Abstract
This paper proposes a generalized high-order observer for estimating total disturbance of permanent magnet synchronous motors (PMSMs). This total disturbance is dominated by load torque but also includes many other terms such as frictions, viscous force, Eddy and flux pulling forces, and noises. Comprehensive experimental results and analyses under various scenarios will be presented to find the appropriate order of the observer. We will compare the performance of zero-order observer (ZDO), first-order observer (FDO), and second-order observer (SDO) under three different scenarios of load torque. Additionally, the results of an state observer (ESO) under the same conditions are also presented. The experimental results show that FDO and SDO achieve similar performance and both of them are notably better than the ZDO and ESO. However, during the severe conditions of load torque, the SDO-based controller can achieve better performance compared to that of FDO-based controller. Moreover, fuzzy algorithm is applied to online tune the PI gains in the speed loop. The results also show that the SDO-based fuzzy-PI control scheme is effective in disturbance rejection and high-performance speed tracking. All of the experiments are carried out on a 300-W PMSM testbed with a digital signal processor (DSP).