CN100381720C - Design method for permanent magnet bias inner rotor radial mixed magnetic bearing - Google Patents

Abstract

The design method of mixed magnetic bearing with permanent magnetic bias inner rotor has the displacement rigidity of the magnetic bearing as main consideration, and the maximum bearing capacity, saturation magnetic induction and tankful rate as restraint conditions. Compared with available design method with optimal work point of the permanent magnet as target, the method of the present invention has the advantages of easy control of magnetic bearing, reasonable permanent magnet size, high accuracy, and being simple and practical. The design philosophy of the present invention may be used in design of different kinds of mixed magnetic bearing with permanent magnetic bias inner rotor.

Description

A kind of design method of permanent magnet bias inner rotor radial mixed magnetic bearing

Technical field

The present invention relates to a kind of design method of non-contact magnetically suspension bearing, particularly a kind of magnetically levitated flywheel, magnetic suspension control torque gyroscope etc. need the design method of the device of magnetic suspension bearing with permanent magnet bias inner rotor radial mixed magnetic bearing, and its design philosophy can be used as the design of all kinds of permanent magnet bias inner rotor radial mixed magnetic bearings.

Background technique

Magnetic suspension bearing divides pure electromagnetic type and permanent magnet bias to power up the hybrid magnetic suspension bearing of magnetic control system, the former uses, and electric current is big, power consumption is big, permanent magnet bias powers up the hybrid magnetic suspension bearing of magnetic control system, main bearing capacity is born in the magnetic field that permanent magnet produces, electromagnetism magnetic field provides auxiliary adjusting bearing capacity, thereby this bearing can reduce to control electric current greatly, reduces the wastage.What magnetic bearings control mode commonly used adopted is traditional pid control mode, realize that the controller parameter of this kind mode determined by bearing rigidity and damping, through facts have proved in a large number, for making magnetic bearing have excellent characteristic, should make bearing rigidity and its displacement rigidity on the same order of magnitude, so the displacement rigidity of magnetic bearing is most important for the control of magnetic bearing.Existing magnetic bearing design method all utilizes the permanent magnet best operating point to design, purpose is to make permanent magnet volume minimum, but the magnet size that calculates by this method will be very little, it is very difficult to add trade union, and this kind method do not consider the influence of displacement rigidity to control system, thereby the existing design method defective that has poor accuracy and be unfavorable for controlling.Here need to prove that the internal rotor magnetic bearing is different with external rotor magnetic bearing mentality of designing, for inner rotor core, its thinking is to design the magnetic bearing rotor assembly earlier, designs stator module (comprising permanent magnet) then; For the external rotor magnetic bearing, design the magnetic bearing stator module earlier, design magnetic bearing rotor assembly (comprising permanent magnet) again, and the inner rotor radial mixed magnetic bearing of different structure and external rotor magnetic bearing, its magnetic structure is diverse, thereby can not simply the design method cover of external rotor magnetic bearing be used for the design of internal rotor magnetic bearing.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, a kind of design method of permanent magnet bias inner rotor radial mixed magnetic bearing is provided.

Technical solution of the present invention is: a kind of design method of permanent magnet bias inner rotor radial mixed magnetic bearing needs to determine: stator core radial outside height D _S1, frame bore D _S2, stator slot radial outside height H, stator core width b _s, the stator core axial length L _Sfe, the rotor core outer diameter D _R1, the rotor core axial length L _Rfe, the permanent magnet outer diameter D _Pm1(be the rotor core inside diameter D _R2), permanent magnet axial length h _Pm, width of rebate L _cAnd turn number N.

Its characteristics are: this method is based on the displacement rigidity of magnetic bearing, and its concrete steps are as follows:

(1) sets rotor speed n and maximum load capacity F according to the index request of the device of required magnetic suspension bearing _Max, require to set the static suspension current i according to power consumption, according to existing level of processing setting gap length δ and lamination COEFFICIENT K _Fe, set the displacement rigidity K of magnetic bearing according to the requirement of existing magnetic bearing controller _x, set leakage coefficient σ, set saturation magnetic induction B unshakable in one's determination according to magnetic field analysis according to the magnetization characteristic of selected core material _s

(2) determine the permanent magnet inside diameter D according to the intensity of rotor speed and material _Pm2

(3) according to maximum load capacity F _Max, saturation magnetic induction B _sAnd lamination COEFFICIENT K _FeDetermine stator core sectional area A;

(4) require to determine stator core width b according to reality _sWith the stator core axial length L _SfeProportionate relationship, and then definite stator core width b _s, the stator core axial length L _SfeAnd rotor core axial length L _Ref

