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

In this letter, a polar-coordinate-multi-signal-flux-observer (PCMFO) is proposed for permanent magnet synchronous motor (PMSM) sensorless control. PCMFO is constructed in polar coordinates and uses the orthogonality relations between
αβ
-axis active fluxes. 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 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 that PCMFO can reduce the system order and suppress the estimation error caused by the varying rotor speed and discretization. Then, the PMSM sensorless control is constructed based on it. The experimental results verify the superiority of this method.