WO2023145014A1

WO2023145014A1 - Linear motor

Info

Publication number: WO2023145014A1
Application number: PCT/JP2022/003386
Authority: WO
Inventors: ザイニアリフ; 優 ▲高▼村; 陽介高石; 慧大平野; 功太郎榊原; 健太郎橋本
Original assignee: 三菱電機株式会社
Priority date: 2022-01-28
Filing date: 2022-01-28
Publication date: 2023-08-03
Also published as: JPWO2023145014A1

Abstract

A linear motor (1) comprises: a field magnetic pole (2) having a plurality of permanent magnets (5), each of which is arranged at equal intervals; and an armature (3) that faces the field magnetic pole (2), moves relative to the field magnetic pole (2), and has an armature core (6), which has a plurality of teeth (9), and a coil (7), which is wound around each of two or more teeth (9) among the plurality of teeth (9). In the combination of the number of teeth (9) of the armature core (6) and the number of magnetic poles facing the plurality of teeth (9) and arranged in the direction of travel of the armature (3), the number of magnetic poles within the range of the width of the armature core (6) in the direction of travel is a non-integer.

Description

linear motor

The present disclosure relates to a linear motor having multiple permanent magnets.

A linear motor is known that includes a field magnetic pole having a plurality of permanent magnets and an armature that faces the field magnetic pole and moves in a linear direction with respect to the field magnetic pole. The armature has an armature core having a plurality of teeth and coils wound around the teeth, and generates magnetic flux when current flows through the coils. A thrust force that moves the armature in a straight line due to the interaction between the coil and the permanent magnet, that is, the attraction and repulsion generated between the coil and the permanent magnet according to the positional relationship between the magnetic flux and the permanent magnet. occurs.

A linear motor may generate cogging thrust, which is a pulsating thrust that accompanies the movement of the armature. One of the factors of the cogging thrust is that the attractive force generated between the end of the armature core in the moving direction of the armature and the field magnetic pole is affected by the positional relationship between the end of the armature core and the permanent magnet. It may change periodically due to

Patent Document 1 discloses a linear motor in which cogging thrust is reduced by forming teeth positioned at both ends of an armature core into a shape in which a part of the tip of each tooth is obliquely cut. disclosed. According to Patent Document 1, the width of the tip of each tooth positioned at both ends of the armature core is smaller than the width of the tip of the other teeth of the armature core, thereby reducing the width of the tip of the armature core. The phases of attraction forces generated in each cancel each other out. This makes it possible to reduce the cogging thrust of the entire armature.

JP-A-2003-299342

In the technique disclosed in Patent Document 1, each tooth positioned at both end portions of the armature core has a shape in which a part of the tip portion is cut obliquely. In comparison, the area of the surface of the teeth facing the permanent magnet is smaller. As a result, the magnetic resistance between the teeth positioned at both ends of the armature core and the permanent magnets increases, and the thrust density of the linear motor decreases. Therefore, according to the technique of Patent Document 1, there is a problem that it is difficult to reduce the cogging thrust while maintaining the thrust for driving the linear motor.

The present disclosure has been made in view of the above, and an object thereof is to obtain a linear motor capable of reducing cogging thrust while maintaining thrust for driving the linear motor.

In order to solve the above-described problems and achieve an object, a linear motor according to the present disclosure includes field magnetic poles each having a plurality of permanent magnets arranged at regular intervals, and an armature core having a plurality of teeth. , a coil wound around each of two or more teeth out of the plurality of teeth, and an armature that faces the field magnetic pole and moves relative to the field magnetic pole. Within the range of the width of the armature core in the direction of travel, the combination of the number of teeth possessed by the armature core and the number of magnetic poles facing the plurality of teeth and arranged in the direction of travel of the armature A given number of magnetic poles is a non-integer number.

The linear motor according to the present disclosure has the effect of reducing the cogging thrust while maintaining the thrust for driving the linear motor.

Schematic diagram of a linear motor according to the first embodiment FIG. 4 is a diagram showing a first example in which the armature core of the linear motor according to the first embodiment is composed of split cores; FIG. 4 shows a second example in which the armature core of the linear motor according to the first embodiment is composed of split cores; Schematic diagram showing a modification of the linear motor according to the first embodiment FIG. 1 is a first diagram for explaining the cogging thrust reduction effect in the linear motor according to the first embodiment; FIG. 2 is a second diagram for explaining the effect of reducing the cogging thrust in the linear motor according to the first embodiment; FIG. 3 is a third diagram for explaining the effect of reducing the cogging thrust in the linear motor according to the first embodiment; FIG. 5 is a diagram for explaining an example of the relationship between the cogging thrust and the number of magnetic poles in the basic combination in the linear motor according to the first embodiment; FIG. 1 is a first diagram for explaining the thrust and thrust ripple in the linear motor according to the first embodiment; FIG. 2 is a second diagram for explaining the thrust and thrust ripple in the linear motor according to the first embodiment; FIG. 4 is a diagram for explaining adjustment of the number of turns in the linear motor according to the first embodiment; Schematic diagram of a linear motor according to a second embodiment FIG. 5 is a diagram for explaining the effect of reducing cogging thrust in the linear motor according to the second embodiment; Schematic diagram of a linear motor according to a third embodiment FIG. 11 is a diagram for explaining the effect of reducing cogging thrust in the linear motor according to the third embodiment; Schematic diagram of a linear motor according to a modification of the third embodiment Schematic diagram of a linear motor according to a fourth embodiment

The linear motor according to the embodiment will be described in detail below based on the drawings.

Embodiment 1.
FIG. 1 is a schematic diagram of a linear motor 1 according to the first embodiment. The X-axis and the Y-axis are two axes perpendicular to each other. In the following description, the direction of the X axis is called the X direction, and the direction of the Y axis is called the Y direction.

A linear motor 1 has a field magnetic pole 2 as a stator and an armature 3 as a mover. The X direction is the traveling direction of the armature 3 with respect to the field magnetic poles 2 . The width of the armature 3 in the X direction is shorter than the width of the field pole 2 in the X direction. The armature 3 is arranged to face the field magnetic poles 2 . The field pole 2 and the armature 3 face each other with a gap in the Y direction. The armature 3 moves relatively to the field magnetic pole 2 by the thrust generated by interaction with the field magnetic pole 2 .

