Variable reluctance type resolver

Abstract

A variable reluctance type resolver is provided. Among eight tooth pairs, one tooth pair is a non-use tooth pair to which an exciting coil is not wound, and the other seven tooth pairs are use tooth pairs to which the exciting coil is wound zero or multiple times. A number of windings Wa of the exciting coil wound around a tooth included in a use tooth pair in a 90° positional relationship with respect to the non-use tooth pair and a number of windings Wb of the exciting coil wound around a tooth included in a use tooth pair in a positional relationship other than the 90° positional relationship satisfy a relationship of 0 ≤ Wa ≤ 0.5 Wb. The number of windings Wa and the number of windings Wb can satisfy a relationship of 0 < Wa ≤ 0.5 Wb.

Description

TECHNICAL FIELD

[0001] The present application relates to a variable reluctance type rotary transformer. BACKGROUND

[0002] In the past, a rotation angle sensor that detects a rotation angle of a rotating body is known. The rotation angle sensor has a wide range of applications, such as a wheel speed sensor used in a powertrain of an automobile, a steering angle sensor of a steering wheel, and the like. For example, the rotation angle sensor is also used in a rotary drive unit of a robot, a conveyance device, and the like, an index table of an automatic assembly machine, a measuring machine, and the like, and a machining index of a numerical control machine tool, a special-purpose machine, and the like. The rotation angle sensor used in a harsh environment is required to have high environmental resistance. For example, an optical encoder and a magnetic encoder that have been used in the past for the rotation angle sensor are easily affected by temperature changes and electromagnetic fields, and have low environmental resistance. As a rotation angle sensor that achieves high environmental resistance, a rotary transformer is mentioned. A variable reluctance type rotary transformer (hereinafter referred to as "VR type rotary transformer") is known as one of the rotary transformers.

[0003] The VR type rotary transformer outputs a voltage according to a rotation angle using a change in magnetic resistance (magnetic reluctance) that occurs with rotation of a rotary transformer rotor. In a general VR type rotary transformer, an excitation coil and two output coils are wound around each tooth of a ring-shaped rotary transformer stator. Inside the rotary transformer stator, a rotary transformer rotor is arranged. The rotary transformer rotor has different distances (magnetic gaps) from each tooth in a circumferential direction. The excitation coil generates a magnetic field by flow of a current, and forms a magnetic circuit between the excitation coil and an adjacent rotary transformer rotor. The magnetic field strength changes with rotation of the rotary transformer rotor. The output coils output a voltage based on the magnetic field strength.

[0004] When the rotary transformer rotor rotates, the magnetic resistance in the magnetic circuit changes, and the voltages output by the two output coils change in a sinusoidal or cosine wave shape. During one rotation of the rotary transformer rotor, the two output coils output sinusoidal or cosine wave-shaped voltages. For example, the voltages output by the two output coils are signal-processed by an external signal processing circuit so as to calculate a rotation speed, a rotation angle, and the like of the rotary transformer rotor.

[0005] Various VR type rotary transformers are distinguished by being referred to as "nX", in which the number of periods of the sinusoidal or cosine wave-shaped voltages output during one rotation of the rotary transformer rotor is referred to as a multiplication factor n of an angle. For example, a VR type rotary transformer that outputs two periods of sinusoidal or cosine wave-shaped voltages during one rotation of the rotary transformer rotor is referred to as "2X". The multiplication factor n of an angle is determined by the shape of the rotary transformer rotor. Hereinafter, the number of slots (the number of teeth) of the rotary transformer stator is referred to as N.

[0006] Japanese Patent Application Laid-Open No. 2013-217852 (Patent Document 1) discloses an example of such a VR type resolver. Japanese Patent Application Laid-Open No. 2018-78755 (Patent Document 2) discloses various examples of VR type resolvers, each of which includes two teeth around which an excitation coil and two output coils are not wound.

[0007] When a resolver is arranged close to a motor, the magnetic field generated by the magnets of the motor rotor affects the resolver rotor, causing the following problems.

[0008] like Figure 6 As shown, magnets 120 are arranged in the motor rotor, alternating north and south poles along the circumferential direction. When the number of magnetic poles M of the motor rotor satisfies the relationship M = 2m (m: an even number), the magnetic poles in the motor rotor are arranged in point symmetry with respect to the core of the motor shaft. In short, north poles or south poles are arranged in point symmetry at any position along the circumferential direction of the motor rotor.

