[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.