Wound-field type electric motor and rotor

Abstract

To provide a wound-field electric motor and rotor that are compact and capable of achieving high efficiency. [Solution] The electric motor (10) is a wound-field electric motor comprising a rotor (11) and a stator (12). The rotor is rotatably mounted around a rotation axis (C) and has a plurality of rotor cores (111n) on which a plurality of first windings (W1n) are arranged. The stator is mounted in the circumferential direction (A) of the rotor and has a plurality of stator cores (121n) on which a plurality of second windings (W2n) are arranged. The second windings are installed circumferentially with respect to the stator core and are configured to generate a second magnetic flux in the radial direction (B) of the rotor. The first windings are installed radially with respect to the rotor core and are configured to generate a first magnetic flux in the circumferential direction. The electric motor is configured to form a rotating magnetic field by utilizing the magnetic poles on both sides of the first magnetic flux generated in the rotor.

Description

[Technical Field]

[0001] The technology disclosed herein relates to a wound-field electric motor. [Background technology]

[0002] Motor technology is attracting attention as one of the technological themes related to green innovation. Examples of motors include permanent magnet synchronous motors (PMSMs) and electrically excited synchronous motors (EESMs). Wound-field synchronous motors are motors in which the magnitude of the rotor's field magnetic flux (hereinafter simply referred to as "magnetic flux") can be adjusted by replacing the permanent magnets installed on the rotor with windings and controlling the supplied current (see Patent Document 1). Because wound-field synchronous motors do not use permanent magnets, they do not require the use of rare earth elements such as neodymium magnets. Therefore, these motors have the advantage of enabling stable manufacturing and supply to the market. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-204014 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In electric motors, considering the diverse range of applications, miniaturization and increased efficiency are desirable. In particular, in conventional wound-field synchronous motors, the magnetic poles formed in the radial direction of the rotor depend on the method of winding the windings on the rotor's iron core (teeth) (how the wires are wound around the teeth), resulting in either a south pole on the outside of the rotor and a north pole on the inside, or a south pole on the inside and a north pole on the outside. Therefore, in conventional configurations, one side of the magnetic flux generated in the rotor is short-circuited (either the north or south pole is not utilized as a rotating magnetic field). Consequently, there is room for improvement in terms of increasing efficiency in conventional configurations.

[0005] The technology disclosed herein aims to provide a wound-field electric motor and rotor that are compact and capable of achieving high efficiency. [Means for solving the problem]

[0006] The technology of this disclosure employs the following technical means to solve the above-mentioned problems. The claims and the reference numerals in parentheses in this section are examples that indicate the correspondence with the specific means described in the embodiments described later as one aspect. Therefore, they do not limit the technical scope of this disclosure.

[0007] An electric motor (10) in one aspect of the technology of this disclosure is a wound-field electric motor comprising a rotor (11) and a stator (12). The rotor is rotatably mounted about a rotation axis (C) and has a plurality of rotor cores (111n) on which a plurality of first windings (W1n) are arranged. The stator is mounted in the circumferential direction (A) of the rotor and has a plurality of stator cores (121n) on which a plurality of second windings (W2n) are arranged. The second windings are installed circumferentially with respect to the stator cores and are configured to generate a second magnetic flux in the radial direction (B) of the rotor. The first windings are installed radially with respect to the rotor cores and are configured to generate a first magnetic flux in the circumferential direction. The electric motor is configured to form a rotating magnetic field using the magnetic poles on both sides of the first magnetic flux generated in the rotor.

[0008] Another aspect of the technology of the present disclosure, the rotor (11) is a rotor applied to a wound-field motor (10). The motor includes a stator (12). The stator is provided in the circumferential direction (A) of the rotor and has a plurality of stator cores (121n) in which a plurality of second windings (W2n) are respectively arranged. The second windings are installed in the circumferential direction with respect to the stator core and are configured to generate a second magnetic flux in the radial direction (B) of the rotor. The rotor is provided rotatably about a rotation axis (C) and has a plurality of rotor cores (111n) in which a plurality of first windings (W1n) are respectively arranged. The first windings are installed in the radial direction with respect to the rotor core and are configured to generate a first magnetic flux in the circumferential direction. The rotor is provided such that the motor forms a rotating magnetic field by using the magnetic poles on both sides of the first magnetic flux generated in the rotor.

