Position Sensorless Control Strategy Based on an Enhanced High Order Generalized Integrator Flux Observer for PMSM Drives

Abstract

In the position sensorless control area of permanent magnet synchronous motor (PMSM), compared with back electromotive force method, the flux observer can realize a wider operating range because it is decoupled from speed. However, the traditional flux observer will bring about both dc bias problems caused by voltage or current detection error, and harmonics problems caused by converter nonlinearities, ultimately, these problems will significantly increase the position estimation error. Thus, an enhanced high-order generalized integrator flux observer (HOGIFO) method is proposed to obliterate the dc bias and substantially suppress the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$5{\text{th}}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$7{\text{th}}$</tex-math></inline-formula> harmonics on the estimation of active flux. Meanwhile, the stability is analyzed and the parameters tuning is also discussed for the HOGIFO. In addition, for improving the resonant frequency estimation performance, the double-axes involved frequency-locked loop is designed, it could achieve more accurate frequency tracking during dynamic process. Then, in order to facilitate engineering implementation, the S-domain transfer function of HOGIFO is discretized to the Z-domain. Finally, the validity of the proposed HOGIFO is verified by experiments on a 1.0-kW PMSM drive platform.