Introduction to the International Symposium on Magnetic Bearings


The International Symposium on Magnetic Bearings (ISMB) is an annual event that brings together leading researchers, engineers, and industrialists from around the world to discuss current and emerging technologies related to magnetic bearings. The event provides an opportunity to exchange ideas, present and discuss research results, and foster collaboration between scientists and engineers in the field.  

The event is hosted by the Institute of Electrical and Electronics Engineers (IEEE) Magnetics Society and is held in a different country every year. The topics discussed at ISMB range from theoretical analysis and design to practical applications of magnetic bearings. The symposium also covers recent developments in materials, instrumentation, and control systems related to the use of magnetic bearings. 

Many team members of SpinDrive have been active in the research field in the past. SpinDrive has world-class experts who have been actively extending their knowledge around active magnetic bearings. International Symposium on Magnetic Bearings ISMB is a conference that is specifically dedicated to magnetic bearing research and implementation. The next ISMB will be the 18th event and it will take place at Palais des Congrès in Lyon from July 18th to 21st, 2023. The aims of ISMB18 are to promote scientific and technological exchange and to enhance the understanding and dissemination of magnetic bearing technology worldwide. The ISMB is the major meeting for academic and industrial researchers from all over the world. 


SpinDrive at the 18th ISMB

During the 18th ISMB, the SpinDrive team will present our study on the Control and Commissioning of Active Magnetic Bearing (AMB) Systems for a High-speed 1 MW Turbo Blower. This study is based on a user case at Runtech Systems, a company that manufactures turbo blowers. A turbo blower is a type of rotating equipment typically used in industrial and manufacturing settings to ide large volumes of air or gas driven by a high-speed electric motor. Turbo blowers can provide high energy efficiency and deliver a constant flow rate, making them a popular choice in many industrial applications, e.g. in pulp and paper. 

This case describes how limited observability and controllability of the AMB system were solved during the 1 MW turbo blower commissioning. The robust model-based controller takes into account speed dependent model, foundation resonances, and external disturbances to achieve the desired performance. 


Turbo blower equipped with active magnetic bearings

Figure 1. 1 MW turbo blower made by Runtech Systems


Meanwhile, SpinDrive will also present the Magma X800 AMB controller together with our customer reference videos at a booth at the 18th ISMB. 

Magma AMB control units

Figure 2. SpinDrive’s Magma X800 AMB Controller


Publications written by SpinDrive team members in the past

In the past, SpinDrive team members have been contributing to the previous ISMB events proceedings in the following articles including the list of authors, year of publication, title, proceedings and abstract of the article: 

  1. Jastrzebski, R.P., Jaatinen, P. and Pyrhonen, O., 2016, Modelling and control design simulations of Permanent Magnet Flux-Switching Linear Bearingless Motor, Proceedings of ISMB15 

Abstract: For permanent magnet (PM) motor structures in rotating systems, it is typical to retain the magnets in the rotor. This constrains the rotor structure and limits applicability, e.g., for high-speed and high-temperature conditions. Flux-switching PM (FSPM) motors can overcome this limitation. Recently, the FSPM bearingless motors have been developed for special applications. The FSPM concept can be adapted to liner motors. For the linear motors, magnets or windings placed on the mover significantly decrease complexity and cost for longer distances. Still, to separate control of airgap and torque (thrust) two sets of windings or multiphase windings have been required for both rotating FSPM and linear PM machines. The linear FSPM bearingless motor solution, which integrates the magnets, winding structure and all the driving and control electronics on the mover is desired for many applications. However, because of electromagnetic unbalances the machine design is entangled with the control limitations and requirements. We reveal a modelling methodology for accurate derivation of bearingless machine dynamic and static force parameters as a function of airgap, control currents and track position in extended operational range. Model-based control simulations based on the accurate derived plant models determine the achievable machine performance and levitation limitations. The design and modelling methodology is general and can be applied to different PM bearingless motors. In the case study of linear FSPM bearingless motor the airgap control is possible in the equivalent to classical AMBs manner where it is independent from the thrust control. 