Effect of the Invention

[0009] According to the above aspect of the technology of the present disclosure, in the rotor, a magnetic flux is generated in the circumferential direction instead of the radial direction, and the motor is configured to form a rotating magnetic field by using the magnetic poles on both sides of the magnetic flux generated in the rotor. In other words, the technology of the present disclosure is configured to form a rotating magnetic field by using the magnetic poles on both sides without short-circuiting any one of the magnetic poles of the magnetic flux generated by the rotor. Thereby, a wound-field motor and a rotor that can be miniaturized and have high efficiency can be provided.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a schematic configuration diagram of a motor according to the first embodiment. [Figure 2] FIG. 2 is a schematic configuration diagram of a drive system of a motor according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view in a direction perpendicular to the rotation axis of a motor according to the first embodiment. (a) is an A-A cross-sectional view showing a schematic configuration of a rotor and a stator, and (b) is an enlarged view of the A-A cross-section showing a schematic configuration of the rotor. [Figure 4]FIG. 4 is a diagram showing a state where windings are installed on the rotor according to the first embodiment. (a) is a plan view showing a state where windings are installed on the rotor, and (b) is a perspective view showing a state where windings are installed on the rotor. [Figure 5] FIG. 5 is a comparison diagram between a conventional magnetic field circuit and the magnetic field circuit according to the first embodiment. (a) is a diagram showing the conventional magnetic field circuit, and (b) is a diagram showing the magnetic field circuit according to the first embodiment. [Figure 6] FIG. 6 is a comparison diagram between a conventional rotor and the rotor according to the first embodiment. (a) is a diagram showing a 1 / 8 model of the conventional rotor, and (b) is a diagram showing a 1 / 8 model of the rotor according to the first embodiment.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments according to the technology of the present disclosure will be described with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and repeated explanations will be omitted as appropriate.

[0012] <First Embodiment> FIG. 1 is a schematic configuration diagram of the motor 10 according to the present embodiment. The motor 10 according to the present embodiment has a rotor (rotor) 11 that forms a magnetic flux by an electromagnet (winding), and is a wound-field synchronous motor that can control the power factor by adjusting the current (field current) flowing through the winding.

[0013] As shown in FIG. 1, the motor 10 mainly includes a rotor 11, a stator 12, an output shaft 13, and a housing case 14. The rotor 11 does not have a permanent magnet. The rotor 11 has a plurality of armature windings 1Wn (hereinafter, referred to as "first winding W1n" for convenience). The rotor 11 is provided with a plurality of winding installation portions (a plurality of holes and grooves for installing windings) at predetermined intervals, and the first winding W1n is installed in each winding installation portion. That is, the first winding W1n is arranged on the rotor 11 at predetermined intervals.

[0014] The rotor 11 is fixed to the output shaft 13. The rotor 11 outputs rotational force generated by the rotational drive to the load to be driven via the output shaft 13.

[0015] The stator 12 is provided circumferentially around the rotor 11 to provide a force to rotate the rotor 11. The stator 12 has multiple armature windings W2n (hereinafter referred to as "second windings W2n" for convenience). Similar to the rotor 11, the stator 12 is constructed of multiple iron cores provided at predetermined intervals, with the second windings W2n installed on each iron core. In other words, the second windings W2n are arranged on the stator 12 at predetermined intervals. The stator 12 is fixed to the housing case 14 via a bracket (not shown). The output shaft 13 is supported by a bearing (not shown). The bearing is supported by the housing case 14.

[0016] Furthermore, the electric motor 10 has a slip ring 15 and a brush 16. The slip ring 15 and brush 16 are one of the electrical components for supplying current to the first winding W1n of the rotor 11.

[0017] Here, we will illustrate the drive system (drive circuit) according to this embodiment and explain the control configuration for driving the electric motor 10. Figure 2 is a schematic diagram of the drive system 100 for the electric motor 10 according to this embodiment.

[0018] The slip rings 15 are electrically connected to the first winding W1n. The slip rings 15 are fixed to the output shaft 13, similar to the rotor 11. The slip rings 15 are fixed to the output shaft 13 in a number corresponding to the number of connection terminals of the first winding W1n, and are in constant contact with and electrically connected to the connection terminals of the first winding W1n. Each adjacent slip ring 15 is electrically insulated.

[0019] The brush 16 is in constant contact with and electrically connected to the slip ring 15. The brush 16 is connected to an external power source 19 (e.g., a battery) via a predetermined conductive path. Thus, the motor 10 is configured such that current output from the external power source 19 flows through the brush 16 to the slip ring 15, and is supplied to the first winding W1n of the rotor 11 via the slip ring 15.

[0020] Since the slip ring 15 is fixed to the same output shaft 13 as the rotor 11, it rotates along with the rotation of the rotor 11. As a result, the direction of the current flowing through the first winding W1n changes.

