CN103986261A - Method for improving gap flux density waveform of permanent magnet synchronous motor - Google Patents

Method for improving gap flux density waveform of permanent magnet synchronous motor Download PDF

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Publication number
CN103986261A
CN103986261A CN201410143274.6A CN201410143274A CN103986261A CN 103986261 A CN103986261 A CN 103986261A CN 201410143274 A CN201410143274 A CN 201410143274A CN 103986261 A CN103986261 A CN 103986261A
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thickness
magnet steel
air gap
magnetic
gap flux
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CN103986261B (en
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刘景林
吴增艳
李世良
杨奔
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Northwestern Polytechnical University
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Northwestern Polytechnical University
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Abstract

The invention relates to a method for improving a gap flux density waveform of a permanent magnet synchronous motor. The thickness of any point in the magnetizing direction of magnetic steel is in linear transition or stepped transition from the maximum value of the center thickness to the minimum value H[min] of the thicknesses of the two sides; it is determined that the widths of magnetic separation air gaps at the two ends of the magnetic steel are 1-1.5 times as large as the minimum thickness of the magnetic steel and it is guaranteed that the length of each magnetic separation air gap satisfies the thickness requirement of a magnetic separation bridge for motor design. The shape of the magnetic steel and the magnetic separation air gaps are designed so that the gap flux density waveform can be of a sinusoid shape. The harmonic content in the reversed electromotive force of the motor is reduced, the motor eddy-current loss is reduced, temperature rise is reduced, efficiency is improved, and the performance of the motor is improved.

