Commutation torque ripple suppression method for brushless DC motors with minimum phase shift angle

Commutation torque ripple occurs when brushless DC (BLDC) motor runs in the high-speed range, which degrades operation performance. To overcome the problem, this paper presents a commutation torque ripple suppression method based on the minimum phase shift angle (MPSA) of hall signals. In the paper, the effect of the phase shift angle (PSA) of hall signals on phase current is analyzed, and the MPSA is deduced on the basis of the unit duty cycle of the incoming and non-commutation phase. With the proposed method, two-phase conduction mode is used in the full speed range, commutation period and non-commutation period, which avoids switching modulation mode and enhances system reliability. The proposed method is implemented through shifting hall signals by the MPSA, and it is simple and feasible without the requirement to redesign a controller. Moreover, no additional power devices and precise sensors are required, which reduces design cost and volume size. The proposed method is experimentally compared with different methods under steady operation condition, and the results show superior performance on suppressing commutation torque ripple. The loading experiment demonstrates that the proposed method exhibits good dynamic response. The frequency spectrum of the electromagnetic torque is analyzed, and it is verified that the 6nf harmonics are diminished with the proposed method.