Rotating electric working machine of the permanent magnet type and vehicle that uses the electric working machine

Abstract

Rotating electric working machine of permanent magnet type, comprising a stator (230) and a rotor (250) which is arranged across a gap (222) corresponding to the stator (230), wherein The rotor (250) comprises: a rotor core (252) having several magnet insertion holes (253) for each magnet pole, each having a substantially rectangular cross-section; and a permanent magnet inserted into each of the magnet insertion holes (253), at both ends in a circumferential direction of each of the multiple magnet insertion holes (253) provided for each magnetic pole of the rotor (250), a non-magnetic section is formed, A bridge section (260) is provided between the adjacent of the several magnet insertion holes (253) to mechanically connect a rotor core section on the outside of the magnet insertion hole (253) with a rotor core section on the inside of the magnet insertion hole (253), circumferential space sections (261) and radial space sections (262) are provided in a first corner, which is a corner between a surface of the magnet insertion hole (253) on the side of the bridge section (260) and a surface of the magnet insertion hole (253) on the outside of the rotor (250), and in a second corner, which is a corner between the surface of the magnet insertion hole (253) on the side of the bridge section (260) and a surface of the magnet insertion hole (253) on the inside of the rotor (250), such that a corner of the long permanent magnet with a rectangular cross-section, which is inserted into the magnet insertion hole (253), does not touch the surfaces of the magnet insertion hole (253) on the side of the bridge section (260), on the outside of the rotor (250) and on the inside of the rotor (250), and wherein the radial space section (262) for the surface of the magnet insertion hole (253) on the side of the bridge section (260) is formed such that its size is reduced at the corner of the permanent magnet, while the circumferential space sections (261) for the surface of the magnet insertion hole (253) on the outside of the rotor (250) and for the surface of the magnet insertion hole (253) on the inside of the rotor (250) are each formed such that their size is reduced at the corner of the permanent magnet, wherein Then, if a minimum width of the rotor core (252) is set on an outer circumferential side of the non-magnetic section W1, a minimum width of the bridge section (260) W2 is set, and a minimum width of a core on the outer circumferential side of the rotor (250) in the first corner of the magnet insertion hole (253) W3 is set, the following relationship is satisfied: W2 < W1 < W3 , and where, if a maximum width of the bridge section (260) W4 is set, the following relationship is satisfied: W2 < W4 < W1 < W3 .

Description

Technical field

[0001] The present invention relates to a permanent magnet type rotating electric machine and a vehicle using the permanent magnet type rotating electric machine. State of the art

[0002] A permanent magnet type rotating electric machine used to drive an electric vehicle such as a hybrid vehicle (HV) and an electric vehicle (EV) is required to achieve high-speed rotation. Specifically, the permanent magnet type rotating electric machine is required to be able to output high power in a high-speed rotation range. For this reason, as the conventional permanent magnet type rotating electric machine comprising an embedded type permanent magnet type rotating electric machine having an auxiliary salient pole capable of field weakening during high-speed rotation and utilizing reluctance torque is used. For example, PTL 1 describes a structure of the permanent magnet type rotating electric machine that can output high power and can mechanically rotate at a high speed.

[0003] A rotor for the permanent magnet type rotating electric machine capable of withstanding such high-speed rotation is provided, comprising a magnet insertion hole for each magnetic pole, the magnet insertion hole having a substantially rectangular cross section, and a long permanent magnet having a rectangular cross section inserted therein. When the permanent magnet is inserted into the magnet insertion hole and the rotating electric machine is driven to cause the rotor to rotate, high stress acts due to centrifugal force, particularly at a corner of the magnet insertion hole that contacts a corner of the permanent magnet. If the stress is high, the stress may cause breakage of the magnet or breakage of the rotor.

[0004] PTL 2 describes a rotor having a magnet recess into which a permanent magnet is inserted and formed at one corner thereof with an outwardly bent bulge so as to prevent a corner of the permanent magnet from contacting the corner of the magnet recess.