The field pole 2 has a back yoke 4 and a plurality of permanent magnets 5 arranged on the back yoke 4 in the X direction. The back yoke 4 is made of magnetic material. Each permanent magnet 5 is arranged at regular intervals in the X direction. The plurality of permanent magnets 5 are arranged so that N poles and S poles are alternately arranged in the X direction. That is, magnetic poles with different polarities are alternately arranged in the X direction.

The armature 3 has an armature core 6 and a plurality of coils 7. The armature core 6 has a core back 8 extending in the X direction and a plurality of teeth 9 arranged in the X direction. Each tooth 9 is made of a magnetic material. Each tooth 9 extends from the core back 8 toward the field pole 2 . Each tooth 9 is magnetically connected to each other by the core back 8 . Each tooth 9 is arranged at regular intervals in the X direction. A gap between teeth 9 adjacent to each other in the X direction is called a slot. Each coil 7 of the armature 3 is a concentrated winding coil formed for each tooth 9 .

The linear motor 1 is a three-phase motor driven by application of a three-phase AC voltage. The armature 3 shown in FIG. 1 has three teeth 9 . In the armature 3 , one coil 7 is wound around one tooth 9 . In Embodiment 1, a tooth number is assigned to each tooth 9 of the armature 3 for convenience. Each tooth 9 is assigned a tooth number t1, t2, t3 from left to right in FIG. A U-phase coil 7 is wound around the teeth 9 of t1. A V-phase coil 7 is wound around the tooth 9 at t2. A W-phase coil 7 is wound around the teeth 9 of t3. Each of the teeth 9 around which the coil 7 is wound has the same shape as each other. That is, in the armature 3 shown in FIG. 1, the teeth 9 of t1, t2, and t3 have the same shape.

The wire diameters of all the coils 7 included in the armature 3 are the same. That is, all the coils 7 of the armature 3 are made of conductor wires having the same diameter. As a result, the time required to manufacture the armature 3 can be shortened, and the productivity of the armature 3 can be improved, compared to the case where the coils 7 for each phase must be formed using conductive wires having different diameters. can be done.

A voltage is applied to the armature 3 from a three-phase AC power supply. Illustration of the three-phase AC power supply is omitted. The armature 3 generates magnetic flux when current flows through each coil 7 . An attractive force and a repulsive force are generated between the coils 7 and the permanent magnets 5 according to the positional relationship between the magnetic flux and the permanent magnets 5, thereby generating a thrust that moves the armature 3 in the X direction. The linear motor 1 moves the armature 3 in the X direction by generating thrust.

Here, the combination of the number of magnetic poles and the number of teeth 9 will be explained. The number of magnetic poles in the combination is the number of magnetic poles within the width Tw of the armature core 6 in the X direction. The width Tw is the X-direction width of the plurality of teeth 9 of the armature core 6 and is obtained by multiplying the pitch p of the teeth 9 by the number of teeth 9 . The pitch p is the distance between the center lines of teeth 9 adjacent to each other in the X direction. A center line of the tooth 9 represents the center of the tooth 9 in the X direction. In FIG. 1, the center line of each tooth 9 is represented by a one-dot chain line. A combination of the number of magnetic poles and the number of teeth 9 is hereinafter referred to as a basic combination. A basic combination is a combination of the number of teeth 9 that the armature core 6 has and the number of magnetic poles within the width Tw. The basic combination can also be said to be a combination of the number of teeth 9 that the armature core 6 has and the number of magnetic poles that face the plurality of teeth 9 and are arranged in the X direction.

In the basic combination of the linear motor 1, the number of teeth 9 and the number of magnetic poles are not integral multiples of each other. That is, the number of teeth 9 is not an integral multiple of the number of magnetic poles, and the number of magnetic poles is not an integral multiple of the number of teeth 9 . Further, the linear motor 1 is characterized in that the number of magnetic poles within the range of the width Tw of the armature core 6 is a decimal number, that is, a non-integer number in the basic combination.

In the linear motor 1 according to Embodiment 1, the number of teeth 9 is 3 and the number of magnetic poles is 2.5 in the basic combination. Hereinafter, a basic combination in which the number of teeth 9 is 3 and the number of magnetic poles is 2.5 will be referred to as "2.5 poles 3 teeth".

When the result of calculating the following formula (1) is a non-integer, that is, a decimal number, there is a relation that the number of teeth 9 is an integer number and the number of magnetic poles is a decimal number in the basic combination. For the linear motor 1, the result of calculating the equation (1) is a non-integer.
{L×Nt/(Nt−1)}÷τp (1)

Note that Nt is the number of teeth 9 around which the coil 7 is wound among the plurality of teeth 9 of the armature 3 . Let L be the distance between the teeth 9 at both ends in the X direction of the teeth 9 around which the coil 7 is wound. In the linear motor 1 shown in FIG. 1, L is the distance between the center line of the teeth 9 at t1 and the center line of the teeth 9 at t3. τp is the pitch of the magnetic poles. The pitch of the magnetic poles is the distance between the center positions of magnetic poles of different polarities that are adjacent to each other in the X direction. In the example shown in FIG. 1, Nt is three. Also, for example, L is 32 [mm] and τp is 19.2 [mm]. In this case, the result of calculating the equation (1) is 2.5, and the relationship holds that the number of teeth 9 in the basic combination is an integer while the number of magnetic poles is a decimal number.

In the linear motor 1, the number of teeth 9 is an integer in the basic combination, whereas the number of magnetic poles is a non-integer. , the cogging thrust can be reduced. Effects of the configuration of the linear motor 1 according to the first embodiment will be described later.

The armature core 6 is made of a magnetic material. The armature core 6 shown in FIG. 1 is manufactured as an integral body by press working or the like. The armature core 6 may be a combination of a plurality of split cores manufactured by press working or the like. When it is difficult to manufacture the armature core 6 as an integral body due to circumstances such as the production equipment, the size of the linear motor 1, and the specifications of the coil 7, it is possible to manufacture a plurality of split cores and combine the plurality of split cores. , the armature core 6 can be manufactured.

