An Improved Third-Order Generalized Integral Flux Observer for Sensorless Drive of PMSMs

Abstract

Due to various nonideal factors, including integral initial value, parameter mismatches, converter nonlinearities, and detection errors, the estimated rotor flux by the conventional first-order integrator and low-pass filter suffers the dc offset and harmonics. Recently, a second-order generalized integral flux observer is proposed to reduce the dc and high-order components in the rotor flux. However, it has limited attenuation ability against the dc offset. This paper proposes an improved third-order generalized integral flux observer (TOGIFO). As shown by theoretical analysis, it can effectively eliminate the dc and high-order components in the estimated rotor flux without any negative effect on the amplitude and phase angle of the fundamental waveform. The rotor position and speed can then be extracted directly from the estimated rotor flux. The sensorless drive method based on TOGIFO is implemented and verified through comprehensive numerical simulation and experimental testing on a permanent magnet synchronous machine drive platform controlled by a TMS320F28335 digital signal processor.