[0005] PTL 3 describes a magnetic-type rotating electrical machine provided with: for each magnetic pole, a plurality of magnetic slots into each of which a permanent magnet is inserted; a small-width core part and a large-width core part in a rotor core section between the adjacent magnetic slots in a same magnetic pole of the rotor; and an arc section such that a width of the small-width core section is continuously changed. Citation listPatent literature [PTL 1] JP 2006- 187 189 A [PTL 2] JP H09-294 344 A [PTL 3] JP 2002- 281 700 A [PTL 4] JP 2008- 211 934 A [PTL 5] JP 2006- 311 730 A Summary of the inventionTechnical problem

[0006] In the rotor for the permanent magnet type rotating electric machine described in PTL 1 and PTL 3, a bridge portion (the core portion in the magnet groove) is provided between two adjacent ones of the plurality of magnet insertion holes provided for each magnetic pole. The corner on the bridge portion side of the magnet insertion hole is not designed taking into account the stress in a radial direction and the stress in a circumferential direction of the rotor, as well as the magnetic saturation in the bridge portion. Thus, the above-mentioned permanent magnet type rotating electric machine cannot sufficiently cope with high-speed rotation.Furthermore, PTL 4 and PTL 5 each disclose V-shaped magnet body insertion holes with a bridge section therebetween, wherein at least one permanent magnet is provided in the V-shaped magnet body insertion holes. This achieves a relatively large distance between the permanent magnets and the bridge section. Solution to the problem

[0007] The problem is solved by the features of claims 1, 5, and 6. Particular embodiments are described in the dependent claims. In particular, the permanent magnet type rotating electric machine comprises a stator and a rotor arranged across a gap corresponding to the stator. The rotor includes: a rotor core including a plurality of magnet insertion holes for each magnetic pole, each of which has a substantially rectangular cross section; and a permanent magnet inserted into each of the magnet insertion holes. A non-magnetic portion is formed at both ends in a circumferential direction of each of the plurality of magnet insertion holes provided for each magnetic pole of the rotor.A bridge portion is provided between the adjacent ones of the plurality of magnet insertion holes to mechanically connect a rotor core portion on the outside of the magnet insertion hole to a rotor core portion on the inside of the magnet insertion hole.In a first corner, which is a corner between a surface of the magnet insertion hole on the bridge portion side and a surface of the magnet insertion hole on the outside of the rotor, and in a second corner, which is a corner between a surface of the magnet insertion hole on the bridge portion side and a surface of the magnet insertion hole on the inside of the rotor, space portions are provided which protrude respectively in the circumferential direction and in a radial direction of the rotor in such a manner that a corner of the long permanent magnet having a rectangular cross section inserted into the magnet insertion hole does not contact the surfaces of the magnet insertion hole on the bridge portion side, on the outside of the rotor, and on the inside of the rotor.The gap portion for the surface of the magnet insertion hole on the bridge portion side is formed so that its size is reduced at the corner of the permanent magnet, while the gap portions for the surface of the magnet insertion hole on the outer side of the rotor and for the surface of the magnet insertion hole on the inner side of the rotor are each formed so that their size is reduced at the corner of the permanent magnet.

[0008] According to a second aspect of the invention, in the rotating electric machine of the first aspect, when a minimum width of the rotor core on an outer peripheral side of the non-magnetic portion W1 is set, a minimum width of the bridge portion W2 is set, and a minimum width of a core on the outer peripheral side of the rotor in the first corner of the magnet insertion hole W3 is set, W2 < W1 < W3 is preferably set.

[0009] According to a third aspect of the invention, in the rotating electric machine of the second aspect, when a maximum width of the bridge portion W4 is set, it is preferable to set W2 < W4 < W1 < W3.

[0010] According to a fourth aspect of the invention, in the permanent magnet type rotating electric machine of any one of the first to third aspects, the corner of the permanent magnet is chamfered in a curved shape or to have a planar surface. Each of the first corner of the magnet insertion hole and the second corner of the magnet insertion hole includes a curved surface positioned near the corner of the permanent magnet, the planar surface connected to the curved surface and forming the circumferential clearance portion, and a planar surface connected to the curved surface and forming the radial clearance portion.

[0011] According to a fifth aspect of the invention, in the permanent magnet type rotating electric machine of any one of the first to third aspects, the corner of the permanent magnet is chamfered in a curved shape or to have a planar surface. Preferably, each of the first corner of the magnet insertion hole and the second corner of the magnet insertion hole includes a planar surface positioned near the corner of the permanent magnet, a curved surface connected to the planar surface and forming the circumferential clearance portion, and a curved surface connected to the planar surface and forming the radial clearance portion.