Here, an example in which the armature core 6 is composed of split cores will be described. FIG. 2 is a diagram showing a first example in which the armature core 6 of the linear motor 1 according to the first embodiment is composed of split cores. In the first example, the armature core 6 is a combination of three parts 6a having the same shape. Each component 6a is a split core. The armature core 6 is divided into three parts 6a by dividing the core back 8 between the teeth 9 adjacent to each other. Since each part 6a has the same shape as each other, each part 6a can be manufactured using the same press die.

FIG. 3 is a diagram showing a second example in which the armature core 6 of the linear motor 1 according to Embodiment 1 is composed of split cores. In a second example, each of the core back 8 and the three teeth 9 is manufactured as a split core. Armature core 6 is manufactured by combining core back 8 and three teeth 9 . Since each tooth 9 has the same shape, each tooth 9 can be manufactured using the same press die.

By configuring the armature core 6 with split cores as in the first example or the second example, it is possible to reduce the size of the press die and reduce the cost required for the production equipment. Forming the armature core 6 with split cores is suitable for mass production of the armature core 6, because press working can be facilitated by downsizing the press die. The armature core 6 or split cores may be manufactured by a method other than press working.

In Embodiment 1, the linear motor 1 is a three-phase motor, and one-phase coils 7 are attached to each of the three teeth 9, but the number of phases is not limited to three. The number of coils 7 provided in the armature 3 and the number of teeth 9 of the armature core 6 may be appropriately changed according to the number of phases. The linear motor 1 may have a coil 7 wound around each of two or more teeth 9 .

The armature core 6 may further have auxiliary teeth that are different from the plurality of teeth 9 . FIG. 4 is a schematic diagram showing a modification of the linear motor 1 according to the first embodiment. The armature core 6 of the linear motor 1 according to the modification has two auxiliary teeth 9a. One of the two auxiliary teeth 9a is provided at one end of the armature core 6 in the X direction. The other of the two auxiliary teeth 9a is provided at the other end of the armature core 6 in the X direction. The shape of each auxiliary tooth 9 a is different from the shape of each tooth 9 . The coil 7 is not wound around each auxiliary tooth 9a.

The linear motor 1 of this modified example has a basic combination of 2.5 poles and 3 teeth, as in the case shown in FIG. The linear motor 1 can further reduce cogging by adding the auxiliary teeth 9a. It is to be noted that it is optional whether or not the linear motor 1 is provided with the auxiliary teeth 9a.

Only permanent magnets 5 magnetized in the Y direction are used in the field poles 2 shown in FIG. The field poles 2 include not only the permanent magnets 5 magnetized in the Y direction, but also the permanent magnets 5 magnetized in the X direction, or the permanent magnets 5 magnetized in an oblique direction between the X and Y directions. 5 may be used. The field magnetic poles 2 may have a so-called magnetic flux concentration type structure in which magnetic flux is concentrated by having permanent magnets 5 magnetized in the X direction or oblique directions, or may have a Halbach array structure. The magnetic flux density of the field pole 2 can be increased by making the field pole 2 have a magnetic flux concentration type structure or a Halbach arrangement structure. By increasing the magnetic flux density of the field magnetic poles 2, the thrust density of the linear motor 1 can be increased. It is optional whether the field magnetic pole 2 has a magnetic flux concentration type structure or a Halbach array structure.

The linear motor 1 can increase the magnetic flux density of the field magnetic pole 2 and the thrust density by providing the back yoke 4 made of a magnetic material to the field magnetic pole 2 . It is assumed that whether or not the back yoke 4 is provided on the field pole 2 is optional.

Next, the effects of the configuration of the linear motor 1 according to Embodiment 1 will be described. In the linear motor 1 , the state of magnetic flux between the armature 3 and the field pole 2 is discontinuous at the X-direction end of the armature 3 . When the armature 3 moves with respect to the field magnetic pole 2, the attractive force generated between the permanent magnet 5 and the end of the armature 3 is caused by the positional relationship between the permanent magnet 5 and the end of the armature 3. changes cyclically. As a result, a cogging thrust is generated in the linear motor 1 by adding a pulsation component to the thrust that moves the armature 3 .

The linear motor 1 uses an armature 3 with a finite length. A cogging thrust caused by the edge of the , that is, a cogging thrust due to the so-called edge effect is generated. On the other hand, in the case of a rotary motor, since the armature does not have an edge where the state of magnetic flux between the armature and the magnetic field pole is discontinuous, cogging thrust due to the edge effect does not occur.

FIG. 5 is a first diagram for explaining the effect of reducing the cogging thrust in the linear motor 1 according to the first embodiment. FIG. 6 is a second diagram for explaining the cogging thrust reduction effect in the linear motor 1 according to the first embodiment.

5 and 6 show vector diagrams of cogging thrust in a motor having a basic combination of two poles and three teeth instead of the linear motor 1 according to the first embodiment. A basic combination of two poles and three teeth is a basic combination in which the number of teeth 9 is three and the number of magnetic poles is two. The teeth numbers t1, t2, and t3 are also assigned to the three teeth 9 of such a motor as in the case of the linear motor 1. FIG. In addition, in the case of the basic combination of two poles and three teeth, Nt is 3 in the above formula (1). Also, for example, L is 32 [mm] and τp is 24 [mm]. In this case, the result of calculating formula (1) is 2, and both the number of teeth 9 and the number of magnetic poles in the basic combination are integers.

FIG. 5 shows an example of a vector diagram for a case where no cogging thrust due to the end effect is generated, that is, for a rotary motor. FIG. 6 shows an example of a vector diagram of a linear motor that is a comparative example when cogging thrust is generated due to the end effect. 5 and 6, the vertical axis represents the cosine component of the vector, and the horizontal axis represents the sine component of the vector.

