CN114629322A - Large-diameter stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes - Google Patents

Large-diameter stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes Download PDF

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Publication number
CN114629322A
CN114629322A CN202210338491.5A CN202210338491A CN114629322A CN 114629322 A CN114629322 A CN 114629322A CN 202210338491 A CN202210338491 A CN 202210338491A CN 114629322 A CN114629322 A CN 114629322A
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rotor
stator
motor
eccentric
pole
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漆亚梅
王恺
李铁才
黄发章
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Shenzhen Tiger Motion Control Technology Co ltd
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Shenzhen Tiger Motion Control Technology Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
    • H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
    • H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/16—Stator cores with slots for windings
    • H02K1/165—Shape, form or location of the slots
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/27—Rotor cores with permanent magnets
    • H02K1/2706—Inner rotors
    • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
    • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
    • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
    • H02K1/278—Surface mounted magnets; Inset magnets
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
    • H02K3/28—Layout of windings or of connections between windings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2201/00—Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits
    • H02K2201/03—Machines characterised by aspects of the air-gap between rotor and stator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2201/00—Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits
    • H02K2201/06—Magnetic cores, or permanent magnets characterised by their skew
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
    • H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)

Abstract

The invention relates to a large-diameter stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor adopting fractional slot concentrated windings, which solves the problem of positioning torque of the existing motor, wherein the number of slots of the motor Z is 9N, the number of poles 2P is 8N or the number of poles 2P is 10N, and the winding coefficient is 0.945; the number of slots Z is 15N, the number of poles 2P is 14N or the number of poles 2P is 16N, and the winding coefficient is 0.951; the number of slots Z is 21N, the number of poles 2P is 20N or the number of poles 2P is 22N, and the winding coefficient is 0.953; the number of slots Z is 27N, the number of poles 2P is 26N or the number of poles 2P is 28N, and the winding coefficient is 0.954; wherein N is 2, 3, 4, 5.; the length of the equivalent uniform air gap between the stator and the rotor is: δ ═ R1‑r1Is 0.2 to 10mm. The number q of slots of each pole and each phase of the motor is equal to Z/(2Pm) and is less than or equal to 1/2, and the motor is a fractional slot concentrated winding motor.

Description

Large-diameter stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes
Technical Field
The invention discloses a three-phase permanent magnet servo motor, in particular to a large-diameter non-uniform air gap three-phase permanent magnet servo motor with pole shoes, stators and rotors, and double eccentricity, which is suitable for direct drive and position and speed servo control application.
Background
Permanent magnet motors can be classified into two broad categories, sine waves and square waves, according to the drive current and back emf waveforms.
The torque fluctuation of the sine wave permanent magnet motor is much smaller than that of the square wave permanent magnet motor, and the sine wave permanent magnet motor becomes the mainstream of industrial application nowadays. However, in order to reduce torque ripple of the conventional sine wave permanent magnet motor, a "fractional-slot distributed winding structure" is adopted. The air gap harmonic magnetic field and the positioning torque of the 'fractional-slot distributed winding motor' are small, but the structure and the manufacturing process of the motor are complicated, and in addition, the control system of the sine wave permanent magnet motor is complicated, so that the cost of the motor is greatly increased, and more importantly, the force and energy index of the motor is also reduced.
In order to solve the problems of high cost, complicated structure and process of the fractional-slot distributed winding motor, when the sinusoidal wave permanent magnet motor starts to adopt the fractional-slot concentrated winding structure, the most typical examples are as follows: a 10-pole, 12-slot "fractional-slot concentrated winding motor". Because the pole number of the fractional-slot concentrated winding motor is very close to the slot number, and the positioning torque (cogging positioning torque) of the fractional-slot concentrated winding motor is relatively large, the greatest design and manufacturing difficulties of the concentrated winding motor are as follows: how to reduce its cogging torque. Although the research is not few at home and abroad, the methods are numerous, but the methods all need to pay the premise of sacrificing other properties and have poor effect. The reason is analyzed as follows:
because the pole number of the fractional-slot concentrated winding motor is very close to the slot number, the winding coefficient of the fractional-slot concentrated winding motor is very large, namely the winding utilization rate is very high, the winding end is minimized, the copper loss of the motor is small, and the efficiency is high. But the cogging torque of a fractional slot concentrated winding motor can be very large and difficult to suppress. In the limit condition, the positioning torque reaches the maximum value when the number of poles is equal to the number of grooves. The traditional method is as follows: selecting reasonable tooth space fit, adopting a closed slot or a small slot, properly enlarging an air gap, adopting a rotor chute, adopting rotor eccentricity and the like, wherein the method is commonly used for inhibiting the positioning torque. However, the above method causes the winding coefficient to be smaller, the magnetic leakage to be larger, the air gap magnetic density to be smaller, and the material utilization rate of the motor to be reduced, so that the mechanical performance index and performance of the motor are sacrificed, and the positioning torque is not enough to be restrained to be less than several ten-thousandths of an order of magnitude. Even if the above methods are used simultaneously in many electric machines for engineering applications, it is difficult to suppress the cogging torque to an order of magnitude smaller than ten-thousandths. Therefore, restraining the cogging torque is still a big problem in the design and manufacture of the current permanent magnet motor. In particular, the conventional "fractional-slot distributed winding structure" is still adopted in the large-diameter torque motor in the direct drive system, although the motor structure and the manufacturing process are complicated and the production cost is high.
