CN101170270A - Magnetic bearing planar permanent magnet synchronous motor - Google Patents

Abstract

A magnetic suspension bearing planar permanent magnet synchronous motor belongs to the magnetic suspension bearing permanent magnet synchronous motor. The motor comprises a rotor (2), motor stators (3, 6), a magnetic suspension bearing stator (1), a sensor (5) and a sensor bracket (4). The two motor stators are respectively located on both axial sides of the rotor, the magnetic suspension bearing stator is located on the radial outer side of the rotor, and the levitation force magnetic field generated is distributed in the radial plane of the rotor; the sensor bracket is located on the radial inner side of the rotor. The 8-pole symmetrical structure of the radial magnetic suspension bearing is adopted, and the suspension force in the two radial directions is independently controlled to realize the radial suspension of the motor. The rotor of the motor adopts a thin sheet structure, which controls the suspension of two degrees of freedom in the radial direction of the motor to realize the stable suspension of five degrees of freedom in the rotor space, simplifies the control system of the magnetic levitation structure, and reduces the volume of the motor; it has a simple control mechanism and low power consumption , no friction and other unique advantages, it has broad application prospects in aerospace, small rotating high-speed machinery, energy life science and other fields.

Description

Magnetic bearing planar permanent magnet synchronous motor

technical field

The invention belongs to a motor, in particular to a magnetic suspension bearing plane permanent magnet synchronous motor.

Background technique

The so-called planar permanent magnet synchronous motor is a motor in which the stator is located on both sides of the rotor in the axial direction, and the air gap magnetic field is distributed in a plane along the axial direction. In 1821, Faraday invented the world's first motor, the planar permanent magnet synchronous motor. Limited to the material and technology level at that time, the planar permanent magnet synchronous motor could not be further developed. However, people gradually realized some weaknesses of ordinary cylindrical motors, such as difficulty in cooling and low utilization of the rotor core. Since the 1940s, the planar permanent magnet synchronous motor has received the attention of the motor industry again. At present, many planar permanent magnet synchronous motors of different types and structures have been developed abroad.

Active magnetic suspension bearing is a new type of high-performance bearing that uses magnetic force to suspend the rotor in space, so that there is no mechanical friction support between the rotor and the stator. Magnetic bearings have unique advantages - no contact, no lubrication, no wear, long life, online adjustable stiffness and damping, and can adapt to various operating conditions, so they are becoming more and more attractive in the field of support. It is used in high-speed machine tools , steam turbine engine, air compressor, vacuum molecular pump, shock absorber, energy storage flywheel, multi-dimensional platform, rate gyroscope and satellite antenna positioning and other fields have been increasingly widely used.

If the magnetic suspension bearing is combined with the planar permanent magnet synchronous motor, it will bring a series of advantages.

Contents of the invention

The object of the present invention is to provide a magnetic bearing planar permanent magnet synchronous motor with small volume, simple structure, low cost and meeting the requirements of no contact, no wear, no pollution and high efficiency.

The object of the present invention can be achieved through the following measures:

First of all, the motor rotor of the present invention adopts a radially layered structure, the inner layer is a magnetically conductive layer, and the motor torque magnetic field passes through it; the outer layer is also a magnetically conductive layer, through which the radial levitation force magnetic field passes; the middle layer is a magnetically isolated layer, Used to separate two magnetic fields so that they do not couple with each other.

Secondly, the motor stator of the present invention adopts six salient poles, on which coils are wound and a three-phase current is passed through, so as to generate a four-pole rotating magnetic field in the air gap.

Third, the magnetic bearing part of the present invention adopts the 8-pole symmetrical structure of the common radial magnetic suspension bearing, its magnetic field is distributed in the radial plane, and the control of the levitation force in the X direction and the Y direction is independent.

