新型电动拖拉机用磁悬浮储能飞轮转子非线性控制策略研究

Active magnetic bearing (AMB) supported energy storage flywheels, environmentally friendly mechanical energy storage devices, applied in electric tractors as power batteries along with existing lithium batteries and lead-acid batteries, can greatly improve the energy efficiency and overall performance of electric tractors. Since the harsh working conditions such as complex operating environments, frequent variation of resistance and load, the AMBs supporting the flywheel rotor need to provide greater electromagnetic force to suppress the vibration of the flywheel rotor, which leads to magnetic saturation of the magnetic material in AMBs and consequently the nonlinear electromagnetic force response. Design of controllers that operate the AMBs in the presence of magnetic saturation is known to be a challenging task. The existing control designs for AMB-supported energy storage flywheel rotors cannot ensure stable operation of the system in the nonlinear region of the magnetic material flux density. In this project, by analyzing the rotor dynamic characteristics of the AMB-supported energy storage flywheel under the operating conditions of electric tractors, a nonlinear control design based on the convex hull representation of the saturation nonlinear function is proposed, and the robustness of the resulting controller with respect to model uncertainties, external disturbances and time delay is analyzed. Simulation and experimental verification of the theoretical results will also be carried out. This project thus provides theoretical and technical foundations for the application of AMB-supported energy storage flywheels in electric tractors.

将磁悬浮储能飞轮这种绿色环保的机械储能装置应用在电动拖拉机上，与现有的锂电池和铅酸电池一起作为动力电池，能够极大提高电动拖拉机的能源利用率和整体性能。由于电动拖拉机上的磁悬浮储能飞轮面临着运行工况复杂、阻力和负载实时变化等苛刻的工作条件，支承飞轮转子的磁悬浮轴承需要提供更大的电磁力来抑制飞轮转子的振动，导致磁悬浮轴承磁性材料发生磁饱和现象和电磁力的非线性问题，使得控制器难以设计。现有的对磁悬浮储能飞轮转子的控制设计均不能保证系统在磁性材料磁感应强度的非线性区域高效运行。本项目通过研究电动拖拉机运行工况下磁悬浮储能飞轮转子动力学问题，设计基于饱和非线性函数凸包络表示的非线性控制器，分析控制器对模型不确定性、外界扰动、时滞的鲁棒性，并进行仿真和实验验证，旨在解决确保电动拖拉机用磁悬浮储能飞轮在系统的非线性区域内可靠运行的控制问题，为磁悬浮储能飞轮在电动拖拉机上的应用提供理论依据和技术基础。

为研究新型电动拖拉机用磁悬浮储能飞轮的非线性控制问题，本研究主要完成了以下研究工作：通过设计电动拖拉机用磁悬浮储能飞轮的结构及驱动方法，建立磁悬浮储能飞轮动力学模型以及对支承储能飞轮转子的磁悬浮轴承进行电磁特性分析，得到电动拖拉机用磁悬浮储能飞轮非线性耦合动力学模型；基于电动拖拉机的运行工况，采用辅助矩阵凸包表示法设计可在非线性区域运行的磁悬浮储能飞轮控制器，并针对具有模型不确定性和执行器饱和系统进行非线性PID控制器设计，包括算法理论设计和数学证明，并基于磁悬浮储能飞轮控制中的基本单元模型进行可行性仿真验证，同时针对模型不确定性、时变系统以及开环系统增加非线性项这三种情况，验证控制算法的有效性；针对具有输入时滞二维不确定非线性系统设计PID鲁棒控制器，包括算法理论提出、设计和数学证明，基于支承飞轮转子的磁悬浮轴承单元模型进行了仿真验证，并基于模型不确定性和时变系统进行该算法的鲁棒性验证。此外，为提高磁悬浮储能飞轮的存储能量和效率，我们还对飞轮阵列储能系统进行了分布式协同控制器设计，仿真实验结果证明了控制设计的有效性。