation (POPE) method for permanent magnet synchronous machines. In the proposed method, dq-axis inductances and permanent magnet flux linkage can be estimated simultaneously based on three machine states corresponding to injections of zero, positive, and negative position offsets. The guideline is also provided for selecting appropriate amplitude of injected position offset. Compared with the conventional POPE methods, the proposed method has two distinguished advantages, i.e., (a) the influence of inverter nonlinearity can be fully eliminated and (b) the proposed method can be applied under both constant and variable speed operations. The effectiveness of the proposed parameter estimation method is verified by simulations and experiments.