Rotor Flux Amplitude Estimation Method Using D-filter with Adaptive Identifier of d- and q-Inductances for Rotor Magnet Temperature Estimation in Permanent-Magnet Synchronous Motors

Abstract

An important issue in permanent-magnet synchronous motors (PMSMs) for electric vehicle (EV) traction is estimating the temperature of the rotor permanent-magnet in real-time. This paper proposes a novel rotor flux-amplitude estimation method to enable real-time rotor magnet temperature estimation of the PMSM without flux dq-cross coupling. The proposed method has the following features: (a) A minimum-order D-flux state observer, included in the D-filter, is used for the real-time estimation of the rotor flux-amplitude. (b) The d- and q-inductances required by the observer are estimated using an adaptive parameter identifier. (c) The adverse effects caused by the current detection offset on the flux-amplitude estimate and identified inductances are overcome by utilizing the characteristics unique to each system. (d) The instability caused by the coupling of two real-time systems is addressed by adopting a special structure that prevents such instability. (e) Using the proposed method, the real value of the rotor flux-amplitude can be estimated in 0.9s after the zero initial-state start.