| As the application of brushless DC motor(BLDC)becomes extensive,the demand for control accuracy of high-power BLDC driver system is getting increasing high.In many occasions,the traditional control methods come into troble to satisfy higher control needs than before.For this,this thesis studies the problems of torque ripple suppression,commutation point detection and heavy load starting,the main contents are as follows:Aiming at the torque ripple problem caused by the mismatch of current rate during commutation,a torque pulsation suppression strategy based on Model Predictive Control(MPC)is proposed.Based on the structure and principle of BLDC,combined with the basic principles and characteristics of MPC,a controller is established.The current during the commutation phase is controlled so that the current change rate of the open phase and the turn-off phase is equal,and the non-commutated phase keeps the current constant,thereby suppressing the torque ripple.The control strategy is verified by building a simulation model.The simulation results show that the MPCbased algorithm can effectively suppress the torque ripple.Aiming at the problems of commutation delay and error in the traditional backElectromotive Force(BEMF)zero-crossing detection method,a terminal-voltagebased commutation point detection method is proposed.Study the model and variation law of the terminal voltage,calculate the time of the terminal voltage distortion caused by the shutdown of the continuous flow,set the detection delay time,calculate the terminal voltage threshold of the commutation point according to the change law of the BEMF,the detection terminal voltage and the commutation threshold comparing the commutation point;according to the variation of the stator inductance with the rotor position,three sets of voltage vectors are applied when the motor is stationary,and the initial position of the rotor is detected according to the change trend of the nonconducting phase terminal voltage.The position sensor control method is divided into three parts: rotor initial position detection,commutation point detection,and switching closed-loop control.The experiment is verified by the experimental device,and the motor can run smoothly under different loads.The experimental test platform was built,and TMS320F28035 was used as the main control chip of the control system.The hardware structure and software flow of the control system were designed.The BLDC control system suitable for high-power occasions was developed and tested by the motor type test device.The comparative analysis of the operating data of the control system shows that the controller designed in this thesis has higher efficiency. |
