In this paper, a multisurface levitation concept using three permanent magnets (PMs) and one high temperature superconductor (HTS) ring in a levitation configuration is studied to improve stiffness in a superconducting magnetic bearing system. A geometrical rule is defined to select the size of second and third PMs placed over and under the ring HTS to overlap the frozen images of all PMs. For different combinations of the PMs, experiments are realized and levitation forces are measured. Three levitation surfaces case with attractive polarization of the PMs provided the largest levitation force in the experiments.

The goal of this research study is the maximization of the levitation force in a flywheel system by the use of more than one permanent magnet with a single ring-shaped HTS material. An analytical model for the radial stiffness of the ring HTS-PM is derived using the frozen image approach. The experimental works are carried out for different polarizations of the permanent magnets, and radial stiffness values are obtained from the radial force measurements. The rotational test of the flywheel system is also realized for different cases. Finally, natural frequencies of the flywheel superconducting magnetic bearing system are experimentally obtained for different combinations of the permanent magnets using a frequency analyzer.

The active suspension system is an important equipment that isolates the vibrations that may come from outside in a land vehicle. In heavy vehicles, the active suspension system can be used to dampen vibrations in the driver’s cabin. The electromagnetic actuator is used as an active element in suspension system. Traditionally, the use of active suspension systems is mainly on automobiles and the studies related to heavy vehicles like trucks lack enough interest. In this study, dynamic modeling of a three-axle heavy vehicle cabin is performed with a half-car approach and it is aimed to suppress the disruptive effects coming from the road with active electromagnetic actuators. Lyapunov based backstepping control design is expressed in vectorial form for the heavy vehicle system, which is a multi-input multi-output system. To demonstrate the performance of the designed controller, a comparison has been made for the active and passive states for the truck cabin suspension system. The main feature of the applied control method is that it does not require knowing the actuator parameters, the adaptive term can handle the estimate of the actuator parameter. The stability of the proposed system has been proven via Lyapunov based arguments and given simulation works. The results obtained are important to suppress vibration, consequently, decreases the vibration exposure for truck drivers in terms of occupational health and safety aspects.

In this paper, a rotor-permanent magnet inside a ring-shaped superconductor magnetic bearing system is modeled and simulated using a dynamic stiffness approach. Analytical expressions of the stiffness effects are defined on the basis of a magnetic potential obtained with a frozen-image concept. For engineering applications, the rotor dynamics must be considered with the effective stiffness of the ring-shaped superconducting magnetic bearing. In the proposed model, the variation of the stiffness and the dynamics of the rotor are analyzed for some initial angular and translational movements.

Here, a novel flywheel structure is proposed with passive permanent magnet (PM) bearings in the radial and axial directions and an active magnetic bearing (AMB) in the axial direction. In the proposed structure, passive magnetic bearings do not provide a stable magnetic levitation in all directions, but it is possible to maintain the dynamic stability of the flywheel by using AMB in the axial direction. In the proposed bearing structure, radial repulsive magnetic bearings (RMBs) reduce the power consumption with less complexity in the bearing structure but impose disturbance forces that deteriorate the stability of the actively controlled flywheel system. A complete model of the flywheel system is derived and transformed for a control design. A Lyapunov‐based composite adaptive feedback control is designed for maintaining the stability under disturbances and a close convergence to the desired trajectory with fast parameter estimation. The performance of the composite adaptive control was experimentally verified for different cases using the RMB flywheel system. Additionally, a PID control was experimentally verified to demonstrate the usefulness of parameter estimation.