[0021] The stator 12 is connected to an external power supply 19 via a predetermined conductive path. Therefore, the motor 10 is configured such that the current output from the external power supply 19 is supplied to the second winding W2n of the predetermined stator 12.

[0022] Furthermore, the drive system 100 has the following control circuit. A three-phase inverter (three-phase AC conversion circuit) 17 is provided between the stator 12 and the external power supply 19. The stator 12 is configured to be driven by PWM (Pulse Width Modulation) control (PWM control) via the three-phase inverter 17. The three-phase inverter 17 converts DC to three-phase AC of U-phase, V-phase, and W-phase. The three-phase inverter 17 uses a control method in which one of the three phases always carries current. With this method, fluctuations in output current are smaller compared to a single-phase inverter, the torque of the motor is stable, and vibrations and noise are suppressed. For this reason, three-phase inverters are generally used to drive motors.

[0023] The three-phase inverter 17 is electrically connected to a microcontroller (not shown) equipped with, for example, one or more arithmetic circuits (processors). The microcontroller reads a predetermined program from its memory and executes it using its processor, thereby outputting a predetermined control signal to the three-phase inverter 17. As a result, the three-phase inverter 17 performs PWM control.

[0024] A DC / DC converter (DC-DC conversion circuit) 18 is provided between the rotor 11 and the external power supply 19. The DC / DC converter 18 converts a DC voltage to another DC voltage, that is, it converts DC voltages. In this embodiment, the DC / DC converter 18 adjusts the voltage output from the external power supply 19 and input to the rotor 11 according to the operating voltage of the rotor 11, and functions to stabilize the operation of the rotor 11.

[0025] In this configuration, when a three-phase current is applied to the second winding W2n of the stator 12 (excited), a rotating magnetic field is generated that rotates at a rotational speed determined by the frequency of the three-phase current (i.e., synchronous speed). As a result, the rotor 11 is attracted and rotated by the generated rotating magnetic field. In Figure 1, the direction of the rotation axis C (central axis of the output shaft) of the rotor 11 is indicated by reference numeral Y, the direction perpendicular to the rotation axis C is indicated by reference numeral Z, and the direction horizontal to the rotation axis C is indicated by reference numeral X. These three-dimensional directions will be used in the same sense in the following explanation.

[0026] The technology disclosed herein proposes a configuration that achieves high efficiency while maintaining a compact size compared to conventional electric motors. In this disclosure, "high efficiency" means achieving higher output (higher torque) than a conventional electric motor (comparison model) even while maintaining the same size. Furthermore, it means that the electric motor can be made even smaller while maintaining the same output.

[0027] One method for achieving high efficiency is to increase the winding's fill factor (the ratio of the conductor to the coil space). As a characteristic of electric motors, the more windings there are, the higher the motor's output. On the other hand, simply increasing the number of windings makes the motor larger. Therefore, in order to achieve high efficiency while maintaining a compact size, it is necessary to increase the winding's fill factor.

[0028] The inventors of this invention conducted thorough research considering the above points. As a result, unlike the conventional configuration in which one side of the magnetic flux is short-circuited, the inventors devised a configuration in which both sides of the magnetic flux formed by the first winding W1n can be used as a rotating magnetic field.

[0029] As described above, in conventional configurations, one of the magnetic poles of the magnetic flux generated in the rotor is not used as a rotating magnetic field (it does not act on the rotational force). In contrast, the technology of this disclosure employs a configuration in which both magnetic poles of the magnetic flux generated in the rotor are used as a rotating magnetic field (it acts on the rotational force), generating approximately 1.8 times the magnetic flux of the conventional configuration. With this configuration, the technology of this disclosure provides an electric motor that achieves high efficiency while maintaining a compact size (an electric motor with high output at the same size).

[0030] (stator) Figure 3 shows a cross-sectional view of the electric motor 10 according to this embodiment, perpendicular to the rotation axis C (rotation axis C of the rotor 11) in the direction Z. Figure 3(a) is a cross-sectional view AA showing the schematic configuration of the rotor 11 and stator 12 according to this embodiment. Figure 3(b) is an enlarged view of the cross-sectional view AA showing the schematic configuration of the rotor 11 according to this embodiment. In Figure 3, the circumferential direction of the electric motor 10 (rotor 11) is indicated by reference numeral A, and the radial direction of the electric motor (rotor) is indicated by reference numeral B. The terms circumferential and radial directions will be used with the same meaning in the following description.

