电动拖拉机田间巡航作业驱动转矩管理模型
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摘要
针对电动拖拉机整机控制中与驱动转矩相关且通用性较强的功能环节,在驱动系统上层搭建了一种通用型的驱动转矩管理控制模型。以满足田间作业需求、提升作业质量为目标,将输入信号标定为期望作业车速,并进一步转化为电机目标转速。根据实际转速与目标转速的偏差,计算电机目标输出转矩,以使电机需求功率与作业负载相平衡。进一步考虑巡航作业过程中驱动转矩变化引起的整机冲击度、当前转速下电机可用最大转矩以及驱动系统过温、电池放电欠压的影响,依次搭建了针对目标输出转矩的斜坡限制、基于转速的转矩容量限制和极端工况下的比例减载限制模型。搭建了包括电池、驱动电机以及整机纵向动力学在内的电动拖拉机模型。基于驱动转矩管理模型设计了目标控制器,并搭建了dSPACE硬件在环测试平台,分别对转矩管理模型中的各个参数进行了标定,并对牵引作业工况下驱动系统的输出特性进行了测试,结果表明:在牵引作业时,实际车速可平稳跟踪期望作业车速,跟踪误差主要取决于驱动轮的滑转程度,当期望车速改变时,实际车速按标定斜率向期望值平缓过渡;作业过程中,模型输出转矩始终处于电机转矩容量范围以内,且转矩变化率不超过35N·m/s,与未经斜坡限制处理的原始目标转矩相比,转矩变化趋于缓和;当电池输出电压低于欠压报警阈值时,驱动转矩管理模型根据电池欠压程度将模型输出转矩比例缩减10%～27%,确保电池输出电压不低于停机阈值。所搭建的驱动转矩管理模型可为电动拖拉机整机控制器的设计提供技术参考。
Researchers have developed various design methods for driving systems and control strategies for electric tractors, as well as performance analysis of key components. However, little attention has been paid to the precise management of torque requests in the top layer in consideration of factors such as the power output restrictions at motor operating temperature limits, battery state-of-charge limits, time-based torque ramp limits, and the speed-dependent torque capability of the motor. In this paper, we developed a driving torque management model on the upper layer of driving systems for electric tractors based on the common functional blocks related to the decision of target torque in electric tractor control. In order to meet the field operation requirements and improve the quality of work, the input signals were calibrated to the desired cruise speed and further converted to the motor target revolving speed. According to the deviation between the actual revolving speed and the target revolving speed, the motor target output torque was calculated to balance the required motor power with the work load. Further considering the impacts on the electric tractor caused by the torque fluctuations during the cruise operation, the motor maximum torque available at the current revolving speed, the influence of the over-temperature of the driving system and the over-discharge of the battery, models of time-based ramp limitation of target torque, motor's speed-based maximum torque limitation and load reduction protection under extreme conditions were constructed in turn. The electric tractor model consisting of tractor dynamic model, battery model, and electric motor model was also built. A tractor control unit to support the torque demand management model was designed, and a hardware-in-the-loop real-time test platform was built with dSPACE. The parameters in the torque management model were calibrated separately, and the output characteristics of the drive system under traction conditions were tested. The results showed that the actual vehicle speed tracked the expected cruising speed steadily during the traction operation. The tracking error mainly depended on the degree of slip of the driving wheels. When the expected speed changed, the actual vehicle speed smoothly transited to the expected value according to the calibrated climbing rate. During the operation, the model output torque always stayed within the motor torque capacity, and kept a small change rate of not more than 35 N·m/s, which led to more gentle variations of motor torque compared with the original without ramp limitations. When the battery voltage dropped below the over-discharge threshold, the management model scaled down the target torque in time by 10%-27% according to the degree of undervoltage, which therefore kept the battery voltage always above the safe level. The driving torque demand management model built in this paper can provide a technical reference for tractor control unit designs of electric tractors.
