| Brushless DC motors(BLDCM) are widely used in many fields, such as automation, digital electronics, industrial control, automobile and medical equipment, due to their large torque output, high efficiency, fast response speed, life and high reliability. But the BLDCM driven by square wave has some torque ripple problem. For a high precision system, the torque ripple is an important indicator to measure the performance of the brushless DC motor. In recent years, adjusting the DC bus voltage of during commutation via increasing the pre-stage DC converter becomes one of the control methods to suppress the commutation torque ripple.This paper expounds several reasons for the commutation torque ripple of BLDCM and analyzes the situation of phase current during commutation. The effect of increasing the pre-stage DC converter to suppress commutation torque ripple is verified and the parameters functions of the boost voltage and time which are needed for commutation torque ripple suppression are established. Simply introduces the principle and characteristic of quasi-Z-source, and proposes the design reference on the parameters of electronic components.Then, simulation model of commutation torque ripple suppression was established in the MATLAB/Simulink and the obtained experimental data was analyzed. The simulation results show that the circuit can suppress the commutation torque ripple dynamically. Torque ripple can be reduced to below 8% of the average torque with improving the average output torque properly.Finally, a BLDCM controller based on the STM32 has been set up. Hardware circuit including design and parameters calculation of the controller and the control algorithm of commutation torque ripple suppression are introduced in detail. The pictures of phase current waveform in different speed were analyzed and the results show that the method of commutation torque ripple suppression for brushless DC motor is reliable and efficient. |
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