Summary of the invention
2 subharmonic and the poor defect of high order harmonic component effect is suppressed for existing magnetic suspension permanent magnet planar motor stator permanent magnet array, a kind of method of magnetic suspension permanent magnet planar motor magnetic steel array parameter optimization is proposed, make magnetic suspension permanent magnet planar motor restrained effectively high order harmonic component, especially have stronger inhibitory action to 2 subharmonic.
For achieving the above object, the technical solution adopted in the present invention is: the stator of magnetic suspension permanent magnet planar motor is permanent magnetic steel array, adopts Halbach arrangement mode to combine, comprise the following steps by main magnet steel and secondary magnet steel;
(1) Halbach type magnetic steel array magnetic system of coordinates is set up
with
, coordinate system
initial point be positioned at main magnet steel center,
axle,
axle is vertical with main magnet steel limit respectively, coordinate system
for coordinate system
around
axle is rotated counterclockwise
the coordinate system of rear gained,
place is strong side, magnetic field;
Utilize magnetic field, Halbach magnetic steel array strong side at coordinate system
under the close harmonic-model of magnetic
, obtain magnetic field, Halbach magnetic steel array strong side at coordinate system
under the close vector of magnetic
, calculate the average fundamental voltage amplitude on the differentiated levels of distance magnetic steel array surface
, by average fundamental voltage amplitude
build magnetic close expectation first-harmonic model
;
(2) according to the described average fundamental voltage amplitude on differentiated levels
calculate at effective magnetic field spatial altitude
the close overall average fundamental voltage amplitude of expectation magnetic in scope
;
(3) according to the close harmonic-model of described magnetic
try to achieve the close i.e. close vector of magnetic of actual magnetic of magnetic steel array
's
,
with
axial component
, according to described magnetic close expectation first-harmonic model
try to achieve and expect that magnetic is close namely
's
,
,
axial component
, thus try to achieve the close average relative mean square deviation close with expectation magnetic of actual magnetic
;
(4) by close for described expectation magnetic overall average fundamental voltage amplitude
, described actual magnetic close with expect the close average relative mean square deviation of magnetic
discretization, makes the close overall average fundamental voltage amplitude of described expectation magnetic
with ratio
relation curve and described average relative mean square deviation
with
relation curve, according to the close overall average fundamental voltage amplitude of described expectation magnetic
should large as far as possible and described average relative mean square deviation
principle that should be little as far as possible determines main magnet steel width
with secondary magnet steel width
,
for total magnet steel width.
Compared with prior art, the invention has the beneficial effects as follows:
(1) because different magnet steel parameter coordination is comparatively large on the impact of the close distribution of magnetic around magnet steel, optimum results of the present invention can restrained effectively high order harmonic component, especially has stronger inhibitory action to 2 subharmonic.
(2) Cost optimization is low, does not need other auxiliary equipment.
(3) complexity and the accuracy of algorithm has been taken into account, rationally reliably.
Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.
Embodiment
The present invention adopts average fundamental voltage amplitude to set expectation air gap flux density, sets up the Mathematical Modeling expecting air gap flux density; Utilizing the close overall average fundamental voltage amplitude of expectation magnetic within the scope of the average fundamental voltage amplitude calculating effective magnetic field spatial altitude on differentiated levels, calculating the close average relative mean square deviation with expecting air gap flux density of actual magnetic by air gap flux density harmonic-model; According to the principle determination magnet steel parameter of " expect that the close overall average fundamental voltage amplitude of magnetic should be large as far as possible, the close average relative mean square deviation close with expecting magnetic of actual magnetic should be little as far as possible ".Specific as follows:
As depicted in figs. 1 and 2, the stator of magnetic suspension permanent magnet planar motor is permanent magnetic steel array, this stator permanent magnet array adopts Halbach arrangement mode to combine by main magnet steel and secondary magnet steel, is the Halbach magnetic steel array being arranged as one-sided strengthening form by the magnet steel that two kinds of volumes are different.Large magnet steel is main magnet steel, and main magnet steel cross section is in square, and little magnet steel is secondary magnet steel, and secondary magnet steel cross section is rectangle, and the length of secondary magnet steel is equal with the cross section length of side of main magnet steel, and two kinds of magnet thicknesses are identical; Main magnet steel is identical with the secondary magnet steel magnetization, alignment and the direction of magnetization is orthogonal, and the non-magnet material that gap magnetic permeability is identical with air is filled.The close side of magnetic field magnetic of such formation is very strong, and opposite side is then more weak.Only utilize the side that the close distribution of magnetic is strong during application, magnet steel parameter coordination is very large to the close distribution influence of the magnetic around magnet steel, can be optimized according to the harmonic-model that magnetic is close to it.
Set up Halbach type magnetic steel array magnetic system of coordinates
with
, coordinate system
initial point be positioned at main magnet steel center, its
axle,
axle is vertical with main magnet steel limit respectively, coordinate system
for coordinate system
around
axle is rotated counterclockwise
the coordinate system of rear gained;
place is strong side, magnetic field.From coordinate system
to coordinate system
transformation matrix of coordinates be:
, (1)
Its inverse matrix is:
, (2)
In formula:
.