[0009] like Figure 7 As shown, the shape of resolver rotor 121 is point-symmetrical with respect to the motor shaft's core, and the arrangement of the winding directions of excitation coil 126 is also point-symmetrical with respect to the motor shaft's core. The circled letters R and L indicate the winding direction of the winding portion of excitation coil 126 wound around each tooth 124. For example, when looking outward from resolver rotor 121 toward tooth 124, the winding direction of the winding portion indicated by R is clockwise, and the winding direction of the winding portion indicated by L is counterclockwise. Therefore, the arrangement of the magnetic poles generated by excitation coil 126 is also point-symmetrical with respect to the motor shaft's core. In short, the north pole or south pole is generated with point symmetry at any position in the circumferential direction of the resolver rotor.

[0010] The magnetic field generated by the motor rotor is one in which magnetic poles alternate circumferentially, with identical magnetic poles arranged in point symmetry. When the distance between the motor rotor and the resolver rotor is small, magnetic poles identical to those generated by the motor rotor's magnets are generated in the resolver rotor. As a result, identical magnetic poles are arranged in point symmetry in the resolver rotor via the motor rotor's magnets.

[0011] When the motor rotor and resolver are closely arranged, the magnetic field generated by the motor rotor is superimposed on the magnetic field generated by the excitation coil. Both the magnetic field generated by the motor rotor and the magnetic field generated by the excitation coil have identical magnetic poles arranged in point-symmetry. Therefore, the magnetic field generated by the excitation coil is uniformly strengthened or weakened by the magnetic field generated by the motor rotor. As a result, the induced voltage generated in the output coil includes the induced voltage from the magnetic field generated by the motor rotor. Therefore, the magnetic field generated by the motor rotor can cause electrical errors. In particular, the induced voltage generated by the magnetic field of the motor rotor's magnets increases as the motor rotor's rotational speed increases. Consequently, electrical errors increase with increasing motor rotor rotational speed.

[0012] like Figure 8 As shown, in the VR type rotary transformer described in the first embodiment of Patent Document 2, the rotary transformer rotor 221 has four protrusions radially protruding from the shaft core, corresponding to an angle multiplication factor of 4. Among the eight tooth pairs consisting of sixteen teeth 224, one tooth pair is a non-used tooth pair 229 around which the excitation coil 226, the first output coil 227, and the second output coil 228 are not wound, and the other seven tooth pairs are used tooth pairs 230 around which the excitation coil 226 and the first output coil 227 or the second output coil 228 are wound. Figure 8 The VR type resolver shown can prevent electrical errors from occurring even when the magnetic field of the motor rotor having the same magnetic poles arranged in point symmetry is superimposed on the magnetic field generated by the excitation coil 226 .

[0013] A resolver detects the rotation angle of a rotating body by utilizing the property that magnetic resistance changes depending on the rotor position. Therefore, it is assumed that the total magnetic resistance of the excitation coil (i.e., the total impedance of the excitation coil) is constant in the resolver. However, when constructing a resolver with an angle multiplication factor n of 2 using the method described in Patent Document 2, the total impedance of the excitation coil changes depending on the rotor position. Therefore, although the current flowing through the excitation coil should be constant regardless of the rotor position, in reality the current changes depending on the rotor position. Consequently, the magnetic field of the excitation coil and the output voltage of the resolver also change depending on the rotor position, resulting in electrical errors. Summary of the Invention

[0014] The present invention has been made in view of the above circumstances. An object of the present invention is to provide a resolver that does not cause electrical errors even when the magnetic field of a motor rotor having identical magnetic poles arranged in point symmetry is superimposed on the magnetic field generated by an excitation coil, and that is capable of reducing the change in the total impedance of the excitation coil according to the rotor position, and whose angle multiplication factor is 2.