2. Jaatinen, P., Sillanpaa, T., Jastrzebski, R.P., Sikanen, E. and Pyrhonen, O., 2016, Automated Parameter Identification Platform for Magnetic Levitation Systems: Case Bearingless Machine, Proceedings of ISMB15  

Abstract: This paper presents automated platform that can be used to identify parameters of magnetic levitated systems. Identification platform itself consists of 3-axis force measurement sensors and 2-axis stepper motors driven linear ball screw tracks. This kind of construction enables to measure the force produced by electromagnets in any angle and in any position in the air gap. Measurement system is controllable so the identification process can be automated. As a case study, self and mutual inductances of an interior permanent magnet bearingless machine are identified for the motor control purposes. Force sensors are used to measure the unbalance magnetic pull inflicted by the permanent magnets embedded in the rotor. Automated measuring procedure is used to determine self and mutual inductances of the bearingless motor. System functionality is validated by comparing the measured magnetic pull results to FEM analysis and inductance measurement to different prediction method based on standard motor drive identification process. Based on achieved results presented automated platform can be used to identify parameters of magnetically levitated system. 

3. Jastrzebski, R.P., Jaatinen, P. and Chiba, A., 2016, Efficiency of buried permanent magnet type 5kW and 50kW high-speed bearingless motors with 4-pole motor windings and 2-pole suspension windings, Proceedings of ISMB15 

Abstract: This work focuses on loss prediction for varying operation conditions of the high-speed buried-type interior permanent magnet (IPM) bearingless motors. The investigated motors are 5 kW and 50 kW units configured as twin motor sets, which provide radial suspension and motoring in 5 degrees of freedom levitated rotor systems with the maximum speed of 30000 r/min. The maximum output power of studied rotor systems is 10 kW and 100kW, respectively. Additionally, the power factors of motor and suspension windings as well as inductance maps for various operating conditions are studied. The magnetic field 2-dimentional transient section analysis and time stepping are applied. The selected results are compared with the measured values. In the loss calculation various rotor and stator iron losses, resistive losses, windage losses and additional losses are taken into account. Efficiency maps and power factor estimation are valuable for application of electrical machines. These studies have been performed using various methods for classical motors and generators but are uncommon for bearingless motors working with different loading conditions. The comprehensive efficiency map prediction of the high-speed IPM bearingless motors for different suspension loading is presented for the first time. The variations of motor inductances for different rotor angles and current amplitudes are derived. The differences in results between the machines with the same geometry but different power are discussed. 

4. Vuojolainen, J., Smirnov, A., Jastrzebski, R., Sillanpaa, T., Ghalamchi, B. and Hartikainen, T., 2016, Updating the model of a rotor with surface mounted permanent magnets in an active magnetic bearing rotor system, Proceedings of ISMB15  

Abstract: In this publication, the finite element method (FEM) model of a rotor of permanent magnet (PM) machine with surface mounted permanent magnets is updated. Typically rotors are modeled with FEM, but the model is still only an approximation of the real rotor. The rotor is constructed from number of different elements and have a complex geometry. Electrical machine part might have slits, surface mounted or embedded permanent magnets. Elements are often connected with shrink fits and this leads to the properties discrepancy compared to the elements described with Timoshenko beam theory. In the work, specific elements are selected as uncertain based on engineering experience and the elasticity values of these elements is updated. Experimental data is obtained with AMB system identification and then the frequency difference in the resonance and anti-resonance frequencies between the experimental data and FEM-model is minimized. When the frequency difference has been minimized, the updated FEM-model corresponds better to the experimental data. The updated model is utilized for controller synthesis procedure to improve performance of the control system. An AMB PM machine with surface mounted permanent magnets was used to test the rotor model update procedure. The procedure allowed to fit the model to the experimental data with accuracy of 56.57 %. 

5. Jastrzebski, R.P., Sillanpaa, T., Jaatinen, P., Smirnov, A., Vuojolainen, J., Lindh, T. and Laiho, A., 2016, Automated Design of AMB Rotor Systems with Standard Drive, Control Software and Hardware Technologies, Proceedings of ISMB15 

Abstract: Industrial applications of active magnetic bearings (AMBs) technology have been continuing to grow for over 4 decades. However, the volume and cost reduction for consumer products are still lower than industrial potential. Particularly, bearing design to match the application, control design, commissioning, control tuning, electronics design and scaling of VA rating to match the bearings make the significant contribution to overall cost of new AMBs. This paper describes how to design and implement an industrial 5 degrees of freedom AMB suspension and model-based control for rotating systems quickly and efficiently. The presented solution leverages the existing commercialized drives and automation components for making the AMB products. With the automated analytical design of AMB actuators and control in respect to design constrains the design & engineering of the product are completed. This leads to easier scalability, standardization, lead-time reduction, and broadening the application area. 