[0031] Figure 3(a) shows an example configuration in which the ratio of the number of poles between the stator 12 and the rotor 11 is 6n:4n. Specifically, it shows an example configuration of an electric motor 10 having 8 poles in the rotor 11 and 12 poles in the stator 12.

[0032] As shown in Figure 3(a), the stator 12 has multiple second windings W2n (W21-W2 12 Multiple coil spaces for installing ) WS2n (WS21-WS2 12) is provided. The stator 12 has one stator core 121n between the coil spaces WS2n of the stator 12 in the circumferential direction A. In this embodiment, there are a total of 12 stator cores 121n (1211 - 121 12 ) are provided. Therefore, each stator core 121n corresponds to the second pole forming portion. Each stator core 121n is arranged in the stator 12 at a predetermined interval (at a predetermined position) in the circumferential direction A. When the number of poles is 12, each stator core 121n (the pole of the stator 12) is arranged within a range of a central angle of 30° (= 360° / 12) with respect to the rotation axis C.

[0033] Also, the coil space WS2n is provided on both sides of each stator core 121n in the circumferential direction A. Specifically, as shown in Fig. 3(a), on both sides of the stator core 121 n+1 in the circumferential direction A, a pair of coil spaces WS2n (the first coil space WS21 and the second coil space WS22) are provided. The first coil space WS21 is a space commonly used by the adjacent first stator core 121 n and the second stator core 121 n+1 and is a space where two adjacent stator cores 121 n , 121 n+1 each use half of the volume. The second coil space WS22 is a space commonly used by the adjacent second stator core 121 n+1 and the third stator core 121 n+2 and is a space where two adjacent stator cores 121 n+1 , 121 n+2 each use half of the volume. Also, the first coil space WS21 and the second coil space WS22 are spaces with the same cross-sectional area and the same volume.

[0034] Each stator core 121n is provided with a second winding W2n in the circumferential direction A. Specifically, a conductor is wound around each stator core 121n in the circumferential direction A. As a result, each stator core 121n has two coil spaces WS2n on both sides of the circumferential direction A, each of which is provided with a second winding W2n. In other words, in the stator 12 according to this embodiment, a second magnetic flux (longitudinal magnetic flux: magnetic poles of S and N on both sides of the radial direction B) is generated along the radial direction B.

[0035] Furthermore, a gap is provided between the stator 12 and the rotor 11 in the radial direction B, allowing the rotor 11 to rotate with the stator 12 positioned around it. Each stator core 121n is formed extending from the inside (rotor 11 side) to the outside in the radial direction B with respect to the rotation axis C. The first end of each stator core 121n in the radial direction B is located on the outside of the motor 10, and the second end in the radial direction B is located on the pole-facing surface relative to the rotor 11.

[0036] As described above, each stator core 121n has a second winding W2n installed in the coil space WS2n in the circumferential direction A, and is excited when current (armature current) flows through the winding W2n. As a result, each stator core 121n forms a predetermined magnetic field. In addition, current of each phase of the three-phase current flows through the second winding W2n of each stator core 121n. Each second winding W2n is connected so that the current of the same phase flows through every three windings. If the phases of the three-phase current (three phases with a phase difference of 120° (1 / 3 period) each) are called phase I, phase II, and phase III, then each second winding W2n is assigned phases I, II, and III in the circumferential direction A in order. Figure 3(a) shows each stator core 121 with phase I current flowing through it. I(n) , each stator core 121 through which the II-phase current flows II(n) , each stator core 121 through which the III-phase current flows III(n) However, an example of stators 12 assigned sequentially in the circumferential direction A is shown.

[0037] In this configuration, in each stator core 121n, an N pole is generated in the stator core 121n with a high three-phase voltage, and an S pole is generated in the stator core 121n with a low three-phase voltage. The currents of each phase, I, II, and III, change sinusoidally with a 120° phase shift. Therefore, the magnetic poles (N pole or S pole) and magnetic field generated from each stator core 121n change over time. For example, if we focus only on the stator core 121n that generates an N pole, the stator core 121 in phase I I(n) → Phase II stator core 121 II(n) → Phase III stator core 121 III(n) →I-phase stator core 121 I(n) The source of the problem then changes.

[0038] In this embodiment, the electric motor 10 energizes the rotor 11 in accordance with the change in the magnetic poles of the stator 12, thereby forming a rotating magnetic field. As a result, the rotor 11 rotates in a clockwise or counterclockwise direction, with the rotor core 111n being attracted to the stator core 121n corresponding to the energized phase.

