A Polar-Coordinate-Multisignal-Flux-Observer-Based PMSM Non-PLL Sensorless Control

Abstract

In this letter, a polar-coordinate-multi-signal- flux-observer (PCMFO) is proposed for PMSM sensorless control. PCMFO is constructed in polar coordinate and uses the orthogonality relations between αβ-axis active flux. It permits estimating the rotor position and the flux simultaneously, instead of obtaining the active flux first and then the rotor position, so the phase-locked loop (PLL) is not necessary. Furthermore, PCMFO consists of paralleled multiple observers which respectively estimate the dc bias, fundamental wave and harmonics, thus eliminating the influence of these interfering signals on flux estimation. The theoretical analysis indicates PCMFO can reduce the system order, and suppress the estimation error caused by rotor speed varying and discretization. Then the PMSM sensorless control is constructed based on it. The experimental results verify the superiority of this method.