The motor includes a magnetic suspension bearing, a motor rotor, a motor stator, a sensor, and a sensor bracket, and is characterized in that the magnetic suspension bearing is an 8-pole symmetrical structure of a radial magnetic suspension bearing, and is located on the radially outer side of the motor rotor; the motor rotor is The sheet structure whose radial diameter is greater than the axial length is composed of an outer magnetic layer, an inner magnetic layer, and a set of magnetic isolation layers sandwiched between the inner and outer magnetic layers. The upper and lower surfaces of the motor rotor are pasted with permanent magnets. patch; the motor stator refers to the upper stator of the motor and the lower stator of the motor. The excitation winding; the sensor is installed on the sensor bracket, and is located on the radial inner side of the motor rotor through the sensor bracket.

In order to simplify the structure, the rotor of the motor adopts a sheet-like structure (that is, the radial dimension of the rotor is much larger than the axial dimension), as long as the suspension of the two degrees of freedom in the radial direction is actively controlled, and the passive direction is realized in the axial and torsional directions. Suspension, so as to realize the stable suspension of five degrees of freedom in the rotor space, remove the axial magnetic bearing, greatly reduce the volume of the motor, and greatly simplify the control system of the motor. Therefore, the magnetic bearing planar permanent magnet synchronous motor of the present invention has the following advantages:

1. Small size, simple structure, novel and reasonable design, simple control system, and can work in a magnetic levitation state without contact, pollution, and friction.

2. Durable and reliable, it can run for a long time without maintenance, and without replacing parts. Especially for some medical instruments and instruments that need to work continuously, the application advantages are particularly prominent.

Description of drawings

Fig. 1 is a structural diagram of the present invention;

In Figure 1: 1 magnetic suspension bearing, 2 motor rotor, 3 motor upper stator, 4 sensor bracket, 5 sensor, 6 motor lower stator;

Fig. 2 is the expanded view of motor structure of the present invention;

Fig. 3 is a structural diagram of a magnetic bearing of the present invention;

Fig. 4 is the rotor structural diagram of the present invention;

In Figure 4: 7 outer magnetic layers, 8 middle magnetic isolation layers, 9 permanent magnetic patches, 10 inner magnetic layers;

Fig. 5 is a schematic diagram of the direction of the radial levitation magnetic circuit of the present invention;

Fig. 6 is the schematic diagram of the passive suspension of the rotor of the present invention; wherein figure (a) is a schematic diagram of returning to its original position when the rotor is offset in the axial direction by a magnetic pull in the opposite direction; figure (b) is a schematic diagram of when the rotor When there is a deviation in the twisting direction, it is subjected to a magnetic pull in the opposite direction and returns to its original position.

Detailed ways

As shown in accompanying drawing 1, the main composition of the magnetic bearing planar permanent magnet synchronous motor of the present invention is: a laminar rotor, two motor stators, a magnetic suspension bearing stator and a sensor support (place four displacement sensors above).

Accompanying drawing 2 has set forth the motor structure of the magnetic bearing planar permanent magnet synchronous motor of the present invention and its magnetic circuit trend, it can be seen that it has two motor stators, which are symmetrically distributed on both sides of the rotor, so the air formed between them The gap is planar, and the direction of the magnetic field is axial. The upper and lower surfaces of the rotor of the present invention respectively have four planar permanent magnet patches, two N poles and two S poles are arranged at intervals, while the stator has six salient poles, on which coils are wound and connected to three-phase The current generates a quadrupole rotating magnetic field in the air gap. Both the magnetic field generated by the permanent magnet patch on the surface of the rotor and the magnetic field generated by the stator winding in the present invention can be regarded as approximately sinusoidal distribution, and they jointly excite the magnetic force, that is, the motor torque and the axial suction force.

The magnetic field formed by the permanent magnet patch on the surface of the rotor of the present invention can be equivalently regarded as being generated by a energized coil, the number of coil turns is N _f , and the magnitude of the current is _if . And N _f , the size of _if can be obtained by the following formula:

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; P</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; P</span>}\frac{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Wherein H _m is the magnetic field size of the permanent magnet, B _m is the magnetic induction intensity size of the permanent magnet, l _m is the thickness of the permanent magnet, μ ₀ is the magnetic permeability rate in vacuum, μ _r is the relative magnetic permeability of the permanent magnet patch rate, and P is the number of pole pairs of the magnetic field.

