An Improved Fractional-Order Active Disturbance Rejection Control: Performance Analysis and Experiment Verification

This paper presents an improved active disturbance rejection control scheme (IFO-ADRC) with an improved fractional-order extended state observer (IFO-ESO). The structural information of the system is utilized in IFO-ESO rather than buried as in the typical fractional-order extended state observer (FO-ESO) and help significantly improve the performance of IFO-ESO and closed-loop system. Compared with the integer-order active disturbance rejection controller (IO-ADRC), the auxiliary tracking controller of IFO-ADRC has a simpler form and fewer parameters need to be tuned. Frequency-domain analysis shows that IFO-ESO has better performance over the larger frequency band than FO-ESO, and time-domain simulation shows that IFO-ADRC has better transient performance and is more robust against the parameter variations than traditional fractional-order active disturbance rejection controller (FO-ADRC) and IO-ADRC. The IFO-ADRC is applied to permanent magnet synchronous motor (PMSM) servo control system and demonstrates its capability in the real-world application.