Permanent magnetic steel presses the uniform magnetization of prescribed direction shown in Fig. 1, and magnetic steel array infinitely extends in horizontal plane, disregards edge effect, and magnet steel overall width is
, main magnet steel width is
, secondary magnet steel width is
, magnet thickness is
, pole span
, magnetic field, Halbach magnetic steel array strong side is at coordinate system
the close harmonic-model of lower magnetic be:
, (3)
Wherein,
for at coordinate system
the close harmonic-model of magnetic in magnetic field, middle Halbach magnetic steel array strong side,
,
,
for at coordinate system
the coordinate figure of the close calculation level of middle magnetic,
for the relative permeability of magnet steel,
for the remanent magnetism of magnet steel,
,
be
,
harmonic order axially,
, (4)
, (5)
, (6)
, (7)
, (8)
, (9)
By close for magnetic calculation level at coordinate system
in coordinate figure adopt coordinate transform obtain at coordinate system
in coordinate figure, and being substituted into formula (3), to calculate this magnetic close
axle,
axle and
axial component, then press close for the magnetic of this point
axle,
axle and
axle decompose can this magnetic close
,
with
axial component, can obtain magnetic field, Halbach magnetic steel array strong side at coordinate system
the close harmonic-model of lower magnetic, computing formula is as follows:
, (10)
Wherein,
for at coordinate system
the close vector of magnetic in magnetic field, middle Halbach magnetic steel array strong side,
with
be respectively the close vector of magnetic
's
,
with
axial component,
,
,
for at coordinate system
the coordinate figure of the close calculation level of middle magnetic.
Based on the close harmonic-model of above-mentioned magnetic
, the present invention first utilizes the close harmonic-model of magnetic
calculate the average fundamental voltage amplitude on the differentiated levels of distance magnetic steel array surface, and build the close expectation first-harmonic model of magnetic thus.Definition
, when
during for certain value, the fundamental voltage amplitude of the close each axial component of magnetic is only
(
) function.Discussion territory is set to
with
,
be effective magnetic field spatial altitude, exceed
magnetic field highly then very weak can not work is considered.When
during for certain value, the average fundamental voltage amplitude that magnetic steel array produces magnetic field is
, and have:
(11)
In formula,
with
be respectively
one timing
,
with
the average amplitude of the close component first-harmonic of axial magnetic,
with
be respectively
certain but
(
) asynchronous
,
with
the close component fundamental voltage amplitude of axial magnetic.
By the average fundamental voltage amplitude in magnetic field
building magnetic close expectation first-harmonic model is
, can obtain:
(12)
Wherein,
with
be respectively and expect the close vector of magnetic
's
,
with
axial component.
The present invention calculates the close overall average fundamental voltage amplitude of expectation magnetic within the scope of effective magnetic field spatial altitude again according to the average fundamental voltage amplitude on differentiated levels.If the close overall average fundamental voltage amplitude of the expectation magnetic in room for discussion is
, can obtain:
(13)
Wherein,
with
respectively
,
with
axially expect the close overall average fundamental voltage amplitude of magnetic.
The close actual magnetic for magnetic steel array of magnetic that then the present invention tries to achieve with the harmonic-model that magnetic is close is close, i.e. the close vector of magnetic
's
,
with
axial component
, the magnetic of trying to achieve with the expectation first-harmonic model that magnetic is close is close for expecting that magnetic is close namely
's
,
,
axial component
, try to achieve the close average relative mean square deviation close with expectation magnetic of actual magnetic further.If the close average relative mean square deviation close with expecting magnetic of actual magnetic is in room for discussion
, can obtain:
(14)
Wherein,
respectively
,
with
the average relative mean square deviation of axle,
be respectively the close vector of magnetic
's
,
with
axial component,
be respectively and expect the close vector of magnetic
's
,
with
axial component,
be respectively
one timing
,
with
the average amplitude of the close component first-harmonic of axial magnetic.
Finally, formula (13) is expected the close overall average fundamental voltage amplitude of magnetic by the present invention
and the close average relative mean square deviation close with expectation magnetic of formula (14) actual magnetic
discretization is to adopt numerical method to calculate respectively, according to the principle determination magnet steel parameter of " expect that the close overall average fundamental voltage amplitude of magnetic should be large as far as possible, the close average relative mean square deviation close with expecting magnetic of actual magnetic should be little as far as possible ".
Territory will be discussed
with
press
,
with
axially be divided into respectively
,
with
equal portions, can obtain formula (13), (14) discretization respectively:
(15)
(16)
The ratio defining secondary magnet steel width and main magnet steel width is
, make and expect the close average fundamental voltage amplitude of magnetic
with
relation curve and average relative mean square deviation
with
relation curve, according to the optimization major-minor magnet steel width parameter of " expect that magnetic close overall average fundamental voltage amplitude should be large as far as possible, the close average relative mean square deviation close with expecting magnetic of actual magnetic should be little as far as possible ", thus determine main magnet steel width
with secondary magnet steel width
.
With a specific design case, the invention will be further described below:
When
time, made by formula (15), (16) and expect the close average fundamental voltage amplitude of magnetic
with
relation curve and average relative mean square deviation
with
relation curve, as shown in Figures 2 and 3.According to the principle determination magnet steel parameter of " expect that the close overall average fundamental voltage amplitude of magnetic should be large as far as possible, the close average relative mean square deviation close with expecting magnetic of actual magnetic should be little as far as possible ", as shown in dotted line in Fig. 2 and Fig. 3, get
, namely
.