[0015] (1) A variable reluctance type resolver according to the present application is provided in a motor in which the number of magnetic poles M of a motor rotor satisfies the relationship M = 2m, m being an even number, and a multiplication factor of an angle thereof is 2. The variable reluctance type resolver includes a rotor installed coaxially with a motor shaft, a stator having sixteen teeth, and an exciting coil, a first output coil, and a second output coil selectively wound around the sixteen teeth. The sixteen teeth include eight tooth pairs. Each of the tooth pairs includes two teeth in a point-symmetrical positional relationship with respect to a shaft core of the rotor. Among the eight tooth pairs, one tooth pair is a non-use tooth pair around which the exciting coil is not wound, and the other seven tooth pairs are use tooth pairs around which the exciting coil is wound zero or more times. The exciting coil is wound around two teeth included in the use tooth pairs in opposite directions to each other to generate different magnetic poles. Among the teeth included in the use tooth pairs, the exciting coil is wound around two teeth adjacent to each other in a circumferential direction of the shaft core in opposite directions to each other. A number of windings Wa of the exciting coil wound around teeth included in a use tooth pair in a 90° positional relationship with respect to the non-use tooth pair and a number of windings Wb of the exciting coil wound around teeth included in a use tooth pair in a positional relationship other than the 90° positional relationship with respect to the non-use tooth pair satisfy the relationship 0 < Wa < 0.5 Wb.

[0016] According to the above-described configuration, since the exciting coil is wound around two teeth included in the use tooth pairs in opposite directions to each other to generate different magnetic poles, the exciting coil generates different magnetic poles in a point-symmetrical relationship. Here, the magnetic field generated by the magnets of the motor rotor in which the same magnetic poles are arranged in a point-symmetrical relationship is superimposed on the magnetic field generated by the exciting coil, thereby forming a resultant magnetic field. An induced voltage is generated in the first output coil and the second output coil by the resultant magnetic field. Among two winding portions in a point-symmetrical positional relationship in the exciting coil, the resultant magnetic field is strengthened in one winding portion, and the resultant magnetic field is weakened in the other winding portion. The induced voltage is strengthened by the resultant magnetic field in one winding portion, and the induced voltage is weakened by the resultant magnetic field in the other winding portion. As a result, the induced voltage as noise generated by the magnetic field of the motor rotor is canceled out. Therefore, even if the magnetic field of the motor rotor in which the same magnetic poles are arranged in a point-symmetrical relationship is superimposed on the magnetic field generated by the exciting coil, an electrical error does not occur.

[0017] Further, according to the above-described configuration, since the non-use tooth pair around which the exciting coil is not wound is provided, the exciting coil can alternately generate magnetic poles in the circumferential direction while the use tooth pairs around which the exciting coil is wound in opposite directions to each other are provided. In short, a resolver having a sixteen-tooth number of slots is realized.

[0018] Further, according to the above-described configuration, since the number of windings Wa and the number of windings Wb satisfy the relationship of 0 < Wa < 0.5 Wb, the total impedance of the excitation coil can be reduced according to a change in the position of the rotor. Therefore, the current flowing through the excitation coil, the magnetic field of the excitation coil, and the output voltage of the rotary transformer can be reduced according to a change in the position of the rotor, and thus it is possible to prevent an electrical error from occurring.

[0019] (2) Preferably, of the seven pairs of use teeth, five pairs of use teeth are first pairs of use teeth around which first output coils are wound, and the other two pairs of use teeth are second pairs of use teeth around which second output coils are wound. The first output coils are wound around two teeth included in the first pairs of use teeth in opposite directions to each other. The second output coils are wound around two teeth included in the second pairs of use teeth in opposite directions to each other.

[0020] According to the above-described configuration, while a pair of non-use teeth around which the excitation coil is not wound is provided, the first output coils and the second output coils are effectively arranged.

[0021] (3) Preferably, the rotor is arranged inside the stator.

[0022] (4) Preferably, the number of windings Wa and the number of windings Wb satisfy the relationship of 0 < Wa < 0.5 Wb.

[0023] According to the present application, even if the magnetic field of the rotor of the motor in which the same magnetic poles are arranged in point symmetry is superimposed on the magnetic field generated by the excitation coil, an electrical error does not occur. Further, it is possible to prevent the total impedance of the excitation coil from changing according to the position of the rotor, and it is possible to prevent an electrical error from occurring. Further, it is possible to prevent the total impedance of the excitation coil from changing according to the position of the rotor. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic view showing the configuration of a motor 10 provided with a rotary transformer 100 according to an embodiment of the present application.

