[Objective] The extended kalman filter (EKF) is widely used in sensorless brushless DC motor drive systems and can recursively estimate rotor position and speed based on the nonlinear motor model. However, the inherent linearization characteristic of the EKF results in limited approximation accuracy, making the estimator extremely sensitive to parameter uncertainties, model mismatches, and deviations in noise statistics. These limitations can cause the estimated electrical angle and speed to drift over time, leading to commutation errors and significantly reducing motor operating performance. [Methods] To address this issue, this paper proposed a commutation error correction method based on the phase synchronization between the fundamental components of phase back electromotive force and phase current. Firstly, a variable center frequency fundamental extraction filter was employed to extract the fundamental components of both phase current and phase back electromotive force. Secondly, using the vector relationships in the two-phase coordinate system, a commutation error indicator was constructed. When this commutation error indicator was greater than zero, it indicated lagging commutation, when less than zero, it indicated leading commutation. Finally, the commutation error indicator was closed-loop regulated through a proportional integral controller, driving it toward zero and thereby achieving adaptive correction of the commutation timing. [Results] The simulation and experimental results showed good consistency. The proposed method exhibited strong robustness against phase errors induced by various non-ideal factors within the control loop, effectively correcting commutation errors, significantly improving the symmetry of the current waveforms, rendering the commutation process smoother and more stable. Under both lagging and leading commutation conditions, the peak-to-peak values of phase current were reduced by 75% and 67% respectively, and the rotor position error remained within 0.2 rad. [Conclusion] The proposed commutation error correction method based on EKF and phase synchronization of fundamental components between phase current and phase back electromotive force effectively corrects commutation errors, significantly reduces power loss, and enhances both system efficiency and operational stability.