Large speed fluctuations, low rotor position estimation accuracy, and insufficient anti-disturbance capabilities exist in motor drive systems under external disturbances. A composite control strategy was proposed. It combined a time-varying integral terminal sliding mode controller with an adaptive phase-locked loop. A dynamic coupling mechanism was constructed. A time-varying gain nonlinear reaching law and a fast integral terminal sliding mode surface were used. Chattering was suppressed. Exponential convergence of the response speed was achieved. A sliding mode disturbance observer was designed for external load disturbances. Hierarchical disturbance compensation characteristics were included. The dynamic influence on the control loop was eliminated by a feedforward compensation strategy. An adaptive phase-locked loop dynamic parameter adjustment model was designed. Proportional coefficients and phase compensation parameters were adjusted. A high-precision rotor position observation model was constructed. Experimental results show that the proposed control strategy achieves comprehensive improvements in speed tracking response, dynamic stability, and steady-state accuracy through coordinated optimization of multiple modules, while ensuring high precision and strong disturbance rejection capability in rotor position estimation, thereby effectively addressing the issues of speed fluctuation and position estimation in motor drive systems under external disturbances.