Development And Experiment Of Greenhouse Dual Power Electric Tractor

Based on the NWSUAF’S previous development of the greenhouse electric tractor, this study developed a greenhouse dual power mini-electric tractor(hereinafter referred to as "dual power electric tractor") and tested its relevant performance, which aimed at the major drawback of the prototype’s short life and inconvenience operation of the speed change. The main contents of this study include the following four aspects:1. Determination of the main program. By reason analysis for the prototype’s short life, then learning from the transmission structural aspects of electric vehicle and hybrid crawler tractors both in China and abroad, this study designed the overall layout of the dual power electric tractor and also built a 3D model for it. On this basis, we chose a scheme with the combination of DC motor and AC motor, which will realize the power transmission through the mechanical transmission; we also designed a scheme of electric drive system which is suitable for the dual power electric tractors according to the characteristics of the power supply scheme and mechanical transmission.2. Main components’ design and manufacture. According to the operating parameters of the original prototype and the electric drive system of the dual power electric tractor, we designed and manufactured the main components which satisfied the requirements of its operating condition, and finally, we completed the tractors’ assembly.3. Remote transmission’s design and manufacture. We designed and produced the remote transmission by combining with the characteristics of the electric drive system proposed before, then tested the device for the work gear and reverse gear of the prototype. The preliminary test results showed that this device can realize remote control shifting of the dual power electric tractors. In the absence of obstruction interference, the remote control distance was about 35 m. The work gear and reverse gear’s speed range respectively was 0 ~ 0.73m/s and 0 ~ 0.59m/s, this test results showed that the remote transmission could meet the design requirements.4. Related performance tests. We tested the dual power electric tractor according to the GB / T 3871-2006, the rule of agricultural tractor test procedures:(1) Tests of the centroid position. The results showed that the horizontal longitudinal coordinate of the tractors’ centroid position located in 34.2mm before the track’s on ground length center, which met the requirements of the centroid position when the crawler tractors have towing operations. The centroid coordinates of the horizontal lateral which was-9.8mm showed the main components of the prototype were almost arranged symmetrically. It’s also conducive to improve the longitudinal stability of the prototype with a 40mm-height below about the vertical coordinate.(2)Tests about the endurance time, the steering operational performance(including steering maneuverability & driving linearity), the relationship between tractions and slip rates with different inverter output frequency. The results showed three main parts:A. The prototype can operate in the case of continuous uninterruptible power, which significantly improved the original prototypes’ main drawback.B. The minimum of the tractors’ turning radius is 1148 mm, and the proto tractors’ geometrical parameters satisfied the steering mobility requirements when the crawler tractors drived with no-load, which indicated that the proto tractors had a better steering mobility and this kind of tractors can suite the relatively narrow operating condition in greenhouse.C. The 0.54% crabbing rate under no-load driving condition also indicated that it had a better driving linearity with no-load.D. Under a constant inverter output frequency, the tractors’ slip rate increased with the traction. Under the same traction, the corresponding slip rate fell as the frequency rose.