WO2018142653A1 - Radial gap rotary electric machine - Google Patents

Abstract

The present invention according to one aspect has a configuration, in which six phase coils in two concentratedly wound three-phase coils in a tandem motor are arranged in the circumferential direction by at least either a pole number-doubling arrangement that doubles the number of poles or a phase number-doubling arrangement that doubles the number of phases. The present invention according to another aspect has a configuration, in which an insulating conductor of a distributedly wound stator coil in a tandem motor alternately penetrates a slot of a front stator core and a slot of a rear stator core. This insulating conductor is bent in the circumferential direction between the front stator core and the rear stator core. The present invention according to still another aspect has a configuration, in which a front motor mainly generates a magnetic torque and a rear rotor core mainly generates a reluctance torque. The present invention according to a further aspect has a configuration, in which a front stator core and a rear stator core each are composed of a T-shaped core segment. Preferably, a housing has a diecast fitting part that mechanically joins to a wedge part of the core segment.

Description

Radial gap type rotating electrical machine

The present invention relates to a radial gap type rotating electrical machine including a motor or a generator, and more particularly to a tandem radial gap type rotating electrical machine.

FIG. 1 shows an example of a conventional concentrated winding synchronous motor. The stator core has 1.5 stator poles 10 per pole of the rotor 11. The phase current IU flowing through the phase coil 1 U forms a phase magnetic field U in the stator pole 10. The phase current IV flowing through the phase coil 1 V forms a phase magnetic field V in the stator pole 10. The phase current IW flowing through the phase coil 1 W forms a phase magnetic field W in the stator pole 10. FIG. 2 shows the vectors of the phase magnetic fields U, V, W. However, a concentrated winding having only three phase magnetic field vectors per 360 degrees of electrical angle has the problem of increasing torque ripple and vibration.

FIG. 3 shows an example of a conventional distributed winding. The stator core has six teeth 10 per 360 electrical degrees. The phase currents IU, IV, and IW form the six phase magnetic field vectors U, -V, W, -U, V, and W shown in FIG. 4 in the electric angle range of 360 degrees. Distributed winding with long coil ends increases copper loss.

FIG. 5 shows another example of conventional distributed winding. The stator core has six teeth 10 per 180 electrical degrees. FIG. 6 shows an arrangement example of the phase coils 1U, 1V, and 1W. Phase current IU flows through phase coil 1U, phase current IV flows through phase coil 1V, and phase current IW flows through phase coil 1W. The stator coil is wound at a short pitch. FIG. 7 shows twelve slot current vectors formed in the electrical angle range of 360 degrees. This slot current means a vector sum of a plurality of phase currents flowing through one slot.

Patent Documents 1 and 2 disclose a tandem motor in which two motors are arranged in the axial direction. In a conventional tandem motor, two stator coils wound separately on different stator cores are generally connected to DC power supplies having different voltages.

U.S.Patent No.5,592,039 U.S.Patent No.7,397,157

A traction motor provided under the floor for an electric vehicle tends to adopt a long motor shape having a long axial length. However, long motors have the disadvantage of increased copper loss.

In addition, long motors have stator coil cooling problems. When the long motor is driven in the low speed and large torque region, the stator coil causes a serious temperature rise in the central portion of the stator core far from the coil end. Therefore, in the long motor type traction motor, cooling of the central portion of the stator coil in the axial direction becomes an important problem.

The reduction in the magnetic pole cross-sectional area of the stator pole reduces the distance of one turn of the stator coil called the turn length. However, this reduction in the cross-sectional area of the stator pole reduces the motor torque. For this reason, the increase in the stator current for maintaining the torque increases the copper loss. Eventually, copper loss reduction needs to be realized without reducing the cross-sectional area of the stator pole.

After all, the important indexes related to the copper loss reduction are the magnetic path cross-sectional area (Sfe) of the stator pole, the turn length (Lc) of the coil conductor, and the cross-sectional area (Scu) of the coil conductor. After all, reduction of the ratio (Lc / (Scu × Sfe)) is important in reducing copper loss. In the following, this ratio is called the resistance ratio. For example, in an operating condition where copper loss accounts for 50% of motor loss, a 10% reduction in resistance ratio results in a 5% efficiency improvement.

Reducing manufacturing costs is another important issue for traction motors for electric vehicles. The huge spread of electric vehicles results in an increase in the price of permanent magnet motors. An induction motor is more advantageous than a permanent magnet motor in terms of suppression of counter electromotive force in a high speed region and manufacturing cost. However, induction motors have inherently higher copper losses than permanent magnet motors. Furthermore, an increase in copper loss in the large current region causes overheating problems of the stator coil.

One object of the present invention is to provide a radial gap type rotating electrical machine capable of reducing copper loss and vibration. Another object of the present invention is to provide a radial gap type rotating electrical machine capable of suppressing a temperature rise of a stator coil.

According to one aspect of the present invention, the tandem motor has two concentrated winding three-phase coils. According to the stator pole arrangement of the tandem motor called tandem concentrated winding, at least one of a double pole arrangement capable of doubling the number of poles and a double phase arrangement capable of doubling the number of phases is employed. In the double pole arrangement, the electrical angle of 360 degrees corresponds to 1.5 times the front salient pole pitch, and the stator coil generates a three-phase electromotive force. In the double phase arrangement, the electrical angle of 360 degrees corresponds to three times the front salient pole pitch, and the stator coil generates a symmetrical six-phase electromotive force. Thereby, torque ripple and vibration are reduced. Further, this tandem concentrated winding has a copper loss reducing effect and a temperature rise suppressing effect which are superior to conventional distributed winding or conventional concentrated winding having the same output.

In one aspect, the magnetic pole surface of the front salient pole and the magnetic pole surface of the rear salient pole overlap in the circumferential direction. This reduces torque ripple and improves magnet utilization. In another aspect, the front salient pole is shifted by a half salient pole pitch in the circumferential direction compared to the rear salient pole. Thereby, torque ripple is reduced. In another aspect, an induction motor employing tandem concentrated winding has a common conductor bar that passes through the front rotor core and the rear rotor core in turn. According to this tandem induction motor, harmonics are reduced.

In another embodiment, the two three-phase coils are connected to a common three-phase AC power source. This three-phase AC power supply can be constituted by one three-phase inverter or a commercial three-phase power supply. In another embodiment, the two three-phase coils are separately connected to the two three-phase inverters. In another embodiment, the two three-phase inverters switch between the double phase arrangement and the double pole arrangement by changing the phase of the six-phase voltage applied to the two three-phase coils. This switching technique is called a pole number switching technique.

In another embodiment, two three-phase inverters fix two phase voltages having opposite phases to an intermediate voltage, and add a predetermined bias voltage to the remaining four phase voltages. Thereby, the number of turns of the stator coil is switched equivalently. This switching technique is called a winding number switching technique. In another aspect, the two three-phase inverters perform a four-phase mode. According to this four-phase mode, two three-phase inverters perform two-phase modulation with opposite phases. Thereby, inverter loss can be reduced while suppressing leakage current.

In another embodiment, the polarity of either of the two rotor cores is inverted by a polarity inversion circuit. In another aspect, the polarity inversion circuit switches only the direction of the field current supplied to one of the two field coils. In another aspect, the polarity reversing circuit provides a reversible field current to a diode circuit for fixing the direction of the field current flowing through one of the two field coils.

In another aspect, the stator coil has an independent three-phase coil consisting of three phase coils that are separately connected in series to each phase coil of the star-connected three-phase coil. In another aspect, the star-connected three-phase coil and the independent three-phase coil are connected in series to the first power converter and connected in parallel to the second power converter. Preferably, the first power converter comprises a three-phase inverter, and the second power converter comprises a three-phase rectifier. Preferably, the independent three-phase coil has more turns than the star connected three-phase coil.

According to another aspect of the present invention, the distributed winding stator coil of the tandem motor has insulated conductors that alternately pass through the in-phase slots of the front stator core and the out-of-phase slots of the rear stator core. Further, the insulated conductor is bent in the circumferential direction in an idle space between the front stator core and the rear stator core. According to the tandem distributed winding, the coil end is simplified and the stator coil can be easily cooled. Preferably, the rear stator core has a longer axial length than the front stator core. Thereby, torque ripple is reduced. This tandem distributed winding can use the technique of each aspect of the tandem concentrated winding described above.

According to another aspect of the present invention, the front motor of the tandem motor mainly generates magnet torque, and the rear motor mainly generates synchronous reluctance torque. This tandem motor is called a tandem composite synchronous motor. Preferably, the relative angle between the front rotor core and the rear rotor core is set to a value at which the front motor and the rear motor can respectively generate substantially maximum torque. This tandem composite synchronous motor can realize low copper loss by increasing electromotive force. Furthermore, this tandem composite synchronous motor can employ the technology of each aspect of the tandem concentrated winding described above.

According to another aspect of the invention, the tandem concentrated winding stator core consists of aligned core segments. Each core segment has a linear yoke portion projecting substantially tangentially from the stator pole. Thereby, copper loss is reduced. Further, automation of the winding work is facilitated.

According to another aspect of the present invention, a stator core of an inner rotor radial gap motor including a tandem motor is composed of a number of core segments arranged in an annular shape. Each core segment has a yoke portion extending linearly from the stator pole in the tangential direction. Thereby, the slot cross-sectional area can be enlarged. Preferably, each core segment has a wedge for housing fitting. The housing has a die-cast fitting portion that is in close contact with the wedge portion. Thereby, the housing can suppress the relative vibration between core segments satisfactorily. Further, relative vibration between the front rotor core and the rear stator core is also suppressed in the tandem concentrated winding.

