AXIAL GAP TYPE ROTATING ELECTRIC MACHINE

Abstract

Rotating electrical machine of the axial gap type, comprising: a rotating shaft (RS) that has an axis of rotation; two rotors (200, 300) that are rotatable around the axis of rotation of the rotating shaft (RS); a stator (100) whose two sides are opposite the two rotors (200, 300) with respect to an axial direction of the rotation axis of the rotating shaft (RS); a plurality of armature coils (11) arranged around the axis of rotation of the rotating shaft (RS) on the stator (100); a plurality of induction coils (21) and a plurality of excitation coils (22) arranged on each of the two rotors (200, 300) around the axis of rotation of the rotating shaft (RS); and Rectifier elements (23A, 23B) connected in such a way as to rectify an induced current generated by the plurality of induction coils (21) and then supply the rectified induced current to the plurality of excitation coils (22), wherein the number of slots (S) used for winding the plurality of induction coils (21) and the plurality of excitation coils (22) on each of the two rotors (200, 300) is in a ratio, i.e. a composition ratio (S / P), of 2 to 3 (S / P = 2 / 3) to the number of poles (P) of the stator (100) wound by the plurality of armature coils (11).

Description

[Technical field]

[0001] The present invention relates to a rotating electrical machine of the axial gap type, comprising a double rotor and utilizing excitation windings. [State of the art]

[0002] A rotating electric machine in which a rotor and a stator are opposite each other across a gap obtains a torque (i.e., a so-called reluctance torque, which arises from the phenomenon of reluctance) by causing a magnetic flux, generated in armature coils arranged on the stator side, to couple with the rotor side to form a magnetic circuit, and also uses a magnetic torque to assist the reluctance torque by arranging permanent magnets and / or excitation windings.

[0003] Moreover, because in such rotating electrical machines the magnetic flux generated by the armature coils includes spatial harmonic components, the magnetic flux of the spatial harmonics couples with the rotor side when the magnetic flux generated in the armature coils couples with the rotor side.

[0004] However, when the magnetic flux of the space harmonics couples with a permanent magnet, the magnetic force of the permanent magnet irreversibly decreases in magnitude due to a drop in magnetic coercivity caused by heat generated by an eddy current induced in the permanent magnet. This raises the problem that the magnetic force of the permanent magnets decreases in the type where the permanent magnets are integrated into the rotor side and coupled by the magnetic flux of the space harmonics, as described, for example, in JP 2006-187091A.

[0005] WO 2013 / 114286A2 discloses a rotating electrical machine. The machine comprises a rotating shaft, two rotors, a stator, a plurality of armature coils arranged around the axis of rotation of the rotating shaft on the stator, at least one induction coil, and a plurality of excitation coils arranged around the axis of rotation of the rotating shaft on each of the two rotors, as well as rectifier elements suitable for rectifying an induced current generated by the at least one induction coil and supplying the rectified induced current to the plurality of excitation coils.

[0006] JP 2014- 183 636 A discloses a reluctance motor which has a self-excitation function to achieve highly efficient rotation.

[0007] JP 2013- 38 918 A discloses a rotating electrical machine comprising a rotor arranged opposite a stator, in which N-poles and S-poles are alternately formed in the circumferential direction by the combination of a harmonic component contained in a magnetic field generated in the stator.

[0008] There is the fact that costs are rising because expensive magnets are being produced by increasing the additives of expensive heavy rare earth elements, such as dysprosium (Dy) and terbium (Tb) with their high magnetic coercivity, as is necessary to solve the problem. [Brief description of the invention][Technical problem statement]

[0009] It is therefore an object of the present invention to provide a rotating electric machine, without the need for the use of permanent magnets, which has a simple design, in order to generate a large torque without an external current supply, by effectively and efficiently utilizing the magnetic flux of the spatial harmonics generated by the armature coils. [Solution to the problem]

[0010] According to one embodiment of the present invention, a rotating electrical machine of the axial gap type is provided, comprising: a rotating shaft having an axis of rotation; two rotors rotatable about the axis of rotation of the rotating shaft; a stator, both sides of which are opposite the two rotors with respect to an axial direction of the axis of rotation of the rotating shaft; a plurality of armature coils arranged on the stator about the axis of rotation of the rotating shaft; a plurality of induction coils and a plurality of excitation coils arranged on each of the two rotors about the axis of rotation of the rotating shaft; and rectifier elements connected to rectify an induced current generated by the plurality of induction coils and then supply the rectified induced current to the plurality of excitation coils.The rotating electrical machine of the axial gap type according to the invention is characterized in that the number of slots (S) used for winding the plurality of induction coils and the plurality of excitation coils on each of the two rotors is in a ratio, i.e., a composition ratio S / P, of 2 to 3, S / P = 2 / 3, to the number of poles (P) of the stator that are wound by the plurality of armature coils.