Transform the three-phase current of the stator into the rotating coordinate system, and after calculation, the final expressions of the unilateral torque T _s and axial suction F _s can be obtained:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}{\mathrm{<span\; class="notranslate">\; 16</span>}\mathrm{<span\; class="notranslate">\; Pg</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 16</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; [</span>{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Among them, N _s is the number of turns of each phase winding in the stator, R _i and R ₀ are the inner and outer radii of the rotor, P is the number of pole pairs of the magnetic field, g is the size of the air gap of the unilateral magnetic field, and _id and i _q are straight The magnitude of axial current and quadrature axial current.

Then, the total torque and axial force can be expressed as:

T _total = T _up + T _down (4)

F _total = F _up - F _down (5)

Among them, T _{is always} the combined torque generated by the upper and lower motor stators to the rotor, T _upper is the torque generated by the upper motor stator to the rotor, T _lower is the torque generated by the lower motor stator to the rotor, and F is _always the upper and lower motors The synthetic axial suction generated by the stator on the rotor, F _above is the axial suction generated by the stator of the upper motor on the rotor, and F _below is the axial suction generated by the stator of the lower motor on the rotor.

It can be seen that by changing the direct axis current _id , the _total size of the combined axial suction force F can be changed, but the _total size of the combined torque T will not be affected. Therefore, when the radial magnetic bearing cannot generate enough axial passive levitation force, the axial active levitation can be realized by controlling the _total magnitude of the combined axial suction force F.

Accompanying drawing 3 is radial magnetic suspension bearing structural diagram of the present invention, adopts the 8-pole symmetrical structure of common radial magnetic suspension bearing, its magnetic field is distributed in radial plane, and the levitation force of X direction and Y direction The controls are independent and can finally be expressed as:

F _y =k _i ·i _x +k _y ·y (6)

Among them: _ki is the current-force coefficient, _ky is the displacement-force coefficient, _ix is the current magnitude of the magnetic suspension bearing winding, and y is the rotor displacement.

As shown in accompanying drawing 4, in order to make the motor torque magnetic field and the radial levitation force magnetic field not coupled with each other, the motor rotor of the present invention must adopt a radial layered structure: the inner layer is a magnetic conductive layer, and the motor torque magnetic field is along the axial direction The direction passes through it; the outer layer is also a magnetic permeable layer, and the radial levitation force magnetic field passes through it along the direction of the radial plane, as shown by the black line in Figure 5; the middle is a magnetic isolation layer, which is used to separate the two magnetic fields .

Accompanying drawing 6 is a schematic diagram of the principle of passive axial stabilization of the sheet-shaped rotor of the present invention. When the rotor deviates in any axial or torsional direction, it will be returned to its original position by a magnetic pull in the opposite direction.

Claims (1)

1. magnetic suspension bearing plane permanent magnetic synchronization electromotor, comprise magnetic suspension bearing (1), rotor (2), motor stator (3,6), transducer (5), sensor stand (4), it is characterized in that, described magnetic suspension bearing (1) is 8 utmost point symmetrical structures of radial magnetic bearing, is positioned at the radial outside of rotor (2); Described rotor (2) is the flake structure of radial diameter greater than axial length, be made up of every magnetosphere (8) clamping one cover between outer magnetic layer (7) and internal layer magnetic layer (10) and the inside and outside magnetic layer (7,10), the upper and lower surface of rotor (2) all is pasted with permanent magnet coating (9); Described motor stator is meant stator (6) under stator on the motor (3) and the motor, and upper and lower two motor stators (3,6) place the upper and lower both sides of rotor axial respectively, equal coiling excitation winding on the salient pole of upper and lower two motor stators (3,6); Described transducer (5) is installed on the sensor stand (4), is positioned at the radially inner side of rotor (2) by sensor stand (4).

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