Design And Test Of Loading Platform For A Series Of Diesel Electric Hybrid Tractor

Under the condition of short energy,polluted environment and abnormal climate,the research of environment friendly tractor is of significant importance to reduce environmental damage and achieve sustainable energy development for China which is a traditional agricultural country.Electric tractors and hybrid tractors as the most outstanding type among environment friendly tractors are the trend of development of future tractors.While electric tractor limited by its battery technology is hard to achieve a breakthrough in short time,hybrid tractor is the best choice which not only be able to meet the requirement of agricultural development,but also to save energy and protect environment.A design of multifunctional loading platform for series hybrid tractors was proposed in the paper since it is difficult and unpredictable to establish a simulation test model in computer and the building period of test platform for real car is too long and the cost is huge.Aimed at achieving its all functions,the overall scheme for the platform was divided into six parts of driver operation module,engine testing module,power supply module,hub motor control module,analog loading module and data acquisition module,based on which the detailed structure was designed and built.The tests of loading module-loading platform were conducted particularly.The acquisition and control module was designed that an engine was used as its power supply;with battery pack,a motor drove by generator and controller was used to simulate different working conditions;and collected data were sent back to host computer by data acquisition devices.After calibrating the major equipment(torque speed sensor,current voltage sensor,magnetic powder brake,etc.)and conducting preliminary test for wheel motor load characteristics,the tests of three typical working conditions of tractor(Road transport,ploughing and sudden loading)were conducted.The results are as follows:(1)The output characteristic curve of the hub motor is approximately hyperbolic.Its velocity decreased with the increase of its torque,while its output power decreased and its efficiency increased with the increase of its velocity.The hub motor could be drove along,and it had relative large velocity range and overload capacity,as well as the characteristic of decreasing velocity while increasing torque,which can meet the requirements for tractor of working in field.(2)The driving torque was constant when working in a constant speeding for road transport,while the torque increased or decreased in order to overcome inertia force when accelerating or decelerating.The driving torque when working in a constant speeding for ploughing differed a lot according to different field conditions and was larger than the torque mentioned first,which means the torque of each component in tractor increased with the increase of load.(3)The output responding accuracy of loading module employing PID algorithm was improved significantly compared to the one without the algorithm,so does the responding time.The research in the paper can provide a basic theory and technology support for the later design of driving and control system of hybrid tractor,and provide an important reference for real tractor test.