[0011] In other words, a setup is realized in which the stator, on which the armature coils are arranged around the axis of rotation of the rotating shaft, is arranged between two rotors, its two axially spaced sides facing each of the two rotors; each of the two rotors comprises a plurality of induction coils and a plurality of excitation coils arranged around the axis of rotation of the rotating shaft; and the induced current generated by the induction coils is rectified by the rectifier elements and then supplied to the excitation coils, the number of slots (S) used for winding the plurality of induction coils and the plurality of excitation coils on each of the two rotors being in a ratio, i.e., a composition ratio S / P, of 2 to 3, S / P = 2 / 3. [Advantageous effects of the invention]

[0012] According to one embodiment of the present invention, the rotating electrical machine of the axial gap type is designed to arrange the rotors in one and the opposite axial direction opposite each of the two sides of the stator in order to cause a magnetic flux of the spatial harmonics generated in the armature coils on the stator to couple or link with each of the rotors opposite the two sides of the stator.

[0013] Therefore, it is possible to easily construct rotors with a symmetrical design, resulting in the generation of similar magnetic torque on both sides of the stator. Furthermore, without the need for permanent magnets, the rotating shaft can be driven integrally with a large magnetic torque, generated in the two rotors without an external power supply, by effectively and efficiently utilizing the magnetic flux of the spatial harmonics generated in the armature coils. [Brief description of the drawings] Fig. Figure 1 is a perspective exploded view of a rotating electrical machine according to an embodiment of the present invention. Fig. Figure 2 is a perspective view of a stator. Fig. Figure 3 is a perspective view of a rotor. Fig. Figure 4 is a simplified circuit diagram of induction coils and excitation coils connected to each other via diodes. Fig. 5A is a model diagram illustrating how armature coils, induction coils and excitation coils wind cores. Fig. Figure 5B is a diagram of magnetic forces illustrating the magnetic flux generated by and coupling the armature coils, induction coils, and excitation coils. Fig. Figure 6 is a representation of the magnetic flux characteristic, illustrating a magnetic flux and magnetic flux vectors of the magnetic flux of the third-order space harmonics within a rotational coordinate system. Fig. Figure 7 is a diagram of magnetic forces illustrating the magnetic flux generated by the armature coils, the induction coils and the excitation coils, coupling them together if a radial gap design without auxiliary poles is used. Fig. Figure 8 is a diagram of magnetic forces illustrating the magnetic flux generated by the armature coils, the induction coils and the excitation coils, coupling them together if a radial gap auxiliary pole design is used. Fig. Figure 9 is a graph illustrating a varying magnetic flux density with different degrees of rotation angle if coupling occurs across a gap from the armature coils, which are designed with concentrated or distributed winding. Fig. Figure 10 is a graph showing a magnetic flux density per order of the superimposed spatial harmonics, which is in the Fig. The 9 illustrated magnetic fluxes are included. Fig. Figure 11 is a graph illustrating a torque waveform for comparison with torque waveforms obtained by an interior permanent magnet synchronous motor (IPMSM), a radial gap type motor without auxiliary poles, and a radial gap type motor with auxiliary poles. [Description of the embodiments]

[0014] With reference to the drawings, embodiments of the present invention are described in detail below. Fig. Figures 1 to 11 are views illustrating a rotating axial gap type electrical machine according to an embodiment of the present invention.

[0015] Referring to Fig. 1 A rotating electric machine M has a power output suitable for powering, for example, a hybrid electric vehicle or an electric vehicle, because it comprises a stator 100 and two rotors 200, 300, whose outer shape in outline is a disk shape, and, as will be described later, no energy input into the rotors 200, 300 is necessary.

[0016] With regard to this rotating electric machine M, the two rotors 200, 300 are attached to a shaft (or a rotating shaft) RS extending through an axis of rotation, with a stator 100 arranged between them such that one of the rotors faces one side of the stator 100 across a gap, while the other faces the other side of the stator 100 across a different gap. The stator 100 rotatably supports the shaft RS, and the rotors 200, 300 are attached to this shaft RS. In other words, the rotating electric machine M is designed as a twin-rotor motor with an axial gap, in which the stator 100 is arranged between the two rotors 200, 300 such that they face each other in an axial direction along the shaft RS.

[0017] By making the stator 100, as in Fig. Figure 2 is equipped with many stator cores 15, each of which is a short rod with a trapezoidal cross-sectional profile, and armature coils 11, which are connected to three-phase current not shown, are wound around the stator cores 15 and arranged around the axis of rotation of the shaft RS.

