Research And Design Of BLDCM Four Quadrant Operation Control System

Energy conservation and efficiency are the main themes of industrial economic development.Motors are the main source of power in all walks of life.BLDCM stands out because of its simple control method,high efficiency and high power density.In industrial fields with high automation,motors frequently operate in four quadrants.Traditional motor control systems often use diode rectification,and energy cannot flow in both directions.Therefore,the four-quadrant operation of the motor often uses energy-consuming braking and reverse braking.By replacing the traditional diode rectifier with a voltage type PWM rectifier,the BLDCM four-quadrant operation control system is formed to improve the network side current and solve the problem of BLDCM four-quadrant operation,which is of high research value.In this paper,the working principle of BLDCM four-quadrant operation control system is analyzed firstly.The principle of BLDCM regenerative braking and the state of winding current in regenerative braking are also deduced.The mathematical models of BLDCM and voltage type PWM rectifier are established to provide a theoretical basis for the formulation of control strategy.This thesis starts with the control strategy of BLDCM four-quadrant operation control system.Through the analysis of the response speed and difficulty of the control system,the controllable rectification of the PWM rectifier is realized by direct power control.By comparing and analyzing different sampling modes,the sampling mode applicable to the system is selected.The dynamic process of converting BLDCM from electric state to feedback braking state is deduced.The modulation method combining PWM_OFF and OFF_PWM is proposed for the defects of existing feedback mode,and the specific feedback process under this modulation mode is analyzed in detail.The cause of the torque ripple during the feedback braking process is deduced in detail,and it is suppressed by the overlap commutation method.The compensation time is determined by detecting whether the phase current is zero or not,and the phase power tube is turned on during the compensation time.So that the two phase current slopes are uniform to suppress torque ripple.The constant torque feedback and variable torque feedback strategy are selected according to different loads.On this basis,the overall control strategy of BLDCM four-quadrant operation control system is established.The simulation model of the theory and control strategy proposed in this paper is validated,and the hardware and software analysis of the control system designed in this paper is carried out.The BLDCM four-quadrant operation control system with DSP&CPLD as the core is built to realize the four-quadrant operation of BLDCM.Through the detailed analysis of the experimental results,the correctness and feasibility of the theory and control strategy proposed in this paper are verified.