Research On Brushless DC Motor Drive System For Transplanter

With the development of times,science and technology change rapidly,automatic and intelligent production has been widely used in industrial and agricultural fields,Vegetable&Fruit and flowers and other crops planting equipment are upgrading.China is a large agricultural country,the cultivated area is vast,crop planting is one of the key links of the production process,the traditional manual transplanting is labor intensive,inefficient and costly,so the development of transplanting machine that is suitable for the situation of our country has an important significance for the development of agricultural economy.The core components of the transplanter machine is transplanting,its main role is to make holes and planting,plant the seedlings of machine or artificial seedlings in soil.The design of drive system for transplanter is one of the key techniques of transplanting machine.In order to improve the planting quality of the dibble type planting device(dibble planting apparatus of crank rocker parallelogram mechanism),this paper proposed a design for transplanter based on brushless DC motor drive system to meet the demands of the motion characteristic of planting.On the basis of anglicizing the hanging cup transplanter hanging cup structure and the law of motion in vertical direction,the paper extracts the operation requirements for transplanter and key parameters for driving system.Drive system design goal is clear:by adjusting drive motor speed and torque boost transplanter working efficiency,thus increasing the hanging cup trajectory of the lowest point of the acceleration,and ultimately improve the penetration ability of the hanging cup,make the seedlings reach the desired depth.Then design brushless DC motor drive system for transplater,mainly including five aspects:(1)analysis the working principle and mathematical model of the brushless DC motor,set up the mathematical model of Brushless DC motor,finally decide to use the pulse width modulation(PWM)control strategy for speed control,adopt the speed and current double closed loop control structure and realize drive system speed adjustment.At the same time,according to the planting operation requirements and the key parameter of the driven system to select motor and reducer for the system.(2)the drive system choose TMS320F28335 DSP as controller chip,timer part of the chip,PWM capture and sample part,ADC sample part are designed,through software to detect the rotor position,the rotating magnetic field signal output,PWM to adjust the speed of motor and PI closed loop control.(3)Analyses the structure and working principle of the drive and design signal processing module for the corresponding signal transmission between the driver,controller and motor transmission,including the PWM processing module,Holzer signal processing module,current detection module etc.(4)Combined with the design requirements of the drive system and related control theory,complete the software design of the drive system in the CCS3.3,software function include system initialization,interrupt,timer interrupt,PWM capture the motor start and stop,ADC sampling interrupt and PI closed loop design.We conduct relevant test and debug on the planting driver system's hardware and software and verified its reliability and stability of software and hardware design,then run on the building experimental platform,the acceleration changes with accelerometer measured hanging Cup campaign consistent with the expected trajectory;and conducted punching experiments,measuring the penetration depth to confirm that the designed drive system is able to improve the point hitting acceleration of the transplanter.That validates the reliability of the designed drive design.