CN102088237B - Trapezoid coil-type permanent-magnetic coreless linear motor - Google Patents

Abstract

The trapezoidal coil type permanent magnet ironless linear motor includes a stator base, a stator winding, a mover base, and a Halbach permanent magnet array. The mover is located directly above the stator with an air gap. The stator winding is wound on the stator base. The stator winding is composed of trapezoidal coils interconnected. The Halbach permanent magnet array is installed, and the stator base and mover base are made of aluminum alloy. After the trapezoidal coil is used to replace the thin-layer coil of the existing Halbach permanent magnet iron-free linear motor, the 5th and 9th pulse power generated by the motor can be greatly reduced when the thin-layer coil is used, thereby improving the output smoothness of the motor. It has broad application prospects in ultra-high precision servo fields such as processing industry.

Description

Trapezoidal Coil Type Permanent Magnet Ironless Linear Motor

technical field

The invention is a permanent magnet ironless linear motor that can be applied to the high-precision servo field, and particularly relates to a permanent magnet ironless linear motor using a trapezoidal coil.

Background technique

The direct drive of the linear motor does not have the backlash of the transmission mechanism, uncertain ball movement, dust, lubrication and other problems that affect the positioning accuracy, there is no additional mass of the transmission mechanism, and the response is faster. Similar to rotary motors, linear motors are mainly divided into three categories: variable reluctance type, permanent magnet synchronous type, and induction type. Among them, the permanent magnet synchronous type has obvious advantages in structural design and control accuracy. The permanent magnet ironless linear motor involved in the present invention refers to a permanent magnet synchronous linear motor with the following characteristics: the permanent magnet array has no back iron, and the winding core is made of non-ferromagnetic materials. Although the output density of the permanent magnet ironless linear motor is lower than that of the iron motor, it completely eliminates the magnetic attraction and cogging force of the permanent magnet on the stator core, thereby further improving the high-precision positioning capability, its positioning accuracy and repeat positioning accuracy It can reach sub-micron level or even nanometer level, and has broad application prospects in ultra-high-precision servo fields such as semiconductor processing industry.

According to Maxwell's stress tensor method, it can be known that in ironless linear motors, the nth harmonic component of force exists only when both the permanent magnet array and the nth harmonic component of the winding magnetic field exist, and the amplitude of this component of force The value is proportional to the magnitude of this subcomponent of the magnetic field. It can be seen that if you want to eliminate the high-order pulsation force, you should eliminate the high-order harmonic components of the magnetic field generated by the permanent magnet array and winding as much as possible.

The magnetic field of the Halbach permanent magnet array is unilateral, which can generate a large magnetic field without a back iron, and the magnetic field on the strong side has excellent sinusoidal performance, and only contains fundamental waves, 5th and 9th harmonics Wave component, the above characteristics make Halbach permanent magnet arrays widely used in the field of ironless linear motors. The existing Halbeck permanent magnet ironless linear motors mostly use thin-layer coil windings, and the cross-section of the thin-layer coil element side is rectangular (in a rotating electrical machine, the element side refers to the part where the coil is placed in the slot; In the iron linear motor, the component side refers to the part where the coil generates effective electromagnetic force), which has the characteristics of easy mold processing and simple installation. The magnetic field generated by this coil contains fundamental, 5th, 9th and other harmonic components. To sum up, if the Halbach permanent magnet array and thin-layer coil structure are used, the ironless linear motor contains 5th and 9th order pulse force components.

Contents of the invention

Technical problem: The present invention provides an iron-free linear motor using a trapezoidal coil and a Halbach permanent magnet array. The linear motor has the characteristics of extremely small high-order pulse force.

Technical solution: The trapezoidal coil type permanent magnet ironless linear motor of the present invention includes a stator base, a stator winding, a mover base, and a Halbach permanent magnet array. The mover is located directly above the stator with an air gap, and the stator winding is wound on the stator base. The stator winding is composed of trapezoidal coils interconnected. The Halbach permanent magnet array is mounted on the surface, and the stator base and mover base are made of aluminum alloy.