Description

A kind of method of improving PMSM Air Gap Flux waveform
Technical field
The invention belongs to technical field of motors, relate in particular to a kind of method of improving PMSM Air Gap Flux waveform
Background technology
Maturation and complete gradually along with designing permanent-magnet synchronous motor exploitation and control technology, and the development of permanent magnet aspect performance and industrialization, permagnetic synchronous motor had both had with it governor control characteristics that direct current machine is good, have again that ac motor structure is simple, easy to maintenance, stable, the advantage of dependable performance is and increasing in the demand of every field, development prospect is become better and better.At present, permagnetic synchronous motor is widely used in various servomotors, wind power generation field, electric automobile driving field and electric main shaft of digital control machine tool motor.
Yet the harmonic content of the interchange winding back electromotive force of the permagnetic synchronous motor of present stage is larger, the fractional slot permanent magnet synchronous motor of especially embedded concentrated winding, the conference of back electromotive force harmonic content causes motor eddy current loss to increase, temperature rise increases, electric efficiency declines, and motor performance is had to comparatively serious impact.The large main cause of permagnetic synchronous motor winding back electromotive force harmonic content is that the waveform sine of air gap flux density of motor is poor, sneaked into more even-order harmonic, make the air gap flux density of motor be rendered as trapezoidal wave, thereby the harmonic content of the back electromotive force of winding can be larger.In the design of salient pole induction machine, designer often adopts the method for non-uniform gap to obtain sinusoidal air gap flux density waveform, yet this method is also inapplicable for permagnetic synchronous motor, so find a kind of method of improving air gap flux density waveform that is applicable to permagnetic synchronous motor, seems particularly important.
Therefore, how improving air-gap field waveform and back emf waveform is those skilled in the art's technical issues that need to address.
Summary of the invention
The technical problem solving
For fear of the deficiencies in the prior art part, the present invention proposes a kind of method of improving PMSM Air Gap Flux waveform, improves the waveform of air gap flux density by the magnet steel of design special shape.
Technical scheme
A method of improving PMSM Air Gap Flux waveform, is characterized in that: design magnet steel shape and every magnetic air gap so that air gap flux density waveform is sinusoid, design procedure is as follows:
Step 1, determine the minimum value H of thickness on magnet steel magnetizing direction minbe 1~3mm, pole embrace α pbe 0.6~0.95;
Step 2: the maximum H that determines thickness on magnet steel magnetizing direction max> H min;
Step 3: on magnet steel magnetizing direction the thickness of any point by the maximum of center thickness the minimum value H to the thickness on both sides min, with linear transitions or stairstepping transition;
Step 4: the width every magnetic air gap of determining magnet steel two ends is 1~1.5 times of magnet steel minimum thickness, every the length of magnetic air gap guarantee design of electrical motor every magnetic bridge thickness requirement.
The maximum of thickness on the magnet steel magnetizing direction of described step 2
The thickness of any point on the magnet steel magnetizing direction of described step 3 wherein: S is that in magnet steel, any point is apart from the peaked distance of thickness on the magnet steel magnetizing direction of magnet steel center line, and L is magnetic pole length.
The described thickness every magnetic bridge is 1~2mm.
Beneficial effect
A kind of method of improving PMSM Air Gap Flux waveform that the present invention proposes, with the thickness of any point on magnet steel magnetizing direction by the maximum of center thickness the minimum value H to the thickness on both sides min, with linear transitions or stairstepping transition; The width every magnetic air gap of determining magnet steel two ends is 1~1.5 times of magnet steel minimum thickness, every the length of magnetic air gap guarantee design of electrical motor every magnetic bridge thickness requirement.The present invention design the shape of magnet steel and every magnetic air gap so that air gap flux density waveform is sinusoid.Reduce the harmonic content in counter electromotive force of motor, reduce motor eddy current loss, reduce temperature rise, raise the efficiency lifting motor performance.
Accompanying drawing explanation
The scenario-frame schematic diagram of Fig. 1: embodiment 1 magnetizing direction thickness sinusoidal variations;
The linear change programme structural representation of Fig. 2: embodiment 2 magnetizing direction thickness;
The linear change programme structural representation of Fig. 3: embodiment 3 magnetizing direction thickness;
In figure, 1 is rotor core, 2 permanent magnets, and 3 every magnetic air gap, 4 interpolar axis, 5 field axis.
Embodiment
Now in conjunction with the embodiments, the invention will be further described for accompanying drawing:
According to magnetic circuit ohm law, can obtain magnetic flux Φ and equal magnetic potential F divided by magnetic resistance R m, under the same pole of motor, magnetic circuit is basic identical, and magnetic resistance is also basic identical, so the large place of magnetic potential will produce larger magnetic flux, also will in air gap, produce larger magnetic close.According to this principle, as long as rationally control the waveform of the magnetic potential of permanent magnet generation, just can control the waveform of unloaded air gap flux density.And the magnetic potential of permanent magnet is directly proportional to the length on permanent magnet magnetizing direction, so the length on appropriate design permanent magnet magnetizing direction just can be controlled the waveform of air gap flux density, reach the object of improving air gap flux density waveform.
In order to obtain sine-shaped air gap flux density waveform, just magnet steel need to be designed to the shape that the thickness on magnetizing direction changes by sinusoid, design process is as follows.
The first step: the minimum value H that determines thickness on magnet steel magnetizing direction minwith pole embrace α p