[0039] (rotor) As shown in Figures 3(a) and 3(b), the rotor 11 is provided with multiple coil spaces WS1n (WS11-WS18) for installing multiple first windings W1n (W11-W18). In the radial direction B, the rotor 11 has one rotor core 111n between each coil space WS1n of the rotor 11, and in this embodiment, there are a total of 8 rotor cores 111n (1111-1118). Therefore, each rotor core 111n corresponds to a first pole forming section. Each rotor core 111n is arranged at a predetermined interval (at a predetermined position) in the circumferential direction A of the rotor 11. When there are 8 poles, each rotor core 111n (pole of the rotor 11) is arranged within a range of a central angle of 45° (=360° / 8) with respect to the rotation axis C.

[0040] Furthermore, coil spaces WS1n are provided on both sides of the rotor core 111n in the radial direction B. Specifically, as shown in Figure 3(b), a pair of coil spaces WS1n (the first coil space HL1 and the second coil space HL2), corresponding to the winding installation area, are provided on both sides of the rotor core 111n in the radial direction B (two locations: the inside and outside of the radial direction B relative to the rotation axis C (on the stator 12 side)). In other words, the rotor core 111n is located between the first coil space HL1 and the second coil space HL2.

[0041] The first coil space HL1 is located radially in the direction B, at a distance rd1 from the rotation axis C of the rotor 11, and is positioned on the stator 12 side. On the other hand, the second coil space HL2 is located radially in the direction B, at a distance rd2 from the rotation axis C of the rotor 11, and is positioned on the rotation axis C side. In other words, distance rd1 is longer (larger) than distance rd2. Therefore, the first coil space HL1 and the first coil space HL2 are separated radially in the direction B by a predetermined distance d (=rd1-rd2-h2). Note that the above distance d is also called the distance between coils.

[0042] Furthermore, the first coil space HL1 and the second coil space HL2 are spaces with the same cross-sectional area and volume. Specifically, the width w1 and height h1 of the first coil space HL1 in the cross-section in the radial direction B are the same as the width w2 and height h2 of the second coil space HL2. Therefore, the area of ​​the first coil space HL1 (=w1×h1) in the cross-section in the radial direction B is the same as the area of ​​the second coil space HL2 (=w2×h2). Moreover, the depth dp1 of the first coil space HL1 in the rotation axis direction Y is the same as the depth dp2 of the second coil space HL2. Therefore, the volume of the first coil space HL1 (=w1×h1×dp1) is the same as the volume of the second coil space HL2 (=w2×h2×dp2). In this way, since the first coil space HL1 and the second coil space HL2 have the same volume, in this embodiment, they can be configured to have approximately the same space factor.

[0043] Figure 4 shows the rotor 11 according to this embodiment with the first winding W1n installed. Figure 4(a) is a plan view, and Figure 4(b) is a perspective view. As shown in Figure 4(a), each rotor core 111n has each first winding W1n provided in the radial direction B. Specifically, a conductor is wound around each rotor core 111n in the radial direction B. As a result, each rotor core 111n has each first winding W1n provided in the coil spaces WS1n on both sides (2) of the radial direction B. In other words, in the rotor 11 according to this embodiment, a first magnetic flux (transverse magnetic flux: magnetic poles of S and N on both sides of the circumferential direction A) is generated along the circumferential direction A.

[0044] Figure 5 is a comparison diagram of a conventional magnetic field circuit and the magnetic field circuit according to this embodiment. In the conventional rotor 21, the magnetic field winding is provided in the circumferential direction A, similar to the stator 22. Therefore, in the conventional rotor 21, a second magnetic flux (longitudinal magnetic flux: magnetic poles of S and N on both sides of radial direction B) is generated along the radial direction B, and the magnetic field circuit shown in Figure 5(a) is formed. In the conventional configuration, one of the magnetic poles of the magnetic flux is short-circuited to one of the magnetic poles of the other magnetic flux, and one of the magnetic poles, either the N or S, is not used as a rotating magnetic field.

[0045] In contrast, the rotor 11 according to this embodiment generates a first magnetic flux along the circumferential direction A, forming the magnetic field circuit shown in Figure 5(b). In the configuration of this embodiment, neither of the magnetic poles of the magnetic flux is short-circuited, and both the N pole and the S pole can be used as a rotating magnetic field.