The stator base is composed of the first coil core, the second coil core, the third coil core and the fourth coil core from left to right in one cycle; the stator winding is composed of the first trapezoidal coil to the eighth coil core in one cycle. Composed of trapezoidal coils, the first trapezoidal coil is set on the upper and lower sides of the first coil core, the second trapezoidal coil is set on the left and right sides of the second coil core, and the third trapezoidal coil is set on the upper and lower sides of the third coil core , the fourth trapezoidal coil is set on the left and right sides of the fourth coil core, the fifth trapezoidal coil is set on the left and right sides of the first coil core, the sixth trapezoidal coil is set on the upper and lower sides of the second coil core, and the seventh trapezoidal coil Set on the left and right sides of the third coil core, and the eighth trapezoidal coil on the upper and lower sides of the fourth coil core; the first trapezoidal coil, the second trapezoidal coil, the third trapezoidal coil, and the fourth trapezoidal coil are interconnected to form A phase The stator winding, wherein the upper side element side of the first trapezoidal coil is interconnected with the right side element side of the second trapezoidal coil, the left side element side of the second trapezoidal coil is interconnected with the upper side element side of the third trapezoidal coil, and the third The lower side element side of the trapezoidal coil is interconnected with the left side element side of the fourth trapezoidal coil, and the right side element side of the fourth trapezoidal coil is interconnected with the lower side element side of the first trapezoidal coil of the next period; the fifth trapezoidal coil , the sixth trapezoidal coil, the seventh trapezoidal coil, and the eighth trapezoidal coil are interconnected to form the B-phase stator winding, wherein the right element side of the fifth trapezoidal coil is interconnected with the lower side element side of the sixth trapezoidal coil, and the sixth trapezoidal coil The upper side element side of the seventh trapezoidal coil is interconnected with the right side element side of the seventh trapezoidal coil, the left side element side of the seventh trapezoidal coil is interconnected with the upper side element side of the eighth trapezoidal coil, and the lower side element side of the eighth trapezoidal coil is connected with The left element side of the fifth ladder coil of the next cycle is interconnected. The phase of the current passing through the A-phase stator winding is 90 degrees ahead of the current passing through the B-phase stator winding, which is used to form the stator traveling wave magnetic field.

Beneficial effect: compared with the prior art, the present invention has the following advantages:

According to Maxwell's stress tensor method, it can be known that in ironless linear motors, the nth harmonic component of force exists only when both the permanent magnet array and the nth harmonic component of the winding magnetic field exist, and the amplitude of this component of force The value is proportional to the magnitude of this subcomponent of the magnetic field. It can be seen that if you want to eliminate the high-order pulsation force, you should eliminate the high-order harmonic components of the magnetic field generated by the permanent magnet array and winding as much as possible.

Existing Halbach permanent magnet ironless linear motors mostly use windings composed of thin-layer coils. Among them, the strong side magnetic field of Halbach permanent magnet array contains harmonic components such as fundamental wave, 5th order, and 9th order. The section of the coil is rectangular, and the magnetic field generated by this coil contains fundamental, 5th, 9th and other harmonic components. It can be seen that if the ironless linear motor adopts Halbach permanent magnet array and thin-layer coil structure, the motor contains 5th and 9th order pulse force components.

A new winding structure composed of trapezoidal coils was proposed and applied to Halbach ironless linear motors. Analysis and simulation show that the magnetic field generated by the trapezoidal coil winding is extremely sinusoidal, and the high-order harmonics can be almost completely ignored, which can greatly reduce the 5th and 9th pulsation forces generated by thin-layer coils. The invention has broad application prospects in ultra-high-precision servo fields such as the semiconductor processing industry.

Description of drawings

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

Figure 2 is the thin-layer coil winding structure adopted by the existing Halbach permanent magnet ironless linear motor, in which Figure 2a is a 2-phase thin-layer coil winding structure, and Figure 2b is a 3-phase thin-layer coil winding structure.

