Fractional-order system identification and proportional-derivative control of a solid-core magnetic bearing

This paper presents the application of fractional-order system identification (FOSI) and proportional-derivative (PD^μ) control to a solid-core magnetic bearing (MB). A practical strategy for closed-loop incommensurate FOSI along with a modified error criterion is utilized to model the MB system and a corresponding, verification experiment is carried out. Based on the identified model, integer-order (IO) PD and fractional-order (FO) PD^μ controllers are designed and compared with the same specifications. Besides, the relation between the two categories of controllers is discussed by their feasible control zones. Final simulation and experimental results show that the FO PD^μ controller can significantly improve the transient and steady-state performance of the MB system comparing with the IO PD controller.