In FIG. 5, the thick line represents the secondary component vector of the cogging thrust generated in each of the three teeth 9 when the rotor is rotated at an electrical angle of 360 degrees. The secondary component is a frequency component that is twice the fundamental frequency, which is the rotation frequency of the rotor. The cogging thrust generated in each tooth 9 includes a secondary component and a higher-order component than the secondary component, but the secondary component will be focused here. An electrical angle of 360 degrees is defined as a section in which the field magnetic pole 2 generates a pair of magnetic flux density distributions of N and S poles. When one tooth 9 passes over the section of the N pole and the S pole, the tooth 9 receives magnetic attraction from each of the N pole and the S pole, thereby generating two thrust pulsations. Therefore, a secondary component, which is two pulsations, is generated in the section of 360 electrical degrees.

As shown in FIG. 5, the amplitude of the secondary component vector in each tooth 9 is the same, and the secondary component vector in each tooth 9 is distributed with a phase difference of 120 degrees. Therefore, no synthesized vector is generated by synthesizing the secondary component vectors in each tooth 9 . In this way, in the rotary motor described in FIG. 5, the cogging thrust generated in each tooth 9 is balanced with each other, so that the cogging thrust in the entire armature is reduced.

FIG. 6 shows secondary component vectors of cogging thrust generated in each of the three teeth 9 when the operation of the rotary motor in FIG. 5 is replaced by a linear motor. In FIG. 6 as well, the secondary component vector of the cogging thrust is represented by a thick line. The amplitude and phase of each secondary component vector shown in FIG. 6 change compared to the case shown in FIG. 5 due to end effects. Therefore, a synthesized vector is generated by synthesizing the secondary component vectors in each tooth 9 . The white arrows in FIG. 6 represent composite vectors. As described above, in the linear motor described with reference to FIG. 6, the cogging thrust generated in each tooth 9 is out of balance, and the cogging thrust in the entire armature increases.

In the linear motor 1 according to the first embodiment, in the basic combination, by setting the number of magnetic poles within the range of the width Tw of the armature core 6 to be a non-integer, the amplitude and phase of the cogging thrust generated in each tooth 9 are reduced to is changed from the state shown in FIG. The linear motor 1 reduces the cogging thrust in the entire armature 3 by changing the balance of the cogging thrust to reduce the resultant vector. Thereby, the linear motor 1 can reduce the cogging thrust compared to the case where the number of magnetic poles in the basic combination is an integer.

FIG. 7 is a third diagram for explaining the cogging thrust reduction effect in the linear motor 1 according to the first embodiment. FIG. 7 shows a graph showing changes in the cogging thrust in the 2.5-pole, 3-teeth linear motor 1 according to the first embodiment, and a graph showing changes in the cogging thrust in the 2-pole, 3-teeth linear motor of the comparative example. and In FIG. 7, the solid line represents the graph for the case of 2.5 poles and 3 teeth. The graph for 2-pole 3-teeth is represented by a broken line. In FIG. 7, the vertical axis represents the cogging thrust normalized based on the amplitude in the case of two poles and three teeth. In FIG. 7, the horizontal axis represents the electrical angle. The relationship between the cogging thrust and the electrical angle shown in FIG. 7 can be obtained by magnetic field analysis.

As shown in FIG. 7, the waveform in the case of two poles and three teeth has two peaks and two valleys in the electrical angle range of 360 degrees. That is, it can be seen that the secondary component of the cogging thrust is dominant in the two-pole, three-teeth linear motor. On the other hand, the waveform in the case of 2.5 poles and 3 teeth has 4 peaks and 4 valleys in the electrical angle range of 360 degrees. In the waveform in the case of 2.5 poles and 3 teeth, the secondary component of the cogging thrust that was dominant in the case of 2 poles and 3 teeth has almost disappeared. As a result, in the 2.5-pole, 3-teeth linear motor 1, the overall cogging thrust is reduced by about 70% compared to the 2-pole, 3-teeth linear motor. Thus, the linear motor 1 can significantly reduce the cogging thrust compared to the case of the comparative example.

FIG. 8 is a diagram for explaining an example of the relationship between the cogging thrust and the number of magnetic poles in the basic combination in the linear motor 1 according to the first embodiment. FIG. 8 is a line graph showing the relationship between the amplitude value of the cogging thrust and the number of magnetic poles in the basic combination when the number of magnetic poles in the basic combination is changed. In the relationship shown in FIG. 8, the number of magnetic poles in the basic combination is varied in the range of 2 to 2.9, while the number of teeth 9 in the basic combination remains 3. In FIG. 8, the vertical axis represents the amplitude value of the cogging thrust. The amplitude value represented by the vertical axis is the amplitude value normalized based on the amplitude value when the number of magnetic poles in the basic combination is two. In FIG. 8, the horizontal axis represents the number of magnetic poles in the basic combination. The relationship between the amplitude value and the number of magnetic poles shown in FIG. 8 can be obtained by magnetic field analysis.

In FIG. 8, when the number of magnetic poles is a value other than two, the amplitude is smaller than when the number of magnetic poles is two. That is, according to FIG. 8, when the number of magnetic poles is a non-integer greater than 2 and less than 2.9, the linear motor 1 can reduce the cogging thrust more than when the number of magnetic poles is 2. can. In this way, the linear motor 1 has an integer number of teeth 9 and a non-integer number of magnetic poles in the basic combination, so that the number of teeth 9 and the number of magnetic poles in the basic combination are both integers. , the cogging thrust can be reduced.

Also, in the example shown in FIG. 8, the amplitude value is the minimum when the number of magnetic poles is 2.5. That is, according to FIG. 8, the linear motor 1 can minimize the cogging thrust by setting the number of magnetic poles in the basic combination to 2.5. The optimal basic combination for minimizing the cogging thrust varies depending on the design of the magnetic structure of the linear motor 1, such as the shape or size of the teeth 9, the shape or size of the permanent magnets 5, and the like. The number of teeth 9 and the number of magnetic poles in the basic combination can be changed as appropriate according to the configuration of the linear motor 1 .