Fig. 3 is a structural schematic diagram of the stator winding of the present invention.

Fig. 4 is a relationship diagram between the topological structure of the trapezoidal coil and the ratio of the fundamental wave of the winding magnetic field in the present invention.

Fig. 5 is the magnetic field harmonic analysis result of the present invention, wherein, Fig. 5 a is the magnetic field harmonic analysis result of Halbach permanent magnet array, Fig. 5 b is the magnetic field harmonic analysis result of trapezoidal coil type 2-phase winding, Fig. 5 c is volume and The magnetic field harmonic analysis results of the thin-layer coil type 2-phase winding with the same volume as the trapezoidal coil type winding, Fig. 5d is the magnetic field harmonic analysis result of the thin-layer coil type 3-phase winding with the same volume as the trapezoidal coil type winding.

The main symbols in the drawings are: stator base 1, stator winding 2, mover base 3, Halbach permanent magnet array 4, first coil core 11 to fourth coil core 14, first trapezoidal coil 21 to eighth trapezoidal coil 28. The length L of one cycle of the linear motor, the length h _c of the half-coil core, and the thickness of the winding layer are H _c .

1 Stator base 11～14 The first coil core to the fourth coil core 2 stator winding 21～28 The first trapezoidal coil to the eighth trapezoidal coil 3 mover matrix 4 Halbach permanent magnet array L The length of one cycle of a linear motor h _c Winding Layer Thickness h _c half core length the the

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings.

Referring to FIG. 1 , a trapezoidal coil type permanent magnet ironless linear motor includes a stator base 1 , a stator winding 2 , a mover base 3 , and a Halbach permanent magnet array 4 . The mover is located directly above the stator with an air gap left. The stator winding 2 is wound on the stator base 1. The stator winding 2 is formed by interconnecting trapezoidal coils. The Halbach permanent magnet array 4 is installed on the lower surface of the sub-base 3 , and the stator base 1 and the mover base 3 are made of aluminum alloy. The "arrow" in the Halbach permanent magnet array 4 represents the magnetization direction of the permanent magnet; the "dot" symbol in the stator winding 2 represents the current direction is the positive x-axis direction, and the "cross" symbol represents the current direction is the negative x-axis direction.

In addition, the edge effect of the motor can be reduced by the following measures: the depth of the permanent magnet array (the x-axis direction in Figure 1) is designed to be smaller than the depth of the winding current layer, and the permanent magnet array is designed in the x-axis direction The array is placed in the center of the current layer of the winding; by cutting off the coil that produces the edge effect (that is, the coil located at the edge of the permanent magnet array in the y-axis direction does not pass current). Research literature involving edge effects includes "Magnetically levitated planar actuator with moving magnets: Electromechanical analysis and design".

Referring to Figure 2, the existing Halbach permanent magnet ironless linear motors mostly use windings composed of thin-layer coils, and the cross-section of the side of the thin-layer coil elements is rectangular, where A and A' are the thin layers used to form the A-phase winding The two element sides of the coil, B and B' are the two element sides of the thin-layer coil used to form the B-phase winding, and C and C' are the two element sides of the thin-layer coil used to form the C-phase winding. Thin coils feature easy mold processing and simple installation. Research literature involving thin-layer coils includes "Comparison of Two Types of PM Linear Synchronous Servo and Miniature Motor With Air-Cored Film Coil" and "Analytical Force Calculations for High-Precision Planar Actuator With Halbach Magnet Array".

