电动拖拉机双电机耦合驱动系统传动特性研究

Transmission Characteristics of Dual-motor Coupling System for Electric Tractors

针对单电机驱动型式的电动拖拉机难以满足农田作业多工况的问题,提出了一种基于行星齿轮耦合的双电机驱动系统。根据电动拖拉机动力传动系统的结构方案,按多种作业类型对双电机耦合驱动系统的驱动模式进行分析。采用试验数据模型和理论模型相结合的方法,建立电动拖拉机驱动系统关键部件效率模型和整机纵向动力学模型,在此基础上搭建了电动拖拉机控制仿真试验模型。针对不同驱动模式设计了驱动系统综合控制策略,通过仿真试验得到两电机的功率分配规则。在搭建的传动性能试验平台上对双电机耦合驱动系统进行恒定负载试验和牵引性能试验。试验结果表明,两种试验条件下,主、副电机的功率分配比变化范围为1.07~2.73,恒定负载试验中,功率分配比为1.88时系统效率最高,牵引性能试验时,功率分配比为1.86时系统效率最高。双电机驱动系统能够跟随负载变化按照功率分配规则实现两电机的功率分配,满足作业负载的同时降低了功率损耗。

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 between1. 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.