6. Smirnov, A., Uzhegov, N., Sillanpaa, T., Pyrhonen, J. and Pyrhonen, O., 2016, Design and evaluation of high-speed solid rotor induction machine supported by AMBs with a multidisciplinary tool, Proceedings of ISMB15 

Abstract: For high-speed electrical machines compact design is one of their advantages and further system integration is required to increase a system efficiency. A growing level of the technical system integration may cause additional design problems and increase design time. In this work the design procedure and design optimization of high-speed electrical machines supported by Active Magnetic Bearings (AMBs) are described. First, the design of the high- speed induction motor, bearings, and rotor are analyzed. Then, the boundary conditions and optimization variables are selected based on the key system performance indicators. The optimization variables include, for example, rotor outer diameter, number of rotor bars, slit depth ratio, and some other. Finally, an optimization procedure is presented, including objectives for the optimization procedure, fitness function, and selected algorithm. The pre- sented procedure is tested with an example of high-speed induction machine with solid rotor equipped with AMBs. Based on the optimization results the prototype is constructed. An implementation of the optimization procedure prevented extra iterations during the final design stage and reduced total design time. With slight modifications this procedure is applicable for other types of high-speed electrical machines supported by AMBs. 

7. Smirnov, A., Uzhegov, N., Hartikainen, T. and Pyrhonen, J., 2016, Design Aspects of AMBs for High-Speed Permanent Magnet Synchronous Machine, Proceedings of ISMB15 

Abstract: Distributed power generation is nowadays one of the global trends. Compared with the centralized power gen- eration there is no need to transmit and regulate electricity network in the case of distributed generation. These advantages can be critical for many electricity consumers. Distributed power generation using microturbines is an alternative to the commonly used combustion engines. These installations increase total system efficiency and enable operation at the low partial loads. In this paper the design aspects of a high-speed permanent magnet syn- chronous machine (PMSM) equipped with active magnetic bearings (AMBs) are considered. The structure of the permanent magnet generator is explained and its parameters are presented and discussed. This paper concentrates on the additional magnetic pull created by the PMSM at standstill. This situation creates extra forces and set extra requirements to AMBs. The method to avoid unnecessary magnetic bearing overdimensioning using electrical machine control system is described. An influence of the unbalanced magnetic pull on the active magnetic bearing control is presented. The uneven distribution of the force leads to additional complexity for the controller synthesis. The rotating reference frame for the control problem formulation is discussed. 

8. Sikanen, E., Jastrzebski, R., Jaatinen, P., Sillanpaa, T., Smirnov, A., Sopanen, J. and Pyrhonen, O., 2016, Mechanical Design of Reconfigurable Active Magnetic Bearing Test Rig, Proceedings of ISMB15 

Abstract: In this study, considerations of a mechanical design of a reconfigurable active magnetic bearing (AMB) test rig and some of its interchangeable modules are reviewed. The manufacturing of modules, assembly, measurements of mechanical accuracies and their influence on electrical and control requirements of the active components are analyzed. Numerical simulations for 10 kW 30000 rpm high-speed rotor of induction motor are performed for studying purposes of rotor dynamics and mechanical stresses of various changeable rotor sleeve parts. Impor- tant part of high-speed AMB system are mechanical backup bearings. Additional sub-modules are designed for changeable backup bearings for further rotor dropdown experiments. Also, reference sensors required by the AMB control system are fitted into own sub-module in order to enable testing of various sensor designs. Experimental measurements are performed in order to study rotor dynamics and mechanical accuracies of modular test rig design. Some operational results during commissioning phase are presented and discussed. The benefits and challenges of using a modular design are discussed. The scope of this paper is in mechanical design, therefore no detailed description of designed AMBs and control system is presented. 

