Abstract:When the traditional single motor driven electric tractors were plowing and rotary tillage, the driving motor was often in the low efficiency area. The power of the motor cannot be fully utilized, which leads to the reduction of working time of tractor. Compared with the single-motor driving system, the dual-motor driving system has some advantages, including the operating point of the two motors can be adjusted to optimize the efficiency of the driving system. It can reduce the torque capacity of the single motor, improve the power density of the driving system, and increase the energy efficiency of the tractor under different operating conditions. Firstly, the structure and working principle of the dual-motor coupling driving system for electric tractors were proposed, including single-motor mode and dual-motor mode. According to the proposed structure, combined with the transmission characteristics of the planetary gear mechanism, the driving mode of the dual motors coupled driving system was analyzed and calculated. Secondly, the mathematical model of powertrain for electric tractor was established. On this basis, the simulation test model for electric tractor was built. The coordinated control strategy of the dual motors driving system was designed, and the power distribution rules of the two motors were obtained by simulation test, the simulation results showed that the power distribution ratio of two motors was between 1.31 and 2.62. Finally, a transmission test platform was built and tested under constant load and traction performance was done. The result demonstrated that under the two load conditions, the power distribution ratio of two motors was ranged from 1.07 to 2.73. In constant load test, the system efficiency was the highest when the power distribution ratio was 1.88. When the power distribution ratio was 1.85, the system efficiency was the highest in traction performance test. The dual motors driving system could realize the power distribution of the two motors according to the power distribution rules, which met the working load and reduced the power loss at the same time. Therefore, selecting the corresponding driving modes according to the different working conditions can improve the efficiency of the driving system.
