Permanent-magnet bias outer rotor radial AC hybrid magnetic bearing

Abstract

The invention discloses a permanent-magnet bias outer rotor radial AC hybrid magnetic bearing. A stator core is arranged in the middle of the rotor core; the stator core is provided with 6 identical stator core magnetic poles, which are uniformly distributed in the circumferential direction and extend outwards in the radial direction; the three stator core magnetic poles, which are mutually isolated, are respectively provided with an slot; identical cuboid permanent magnets, which are used for providing static bias flux, are respectively embedded in the slots; the S pole of each permanent magnet faces the stator core, and the N pole faces the rotor core; the other 3 stator core magnetic poles, which are mutually isolated, are respectively wound by identical control coils; the top end of each stator core magnetic pole is provided with a groove; identical position sensors are arranged in the grooves; and control fluxes are formed among the stator core, radial air gap and rotor core. The invention reduces the magnetic resistance of the control magnetic circuit, lowers the coil copper loss and power amplification loss, has the advantages of small size and light weight and enhances the working efficiency of the magnetic bearing.

Description

technical field [0001] The invention relates to a non-mechanical contact magnetic bearing, in particular to a permanent magnet bias outer rotor radial AC hybrid magnetic bearing with small volume and low power consumption, which can be used as a five-degree-of-freedom magnetic levitation high-speed machine tool spindle, a bearingless motor and Non-contact suspension support for rotating parts in mechanical equipment such as flywheel energy storage systems and spacecraft such as satellites and space stations. Background technique [0002] Since the rapid development of magnetic bearing technology in the 1970s, due to the advantages of reducing control current and loss, hybrid magnetic bearings that provide static bias magnetic flux by permanent magnets and control magnetic flux by DC signals have been developed. It has become a research hotspot, but this type of magnetic bearing cannot meet the requirements of low production cost and low power consumption. On the one hand, d...

AI Technical Summary

Problems solved by technology

[0002] Since the rapid development of magnetic bearing technology in the 1970s, due to the advantages of reducing control current and loss, hybrid magnetic bearings that provide static bias magnetic flux by permanent magnets and control magnetic flux by DC signals have been developed. It has become a research hotspot, but this type of magnetic bearing cannot meet the requirements of low production cost and low power consumption

On the one hand, due to the use of DC control, the DC power amplifier is expensive and bulky, and a radial magnetic bearing usually requires four unipolar or two bipolar power amplifier circuits, which directly leads to the large size and high cost of the power amplifier. , which greatly limits the application fields of magnetic bearings, especially in aerospace and military applications

On the other hand, the permanent magnet bias external rotor radial AC hybrid magnetic bearings currently researched internationally are divided into heteropolar and homopolar structures: the magnetic force lines of the heteropolar structure magnetic bearings are perpendicular to the rotor axis, and the axial length can be made The magnetic bearings with the same polarity are shorter, but hysteresis loss will be generated; the magnetic force lines of the magnetic bearings with the same polarity structure are parallel to the rotor axis, and the generated hysteresis loss is greatly reduced, but the occupied axial space is relatively large, which cannot meet the needs of spacecraft such as satellites and space stations. The required small size and light weight are not conducive to the increase of the critical speed of the rotor

In addition, for some heteropolar magnetic bearings, the permanent magnet is directly placed in the control magnetic circuit, and the control magnetic flux must pass through the permanent magnet. Since the permanent magnet has a large reluctance, it is necessary to increase the control coil to generate the corresponding control magnetic flux. The excitation current increases the power consumption of the magnetic bearing, causing serious heating of the coil; some magnetic bearings with the same polarity structure directly connect the permanent magnet to the stator laminated core, so that the permanent magnetic circuit will lose too much when passing through the stator core The magnetomotive force greatly weakens the bearing capacity of the magnetic bearing

[0003] At the Seventh International Magnetic Bearing Conference in 2000, Redemann C of the Swiss Federal Institute of Technology (ETH) in Zurich published a test report on the application of a 30kW bearingless sealed pump, and studied a two-degree-of-freedom three-phase AC hybrid magnetic bearing. The bearing directly uses the three-phase inverter commonly used in the industry to provide the control current, and uses the permanent magnet to provide the static bias magnetic field, which greatly reduces the size of its power amplifier and reduces the loss, but it still fails to achieve compactness in the overall system structure. Progress has been made in increasing the critical speed of the rotor and increasing the capacity of the magnetic bearing

[0004] The existing relevant patent applications are as follows: (1) The patent number is 200510040267.4, and the name is "Permanent Magnet Bias Radial Magnetic Bearing". The windings on the two opposite teeth are connected in series, and the DC drive is adopted. The magnetic bearing of this structure has high power consumption and the cost of the power amplifier is relatively high.

(2) Patent No. 200510086223.5, titled "A Permanent Magnet Bias Outer Rotor Radial Magnetic Bearing" uses a single-piece 8-pole heteropolar magnetic bearing structure to control 2 degrees of freedom in the radial direction, and 4 parallel magnetization The permanent magnet is embedded in the stator core, and a DC power amplifier is used to drive and control four radial control coils. The magnetic bearing of this structure is relatively small in size, but has high power consumption

(3) Patent No. 200510011270.3, titled "A Low Power Consumption Permanent Magnet Bias Outer Rotor Radial Magnetic Bearing" In form, it adopts a double-plate eight-pole homopolar magnetic bearing structure to control two degrees of freedom in the radial direction. And it uses a DC power amplifier to drive and control 8 radial control coils. The magnetic bearing of this structure has a large volume and higher power consumption than the AC-driven magnetic bearing.

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