Disclosure of Invention
Aiming at the defects that the positioning torque and force energy indexes of the permanent magnet motor in the prior art cannot be considered at the same time, or the defects of complex structure and manufacturing process and high production cost exist, the invention provides the large-diameter stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with the pole shoes.
The technical scheme adopted by the invention for solving the technical problems is as follows: a large-diameter non-uniform air gap three-phase permanent-magnet servo motor with pole shoe, stator and rotor is characterized by that said motor is an internal rotor motor, more than one pair of permanent magnets are mounted on the rotor, three-phase windings are mounted in the slots of the stator,
the motor is a fractional slot concentrated winding motor with the number q of slots of each pole and each phase being equal to Z/(2Pm) and less than or equal to 1/2, wherein Z is the number of slots, 2P is the number of poles, and m is the number of phases;
the number of slots Z is 9N, the number of poles 2P is 8N or the number of poles 2P is 10N, and the winding coefficient is 0.945;
the number of slots Z is 15N, the number of poles 2P is 14N or the number of poles 2P is 16N, and the winding coefficient is 0.951;
the number of slots Z is 21N, the number of poles 2P is 20N or the number of poles 2P is 22N, and the winding coefficient is 0.953;
the number of slots Z is 27N, the number of poles 2P is 26N or the number of poles 2P is 28N, and the winding coefficient is 0.954;
a natural number greater than or equal to 2;
the rotor core of the motor is an eccentric rotor core,
eccentricity P of rotorr＝r1/r2＝(1.05～(1+2δcos(180°/2P))，
Wherein r is1Is the rotor radius, r2Is the radius of the eccentric rotor and,
the stator core of the motor is an eccentric stator core,
eccentricity P of statorR＝R1/R2＝(0.95～1/(1+δcos(180°/Z)))，
Wherein R is1Is the stator radius, R2Is the eccentric stator radius, the pitch angle theta is 360/Z,
the motor is a stator-rotor double-eccentric non-uniform air gap motor,
the permanent magnet rotor is provided with pole shoes.
The technical scheme adopted by the invention for solving the technical problem further comprises the following steps:
the permanent magnet is square magnetic steel, the permanent magnet is embedded between a pole shoe and a rotor yoke, and the length of an equivalent uniform air gap between the stator and the rotor is as follows: δ ═ R1-r1And is 0.2 to 3mm,
the rotor core of the motor is an eccentric rotor core,
eccentricity P of rotorr＝r1/r2＝(1.05～(1+1.5δcos(180°/2P))，
Wherein r is1Is the rotor radius, r2Is inclined toThe radius of the core rotor is greater than the radius of the core rotor,
the stator core of the motor is an eccentric stator core,
eccentricity P of statorR＝R1/R2＝(0.95～1/(1+0.95δcos(180°/Z))，
Wherein R is1Is the stator radius, R2Is the eccentric stator radius and the pitch angle theta is 360/Z.
The pole shoe is made of low-carbon steel or cast steel, silicon steel sheets, ferrite, SMC composite soft magnetic materials or other soft magnetic materials.
The magnetic steel is positioned by a die and then is bonded with the square magnetic steel, the pole shoe and the rotor yoke when the grooves are not formed in the pole shoe and the rotor yoke.
The rotor core or two axial end faces of the rotor core adopt rotor end pieces with pole shoes and a rotor yoke integrated, and the square magnetic steel, the pole shoes and the rotor yoke are embedded into one another through the rotor end pieces to form the integral rotor core.
The rotor end sheets are made of silicon steel sheets or other metal or nonmetal composite materials with high strength, the number of the rotor end sheets with the pole shoes integrated with the rotor yoke is more than 2, and the thickness of the rotor end sheets is 0.35-2.1 mm.
The rotor end sheet is made of silicon steel sheets the same as the rotor yoke, and the width Q of the magnetic bridge is not more than delta.