[0025] Figure 2 is a schematic view of a motor rotor 17 of the motor 10 provided with the rotary transformer 100 according to the present embodiment.

[0026] Figure 3 is a schematic view showing the configuration of the rotary transformer 100 according to the present embodiment.

[0027] Figure 4 is a schematic view showing magnetic poles formed by the excitation coil 26, the first output coil 27, and the second output coil 28 in the rotary transformer 100 according to the present embodiment.

[0028] Figure 5 is a graph for explaining the effects of the rotary transformer 100 according to the present embodiment.

[0029] Figure 6 is a schematic view of a motor rotor of a motor provided with a conventional rotary transformer.

[0030] Figure 7 is a schematic view showing magnetic poles formed by an excitation coil 126, a first output coil 127, and a second output coil 128 in a conventional rotary transformer.

[0031] Figure 8 is a schematic view showing magnetic poles formed by an excitation coil 226, a first output coil 227, and a second output coil 228 in a rotary transformer described in Patent Literature 2. DETAILED DESCRIPTION

[0032] Hereinafter, a preferred embodiment of the present application will be described. Of course, the embodiment described below is merely an example of the present application, and the embodiment of the present application can be appropriately changed without changing the gist of the present application.

[0033] [MOTOR 10]

[0034] As shown in Figure 1 , a rotary transformer 100 according to an embodiment of the present application is provided in a motor 10. The motor 10 is a brushless motor. For example, the motor 10 is installed in an electric power steering (EPS). The motor 10 includes a motor body 11 and a control unit 12. The motor body 11 and the control unit 12 are electrically connected through a power cable 14 and a sensor cable 15.

[0035] The motor body 11 includes a motor stator 16, a motor rotor 17, a motor shaft 18 fixed to the motor rotor 17, and a housing 19. The motor shaft 18 is provided with the rotary transformer 100. The motor rotor 17 is arranged inside the motor stator 16. The motor 10 is an inner rotor type motor. The motor body 11 and the rotary transformer 100 are arranged in the housing 19.

[0036] Figure 2 The motor rotor 17 of the motor 10 is shown. The motor rotor 17 includes eight-pole magnets 20 fixed to the motor shaft 18. The magnets 20 are permanent magnets in which magnet particles are sintered into a cylindrical shape. In the magnets 20, N poles and S poles are alternately formed in a circumferential direction. In the magnets 20, the same magnetic poles are arranged in point symmetry.

[0037] In the motor 10, the number M of magnetic poles of the motor rotor 17 satisfies a relationship of M = 2m, where m is an even number. Since the motor rotor 17 includes eight-pole magnets 20, the number M of magnetic poles of the motor rotor 17 is 8. Since the number M of magnetic poles is 8, m is 4.

[0038] [ROTARY TRANSFORMER 100]

[0039] AsFigure 3 As shown, resolver 100 includes a resolver rotor 21 and a resolver stator 22. Resolver 100 is a so-called variable reluctance resolver. Resolver rotor 21 is arranged inside resolver stator 22. In short, resolver 100 is an inner rotor resolver. Resolver rotor 21 is coaxially mounted with motor shaft 18.

[0040] The resolver rotor 21 is constructed by stacking multiple non-oriented electrical steel sheets and securing them together using rivets or other methods. The outer periphery of the resolver rotor 21 is formed so that the gap permeance between the resolver rotor 21 and the resolver stator 22 changes sinusoidally with respect to the angle θ in the direction of rotation of the resolver rotor 21. The resolver 100 is a 2X resolver. The angle multiplication factor n of the resolver 100 is 2. Therefore, the outer periphery of the resolver rotor 21 is formed so that the same shape is periodically repeated every 180° (360° / 2), where 180° is an angle corresponding to the angle multiplication factor. The resolver rotor 21 has two protrusions radially protruding from the shaft core 13, corresponding to the angle multiplication factor of 2.

[0041] like Figure 3 As shown, the resolver stator 22 includes a yoke 23, sixteen teeth 24, and a coil assembly 25. The yoke 23 has a generally cylindrical shape. The sixteen teeth 24 protrude from the inner circumferential surface of the yoke 23 toward the shaft core 13 and are arranged at equal intervals along the circumference of the yoke 23. The yoke 23 and sixteen teeth 24 are constructed by laminating a plurality of non-oriented electrical steel sheets and securing the sheets together by rivets or the like.