The minimum value of magnet thickness is mainly subject to the restriction of magnet steel mechanical strength and the magnitude of field intensity needing, and magnet thickness is thicker, and mechanical strength is just stronger, and the magnetic field intensity of generation is also just larger, if but H minexcessive, can cause the maximum H of thickness on magnet steel magnetizing direction maxmeeting is larger, thereby can increase the consumption of permanent magnetic material, and this not only can increase unnecessary cost also can make motor volume also increase.So H minchoose and will consider above factor and choose, selection range is proper between 1-3mm.Pole embrace α pthe performance of motor is had to obvious impact, so α paccording to design requirement, suitably choose, when design of electrical motor, choosing generally of pole embrace chosen based on experience value, and its scope is generally 0.6~0.95.
Second step: the maximum H that determines thickness on magnet steel magnetizing direction max
In order to obtain sine-shaped air gap flux density, H max, H minand α pneed to meet sine relation, so H maxcan ask for according to following formula.
The 3rd step: determine thickness transient process
The thickness of permanent magnet will be H from interior thickness according to certain rule maxplace be transitioned into the thinnest place of thickness, both sides, and in order to obtain approaching most sine-shaped mmf wave, this method adopts sinusoidal rule transition.If any point is S apart from the distance of magnet steel center line in magnet steel, the thickness on this magnet steel magnetizing direction is H (H min< H < H m) a, magnetic pole length is L, on the permanent magnet magnetizing direction of changing the time, thickness H can obtain according to following formula.
The 4th step: design is every magnetic air gap
Due to the permanent magnet thick middle of this construction rotor, both sides are thin, so the leakage field between adjacent two magnetic poles is larger, so be necessary very much to design one, every magnetic air gap, reduce the leakage field between adjacent pole.Should be every magnetic air gap on magnetic pole both sides, be close to permanent magnet, rectangular every magnetic air gap, its thickness is 1-3mm, specifically can adjust according to motor size, length from permanent magnet base until rotor near the edge of motor gas-gap, every magnetic air gap and rotor edge, leave every magnetic bridge, owing to being subject to the restriction of rotor mechanical intensity, every the too thin rotor mechanical intensity meeting of magnetic bridge variation, too thick bad every magnetic effect, according to experiment gained experience, every the thickness of magnetic bridge, be that 1~2mm is comparatively applicable.
The rotor structure designing according to above method can farthest be optimized motor gas-gap magnetic flux density waveforms, thereby reduces the harmonic content of back electromotive force, improves the waveform of back electromotive force, reduce eddy current loss, reduce electric machine temperature rise, improve the efficiency of motor, improve motor performance.
But in the application of general occasion, due to the requirement of rotor magnetic pole profile to processing technology, and the requirement to processing technology in rotor punching manufacturing process, and the restriction of the various factors such as machining accuracy, may more difficult enforcement according to above method, so the method that we provide the second to be relatively easy to realize designs, this method is actually a kind of method of having compromised.
By observing air gap flux density waveform that traditional magnet steel produces, we find, the top of air gap flux density waveform is more flat, even harmonic content is larger, this is also evenly to cause due to magnetic potential that even thickness on magnet steel magnetizing direction produces, so as long as the odd harmonic suitably increasing in permanent magnet magnetic potential waveform just can be improved air gap flux density waveform.The design philosophy of second method that Here it is, it is mainly reflected in second step and the 3rd step from the different of first method.In above-mentioned second step, no longer require H max, H minand α pmust strictly meet formula only need to guarantee H max> H min, the maximum of thickness appears at the centre of magnetic pole simultaneously, and minimum value appears at the both sides of magnetic pole.In the 3rd step, no longer require the transient process must be by sinusoidal rule transition, as long as guarantee that the thickness of permanent magnet magnetizing direction is transitioned into the thinnest place of magnetizing direction thickness, both sides by the thickest place of middle magnetizing direction thickness monotonously, transient process is also not necessarily continuous, can be linear transitions, can be also stairstepping transition.
Specific embodiment is as follows:
Embodiment 1: the first step as required selected suitable pole embrace is α pand the magnet steel side of magnetizing (this example is radial magnetizing) minimum value H of thickness upwards min, wherein choose α p=0.85, H min=2mm.Second step is according to formula calculate the maximum H of thickness on magnet steel magnetizing direction maxfor 8.267mm.The 3rd is H from magnet thickness sinusoidally maxcenter line on be transitioned into the both sides of magnetic pole.The 4th step design, every magnetic air gap, is got 2mm every magnetic air gap thickness in this example, every magnetic air gap and rotor edge leave 1mm every magnetic bridge.This scheme can well be optimized air gap flux density waveform, reduces eddy current loss, improves electric efficiency.The structure chart obtaining by this conceptual design as shown in Figure 1.
Embodiment 2 and embodiment 3: due in actual design due to cost, the strength of materials, the restriction of the factors such as manufacturability, embodiment 1 is more difficult realization comparatively speaking, so can reach again the present second method of object of optimization air gap flux density waveform in order to meet the restriction of each factor, design, this embodiment is actually a kind of compromise to scheme 1.Different from scheme 1, at second step, directly choose H maxfor 7mm, root diameter just can reduce like this.No longer by sinusoidal rule, carry out transition, but directly adopt the transient mode of linear transitions or stairstepping transition to carry out transition simultaneously.This kind of scheme, simplicity of design, is easy to realize, good manufacturability, production cost is also lower comparatively speaking.As shown in Figure 2, the design result of stairstepping transient mode as shown in Figure 3 for the design result of linear transitions mode.
Above design, optimization air gap flux density waveform that can be to a certain degree, improve back emf waveform, reduce the temperature rise of motor, reduce eddy current loss, improve electric efficiency, embodiment 1 best results wherein, but that 2 pairs of processing technologys of embodiment require is lower, and it is easier to implement, so scheme one and scheme two respectively have superiority, and determine while selecting according to use occasion.