The rotor core comprises square magnetic steel, pole shoes, a rotor yoke and T-shaped wedge blocks, grooves are formed in the pole shoes and the rotor yoke respectively, the pole shoes and the rotor yoke are connected together in an adhering and embedding mode through the square magnetic steel, wedge grooves used for inserting the rotor yoke of the T-shaped wedge blocks are formed in the two sides of the groove for installing the magnetic steel in the rotor yoke, when the T-shaped wedge blocks are inserted into the wedge grooves of the rotor yoke along the axial direction, the square magnetic steel, the pole shoes and the rotor yoke can be connected together in an embedding mode to form a firm rotor core which is integrally connected in an embedding mode, and anaerobic glue or epoxy glue is applied to each joint portion.
The stator core is formed by assembling Z identical pole slots, the stator core is assembled through inner circle or outer circle positioning, and the Z identical stator pole slots have identical eccentricity.
The beneficial effects of the invention are: the method for increasing the pole shoe by matching the stator and the rotor double-eccentric structure can well inhibit the positioning torque, reduce the air gap harmonic magnetic field and comprehensively improve the performance of the motor in all aspects, and is suitable for both square wave and sine wave permanent magnet motors and is particularly suitable for large-diameter torque motors in a direct drive system. According to the stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor, the positioning torque can be better inhibited, the air gap harmonic magnetic field is reduced, and the performances of the motor in all aspects are comprehensively improved by adding the rotor pole shoes. The method is suitable for both square wave and sine wave permanent magnet motors, and is particularly suitable for large-diameter torque motors in direct drive systems.
The three-phase permanent magnet servo motor has the advantages of concentrated windings, can be driven by three-phase square wave current or three-phase sine wave current, can generate stable torque, and has a series of advantages of minimized winding end, minimized air gap, minimized material, minimized positioning torque, minimized loss and the like.
The invention will be further described with reference to the accompanying drawings and specific embodiments.
Drawings
Fig. 1 is a schematic view of an eccentric structure of a rotor of a motor in a preferred embodiment of the present invention.
Fig. 2 is a schematic view of an eccentric structure of a stator of a motor according to a preferred embodiment of the present invention.
Fig. 3 is a schematic view of the eccentric structure of a stator of a 12-slot 10-pole motor according to a preferred embodiment of the present invention.
Fig. 4 is an assembly schematic diagram of an electrodeless boot double-eccentric 10-pole 12-slot motor.
Figure 5 is an assembly schematic of another pole-piece-free double eccentric 10-pole 12-slot machine.
Fig. 6 is a schematic view of a rotor core structure of a 10-pole 12-slot motor with pole shoes.
Fig. 7 is a schematic view of two magnetic pole configurations of a rotor with pole shoes.
Fig. 8 is a schematic view of two types of pole-shoe rotor yokes.
Fig. 9 is a drawing of a 10-pole 12-slot motor lamination with pole shoe rotor eccentricity.
Fig. 10 is a schematic view of a 10-pole, 12-slot motor assembly using 3 end pieces with pole shoe rotor eccentricity.
Fig. 11 is a schematic structural view of a stator core in which 12 identical pole slots Z are assembled.
Fig. 12 is a schematic diagram of a stator lamination of a torque motor with an eccentric large-diameter stator having a slot number Z of 9N of 36.
Fig. 13 is a schematic diagram of a stator lamination of a large-diameter rotor with pole shoes and an eccentric torque motor with the pole number 2P-8N-32.
Fig. 14 is a stator eccentricity parameter diagram for a 10 pole, 12 slot preferred embodiment motor.
Figure 15 is a schematic view of a 10 pole 12 slot preferred embodiment rotor with pole shoes and a double eccentric motor.
Fig. 16 is a diagram showing a cogging torque waveform without using an eccentric one pole.
Fig. 17 is a diagram of the cogging torque waveform for the next pole after rotor eccentricity is used.
Fig. 18 is a cogging torque waveform for the next pole after double eccentricity of the rotor and stator.
Fig. 19 is a diagram of a cogging torque waveform for a pole shoe without eccentricity of one pole.
Fig. 20 is a diagram of a cogging torque waveform for the next pole following pole shoe application of rotor eccentricity.
Fig. 21 is a diagram of the cogging torque waveform for the next pole with the pole shoe using double eccentricity of the rotor and stator.
In the figure, 1-stator iron core, 2-rotor iron core, 3-rotor yoke, 4-pole shoe, 5-rotor end piece, 6-square magnetic steel, 7-rotor component, 8-rotor punching piece, 9-wedge groove, 10-T-shaped wedge block and 11-magnetic bridge.