Researchers have developed various design methods for driving systems and control strategies for electric tractors, as well as performance analysis of key components. However, little attention has been paid to the precise management of torque requests in the top layer in consideration of factors such as the power output restrictions at motor operating temperature limits, battery state-of-charge limits, time-based torque ramp limits, and the speed-dependent torque capability of the motor. In this paper, we developed a driving torque management model on the upper layer of driving systems for electric tractors based on the common functional blocks related to the decision of target torque in electric tractor control. In order to meet the field operation requirements and improve the quality of work, the input signals were calibrated to the desired cruise speed and further converted to the motor target revolving speed. According to the deviation between the actual revolving speed and the target revolving speed, the motor target output torque was calculated to balance the required motor power with the work load. Further considering the impacts on the electric tractor caused by the torque fluctuations during the cruise operation, the motor maximum torque available at the current revolving speed, the influence of the over-temperature of the driving system and the over-discharge of the battery, models of time-based ramp limitation of target torque, motor's speed-based maximum torque limitation and load reduction protection under extreme conditions were constructed in turn. The electric tractor model consisting of tractor dynamic model, battery model, and electric motor model was also built. A tractor control unit to support the torque demand management model was designed, and a hardware-in-the-loop real-time test platform was built with dSPACE. The parameters in the torque management model were calibrated separately, and the output characteristics of the drive system under traction conditions were tested. The results showed that the actual vehicle speed tracked the expected cruising speed steadily during the traction operation. The tracking error mainly depended on the degree of slip of the driving wheels. When the expected speed changed, the actual vehicle speed smoothly transited to the expected value according to the calibrated climbing rate. During the operation, the model output torque always stayed within the motor torque capacity, and kept a small change rate of not more than 35 N·m/s, which led to more gentle variations of motor torque compared with the original without ramp limitations. When the battery voltage dropped below the over-discharge threshold, the management model scaled down the target torque in time by 10%-27% according to the degree of undervoltage, which therefore kept the battery voltage always above the safe level. The driving torque demand management model built in this paper can provide a technical reference for tractor control unit designs of electric tractors.
引文
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[23]杨竞喆,王志福,刘杰.基于MC9S12XEP100的整车控制器CAN BootLoader设计与实现[J].车辆与动力技术,2014(1):25-29.Yang Jingzhe,Wang Zhifu,Liu Jie.Design and implementation of can bootloader for vehicle control unit based on MC9S12XEP100[J].Vehicle&Power Technology,2014(1):25-29.(in Chinese with English abstract)
[24]蔡敏超,殷浩,舒少龙.基于Simulink/Stateflow的纯电动汽车整车上下电策略[J].系统仿真技术,2018,14(1):30-38.Cai Minchao,Yin Hao,Shu Shaolong.Power up down strategy of pure electric vehicles based on simulink/stateflow[J].System Simulation Technology,2018,14(1):30-38.(in Chinese with English abstract)
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[2]Moreda G P,Mu?oz-García M A,Barreiro P.High voltage electrification of tractor and agricultural machinery-a review[J].Energy Conversion and Management,2016,115:117-131.
[3]方树平,王宁宁,易克传,等.纯电动拖拉机动力系统设计及性能分析[J].中国农机化学报,2017,38(1):80-84.Fang Shuping,Wang Ningning,Yi Kechuan,et al.Design and performance[J].Journal of Chinese Agricultural Mechanization,2017,38(1):80-84.(in Chinese with English abstract)
[4]张铁民,闫国琦,温利利,等.我国电动力农业机械发展现状与趋势[J].农机化研究,2012,34(4):236-240.Zhang Tiemin,Yan Guoqi,Wen Lili,et al.Current situation and development of electric agricultural machinery in China[J].Journal of Agricultural Mechanization Research,2012,31(4):236-240.(in Chinese with English abstract)
[5]Lombardi G V,Berni R.Choice modelling and forecasting demand for alternative-fuel tractors[J].Advances in Data Mining:Applications and Theoretical Aspects,2014,8557:115-129.
[6]Yuko U,Jun Y,Kazunobu S,et al.Study on the development of the electric tractor-specifications and traveling and tilling performance of a prototype electric tractor[J].Engineering in Agriculture,Environment and Food,2013,6(4):160-164.
[7]Weerachai A,Masayuki K,Tomohiro T,et al.Preliminary study on the applicability of an electric tractor(Part 1)-energy consumption and drawbar pull performance[J].Journal of JSAM,2001,63(3):130-137.
[8]Weerachai A,Masayuki K,Tomohiro T,et al.Preliminary Study on the applicability of an electric tractor(Part 2)-effect of battery allocation on the tractive performance[J].Journal of JSAM,2001,63(5):92-99.
[9]Hossein M,Alireza K,Arzhang J.Evaluation of alternative battery technologies for a solar assist plug-in hybrid electric tractor[J].Transportation Research,2010,15(8):507-512.