[0046] Furthermore, the method of installing the first winding W1n is not limited to simply winding the conductor. As shown in Figure 4(b), for example, the first winding W1n may be shaped into a U-shape, and the shaped U-shaped first winding W1n may be inserted into the first coil space HL1 and the second coil space HL2. Moreover, the cross-sectional shape of the first winding W1n (the cross-sectional shape of the conductor) is not limited to a circular shape (the conductor is not limited to a round wire). In order to increase the space utilization ratio, the cross-sectional shape of the first winding W1n (the cross-sectional shape of the conductor) may be angular, and a flat rectangular wire may be used as the conductor.

[0047] As described above, each rotor core 111n has a first winding W1n installed radially in the coil space WS1n in the radial direction B, and is excited when an electric current (field current) flows through the winding W1n. As a result, each rotor core 111n forms a predetermined magnetic field. In addition, a first magnetic flux (transverse magnetic flux) is generated along the circumferential direction A in each rotor core 111n. Therefore, the electric motor 10 according to this embodiment is configured to be able to use both the N pole and the S pole as a rotating magnetic field. Furthermore, in the configuration of this embodiment, two rotor cores 111 n ,111 n+1 A single stator core 121n (a single electromagnet) is positioned approximately in the center between the two opposing electromagnets. As a result, as shown in Figure 5(b), the magnetic flux, which was dispersed on both sides in the conventional configuration, is concentrated on one side in the configuration of this embodiment. Consequently, a strong rotating magnetic field is obtained in the motor 10 according to this embodiment.

[0048] (Comparison results) Figure 6 is a comparison diagram of a conventional rotor 21 and the rotor 11 according to this embodiment. Figure 6(a) shows a 1 / 8 model of the conventional rotor 21, and Figure 6(b) shows a 1 / 8 model of the rotor 11 according to this embodiment.

[0049] (comparison standard) First, let's explain the comparison criteria. In order to compare the conventional configuration with the configuration of this embodiment, it is necessary to use rotors of the same dimensions (size). Therefore, we will use a model like the one shown in Figure 6. Specifically, both rotors being compared have 8 poles, and we will use a 1 / 8 model, which is a section of a rotor with the rotor core located in the center. Furthermore, the outer diameter of both rotors being compared is 128.6 [mm], the field source of the rotor is a field winding, and the cooling method is oil cooling.

[0050] (Conventional configuration) As shown in Figure 6(a), the rotor core 211n of the rotor 21 of the conventional electric motor 20 is provided with two coil spaces WS3n on both sides in the circumferential direction A. Field windings are installed in the coil spaces WS3n.

[0051] In a conventional rotor 21, the first length a of the coil space WS3n is 24 mm, and the second length b is 11 mm. The width c of the rotor core 211n is 19 mm. Note that the width c is also called the distance between coils. In this conventional configuration, the cross-sectional area occupied by the magnetic field winding relative to the coil space WS3n is 132 mm². 2 ](=(24[mm]×11[mm]) / 2).

[0052] (Configuration of this embodiment) As shown in Figure 6(b), the rotor core 111n of the rotor 11 of the electric motor 10 according to this embodiment is provided with two coil spaces WS1n (a first coil space HL1 and a second coil space HL2) on both sides in the radial direction B. The first winding W1n is installed in the coil space WS1n.

[0053] In the rotor 11 according to this embodiment, the first length a (corresponding to the height h1) of the first coil space HL1 is 10 [mm], and the second length b (corresponding to the width w1) is 8 [mm]. The dimensions of the second coil space HL2 are the same as those of the coil space HL1. The width c (corresponding to the distance d between coils) of the rotor core 111n is 27.8 [mm].

[0054] In this configuration, the cross-sectional area occupied by the first winding W1n relative to the coil space WS1n is 80 [mm²] 2 ](=10[mm]×8[mm]). As described above, in this embodiment, the configuration allows both sides of the first magnetic flux (transverse magnetic flux) formed by the first winding W1n to be used as a rotating magnetic field. Therefore, the occupied cross-sectional area of ​​the first winding W1n is twice that, 160[mm] 2 ](=80[mm 2 This corresponds to ] × 2).

[0055] (Example of comparative calculation) To demonstrate the technical effectiveness (high output (high torque)) of the configuration of this embodiment compared to the conventional configuration, the generated magnetic flux φ[Tm] is calculated using a predetermined formula based on the distance between the coils and the occupied cross-sectional area. 2 I calculated [ ].

[0056] Magnetic flux φ is given by the area S[m²] multiplied by the magnetic flux density B[T]. 2 This value is calculated by multiplying by ] (φ=BS). The magnetic flux density B between the coils can be determined by the magnetomotive force F[A]. Furthermore, in the conventional configuration, one side of the generated magnetic flux φ is short-circuited and unused, whereas in the configuration of this embodiment, both sides of the generated magnetic flux φ are utilized. Therefore, the comparative calculation using the generated magnetic flux φ is (27.8[mm] / 19[mm])×((80[mm 2 ]×2) / 132[mm 2 ]) . As a result, the calculated value is 1.77. In this embodiment, it is possible to generate a magnetic flux φ approximately 1.8 times greater than in the conventional configuration.

