电动轮驱动汽车动载冲击下空间失稳演化机理与防侧翻控制研究

In-wheel motor drive electric vehicle has the advantages of compact structure, high transmission efficiency and flexible control, however the unsprung dynamic load is too large in the transient steering with driving/braking on uneven roads. In these situations, the wheels might be easily lead to jump and the tyres will lose adhesion, which might be able to make the vehicle occur wandering, rollover and other spatial instability problems. At present, the dynamic mechanism in the above evolution process has not been revealed in theory and the systematic solution for its spatial stability control also has not been proposed in the international. For the purpose of resolving the above problems, the following research will be done in this project: To build a multidimensional nonlinear dynamics model for the development of control strategies, which coveres the models of road, electric wheels, suspensions and vehicle body; To analyse the combined effects of various incentive to road adhesion, which include the wheel-motor torque ripple, the brake pressure pulsation, the suspension space constraints, the tires delay and tolerance characteristics; To reveal the spatial instability evolution mechanism of the vehicle which undergo multi-level coupling, and build the criterion of the domain where the transformation between kinetic energy and potential energy and the change from plane instability to spatial instability can be controlled; To propose and validate the ground driving/braking force accuracy control method by using the wheel-motor torque feed-forward compensation; To build a rolling stability decoupling control theory based on the coordinated allocation of the torque of four wheels with distributed driving and electric-hydraulic brake. This study will lay a theoretical foundation for the solution of electric wheel-drive vehicle spatial instability problem.

电动轮驱动汽车具有结构紧凑、传动高效和控制灵活的优点，但其在不平路面上的瞬态转向驱/制动过程中簧下动载冲击过大，极易导致车轮跳起和路面附着力丧失，从而引发整车激转乃至侧翻等空间失稳问题。目前国际上尚未对这一演化过程的动力学机理进行理论揭示，也缺乏对其空间稳定性控制的系统解决方案。为此，本项目拟建立涵盖路面-电动轮-悬架-车身的整车控制用多维非线性动力学模型，分析轮毂电机力矩波动、制动器压力脉动、悬架空间运动约束以及轮胎延迟与包容特性对路面附着力的综合影响；揭示多层次耦合作用下整车的空间失稳演化机理，建立其由平面失稳向空间失稳进行动/势能转化的可控域判据；提出并验证利用轮毂电机转矩进行前馈补偿的地面驱/制动力精确控制方法，构建基于四轮分布式驱动与电液复合制动协调分配的侧倾稳定性解耦控制理论体系。本项研究将为解决电动轮驱动汽车的空间失稳问题奠定理论基础。

电动轮驱动汽车具有结构紧凑、控制灵活和传动高效的优点，整车的动力学性能较集中式驱动汽车具有大幅提升，但其在不平路面上的瞬态转向驱/制动过程中簧下动载冲击过大，极易导致车轮跳起和路面附着力丧失，从而引发整车激转乃至侧翻等空间失稳问题；此外，如出现单侧驱动系统意外失效，整车将丧失稳定性和持续高速行驶能力。为了对电动轮驱动汽车不平路面动载冲击下的空间失稳过程的动力学机理进行理论揭示并对电动轮驱动系统失效进行全方面控制，本项目提出了整车空间稳定性控制和驱动系统失效控制的系统解决方案。本项目建立了涵盖路面-电动轮-悬架-车身的整车控制用多维非线性动力学模型，分析了轮毂电机力矩波动、制动器压力脉动、悬架空间运动约束以及轮胎延迟与包容特性对路面附着力的综合影响；揭示了多层次耦合作用下整车的空间失稳演化机理，建立了其由平面失稳向空间失稳进行动/势能转化的可控域判据；提出并验证了利用轮毂电机输出力矩进行误差前馈补偿的地面驱/制动力精确控制方法，构建基于四轮分布式驱动与电液复合制动协调分配的侧倾稳定性解耦控制理论体系；针对单侧系统失效提出了电液复合制动控制方法，发明了可以实现分布式驱动与集中式驱动一体化集成的双模耦合驱动系统并提出了变模冲击的抑制方法，从而通过结构冗余保证了仅利用单侧正常工作电机驱动整车高速行驶的能力；为了提高电动轮驱动车辆的持续行驶能力，基于双模耦合驱动系统发明了同轴混联插电式混合动力汽车的多模耦合驱动系统，完成了参数匹配与优化，为电动轮驱动技术与混合动力技术的综合运用提供了一套可行方案。本项研究为解决电动轮驱动汽车的空间失稳问题奠定理论基础，为电动轮驱动技术的实际应用提供了多种途径，对于提成车辆电动化水平具有重要的理论价值和实际意义。