[0018] The stator cores 15 are made of a high-permeability magnetic material and extend in directions parallel to the shaft RS. The armature coils 11 are divided into six (6) sets to provide six (6) poles, each set comprising the armature coils 11u, 11v, and 11w coupled to the three phases u, v, and w. In other words, the stator cores 15 are wound with concentrated winding such that six (6) poles are connected in parallel, each formed by a set of three armature coils 11u, 11v, and 11w.

[0019] Furthermore, 18 poles (i.e., the number of poles is 18) are arranged in the direction of rotation and equidistantly around the axis of rotation of the shaft RS, because the armature coils 11 are designed as wound coils whose central axes lie parallel to the shaft RS and which utilize the 18 stator slots 17, each of which lies between two adjacent stator cores 15. In short, the armature coils 11 are windings, each of which is wound around a central axis lying parallel to the axis of rotation of the rotating shaft RS and is arranged in the direction of rotation and equidistantly around the axis of rotation of the rotating shaft RS.

[0020] Each of these stator cores 15 is held by two disk-shaped supports 16, which are arranged in a position between the rotors 200, 300 on both sides of these rotors, spaced apart in the direction of rotation. Axially spaced end sections 15a of each of the stator cores 15 are inserted into one of the mounting holes 16a opening through one of the supports 16 and into one of the mounting holes 16a opening through the other support 16, in order to expose the axially spaced ends 15b. The supports 16 are made of a non-magnetic material so as not to interfere with the generation of high-quality magnetic circuits, and they allow the shaft RS to extend through them and to be rotatably supported by bearings (not shown) attached to their central sections.

[0021] Therefore, the stator cores 15 in the stator 100 are arranged such that the ends 15b of their end sections 15a are opposite the ends 25b of end sections 25a of the rotor cores (cores) 25 of the rotors 200, 300 described later, across gaps G. The stator 100 can provide an arrangement in which exciting the armature coils 11 with alternating current generates a magnetic flux to cause coupling or linking of the magnetic flux from the ends of the stator cores 15 to the ends 25b of the rotor cores of the rotors 200, 300.

[0022] As a result, the rotating electric machine M, using yokes 26 described later, causes the generation of magnetic circuits to redirect the magnetic flux that couples or links the rotor cores 25, which are arranged on both sides of the stator cores 15, causing each of the two rotors 200, 300, between which the stator 100 is arranged, to rotate relative to the stator 100 by means of a reluctance torque (i.e. a principal torque) generated by the phenomenon that the magnetic flux in each magnetic circuit follows the path of least resistance.

[0023] For this reason, it is necessary for the rotating electric machine M to apply the same amount of torque to one of the rotors 200, 300 as to the other in order to rotate the rotors 200, 300, which are attached to the common shaft RS as a unit, wherein in the unit the rotors 200, 300 are constructed in a symmetrical arrangement over the stator 100.

[0024] As a result, after the conversion of an supplied electricity into electrical energy, the rotating electric machine M can provide an output as mechanical energy from the shaft RS, which is coaxially rotatable with the rotors 200, 300 relative to the stator 100.

[0025] In the rotating electric machine M, the magnetic flux coupling the rotor cores 25 to the stator cores 15 contains superimposed spatial harmonics on a fundamental frequency. This enables the rotors 200, 300 to cause the built-in coils to generate an induced current, in order to provide an electromagnetic force by using the change in the magnetic flux density of the spatial harmonics contained in the coupling magnetic flux from the stator 100.

[0026] For more information regarding the above, it should be said that the magnetic flux generated by the armature coils 11 of the stator 100 contains spatial harmonics superimposed on the fundamental frequency, which varies with the fundamental frequency of the alternating current of the input electricity, and this flux couples with the rotors 200, 300 (i.e. to the rotor cores 25).

[0027] Because the spatial harmonics, which vary over time at frequencies different from the fundamental frequency of the fundamental oscillation, couple the rotor cores 25, the rotors 200, 300 can efficiently generate induced current by implementing coils around the rotor cores 25, without a separate power supply by coupling to an external power source. As a result, the spatial harmonics, which were previously considered a source of loss, are collected as self-excitation energy.

[0028] This is implemented in the rotating electric machine M by a winding around each of the rotor cores 25, wherein a free space between two adjacent rotor cores 25 is used as a rotor slot 27, wherein a coil wire of a first section and a coil wire of a second section, separated from each other along a longitudinal line of the core 25, form an induction coil 21 and an excitation coil 22, as shown in Fig. 3 shown.