Referring to Fig. 3, the stator base 1 of the present invention is composed of a first coil core 11, a second coil core 12, a third coil core 13, and a fourth coil core 14 from left to right in one cycle; the stator winding 2 is formed in a The cycle is composed of the first trapezoidal coil 21 to the eighth trapezoidal coil 28, wherein the first trapezoidal coil 21 is set on the upper and lower sides of the first coil core 11, and the second trapezoidal coil 22 is set on the left and right sides of the second coil core 12. side, the third trapezoidal coil 23 is set on the upper and lower sides of the third coil core 13, the fourth trapezoidal coil 24 is set on the left and right sides of the fourth coil core 14, and the fifth trapezoidal coil 25 is set on the left and right sides of the first coil core 11 On both sides, the sixth trapezoidal coil 26 is set on the upper and lower sides of the second coil core 12, the seventh trapezoidal coil 27 is set on the left and right sides of the third coil core 13, and the eighth trapezoidal coil 28 is set on the fourth coil core 14. The upper and lower sides; the first trapezoidal coil 21, the second trapezoidal coil 22, the third trapezoidal coil 23, and the fourth trapezoidal coil 24 are interconnected to form the A-phase stator winding, wherein the upper side of the first trapezoidal coil 21 is connected to the second trapezoidal coil The right element side of the coil 22 is interconnected, the left element side of the second trapezoidal coil 22 is interconnected with the upper element side of the third trapezoidal coil 23, and the lower element side of the third trapezoidal coil 23 is connected with the fourth trapezoidal coil 24 The left side element side of the fourth trapezoidal coil 24 is interconnected with the lower side element side of the first trapezoidal coil 21 of the next cycle; the fifth trapezoidal coil 25, the sixth trapezoidal coil 26, the seventh trapezoidal coil The trapezoidal coil 27 and the eighth trapezoidal coil 28 are interconnected to form the B-phase stator winding, wherein the right element side of the fifth trapezoidal coil 25 is interconnected with the lower element side of the sixth trapezoidal coil 26, and the upper side of the sixth trapezoidal coil 26 The element side is interconnected with the right side element side of the seventh trapezoidal coil 27, the left side element side of the seventh trapezoidal coil 27 is interconnected with the upper side element side of the eighth trapezoidal coil 28, and the lower side element side of the eighth trapezoidal coil 28 It is interconnected with the left element side of the fifth trapezoidal coil 25 of the next cycle. The phase of the current passing through the A-phase stator winding is 90 degrees ahead of the current passing through the B-phase stator winding, which is used to form the stator traveling wave magnetic field.

Referring to Fig. 4, the trapezoidal coil winding of the present invention can generate an air-gap magnetic field with excellent sine, and high harmonics can be almost completely ignored, thereby greatly reducing the 5th and 9th pulsation forces generated by thin-layer coils. For example, when the length of the long base of the trapezoidal coil is equal to 0.25 times the length L of a pair of magnetic poles of the linear motor (that is, the length of one cycle of the linear motor), the thickness of the winding layer H _c is close to 0.25 times the length L of a pair of magnetic poles of the linear motor, half the coil When the core length h _c is close to 0, the fundamental wave ratio is as high as 99.9%. The electromagnetic field professional simulation software Ansys is used to model and obtain the calculation results, and then the professional mathematical tool Matlab is used to conduct harmonic analysis on the calculation results, and finally the analysis results shown in Figure 4 are obtained.

See Figure 5, a trapezoidal coil type permanent magnet ironless linear motor. The strong side magnetic field of the Halbach permanent magnet array contains fundamental, 5th, and 9th harmonic components, and the magnetic field generated by the thin-layer coil type 2-phase winding contains Fundamental wave, 3rd, 5th, 7th, 9th and other harmonic components, the magnetic field generated by thin-layer coil type 3-phase winding includes fundamental wave, 5th, 7th, 11th and other harmonic components. According to Maxwell's stress tensor method and the analysis results in Figure 5, it can be seen that the use of trapezoidal coils to replace the thin-layer coils of the existing Halbach permanent magnet ironless linear motor can greatly reduce the 5th and 9th pulsation forces generated by the motor when thin-layer coils are used , thereby improving the high-precision positioning capability of the motor.