Next, countermeasures for a reduction in thrust that can occur in the linear motor 1 and an increase in thrust ripple that can occur when the linear motor 1 is energized will be described. FIG. 9 is a first diagram for explaining thrust and thrust ripple in the linear motor 1 according to the first embodiment. FIG. 10 is a second diagram for explaining thrust and thrust ripple in the linear motor 1 according to the first embodiment.

FIG. 9 shows an example of the phase induced voltage vector and the voltage vector of the control device when both the number of teeth 9 and the number of magnetic poles in the basic combination are integers. A control device is a device that controls the linear motor 1 . A voltage vector of the control device is a vector of voltages for driving the linear motor 1, and is a vector of voltages output from a three-phase power supply for driving the linear motor 1. FIG. FIG. 9 shows phase induced voltage vectors and voltage vectors in a 2-pole 3-teeth motor. FIG. 10 shows an example of the phase induced voltage vector and the voltage vector of the control device when the number of teeth 9 in the basic combination is an integer and the number of magnetic poles is a non-integer. FIG. 10 shows phase induced voltage vectors and voltage vectors in a 2.5-pole, 3-teeth motor. In FIGS. 9 and 10, arrows U, V, and W indicate voltage vectors of phases U, V, and W of the control equipment. Each thick line of the U-phase, V-phase, and W-phase indicates the phase induced voltage vector of each of the U-, V-, and W-phases.

In general, in a linear motor that is a concentrated winding motor, all the coils 7 of the linear motor have the same number of turns. In the examples shown in FIGS. 9 and 10, it is assumed that each coil 7 has the same number of turns. As shown in FIG. 9, when the number of teeth 9 and the number of magnetic poles in the basic combination are both integers and the number of turns of each coil 7 is the same, the phase induced voltage vector and the voltage vector matches. In this case, the amplitude of the current in each phase is the same.

On the other hand, as shown in FIG. 10, when the number of teeth 9 in the basic combination is an integer, the number of magnetic poles is a non-integer, and the number of turns of each coil 7 is the same, the number of turns shown in FIG. The phase of the phase induced voltage vector changes compared to the case. Therefore, in the example shown in FIG. 10, the phase of the phase induced voltage vector does not match the phase of the voltage vector. Since the phase of the phase induced voltage vector does not match the phase of the voltage vector, the amplitude of the projection component of the phase induced voltage vector onto the phase of the voltage vector differs for each phase. In this case, a difference in the amplitude of the current of each phase may cause a reduction in thrust and an increase in thrust ripple during energization.

The linear motor 1 according to the first embodiment may adjust the number of turns of the coil 7 for each phase as a countermeasure against the decrease in thrust force and the increase in thrust ripple. The number of turns of the coil 7 for each phase is adjusted so that the phase of the voltage for driving the linear motor 1, that is, the amplitude of the projection component of the phase induced voltage vector onto the phase of the voltage vector is the same for each phase. .

FIG. 11 is a diagram for explaining adjustment of the number of turns in the linear motor 1 according to the first embodiment. FIG. 11 shows the number of turns of the U-phase, V-phase and W-phase coils 7 and the U-phase, V-phase and W-phase drive shafts before and after the adjustment of the number of turns. Figure 3 shows an example with component amplitudes. The drive shaft component is a projected component of the phase induced voltage vector when the phase induced voltage vector is projected onto the phase of the voltage vector. The value of the number of turns in FIG. 11 is a value normalized based on the total number of turns of each coil 7, and is represented by a value up to three decimal places. The value representing the amplitude of the drive shaft component is a value normalized based on the total amplitude when the phase of the phase induced voltage vector matches the phase of the voltage vector for each of the U-phase, V-phase and W-phase. , expressed as a value up to three decimal places. Each value shown in FIG. 11 is for the linear motor 1, which is a 2.5-pole, 3-teeth motor.

Before the adjustment of the number of turns, the number of turns of each of the U-phase, V-phase and W-phase are equal to each other and all are 0.333. As shown in FIG. 10, in the 2.5-pole 3-teeth motor, the U-phase phase induced voltage vector is shifted from the U-phase voltage vector toward the W-phase voltage vector. Also, the phase induced voltage vector of the W phase is shifted from the voltage vector of the W phase toward the voltage vector of the U phase. In the 2.5-pole 3-teeth motor, the phase shift of the phase induced voltage vector from the phase of the voltage vector is calculated to be 30 degrees. By shifting the phase of the phase induced voltage vector from the phase of the voltage vector by 30 degrees, the amplitude of the drive shaft component in each of the U-phase and W-phase changes from 0.333 to 0.289 (≈0.333×cos30°). to

Since the amplitude of the drive shaft component in each of the U phase and the W phase is smaller than the amplitude of the drive shaft component in the V phase, the number of turns of the U phase and the number of turns of the W phase are each greater than the number of turns of the V phase. The adjustment to increase equalizes the amplitude of the drive shaft component in each phase. In the example shown in FIG. 11, the number of turns of the U phase and the number of turns of the W phase are each increased from 0.333 to 0.349, and the number of turns of the V phase is decreased from 0.333 to 0.302. adjustments are made. With this adjustment, the amplitude of the drive shaft component in each phase becomes 0.302. By adjusting the number of turns of the coil 7 of each phase in this manner, the amplitude of the drive shaft component in each phase can be equalized. By equalizing the amplitude of the drive shaft component in each phase, the linear motor 1 can reduce the decrease in thrust and the increase in thrust ripple.

According to the first embodiment, the linear motor 1 has an integer number of teeth 9 in the basic combination, whereas the number of magnetic poles is a non-integer number in the basic combination. Cogging thrust can be reduced compared to the case where it is an integer. The linear motor 1 can reduce the decrease in thrust density compared to the case where the tooth 9 is partially cut. As described above, the linear motor 1 has the effect of being able to reduce the cogging thrust while maintaining the thrust for driving the linear motor 1 .

Embodiment 2.
FIG. 12 is a schematic diagram of a linear motor 1A according to the second embodiment. The armature 3A of the linear motor 1A has teeth 9 around which the coils 7 are wound and teeth 9 around which the coils 7 are not wound. In the second embodiment, the same reference numerals are assigned to the same components as in the first embodiment, and the configuration different from the first embodiment will be mainly described.