[0029] In particular, each of the rotors 200, 300 is equipped with many rotor cores 25, each of which is a short rod with a trapezoidal cross-sectional profile, and each of the induction coils 21 and the excitation coil 22 which is not connected to any external current are wound around one of the rotor cores 25, so that the induction coils 21 and the excitation coils 22 are arranged around the axis of rotation of the shaft RS.

[0030] The rotor cores 25, which are formed from a highly permeable magnetic material, extend in directions parallel to the direction in which the shaft RS extends, and they are arranged in a circular direction, with each of the induction coils 21 and the associated excitation coils 22 sharing a rotor core 25 in vertical double sections or layers by concentrated winding.

[0031] In other words, twelve poles are arranged in the direction of rotation and equidistantly around the shaft RS by forming induction coils 21 and excitation coils 22 by means of windings whose central axes are parallel to the shaft RS, and by utilizing the twelve rotor slots 27, each of which lies between two adjacent rotor cores 25. In short, the induction coils 21 and the excitation coils 22 are formed by windings whose central axes are parallel to the axis of rotation of the rotating shaft, and they are arranged in the direction of rotation and equidistantly around the axis of rotation of the rotating shaft.

[0032] Therefore, the rotating electrical machine M is designed such that the number of slots S (S = 12) used for winding the induction coils 21 and the excitation coils 22 on each of the rotors 200, 300 is in a ratio, i.e. a composition ratio S / P, of 2 to 3 (S / P = 2 / 3) to the number of poles P (P = 18) of the stator 100 which are wound with the armature coils 11.

[0033] In each of the rotors 200, 300, the rotor cores 25 and a disk-shaped yoke 26 are integrally formed such that the side of each rotor core 25 furthest from the near side, where an end section 25a with its end surface 25b is opposite an end surface 15b of the adjacent stator core 15 via a gap G, forms an integral section of a surface face of the yoke 26. The yokes 26 are attached to the shaft RS to form a body, with the shaft RS passing through the central section of each yoke 26.

[0034] This setup enables the creation of closed magnetic circuits in which the magnetic flux that couples from the end face 15b of a stator core 15 with the end face 25b of a rotor core 25 flows through a bypass provided by the yoke 26 on the remote or rear side to this end face 25b to a point where it couples again with this end face 15b of another, different stator core 15, which is opposite an end face 25b of another, different rotor core 25.

[0035] Furthermore, each induction coil 21 is arranged on one side of the end section 25a, away from the yoke 26, of one of the rotor cores 25, in which it is effectively coupled by the magnetic flux of the space harmonics coming from one of the stator cores 15, while the associated excitation coil 22 is arranged on one side of a connecting section 25c near the yoke 26 of the rotor core 25.

[0036] This enables the rotating electric machine M to cause the magnetic flux to couple at high density across the narrow gap G from the end face 15b of the stator core 15 with the end face 25b of the rotor core 25, causing the induction coil 21 to generate induced current due to the space harmonics (i.e., the variation in the magnetic flux density of the space harmonics) contained in the magnetic flux, in order to supply this induced current to the associated excitation coil 22.

[0037] This excitation coil 22 can generate a magnetic flux (i.e., an electromagnetic force) during self-excitation using the induced current it receives from the induction coil 21 as an excitation current to cause this magnetic flux to couple the end face 15b of the stator core 15 from the end face 25b of the rotor core 25.

[0038] For this reason, the rotating electric machine M can provide assistance to drive the rotation of the rotors 200, 300 by obtaining a magnetic torque (i.e., an additional torque) in addition to the main torque generated due to the magnetic flux produced in the armature coil(s) 11.

[0039] In order to allow each of the rotor cores 25 to serve as an electromagnet for generating electromagnetic force by converting the alternating induced current generated by each of the induction coils 21 into direct current for supplying the converted direct current to the excitation coils 22, the induction coils 21 and the excitation coils 22 are arranged in a Fig. 4 illustrated closed circuit integrated to ultimately utilize the induced alternating current described above.

[0040] As in Fig. As illustrated in Figure 4, the induction coils 21 are wound around the rotor cores 25 by concentrated winding in the same direction, such that the portion of the induction coils 21 left in the same winding direction, which occupies every second of these (or the poles), is connected in series, and the remaining portion of the induction coils 21 is connected in series. In the rotating electric machine M, two sets of induction circuits 21A, 21B, one set comprising the induction coils 21a1-21a6, which occupy every second pole and are connected in series, and the other set comprising the induction coils 21b1-21b6, which are connected in series, are connected in parallel to each other by coupling one end of one of the two sets to one end of the other set via diodes (or rectifier elements) 23A, 23B.Although the connection of the induction coils 21, which occupy every second pole, is described as an example in series, to which the invention is not limited, the induction coils 21 can be divided in the direction of rotation into two sets for serial connection in each of these sets.

