Papers by Keyword: Magnetic Bearing

Abstract: New Hybrid (HB) type Active Magnetic Bearing (AMB) is proposed in this paper. It is intended to apply to high speed turbo machinery. This magnetic bearing is easily controlled by a standard linear power amplifier. The proposed magnetic bearing is analyzed and designed through Finite Element Method (FEM). The designed characteristics are compared with the standard electro-magnet type magnetic bearing. The results show good characteristics of high efficiency, good dynamic property and easy manufacturing. The proposed magnetic bearing is fabricated and the simple tests are carried out.

Abstract: Chatter vibrations and tool deflection are common challenges in metal cutting processes. In roughing operations, it is often the occurrence of chatter vibrations which limits the productivity. While finishing, when tolerances are small, the tool deflection can lead to violating tolerances and thus producing scrap parts. Beside the tool and tool holder, it is also the guidance system, especially in the z-axis, which influences the aforementioned phenomena. In this paper the influence of an electromagnetic guided z-axis is presented. It is focused on the influence of the high damping and the high static stiffness of the guide. Further benefits of this technology are outlined.

Abstract: This paper designs an intelligent fuzzy PID controller of electromagnetic bearing for axial artificial heart pump (AAHP) to achieve re-stable suspension and quick response performance. and Matlab/Simulink is employed to simulate floating process of the rotor and the process of response to displacement disturbance. The simulation results show that the floating overshoot can be inhibited effectively, with the fuzzy PID controller. Fuzzy PID controller can respond to sudden displacement disturbance quickly. Then analyze the simulation waveforms of Fuzzy PID controller and traditional PID controller, verify that the fuzzy PID controller can overcome the shortcomings of traditional PID controller, and increase the control precision of the system and the robustness of the system.

Abstract: In order to prevent damage caused by instantaneous power failure to high-speed equipment, the thermoelectric energy conversion system for controller of magnetic bearing is studied. The heat source is used by the power loss of supply modules and the cold source is used by heat conduction aluminum block. The semiconductor thermoelectric generator produces direct-current working voltage between heat source and cold source. The overall design method of the energy conversion system is presented. The theory and design of circuits to thermoelectric energy generator, voltage regulator and charging for lithium polymer battery are analyzed. The experiment results show that this thermoelectric energy generator system is feasible and effective. The circuit can be adapted to change in output power due to temperature difference at both ends of the thermoelectric module. It achieves energy storage of the recovery from thermoelectric generator.

Abstract: To effectively reduce friction torque and start-up wind speed, magnetic bearing was applied to the small-scale wind turbine. Load analysis is the primary task of the design for magnetic bearing in wind turbine. Based on a typical blade model, the aerodynamic performance of the impeller was simulated using Computational Fluid Dynamics (CFD) method. The characteristics and differences of the impeller’s aerodynamic performance under different wind speeds were analyzed and the aerodynamic loads were calculated as well. Moreover, the bearing capacity of magnetic bearing was calculated according to the forces on the spindle. A kind of permanent magnetic bearing (PMB) was designed for the radial supporting of the spindle in wind turbine. A prototype of the small-scale maglev wind turbine (SMWT) was presented, which provides some basis for the application of magnetic bearings in wind turbines.

Abstract: Magnetic suspension flywheel system is the actuator of spacecraft in high accurate position control, which requires the employed magnetic bearing possessing advantages of compact structure, small volume, light weight, low power loss, high efficiency and so on. A novel axial hybrid magnetic bearing in magnetic suspension flywheel is proposed, and the bias magnetic flux is provided with a permanent magnet ring. The cost and total volume of this structure can be reduced, which is especially suitable for magnetic suspension flywheel system. The structure and working principle of the axial magnetic bearing are explained, the mathematical expressions of the maximum bearing capacity are obtained, the detailed process of parameter design is presented, and the flux and maximum bearing capacity of the hybrid magnetic bearing are analyzed by using finite element analysis software. The analysis results validate the correctness of parameter design on the axial hybrid magnetic bearing.

Abstract: A linearization control research based on α-th order inverse system method has been developed for an axial hybrid magnetic bearing, which is a nonlinear system. The configuration of the axial hybrid magnetic bearing is briefly introduced, the working principle of the hybrid magnetic bearing is analyzed, and then the suction equations are set up. Based on expounding of α-th order inverse system method, and aiming at dynamics model of the axial hybrid magnetic bearing, the feasibility of linearization control is discussed in detail, the linearization control arithmetic based on α-th order inverse system method is deduced, and then close system controller is designed. Finally, the simulation system is set up with MATLAB software. The step response of system, the start up displacement curve of rotor and the performance of anti-disturbance of system are simulated. The simulation results have shown that the α-th order inverse system control strategy can realize accurate linearization for nonlinear mathematical model of the axial hybrid magnetic bearing, and the designed close control system has good dynamic and static performance.

Abstract: The self-sensing magnetic bearing can reduce the cost and the axial size of the magnetic bearing and increase its reliability. A mixed-kernel least squares support vector machines (LS-SVM) forecasting model is proposed for self-sensing technique of a hybrid magnetic bearing. The structure and mathematical model of the radial-axial hybrid magnetic bearing are introduced. Based on the principle of the mixed-kernel LS-SVM, the nonlinear forecasting model between the current and the displacement which realizes the displacement self-sensing control is built through genetic algorithm. Simulation has done to verify the validity and feasibility of proposed method.

Abstract: For magnetic bearing system with characteristics of zero damping, negative stiffness and nonlinearity, this paper put forward a method of inverse control based on the fuzzy inverse model. The fuzzy system with fuzzifier and defuzzifier was used as an interpolator to approximate the inverse model of magnetic bearing. Then we connected the fuzzy inverse model in series with the magnetic bearing system to form a generalized pseudo linear plant, and selected a PID controller to control the pseudo linear plant. The fuzzy inverse model and the PID controller together formed an inverse controller to implement the closed-loop inverse control of the system. The simulation results demonstrate that the inverse control can reduce the overshoot, shorten the settling time, and make the rotor levitate in a larger range.

Abstract: Active magnetic bearing (AMB) is a prime component of the more electric aircraft technology that aims at reducing weight and emissions, and augmenting reliability and efficiency for future aircraft. The effect of maneuvering flight on performance of AMB system is investigated. A mathematical model considering maneuver equivalent force is presented and based on the model stability analysis is presented in terms of asymptotical and regional stability. The research result indicts that maneuvering flight has a great influence on system dynamics and stability.