(5) by the magnetic circuit analysis, reasonable distribution stator and rotor each several part magnetic unshakable in one's determination is close, calculates rotor core yoke portion thickness h _Rfe

(6) according to the magnetic air gap length δ between the rotor, determine permanent magnet axial length h _PmAnd width of rebate L _c

(7) according to displacement rigidity K _xCalculate the permanent magnet outer diameter D _Pm1(be the rotor core inside diameter D _R2), determine current stiffness K in conjunction with rotor gravity G again _i, determine the diameter d of winding wire by current density, J and static suspension current i _c

(8) according to rotor core yoke portion thickness h _RfeDetermine the rotor core outer diameter D _R1, determine frame bore D by gap length δ _R2

(9) require to determine stator slot radial outside height H according to copper factor, and then definite stator core radial outside height D _S1

(10) according to current stiffness K _iDetermine turn number N.

Described displacement rigidity span determines by controller, be taken as-0.5N/um～-3N/um; Described gap length δ is taken as 0.15～0.35mm; Described leakage coefficient σ is taken as 1.1～3; Described lamination COEFFICIENT K _FeBe that ratio by actual stator or rotor core weight and its calculated value obtains, be taken as 0.75～0.95; Described stator core width b _sWith the stator core axial length L _SfeProportionate relationship require to determine that by reality if magnetic bearing requires axial length short, then this ratio value is taken as 4～6, otherwise this ratio value is taken as 1～3; Described copper factor is taken as 40%～60%.

Principle of the present invention is: the present invention starts with the displacement rigidity of radial hybrid magnetic bearing and designs, and sets each parameter as requested, by the magnetic circuit analysis and the calculating of this kind magnetic bearing, can obtain other physical dimension of magnetic bearing.Can obtain the permanent magnet inside diameter D according to the rotor speed n that sets and the requirement of strength of material _Pm2, according to maximum load capacity F _Max, saturation magnetic induction B _sAnd lamination COEFFICIENT K _FeDetermine stator core sectional area A by following formula.

$A=\frac{F_{\max }\&CenterDot;{\mathrm{\&mu;}}_0}{{\mathrm{<figure-callout\; id="2"\; label="B\; s"\; filenames="C20061011426900091.png"\; state="\{\{state\}\}">B</figure-callout>}}_s^{}\&CenterDot;K_{\mathrm{fe}}}---\left(1\right)$

μ in the formula ₀=4 π * 10 ^-7H/m is the permeability of air.

Set sub width b unshakable in one's determination _sWith the stator core axial length L _SfeRatio be C, stator core width b then _sWith the stator core axial length L _SfeFor:

$L_{\mathrm{sfe}}=\sqrt{\frac{A}{C}}---\left(2\right)$

b _s＝C·L _sfe (3)

For fear of because stator and rotor axis unshakable in one's determination misaligns the magnetic pull that causes, desirable rotor core axial length L _RfeFor:

L _rfe＝1.15·L _sfe?(4)

According to the magnetic circuit analysis, reasonable distribution stator and rotor each several part magnetic unshakable in one's determination is close, calculates rotor core yoke portion thickness h _RfeFor:

$h_{\mathrm{rfe}}=\frac{\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="C20061011426900091.png"\; state="\{\{state\}\}">A</figure-callout>}}{2\&CenterDot;L_{\mathrm{rfe}}}/3---\left(5\right)$

Coefficient 3 is to consider stator core yoke portion mainly by electro-magnetic flux in the formula, and by permanent magnet flux, when magnetic bearing bore maximum load capacity, electro-magnetic flux was not generally 1/3 of permanent magnet flux.

Magnetic air gap length δ according between the rotor of setting can obtain permanent magnet axial length h _PmAnd width of rebate L _cFor:

h _pm＝K ₁·δ (6)

L _c＝K ₂·h _pm (7)

K in the formula ₁, K ₂Be constant, rule of thumb value.