FIG. 1 is a developed view showing a conventional concentrated winding. FIG. 2 is a vector diagram showing three phase magnetic field vectors of concentrated winding. FIG. 3 is a development view showing one conventional distributed winding. FIG. 4 is a vector diagram showing the six phase magnetic field vectors of the distributed winding shown in FIG. FIG. 5 is a developed view showing another conventional distributed winding. FIG. 6 is a wiring diagram of the distributed winding shown in FIG. FIG. 7 is a vector diagram showing 12 phase magnetic field vectors of the distributed winding shown in FIG. FIG. 8 is an axial sectional view showing the tandem concentrated winding induction motor of the first embodiment. FIG. 9 is a block circuit diagram showing a double inverter type tandem motor drive circuit. FIG. 10 is an axial sectional view showing a saddle-shaped rotor of the tandem motor. FIG. 11 is a side view of the saddle type rotor. FIG. 12 is an axial cross-sectional view showing another saddle coil. FIG. 13 is a side view showing the saddle coil shown in FIG. FIG. 14 is a side view showing the three-phase inverter shown in FIG. 15 is an axial sectional view of the three-phase inverter shown in FIG. FIG. 16 is a side view showing the front stator in the double pole. FIG. 17 is a side view showing the rear stator in the double pole arrangement. FIG. 18 is a development view showing the phase current distribution in the double pole arrangement. FIG. 19 is a vector diagram showing phase magnetic field vectors in a double pole arrangement. FIG. 20 is a side view showing the front stator in the double phase arrangement. FIG. 21 is a side view showing the rear stator in the double phase arrangement. FIG. 22 is a development view showing the phase current distribution in the double phase arrangement. FIG. 23 is a vector diagram showing phase magnetic field vectors in the double phase arrangement. FIG. 24 is a timing chart showing intermediate potential leg switching timing in the series mode. FIG. 25 is a vector diagram showing a correction phase voltage vector in one phase period of the series mode. FIG. 26 is a vector diagram showing a corrected phase voltage vector in another phase period of the series mode. FIG. 27 is a vector diagram showing a correction phase voltage vector in another phase period of the series mode. FIG. 28 is a sectional view in the axial direction showing the tandem concentrated winding synchronous motor of the second embodiment. FIG. 29 is a block circuit diagram showing a single inverter type tandem motor drive circuit. FIG. 30 is a development view showing a tandem stator in a double pole arrangement. FIG. 31 is a development view showing the tandem stator in the double phase arrangement. FIG. 32 is an axial sectional view showing a tandem concentrated winding starter generator according to a third embodiment. FIG. 33 is a schematic diagram showing the rotor magnetic pole arrangement of this tandem starter generator. FIG. 34 is a wiring diagram showing the rotor circuit. FIG. 35 is a side view showing a terminal ring in which a diode is built. FIG. 36 is a developed view showing the back electromotive force of each phase in the engine start mode. FIG. 37 is a development view showing the generated voltage of each phase in the power generation mode. FIG. 38 is a wiring diagram showing a power converter of the tandem starter generator. FIG. 39 is a vector diagram showing the generated voltage in the power generation mode. FIG. 40 is a vector diagram showing the back electromotive force in the engine start mode. FIG. 41 is a schematic diagram showing an alignment process of the split core type stator core of the fourth embodiment. FIG. 42 is a radial sectional view showing a die-casting process of the split core type stator core. FIG. 43 is an axial cross-sectional view showing this die casting process. FIG. 44 is a side view showing a core segment of a split core type stator core. FIG. 45 is a side view showing a split-core stator core according to a modified embodiment. 46 is an axial sectional view of the stator core shown in FIG. FIG. 47 is a side view showing a concentrated winding core segment as a comparative example. FIG. 48 is an axial cross-sectional view showing a tandem distributed winding of the fifth embodiment. 49 is a developed view showing the front stator shown in FIG. FIG. 50 is a development view showing the rear stator shown in FIG. FIG. 51 is a vector diagram showing phase current vectors of this tandem motor. FIG. 52 is a wiring diagram showing a stator coil of the tandem motor. FIG. 53 is another wiring diagram showing this stator coil. FIG. 54 is a schematic diagram showing a stator pole arrangement of tandem distributed winding. FIG. 55 is a schematic diagram showing a conventional distributed winding stator pole arrangement as a comparative example. FIG. 56 is an axial sectional view showing a tandem composite synchronous motor of the sixth embodiment. FIG. 57 is a vector diagram showing one phase difference between two rotor cores. FIG. 58 is a vector diagram showing another phase difference between two rotor cores.

A preferred embodiment of an inner rotor radial gap rotating electrical machine according to the present invention will be described with reference to the drawings. This rotating electric machine consisting of two motors substantially arranged in tandem is abbreviated as a tandem motor. The first embodiment relates to a tandem concentrated winding induction motor. The second embodiment relates to a tandem concentrated winding synchronous motor. The third embodiment relates to a tandem concentrated winding starter generator. The fourth embodiment relates to a split core type tandem concentrated winding motor. The fifth embodiment relates to a tandem distributed winding motor. The sixth embodiment relates to a tandem composite synchronous motor.

First Embodiment FIG. 8 shows a tandem concentrated winding induction motor. The front motor 7 and the rear motor 8 housed in the housing 5 are arranged in tandem in the axial direction of the common rotary shaft 12. The front motor 7 has a front stator core 71, a three-phase coil 1, a front rotor core 73, and a common saddle coil 9. The front stator core 71 is fixed to the housing 5. The three-phase coil 1 is wound around the front stator core 71. The front rotor core 73 is fixed to the rotating shaft 12. The rear motor 8 has a rear stator core 81, a three-phase coil 2, a rear rotor core 83, and a common saddle coil 9. The rear stator core 81 is fixed to the housing 5. Three-phase coil 2 is wound around rear stator core 81. The rear rotor core 83 is fixed to the rotating shaft 12.

The stator cores 71 and 81 sandwich a nonmagnetic spacer 15 fixed to the housing 5. The rotor cores 73 and 83 sandwich a nonmagnetic spacer 16 fixed to the rotating shaft 12. The annular spacers 15 and 16 can be omitted. Each one coil end of the three- phase coils 1 and 2 is accommodated in an idle space formed by the spacers 15 and 16. The three-phase coil 1 is connected to a three-phase inverter 3 fixed to the front end wall of the housing 5. The three-phase coil 2 is connected to a three-phase inverter 4 fixed to the rear end wall of the housing 5.

FIG. 9 shows a drive circuit for this tandem induction motor. This circuit with two three- phase inverters 3 and 4 is called a double inverter circuit. Inverter 3 consists of three legs 3U, 3V, and 3W. The inverter 4 is composed of three legs 4U, 4V, and 4W. The controller 100 controls the inverters 3 and 4. The three-phase coil 1 comprises three phase coils 1U, 1V, and 1W connected in a star shape (Wye). The three-phase coil 2 comprises three phase coils 2U, 2V, and 2W connected in a star shape (Wye). The leg 3U applies a phase voltage V1 to the phase coil 1U and supplies a phase current I1. The leg 3V applies a phase voltage V2 to the phase coil 1V and supplies a phase current I2. The leg 3W applies the phase voltage V3 to the phase coil 1W and supplies the phase current I3. Similarly, the leg 4U applies a phase voltage V4 to the phase coil 2U and supplies a phase current I4. The leg 4V applies the phase voltage V5 to the phase coil 2V and supplies the phase current I5. The leg 4W applies a phase voltage V6 to the phase coil 2W and supplies a phase current I6. The electrical angle between any two of the three phase currents I1-I3 is 120 degrees. The electrical angle between any two of the three phase currents I4-I6 is 120 degrees.

FIG. 10 is an axial sectional view showing a saddle rotor, and FIG. 11 is a side view of the saddle rotor. The saddle-shaped coil 9 formed by die casting is composed of a large number of conductor bars 91 and two end rings 92. Each conductor bar 91 extending substantially in the axial direction is separately accommodated in each slot of the rotor cores 73 and 83. Each conductor bar 91 passes through one slot of each of the rotor cores 73 and 83 in order. One end of the annular end ring 92 is connected to the front end of the conductor bar 91, and the other is connected to the rear end of the conductor bar 91. Each end ring 92 has wings 93 formed radially. The rotating wing part 93 forms an air flow indicated by an arrow.

Another embodiment of the saddle coil 9 will be described with reference to FIGS. FIG. 12 is an axial sectional view showing a part of the saddle coil 9. The saddle-shaped coil 9 includes a coil portion 9A fixed to the front rotor core 73 by die casting and a coil portion 9B fixed to the rear rotor core 83 by another die casting. The coil portion 9A includes a conductor bar 91A and a connection end portion 95A. The conductor bar 91A is inserted into the slot of the rotor core 73. FIG. 13 is a side view showing the connecting end portion 95A. Each connection end 95A extends radially inward from the conductor bar 91A along the rear end surface of the rotor core 73. Similarly, the coil portion 9B includes a conductor bar 91B and a connection end portion 95B. The conductor bar 91B is inserted into the slot of the rotor core 83. The connecting end portion 95B extends radially inward from the conductor bar 91B along the front end surface of the rotor core 83. Each pair of connection end portions 95A and 95B having the same shape is in close contact with each other in the idle space between the rotor cores 73 and 83. The joint 96 of the connection ends 95A and 95B is welded. Thereby, manufacture of the saddle-shaped coil 9 becomes easy.