[0042] The sixteen teeth 24 include first to sixteenth teeth 24(1) to 24(16) arranged in the circumferential direction of the yoke 23. The i-th tooth 24(i) is the tooth 24 corresponding to the order i from the first tooth 24(1). The order i is a number from 1 to 16. When there is no need to distinguish between teeth 24 having different orders, the teeth 24 are used as a general term.

[0043] The sixteen teeth 24 include eight tooth pairs. Each tooth pair includes two teeth 24 positioned in a point-symmetrical relationship with respect to the shaft core 13 of the resolver rotor 21. Hereinafter, when j is an integer ≥1 and ≤8, the tooth pair including the jth tooth 24(j) and the (j+8)th tooth 24(j+8) will be referred to as the "jth tooth pair." For example, the tooth pair including the first tooth 24(1) and the ninth tooth 24(9) will be referred to as the "first tooth pair."

[0044] The coil assembly 25 is Figure 4The entireties of the excitation coil 26, the first output coil 27, and the second output coil 28 are shown. The coil set 25 selectively winds some of the sixteen teeth 24. When a predetermined voltage is applied to the excitation coil 26, a sinusoidal or cosine wave-like output voltage is obtained from each of the first output coil 27 and the second output coil 28. The first output coil 27 and the second output coil 28 are wound so that phases of the output voltages are different from each other. In other words, when a sinusoidal wave-like voltage is output from the first output coil 27, a cosine wave-like voltage is output from the second output coil 28, and vice versa. Based on the output voltages of the first output coil 27 and the second output coil 28, the rotation angle of the resolver rotor 21, that is, the rotation angle of the motor shaft 18 can be detected.

[0045] Figure 4 The sixteen teeth 24, the excitation coil 26, the first output coil 27, and the second output coil 28 are shown. The excitation coil 26, the first output coil 27, and the second output coil 28 each have a plurality of winding portions that wind the teeth 24. In the drawing, the winding portions are indicated by the letters R and L. Figure 4 In the drawing, the circled letter R and the circled letter L indicate winding directions of the winding portions of the excitation coil 26 that wind each tooth 24. When the teeth 24 are viewed outward from the resolver rotor 21, the winding direction indicated by the letter R is one direction, and the winding direction indicated by the letter L is the other direction. One direction is a direction opposite to the other direction. For example, one direction is a clockwise direction, and the other direction is a counterclockwise direction. In the winding portions having the same winding direction, the same magnetic pole is generated. In the winding portions having different winding directions, different magnetic poles are generated.

[0046] Since an alternating voltage is applied to the excitation coil 26, the polarity of the magnetic field generated from the winding portions of the excitation coil 26 periodically inverts. Therefore, the polarity of the magnetic field generated in the winding portions of the first output coil 27 and the second output coil 28 by mutual induction also periodically inverts. For example, at a certain time, an N-pole magnetic field is generated in the winding portions in one direction indicated by the letter R, and an S-pole magnetic field is generated in the winding portions in the other direction indicated by the letter L. At another time, an S-pole magnetic field is generated in the winding portions in one direction indicated by the letter R, and an N-pole magnetic field is generated in the winding portions in the other direction indicated by the letter L.

[0047] Among the eight tooth pairs included in the resolver stator 22, one tooth pair is a non-use tooth pair 29, and seven tooth pairs are use tooth pairs 30. The excitation coil 26, the first output coil 27, and the second output coil 28 are not all wound around the teeth 24 included in the non-use tooth pair 29. The excitation coil 26 is wound zero or more times around the teeth 24 included in the use tooth pairs 30. Wound zero times means that the excitation coil 26 is not wound, and wound zero or more times means that the excitation coil 26 is wound one or more times or the excitation coil 26 is not wound. Among the seven use tooth pairs 30, five use tooth pairs 30 are first use tooth pairs 30A, and the other two use tooth pairs 30 are second use tooth pairs 30B. The first output coil 27 is wound around the teeth 24 included in the first use tooth pairs 30A. The second output coil 28 is wound around the teeth 24 included in the second use tooth pairs 30B. When it is not necessary to distinguish the first use tooth pairs 30A and the second use tooth pairs 30B, the use tooth pairs 30 are used as a general term.