According to displacement rigidity K _xCan obtain the permanent magnet outer diameter D _Pm1(be frame bore D _R2) be:

$D_{\mathrm{pm}1}=\sqrt{\frac{4h_{\mathrm{pm}}}{C_1\&CenterDot;{\mathrm{\&mu;}}_{\mathrm{pm}}\&CenterDot;{\mathrm{\&mu;}}_0\&CenterDot;\mathrm{\&pi;}}+{\mathrm{<figure-callout\; id="2"\; label="D\; pm"\; filenames="C20061011426900091.png"\; state="\{\{state\}\}">D</figure-callout>}}_{\mathrm{pm}}^2}---\left(8\right)$

In the formula: $C_1=\frac{\sqrt{-\frac{{\mathrm{<figure-callout\; id="2"\; label="F\; pm"\; filenames="C20061011426900091.png"\; state="\{\{state\}\}">F</figure-callout>}}_{\mathrm{pm}}^{}\&CenterDot;{\mathrm{\&mu;}}_0\&CenterDot;A}{K_x\&CenterDot;{\mathrm{\&sigma;}}^2\&CenterDot;\mathrm{\&delta;}}}-\mathrm{\&delta;}}{2\&CenterDot;{\mathrm{\&mu;}}_0\&CenterDot;A}---\left(9\right)$

F wherein _Pm=H _PmH _PmBe the magnetomotive force of permanent magnet, H _PmCoercivity for permanent magnet is generally 760kA/m～790kA/m; μ _PmBe the relative permeability of permanent magnet, generally be taken as 1.03～1.05.

Can get current stiffness K in conjunction with rotor gravity G _i:

$K_i=\frac{G/2-K_x\&CenterDot;x}{i}---\left(10\right)$

Rotor center was apart from the side-play amount of magnetic center when x was static suspension in the formula.

Determine the diameter d of winding wire by current density, J and static suspension current i _cFor:

$d_c=\sqrt{\frac{4\&CenterDot;i}{\mathrm{\&pi;}\&CenterDot;J}}---\left(11\right)$

Then according to the NBS value.

Require to determine stator slot radial outside height H according to copper factor, and then definite stator core radial outside height D _S1For:

D _s1＝D _st+2·L _sfe (12)

According to current stiffness K _iCan be in the hope of turn number N:

$N=\frac{K_k\&CenterDot;R_{\mathrm{pmsum}}\&CenterDot;\mathrm{\&sigma;}\&CenterDot;{\mathrm{\&delta;}}^2}{2\&CenterDot;F_{\mathrm{pm}}\&CenterDot;(R_{\mathrm{pmsum}}-R_{\mathrm{pm}})\&CenterDot;{\mathrm{\&mu;}}_0\&CenterDot;A}---\left(13\right)$

In the formula: R _PmBe permanent magnet magnetic resistance, R _PmsumBe the total magnetic resistance of permanent magnetic circuit.

So far, whole permanent magnet bias inner rotor radial mixed magnetic bearing design finishes.

The present invention's advantage compared with prior art is: the present invention is because employing is the design method of starting point with the radial hybrid magnetic bearing displacement rigidity, is that the design method of starting point is compared with existing inner rotor radial mixed magnetic bearing with the permanent magnet best operating point, be beneficial to control more, the parameter that obtains is more reasonable.

Description of drawings

Fig. 1 is the structural drawing of the permanent magnet bias inner rotor radial mixed magnetic bearing that the present invention is directed to;

Fig. 2 is a design flow diagram of the present invention;

The permanent magnet bias inner rotor radial mixed magnetic bearing pictorial diagram of Fig. 3 for designing according to the present invention, wherein (a) is the stator module of inner rotor radial magnetic bearing, (b) is the rotor assembly of inner rotor radial magnetic bearing.

Embodiment

As shown in Figure 1, design object of the present invention is a kind of magnetic suspension control torque gyroscope permanent magnet bias inner rotor radial mixed magnetic bearing, and 1 is magnetic guiding loop among the figure, 2 is permanent magnet, and 3 are rotor core, and 4 is the magnetic air gap between the rotor, 5 is coil, and 6 are stator core.Set the displacement rigidity K of magnetic bearing according to the requirement of existing magnetic bearing controller _xFor-0.8N/um, set rotor speed n according to the magnetic suspension control torque gyroscope index request and be taken as 30000r/min, set the permanent magnet inside diameter D by the strength of materials again _Pm2Be 19mm, set gap length δ according to existing level of processing and be taken as 0.2mm, the lamination COEFFICIENT K _FeBe 0.85, setting leakage coefficient σ according to the magnetic field analysis of this magnetic bearing is 1.2, sets maximum load capacity F according to the index request of magnetic suspension control torque gyroscope _MaxBe 108.7N, requiring to set the static suspension current i according to the power consumption of magnetic suspension control torque gyroscope is 0.2A, and the stator and rotor iron core of magnetic bearing is selected the thick 1J50 of iron nickel magnetically soft alloy 0.1mm for use among this embodiment, sends out saturation magnetic induction B fixed according to the magnetization curve of 1J50 _sBe 1.2T.The level set stator copper factor that rolls off the production line according to existing coil is 40%.