FIG. 14 is a side view showing the three-phase inverter 3 fixed to the front end wall of the housing 5. FIG. 15 is an axial sectional view showing the leg 3U of the three-phase inverter 3. As shown in FIG. The three legs 3U, 3V, and 3W of the inverter 3 are arranged radially around the rotating shaft 12. The illustration of the free wheel diode is omitted. The upper arm transistors 3UU, 3VU, and 3WU are disposed outside the lower arm transistors 3UL, 3VL, and 3WL in the radial direction. The upper arm transistors 3UU, 3VU, and 3WU are sandwiched between an annular copper plate 501 and an L-shaped output terminal 503-505. Similarly, the lower arm transistors 3UL, 3VL, and 3WL are sandwiched between an annular copper plate 502 and output terminals 503-505. The output terminals 503-505 extend into the housing 5 through holes in the housing 5. The copper plates 501 and 502 are fixed to the front end wall of the housing 5 through an insulating sheet. The copper plate 501 is connected to the positive electrode of the DC power source, and the copper plate 502 is connected to the negative electrode of the DC power source. The three-phase inverter 4 has the same structure as the three-phase inverter 3.

This tandem induction motor employs a pole number switching technique for switching the number of stator poles. This pole number switching technique includes a double pole mode in which the number of stator poles is doubled and a double phase mode in which the number of stator phases is doubled. The double pole mode is described with reference to FIGS. FIG. 16 is a side view showing the front stator core 71. The front stator core 71 has six stator poles 72 projecting radially inward from an annular yoke 75. The stator pole 72 is called a front salient pole. Each stator pole 72 has a magnetic pole surface 74 that faces the front rotor core 73. Three phase coils 1U, 1V, and 1W of the three-phase coil 1 are concentrated and wound around six stator poles 72 in order. The mechanical angle between the two stator poles 72 adjacent to each other is 60 degrees.

FIG. 17 is a side view showing the rear stator core 81. The rear stator core 81 has six stator poles 82 projecting radially inward from an annular yoke 85. The stator pole 82 is called a rear salient pole. Each stator pole 82 has a magnetic pole surface 84 that faces the rear rotor core 83. Three phase coils 2U, 2V, and 2W of the three-phase coil 2 are concentrated and wound around six stator poles 82 in order. The mechanical angle between the two stator poles 82 adjacent to each other is 60 degrees.

The stator pole 82 is shifted in the circumferential direction by a mechanical angle of 30 degrees corresponding to a half pole pitch with respect to the stator pole 72. The skew angle of each conductor bar 91 is zero. When the conductor bar 91 has a predetermined skew angle, the stator pole 72 can be shifted in the circumferential direction compared to the stator pole 82.

FIG. 18 is a circumferential development showing the arrangement of the magnetic pole surfaces 74 and 84 in the double pole mode. This arrangement is called a double pole arrangement. The dashed lines shown in the pole faces 74 and 84 indicate the minimum circumferential width of the stator poles 72 and 82. The phase coil 2V is arranged at an intermediate position between the phase coils 1U and 1W in the circumferential direction. The phase coil 2U is arranged at an intermediate position between the phase coils 1W and 1V in the circumferential direction. The phase coil 2W is arranged at an intermediate position between the phase coils 1V and 1U in the circumferential direction. In other words, the circumferential distance between the two phase coils of the three- phase coils 1 and 2 that are in phase with each other is equal to 1.5 times the stator pole pitch.

The phase magnetic fields U, V, W formed by the three- phase coils 1 and 2 on the magnetic pole surfaces 74 and 84 form a rotating magnetic field. Therefore, the electrical angle of this rotating magnetic field of 360 degrees corresponds to 1.5 times the stator pole pitch. Each of the magnetic pole surfaces 74 and 84 has a circumferential width substantially corresponding to an electrical angle of 180 degrees. A slot between two magnetic pole faces 74 adjacent to each other has a circumferential width substantially corresponding to an electrical angle of 60 degrees.

The current IU flowing through the phase coil 1 U forms a phase magnetic field U on the magnetic pole surface 74. The phase current IW flowing through the phase coil 1 W forms a phase magnetic field W on the magnetic pole surface 74. The phase current IV flowing through the phase coil 1 </ b> V forms a phase magnetic field V on the magnetic pole surface 74. Similarly, the phase current IU flowing through the phase coil 2 </ b> U forms a phase magnetic field U on the magnetic pole surface 84. The phase current IW flowing through the phase coil 2 W forms a phase magnetic field W on the magnetic pole surface 84. The phase current IV flowing through the phase coil 2V forms a phase magnetic field V on the magnetic pole surface 84.

The pole faces 74 and 84 have angular positions P1-P6. The electrical angle between two angular positions adjacent to each other is 60 degrees. The phase magnetic field -V is synthesized in the first region (P1-P2), the phase magnetic field U is formed in the second region (P2-P3), and the phase magnetic field -W is synthesized in the third region (P3-P4). . The phase magnetic field V is formed in the fourth region (P4-P5), the phase magnetic field -W is combined with the fifth region (P5-P6), and the phase magnetic field W is formed in the sixth region (P6-P1). FIG. 19 is a vector diagram showing six phase magnetic fields -V, U, -W, V, -U, and W. Six phase magnetic field vectors separated from each other by an electrical angle of 60 degrees are formed within an electrical angle of 360 degrees.

The double phase mode will be described with reference to FIGS. FIG. 20 is a side view showing the front stator core 71. FIG. 21 is a side view showing the rear stator core 81. 20 is essentially the same as FIG. 16, and FIG. 21 is essentially the same as FIG. However, the phase of each phase current supplied to each phase coil 1U-2W is changed. -U phase current -IU has opposite phase to U phase current IU, -V phase current -IV has opposite phase to V phase current IV, -W phase current -IW has opposite phase to W phase current IW .

FIG. 22 is a circumferential development view showing the arrangement of the magnetic pole surfaces 74 and 84 in the double phase mode. This arrangement is called a double phase arrangement. Phase current IU is supplied to phase coil 1U, phase current IV is supplied to phase coil 1W, and phase current IW is supplied to phase coil 1V. Further, the phase current -IU is supplied to the phase coil 2U, the -phase current -IW is supplied to the phase coil 2V, and the phase current -IV is supplied to the phase coil 2W. As a result, the three magnetic pole surfaces 74 form the phase magnetic fields U, V, and W in order, and the three magnetic pole surfaces 84 form the phase magnetic fields -U, -V, and -W in order.

The pole faces 74 and 84 have angular positions P1-P12. The electrical angle between two adjacent ones of the angular positions P1 to P12 is 30 degrees. A phase magnetic field (U-V) is synthesized in the first region (P1-P2). A phase magnetic field U is formed in the second region (P2-P3). The phase magnetic field (U-W) is synthesized in the third region (P3-P4). A phase magnetic field -W is formed in the fourth region (P4-P5). The phase magnetic field (V-W) is synthesized in the fifth region (P5-P6). A phase magnetic field V is formed in the sixth region (P6-P7). Similarly, the phase magnetic field (V-U) is synthesized in the seventh region (P7-P8). The phase magnetic field -U is formed in the eighth region (P8-P9). The phase magnetic field (W-U) is synthesized in the ninth region (P9-P10). A phase magnetic field W is formed in the tenth region (P10-P11). The phase magnetic field (W-V) is synthesized in the eleventh region (P11-P12). The phase magnetic field -V is formed in the twelfth region (P12-P1). Eventually, according to this double phase mode, twelve phase magnetic field vectors are formed within an electrical angle of 360 degrees. FIG. 23 is a vector diagram showing these phase magnetic field vectors.

The double pole stator shown in FIG. 18 is compared with the conventional distributed winding stator shown in FIG. Each of the double pole stator and the distributed winding stator has six phase magnetic field vectors per 360 electrical degrees. However, the double pole stator has a shorter coil end than the distributed winding stator. Therefore, the double pole stator can have a lower resistance ratio than the conventional distributed winding stator.

The double phase stator shown in FIG. 22 is compared with the conventional distributed winding stator shown in FIG. Each of the double phase stator and the distributed winding stator has 12 phase magnetic field vectors per 360 electrical degrees. However, double phase stators have much shorter coil ends than distributed winding stators. Therefore, the double phase stator can have a lower resistance ratio than the distributed winding stator. Eventually, the tandem induction motor of this embodiment can realize suppression of harmonic magnetic field and reduction of copper loss.

The controller 100 executes switching control between the double pole mode and the double phase mode. This switching technique, called the pole number switching technique, is executed by adjusting the phase of each phase current supplied to the six phase coils 1U-2W, as can be understood from FIGS. A double pole array is selected in the low speed region and a double phase array is selected in the high speed region. Next, the winding number switching technique will be described with reference to FIGS. This winding number switching technique includes a serial mode and a parallel mode. The number of turns in the serial mode is equivalently doubled compared to that in the parallel mode.

FIG. 24 is a timing chart showing a waveform example of the six phase currents I1-I6 shown in FIG. The phase currents I1 to I6, which are symmetrical six-phase currents, each have a substantially sinusoidal waveform. Phase current I1 and phase current 14 have opposite phases. Phase current I2 and phase current 15 have opposite phases. The phase current I3 and the phase current 16 have opposite phases.

