Hybrid converter topology for reducing torque ripple of BLDC motor


 This study investigates the torque ripple performance of brushless DC (BLDC) motor drive system by integrating both modified single-ended primary inductor converter (SEPIC) and silicon carbide metal–oxide–semiconductor field-effect transistor based three-level neutral-point-clamped (NPC) inverter. In BLDC motor, the high commutation torque ripple is an important origin of vibration, speed ripple and prevents the use of the BLDC motor drive system in high-performance and high-precision applications. For torque ripple reduction, the modified SEPIC converter is employed at the entrance of the three-level NPC inverter, which regulates the DC-link voltage according to the motor speed. Moreover, the three-level NPC inverter is employed as a second-stage converter to suppress current ripple for further torque ripple reduction. Finally, the performance of the proposed hybrid converter topology is verified by simulation and laboratory experimental results.


  1. DSP controller
  2. Energy eficiency
  3. Fuzzy logic (FL)
  4. MPPT
  5. Photovoltaic systems



A novel hybrid circuit topology has been proposed in this paper which is built by a modified SEPIC converter and a SiC-MOSFETbased three-level NPC converter for minimising torque ripple in a BLDC motor drive system. For efficient reduction of torque ripple, the first stage is the modified SEPIC converter that lifts the DClink voltage to the desired value based on the motor speed measurement. For further torque ripple reduction, the three-level NPC inverter is employed as the second-stage converter to suppress current ripple. Experimental results show that the proposed hybrid converter topology can suppress the torque ripple to 14.6% at the speed of 6000 rpm, commutation torque ripple is reduced substantially and produce smooth torque waveform than the BLDC motor driven by the two-level, three-level NPC, twolevel inverter with DC-link voltage control, and two-level inverter with SEPIC converter and switch selection circuit topologies.


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[3] Lee, S.K., Kang, G.H., Hur, J., et al.: ‘Stator and rotor shape designs of interior permanent magnet type brushless DC motor for reducing torque fluctuation’, IEEE Trans. Magn., 2012, 48, pp. 4662–4665

[4] Seo, U.J., Chun, Y.D., Choi, J.H., et al.: ‘A technique of torque ripple reduction in interior permanent magnet synchronous motor’, IEEE Trans. Magn., 2011, 47, (10), pp. 3240–3243

[5] Murai, Y., Kawase, K., Ohashi, K., et al.: ‘Torque ripple improvement for brushless DC miniature motors’, IEEE Trans. Ind. Appl., 1989, 25, (3), pp. 441–450

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