[0048] As shown in FIG. 6, the fifth tooth pair is the non-use tooth pair 29, and the other seven tooth pairs are the use tooth pairs 30. Among the seven use tooth pairs 30, five use tooth pairs 30 are the first use tooth pairs 30A, and the other two use tooth pairs 30 are the second use tooth pairs 30B. Specifically, among the seven use tooth pairs 30, the first tooth pair, the second tooth pair, the fourth tooth pair, the sixth tooth pair, and the eighth tooth pair are the first use tooth pairs 30A, and the third tooth pair and the seventh tooth pair are the second use tooth pairs 30B. Figure 4 The excitation coil 26 is wound around each of the fourteen teeth 24 included in the seven use tooth pairs 30. The excitation coil 26 is wound in one direction indicated by the letter R around the first tooth 24(1), the third tooth 24(3), the sixth tooth 24(6), the eighth tooth 24(8), the tenth tooth 24(10), the twelfth tooth 24(12), and the fifteenth tooth 24(15). For example, when looking at the teeth 24 outward from the resolver rotor 21, one direction is a clockwise direction. The excitation coil 26 is wound in the other direction indicated by the letter L around the second tooth 24(2), the fourth tooth 24(4), the seventh tooth 24(7), the ninth tooth 24(9), the eleventh tooth 24(11), the fourteenth tooth 24(14), and the sixteenth tooth 24(16). For example, when looking at the teeth 24 outward from the resolver rotor 21, the other direction is a counterclockwise direction.

[0049]

[0050] ​The excitation coil 26 is wound around two teeth 24 included in the tooth pair 30 in opposite directions to each other. For example, in the first tooth pair, the excitation coil 26 is wound around the first tooth 24 (1) in one direction indicated by the letter R, and around the ninth tooth 24 (9) in the other direction indicated by the letter L. In the second tooth pair, the excitation coil 26 is wound around the second tooth 24 (2) in the other direction indicated by the letter L, and around the tenth tooth 24 (10) in one direction indicated by the letter R.

[0051] Among the fourteen teeth 24 included in the seven used tooth pairs 30, the excitation coil 26 is wound around two teeth 24 adjacent to each other in the circumferential direction of the rotary transformer rotor 21 in directions opposite to each other. For example, the excitation coil 26 is wound around the third tooth 24 (3) in one direction indicated by the letter R, and around the fourth tooth 24 (4) in the other direction indicated by the letter L. The winding direction in the third tooth 24 (3) is opposite to the winding direction in the fourth tooth 24 (4). The excitation coil 26 is wound around the sixth tooth 24 (6) in one direction indicated by the letter R. With respect to the fourth tooth 24 (4) and the sixth tooth 24 (6) between which the non-used tooth pair 29 is interposed, the winding direction in the fourth tooth 24 (4) is opposite to the winding direction in the sixth tooth 24 (6).

[0052] The first output coil 27 is wound around two teeth 24 included in the first used tooth pair 30A in directions opposite to each other. In the first tooth pair, the first output coil 27 is wound around the first tooth 24 (1) in one direction indicated by the letter R, and around the ninth tooth 24 (9) in the other direction indicated by the letter L. In the second tooth pair, the first output coil 27 is wound around the second tooth 24 (2) in the other direction indicated by the letter L, and around the tenth tooth 24 (10) in the one direction indicated by the letter R. In the fourth tooth pair, the first output coil 27 is wound around the fourth tooth 24 (4) in one direction indicated by the letter R, and around the twelfth tooth 24 (12) in the other direction indicated by the letter L. In the sixth tooth pair, the first output coil 27 is wound around the sixth tooth 24 (6) in the other direction indicated by the letter L, and around the fourteenth tooth 24 (14) in the one direction indicated by the letter R. In the eighth tooth pair, the first output coil 27 is wound around the eighth tooth 24 (8) in one direction indicated by the letter R, and around the sixteenth tooth 24 (16) in the other direction indicated by the letter L.