The main parameters of the prototype used in the calculation include: the length of one cycle of the linear motor L = 25.4mm, the height of the permanent magnet = 6.35mm, the depth of the permanent magnet = 91mm, the residual magnetism of the permanent magnet = 1.3T, the relative permeability = 1, the maximum current of the coil Density = 1.5 ′ 10 ⁶ A′m ^-2 , winding layer thickness H _c =6.35mm, half coil core length h _c =0mm. The electromagnetic field professional simulation software Ansys is used to model and obtain the calculation results, and then the professional mathematical tool Matlab is used to conduct harmonic analysis on the calculation results, and finally the magnetic field harmonic analysis results shown in Figure 5 are obtained.

In addition, it can be seen from Figure 5 that the fundamental magnetic field generated by the trapezoidal coil winding is only about 50% of that of the thin-layer coil winding of the same volume. According to the Maxwell stress tensor method, the fundamental wave component of the electromagnetic force of the trapezoidal coil motor is also Only about 50% of the thin-layer coil type motor with the same volume, that is to say, the trapezoidal coil type linear motor is especially suitable for some high-precision servo fields that do not require high force-energy density but require high force smoothness. For example, the semiconductor processing industry, etc.

Claims (1)

1. A trapezoidal coil type permanent magnet ironless linear motor, characterized in that the motor includes a stator base (1), a stator winding (2), a mover base (3), a Halbach permanent magnet array (4); the mover Located directly above the stator with an air gap, the stator winding (2) is wound on the stator base (1). The stator winding (2) is composed of multiple trapezoidal coils interconnected. Trapezoidal coil, the Halbach permanent magnet array (4) is installed on the lower surface of the mover base (3), the stator base (1) and the mover base (3) are made of aluminum alloy; The stator base (1) is composed of a first coil core (11), a second coil core (12), a third coil core (13) and a fourth coil core (14) from left to right in one cycle ; The stator winding (2) is composed of the first trapezoidal coil (21) to the eighth trapezoidal coil (28) in one cycle, wherein the first trapezoidal coil (21) is set on the upper and lower sides of the first coil core (11) , the second trapezoidal coil (22) is set on the left and right sides of the second coil core (12), the third trapezoidal coil (23) is set on the upper and lower sides of the third coil core (13), the fourth trapezoidal coil (24) Set on the left and right sides of the fourth coil core (14), the fifth trapezoidal coil (25) is set on the left and right sides of the first coil core (11), and the sixth trapezoidal coil (26) is set on the second coil core (12 ), the seventh trapezoidal coil (27) is set on the left and right sides of the third coil core (13), and the eighth trapezoidal coil (28) is set on the upper and lower sides of the fourth coil core (14); the first The trapezoidal coil (21), the second trapezoidal coil (22), the third trapezoidal coil (23), and the fourth trapezoidal coil (24) are interconnected to form the A-phase stator winding, that is, the upper element side of the first trapezoidal coil (21) It is interconnected with the right element side of the second trapezoidal coil (22), the left element side of the second trapezoidal coil (22) is interconnected with the upper element side of the third trapezoidal coil (23), and the third trapezoidal coil (23) ) is interconnected with the left element side of the fourth trapezoidal coil (24), and the right element side of the fourth trapezoidal coil (24) is connected with the lower side element of the first trapezoidal coil (21) in the next cycle The sides are interconnected; the fifth trapezoidal coil (25), the sixth trapezoidal coil (26), the seventh trapezoidal coil (27), and the eighth trapezoidal coil (28) are interconnected to form the B-phase stator winding, wherein the fifth trapezoidal coil (25 ) is interconnected with the lower element side of the sixth trapezoidal coil (26), and the upper element side of the sixth trapezoidal coil (26) is interconnected with the right element side of the seventh trapezoidal coil (27), The left element side of the seventh trapezoidal coil (27) is interconnected with the upper element side of the eighth trapezoidal coil (28), and the lower element side of the eighth trapezoidal coil (28) is interconnected with the fifth trapezoidal coil ( 25) The left component side is interconnected.

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