9. Smirnov, A., Pesch, A., Wroblewski, A., Pyrhönen, O. and Sawicki, J.T., 2014, Feedback Compensation of Tool Deflection in a High Speed AMB Machining Spindle, Proceedings of ISMB14 

Abstract: This paper describes a method for compensation of tool tip deflection in a high-speed, magnetically levitated, machining spindle. The proposed method utilizes measurements from the AMB sensors to estimate forces and calculate the resulting tool deflections. The deflections are then compensated online with a feedback signal that changes the loaded tool tip’s position. The modeled results show significant performance improvements, which are experimentally validated. 

10. Jastrzebski, R., Smirnov, A., Lin, Z., Pyrhönen, O. and Allaire, P., 2012, Extended Kalman Filter Applied to an AMB System with Strong Magnetic Saturatio, Proceedings of ISMB13  

Abstract: The main aim of the paper is to operate an AMB system inside the magnetically saturated region. We investigate how to stabilize a highly nonlinear AMB system with the actuator magnetic saturation by estimating the system states and parameters of the unconstrained bearing in real time. The stabilization is achieved by a combination of the controller and the extended Kalman filter to estimate the states of the plant. In the extended Kalman filter, the magnetization behavior has been modeled by using low-order piecewise polynomial approximation. The extended Kalman applied to the AMB system introduces an additional challenge because of the computational burden, numerical stability when computing the inverse of the innovation covariance matrix, and the non-continuous derivative in the computed Jacobeans. Feasibility of different control configurations is examined. As the case study we use the 1 DOF balancing beam model. The proposed solution for the system operation in the magnetic saturation provides such benefits as: the reduced size and costs of bearings, improved robust performance and stability, and an increased controllability region with respect to control variables. 

11. Hynynen, K.M., Jastrzebski, R.P. and Smirnov, A., 2010, Experimental Analysis of Frequency Response Function Estimation Methods for Active Magnetic Bearing Rotor System, Proceedings of ISMB12 

Abstract: System identification can be used in automated retuning of an active magnetic bearing (AMB) rotor system during commissioning. In the case of good signal-to-noise ratio (SNR), the identification measurements are more time effective using multisine excitation than stepped sine excitation. A multisine signal contains selected frequencies in the desired frequency range. Since in multisine excitation the signal distributes the power over F frequencies, the SNR of the measurement deteriorates. The SNR is improved by averaging the measured frequency response function (FRF) over several measurements. The purpose of this study is to investigate the suitability of different frequency response function estimators for an AMB rotor system identification. The results show that the most accurate estimator for this setup with non-synchronous measurements and the excitation used, is a joint-input-output estimator. 

12. Smirnov, A., Jastrzebski, R.P. and Hynynen, K.M. 2010, Gain-Scheduled and Linear Parameter-Varying Approaches in Control of Active Magnetic Bearings, Proceedings of ISMB12 

Abstract: In this paper Linear Parameter Varying, gain-scheduled and robust approaches for a controller synthesis are considered in an application for a highly gyroscopic system. A transient during a rotor start up and a steady state disturbance attenuation are evaluated. Based on these measurements a comparison of different control approaches is done. 

13. Jastrzebski, R.P., Hynynen, K.M. and Smirnov, A., 2010, Uncertainty Set, Design and Performance Evaluation of Centralized Controllers for AMB System, Proceedings of ISMB12 

Abstract: In this paper an industrially recognized modal control approach, a linear-quadratic-Gaussian (LQG) control, and an H8 control designs are compared using automated weights tuning based on a genetic algorithm. The robust stability analysis is carried out based on the uncertainty set, which comprises parametric and nonparametric uncertainties. The uncertainty set is updated to be compliant with the measured frequency responses of the test rig. The studied combination of the uncertainties proves too conservative for the direct application in the H8 control synthesis. However, a robust stability of the controllers synthesized using the nominal plant can be verified using µ-analysis and the very uncertainty set that cannot be used for the controller design directly. It is demonstrated that for the rigid rotor without strong gyroscopic coupling all of the control approaches result in a similar performance. For the more slender rotor with an additional disc and the dynamics dependent on the rotational speed the best results are achieved by the LQG and H8 controllers. When no gain scheduling is applied, the modal control results in the unstable system. 


More info

You can find more information about the 18th ISMB here: 18th International Symposium on Magnetic Bearings – ISMB18 – If you are interested in any of these topics, feel free to contact SpinDrive to discuss these research results.


The International Symposium on Magnetic Bearings




Janne Heikkinen portrait

Author: Dr. Janne Heikkinen