[0053] The second output coil 28 is wound in opposite directions to each other around two teeth 24 included in the second use tooth pair 30B. In the third tooth pair, the second output coil 28 is wound in one direction indicated by the letter R around the third tooth 24(3), and in the other direction indicated by the letter L around the eleventh tooth 24(11). In the seventh tooth pair, the second output coil 28 is wound in one direction indicated by the letter R around the seventh tooth 24(7), and in the other direction indicated by the letter L around the fifteenth tooth 24(15).

[0054] Among the seven use tooth pairs 30, the first tooth pair is in a 90° positional relationship with respect to the fifth tooth pair which is a non-use tooth pair 29. The number of windings of the excitation coil 26 which winds the teeth 24 included in the use tooth pair 30 which is in a 90° positional relationship with respect to the non-use tooth pair 29 is referred to as Wa.

[0055] Among the seven use tooth pairs 30, the second tooth pair, the third tooth pair, the fourth tooth pair, the sixth tooth pair, the seventh tooth pair, and the eighth tooth pair are in positional relationships other than a 90° positional relationship with respect to the fifth tooth pair which is a non-use tooth pair 29. The number of windings of the excitation coil 26 which winds the teeth 24 included in the use tooth pair 30 which is in a positional relationship other than a 90° positional relationship with respect to the non-use tooth pair 29 is referred to as Wb.

[0056] The resolver rotor 21 is configured so that the number of windings Wa of the excitation coil 26 which winds the teeth 24 included in the use tooth pair 30 which is in a 90° positional relationship with respect to the non-use tooth pair 29 and the number of windings Wb of the excitation coil 26 which winds the teeth 24 included in the use tooth pair 30 which is in a positional relationship other than a 90° positional relationship with respect to the non-use tooth pair 29 satisfy the relationship of 0 ≤ Wa ≤ 0.5 Wb.

[0057] The first tooth pair includes two teeth 24. The number of windings Wa of the excitation coil 26 which winds these two teeth 24 is the same. The second tooth pair, the third tooth pair, the fourth tooth pair, the sixth tooth pair, the seventh tooth pair, and the eighth tooth pair include a total of twelve teeth 24. The number of windings Wb of the excitation coil 26 which winds these twelve teeth 24 can all be the same, or some of the number of windings Wb can be different.

[0058] Reference Figure 5 The effects of the resolver 100 are described. Figure 5 The states in which the total impedance of the excitation coil 26 changes according to the rotor position are shown in the cases of Wa = Wb, Wa = 0.47 Wb, and Wa = 0. In the case of Wa = Wb, the amount of change in the total impedance of the excitation coil 26 according to the rotor position is large. In contrast, in the cases of Wa = 0.47 Wb and Wa = 0, the amount of change in the total impedance of the excitation coil 26 according to the rotor position is small, and it can be said that the total impedance of the excitation coil 26 hardly changes according to the rotor position.

[0059] [Effects of the operation of the embodiment]

[0060] According to the resolver 100 of the above-described embodiment, since the exciting coil 26 is wound in opposite directions to the two teeth 24 included in the use tooth pair 30 to generate different magnetic poles, the exciting coil 26 generates different magnetic poles in point symmetry. Here, the magnetic field generated by the magnets 20 of the motor rotor 17 in which the same magnetic poles are arranged in point symmetry is superimposed on the magnetic field generated by the exciting coil 26, and thus a resultant magnetic field is formed. An induced voltage is generated in the first output coil 27 and the second output coil 28 by the resultant magnetic field. In the two winding portions in the exciting coil 26 in a point symmetric positional relationship, the resultant magnetic field is strengthened in one winding portion, and the resultant magnetic field is weakened in the other winding portion. The induced voltage is strengthened by the resultant magnetic field in one winding portion, and the induced voltage is weakened by the resultant magnetic field in the other winding portion. As a result, the induced voltage as noise generated by the magnetic field of the motor rotor 17 is canceled out. Therefore, even if the magnetic field of the motor rotor 17 in which the same magnetic poles are arranged in point symmetry is superimposed on the magnetic field generated by the exciting coil 26, an electrical error does not occur.

[0061] Further, since the non-use tooth pair 29 in which the exciting coil 26 is not wound is provided while the use tooth pair 30 in which the exciting coil 26 is wound in opposite directions to each other is provided, the exciting coil 26 can alternately generate magnetic poles in the circumferential direction. In short, a resolver having a sixteen-tooth number slot is realized.

