Identification Technique for Exponents and Current Source of Polynomial Flux Saturation Model for Synchronous Motors

Abstract

This article proposes a parameter estimation technique for a self-saturation model of synchronous motors. The standstill self-identification method requires an equation-based flux saturation model for flux saturation modeling. The selected self-saturation model has the form of a polynomial representing a current with respect to a magnetic flux. This flux saturation model contains unknown parameters, including exponents, coefficients, and a current source for a permanent magnet. The exponent is a crucial parameter representing the nonlinear current and magnetic flux relationship. Therefore, the estimated flux saturation model only represents the flux saturation well if an appropriate exponent is selected. The proposed method can estimate the exponent of the self-saturation model for synchronous reluctance motors (SynRMs) using a linear least squares method (LSM). In addition, parameters of the self-saturation model for permanent magnet synchronous motors (PMSMs), including the exponents and a constant current source, can be estimated simultaneously. The rest of the coefficients of the flux saturation model are estimated using a linear LSM based on the pre-estimated exponents and a constant current source. The proposed parameter estimation method can be implemented in embedded systems. The performance of the proposed parameter estimation method was verified in 1.5-kW SynRM and 11-kW interior PMSM.