Detailed Description
The present embodiment is a preferred embodiment of the present invention, and other principles and basic structures that are the same as or similar to the present embodiment are within the scope of the present invention.
The invention aims to solve the problems of the existing square wave permanent magnet motor and sine wave permanent magnet motor, and provides a stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor which adopts a new design principle, a new structure, high performance and low cost and adopts fractional slot concentrated windings.
In order to solve the problem that the positioning torque of the existing square wave permanent magnet servo motor and sine wave permanent magnet servo motor is larger, in the invention, the motor is a fractional slot concentrated winding motor with the number q of slots of each pole and each phase being equal to Z/(2Pm) being less than or equal to 1/2, wherein q is the number of slots of each pole and each phase, Z is the number of slots, 2P is the number of poles, and m is the number of phases;
the number of slots Z is 9N, the number of poles 2P is 8N or the number of poles 2P is 10N, and the winding coefficient is 0.945;
or the number of slots Z is 15N, the number of poles 2P is 14N or the number of poles 2P is 16N, and the winding coefficient is 0.951;
or the number of the slots Z is 21N, the number of the poles 2P is 20N or the number of the poles 2P is 22N, and the winding coefficient is 0.953;
or the number of slots Z is 27N, the number of poles 2P is 26N or the number of poles 2P is 28N, and the winding coefficient is 0.954;
n is 2, 3, 4, 5.. i.e. N is greater than or equal to 2;
the rotor core 2 of the motor is an eccentric rotor core 2, and the eccentricity ratio P of the rotorr＝r1/r2(1.05- (1+2 δ cos (180 °/2P))), wherein r is1Is the rotor radius, r2Is the radius of the eccentric rotor and,
the stator core 1 of the motor is an eccentric stator core 1, and the eccentricity ratio P of the statorR＝R1/R2(0.95-1/(1 + δ cos (180 °/Z)), wherein R is1Is the stator radius, R2Is the radius of the eccentric stator,
the motor is a stator-rotor double eccentric non-uniform air gap motor, as shown in fig. 4 and 5.
When eccentricity Pr＝PRWhen 1, r1＝r2，R1＝R2When the stator and the rotor are not eccentric, the motor with the non-uniform air gap is changed into the motor with the uniform air gap, and the length of the equivalent uniform air gap is equal to that of the motor with the uniform air gapThe method comprises the following steps: delta ═ R1-r1。
Because the pole number of the fractional-slot concentrated winding motor is very close to the slot number, the winding coefficient of the fractional-slot concentrated winding motor is very large, namely the winding utilization rate is very high. But the cogging torque of a fractional slot concentrated winding motor can be very large and difficult to suppress. The limit of this structure is that the detent torque reaches a maximum value when the number of poles is equal to the number of slots.
The traditional method is as follows: selecting reasonable tooth space fit, adopting a closed slot or a small slot, properly enlarging an air gap, adopting a rotor chute, adopting rotor eccentricity and the like, wherein the method is commonly used for inhibiting the positioning torque. However, the above method causes the winding coefficient to be smaller, the magnetic leakage to be larger, the air gap magnetic density to be smaller, and the material utilization rate of the motor to be reduced, so that the mechanical performance index and performance of the motor are sacrificed, and the positioning torque is not enough to be restrained to be less than several ten-thousandths of an order of magnitude. Even if the above methods are used simultaneously in many electric machines for engineering applications, it is difficult to suppress the cogging torque to an order of magnitude smaller than ten-thousandths.
Selecting a reasonable tooth socket fit: the closer the pole number and the slot number are, the larger the winding coefficient is, the higher the utilization rate of the winding is, but the larger the positioning moment is possibly, and in the traditional method, the two are incompatible contradictions. The invention adopts the non-uniform air gap structure of double eccentricity of the stator and the rotor and the electromagnetic design, so that the capability of inhibiting the positioning moment is multiplied, and the tooth grooves with the closest pole number and groove number can be adopted to be matched, for example:
in the invention, the number of grooves Z is 9N, the number of poles 2P is 8N or the number of poles 2P is 10N, wherein N is 2, 3, 4, 5. The length of the equivalent uniform air gap between the stator and the rotor is: delta ═ R1-r1Is 0.2 to 10 mm. The winding factor of the motor is 0.945. When N is bigger, the diameter of the motor is bigger, and at the moment, the length of the equivalent uniform air gap can be bigger. The best embodiment of the invention is as follows: the slot number Z is 9N 36, the pole number 2P is 32, the torque motor with the stator core 1 outer diameter of 360mm is taken as an example, and the positioning torque of the motor is better than 0.006 Nm.