[0041] The excitation coils 22 are wound around the rotor cores 25 by means of concentrated winding in such a way that the winding direction is reversed from one pole to the next, and they are all connected in series. In this rotating electric machine M, an excitation circuit 22N, comprising the excitation coils 22a1-22a6, which are all connected in series, and a connection comprising the induction circuit 21A and the diode 23A are connected in parallel to allow the end sections 25a of the associated rotor cores 25 to function as N-poles, while another excitation circuit 22S, comprising the excitation coils 22b1-22b6, which are all connected in series, and a connection comprising the induction circuit 21B and the diode 23B are connected in parallel to allow the end sections 25a of the other rotor cores 25 to function as S-poles.

[0042] In other words, the induction coils 21 and the excitation coils 22 are integrated as excitation circuits 22N, 22S and induction coils 21A, 21B, together with the diodes 23A, 23B, into the closed circuit 29, which is not further connected to external circuits, such as an external current.

[0043] This circuit enables the rotating electric machine M to combine excitation DC currents, which are obtained by matching a half-wave rectification of the induced AC current generated by the armature coils 21 via the diodes 21A, 21B, and to supply the combined excitation DC currents to the excitation coils 22 connected in series. This causes a strong magnetic flux (or magnetic force) to be generated in the rotating electric machine M by effectively exciting each of the excitation coils 22 with the combined excitation DC currents, thereby enabling the excitation circuits 22N, 22S to function as electromagnets, with their N poles or S poles facing the stator cores of the stator 100.

[0044] Regarding the number of diodes 23A and 23B, if an increase in the number of poles is required, the number of diodes to be used is limited by fully connecting the excitation coils 21 and 22 in series. To avoid using a large number of diodes, diodes 23A and 23B are connected in such a way as to form not the predominant H-bridge full-wave rectifier circuit, but a star-point clamp full-wave rectifier circuit (rectifier elements). This is achieved by connecting the elements in such a way as to provide a phase difference of 180° between one input of the induced current and the other input of the induced current, in order to provide an output by performing half-wave rectification after converting the one input induced current.

[0045] As in Fig. As shown in Figure 1, in the rotating electric machine M, an end plate 30, made of an electrical insulating material, is attached to the rear of each of the rotors 200, 300 with respect to the stator 100, and a housing 32 and a circuit carrier 33 are attached to the end plate 30 for rotation as a single unit. The circuit carrier 33 is compact, with a connection structure or conductor track structure (not shown) that connects the induction coils 21 and the excitation coils 22 to form the closed circuit 29 (as shown in Figure 1). Fig. 4 shown) by connecting pin electrodes 23c of the diodes 23A, 23B, which are included inside the housing 32, to the connecting structure, and it is rotatable as a body with one of the rotors 200, 300.

[0046] The end plates 30 are designed in a disc shape which has the same diameter as the yokes 26 of the rotors 200, 300, and each of the end plates 30 is attached to the shaft RS in opposite contact with the rear of one of the rotors 200, 300 with respect to the rotor cores 25 in order to rotate with one of the rotors 200 or 300, wherein its retaining claws 30a, which are inserted into notches 26a, are formed from the rear of the yoke 26 inwards in order to effect an integral rotation of the end plates 30 and the yokes 26 without relative rotations to each other.

[0047] The switching carriers 33 are designed in a disc shape, having the same diameter as the end plates 30, and each switching carrier 33 is attached in a tight-fitting manner to the rear of one of the rotors 200, 300 with respect to the stator 100. The housing 32 is attached to the switching carrier 33 with one side in a tight-fitting manner, the pin electrodes 23c of the diodes 23A, 23B being brought out of the housing 32 and bent.

[0048] To efficiently generate induced current, the induction coils 21 and the excitation coils 22 are installed after rigorous identification of the magnetic paths of the spatial harmonics by performing a magnetic analysis. This allows for the efficient utilization of the third spatial harmonic contained in the magnetic flux that couples the end faces 25b of each of the rotor cores 25 to the end faces 15b of the stator core 15. Specifically, the rotating electrical machine M is constructed such that the number of slots S on each of the rotors 200, 300 is in a ratio, i.e., the ratio S / P, of 2 to 3 (S / P = 2 / 3) to the number of poles P of the stator 100, in order to efficiently utilize the 3fth spatial harmonic of the magnetic flux (f = 1, 2, 3, ...) within a rotating coordinate system.