The armature core 6A of the armature 3A has six teeth 9 arranged in the X direction. In Embodiment 2, a tooth number is assigned to each tooth 9 of the armature 3A for convenience. Each tooth 9 is assigned a tooth number t1, t2, t3, t4, t5 and t6 from left to right in FIG. A U-phase coil 7 is wound around the teeth 9 of t2. A V-phase coil 7 is wound around the teeth 9 of t4. A W-phase coil 7 is wound around the teeth 9 of t6. No coil 7 is wound around each tooth 9 at t1, t3, and t5. The number of turns of each tooth 9 at t2, t4 and t6 is greater than the number of turns of each tooth 9 in the first embodiment. Teeth 9 of t2, t4, and t6, which are teeth 9 around which coils 7 are wound, have the same shape.

Also in the second embodiment, as in the first embodiment, in the basic combination of the linear motor 1A, the number of teeth 9 and the number of magnetic poles are not integral multiples of each other. Further, the linear motor 1A is characterized in that the number of magnetic poles within the range of the width Tw of the armature core 6 is a decimal number, that is, a non-integer number in the basic combination. Also in the second embodiment, the result of calculating the above formula (1) is a non-integer. In the linear motor 1A shown in FIG. 12, L is the distance between the center line of the teeth 9 at t2 and the center line of the teeth 9 at t6. In the example shown in FIG. 12, Nt is 3 in the above formula (1). Also, for example, L is 64 [mm] and τp is 21.3333333 [mm]. In this case, the result of calculating the equation (1) is approximately 4.5, and the relationship holds that the number of teeth 9 in the basic combination is an integer while the number of magnetic poles is a decimal number.

In the linear motor 1A according to the second embodiment, the number of teeth 9 is 6 and the number of magnetic poles is 4.5 in the basic combination. Hereinafter, a basic combination in which the number of teeth 9 is 6 and the number of magnetic poles is 4.5 is expressed as "4.5 poles 6 teeth".

By having the teeth 9 wound with the coils 7 and the teeth 9 not wound with the coils 7, the number of the coils 7 in the armature 3A can be reduced compared to the case where the coils 7 are wound on all the teeth 9. can do. By reducing the number of coils 7 and the number of parts for installing the coils 7, the production cost of the linear motor 1A can be reduced. By reducing the number of coils 7, the number of operations for winding the coils 7 can be reduced. In addition, since the number of coils 7 can be reduced, work for connecting the coils 7 can be reduced. Thereby, the productivity of the linear motor 1A can be improved.

Since only one phase coil 7 is wound on each tooth 9 around which the coil 7 is wound, a component for insulating the coils 7 of different phases from each other is not required. The production cost of the linear motor 1A can be reduced by reducing the number of parts of the linear motor 1A.

FIG. 13 is a diagram for explaining the cogging thrust reduction effect in the linear motor 1A according to the second embodiment. FIG. 13 shows a graph showing changes in the cogging thrust in the 4.5-pole, 6-teeth linear motor 1A according to the second embodiment, and a graph showing changes in the cogging thrust in the 4-pole, 6-teeth linear motor of the comparative example. and The linear motor according to the comparative example also has three coils 7, like the linear motor 1A shown in FIG. In the case of the basic combination of 4 poles and 6 teeth as a comparative example, Nt in the above formula (1) is 3. Also, for example, L is 64 [mm] and τp is 24 [mm]. In this case, the result of calculating formula (1) is 4, and both the number of teeth 9 and the number of magnetic poles in the basic combination are integers.

In FIG. 13, the graph for 4.5 poles and 6 teeth is represented by a solid line. The graph for the case of 4 poles and 6 teeth is represented by a dashed line. In FIG. 13, the vertical axis represents the cogging thrust normalized based on the amplitude in the case of 4 poles and 6 teeth. In FIG. 13, the horizontal axis represents the electrical angle. The relationship between the cogging thrust and the electrical angle shown in FIG. 13 can be obtained by magnetic field analysis.

As shown in FIG. 13, the waveform in the case of 4 poles and 6 teeth has two peaks and two valleys in the electrical angle range of 360 degrees. That is, it can be seen that the secondary component of the cogging thrust is dominant in the 4-pole, 6-teeth linear motor. On the other hand, the waveform in the case of 4.5 poles and 6 teeth has 4 peaks and 4 valleys in the electrical angle range of 360 degrees. In the waveform in the case of 4.5 poles and 6 teeth, the secondary component of the cogging thrust that was dominant in the case of 4 poles and 6 teeth almost disappeared. As a result, in the 4.5-pole, 6-teeth linear motor 1, the overall cogging thrust is reduced by about 70% compared to the 4-pole, 6-teeth linear motor. Thus, the linear motor 1A can significantly reduce the cogging thrust compared to the case of the comparative example.

The optimum basic combination for minimizing the cogging thrust varies depending on the design of the magnetic structure of the linear motor 1A, such as the shape or size of the teeth 9, the shape or size of the permanent magnets 5, and the like. The number of teeth 9 and the number of magnetic poles in the basic combination can be appropriately changed according to the configuration of the linear motor 1A.

Also in the second embodiment, the linear motor 1A has the effect of reducing the cogging thrust while maintaining the thrust for driving the linear motor 1A, as in the first embodiment.

Embodiment 3.
FIG. 14 is a schematic diagram of a linear motor 1B according to the third embodiment. In

Embodiments

1 and 2, the number of teeth 9 of

armatures

3 and 3A is an integral multiple of the number of phases. Embodiment 3 describes a case where the number of teeth 9 of the armature 3B is not an integer multiple of the number of phases. In the third embodiment, the same reference numerals are assigned to the same constituent elements as in the first or second embodiment, and the configuration different from that in the first or second embodiment will be mainly described.

The armature core 6B of the armature 3B has five teeth 9 arranged in the X direction. In Embodiment 3, a tooth number is assigned to each tooth 9 of the armature 3B for convenience. Teeth numbers t1, t2, t3, t4 and t5 are assigned to the teeth 9 from left to right in FIG.

