Research On Brushless DC Motor Torque Control Technology

The brushless DC motor(BLDCM)is widely used in every field of national economy.Brushless DC motors have a series of advantages such as high power density,good speed control performance,high operating efficiency,and simple control,making them widely used in industrial,aerospace,automotive and other fields.In this paper,torque control as the main research object,a variety of different control methods are proposed for the torque control problem.By introducing the coordinate transformation into the analysis of the commutation process,the voltage balance equation in the two-phase ?? stationary coordinate system is obtained,and the graphical analysis method of the commutation process is obtained by combining the output voltage vector of the inverter and the motor phase current vector.It greatly simplifies the analysis process of the commutation process,avoids complex formula calculation and commutation path analysis,and can intuitively obtain various commutation process control methods.For the commutation torque ripple,a method of reducing the commutation torque ripple by the PWM modulation method is obtained according to the graphical analysis method.As the research progressed,it was found that when the torque ripple suppression method is adopted,the commutation time may be prolonged,and the commutation failure may occur under heavy load or high speed conditions.Based on this,a control method for reducing the commutation time is proposed,which combines the method for reducing the commutation time and the method for reducing the commutation torque ripple to obtain a method for coordinated control of commutation time and commutation torque ripple.By using this method,the minimum commutation torque ripple control effect can be obtained on the premise of a given commutation time.Based on the many advantages of the hysteresis control,applying it to the control of the motor phase current is bound to obtain a good torque control effect.This paper obtains the commutation torque ripple suppression method under the motor state and the braking state through analysis.The commutation logic of the motor;the switching process between the motoring state and the braking state and the fast switching of running state methods are also elaborated in the text.For non-commutation process torque ripple,based on the advantage of DBC being able to quickly track a given current,a new DBC method is proposed to reduce the torque ripple in the non-commutation process.This method allows the actual motor phase current to be tracked in real time.Thus,ensure that the motor output electromagnetic torque is constant and suppress non-commutation torque ripple.Finally,a hardware platform was built to carry out experiments.The experimental results show the correctness and effectiveness of the proposed method.