Development Of A Brushless DC Motor Drive Control Unit For Electric Gear-Type Urea Supply Pumps

This paper mainly aims to develop a brushless DC motor drive control unit of the electric gear pump used for a urea aqueous solution supply system in SCR(selective catalytic reduction)device applying to NO_xaftertreatment systems of the diesel engines which meet the requirements of the China stage VI and beyond emission standards.The main research work is as follows:(1)According to the emission standards of China stage VI and later diesel engines,the application characteristics,control requirements and difficulties of urea aqueous solution,gear-type pump and the airless assisted SCR systems are discussed,the drive and control mode for the electric gear-type urea supply pump are analyzed,and then the drive method and control strategy for the BLDC motor used for a gear-type urea supply pump are proposed.(2)A new fuzzy PID control strategy combining conventional PID and fuzzy control is proposed,and the simulation results show that;after adding the fuzzy PID controller to the DC motor drive control model by MATLAB/SIMULINK,the simulation shows that the motor speed is more stable and response time is less than 2 ms,the overshoot is less than 5%,and the torque ripple is effectively suppressed under fuzzy PID control.(3)The S32K142 chip was selected as the main control chip of the system,and the hardware circuit of the electronic control unit(ECU)of the system was designed based on the Altium Designer software,including the core control circuit,power supply circuit,power drive circuit,back EMF detection circuit and communication circuit,etc.,and then the PCB board was produced.The system control software was written by 32 Design Studio for ARM software,including the main program,fuzzy PID control program and motor forward and reverse rotation program.(4)The experimental platform of gear-type urea supply pump was built,and the experimental results show that the motor speed control error was less than 0.3%,the gear pump work well at a given speed,the system urea solution supply pressure and flow is stable,the design requirements can be satisfied,and then the feasibility and good control performance of the control unit are verified.