A U-phase coil 7 is wound around each of the teeth 9 at t1 and the teeth 9 at t5. A V-phase coil 7 is wound around the tooth 9 at t2. A V-phase coil 7 and a W-phase coil 7 are wound around the teeth 9 of t3. A W-phase coil 7 is wound around the teeth 9 of t4. In this way, the plurality of teeth 9 of the armature core 6B are composed of the teeth 9 wound with only one phase coil 7 out of three phases and the teeth 9 wound with two or more phase coils 7 out of three phases. including. The teeth 9 of t1, t2, t3, t4, and t5, which are the teeth 9 around which the coil 7 is wound, have the same shape.

Also in the third embodiment, as in the first embodiment, in the basic combination of the linear motor 1B, the number of magnetic poles and the number of teeth 9 are not integral multiples of each other. Further, the linear motor 1B is characterized in that the number of magnetic poles within the range of the width Tw of the armature core 6 is a decimal number, that is, a non-integer number in the basic combination. Also in the third embodiment, the result of calculating the above formula (1) is a non-integer. In the example shown in FIG. 14, Nt is five. Also, for example, L is 64 [mm] and τp is 20.5128205 [mm]. In this case, the result of calculating the equation (1) is approximately 3.9, and the relationship holds that the number of teeth 9 in the basic combination is an integer while the number of magnetic poles is a decimal number.

In the linear motor 1B according to Embodiment 3, the number of teeth 9 is 5 and the number of magnetic poles is 3.9 in the basic combination. Hereinafter, the basic combination in which the number of teeth 9 is 5 and the number of magnetic poles is 3.9 is expressed as "3.9 poles 5 teeth". The order of the phases of the coil 7 in the X direction is determined by the basic combination, the number of phases, the number of teeth 9 around which the coils 7 of a plurality of phases are wound, the number of the coils 7 wound around the teeth 9, and the like.

FIG. 15 is a diagram for explaining the cogging thrust reduction effect in the linear motor 1B according to the third embodiment. FIG. 15 shows a graph showing changes in the cogging thrust in the 3.9-pole, 5-teeth linear motor 1B according to the third embodiment, and a graph showing changes in the cogging thrust in the 4-pole, 5-teeth linear motor of the comparative example. and Similarly to the linear motor 1B shown in FIG. 14, the linear motor according to the comparative example also has teeth 9 wound with only one phase coil 7 out of three phases and coils 7 of a plurality of phases out of three phases wound. and teeth 9. In the case of the basic combination of 4 poles and 5 teeth, which is a comparative example, Nt is 5 in the above formula (1). Also, for example, L is 64 [mm] and τp is 20 [mm]. In this case, the result of calculating formula (1) is 4, and both the number of teeth 9 and the number of magnetic poles in the basic combination are integers.

In FIG. 15, the graph for the case of 3.9 poles and 5 teeth is represented by a solid line. The graph for 4 poles and 5 teeth is represented by a dashed line. In FIG. 15, the vertical axis represents the cogging thrust standardized based on the amplitude in the case of four poles and five teeth. In FIG. 15, the horizontal axis represents the electrical angle. The relationship between the cogging thrust and the electrical angle shown in FIG. 15 can be obtained by magnetic field analysis.

As shown in FIG. 15, the amplitude in the case of 3.9 poles and 5 teeth is smaller than the amplitude in the case of 4 poles and 5 teeth. From this, it can be seen that the secondary component of the cogging thrust is smaller in the linear motor 1B with 3.9 poles and 5 teeth than in the case of 4 poles and 5 teeth. In the 3.9-pole, 5-teeth linear motor 1B, the overall cogging thrust is reduced by about 60% compared to the 4-pole, 5-teeth linear motor 1B. Thus, the linear motor 1B can significantly reduce the cogging thrust compared to the case of the comparative example.

A linear motor 1B shown in FIG. 15 has one tooth 9 around which a plurality of phase coils 7 are wound, and each of the other teeth 9 is wound with only one phase coil 7 . The linear motor 1B may have a plurality of teeth 9 around which coils 7 of a plurality of phases are wound.

FIG. 16 is a schematic diagram of a linear motor 1C according to a modification of the third embodiment. In the armature 3C of the linear motor 1C, a U-phase coil 7 is wound around the teeth 9 of t1. A U-phase coil 7 and a V-phase coil 7 are wound around the teeth 9 of t2. A V-phase coil 7 is wound around the teeth 9 of t3. A V-phase coil 7 and a W-phase coil 7 are wound around the teeth 9 of t4. A W-phase coil 7 is wound around the teeth 9 of t5. Thus, in the linear motor 1C, each tooth 9 of t1, t3, t5 is wound with only one phase coil 7 out of three phases, and each tooth 9 of t2, t4 is wound with two phases of three phases. A phase coil 7 is wound.

By increasing the number of teeth 9 around which coils 7 of a plurality of phases are wound, adjustment for balancing the phase induced voltage vectors of each phase and adjustment for reducing the difference in phase inductance between the phases are facilitated. Become. As a result, the linear motor 1C can reduce the thrust ripple when energized.

In cases where the number of teeth 9 is not an integer multiple of the number of phases, the number of turns of each coil 7 is adjusted to balance the phase induced voltage vectors of each phase. Among the plurality of teeth 9, there are teeth 9 with a large number of turns of the coil 7 and teeth 9 with a small number of turns of the coil 7. Since there is a difference in the number of turns of the coil 7 for each tooth 9 and the wire diameter of all the coils 7 is the same, a space without the coil 7 is likely to occur in the slot. If the lamination factor of the coil 7 decreases due to the space, the copper loss of the

linear motors

1B and 1C increases.

The

linear motors

1B and 1C can adjust a basic combination in which the number of teeth 9 is an integer and the number of magnetic poles is a non-integer so that the total number of turns of the coil 7 entering each slot is evened out. In this case, the

linear motors

1B and 1C can reduce the cogging thrust due to the end effect and improve the space factor. As a result, the

linear motors

1B and 1C can reduce cogging thrust and copper loss.