The parallel mode is essentially the same as the operation mode of a conventional symmetrical 6-phase motor. In this parallel mode, the three-phase inverter 3 outputs three phase voltages V 1 -V 3 to the three-phase coil 1, and the three-phase inverter 4 outputs three phase voltages V 4 -V 6 to the three-phase coil 2. The two three- phase inverters 3 and 4 are controlled independently. Three- phase coils 1 and 2 are connected in parallel to a DC power supply (not shown) through three- phase inverters 3 and 4.

The serial mode is described. According to this series mode, each one leg of the three- phase inverters 3 and 4 is fixed to the intermediate voltage VM. Preferably, this intermediate voltage is approximately equal to half the value of the DC power supply voltage Vd (0.5 Vd). Hereinafter, the leg that outputs the intermediate voltage VM is referred to as an intermediate potential leg. The PWM duty ratio of the intermediate potential leg is almost 50%. Preferably, the upper arm transistors of the two intermediate potential legs have the same on period and the lower arm transistors have the same on period. Thereby, the ripple of the current supplied from the DC power source to the three- phase inverters 3 and 4 is reduced. In order to avoid the adverse effect of the intermediate potential fixing on the six-phase currents I1-I6, a predetermined bias voltage is superimposed on the output voltages of the four legs other than the intermediate potential leg. Thereby, the six-phase current is not changed by this intermediate potential fixation.

The fact that each leg of the three- phase inverters 3 and 4 outputs the same intermediate voltage VM means that two phase coils connected to each one of these intermediate potential legs are equivalently connected in series. To do. When the leg 3U becomes an intermediate potential leg, the leg 4U becomes an intermediate potential leg. When the leg 3V becomes the intermediate potential leg, the leg 4V becomes the intermediate potential leg. When the leg 3W becomes the intermediate potential leg, the leg 4W becomes the intermediate potential leg. In other words, two legs that output phase voltages in opposite phases are selected as intermediate potential legs. Therefore, the DC power supply can supply phase currents only to the four legs excluding the two intermediate potential legs. According to this embodiment, the leg supplying the phase current with the maximum amplitude is selected as the intermediate potential leg. As a result, the reduction rate of the current supplied from the DC power source to the three- phase inverters 3 and 4 is maximized. The leg that supplies the phase current with the maximum amplitude is called the maximum current leg. Therefore, this winding number switching method is called a maximum current leg selection method.

This maximum current leg selection method will be described with reference to FIG. In FIG. 24, one cycle period TC (= electrical angle 360 degrees) has six switching time points t1 to t6. The electrical angle between any two of the six points in time t1-t6 is 60 degrees. The phase current I3 becomes zero at time points t1 and t4. The phase current I2 becomes zero at time points t2 and t5. The phase current I1 becomes zero at time points t3 and t6.

In the first phase period (t1-t2) in which the amplitudes of the phase currents I1 and I4 are maximum, the legs 3U and 4U are intermediate potential legs. In the second phase period (t2-t3) in which the amplitudes of the phase currents I3 and I6 are maximum, the legs 3W and 4W are intermediate potential legs. In the third phase period (t3-t4) in which the amplitudes of the phase currents I2 and I5 are maximum, the legs 3V and 4V are intermediate potential legs.

Similarly, in the fourth phase period (t4-t5) in which the amplitudes of the phase currents I1 and I4 are maximum, the legs 3U and 4U are intermediate potential legs. In the fifth phase period (t5-t6) in which the amplitudes of the phase currents I3 and I6 are maximum, the legs 3W and 4W are intermediate potential legs. In the sixth phase period (t6-t1) in which the amplitudes of the phase currents I2 and I5 are maximum, the legs 3V and 4V are intermediate potential legs. Eventually, according to this maximum current leg selection method, the intermediate potential leg is switched between the other two phases when the current command value of one phase becomes zero.

Next, the bias voltage will be described. Phase voltages V1-V6 are regarded as phase voltage command values in the parallel mode. In the first phase period and the fourth phase period in which the legs 3U and 4U are the intermediate potential legs, the bias voltage VB3 (= VM-V1) is added to the phase voltages V2 and V3, respectively. Thereby, the leg 3V outputs the correction phase voltage V2C (= V2 + VM-V1), and the leg 3W outputs the correction phase voltage V3C (= V3 + VM-V1). Similarly, the bias voltage VB4 (= VM−V4) is added to the phase voltages V5 and V6, respectively. Accordingly, the leg 4V outputs the correction phase voltage V5C (= V5 + VM-V4), and the leg 4W outputs the correction phase voltage V6C (= V6 + VM-V4).

In the second phase period and the fifth phase period in which the legs 3W and 4W are the intermediate potential legs, the bias voltage VB3 (= VM−V3) is added to the phase voltages V1 and V2, respectively. Accordingly, the leg 3U outputs the correction phase voltage V1C (= V1 + VM-V3), and the leg 3V outputs the correction phase voltage V2C (= V2 + VM-V3). Similarly, the bias voltage VB6 (= VM−V6) is added to the phase voltages V4 and V5, respectively. Thereby, the leg 4U outputs the correction phase voltage V4C (= V4 + VM−V6), and the leg 4V outputs the correction phase voltage V5C (= V5 + VM−V6).

In the third phase period and the sixth phase period in which the legs 3V and 4V are the intermediate potential legs, the bias voltage VB2 (= VM−V2) is added to the phase voltages V1 and V3, respectively. Thereby, the leg 3U outputs the correction phase voltage V1C (= V1 + VM-V2), and the leg 3W outputs the correction phase voltage V3C (= V3 + VM-V2). Similarly, the bias voltage VB5 (= VM−V5) is added to the phase voltages V4 and V6, respectively. Accordingly, the leg 4U outputs the correction phase voltage V4C (= V4 + VM−V5), and the leg 4W outputs the correction phase voltage V6C (= V6 + VM−V5).

In FIG. 25, the vectors of the correction phase voltages V1C, V3C, V4C, and V6C in the third phase period and the sixth phase period are indicated by broken lines. In FIG. 26, vectors of the correction voltages V2C, V3C, V5C, and V6C in the first phase period and the fourth phase period are indicated by broken lines. In FIG. 27, vectors of the correction voltages V1C, V2C, V4C, and V5C in the second phase period and the fifth phase period are indicated by broken lines.

The controller 100 executes either or both of the above-described pole number switching and winding number switching based on the speed and torque command value. The series mode and the double pole mode are preferably selected in the low speed and high torque region. The parallel mode and the double phase mode are preferably selected in the high speed region. According to this series mode, the power source current supplied from the DC power source to the three- phase inverters 3 and 4 is halved compared to the conventional parallel mode. This means that the three- phase coils 1 and 2 are equivalently connected in series.

The bipolar mode can be performed simultaneously with the serial mode. In the series mode, the three- phase inverters 3 and 4 need to output three-phase currents having opposite phases to each other in the series mode. However, in the double pole mode, for example, the phase coils 1U and 2U need to form an in-phase magnetic field. This problem is solved by making the winding directions of the phase coils 2U, 2V, and 2W opposite to those of the phase coils 1U, 1V, and 1W.

One variation is described. In the case where the pole number switching technique and the winding number switching technique are not adopted, the three- phase coils 1 and 2 connected in series or in parallel can be connected to one three-phase inverter. This drive circuit having one three-phase inverter is called a single inverter circuit. Another variation is described. In constant speed applications where the pole number switching technique and the winding number switching technique are not employed, the three- phase coils 1 and 2 connected in series or in parallel can be directly connected to a commercial three-phase AC power source.

Another variation is described. The three- phase inverters 3 and 4 can execute a new four-phase mode. In this four-phase mode, the three- phase inverters 3 and 4 are each driven by a known two-phase modulation method. In this four-phase mode that is preferably used in a double phase arrangement, the three-phase voltage output by the three-phase inverter 3 has the opposite phase to the three-phase voltage output by the three-phase inverter 4. When one leg of the three-phase inverter 3 is fixed at the highest potential, one leg of the three-phase inverter 4 having the opposite phase to this leg is fixed at the lowest potential. Accordingly, the two leakage currents formed by the harmonic voltages output from the three- phase inverters 3 and 4 are canceled out from each other. Preferably, the switching between the four-phase mode and the series mode is smoothly performed by gradually changing the bias voltage VB. This four-phase mode reduces inverter loss.

Another variation is described. The tandem motor can flow the cooling fluid in the radial direction through the gap 400 shown in FIG. The cylindrical portion of the housing 5 can have a hole communicating with the gap 400. Thereby, the cooling of the three- phase coils 1 and 2 is improved.

Second Embodiment A tandem synchronous motor according to a second embodiment will be described with reference to FIGS. FIG. 28 is an axial sectional view showing the tandem motor. Each of the front motor 7 and the rear motor 8 is a permanent magnet synchronous motor (PMSM). The rotor cores 73 and 83 each have a permanent magnet.

FIG. 29 is a wiring diagram showing a single inverter drive type drive circuit for driving the tandem synchronous motor. The three-phase inverter 3 is connected to three- phase coils 1 and 2 connected in series for each phase. The three-phase inverter 3 can also be connected to the three- phase coils 1 and 2 connected in parallel to each other. The phase leg 3U supplies a U-phase current IU to the phase coils 1U and 2U. The phase leg 3V supplies the V-phase current IV to the phase coils 1V and 2V. Phase leg 3V supplies W phase current IW to phase coils 1W and 2W.