[0049] In particular, it is difficult to cause the induction coil 21 to efficiently generate induced current when high-order spatial harmonics are used within the rotating coordinate system, because only waveforms (functions, oscillation profiles) indicate the propagation of vibrations near the surface of the end faces 25b of the rotor core 25. However, if the third spatial harmonic within the rotating coordinate system is fixed as an object to be recovered, the induction coil 21 is caused to actually generate induced current, since there is a pulsation with a shortened cycle due to a frequency higher than the fundamental frequency supplied to the armature coils 11. This provides rotation by efficiently recovering the energy loss of the spatial harmonics superimposed on the fundamental frequency.

[0050] Because the previously mentioned magnetic field analysis of the magnetic flux density indicates that the distribution of the magnetic flux density in a direction of rotation with a range of 360° in mechanical angle is distributed according to the composition ratio P / S, an additionally uneven distribution of the magnetic force acting on the stator 100 is detected.

[0051] Therefore, the rotating electric machine M provides a high-quality rotation of the rotors 200, 300 relative to the stator 100, with the rotors 200, 300 facing the stator 100, only by using a setup that satisfies the relationship that the assembly ratio S / P is equal to 2 / 3 and by coupling the magnetic flux with a uniform distribution over the entire 360° rotation at a mechanical angle.

[0052] This enables the rotating electric machine M to rotate with considerably reduced electromagnetic vibrations and exceptional quietness by performing spatial harmonics without leaving them as a loss and effectively recovering the energy loss.

[0053] Furthermore, the overall size of the rotating electrical machine M can be reduced by using a lumped winding design for the installation of the induction coils 21 and the excitation coils 22, because there is no need for a winding that spans more than one rotation. Additionally, the recoverable energy loss can be improved through efficient generation of induced current, due to the coupling of the lower-order third spatial harmonic and the reduction of copper losses on the primary side within the rotating coordinate system.

[0054] Furthermore, using the third spatial harmonic within the rotating coordinate system instead of the second spatial harmonic effectively generates induced current. Specifically, this means that the energy loss can be efficiently recovered because using the third spatial harmonic instead of the second causes an increase in the temporal variation of the magnetic flux, which in turn increases the amplitude of the induced current.

[0055] How easy from Fig. As can be seen in Figure 5A, the rotating electrical machine M causes the end surfaces 25b of the rotor cores 25 of the rotor 200 and the end surfaces 25b of the rotor cores 25 of the rotor 300 to be opposite each other across the gap G of the two end surfaces of the stator cores 15 of the stator 100, around which the armature coils 11 are wound, and it causes the induction coils 21 to wind around the end sections 25a, and it causes the excitation coils 22 to wind around the rotor cores 25 near the side of the yoke 26 (connecting sections 25c).

[0056] As in Fig. As shown in Figure 5B, the rotating electric machine M therefore causes the two rotors 200, 300 to rotate with respect to the stator 100 by causing the magnetic flux MF, which is generated by exciting the armature coils 11, to couple the stator cores 15 and the rotor cores 25 on both sides and to flow through bypasses provided by the yokes 26 to form a magnetic circuit. In addition, the superimposed spatial harmonics HF, which are contained in the magnetic flux MF, are caused to couple the rotor cores 25 on both sides from the stator cores 15, in order to be efficiently restored in the induction coils 25 at the end sections 25a by generating induced current, and the excitation current, which is given by the rectification of the induced current at the diodes 23A, 23B, is supplied to the excitation coils 22.The rotating electrical mechanism M causes the shaft RS to rotate with magnetic torque, which is generated by the coupling of the space harmonics HF in high flux density between the stator cores 15 and two rotor cores 25 on the two sides, as illustrated by the magnetic flux vectors V of the magnetic flux density of the third space harmonic HF, which couples the stator core 15 and with the two rotors, as for example in . Fig. 6 shown.

[0057] In the exemplary case of the radial gap-type rotating electric machine, in which a stator and a rotor are diametrically opposed across a gap, an inner and an outer rotor with different diameters are arranged such that the stator is positioned between them. Even in this configuration, it is desirable for each rotor to have windings to ensure a symmetrical arrangement; however, the inner and outer rotors differ considerably in the area through which they face each other radially and in the torque they exert on a shaft.

[0058] Because a radial gap-type design cannot provide a larger area for coupling spatial harmonics than an axial gap-type design, it is a disadvantage that spatial harmonics cannot be effectively utilized, even though the amount of spatial harmonics generated is increased by using centroidal windings in the armature coils 11. However, an axial gap-type rotating electrical machine M emits more leakage flux than the radial gap-type design, but the latter can effectively recover the leakage flux and therefore practically utilize spatial harmonics by effectively coupling them.

