The quality of pressure signals is intricately linked to the speed variation characteristics of the permanent magnet synchronous motor (PMSM) employed to drive the rotor of the continuous wave pulse generator. However, achieving precise control of PMSM is significantly challenged by complex and time-varying drilling operating conditions. A serialnADRC (SnADRC) is presented to increase the control motor's immunity and dynamic performance, where “n” indicates the number of sequential output stacking extended state observers (SOS-ESOs) equal to the highest order of the disturbance. Based on the deduced continuous wave pulse generator rotor model, first-order SOS-ESO is intended to detect the first-order disturbance, with the higher order SOS-ESO designed to anticipate the residual disturbances in order to accomplish real-time and precise hydraulic torque prediction. Moreover, the estimation performance of SOS-ESO is analyzed, and the intrinsic stability of SnADRC with the speed loop control system is rigorously demonstrated using the Lyapunov theory. Additionally, SOS-ESO is employed in simulation to resist polynomial disturbances, and it is discovered that thenthorder SOS-ESO may successfully suppress complex disturbances up to (n-1) order. Finally, the control performance of SnADRC is compared to that of classical control methods in both the simulation and experiment, and the results show that SnADRC has excellent rapidity and stability in motor control, which opens up a wide range of possibilities for practical applications in control and engineering fields.