The present invention will be described in detail below with reference to a specific example:
in this embodiment, a motor having a slot number Z of 12 and a pole number 2P of 10 is taken, and the length of an equivalent uniform air gap between a stator and a rotor of the motor is: delta ═ R1-r1Is 0.2 to 2 mm. The winding coefficient of the motor is 0.933, and the positioning torque of the motor is better than 0.00045 Nm.
To illustrate the influence of eccentricity on the suppression of cogging torque, a motor with a slot number Z of 12, a pole number 2P of 10, an air gap δ of 0.4mm, a notch of 0.2mm, and an outer diameter of 110mm is taken as an example:
(1) when the eccentricity is not adopted and the air gap is uniform, the slot number and the pole number are relatively close, even if the optimal pole slot matching is adopted and the optimal air gap is matched with the size of the notch, the positioning torque of the motor is still 0.011Nm, and the positioning torque waveform under one magnetic pole is shown in figure 16. The positioning moment waveform is formed by superposing a main wave with larger amplitude and a secondary wave with smaller amplitude and caused by slotting. The cogging torque wave is a double frequency harmonic with respect to a pair of magnetic pole waves.
(2) When the rotor eccentricity is adopted, even if the eccentricity ratio is larger, the optimal positioning moment is 0.0026Nm, the waveform of the positioning moment is as shown in figure 17, but the amplitude of the positioning moment is reduced by 4.3 times at the moment, and secondary waves caused by slotting are basically and completely inhibited. However, for high performance motors, the detent torque index is not optimal enough.
(3) Further, the double eccentricity of the rotor and the stator is adopted, even if the eccentricity is not too large, the positioning moment can be optimized to be 0.00045Nm, and the waveform of the positioning moment is shown in figure 18. It can be seen that, with double eccentricity of the rotor and the stator, the magnitude of the positioning moment is reduced by 13.4 times compared with that without eccentricity, and the frequency is multiplied. The eccentricity of the rotor and the stator is not too large when the rotor and the stator are doubly eccentric, so that the non-uniform air gap and the non-eccentric uniform air gap are not obviously changed. Therefore, the average air gap flux density of the non-uniform air gap motor does not change obviously with no eccentric uniform air gap. That is, with a motor with double eccentricity of the rotor and the stator, the average air gap flux density is reduced very little.
The three-phase permanent magnet servo motor has r as the permanent magnet rotor is eccentric1>r2Radius of rotor r1Greater than the radius r of the eccentric rotor2The effect is similar to that of a circular arc chamfer. Obviously, the utilization rate of the permanent magnet steel is reduced, the processing cost of the arc permanent magnet is higher, and in order to reduce the cost and improve the utilization rate of the magnetic steel, in the invention, the permanent magnet rotor is provided with a pole shoe 4, the permanent magnet is square magnetic steel 6, the permanent magnet is embedded between the pole shoe 4 and a rotor yoke 3, and the equivalent uniform air gap between the stator and the rotor has the length: delta ═ R1-r1Is 0.2 to 3 mm.
After the rotor is provided with the pole shoes 4, the square magnetic steel 6 can be used, and the cost of the magnetic steel can be reduced by about 25 percent. More important to the invention is that the principle electromagnetic air gap of the machine is substantially reduced after the rotor is provided with pole shoes 4. The reason is that if the rotor does not have the pole shoe 4, the magnetic permeability of the magnetic steel is close to that of air, so the principle electromagnetic air gap of the radial magnetic circuit should include the thickness of the magnetic steel, and after the rotor has the pole shoe 4, the thickness of the magnetic steel is reduced by one because the principle electromagnetic air gap of the motor is greatly reduced. Obviously, when the principle electromagnetic air gap is small, the relative change of the eccentricity to the principle electromagnetic air gap is large by adopting the eccentricity of the rotor and the stator, so that the eccentricity is more sensitive to restraining the positioning moment. Namely, the optimal design of the positioning moment and the better optimization effect can be achieved through smaller eccentricity change. The eccentricity ratio is small, and the influence of the air gap flux density is smaller, so that after the rotor is provided with the pole shoes 4, the rotor and the stator are in double eccentricity, and the influence on the air gap flux density is smaller than that of a traditional motor.
As analyzed above, the influence of eccentricity is more sensitive after the pole shoes 4 are arranged, the rotor core 2 of the motor is the eccentric rotor core 2, and the rotor eccentricity P of the motor with the pole shoes 4 isr＝r1/r2(1.05- (1+1.5 δ cos (180 °/2P))), wherein r is1Is the rotor radius, r2Is the eccentric rotor radius.
