Optimize Driving System Of Direct Current Motor For Drive System Design And Fault Analysis

In recent years,many research and applications of the multi rotor unmanned aerial vehicle(UAV)are expanding gradually and most of the multi rotor uav is using sensor less brush less DC motor as a power base.As the outer rotor structure,the non-inductive brush less DC motor drives the propeller to rotate at high speed.Brush less DC motor is mainly divided into two kinds,one is with hall position sensor control,the other is no hall position sensor control.The structure of brush less DC motor with Hall sensor control is relatively complex and the reliability is poor.Compared with the DC motor controlled by Hall sensor,the DC motor controlled by a no position sensor is suitable for a wide range of application,and it has a high reliability and great advantages.Therefore,now use the sensor less control.The sensor less control of brush less DC motor(BLDCM),not directly to detect the rotor position sensor,but in the process of motor function,still need the rotor position signal to control the motor commutation.Therefore,how to obtain precise rotor position signal and control motor commutation becomes the key of brush less DC motor control without position sensor.At present,the methods of obtaining the rotor mainly include the back EMF third harmonic integral detection method,flux estimation method,freewheeling diode detection method,extended Kalman filter method,back-EMF zero-crossing detection method,etc.Because the DSP has a powerful computing power,if we use DSP as a DC motor control chip,the motor can quickly and accurately start and control,but its cost ishigh,the circuit structure is relatively complex,and there is low-speed position detection error.Based on the back-EMF zero-crossing detection circuit,six N-type MOSFET are used as the switching devices,and the control modules are selected with high reliability,high integration and control.Function,low-voltage low-power single-chip C8051F500 to achieve,so the external circuit is simple,fast response,high reliability.And take the combination of hardware and software to start and PWM speed control mode to achieve the start and stable operation of the motor to achieve multi-rotor UAV brush less DC motor speed control and control functions.Based on the successful establishment of the drive system,the fault type of the actuator is analyzed,and the real-time status of the motor and the driving board is monitored on-line for the fault of the drive board and the DC motor.This paper will focus on the mathematical model of the position sensor less and brush less DC motor,the rotor position detection of the back EMF method,the hardware design and software design of the drive system,and the common faults of the drive circuit board.Finally,the paper summarizes the work done in this paper,and puts forward the problems that need to be studied in the future.