FIG. 30 is a schematic development view showing a double pole arrangement. This double pole arrangement is essentially the same as the tandem stator shown in FIG. Each of the rotor cores 73 and 83 has four rotor poles per three adjacent phase coils. In other words, each of the front motor 7 and the rear motor 8 is a three-slot four-pole type concentrated winding synchronous motor. Therefore, the electrical angle of 360 degrees corresponds to 1.5 times the phase slot pitch.

The phase coil 1 U forms a phase magnetic field U on the magnetic pole surface 74, the phase coil 1 V forms a phase magnetic field V on the magnetic pole surface 74, and the phase coil 1 W forms a phase magnetic field W on the magnetic pole surface 74. Similarly, the phase coil 2 U forms a phase magnetic field U on the magnetic pole surface 84, the phase coil 2 V forms a phase magnetic field V on the magnetic pole surface 84, and the phase coil 2 W forms a phase magnetic field W on the magnetic pole surface 84.

This tandem motor can be driven by a square wave instead of a sine wave. In other words, the tandem motor can be driven as a brushless DC motor. Since the circumferential lengths of the magnetic pole surfaces 74 and 84 substantially coincide with the circumferential length of the rotor magnetic poles, it is preferable that this brushless DC motor adopts the 180 degree energization method rather than the 120 degree energization method.

FIG. 31 is a development view showing the double phase arrangement. This double phase arrangement is essentially the same as the tandem stator shown in FIG. Similar to FIG. 30, the rotor cores 73 and 83 each have four rotor poles per three phase coils. The three-phase current supplied to the front coil 1 consisting of the phase coils 1U, 1V and 1W is 180 degrees in electrical angle compared to the three-phase current supplied to the rear coil 2 consisting of the phase coils 2U, 2V and 2W. Has a different phase. The phase coil 1 U forms a phase magnetic field U on the magnetic pole surface 74, the phase coil 1 V forms a phase magnetic field V on the magnetic pole surface 74, and the phase coil 1 W forms a phase magnetic field W on the magnetic pole surface 74. The phase coil 2U forms a phase magnetic field -U on the magnetic pole surface 84, the phase coil 2V forms a phase magnetic field -V on the magnetic pole surface 84, and the phase coil 2W forms a phase magnetic field -W on the magnetic pole surface 84.

One cycle of the six-phase current shown in FIG. 31 is twice the one cycle of the three-phase current shown in FIG. Therefore, the number of stator poles in FIG. 31 is half the number of stator poles in FIG. Six phase magnetic fields U, V, W, -U, -V, and -W are formed within a circumferential distance equal to three times the circumferential width of the phase coil. In other words, the double phase array shown in FIG. 31 has a double phase magnetic field vector in the range of an electrical angle of 360 degrees corresponding to one cycle of the phase current, compared to the double pole array shown in FIG. Therefore, the double phase arrangement realizes concentrated winding with low torque ripple.

In one modification, a double inverter drive circuit is employed in which the three-phase inverter 3 drives the three-phase coil 1 and the three-phase inverter 4 drives the three-phase coil 2. Thereby, the number-of-turns switching technique and the four-phase mode technique shown in FIG. 24 can be executed.

In another variation, the front rotor core 73 generates mainly magnet torque, and the rear rotor core 83 generates mainly synchronous reluctance torque. The front motor 7 is a permanent magnet motor (PMSM), and the rear motor 8 is a synchronous reluctance motor (SynRM). The rotor core 73 has a plurality of permanent magnets, and the rotor core 83 has a plurality of flux barriers. The front rotor core 73 can generate both permanent magnet torque and synchronous reluctance torque.

One drawback of permanent magnet synchronous motors is an increase in counter electromotive force in the high speed region. In order to improve this problem, the three-phase inverter 4 adjusts the reluctance torque of the rear motor 8. It is preferable that the relative angle between the front rotor core 73 and the rear rotor core 83 is set to a value at which both the motors 7 and 8 simultaneously generate the maximum torque.

Third Embodiment A tandem starter generator according to a third embodiment will be described with reference to FIGS. This starter generator has an engine start mode and a power generation mode. FIG. 32 is an axial sectional view showing this starter generator. The three-phase coil 1 is concentrated around the stator core 71, and the three-phase coil 2 is concentrated around the stator core 81. The front motor 7 has a Landel type rotor core 73 around which a field coil 730 is wound. The rear motor 8 has a Landel type rotor core 83 around which a field coil 830 is wound. Each of the Landel rotor cores 73 and 83 is essentially the same as a conventional Landel rotor core.

The rotor core 73 includes a core 731 and a core 732. Each of the cores 731 and 732 has an L-shaped rotor pole 733 extending from the boss portion. The rotor core 83 includes a core 831 and a core 832. Each of the cores 831 and 832 has an L-shaped rotor pole 833 extending from the boss portion. The cores 732 and 831 can be made integrally. The field coil 730 magnetizes the rotor pole 733, and the field coil 830 magnetizes the rotor pole 833.

FIG. 33 is a development view showing the arrangement of the rotor poles 733 and 833. The rotor pole 733 of the core 731 and the rotor pole 833 of the core 832 are arranged at odd-numbered positions in the circumferential direction. The rotor pole 733 of the core 732 and the rotor pole 833 of the core 831 are arranged at even-numbered positions in the circumferential direction. The rotor pole 733 of the core 731 has an N pole, and the rotor pole 733 of the core 732 has an S pole. The rotor pole 833 of the core 831 has an S pole in the engine start mode and an N pole in the power generation mode. The rotor pole 833 of the core 832 has an N pole in the engine start mode and an S pole in the power generation mode.

FIG. 34 is a wiring diagram showing a rotor circuit for supplying a field current to the field coils 730 and 830. This rotor circuit includes a single-phase full bridge (H bridge) 11 and a diode circuit 13. The H bridge 11 fixed to the housing 5 includes two switch legs 111 and 112. The diode circuit 13 includes a diode pair 130 for voltage drop, two parallel diodes 131 and 132, and a series diode 133. The diode pair 130 composed of two diodes connected in reverse parallel can be omitted.

One end of the field coil 830 is connected to the output terminal of the switch leg 111 through the diode pair 130 and the slip ring 17. The slip ring 17 is connected to the anode electrode of the parallel diode 131. The other end of the field coil 830 is connected to the anode electrode of the parallel diode 132 and one end of the field coil 730. The other end of the field coil 730 is connected to the cathode electrode of the parallel diode 131 and the cathode electrode of the series diode 133. The anode electrode of the series diode 133 and the cathode electrode of the parallel diode 132 are connected to the output terminal of the switch leg 112 through the slip ring 18.

FIG. 35 is a side view showing the terminal ring 19 incorporating the diode circuit 13. This terminal ring 19 fixed to the rotary shaft 12 has two terminals 134 to which one ends of the field coils 730 and 830 are separately connected. Further, the terminal ring 19 has two terminals (not shown) that are separately connected to the slip rings 17 and 18. The H bridge 11 is fixed to the housing 5.

In the engine start mode, the field current flows from the switch leg 111 to the switch leg 112. Thereby, the field coils 830 and 730 are connected in parallel. For this reason, the field current can rise rapidly in the early stage of engine start. The field current flows from the switch leg 112 to the switch leg 111 in the power generation mode. Thereby, the two field coils 830 and 730 are connected in series. In the engine start mode and the power generation mode, the direction of the field current flowing through the field coil 730 is unchanged, and the direction of the field current flowing through the field coil 830 is opposite. Therefore, when mode switching between the engine start mode and the power generation mode is commanded, the polarity of the rotor pole 833 is reversed.

36 and 37 are developed views showing the arrangement of the three- phase coils 1 and 2. FIG. The three-phase coil 1 includes phase coils 1U, 1V, and 1W separated from each other by an electrical angle of 120 degrees. The three-phase coil 2 includes phase coils 2U, 2V, and 2W that are 120 degrees apart from each other. The phase coils 1U-1W are wound around the stator pole 74 in order. The phase coils 2U-2W are wound around the stator pole 84 in order. Phase coils 1U and 2U have the same circumferential position, phase coils 1V and 2V have the same circumferential position, and phase coils 1W and 2W have the same circumferential position. Phase coil 1U generates back electromotive force VU1, phase coil 1V generates back electromotive force VV1, and phase coil 1W generates back electromotive force VW1. Similarly, phase coil 2U generates counter electromotive force VU2, phase coil 2V generates counter electromotive force VV2, and phase coil 2W generates counter electromotive force VW2.

Each back electromotive force in the engine start mode will be described with reference to FIG. The rotor poles 733 and 833 of the cores 731 and 832 have an N pole, and the rotor poles 733 and 833 of the cores 732 and 831 have an S pole. Thereby, the counter electromotive forces VU1 and VU2 are in phase with each other, the counter electromotive forces VV1 and VV2 are in phase with each other, and the counter electromotive forces VW1 and VW2 are in phase with each other. Eventually, this engine start mode in which the three- phase coils 1 and 2 generate a three-phase counter electromotive force in phase with each other generates the same three-phase counter electromotive force as that of a conventional three-phase concentrated winding motor.

The counter electromotive force in the power generation mode will be described with reference to FIG. In this power generation mode, these back electromotive forces mean the generated voltage of each phase. The rotor poles 733 and 833 of the cores 731 and 831 have an N pole, and the rotor poles 733 and 833 of the cores 732 and 832 have an S pole. Thus, the counter electromotive forces VU1 and VU2 are in opposite phases, the counter electromotive forces VV1 and VV2 are in opposite phases, and VW1 and VW2 are in opposite phases. Therefore, according to this power generation mode, six back electromotive force vectors are formed within an electrical angle of 360 degrees. In other words, in this power generation mode, the tandem stator has a double phase arrangement.

