Research On The Suppression Method Of DTC Torque Ripple Of Two-phase Conduction Brushless DC Motor

Brushless dc motor(BLDCM)has been widely applied in industry production and social life thanks to the advantages of smaller volume,high power density,replacement of mechanical commutator and higher safety coefficient.Directly aiming at the Electromagnetic Torque,direct torque control(DTC)owned fast torque response and high-performance of dynamic and static operation.At present,direct torque control has achieved great success in permanent magnet synchronous motor,and asynchronous motor control system.When it comes to BLDCM control system,the specific non-sinusoidal back EMF and two-phase conduction mode make BLDCM direct torque control become a hot research issue.The torque ripple reduction methods are mainly discussed in two-phase conduction mode of brushless DC motor DTC system.First of all,a mathematical model of the BLDCM with a detailed analysis of the control principle of DTC and voltage vector selection scheme was established.Then,two phase conduction mode BLDCM DTC system is obtained.Matlab/Simulink software is used to build a simulation model of DTC system as a foundation for further study and improvement.An experiment platform of BLDCM based on DSP TMS320F28335 is introduced.All the results of the hardware experiments are realized using this platform.Secondly,the factors that cause the greater torque ripple are analyzed by the analysis of the two-phase conduction mode BLDCM DTC mathematical model with mathematical deduction.Then,an improved DTC control method for brushless DC motor based on duty cycle modulation is proposed.The results of simulation and experiment verify the effectiveness of theanalysis proposed method for suppressing torque ripple.Based on the study above,further is carried out aiming at different commutation process by mathematical model.By comparing phase current ripple using different zero voltage vectors,a suitable voltage vector selection method is obtained in order for smaller commutation torque ripple.The simulation results in agreement with the experimental results preliminarily show that the proposed method has the advantage of avoiding commutation torque ripple.