The stator core 1 of the motor is an eccentric stator core 1, and the stator eccentricity ratio P of the motor with pole shoes 4R＝R1/R2(0.95-1/(1 + 0.95. delta. cos (180 °/Z))), wherein R represents1Is the stator radius, R2Is eccentric toSub-radius, pitch angle θ is 360/Z.
In this embodiment, in the three-phase permanent magnet servo motor, the pole shoe 4 is made of one of low-carbon steel, cast steel, a silicon steel sheet, ferrite, SMC composite soft magnetic material or other soft magnetic materials, the pole shoe 4 and the rotor yoke 3 are respectively provided with a groove, so that the pole shoe 4 and the rotor yoke 3 are bonded into the integral rotor core 2 through the square magnetic steel 6, and the used bonding agent can be anaerobic adhesive or epoxy adhesive special for the magnetic steel; in order to simplify the production process or for a small-sized motor, the square magnetic steel 6, the pole shoe 4 and the rotor yoke 3 can be bonded after being positioned by a die, and at the moment, grooves do not need to be arranged on the pole shoe 4 and the rotor yoke 3.
In this embodiment, in the above three-phase permanent magnet servo motor, at least two axial end faces of the rotor core 2 of the integral rotor core 2 use the rotor end plates 5 with the pole shoes 4 and the rotor yoke 3 integrated into one, the square magnetic steel 6, the pole shoes 4 and the rotor yoke 3 are embedded into each other through the rotor end plates 5 to form the integral rotor core 2, and the rotor end plates 5 may be made of silicon steel sheets or other metal or nonmetal composite materials with large strength; for a motor with a longer axial length, in order to increase strength, the number of the rotor end plates 5 with the pole shoes 4 integrated with the rotor yoke 3 is not limited to 2-3, and can be even more, and the thickness of the rotor end plates 5 is 0.35-2.1 mm. In this embodiment, a rotor punching sheet 8 is arranged between adjacent rotor end sheets 5.
In this embodiment, in order to simplify and maintain the consistency of the process, in the three-phase permanent magnet servo motor, the rotor end plates 5 are made of the same silicon steel sheet as the rotor yoke 3, and the width Q of the magnetic bridge 11 is not greater than δ in order to reduce magnetic leakage.
In this embodiment, in order to simplify the assembly of the three-phase permanent magnet servo motor, the rotor core 2 is formed of: the square magnetic steel 6, the pole shoe 4, the rotor yoke 3 and the T-shaped wedge 10 are formed, grooves are respectively formed in the pole shoe 4 and the rotor yoke 3, so that the pole shoe 4 and the rotor yoke 3 are bonded and embedded together through the square magnetic steel 6, wedge grooves 9 used for inserting the rotor yoke 3 of the T-shaped wedge 10 are formed in the two sides of the groove formed in the rotor yoke 3 and used for inserting the T-shaped wedge 10, when the T-shaped wedge 10 is axially inserted into the wedge grooves 9 of the rotor yoke 3, the square magnetic steel 6, the pole shoe 4 and the rotor yoke 3 can be embedded and embedded together to form a firm rotor core 2 which is integrally embedded and embedded mutually, and in order to increase strength, anaerobic glue or epoxy glue can still be applied to each joint part.
To further illustrate the eccentricity after the rotor has the pole shoe 4, and analyze the influence of the eccentricity on the suppression of the cogging torque, a motor with a slot number Z of 12, a pole number 2P of 10, an air gap δ of 0.4mm, a slot opening of 0.2mm, and an outer diameter of 110mm is taken as an example.
(1) When the motor rotor is provided with the pole shoe 4, eccentricity is not adopted, and the gap is uniform, because the number of slots is close to the number of poles, even if the optimal pole slot matching is adopted, the optimal gap is matched with the size of the notch, the positioning torque of the motor is still 0.010Nm, the motor is not practical, and the positioning torque waveform under one magnetic pole is as shown in figure 19. The positioning torque waveform mainly comprises the following components: a primary wave with larger amplitude is superposed with a secondary wave with smaller amplitude caused by slotting, and the positioning moment wave is a double-frequency harmonic wave relative to a pair of magnetic pole waves.
(2) When the rotor is provided with the pole shoes 4, the rotor eccentricity is adopted, even if the eccentricity ratio is larger, the optimal positioning moment is 0.001Nm, the waveform of the positioning moment is as shown in figure 20, but the amplitude of the positioning moment is reduced by 10 times, and the secondary wave caused by slotting is basically and completely inhibited. The positioning torque index of the high-performance motor is not optimal enough.