[10]方树平,王宁宁,徐立友,等.纯电动拖拉机与传统燃油拖拉机性能对比分析[J].农机化研究,2018,40(2):241-246.Fang Shuping,Wang Ningning,Xu Liyou,et al.Performance comparison between pure electric tractor and conventional fuel tractor[J].Journal of Agricultural Mechanization Research,2018,40(2):241-246.(in Chinese with English abstract)
[11]陈黎卿,詹庆峰,王韦韦,等.纯电动拖拉机电驱动系统设计与试验[J].农业机械学报,2018,49(8):388-394.Chen Liqing,Zhan Qingfeng,Wang Weiwei,et al.Design and experiment of electric drive system for pure electric tractor[J].Transactions of the Chinese Society for Agricultural Machinery,2018,49(8):388-394.(in Chinese with English abstract)
[12]邓晓亭,朱思洪,高辉松,等.混合动力拖拉机传动系统设计理论与方法[J].农业机械学报,2012,43(8):24-31.Deng Xiaoting,Zhu Sihong,Gao Huisong,et al.Design theory and method for drive train of hybrid electric tractor[J].Transactions of the Chinese Society for Agricultural Machinery,2012,43(8):24-31.(in Chinese with English abstract)
[13]徐立友,刘孟楠,周志立.串联式混合动力拖拉机驱动系设计[J].农业工程学报,2014,30(9):11-18.Xu Liyou,Liu Mengnan,Zhou Zhili.Design of drive system for series hybrid electric tractor[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2014,30(9):11-18.(in Chinese with English abstract)
[14]徐立友,张俊江,刘孟楠.增程式四轮驱动电动拖拉机转矩分配策略[J].河南科技大学学报:自然科学版,2017,38(5):80-85.Xu Liyou,Zhang Junjiang,Liu Mengnan.Torque distribution strategy of extended range electric tractor[J].Journal of Henan University of Science and Technology:Natural Science,2017,38(5):80-85.(in Chinese with English abstract)
[15]Liu Mengnan,Xu Liyou,Zhou Zhili.Design of a load torque based control strategy for improving electric tractor motor energy conversion efficiency[J].Mathematical Problems in Engineering,2016,2016:1-14.
[16]武仲斌,谢斌,迟瑞娟,等.基于滑转率的双电机双轴驱动车辆转矩协调分配[J].农业工程学报,2018,34(15):66-76.Wu Zhongbin,Xie Bin,Chi Ruijuan,et al.Active modulation of torque distribution for dual-motor front-and rear-axle drive type electric vehicle based on slip ratio[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(15):66-76.(in Chinese with English abstract)
[17]谢斌,张超,陈硕,等.双轮驱动电动拖拉机传动性能研究[J].农业机械学报,2015,46(6):8-13.Xie Bin,Zhang Chao,Chen Shuo,et al.Transmission performance of two-wheel drive electric tractor[J].Transactions of the Chinese Society for Agricultural Machinery,2015,46(6):8-13.(in Chinese with English abstract)
[18]谢斌,张超,毛恩荣,等.基于my RIO的电动拖拉机驱动控制器设计与室内试验[J].农业工程学报,2015,31(18):55-62.Xie Bin,Zhang Chao,Mao Enrong,et al.Motor controller design and indoor experiment for electric tractor based on myRIO[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2015,31(18):55-62.(in Chinese with English abstract)
[19]高辉松,朱思洪.电动拖拉机传动系设计理论与方法研究[J].南京农业大学学报,2009,32(1):140-145.Gao Huisong,Zhu Sihong.Study on design theory and method for driving line of electric tractor[J].Journal of Nanjing Agricultural University,2009,32(1):140-145.(in Chinese with English abstract)
[20]高辉松,王珊珊,朱思洪.电动拖拉机驱动力与传动效率特性试验[J].农业机械学报,2008,39(10):40-43.Gao Huisong,Wang Shanshan,Zhu Sihong.Experiment on characteristics of driving force and transmission efficiency of electric tractor[J].Transactions of the Chinese Society for Agricultural Machinery,2008,39(10):40-43.(in Chinese with English abstract)
[21]商高高,张家俊.电动拖拉机驱动控制策略开发[J].中国农机化学报,2016,37(6):149-153.Shang Gaogao,Zhang Jiajun.Development of electric tractor powertrain control strategy[J].Journal of Chinese Agricultural Mechanization,2016,37(6):149-153.(in Chinese with English abstract)
[22]刘成强,林连华,徐海港.电动车辆整车控制器的研发[J].农业装备与车辆工程,2016,54(8):13-16.Liu Chengqiang,Lin Lianhua,Xu Haigang.Research and development of electric vehicle controller[J].Agricultural Equipment&Vehicle Engineering,2016,54(8):13-16.(in Chinese with English abstract)
[23]杨竞喆,王志福,刘杰.基于MC9S12XEP100的整车控制器CAN BootLoader设计与实现[J].车辆与动力技术,2014(1):25-29.Yang Jingzhe,Wang Zhifu,Liu Jie.Design and implementation of can bootloader for vehicle control unit based on MC9S12XEP100[J].Vehicle&Power Technology,2014(1):25-29.(in Chinese with English abstract)
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