[0062] Further, since the number of windings Wa and the number of windings Wb satisfy the relationship of 0 ≤ Wa ≤ 0.5 Wb, the total impedance of the exciting coil 26 can be reduced in accordance with a change in the rotor position. Therefore, even if the multiplication factor of the angle is 2, the current flowing through the exciting coil, the magnetic field of the exciting coil, and the output voltage of the resolver can be reduced in accordance with a change in the rotor position, and thus an electrical error can be prevented from occurring.

[0063] Further, the first output coil 27 and the second output coil 28 are effectively arranged while the non-use tooth pair 29 in which the exciting coil 26 is not wound is provided.

[0064] [Modified examples]

[0065] Although the embodiment of the present application has been described in detail above, the above description is merely an example of the present application in all aspects. Of course, various improvements or modifications can be made without departing from the scope of the present application. As for the constituent parts of the resolver 100 according to the above-described embodiment, the constituent parts can be omitted, replaced, or added as appropriate according to the embodiment. Further, the shape and size of the constituent parts of the resolver 100 described above can be set as appropriate according to the embodiment.

[0066] The resolver according to the above-described embodiment is a resolver of an inner rotor type in which the resolver rotor is arranged inside the resolver stator. The resolver can be a resolver in which the resolver rotor is arranged outside the resolver stator. In this case, the motor provided with the resolver is also a motor of an outer rotor type.

[0067] The resolver according to the above-described embodiment is configured so that the number of windings Wa and the number of windings Wb satisfy the relationship of 0 ≤ Wa ≤ 0.5 Wb. The resolver according to the modified example can also be configured so that the number of windings Wa and the number of windings Wb satisfy the relationship of 0 < Wa ≤ 0.5 Wb.

[0068] Description of reference numerals

[0069] 17 motor rotor

[0070] 20 magnet

[0071] 21 resolver rotor

[0072] 22 resolver stator

[0073] 24 tooth

[0074] 26 excitation coil

[0075] 27 first output coil

[0076] 28 second output coil

[0077] 29 non-use tooth pair

[0078] 30 use tooth pair

[0079] 30A first use tooth pair

[0080] 30B second use tooth pair

[0081] 100 resolver

Claims

1. A variable reluctance resolver, wherein the variable reluctance resolver is provided in a motor and has an angle multiplication factor of 2. In the motor, the number of magnetic poles M of the motor rotor satisfies the relationship M=2m, where m is an even number, and wherein: The variable reluctance type rotary transformer includes: a rotor coaxially installed with a motor shaft; a stator having sixteen teeth; and an exciting coil, a first output coil, and a second output coil selectively wound around the sixteen teeth, wherein the sixteen teeth include eight tooth pairs, each of the tooth pairs includes two teeth in a point-symmetrical positional relationship with respect to a shaft core of the rotor, among the eight tooth pairs, one tooth pair is a non-use tooth pair around which the exciting coil is not wound, and the other seven tooth pairs are use tooth pairs around which the exciting coil is wound zero or more times, the exciting coil is wound around the two teeth included in the use tooth pairs in opposite directions to each other to generate different magnetic poles, among the teeth included in the use tooth pairs, the exciting coil is wound around two teeth adjacent to each other in a circumferential direction of the shaft core in opposite directions to each other, and a number of windings Wa of the exciting coil wound around the teeth included in the use tooth pairs in a 90° positional relationship with respect to the non-use tooth pair and a number of windings Wb of the exciting coil wound around the teeth included in the use tooth pairs in a positional relationship other than the 90° positional relationship satisfy a relationship of 0 < Wa ≤ 0.5Wb.

2. The variable-reluctance type resolver according to claim 1, characterized by, wherein among the seven use tooth pairs, five use tooth pairs are first use tooth pairs around which the first output coil is wound, and the other two use tooth pairs are second use tooth pairs around which the second output coil is wound, the first output coil is wound around the two teeth included in the first use tooth pairs in opposite directions to each other, and the second output coil is wound around the two teeth included in the second use tooth pairs in opposite directions to each other.

3. The variable-reluctance type resolver according to claim 1, characterized by, wherein the rotor is disposed inside the stator.

4. The variable reluctance rotary transformer according to claim 2, wherein: wherein the rotor is disposed inside the stator.

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