(3) When the motor rotor is provided with the pole shoe 4, the double eccentricity of the rotor and the stator is adopted, even if the eccentricity is not too large, the positioning torque can be designed to be 0.00059Nm, the waveform of the positioning torque is shown in a graph 21, the amplitude of the positioning torque is reduced by 17.6 times compared with that of the positioning torque without the eccentricity, and the frequency is multiplied. It can be seen that the rotor has the pole shoe 4, the effect of restraining the positioning moment is better after the rotor and the stator are double-eccentric, and the average air gap flux density of the non-uniform air gap motor is almost the same as that of the non-eccentric uniform air gap motor because the eccentricity of the rotor and the stator is not too large and the non-uniform air gap and the non-eccentric uniform air gap are not obviously changed. That is, the average air gap flux density is reduced very little by adopting the motor with double eccentric rotor and stator.
In this embodiment, the stator core 1 of the three-phase permanent magnet servo motor is assembled by Z identical pole slots 10, as shown in fig. 11. The stator core 1 is assembled by positioning an inner circle or an outer circle, and the Z identical stator pole slots 10 have the same eccentricity.
One preferred embodiment of the present invention is shown in fig. 3, 9, 10, and 14. It can be seen from the figure that this three-phase brushless permanent magnet dc motor is a fractional slot concentrated winding motor with slot number q per pole per phase Z/(2Pm) 12/10m 12/30 ≤ 1/2, where the slot number Z is 12, the pole number 2P is 10, and the phase number m is 3.
The rotor core 2 of the motor is an eccentric rotor core 2, and the eccentricity ratio P of the rotorr＝r1/r22.02 where the radius r of the rotor is 1.05 to (1+1.5 δ cos (180 °/2P)), is taken142mm, eccentric rotor radius r2＝21mm。
The stator core 1 of the motor is an eccentric stator core 1, and the eccentricity ratio P of the statorR＝R1/R20.794 where the stator radius R is 0.95 to 1/(1+0.95 δ cos (180 °/Z))140.50mm, eccentric stator radius R253.50 mm. Figure 15 is a schematic view of the rotor with pole shoes 4 and the double eccentric motor of the preferred embodiment of the present embodiment 10 poles and 12 slots. The positioning torque can reach less than 593.5e-6Nm, as shown in FIG. 21.
The motor is a non-uniform air gap motor with double eccentricity of a stator and a rotor. When eccentricity P isr＝PRWhen 1, r1＝r2，R1＝R2When the stator and the rotor are not eccentric, the motor with the non-uniform air gap is changed into the motor with the uniform air gap, and the length of the equivalent uniform air gap is as follows: delta ═ R1-r1＝0.5mm。
A preferred embodiment of the present invention is shown in fig. 12 and 13. It can be seen from the figure that this three-phase brushless permanent magnet dc motor is a fractional slot concentrated winding motor with slot number q-Z/(2 Pm) -36/32 m-36/96-0.375-1/2 per pole per phase, where the slot number Z-9N-36, the pole number 2P-8N-32, and the phase number m is 3. In the preferred embodiment of the invention, 32 poles and 36 slots are adopted, the rotor is provided with pole shoes 4, and the motor adopts stator and rotor double eccentricity. The positioning moment of the large-diameter moment with the diameter D being 360mm can reach the order of less than ten-thousandths.
According to the stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor, the positioning torque can be better inhibited, the air gap harmonic magnetic field is reduced, and the performances of the motor in all aspects are comprehensively improved by adding the rotor pole shoe 4. The method is suitable for both square wave and sine wave permanent magnet motors, and is particularly suitable for large-diameter torque motors in direct drive systems.
The three-phase permanent magnet servo motor has the advantages of concentrated windings, can be driven by three-phase square wave current or three-phase sine wave current, can generate stable torque, and has a series of advantages of minimized winding end, minimized air gap, minimized material, minimized positioning torque, minimized loss and the like.