Claims (4)

1. a method of improving PMSM Air Gap Flux waveform, is characterized in that: design magnet steel shape and every magnetic air gap so that air gap flux density waveform is sinusoid, design procedure is as follows:
Step 1, determine the minimum value H of thickness on magnet steel magnetizing direction minbe 1~3mm, pole embrace α pbe 0.6~0.95;
Step 2: the maximum H that determines thickness on magnet steel magnetizing direction max> H min;
Step 3: on magnet steel magnetizing direction the thickness of any point by the maximum of center thickness the minimum value H to the thickness on both sides min, with linear transitions or stairstepping transition;
Step 4: the width every magnetic air gap of determining magnet steel two ends is 1~1.5 times of magnet steel minimum thickness, every the length of magnetic air gap guarantee design of electrical motor every magnetic bridge thickness requirement.
2. improve according to claim 1 the method for PMSM Air Gap Flux waveform, it is characterized in that: the maximum of thickness on the magnet steel magnetizing direction of described step 2
3. improve according to claim 1 the method for PMSM Air Gap Flux waveform, it is characterized in that: the thickness of any point on the magnet steel magnetizing direction of described step 3 wherein: S is that in magnet steel, any point is apart from the peaked distance of thickness on the magnet steel magnetizing direction of magnet steel center line, and L is magnetic pole length.
4. improve according to claim 1 the method for PMSM Air Gap Flux waveform, it is characterized in that: the described thickness every magnetic bridge is 1~2mm.
CN201410143274.6A 2014-04-10 2014-04-10 A kind of method improving PMSM Air Gap Flux waveform Active CN103986261B (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105449978A (en) * 2015-10-19 2016-03-30 安徽大学 Iron-core-free permanent magnet synchronous linear motor with arc permanent magnet
CN107147224A (en) * 2017-06-30 2017-09-08 广东美芝制冷设备有限公司 Stator core and stator, motor and compressor with the stator core
CN107171462A (en) * 2017-06-30 2017-09-15 广东美芝制冷设备有限公司 Motor and the compressor with the motor
CN112751435A (en) * 2020-12-28 2021-05-04 哈尔滨宇龙自动化有限公司 Magnetic integrated eccentric magnetic pole structure of external rotor hub motor
CN113949185A (en) * 2021-10-15 2022-01-18 浙江中车尚驰电气有限公司 Rotor punching sheet compatible with high speed and low speed, rotor and motor thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006325348A (en) * 2005-05-19 2006-11-30 Nidec Shibaura Corp Rotor
CN101686002A (en) * 2008-09-27 2010-03-31 上海特波电机有限公司 Design method of high power density permanent magnet motor
CN102157998A (en) * 2011-03-25 2011-08-17 上海大学 Rotor of built-in permanent magnet motor and magnetic steel structural parameter determining method thereof
CN102457114A (en) * 2010-11-02 2012-05-16 株式会社安川电机 Rotary electric machine
JP5159153B2 (en) * 2007-04-25 2013-03-06 東芝産業機器製造株式会社 Rotating electric machine rotor and rotating electric machine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006325348A (en) * 2005-05-19 2006-11-30 Nidec Shibaura Corp Rotor
JP5159153B2 (en) * 2007-04-25 2013-03-06 東芝産業機器製造株式会社 Rotating electric machine rotor and rotating electric machine
CN101686002A (en) * 2008-09-27 2010-03-31 上海特波电机有限公司 Design method of high power density permanent magnet motor
CN102457114A (en) * 2010-11-02 2012-05-16 株式会社安川电机 Rotary electric machine
CN102157998A (en) * 2011-03-25 2011-08-17 上海大学 Rotor of built-in permanent magnet motor and magnetic steel structural parameter determining method thereof

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105449978A (en) * 2015-10-19 2016-03-30 安徽大学 Iron-core-free permanent magnet synchronous linear motor with arc permanent magnet
CN107147224A (en) * 2017-06-30 2017-09-08 广东美芝制冷设备有限公司 Stator core and stator, motor and compressor with the stator core
CN107171462A (en) * 2017-06-30 2017-09-15 广东美芝制冷设备有限公司 Motor and the compressor with the motor
CN112751435A (en) * 2020-12-28 2021-05-04 哈尔滨宇龙自动化有限公司 Magnetic integrated eccentric magnetic pole structure of external rotor hub motor
CN113949185A (en) * 2021-10-15 2022-01-18 浙江中车尚驰电气有限公司 Rotor punching sheet compatible with high speed and low speed, rotor and motor thereof

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