Zhengang Shi

Active Magnetic Bearings (AMB) are widely utilized in high-speed rotating machinery due to their frictionless operation, low energy consumption, and controllable stiffness and damping. However, the rotor drops onto auxiliary bearings (AB) caused by AMB overload or failure triggers intense nonlinear impacts and frictional heat accumulation, posing a severe threat to system safety. Current simulations of this process face significant challenges, particularly regarding the numerical stability and accuracy of the dynamic response under nonlinear transient impact conditions. To address these issues, this paper establishes a nonlinear dynamic model of a horizontal AMB-supported rigid rotor-AB system. The elastic hysteresis torque between the rotor and the AB inner race is introduced innovatively, which effectively suppresses the non-physical divergent backward whirl commonly encountered in high-speed simulations, thereby enhancing computational stability. Furthermore, a nonlinear equivalent viscous damping theory is employed to characterize the normal contact force, which is consistent with the physical reality that normal energy is not conserved during the drop impact. A high-stiffness and high-damping linear spring model is proposed for efficient tangential contact force calculation, simplifying the originally complex state-switching logic while balancing computational efficiency and precision. This study provides an effective analytical tool for understanding the dynamic impact behavior of rotor drop, offering significant theoretical value and engineering implications for the design and reliability assessment of AMB protection systems.

Multisensor information fusion techniques based on deep learning are crucial for machinery fault diagnosis. However, there are two major issues in previous research. First, the relationship between multisensor samples is disregarded, which is important to enhance the diagnostic performance. Second, the structure of the fusion algorithm becomes extremely complex with prolonged training when dealing with machinery equipped with a large number of sensors. To address the aforementioned two issues, our study proposes a new multisensor fusion mechanism that fuses multisensor information on hypergraphs, by building a single-sensor fusion hypergraph and a multisensor fusion hypergraph in the sensor space to embed the fault samples as nodes. In addition, a dual-branch hypergraph neural network is designed to compute the two hypergraphs to obtain the feature representation of the samples and diagnose faults. The algorithm is validated on two datasets for its performance.

This research investigates the problem of synchronous vibrations suppression in an active magnetic bearing (AMB) system without a rotating speed sensor. The mass imbalance of the rotor is intractable in the AMB system, which will substantially compromise the stability and safety of the system during operation. To realize the unbalance control, rotating speed sensors are commonly employed to gauge the rotating speed. However, the rotating speed sensors cannot operate routinely in special environments. This work proposes an adaptive period iteration control (APIC) algorithm combined with a three-module real-time rotating speed estimator (TMRRSE) to address the above problems. The TMRRSE uses the positions of the rotor at different moments to calculate the rotating speed. And it can also adjust the anti-noise performance and precision by its parameters and has significant tracking performance. The APIC algorithm can adaptively suppress the current vibrations based on the period iteration strategy. In addition, the stability of the overall control scheme is demonstrated using the Lyapunov method. Finally, simulation and experimental results demonstrate the effectiveness of the overall control scheme.

The axial bearing does not contain a laminated piece; so its dynamic performance is poor and often does not meet the load requirements. To accurately assess axial bearing performances during the design stage, it is necessary to accurately calculate the dynamic characteristics of the bearing, including amplitude, phase, and other parameters. Traditional studies have generally used the magnetic circuit method (MCM) or the finite element method (FEM) to analyze the dynamic performance of bearings, and few experimental measurements are carried out. Some experiments use a Guess meter to measure the magnetic field at local locations without directly measuring the electromagnetic force. In this paper, the dynamic force of axial bearing is measured by experiments, and the finite element calculation with Ansys Maxwell is carried out to study the influence of the gap, resonance, and other factors on the electromagnetic force. The comparison reveals a significant error in the calculation method using the initial gap because the gap between the stator and rotor changes with the dynamic force in the experiment. In this paper, the calculation method of “analyzing the dynamic performance of the bearing with the actual gap after the DC component is energized as the calculation gap” is proposed, which significantly reduces the calculation error and can ensure that the calculation error of amplitude and phase within 100 Hz is less than 5%. The method is of great significance for the engineering application of axial electromagneticbearings.

The Active Magnetic Bearing (AMB) technology is introduced in the High Temperature Reactor-Pebble-bed Modules (HTR-PM) demonstration nuclear power plant, which is being constructed in Shandong province, China. The auxiliary bearing is one of the most important components guaranteeing the reliability of the AMB. It also has an important impact on the reliability of the whole reactor system. Compared with the traditional auxiliary bearing, a novel one proposed by the authors has a smaller impact force and the rotor center orbit is much more concentrated during the rotor drop. This paper establishes an analytical model of drop of rolling-sliding integrated auxiliary bearing to analyze the above phenomena. Based on the Hertz contact theory, the complex structure inside the rolling bearing is simplified through a spring damping model. The overall impact model of the rolling-sliding integrated auxiliary bearing is established. Then, according to the structural characteristics of the rolling-sliding integrated auxiliary bearing, the tangential force inside the rolling- sliding integrated auxiliary bearing can be obtained by applying the angular momentum theorem. Finally, a four-degree-of-freedom horizontal rotor drop model is established to analyze and calculate the center orbit and motion state of the rotor. The analytical model is helpful in the selection and design of auxiliary bearing for AMB. In further research this contact model can be used to calculate the center orbit and contact forces in the application of the rolling-sliding integrated auxiliary bearing.

Presents corrections to the above named paper.