Analysis and design of an ultra-high-speed slotless self-bearing permanent-magnet motor (original) (raw)
Related papers
Analysis and Design of a 300-W 500 000-r/min Slotless Self-Bearing Permanent-Magnet Motor
IEEE Transactions on Industrial Electronics, 2014
Active magnetic bearings enable contactless operation and can therefore be used for supporting rotors spinning at high speeds. However, the rotational speed in conventional reluctance-force-based magnetic bearing topologies is limited, which is mainly due to high rotor losses and limited force control bandwidths. In this paper, a prototype of a self-bearing motor is presented, which overcomes several limitations of state-of-the-art high-speed magnetically levitated electric drive systems. Due to the employed magnetic bearing, the motor can be operated in high-purity or vacuum environments. An analytical mechanical and electrical bearing model is introduced and verified by measurements. Furthermore, a bearing inverter system is designed, and its controller performance is shown. Measurements of spinning levitated rotors up to speeds of 505 000 r/min verify the functionality of the overall system. To the authors' knowledge, this is the highest speed achieved by magnetically levitated electrical drive systems so far.
Analysis and Control of Slotless Self-Bearing Motor
Actuators, 2019
A self-bearing motor (SBM) is an electric motor with a magnetically integrated bearing function, that is, it can provide levitation and rotation simultaneously as a single actuator. This paper presents the design, operating principle and control system for the slotless self-bearing motor (SSBM). In this design, the stator has no iron core but includes six-phase coils. The rotor consists of a permanent magnet and an enclosed iron yoke. Magnetic forces generated by the interaction between stator currents and the magnetic field of the permanent magnet are used to control the rotational speed and radial position of the rotor. In this paper, the torque and radial bearing forces are analyzed theoretically with the aim to develop an improved control system. In order to confirm the proposed control method, an experimental system was constructed and tested. Simulation and measurement results show that the SSBM can work stably in modes such as start, reverse, rotation load and external radial...
DEVELOPMENT OF A MAGNETICALLY BORNE ELECTRICAL MOTOR PROTOTYPE
2000
The magnetic bearing is an electro-mechanical device that maintains the rotor of an equipment magnetically levitated. Besides allowing for a contact less working condition, resulting in a system without mechanical wear, this device presents other advantages, such as self-balancing, vibration control, self-monitoring, possibility of equipment encapsulation and high operation speed, with high reliability and reduced maintenance. Taking these advantages into account, magnetic bearings are becoming technologically competitive in many applications such as turbo-generators, pumps, compressors, fabrication machines, gyroscopes, centrifuges etc. It should be realized that since the absence of friction eliminates the need of lubrication, the magnetic bearings are ideal for airspace applications and for radioactive environments. Moreover, due to this same characteristic, it is an energy-saving device, which is, perhaps, the main reason for its utilization in new equipments. In order to gain a better understanding of this technology, a prototype of an integrally levitated electrical motor has been developed. The mechanical, magnetic and electric conceptions of the bearings have been already described in previous works, including the mechanical engineering considerations related to the design, fabrication and mounting of the magnetic bearings on the equipment. In this work, the successfully design and implementation of the displacement controllers are described. Simulations and experimental results show the static and dynamic performance of the bearings.
Sliding-mode control design of a slotless self-bearing motor
We encourage authors to share their published articles on social network and repositories, such as SSRN, arXiv, academia.edu, ResearchGate, RePEc, Google Scholar, Mendeley, Zenodo, Archive, Slideshare, Linkedin, Facebook, etc., 2022
Scientists have explored and are studying a slotless self-bearing motor, an electric motor with a magnetically integrated bearing function. As a single actuator, it can provide both levitation and rotation. This article will show a slotless self-bearing motor with a stator that does not have an iron core but six-phase coils. A permanent magnet and an enclosed iron yoke make up the rotor. To regulate the rotational speed and radial location of the rotor, magnetic forces created by the interaction between stator currents and the magnetic field of permanent interest are investigated. This research also includes a slotless-bearing motor mathematical model and control approach. This motor is investigated by combining an AC motor with a magnetic drive to achieve the essential design criterion and low cost. The magnetic force and moment characteristics are theoretically analyzed, and a control technique is proposed. Sliding-mode control (SMC) is a control method that is simple, effective and utilized to serve the control system for approaching the reference value, as stated in this study. It's also commonly used to manage the motor's position and speed. The findings were built and evaluated using MATLAB/Simulink confirmed analytical results to prove the recommended control approach.
Permanent magnet bearingless motors: Modelling, design and drive
2017 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD), 2017
In this paper, the authors give a general description of bearingless machines and the origin of the ripples of the levitation force. Magnetic model using spectral analysis of the air-gap flux density is developed to identify the forces ripples and their origins. The authors propose two ways to suppress the force ripples. The first one can be performed during the design process of the machine while the second one can be applied with the supply via a control loop and an active harmonic suppression.
Actuators
The centering guidance forces in self-bearing permanent magnet motors are magnetically integrated with the torque generation windings, and can take place in a single multifunction winding. This radial guidance is usually actively controlled as a function of the rotor position, with the drawbacks associated to actively controlled devices. This article describes how multifunction windings can passively generate electrodynamic centering forces without the need for specific additional electronics, and simultaneously a driving torque if fed by a power supply. It shows the experimental electromotive force (EMF) measures, both for the electrodynamic centering and for the motor functions, obtained on a prototype, operating in quasistatic conditions. It also shows the measured radial forces generated by the electrodynamic bearing and the measured drive torque in these conditions. These measures show a good agreement with model predictions. These measures also confirm the theoretical conclusi...
IEEE International Conference on Sustainable Energy Technologies, 2010
A compact flywheel energy storage system assisted by axial-flux partially-self-bearing permanent magnet motor has been proposed by the authors. The proposed machine combines axial magnetic bearing and motoring functionality into a single magnetic actuator, which not only spins the rotor-flywheel but also generates a levitation force to overcome the gravity. The mathematical model of the levitation force and stiffness of
In this paper the principles of motor torque and suspension force generation in bearingless brushless motors with high pole numbers are explained, graphically illustrated and analyzed in detail. The necessary harmonic components of the flux density in the air-gap are calculated and it is visualized how these can be generated by superposition of harmonics depending on a specific rotor pole / stator slot ratio. Especially, for bearingless motors with a fractional pole / slot ratio, it is shown how superior suspension performance and high rotational speeds can be achieved. The considerations are exemplified for a 26-pole / 24-slots bearingless brushless motor.
Magnetic Bearing with Uniaxial Control Using Magnetic, Electrodynamic and Electromagnetic Levitation
2014
Magnetic bearings use magnetic force to sustain loads without any contact between the rotor and the bearing, therewith there is no friction or wear. Due to these advantages, these bearings are applied in wide range of applications, from flywheel energy storage systems to artificial hearts. In the first, the magnetic bearing reduces energy loss by friction, raising the performance, and in the second, the magnetic bearing minimizes the damage to blood cells. Many types of magnetic bearings are known, each one based on different levitation techniques, e.g. based on the use of superconductive materials. However, the superconductivity is obtained only at temperatures around 100 K, imposing limitations for practical applications at room temperature. A more promising technique is the electrodynamic levitation at room temperature. The repulsion force for the levitation is generated by the relative movement between a magnetic field and a conductor. The inconvenient of this technique is that ...