FIG. 38 is a wiring diagram showing a power converter connected to the three- phase coils 1 and 2. This power converter includes a three-phase full-bridge rectifier 3 and a three-phase inverter 4. The three-phase coil 1 is a star-shaped (Wye) coil having a neutral point N. The three-phase coil 2 is an independent three-phase coil. Phase coil 2U is connected in series with phase coil 1U, phase coil 2V is connected in series with phase coil 1V, and phase coil 2W is connected in series with phase coil 1W. The rectifier 3 consists of legs 3U, 3V, and 3W. The leg 3U is connected to the connection point of the phase coils 1U and 2U, the leg 3V is connected to the connection point of the phase coils 1V and 2V, and the leg 3W is connected to the connection point of the phase coils 1W and 2W. The three-phase inverter 4 includes legs 4U, 4V, and 4W. The leg 4U is connected to the phase coil 2U, the leg 4V is connected to the phase coil 2V, and the leg 4W is connected to the phase coil 2W.

In the power generation mode, the rectifier 3 performs full-wave rectification on the three-phase voltage output from the star-connected three-phase coil 1. The rectifier 3 full-wave rectifies the highest terminal voltage among the three terminal voltages Ve, Vf, and Vg. The terminal voltage Ve is the higher of the interphase voltage VU1-VV1 and the interphase voltage VU1-VW1. The terminal voltage Vf is the higher of the interphase voltage VV1-VU1 and the interphase voltage VV1-VW1. The terminal voltage Vg is the higher of the interphase voltage VW1-VU1 and the interphase voltage VW1-VV1. Further, in this power generation mode, the rectifier 3 and the three-phase inverter 4 constitute three single-phase full-bridge rectifiers that rectify the generated voltage of the three-phase coil 2. Legs 3U and 4U full-wave rectify phase voltage VU2, legs 3V and 4V full-wave rectify phase voltage VV2, and legs 3W and 4W full-wave rectify phase voltage VW2.

In order to reduce the current imbalance of the two three- phase coils 1 and 2, the phase coils 2U, 2V and 2W of the three-phase coil 2 are increased over the phase coils 1U, 1V and 1W of the three-phase coil 1. Has the number of turns. Preferably, a value close to about 1.73 times the winding value of the three-phase coil 1 is selected as the winding value of the three-phase coil 2. For example, the three-phase coil 2 has 5/3 times the number of turns of the three-phase coil 1. Thereby, the three phase voltages of the three-phase coil 2 have substantially the same amplitude as the three terminal voltages Ve, Vf and Vg of the three-phase coil 1.

FIG. 39 is a vector diagram showing the generated voltage applied to the three-phase rectifier 3 and the three-phase inverter 4. The three-phase rectifier 3 and the three-phase inverter 4 substantially full-wave rectify the six-phase voltage. The ripple of generated current is greatly reduced.

In the engine start mode, the three-phase inverter 4 supplies a three-phase current to the three- phase coils 1 and 2. The three-phase inverter 4 preferably outputs a three-phase rectangular wave voltage. In other words, the tandem starter generator operates as a so-called brushless DC motor. The three- phase coils 1 and 2 substantially constitute one synthetic star coil. The U-phase coil of this synthetic star coil is composed of phase coils 1U and 2U connected in series. The counter electromotive forces of the phase coils 1U and 2U are in the same direction in the engine start mode. The V-phase coil of this synthetic star coil consists of phase coils 1V and 2V connected in series. The counter electromotive forces of the phase coils 1V and 2V are in the same direction in the engine start mode. The W-phase coil of this synthetic star coil is composed of phase coils 1W and 2W connected in series. The counter electromotive forces of the phase coils 1W and 2W are in the same direction in the engine start mode.

When the three-phase coil 2 has about 1.73 times the number of turns of the three-phase coil 1, the composite star coil has about 2.73 times the number of turns compared to the three-phase coil 1. Therefore, this starter generator can generate a powerful engine starting torque. FIG. 40 is a vector diagram showing three combined counter electromotive forces Va, Vb, and Vc applied to the legs 4U-4W in the engine start mode. When the neutral point N has the neutral point potential Vn, the combined counter electromotive force Va becomes the vector sum of the counter electromotive forces VU1 and VU2, and the combined counter electromotive force Vb becomes the vector sum of the counter electromotive forces VV1 and VV2, and the combined inverse The electromotive force Vc is a vector sum of the counter electromotive forces VW1 and VW2. Instead of the three-phase inverter 4, a three-phase diode rectifier may be employed. This motor is a two-voltage type alternator. A three-phase inverter may be employed instead of the three-phase rectifier 3.

Fourth Embodiment Copper loss is reduced by improving the slot space factor. The so-called divided core is effective in improving the slot space factor. However, the split core increases motor vibration. In particular, when a tandem motor in which two stator cores vibrate separately adopt this split core, the relative vibration between the stator cores increases. This problem is solved by the stator core manufacturing method described in this embodiment. This manufacturing method includes an alignment process and a die casting process.

FIG. 41 is a schematic diagram showing an alignment process for aligning the six core segments 70. Each core segment 70 made of laminated steel sheets has an arcuate yoke 75 extending from the stator pole 72 to both sides in the circumferential direction. The end surface 76 of the arcuate yoke 75 extends in the radial direction. The phase coils 1U-1W are separately concentrated and wound around the six stator poles 72. Each core segment 70 is arranged around a cylindrical mold 60. Each core segment 70 urged toward the radially inner side F is brought into close contact with the outer peripheral surface of the mold 60. As a result, the six core segments 70 form the front stator core 71.

FIG. 42 is a radial cross-sectional view showing the die casting process. The die casting molds 61 and 62 have a cylindrical cavity 50. A stator assembly comprising aligned core segments 70 is disposed in the cavity 50 along with the cylindrical mold 60. Thereafter, molten aluminum is injected into the cavity 50. The cooled aluminum forms the cylindrical part of the housing 5. Thereafter, the molds 60, 61, and 62 are removed. Thereby, each core segment 70 is firmly fixed to the cylindrical portion of the housing 5.

FIG. 43 is a sectional view in the axial direction of a die casting mold. Annular molds 63 and 64 are arranged on both sides of the cavity 50 in the axial direction. The mold 63 is in close contact with the front end face of each core segment 70, and the mold 64 is in close contact with the rear end face of each core segment 70. Thereby, the cavity 50 is completely sealed. The molds 63 and 64 have holes through which the mold 60 passes. After the cylindrical portion of the housing 5 is formed, the mold 63 slides forward and the mold 64 slides backward.

A first modification will be described with reference to FIGS. 44 and 45. FIG. 44 is a radial sectional view showing a part of the front motor 7. FIG. 46 is an axial sectional view of the front motor 7. Each core segment 70 has five wedge portions 77 projecting radially outward from the arcuate yoke 75. Thereby, each core segment 70 is firmly fixed to the housing 5. After the rotor core 73 is inserted into the stator, both end wall portions of the housing 5 are fastened to the cylindrical portion of the housing 5.

The cylindrical portion of the housing 5 has a large number of annular flanges 51. Each annular flange 51 is provided on the outer peripheral surface of the cylindrical portion of the housing 5. A resin water jacket 52 is placed on the cylindrical portion of the housing 5. Thereby, the annular water cooling passage 53 is formed between the two annular flanges 51 adjacent in the axial direction. It is also possible to supply oil to the water cooling passage 53 instead of the cooling water. The water jacket 52 has a water supply pipe and a drain pipe for flowing water through each water cooling passage 53. Thereby, the stator 71 is cooled well through the housing 5. The annular flange 51 reduces the thermal resistance between the cooling water flowing through each water cooling passage 53 and the housing 5. Each annular flange 51 improves the rigidity of the housing 5.

A second variation will be described. According to this modification, the rear stator core 81 is formed of six core segments in the same manner as the front stator core 71. The aligned core segments for the stator cores 71 and 81 together with the spacers 15 constitute a stator assembly. After the stator assembly is accommodated in the mold, the cylindrical portion of the housing 5 is manufactured by a die casting method. Thereby, the stator core 71, the spacer 15, and the stator core 81 are fixed to the housing 5. At least the outer peripheral portion of the spacer 15 is made of a nonmagnetic metal having a melting point higher than that of the housing 5. For example, the spacer 15 includes a copper outer sleeve and an aluminum inner sleeve. The outer peripheral surface of the outer sleeve can have a recess or a protrusion.

A third variation will be described with reference to FIG. The even-numbered core segment 70 out of the six core segments 70 is in contact with the outer peripheral surface of the cylindrical mold 60 in advance. Thereafter, only the odd-numbered core segment 70 is moved radially inward. Thereby, the mold moving device becomes compact.

A fourth modification will be described with reference to FIG. The cylindrical mold 60 has a tapered shape. In other words, the diameter of the long cylindrical mold 60 continuously increases in the axial direction. In the initial stage of the alignment process, each core segment 70 is urged toward the outer peripheral surface of the large-diameter portion of the mold 60. Further, the mold 60 is moved in the axial direction. As a result, each core segment 70 is in close contact with the outer peripheral surface of the small diameter portion of the mold 60. Thereby, each core segment 70 can move smoothly in the radially inward direction. After all, according to the manufacturing method of this embodiment, the relative vibration of the stator cores 71 and 81 and the relative vibration between the segments are suppressed.

