[Objective] To address the issues of speed fluctuation, additional load disturbance, and insufficient driving robustness in airport roller serpentine conveyor vehicles during large-inclination ramp conveying, this paper takes a single electric drum drive unit as the object and proposes a composite anti-disturbance control method based on parameter scheduling and feedforward-observer for permanent magnet synchronous motor (PMSM). [Methods] Firstly, the medium-speed operating condition was determined based on the drum diameter and the engineering conveying speed range, and a vector control model for the single-drum PMSM was established. Secondly, an equivalent ramp load model related to the slope angle was constructed, and the proportional-integral (PI) parameters of the speed loop were designed with the slope angle θ as the scheduling variable, enabling the controller gain to be adaptively adjusted with the inclination angle. Then, the calculable ramp load was compensated into the q-axis current command through gravity feedforward to reduce the feedback regulation pressure on the speed loop. Finally, for the unknown additional disturbances remaining after feedforward compensation, a residual compensation structure of a direction-adaptive sliding mode disturbance observer (SMDO) was constructed, and effective q-axis compensation current was generated through disturbance estimation bias correction, slope-direction gain adjustment, and compensation current limiting. [Results] The simulation results indicated that under the variable-inclination conditions of 0°→8°→16°→24° uphill and 0°→-8°→-16°→-24° downhill, the maximum speed deviation was reduced by the parameter-scheduled field-oriented control (FOC) compared with the fixed-parameter FOC, and the improvement became more obvious with the increase of the inclination angle. Under the condition of ±24° ramp, the speed deviation was significantly decreased and the output burden of the speed loop PI was greatly reduced by the gravity feedforward. When unknown additional disturbances were superimposed, the speed drop under uphill resistance disturbance and the speed overshoot under downhill assistance disturbance were respectively reduced by the direction-adaptive SMDO residual compensation. [Conclusion] The proposed composite anti-disturbance control method based on parameter scheduling and feedforward-observer improves the speed maintenance capability of the single-drum drive unit under variable-inclination angles and additional disturbances, and provides an executive-layer control foundation for subsequent research on multi-drum coordinated control.