Research On Sinusoidal Control Of Permanent Magnet BLDC Motor For Electric Vehicle

Permanent magnet brushless DC motor has high efficiency, small volume, light weight,high starting torque, simple structure, reliable operation, high speed performance and so on. Itcan satisfy frequent starting/braking, energy-feedback and efficiency requirements of electriccar, many of the micro-electric car currently on the market use the motor as a driving motor.But BLDC has a relatively large torque ripple, it causes the drive noise is relatively large, soBLDC application is very limited in passenger cars. The sine wave control forpermanent-magnet brushless DC motor is studied in this paper and the traditionaldisadvantages of large torque ripple of brushless DC motor can be improved to a great extent.The sinusoidal magnetic field permanent magnet brushless DC motor is the object of thispaper. The BLDC’s stator and rotor structure are similar with the one of permanent magnetsynchronous motor, the mathematical model of permanent magnet brushless DC motor isestablished based on surface mounted permanent magnet synchronous motor in this paper.Based on the mathematical model, the vector control system is designed which sets thethree-phase stator current as control objectives and the voltage space vector inverter controlsystem which sets the stator flux as control objectives. After comparing the advantages anddisadvantages of two control methods, and finally established the voltage space vectorinverter control system which sets the stator flux as control objectives as permanent magnetbrushless DC motor control strategy. Permanent magnet brushless DC motor uses a Hallsensor, only a finite number of rotor positions can be detected. Sine wave control requiresaccurate rotor position, the paper quotes the model reference adaptive system (MRAS) toestimate the rotor position and uses the position of the Hall sensor output rotor position tocalibrate the estimation results Periodically.In hardware design, the TMS320f28069produced by TI is selected as controller CPU;the three-phase full-bridge inverter structure is designed to achieve the motor four-quadrantoperation; the MOS transistors in parallel structure is designed to achieve high current output;the suspended bootstrap driver circuit is designed for MOS tube; the high-speed optocoupleris designed to isolate strong and weak electrically; the voltage detection, current sensing, Hallsignal detection, temperature detection, CAN bus communication circuit and power supplycircuit are designed.In software design, the system initialization process is designed; the hierarchicalsampling structure to is designed ensure the highest sampling efficiency; the troubleshootingmethods is designed to ensure that the system can be protected with the fastest speed innecessary time; the gear conversion process is designed to ensure every time shift is write andsafe; the SVPWM program structure is designed to ensure every time calculated PWM drivesignal is accurate and reliable; the CAN bus send structure is designed to maximize the use ofCAN bus. Through experiments, collecting the motor phase current and torque ripple of the squarewave and sine wave control, the effects of the two control modes are compared, results showthat sinusoidal permanent magnet brushless DC motor control can improve torque ripplegreatly.