A fifth modification will be described with reference to FIG. In this variation, each core segment 70 of the split core has a T-shape. In other words, the core segment 70 has a yoke portion 75 extending in the tangential direction from the stator pole 72 extending in the radially inward direction. The yoke portions 75 connected in a ring form a so-called back core. The end surface 76 of the yoke portion 75 extends in the radial direction. The flange 79 extends the magnetic pole surface 74 in the circumferential direction. The front stator core 71 formed by the six core segments 70 has a hexagonal cylindrical shape. A yoke portion 75 extending perpendicularly from the stator pole 72 enlarges the cross-sectional area of the slot 78 and facilitates the automatic winding operation of the phase coil 1U.

The copper loss reduction effect of the tandem concentrated winding motor described in the above embodiments will be described with reference to FIGS. 46 and 47. FIG. FIG. 47 shows one core segment 70 as a comparative example. The core segment in FIG. 46 occupies 60 degrees, and the core segment in FIG. 47 occupies 30 degrees. In other words, FIG. 47 shows a core segment of a fifth modification that forms a conventional concentrated winding stator core. 46, when the stator pole half of the conventional concentrated winding stator core occupies 30 degrees, the core segment 70 in FIG. 46 occupies 60 degrees in the core segment 70 in FIG. In the following, the stator pole 72 of the core segment 70 in FIG. 46 is called a tandem pole, and the stator pole 72 of the core segment 70 in FIG. 47 is called a comparison pole.

Both have equal pole face diameter R and equal outer diameter H. The tandem pole has a circumferential width that is twice the circumferential width W of the comparison pole. The tandem pole has an axial length that is six times the width W of the comparison pole. The axial length of the comparison pole has an axial length 12 times the width W of the comparison pole. Therefore, the tandem pole and the comparison pole have the same magnetic pole area.

The tandem pole has an average turn length of about 70% compared to the comparison pole. Furthermore, the comparative pole has a slot cross-sectional area of about 60% compared to the tandem pole. Eventually, a double pole array stator coil has a copper loss of less than 45% compared to a conventional concentrated winding stator coil.

However, the tandem concentrated winding motor has an increased weight over the concentrated winding motor with the comparison pole. This increase in weight results from an increase in the axial length of the housing and the rotating shaft, the width of the yoke portion, and the cross-sectional area of the stator coil. However, both the permanent magnets, the rotor core and the stator pole have the same weight. Furthermore, since two tandem poles adjacent in the axial direction overlap in the circumferential direction, the tandem concentrated winding motor has an effect of improving the magnet utilization rate and a torque ripple as compared with the conventional concentrated winding motor.

A fifth embodiment tandem distributed winding motor will be described with reference to FIGS. The tandem distributed winding motor shown in FIG. 48 is essentially the same except for the tandem motor and the stator coil shown in FIG. The front rotor core 73 and the rear rotor core 83 have any of the rotor structures of the first to third embodiments. FIG. 48 shows the rotor structure of the second embodiment.

49 is a development view of the stator core 71 of the front motor 7, and FIG. 50 is a development view of the stator core 81 of the rear motor 8. The stator core 71 has six slots S1-S6 within an electric angle range of 360 degrees. The stator core 81 has six slots S7 to S12 within an electric angle of 360 degrees. In other words, each of the front motor 7 and the rear motor 8 has three teeth 10 per rotor pole.

The three-phase coil 1 includes phase coils 1U, 1V, and 1W connected in a star shape. The three-phase coil 2 includes phase coils 2U, 2V, and 2W connected in a star shape. Phase current IU and -U phase current -IU flow through phase coils 1U and 2U. The phase current -IU means a phase current IU that flows in the reverse direction. Phase currents IV and -IV flow through phase coils 1V and 2V. The phase current -IV means the phase current IV flowing in the reverse direction. Phase currents IW and -IW flow through phase coils 1W and 2W. The phase current -IW means the phase current IW that flows in the reverse direction. U-phase coils 1U and 2U can be connected in parallel or in series. The phase coils 1V and 2V can be connected in parallel or in series. The phase coils 1W and 2W can be connected in parallel or in series.

Slots S1 and S4 accommodate phase coils 1U and 2U. Slots S2 and S5 accommodate phase coils 1W and 2W. Slots S3 and S6 accommodate phase coils 1V and 2V. Slots S1-S6 are called in-phase slots. Slots S7 and S10 house phase coils 2W and 2U. Slots S8 and S11 accommodate phase coils 1V and 1W. Slots S9 and S12 accommodate phase coils 2U and 2V. Slots S7-S12 are called out-of-phase slots.

FIG. 51 is a vector diagram showing twelve slot currents flowing separately through slots S1-S12. This slot current means a vector sum of all phase currents flowing through one slot. The slots S7 to S12 are separated from the slots S1 to S6 by an electrical angle of 30 degrees in the circumferential direction. The slot current flowing through the slots S1 to S6 is equal to the odd-numbered slot current shown in FIG. The slot current flowing through the slots S7 to S12 is equal to the even-numbered slot current shown in FIG. In other words, the tandem distributed winding shown in FIG. 48 can form a rotating magnetic field equal to the conventional distributed winding shown in FIG.

According to this embodiment, the stator core 81 has an axial length 2 / 1.73 times that of the stator core 71. Therefore, the slot current flowing through the slots S7 to S12 forms a magnetic field 2 / 1.73 times as large as the slot current flowing through the slots S1 to S6. The twelve slot currents shown in FIG. 53 form twelve phase magnetic field vectors having the same amplitude. This distributed winding tandem motor with very low torque ripple is suitable for machine tool motors and submarine motors.

FIG. 52 shows an arrangement of six phase coils 1U-2W. The six phase coils 1U-2W are distributedly wound around the stator core 71 at a full pitch and distributedly wound around the stator core 81 at a short pitch. Further, each of the six phase coils 1U-2W is bent by a half slot pitch in the circumferential direction in an idle space between the stator core 71 and the stator core 81. Thereby, the coil ends of the three- phase coils 1 and 2 shown in FIG. 52 are more compact than the coil ends of the distributed winding coils shown in FIG. Thereby, copper loss and manufacturing cost are reduced.

FIG. 53 shows another arrangement of six phase coils 1U-2W. The six phase coils 1U-2W accommodated in the upper portions of the slots S1-S12 are bent by a one-slot pitch in the circumferential direction in the idle space between the two stator cores 71 and 81. However, the six phase coils 1U-2W housed under the slots S1-S12 are not bent in this idle space. The north pole of the front rotor core 73 is shifted by a half slot pitch in the circumferential direction as compared with the north pole of the rear rotor core 83. Accordingly, FIG. 53 is electromagnetically equivalent to FIG.

The tandem distributed winding shown in FIG. 53 can be manufactured by a so-called segment conductor insertion method. The winding process by this segment conductor insertion method will be described. First, an I-shaped conductor indicated by a solid line is inserted above the slots S1-S12. Next, only the stator core 81 is rotated by one slot pitch. As a result, the I-shaped conductor indicated by the solid line is bent by one slot pitch in the circumferential direction in the idle space. At this time, it is preferable to reduce the distance between the stator cores 71 and 81 as the stator core 81 rotates. Thereby, damage to the insulating film of the I-shaped conductor due to slip is reduced. Next, the remaining I-shaped conductors indicated by broken lines are inserted below the slots S1-S12. Next, the coil end portions of all the I-shaped conductors are bent in the circumferential direction. Next, the end of the upper I-shaped conductor and the end of the lower I-shaped conductor that are adjacent to each other in the radial direction are welded at a welding point WP. Thereby, a stator coil is completed.

The tandem distributed winding shown in FIG. 52 is compared with the conventional distributed winding shown in FIG. FIG. 54 shows a part of the tandem distributed winding stator shown in FIG. FIG. 55 shows a part of the conventional distributed winding stator shown in FIG. A conventional distributed winding stator has 48 stator poles (teeth) 10, and each stator pole 10 has a circumferential width W and an axial length 2L. Each of the front stator core 71 and the rear rotor core 81 in tandem distributed winding has 24 stator poles (teeth) 10, and each stator pole 10 has a circumferential width 2 W and an axial length L.

Therefore, both stator poles have the same magnetic path cross-sectional area. The slot width is equal to the width of the adjacent stator pole 10. Therefore, each slot S1-S12 in FIG. 54 has a circumferential width 2W and an axial length L. Each slot S1-S12 in FIG. 55 has a circumferential width W and an axial length 23L. It is assumed that the radial heights of the slots S1 to S12 in FIGS. 54 and 55 are equal. As a result, FIGS. 54 and 55 each have 12 slots S1-S12 in the range of 360 electrical degrees.

The resistance loss generated in each slot in FIG. 54 is 1/4 of the resistance loss generated in each slot in FIG. However, since the inductance of the stator coil in FIG. 54 is about half of the inductance of the stator coil in FIG. 55, each phase coil in FIG. 54 has about twice as many turns as each phase coil in FIG. Have. As a result, the slot conductor portions of these two stator coils have approximately equal resistance losses. However, as shown in FIG. 52, the tandem distributed winding is wound around the front stator core 71 at a full pitch and wound around the rear stator core 81 at a short pitch. As a result, a portion of the stator coil 1 wound around the front stator core 71 may have an inductance different from that of the portion wound around the rear stator core 81. This difference in inductance can be eliminated by adjusting the axial length of the rear stator core 81.

