| With the rapid development of agricultural modernization,agricultural machinery vehicles are playing a more and more important role.At present,there are two kinds of hybrid and pure electric power in the research of the power transmission structure of agricultural machinery vehicles,however,the hybrid structure is still difficult to avoid the pollution caused by fuel oil.With the development of vehicle dynamics electrification,pure electric power transmission has become a hot research topic in vehicle power transmission.At present,the pure electric power transmission is mainly driven by single motor and multiple speed ratio,double motor drive and wheel motor drive,because of the working environment and working characteristics,the structure above are mainly used for electric vehicles and construction machinery,difficult to apply to agricultural machinery vehicles.In this paper,according to the working environment characteristics of pure electric power transmission and the research status of pure electric power transmission,a test bench which was suitable for agricultural machinery vehicles and contained double motor parallel coupled input single output transmission structure was designed,this transmission structure could not only increase the speed range,enhanced the coupling power,could also solve the problem in that the single small power single motor damaged due to lack of power,small speed range and a single large power motor had a large load,energy loss and other issues,it could meet the demand of the vehicle in complex environment as well,The experimental research platform was provided for the follow-up study of dynamic optimization and optimal power balance matching of dual motor power coupled agricultural machinery vehicle.The main work of the design of the test bench is summarized as follows:1.Operation principle analysis and mathematical model establishment of brushless DC motor.In order to realize the stepless speed regulation of dual-motor,the structure and operation principle of the brushless DC motor were analyzed,the mathematical model of the motor was established,according to the principle and method of stepless speed regulation,the control mode,control structure and control strategy of the stepless speed regulation of the motor controller were analyzed.2.Design and operation analysis of gear box transmission structure.With planetary differential gear as the main transmission mechanism,combining the characteristics of power source,the relationship between output speed and torque and input speed and torque of the planetary differential gear transmission and its transmission efficiency were analyzed.According to the transmission characteristics of planetary differential gear,The structure of transmission gear box with double input and single output was designed,combining the design parameters of gear box,based on the operationg analysis of planetary differential gear,the relationship between output and input of the speed and torque of motor independent work and double motor work together during the operation of the test bench were derived.3.Simulation experiment design and result analysis of double motor coupling drive system.The simulation model of the dual motor coupling drive system was established by using the dynamic simulation platform SimulationX,the relationship between the output input speed and torque wa analyzed when the system is working independently by a motor and working together by the double motors.The simulation results showed that when the system was loaded,the speed of the motor became longer.When the motor reached the steady state,the relationship between the output speed and torque and the input speed and torque were consistent with the theoretical calculation.Ignore the influence of gear meshing friction,the coupling output of double motor speed range increased 29.17%,to achieve the goal of increasing the speed range.4.Design and implementation of hardware system and software measurement and control system of the test bench.Design content mainly included five parts:(1)Drive control system,double closed loop control structure with PWM control mode and hardware PI regulator IPM Controller was adopted,realized the stepless speed regulation of the motor.(2)Coupling transmission system,with planetary differential gear as the main structure,designed fixed axis gear as input of double motor,according to the fixed axle gear driving the sun gear and the inner gear ring of the planetary differential gear,which realized the transmission gear box with double input and single output structure.(3)Sensor detection system,using high precision AN series bus digital torque and rotational speed sensor JN338,the controller and the sensor were connected with the bus structure,connected with PC machine through 485 turn 232,realized real-time detection of the speed and torque of the input and output of the test bench.(4)Simulated loading system,using XZ25YS magnetic powder brake,changing the friction force by adjusting the excitation current of the tension regulator,realized the loading function.(5)Communication and software measurement and control system,with VC++ as development platform,the serial data communication between upper and lower computer was realized based on Modbus bus transmission protocol.Through the PC machine can set the speed value of the dual motor,to achieve the motor control.At the same time,the rotational speed and torque value collected by the sensor was transmitted on the PC,realized the real-time display of the detection data and speed curve.And the detected data was stored in the Access database.5.Test bench test and result analysis.Software and hardware system of test bench was assembled,dual motor stepless speed regulation and coupling transmission test bench did the experiment test under the condition of single motor and double motor,the output rotational speed and input speed of the motor under different working modes were analyzed.The test results show that the test bench can run stably,and through comparing the speed output curve with input curve,the dual motor coupling output achieves the goal of increasing speed range.By the experimental error analysis,when dual motor coupling running speed is less than 1400r/min,under no load condition,the average error of the output speed and the theoretical output value is less than 3.5%,under load condition,the average error of the output speed and the theoretical output value is less than 8.5%,therefore,comparing the dual motor coupling work with the motor independent work,the system’s anti-interference ability and stability enhanced. |
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