[0057] In the configuration of this embodiment, the coil space WS1n, i.e., the cross-sectional area occupied by the first winding W1n, is 80 [mm²]. 2 ]) conventional configuration (132[mm 2 It is smaller than ]). Therefore, in the configuration of this embodiment, the magnetomotive force F is smaller than in the conventional configuration. However, in the saturation region, the excitation curves become parallel (slope is zero), and there is no significant difference in the magnetic flux density Bm (saturation magnetic flux density) in the saturation region between the conventional configuration and the configuration of this embodiment. Even if there is a difference, it is only about 0.1 [T]. Therefore, the magnetomotive force F can be treated as not having a significant effect on the comparative calculation results. Even considering the magnetomotive force F, the comparative calculation results are approximately 1.5 times higher.

[0058] In this embodiment, the magnetic flux density B on the surface of the rotor 11 can be calculated by dividing the generated magnetic flux φ on both sides by the area S of the corresponding region on the surface of the rotor 11. Therefore, for example, even if the magnetomotive force F is 1.0 [T], the magnetic flux density B on the surface of the rotor 11 will be 1.5 [T]. Thus, in the configuration of this embodiment, the magnetomotive force F required to obtain the magnetic flux density B on the surface of the rotor 11 can be small (the required magnetomotive force F can be suppressed). The magnetomotive force F is calculated by multiplying the number of turns N of the conductor by the current I. Therefore, a configuration that can suppress the magnetomotive force F required to obtain the magnetic flux density B means that the current supplied to the rotor 11 (magnetic field current) can be reduced, which contributes to achieving high efficiency.

[0059] (Optimization of coil space dimensions) Through diligent research by the inventors, the output (torque) of the electric motor 10 according to this embodiment is greater than that of the conventional electric motor 20 (the magnetic flux is greater), and the occupied cross-sectional area of ​​the first winding W1n is set to 80 [mm²]. 2 ]) is being determined.

[0060] The eight rotor cores 111n (1111-1118), corresponding to the number of poles, are arranged at equal intervals in the circumferential direction B relative to the total surface area of ​​the rotor 11. Therefore, in the rotor 11, the surface area of ​​the circumferential region on the side of the rotation axis C is smaller (narrower) than the surface area of ​​the circumferential region on the side of the stator 12, which is spaced radially B away from the rotation axis C. Thus, the maximum value of the occupied cross-sectional area of ​​the first winding W1n depends on the size of either the first coil space HL1 or the second coil space HL2, which are located in the circumferential region on the side of the rotation axis C, among the two coil spaces WS1n.

[0061] For example, if the cross-sectional area occupied by the first winding W1n relative to the coil space WS1n is horizontally elongated (height h1 × width w1 = 4 [mm] × 20 [mm]), the spacing between the first and second coil spaces HL1 / HL2 in the circumferential region on the rotation axis C side becomes smaller, which may lead to manufacturing problems (difficulty in manufacturing) and product structural problems (reduced strength). On the other hand, if the cross-sectional area occupied by the first winding W1n relative to the coil space WS1n is vertically elongated (height h1 × width w1 = 20 [mm] × 4 [mm]), the width c (d distance between coils) of the rotor core 111n in the radial direction B becomes shorter than 27.8 [mm] (24.3 [mm] = ((128.6 [mm] / 2) - (20 [mm] × 2))), which may prevent the achievement of higher efficiency compared to the conventional configuration. As mentioned above, the distance d between coils is used as one of the comparison parameters in the comparative calculation. Therefore, if the distance d between coils in this embodiment is shorter than 27.8 mm, resulting in a vertically elongated cross-section, it may not be possible to generate a larger magnetic flux φ compared to the conventional configuration.

[0062] Thus, in the electric motor 10 (rotor 11) according to this embodiment, the coil space dimensions are optimized in order to achieve high efficiency while maintaining a compact size.

[0063] (summary) In conventional configurations, the rotor 21 has a rotor core 211n in which the field winding is installed in the circumferential direction A rather than the radial direction B. In this configuration, one of the magnetic poles of the second magnetic flux (longitudinal magnetic flux) generated in the rotor 21 is short-circuited, and only one of the magnetic poles, the N pole or the S pole, is used as the rotating magnetic field. In contrast, the electric motor 10 according to this embodiment has a rotor 11 in which the first winding W1n is installed in the rotor core 111n in the radial direction B rather than the circumferential direction A.