[0059] As in Fig. As shown in Figure 7, in the case of a radial-gap rotating electric machine, an end face 45b of each rotor core 45 faces an end face 35b on one side of the stator core 35, which is wound by an armature coil 31, via a gap G. Consequently, this setup cannot efficiently restore the space harmonics HF contained in the magnetic flux MF generated by exciting the armature coils 31, making it difficult to generate a large magnetic torque and allowing core loss at the side of the yoke 46 to increase it even further than in the axial-gap twin-rotor rotating electric machine M.

[0060] To restore more space harmonics (HF) even in a rotating electrical machine of the radial gap type, it is further necessary, as described in Fig. As shown in Figure 8, it was also considered to arrange an auxiliary pole core 48 for recovery within a rotor slot 47 between two rotor cores 45 and to wind this with an induction coil 49. However, this setup cannot provide an increase in magnetic torque because it only recovers high-frequency spatial harmonics emanating from one side of the stator core 35, and therefore the obtained magnetic torque is less than the level of magnetic torque provided by the rotating electric machine M. Additionally, this setup reduces the leg ratio of the rotor side because an auxiliary pole core 48, which couples with the magnetic flux, is arranged between the rotor cores 45.

[0061] Furthermore, the rotating electrical machine M arranges armature coils 11, induction coils and excitation coils 22, all wound by concentrated winding, on the stator 100 and the rotors 200, 300, however the concentrated winding can be replaced by a distributed winding. Fig. Figure 9 shows the solid line of the magnetic flux waveform of the magnetic flux density coupling the end face 25b of the rotor core 25 with the end face 15b of the stator core 15 in the case of the concentrated winding, compared to the dashed line of the magnetic flux waveform of the magnetic flux density in the case of the distributed winding. As can be easily seen from the in Fig. As can be seen from the results of the electromagnetic field analysis of the magnetic flux waveforms shown in Figure 10, more second spatial harmonics within the static coordinate system, i.e., more third spatial harmonics within the rotatable coordinate system, are present in the case of the concentrated winding than in the case of the distributed winding. From this result, it follows that selecting the concentrated winding is advantageous over selecting the distributed winding, since in the case of the concentrated winding, more spatial harmonics penetrate deep inwards from the end face 25b of the rotor core 25 to cause the induction coil 21 to generate an induced current, which is rectified to the excitation current to be supplied to the excitation coils 22, than in the case of the distributed winding.

[0062] As in Fig. As shown in Figure 11, the rotating electric machine M is started by applying alternating current to the armature coils 11 of the stator 100, which is arranged between the two rotors 200, 300, and can drive the shaft RS to rotation with a high torque, as illustrated by the solid curve in the case of an axial-gap twin-rotor type. As shown by the line in Fig. Figure 11, which is drawn as a single-dot dash, illustrates the construction of the radial gap type without auxiliary poles, as in Fig. 7 shown, and the structure, illustrated by the line in Fig. 11, which is drawn as a two-dot dash dashed line, of the radial gap type with auxiliary poles, as shown in Fig. 8, not providing as much torque as the rotating electric machine M. As indicated by the dashed line in Fig.As illustrated in Figure 11, the IPMSM (internal permanent magnet synchronous motor) cannot generate as large a magnetic torque as the rotating electric machine M.

[0063] As can be seen from the preceding description, according to the present embodiment it is possible to effectively couple spatial harmonics contained in the main magnetic flux generated by the armature coils 11 with the induction coils 21, because the armature coils 11, the induction coils 21 and the excitation coils 22 are arranged on the stator 100 and on each of the rotors 200, 300 around the axis of rotation of the shaft RS. The induced current generated by the induction coils 21 is then efficiently supplied to the excitation coils 22 as an excitation current.

[0064] Without the need for the use of permanent magnets, thus eliminating a drop in magnetic force resulting from heated permanent magnets due to space harmonics, and without the supply of external current, a reluctance torque and a magnetic torque are therefore applied uniformly to the rotors 200, 300 to drive the shaft RS.

[0065] As other forms of the present invention, the formation of the stator cores 15 and the rotor cores 25 is not limited to forming them from laminated structures by layering electromagnetic steel sheets; it is possible, for example, to use so-called cores made of soft magnetic composite materials (SMC cores, Softmagnetic Composite cores), which can be described as powder magnetic cores manufactured by compression molding of iron powder and heat treatment of soft magnetic composite materials (SMCs) made of ferromagnetic powder particles, such as aluminum conductors or iron powder particles encased in an electrically insulating film.

[0066] Additionally, the rotating electric machine M can be constructed as a hybrid type by arranging permanent magnets by adding them to the rotors 200, 300, or a magnetic torque can be obtained by a machine of the hybrid excitation type.

