基于模态力约束的平面电机振动抑制研究

随着轻量化设计的需求,磁悬浮平面电机结构质量与柔性之间矛盾凸显,使得低阶模态引起的振动将严重制约其纳米精度的生成及控制系统稳定性。目前,振动抑制研究中的控制算法较为复杂,难以有效应用于工程实际。针对此问题,该文提出基于模态力约束的振动抑制方法。该方法针对垂向电机推力分配策略,在受力方程的基础上,以模态力之和等于0作为约束,利用力分配特解使各垂向电机的模态贡献相互抵消,从物理本质层面解决柔性振动问题。针对平面电机第一阶模态,采用模态力约束方法后,辨识模型在该阶模态处表现出刚体特性,且垂向z的定位误差减小至5 nm,验证了该方法对振动抑制的有效性。

基于分布式驱动电动汽车的再生制动策略设计及优化

针对前轴集中电机驱动、后轴轮毂电机驱动的分布式驱动汽车,设计了再生制动策略(策略1)。根据再生制动时的动力传动过程提出了发电系统总效率的概念,并根据其最高得到最优的前后电机力分配系数,在欧洲经济委员会(ECE)法规的约束下,设计了再生制动经济性优化策略(策略2)。考虑到装备了防抱死制动系统(ABS)的车辆在制动强度较小时可优先使用后轴电机进行再生制动,提出了低制动强度下的经济性优化策略,以充分利用发电系统的高效区(策略3)。分析并说明了所提出的策略对制动感觉的影响不大。仿真结果表明,三种策略的能量消耗分别减少14.05%,15.04%和16.64%。

Connecting Wind Turbine Generator to Distribution Power Grid--A Preload Flow Calculation Stage

A distribution grid is generally characterized by a high R/X （resistance/reactance） ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in such a way that power flows from transmission system via distribution system to consumers. But in a situation when wind turbines are connected to the distribution grid, the power source will change from one source to two sources, in this case, network is said to be active. This may probably have an impact on the distribution grid to whenever the wind turbine is connected. The best way to know the impact of wind turbine on the distribution grid in question is by carrying out load flow analysis on that system with and without the connection of wind turbines. Two major fundamental calculations： the steady-state voltage variation at the PCC （point of common coupling） and the calculation of short-circuit power of the grid system at the POC （point of connection） are necessary before carrying out the load flow study on the distribution grid. This paper, therefore, considers these pre-load flow calculations that are necessary before carrying out load flow study on the test distribution grid. These calculations are carded out on a test distribution system.