［Objective］ To improve the disturbance rejection capability of the deadbeat predictive current control (DPCC) system for permanent magnet synchronous motors (PMSM)

a secondorder enhanced extended state observer (SEESO) is proposed to overcome the performance limitations of traditional linear extended state observers (LESO) under rapid timevarying disturbances and highfrequency harmonics. ［Methods］ First

the 6k harmonic model caused by inverter nonlinearity and the magnetic flux of the permanent magnet was derived

and the mathematical model for DPCC was established. Then

the impact of parameter disturbances on the dynamic and steadystate control performance of DPCC was analyzed in terms of speed

stability

and accuracy. Next

the SEESO model was constructed

and its stability and the differences in disturbance and disturbance error observations compared with the traditional extended state observer were theoretically verified. Furthermore

the final value theorem was used to demonstrate that the SEESO could achieve zero steadystate error observation of timevarying disturbances

in contrast to LESO. ［Results］ Finally

the feasibility and advantages of the proposed control strategy were verified through Matlab/Simulink simulation software. Specifically

SEESO effectively reduced tracking errors and quickly stabilized under dynamic load disturbances. Additionally

the sixth harmonic in steadystate conditions was significantly reduced

improving the system’s resistance to harmonics. SEESO also demonstrated higher estimation accuracy and faster response speed under steadystate parameter disturbances

thus improving the system’s robustness to parameter variations. ［Conclusion］ The results show that SEESO can effectively enhance the disturbance rejection capability of DPCC

providing an effective solution for improving the disturbance rejection capability of motor drive systems.