[0067] The rectifier elements are not limited to diodes 23A, 23B, and other semiconductor elements, such as switching elements, can be used as rectifier elements. These are not limited to the types included within the housing 32, and they can be integrated within the rotors 200, 300.

[0068] The use of the rotating electric machine M is not limited to automotive applications and it is possible, for example, to use it in wind turbines or as a drive for machine tools.

[0069] Although embodiments of the present invention have been described, it is obvious that a person skilled in the art can make modifications without departing from the scope of the present invention. All such modifications and their equivalents are to be encompassed by the appended claims. [List of reference symbols] 11, 11u to 11w armature coil (winding) 15 Stator core 16 bracket 17 Stator slot 21, 21a1 to 21a6, 21b1 to 21b6 Induction coil (winding) 22, 22a1 to 22a6, 22b1 to 22b6 Excitation coil (winding) 23A, 23B Diode (rectifier element) 25 Rotor core (core) 26 yoke 27 Rotor slot 29 closed circuit 30 End plate 33 circuit carriers 32 cases 100 Stator 200, 300 Rotor G gap RF Magnetic flux of spatial harmonics M rotating electric machine MF magnetic flux RS shaft (rotating shaft)

Claims

[1] Rotating electrical machine of the axial gap type, comprising: a rotating shaft (RS) that has an axis of rotation; two rotors (200, 300) that are rotatable around the axis of rotation of the rotating shaft (RS); a stator (100) whose two sides are opposite the two rotors (200, 300) with respect to an axial direction of the rotation axis of the rotating shaft (RS); a plurality of armature coils (11) arranged around the axis of rotation of the rotating shaft (RS) on the stator (100); a plurality of induction coils (21) and a plurality of excitation coils (22) arranged on each of the two rotors (200, 300) around the axis of rotation of the rotating shaft (RS); and Rectifier elements (23A, 23B) connected in such a way as to rectify an induced current generated by the plurality of induction coils (21) and then supply the rectified induced current to the plurality of excitation coils (22), wherein the number of slots (S) used for winding the plurality of induction coils (21) and the plurality of excitation coils (22) on each of the two rotors (200, 300) is in a ratio, i.e. a composition ratio (S / P), of 2 to 3 (S / P = 2 / 3) to the number of poles (P) of the stator (100) wound by the plurality of armature coils (11). [2] Rotating electric machine of the axial gap type according to claim 1, wherein the plurality of armature coils (11) of the stator (100), the plurality of induction coils (21) and the plurality of excitation coils (22) on each of the two rotors (200, 300) are designed as windings whose central axes are parallel to the axis of rotation of the rotating shaft (RS), the windings are arranged in the direction of rotation and equidistant around the axis of rotation of the rotating shaft (RS). [3] Rotating electric machine of the axial gap type according to one of the preceding claims 1 or 2, wherein the plurality of induction coils (21) and the plurality of excitation coils (22) are wound around a plurality of cores that extend parallel to the axis of rotation of the rotating shaft (RS), and Each of the multiple induction coils (21) is wound around one of the multiple cores at a position close to the stator (100), and each of the multiple excitation coils (22) is wound around this one core (25) at a position farther from the stator (100). [4] Rotating electrical machine of the axial gap type according to any one of the preceding claims 1 to 3, wherein the rectifier elements (23A, 23B) are integrated in closed circuits comprising the plurality of induction coils (21) and the plurality of excitation coils (22) and which are integrally rotatable with the two rotors (200, 300). [5] Rotating electrical machine of the axial gap type, comprising: a rotating shaft (RS) that has an axis of rotation; two rotors (200, 300) rotatable about the axis of rotation of the rotating shaft (RS), each rotor having a plurality of cores extending parallel to the axis of rotation of the rotating shaft (RS); a stator (100) whose two sides are opposite the two rotors (200, 300) with respect to an axial direction of the rotation axis of the rotating shaft (RS); a plurality of armature coils (11) arranged around the axis of rotation of the rotating shaft (RS) on the stator (100); a plurality of induction coils (21) and a plurality of excitation coils (22) arranged on each of the two rotors (200, 300) around the axis of rotation of the rotating shaft (RS); and Rectifier elements (23A, 23B) connected in such a way as to rectify an induced current generated by the plurality of induction coils (21) and then supply the rectified induced current to the plurality of excitation coils (22), wherein the plurality of induction coils (21) and the plurality of excitation coils (22) are wound around the plurality of cores, and wherein each of the plurality of induction coils (21) is wound around one of the plurality of cores at a position close to the stator (100) in the axial direction and each of the plurality of excitation coils (22) is wound around this one core (25) is wound in a position located axially away from the stator (100).

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