Sun Huaqiang, Liang Zhiqin, Cheng Baixin
School of Mechanical and Automotive Engineering, Liaocheng University, Liaocheng 252059, China.
Sensors (Basel). 2025 Jul 21;25(14):4517. doi: 10.3390/s25144517.
At present, the redundant structures are one of the most effective methods for solving magnetic levitation bearing coil failure. Coil failure causes residual effective magnetic poles to form different support structures and even asymmetrical structures. For the magnetic bearing with redundant structures, how to construct the electromagnetic force (EMF) that occurs under different support structures to achieve support reconstruction is the key to realizing fault tolerance control. To reveal the support reconstruction mechanism of magnetic bearing with a redundant structure, firstly, this paper takes a single-degree-of-freedom magnetic suspension body as an example to conduct a linearization theory analysis of the offset current, clarifying the concept of the current distribution matrix (CDM) and its function; then, the nonlinear EMF mode of magnetic bearing with an eight-pole is constructed, and it is linearized by using the theory of bias current linearization. Furthermore, the conditions of no coils fail, the 8th coil fails, and the 6-8th coils fail are considered, and, with the maximum principle function of EMF, the corresponding current matrices are obtained. Meanwhile, based on the CDM, the corresponding magnetic flux densities were calculated, proving that EMF reconstruction can be achieved under the three support structures. Finally, with the CDM and position control law, a fault-tolerant control system was constructed, and the simulation of the magnetic bearing with a redundant structure was carried out. The simulation results reveal the mechanism of support reconstruction with three aspects of rotor displacement, the value and direction of currents that occur in each coil. The simulation results show that, in the 8-pole magnetic bearing, this study can achieve support reconstruction in the case of faults in up to two coils. Under the three working conditions of wireless no coil failure, the 8th coil fails and the 6-8th coils fail, the current distribution strategy was adjusted through the CDM. The instantaneous displacement disturbance during the support reconstruction process was less than 0.28 μm, and the EMF after reconstruction was basically consistent with the expected value.
目前，冗余结构是解决磁悬浮轴承线圈故障最有效的方法之一。线圈故障会导致残余有效磁极形成不同的支撑结构，甚至是非对称结构。对于具有冗余结构的磁轴承，如何构建在不同支撑结构下产生的电磁力以实现支撑重构是实现容错控制的关键。为揭示具有冗余结构的磁轴承的支撑重构机理，首先，本文以单自由度磁悬浮体为例对偏置电流进行线性化理论分析，阐明电流分布矩阵（CDM）的概念及其作用；然后，构建八极磁轴承的非线性电磁力模式，并利用偏置电流线性化理论对其进行线性化。此外，考虑无线圈故障、第8个线圈故障以及第6 - 8个线圈故障的情况，利用电磁力的最大原理函数得到相应的电流矩阵。同时，基于CDM计算出相应的磁通密度，证明在三种支撑结构下均可实现电磁力重构。最后，结合CDM和位置控制律构建了容错控制系统，并对具有冗余结构的磁轴承进行了仿真。仿真结果从转子位移、各线圈中出现的电流值和方向三个方面揭示了支撑重构的机理。仿真结果表明，在八极磁轴承中，本研究最多可在两个线圈发生故障的情况下实现支撑重构。在无线圈故障、第8个线圈故障以及第6 - 8个线圈故障这三种工况下，通过CDM调整电流分布策略。支撑重构过程中的瞬时位移扰动小于0.28μm，重构后的电磁力基本与预期值一致。
