Flux Observer with Adaptive Parameter Based on Dual Third-Order Generalized Integrator Frequency-Locked Loop

The flux-estimation model employs a third-order generalized integrator frequency-locked loop to effectively eliminate DC bias. However, this method has two limitations. First, the frequency estimation performed by the frequency-locked loop (FLL) can sometimes be inaccurate at times, resulting in frequency oscillations when the EMF fluctuates, impacting the dynamic performance of the method. Second, the method has restricted capability when it some to suppressing high harmonics. To address the disadvantages of the dynamic performance, a more advanced method called dual TOFO-FLL (DTOFO-FLL) is proposed to improve the dynamic response. Furthermore, the coefficient k of the generalized integrator is crucial for both harmonic suppression and dynamic performance. In an effort to improve the suppression of high-order harmonics, while maintaining a robust dynamic performance, a flux-observer parameter adaptive method, DATOFO-FLL, is brought forth based on DTOFO-FLL. A theoretical analysis demonstrates that this technique delivers strong harmonic suppression during steady-state operation and upgraded dynamic performance in terms of response speed and disturbance rejection. Experimental validation was conducted on a platform controlled by an STM32G431RB digital signal processor to test a sensorless drive method using DATOFO-FLL. The results verified the effectiveness of this approach in driving a permanent magnet synchronous motor.