[0064] With this configuration, neither of the magnetic poles of the first magnetic flux (transverse magnetic flux) generated by the rotor 11 is short-circuited, and both the N and S poles can be used as a rotating magnetic field. As a result, the electric motor 10 according to this embodiment generates approximately 1.8 times the magnetic flux of a conventional configuration.

[0065] Furthermore, the electric motor 10 according to this embodiment has two rotor cores 111 n ,111 n+1 A single stator core 121n is positioned between them.

[0066] In this configuration, the magnetic flux, which was dispersed on both sides in the conventional configuration, is concentrated on one side, resulting in a strong rotating magnetic field.

[0067] As described above, the electric motor 10 (rotor 11) according to this embodiment can achieve higher efficiency than conventional configurations while maintaining a compact size.

[0068] Furthermore, in the rotor 11 according to this embodiment, the distance between coils is greater than in the conventional configuration, but the occupied cross-sectional area of ​​the first winding W1n is smaller than in the conventional configuration. As a result, the magnetomotive force F is small. However, in the electric motor 10 according to this embodiment, as described above, the rotor 11 is configured to utilize both sides of the generated magnetic flux as a rotating magnetic field, so it is possible to generate a larger magnetic flux than in the conventional configuration. Moreover, in the electric motor 10 according to this embodiment, since the magnetomotive force F of the rotor 11 is smaller than in the conventional configuration, the current supplied to the rotor 11 (magnetic field current) can be reduced, and higher efficiency can be achieved.

[0069] The technology of this disclosure is not limited to the embodiments and modifications described above, and various modifications are possible without departing from the gist of the invention. Furthermore, each configuration shown in the embodiments and modifications can be combined in any way. In other words, although the technology of this disclosure is described in accordance with the embodiments, it is understood that the technology of this disclosure is not limited to those embodiments or structures. The technology of this disclosure also includes various modifications and variations within the equivalent scope. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and conceptual range of the technology of this disclosure. [Explanation of symbols]

[0070] 10 electric motor; 11 Rotor; 111n rotor core; 12 stator; 121n stator core; WS1n (stator) coil space; WS2n (rotor) coil space; W1n, first winding; W2n second winding; 100 control systems.

Claims

1. A wound-field type electric motor (10), A rotor (11) is provided so as to be rotatable around a rotation axis (C) and has multiple rotor cores (111n) on which multiple first windings (W1n) are arranged, The rotor is provided with a stator (12) having a plurality of stator cores (121n) arranged in the circumferential direction (A) of the rotor, each of which has a plurality of second windings (W2n), The second winding is installed in the circumferential direction relative to the stator core and is configured to generate a second magnetic flux in the radial direction (B) of the rotor. The first winding is installed radially with respect to the rotor core and is configured to generate a first magnetic flux in the circumferential direction. An electric motor configured to form a rotating magnetic field by utilizing the magnetic poles on both sides of the first magnetic flux generated in the rotor.

2. The electric motor according to claim 1, wherein the two rotor cores are configured such that one stator core is positioned between them.

3. The rotor is, In order to install the first winding in the radial direction, a first coil space (HL) is arranged at a predetermined distance (d) apart in the radial direction. １ ) and the second coil space (HL ２ It is configured to have a pair of coil spaces (WS1n) including ) In the radial direction, the rotor core is located between the first coil space and the second coil space, and either the first coil space or the second coil space is configured to be located on the rotation axis side in the radial direction. The electric motor according to claim 1 or 2, wherein the first coil space and the second coil space are configured such that the cross-sectional area occupied by the first winding in each coil space has a maximum value determined based on the size of the coil space located on the rotation axis side in the radial direction.

4. A rotor for a wound-field electric motor, comprising a stator (12) having a plurality of stator cores (121n) provided in the circumferential direction (A) of the rotor (11), each of which has a plurality of second windings (W2n), wherein the second windings are installed in the circumferential direction relative to the stator core and are configured to generate a second magnetic flux in the radial direction (B) of the rotor, It has multiple rotor cores (111n) that are rotatably mounted around a rotation axis (C) and each of which has multiple first windings (W1n), The first winding is installed radially with respect to the rotor core and is configured to generate a first magnetic flux in the circumferential direction. A rotor in which the electric motor is provided to form a rotating magnetic field using the magnetic poles on both sides of the first magnetic flux generated in the rotor.

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