Claims (9)

1. The utility model provides a two eccentric inhomogeneous air gap three-phase permanent magnet servo motor of major diameter area pole shoe stator rotor, the motor is inner rotor motor, is equipped with more than a pair of permanent magnet on the rotor, and the groove of stator is adorned three-phase winding, its characterized in that:
the motor is a fractional slot concentrated winding motor with the number q of slots of each pole and each phase being equal to Z/(2Pm) and less than or equal to 1/2, wherein Z is the number of slots, 2P is the number of poles, and m is the number of phases;
the number of slots Z is 9N, the number of poles 2P is 8N or the number of poles 2P is 10N, and the winding coefficient is 0.945;
the number of slots Z is 15N, the number of poles 2P is 14N or the number of poles 2P is 16N, and the winding coefficient is 0.951;
the number of slots Z is 21N, the number of poles 2P is 20N or the number of poles 2P is 22N, and the winding coefficient is 0.953;
the number of slots Z is 27N, the number of poles 2P is 26N or the number of poles 2P is 28N, and the winding coefficient is 0.954;
a natural number greater than or equal to 2;
the rotor core of the motor is an eccentric rotor core,
eccentricity P of rotorr＝r1/r2＝(1.05～(1+2δcos(180°/2P))，
Wherein r is1Is the rotor radius, r2Is the radius of the eccentric rotor and,
the stator core of the motor is an eccentric stator core,
eccentricity P of statorR＝R1/R2＝(0.95～1/(1+δcos(180°/Z)))，
Wherein R is1Is the stator radius, R2Is the eccentric stator radius, the pitch angle theta is 360/Z,
the motor is a stator-rotor double-eccentric non-uniform air gap motor,
the permanent magnet rotor is provided with pole shoes.
2. The large-diameter non-uniform air gap three-phase permanent magnet servo motor with pole shoes, stators and rotors double eccentric as claimed in claim 1, wherein: the permanent magnet is square magnetic steel, the permanent magnet is embedded between a pole shoe and a rotor yoke, and the length of an equivalent uniform air gap between the stator and the rotor is as follows: δ ═ R1-r1And is 0.2 to 3mm,
the rotor core of the motor is an eccentric rotor core,
eccentricity P of rotorr＝r1/r2＝(1.05～(1+1.5δcos(180°/2P))，
Wherein r is1Is the rotor radius, r2Is the radius of the eccentric rotor and,
the stator core of the motor is an eccentric stator core,
eccentricity P of statorR＝R1/R2＝(0.95～1/(1+0.95δcos(180°/Z))，
Wherein R is1Is the stator radius, R2Is the eccentric stator radius and the pitch angle theta is 360/Z.
3. The large-diameter non-uniform air gap three-phase permanent magnet servo motor with pole shoes, stators and rotors double eccentric as claimed in claim 1, wherein: the pole shoe is made of low-carbon steel or cast steel, silicon steel sheets, ferrite, SMC composite soft magnetic materials or other soft magnetic materials.
4. The large-diameter non-uniform air gap three-phase permanent magnet servo motor with pole shoes, stators and rotors double eccentric as claimed in claim 1, wherein: the magnetic steel is positioned by a die and then is bonded with the square magnetic steel, the pole shoe and the rotor yoke when the grooves are not formed in the pole shoe and the rotor yoke.
5. The large-diameter stator-rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes as claimed in any one of claims 1-4, wherein two axial end faces of the rotor core or the rotor core are rotor end pieces with the pole shoes and the rotor yoke integrated, and the square magnetic steel, the pole shoes and the rotor yoke are embedded into a whole rotor core through the rotor end pieces.
6. The large-diameter stator-rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes as claimed in any one of claims 1-4, wherein the rotor end sheets are made of silicon steel sheets or other high-strength metal or non-metal composite materials, the number of the rotor end sheets with the pole shoes integrated with the rotor yoke is more than 2, and the thickness of the rotor end sheets is 0.35-2.1 mm.
7. The large-diameter stator-rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes as claimed in claim 5, wherein the rotor end plates are made of the same silicon steel plates as the rotor yoke, and the width Q of the magnetic bridge is less than or equal to delta.
8. The large-diameter stator-rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes as claimed in claim 5, wherein the rotor core comprises square magnetic steel, pole shoes, a rotor yoke and T-shaped wedges, grooves are formed in the pole shoes and the rotor yoke respectively, the pole shoes and the rotor yoke are connected in an embedded mode through the square magnetic steel, wedge grooves used for inserting the rotor yoke of the T-shaped wedges are formed in the two sides of the groove for installing the magnetic steel in the rotor yoke, when the T-shaped wedges are inserted into the wedge grooves of the rotor yoke along the axial direction, the square magnetic steel, the pole shoes and the rotor yoke can be connected in an embedded mode to form a firm rotor core which is integrally connected in an embedded mode, and anaerobic glue or epoxy glue is applied to each connection portion.
9. The large-diameter stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes as claimed in any one of claims 1-8, wherein the stator core is formed by assembling Z identical pole slots, the Z identical stator pole slots are assembled through inner circle or outer circle positioning, and the Z identical stator pole slots have identical eccentricity.
CN202210338491.5A 2022-04-01 2022-04-01 Large-diameter stator and rotor double-eccentric non-uniform air gap three-phase permanent magnet servo motor with pole shoes Pending CN114629322A (en)

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