The tandem distributed winding stator coil of this embodiment has two in-phase coils accommodated in two layers in the same slot as shown in FIG. This means that the stator coil can be constituted by two three-phase coils. Therefore, by driving these two three-phase coils by separate three-phase inverters, it means that the above-described winding number switching technique and four-phase mode technique can be adopted.

In the tandem distributed winding motor of this embodiment, the axial width of the idle space between the front stator core 71 and the rear stator core 81 is short. For example, this width is shorter than one slot pitch of the front motor 7. Therefore, it is possible to form the front rotor core 73 and the rear rotor core 83 with one rotor core. This common rotor core can have permanent magnets or flux barriers or saddle coils. This tandem distributed winding induction motor can be driven by a commercial power source in the same manner as the tandem concentrated winding induction motor of the first embodiment. Further, the magnetic flux of each stator pole 10 of the front stator core 71 and the rear stator core 81 generates motor torque. According to this embodiment, the stator pole 10 of the front stator core 71 is shifted by a half stator pole pitch in the circumferential direction compared to the stator pole 10 of the rear stator core 81. Further, the stator pole 10 of the front stator core 71 overlaps the stator pole 10 of the rear stator core 81 in the circumferential direction. As a result, the harmonic component of the counter electromotive force generated in the stator coil is reduced.

Sixth Embodiment A tandem synchronous motor according to a sixth embodiment will be described with reference to FIGS. The tandem synchronous motor shown in FIG. 56 has essentially the same structure as the other tandem motors already described. However, in the tandem motor shown in FIG. 56, the front stator core 71 and the rear stator core 81 substantially constitute one common stator core. A common stator coil 1 </ b> C is wound around the front stator core 71 and the rear stator core 81. The axial gap between the front rotor core 73 and the rear rotor core 83 is shortened. In one example, this axial gap to reduce leakage flux between the two rotor cores is 10 millimeters. The front rotor core 73 having a predetermined number of permanent magnets generates magnet torque, and the rear rotor core 83 having a predetermined number of flux barriers generates synchronous reluctance torque. In other words, the front motor 7 is a permanent magnet motor (PMSM), and the rear motor 8 is a synchronous reluctance motor (SynRM).

In this tandem synchronous motor, the relative angle between the d-axis of the front rotor core 73 and the d-axis of the rear rotor core 83 has a predetermined offset value. FIG. 57 is a vector diagram showing the d-axis current and the q-axis current in the case where this offset value is an electrical angle of 45 degrees. The front rotor core 73 generates almost only magnet torque, and the rear rotor core 83 generates only reluctance torque. When the front motor 7 to which the q-axis current Iq1 is supplied generates the maximum torque value, the current Iq1 flowing through the rear motor 8 is decomposed into a d-axis current Id2 and a q-axis current Iq2 having the same amplitude. Thereby, when the front rotor core 73 generates the maximum torque, the rear motor 8 can generate the maximum torque.

FIG. 58 is a vector diagram showing how the front motor 7 generates magnet torque and reluctance torque. The rear rotor core 83 generates only reluctance torque. By causing the stator current I1 composed of the q-axis current Iq1 and the d-axis current Id1 to flow through the front motor 7, the front motor 7 generates a maximum torque value. The stator current I1 flowing through the rear motor 8 is decomposed into a d-axis current Id2 and a q-axis current Iq2 having the same amplitude. Therefore, when the front rotor core 73 generates the maximum torque, the rear motor 8 generates the maximum torque.

Claims (24)

1. A front rotor core and a rear rotor core fixed in tandem to a common rotating shaft, a front stator core having a front salient pole arranged annularly around the front rotor, and a rear salient pole arranged annularly around the rear rotor core A rear stator core having an equal number of front slots between the front salient poles and a rear slot between the rear salient poles, and an annular housing surrounding the front stator core and the rear stator core. In a radial gap type rotating electrical machine comprising:
   The stator coil is composed of two three-phase coils separately and concentratedly wound around the front salient pole and the rear salient pole,
   The two three-phase coils are arranged in at least one of a double pole arrangement in which an electrical angle of 360 degrees corresponds to 1.5 times the stator pole pitch and a double phase arrangement that generates a symmetrical six-phase electromotive force. A radial gap type rotating electrical machine characterized by that.
2. The radial gap type rotating electric machine according to claim 1, wherein the magnetic pole surface of the front salient pole and the magnetic pole surface of the rear salient pole overlap each other in the circumferential direction.
3. The radial gap type rotating electric machine according to claim 1, wherein the rear salient pole is shifted in the circumferential direction by a half of the circumferential pitch of the front salient pole as compared to the front salient pole.
4. 2. The radial gap type rotating electric machine according to claim 1, wherein the front rotor core and the rear rotor core have a common saddle coil including a conductor bar passing through the front rotor core and the rear rotor core in order.
5. The radial gap rotating electric machine according to claim 1, wherein the two three-phase coils are connected to a common three-phase AC power source.
6. The radial gap rotating electric machine according to claim 1, wherein the two three-phase coils are separately connected to two three-phase inverters.
7. The radial gap type rotation according to claim 6, wherein the two three-phase inverters perform switching between the double phase arrangement and the double pole arrangement by changing a phase of a six-phase voltage applied to the two three-phase coils. Electric.
8. The two three-phase inverters fix two phase voltages having opposite phases among the six phase voltages applied to the two three-phase coils to an intermediate voltage, and set the remaining four phase voltages to a predetermined value. The radial gap type rotating electric machine according to claim 6, wherein equivalent winding number switching is executed by adding a bias voltage.
9. The radial gap type rotating electrical machine according to claim 1, further comprising a polarity inversion circuit that inverts the polarity of one of the rear rotor core and the rear rotor core.
10. The radial gap rotating electric machine according to claim 9, wherein the polarity inversion circuit switches only the direction of a field current supplied to one of two field coils separately wound around the front rotor core and the rear rotor core.
11. The polarity inversion circuit includes a diode circuit for fixing a direction of a field current flowing through one of the two field coils, and a single phase for supplying the field current to the two field coils through the diode circuit. The radial gap type rotating electrical machine according to claim 10, comprising a full bridge.
12. The two three-phase coils include a star-connected three-phase coil and an independent three-phase coil having three phase coils separately connected in series to each phase coil of the star-connected three-phase coil. Radial gap type rotating electric machine.
13. The radial gap rotating electric machine according to claim 12, wherein the independent three-phase coil has a larger number of turns than the star-connected three-phase coil.
14. The independent three-phase coil and the star-connected three-phase coil connected in series for each phase are connected to a first three-phase power converter,
    The radial gap type rotating electrical machine according to claim 12, wherein the independent three-phase coil and the star-connected three-phase coil connected in parallel for each phase are connected to a second three-phase power converter.
15. The front salient pole and the rear salient pole each form a core segment together with a divided back core,
    The radial gap rotating electrical machine according to claim 1, wherein each of the core segments has a wedge portion that fits into a fitting portion of the housing.
16. The radial gap type rotating electric machine according to claim 15, wherein the fitting portion of the housing is made of a die-cast member.
17. A front rotor core and a rear rotor core fixed in tandem to a common rotating shaft, a front stator core having a front salient pole arranged annularly around the front rotor, and a rear salient pole arranged annularly around the rear rotor core A rear stator core having an equal number of front slots between the front salient poles and a rear slot between the rear salient poles, and an annular housing surrounding the front stator core and the rear stator core. In a radial gap type rotating electrical machine comprising:
    The stator coil is distributedly wound by insulated conductors alternately wound around a front slot between the front salient poles and a rear slot between the rear salient poles,
    The radial gap type rotating electrical machine, wherein the insulated conductor is bent in a circumferential direction between the front stator core and the rear stator core.
18. The front slot accommodates at least two insulated conductors through which phase currents in phase with each other flow;
    The radial gap rotating electric machine according to claim 17, wherein the rear slot accommodates at least two insulated conductors through which phase currents having different phases flow.
19. The radial gap type rotating electrical machine according to claim 18, wherein the rear salient pole has a longer axial length than the front salient pole.
20. A front rotor core and a rear rotor core fixed in tandem to a common rotating shaft, a front stator core having a front salient pole arranged annularly around the front rotor, and a rear salient pole arranged annularly around the rear rotor core A rear stator core having an equal number of front slots between the front salient poles and a rear slot between the rear salient poles, and an annular housing surrounding the front stator core and the rear stator core. In a radial gap type rotating electrical machine comprising:
    The radial gap rotating electric machine according to claim 1, wherein the front rotor core mainly generates magnet torque, and the rear rotor core mainly generates synchronous reluctance torque.
21. The stator coil is composed of insulated conductors alternately wound around the front slot and the rear slot,
    26. The radial gap rotating electric machine according to claim 25, wherein a relative angle between the front rotor core and the rear rotor core is an angle value at which each of the front rotor core and the rear rotor core can generate a maximum torque.
22. A front rotor core and a rear rotor core fixed in tandem to a common rotating shaft, a front stator core having a front salient pole arranged annularly around the front rotor, and a rear salient pole arranged annularly around the rear rotor core A rear stator core having an equal number of front slots between the front salient poles and a rear slot between the rear salient poles, and an annular housing surrounding the front stator core and the rear stator core. In a radial gap type rotating electrical machine comprising:
    Each of the front stator core and the rear stator core is composed of a T-shaped core segment.
23. 23. The radial gap type rotating electric machine according to claim 22, wherein the core segment has a wedge portion fitted to an inner peripheral surface of the housing.
24. 24. The radial gap type rotating electrical machine according to claim 23, wherein the housing has a die-cast fitting portion that is in close contact with the wedge portion.

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