According to above condition, can calculate stator core sectional area A=111.6mm by (1) formula ², set sub width b unshakable in one's determination _sWith the stator core axial length L _SfeRatio C=2.5, then can draw stator core width b by formula (2) and (3) _s=15mm, the stator core axial length L _Sfe=6mm can get the rotor core axial length L by formula (4) _Rfe=7mm can get rotor core yoke portion thickness h by formula (5) _Rfe=2.7mm, make K ₁=24, K ₂=2, can obtain permanent magnet axial length h by formula (6) and (7) _Pm=4.8mm, width of rebate L _c=9.6mm can get the permanent magnet outer diameter D by formula (8) and (9) _Pm1=28.2mm considers that rotor center can get current stiffness K apart from the side-play amount x=0.1mm of magnetic center by (10) behind the general magnetic bearing static suspension _i=119.8N/A can be got the diameter d of winding wire by formula (11) _c=0.356mm is taken as 0.35mm, can get stator slot radial outside height H=52mm according to the copper factor of setting after by program cycle, can get stator core radial outside height D by formula (12) _S1=64mm can get turn number N=87 circles by formula (13).So far, this permanent magnet bias inner rotor radial mixed magnetic bearing design finishes.

The content that is not described in detail in the specification of the present invention belongs to related domain professional and technical personnel's known prior art.

Claims (7)

1. the design method of a permanent magnet bias inner rotor radial mixed magnetic bearing, it is characterized in that: this method is based on the displacement rigidity of magnetic bearing, and its concrete steps are as follows:

(1) the displacement rigidity K of setting magnetic bearing _x, rotor speed n, gap length δ, leakage coefficient σ, lamination COEFFICIENT K _Fe, maximum load capacity F _Max, static suspension current i and saturation magnetic induction B unshakable in one's determination _s

(2) determine the permanent magnet inside diameter D according to the intensity of rotor speed n and material _Pm2

(3) according to maximum load capacity F _Max, saturation magnetic induction B _sAnd lamination COEFFICIENT K _FeDetermine stator core sectional area A;

(4) require to determine stator core width b according to reality _sWith the stator core axial length L _SfeProportionate relationship, and then definite stator core width b _s, the stator core axial length L _SfeAnd rotor core axial length L _Rfe

(5) by the magnetic circuit analysis, distribute stator and rotor each several part magnetic unshakable in one's determination close, calculate rotor core yoke portion thickness h _Rfe

(6) according to the magnetic air gap length δ between the rotor, determine permanent magnet axial length h _PmAnd width of rebate L _c

(7) according to displacement rigidity K _xCalculate the permanent magnet outer diameter D _Pm1, determine current stiffness K in conjunction with rotor gravity G again _i, determine the diameter d of winding wire by current density, J and static suspension current i _c

(8) according to rotor core yoke portion thickness h _RfeDetermine the rotor core outer diameter D _R1, determine frame bore D by gap length δ _S2

(9) require to determine stator slot radial outside height H according to copper factor, and then definite stator core radial outside height D _S1

(10) according to current stiffness K _iDetermine turn number N.

2. the design method of a kind of permanent magnet bias inner rotor radial mixed magnetic bearing according to claim 1 is characterized in that: described displacement rigidity span determines by controller, be taken as-0.5N/um～-3N/um.

3. the design method of a kind of permanent magnet bias inner rotor radial mixed magnetic bearing according to claim 1, it is characterized in that: described gap length δ is taken as 0.15～0.35mm.

4. the design method of a kind of permanent magnet bias inner rotor radial mixed magnetic bearing according to claim 1, it is characterized in that: described leakage coefficient σ is taken as 1.1～3.

5. the design method of a kind of permanent magnet bias inner rotor radial mixed magnetic bearing according to claim 1 is characterized in that: described lamination COEFFICIENT K _FeBe that ratio by actual stator or rotor core weight and its calculated value obtains, be taken as 0.75～0.95.

6. the design method of a kind of permanent magnet bias inner rotor radial mixed magnetic bearing according to claim 1 is characterized in that: described stator core width b _sWith the stator core axial length L _SfeProportionate relationship require to determine that by reality if magnetic bearing requires axial length short, then this ratio value is taken as 4～6, otherwise this ratio value is taken as 1～3.

7. the design method of a kind of permanent magnet bias inner rotor radial mixed magnetic bearing according to claim 1, it is characterized in that: described copper factor is taken as 40%～60%.

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