The number of coils 7 provided in the

armatures

3B and 3C and the number of teeth 9 of the armature core 6B are arbitrary. The

linear motors

1B and 1C may have auxiliary teeth 9a like the linear motor 1 shown in FIG.

Linear motors

1B and 1C may have teeth 9 around which coils 7 are wound and teeth 9 around which coils 7 are not wound, like linear motor 1A according to the second embodiment.

The optimum basic combination for minimizing the cogging thrust varies depending on the magnetic structure design of the

linear motors

1B and 1C, such as the shape or size of the teeth 9 and the shape or size of the permanent magnets 5. The number of teeth 9 and the number of magnetic poles in the basic combination can be appropriately changed according to the configuration of the

linear motors

1B and 1C.

In the third embodiment, similarly to the first embodiment, the

linear motors

1B and 1C have the effect of reducing the cogging thrust while maintaining the thrust for driving the

linear motors

1B and 1C.

Embodiment 4.
FIG. 17 is a schematic diagram of a linear motor 1D according to the fourth embodiment. A linear motor 1</b>D has a tandem armature 11 . The tandem armature 11 has two armatures 3B that share the field poles 2. As shown in FIG. The two armatures 3B are arranged in the X direction. The tandem armature 11 is an example of an array armature composed of a plurality of armatures 3B. The linear motor 1D increases the thrust by tandem driving in which two armatures 3B are driven at the same time as compared with the case of driving one armature 3B. In the fourth embodiment, the same reference numerals are assigned to the same components as in the first to third embodiments, and the configuration different from the first to third embodiments will be mainly described.

In Embodiment 4, each of the two armatures 3B has a configuration of 3.9 poles and 5 teeth. The armatures 3B are arranged with a gap corresponding to 0.1 pole so that the electrical angles indicating the positions of the armatures 3B in the X direction are the same. The width Tw' of the tandem armature 11 in the X direction is the sum of the width Tw of the armature core 6B in each armature 3B and the width of the gap. The number of magnetic poles within the width Tw' is 7.9. In the linear motor 1D, the number of magnetic poles within the range of the width Tw of the armature core 6B in each armature 3B is a non-integer, and the number of magnetic poles within the range of the width Tw' of the tandem armature 11 is also a non-integer. is non-integer. Thus, the number of magnetic poles facing the tandem armature 11 is a non-integer number.

By arranging the two armatures 3B with a gap, magnetic interference between the armatures 3B can be reduced. The linear motor 1D can reduce cogging thrust by reducing magnetic interference between the armatures 3B. Since the electrical angles of the armatures 3B are the same, the phase induced voltage vectors of the armatures 3B match each other. Therefore, even if the armatures 3B are electrically connected to each other by parallel connection, the thrust ripple does not increase.

The arrayed armature of the linear motor 1D is not limited to the armature 3B described in the third embodiment. The arrayed armature may be composed of any of the armatures described in the first to third embodiments. Also, the arrayed armature is not limited to the tandem armature 11 composed of two armatures, and may be composed of three or more armatures. That is, the arrayed armature may be composed of a plurality of armatures arranged in the X direction and sharing the field pole 2, and the number of armatures constituting the arrayed armature is arbitrary. be. Again, the number of magnetic poles within the width of the arrayed armature in the X direction is a non-integer number. The number of coils 7 and the number of teeth 9 in each armature of the arrayed armature are arbitrary.

Also in the fourth embodiment, the linear motor 1D has the effect of reducing the cogging thrust while maintaining the thrust for driving the linear motor 1D, as in the first embodiment.

The configuration shown in each embodiment above is an example of the content of the present disclosure. The configuration of each embodiment can be combined with another known technique. Configurations of respective embodiments may be combined as appropriate. A part of the configuration of each embodiment can be omitted or changed without departing from the gist of the present disclosure.

1, 1A, 1B, 1C, 1D linear motor, 2 field magnetic poles, 3, 3A, 3B, 3C armature, 4 back yoke, 5 permanent magnet, 6, 6A, 6B armature core, 6a part, 7 coil, 8 core back, 9 teeth, 9a auxiliary teeth, 11 tandem armature.

Claims

a field pole each having a plurality of equally spaced permanent magnets;
An armature core having a plurality of teeth and a coil wound around each of two or more of the plurality of teeth, facing the field magnetic pole and facing the field magnetic pole an armature that moves in a static direction;
The armature in the advancing direction in combination of the number of the teeth of the armature core and the number of the magnetic poles facing the plurality of the teeth and arranged in the advancing direction of the armature A linear motor, wherein the number of magnetic poles within the width of the core is a non-integer number.
Each of the teeth around which the coil is wound has the same shape as each other,
the width of the armature in the direction of travel is shorter than the width of the field pole in the direction of travel;
Among the plurality of teeth, Nt is the number of teeth wound with the coil, L is the distance between the teeth at both ends in the traveling direction of the teeth wound with the coil, and L is the number of teeth with different polarities in the traveling direction. 2. The linear motor according to claim 1, wherein the value of {L×Nt/(Nt−1)}÷τp is a non-integer, where τp is the distance between the magnetic poles.
The number of turns of the coil in each of the plurality of phases is adjusted so that the amplitude of the projection component of the phase induced voltage vector onto the phase of the voltage for driving the linear motor is the same in each of the plurality of phases. 3. The linear motor according to claim 1 or 2, wherein:
The linear motor according to any one of claims 1 to 3, wherein the plurality of teeth includes the teeth wound with the coil and the teeth not wound with the coil.
The number of teeth included in the armature core is not an integer multiple of the number of phases, and the plurality of teeth includes the teeth wound with the coils of two or more phases out of the plurality of phases. 4. A linear motor according to any one of claims 1 to 3.
an arrayed armature composed of a plurality of the armatures arranged in the traveling direction and sharing the field magnetic poles;
6. The linear motor according to any one of claims 1 to 5, wherein the number of magnetic poles within the width of the arrayed armature in the traveling direction is a non-integer number.
The linear motor according to any one of claims 1 to 6, wherein all the coils attached to the plurality of teeth have the same wire diameter.