[0012] According to a sixth aspect of the invention, in the permanent magnet type rotating electric machine according to the fourth or fifth aspect, the curvature of the curved surface is smaller than the curvature of the chamfer of the curved shape of the permanent magnet.

[0013] According to a seventh aspect of the invention, an electric drive device for a vehicle includes: the permanent magnet type rotating electric machine according to any one of the first to sixth aspects; and a power converter for supplying power for driving the rotating electric machine.

[0014] In accordance with a seventh aspect of the invention, a vehicle includes the electric drive device for a vehicle in accordance with the seventh aspect. Advantageous effects of the invention

[0015] According to the invention, it is possible to manufacture a permanent magnet type rotating electric machine that can withstand high speed rotation and output high power. Brief description of the drawings Fig. 1 is a schematic configuration diagram of a hybrid electric vehicle in which a rotary electric working machine according to the invention is mounted. Fig. 2 is a schematic configuration diagram of a circuit in a power converter 600 used to drive the rotating electric machine in accordance with the invention. Fig. 3 is a cross-sectional view of a first embodiment of the rotating electric machine in accordance with the invention. Fig. 4 is a view showing cross sections of a stator 230 and a rotor 250 of the Fig. 3 shown rotating electrical machine. Fig. 5 is a view explaining the reluctance moment. Fig. 6 is an enlarged view of the stator 230 and the rotor 250 in the Fig. 4 shown rotating electrical machine and corresponds to a magnetic pole. Fig. 7 is an enlarged view of a portion near an inter-magnet bridge portion 260 of the Fig. 6 shown rotating electrical machine. Fig. 8 is a view showing the distribution of mechanical stress during the rapid rotation of the Fig. 6 shown rotating electrical machine using lines of constant mechanical tension and corresponds to a half-magnetic pole, i.e. one half of one magnetic pole of the rotor. Fig. 9 is a view showing the distribution of magnetic flux lines when a stator winding 238 is not excited with a three-phase AC power, and corresponds to that of a magnetic pole of the Fig. 6 shown embodiment of the rotating electrical working machine in accordance with the invention. Fig. Fig. 10 is a view for further enlarging a corner of a permanent magnet 254 and a corner of a magnet insertion hole 253 at a periphery thereof and corresponds to that of a magnetic pole of the Fig. 6 or Fig. 7. (a) shows an example in which an inner surface of the corner of the magnet insertion hole 253 closest to the corner of the permanent magnet 254 is formed into a substantially curved arcuate surface, and in which each of the radially inner surfaces and circumferentially inner surfaces thereof connected to the arcuate arcuate surface is a planar surface. (b) shows an example in which the inner surface of the corner of the magnet insertion hole 253 closest to the corner of the permanent magnet 254 is formed into a planar arcuate surface, and in which each of the radially inner surfaces and circumferentially inner surfaces thereof connected to the planar arcuate surface is a substantially curved arcuate surface. Fig. 11 shows a modification example of the embodiment of the rotating electric machine in accordance with the invention, and is an enlarged cross-sectional view of the stator 230 and the rotor 250 corresponding to one magnetic pole in a configuration in which the three permanent magnets are provided for each magnetic pole and in which the inter-magnet bridge portion 260 is provided between adjacent magnets. Fig. 12 shows another modification example of the embodiment of the rotating electric machine in accordance with the invention, and is an enlarged cross-sectional view of the stator 230 and the rotor 250 corresponding to one of the magnetic poles in a configuration provided with the two magnet insertion holes for each magnetic pole, in which the two permanent magnets are inserted into each magnet insertion hole, and with the inter-magnet bridge portion 260 between the two magnet insertion holes. Fig. 13 shows still another modification example of the embodiment of the rotating electric machine in accordance with the invention, and is an enlarged cross-sectional view of the stator 230 and the rotor 250 corresponding to the one magnetic pole in a configuration in which the two permanent magnets 254 for the one magnetic pole are arranged in a V shape. Fig. Fig. 14 shows a second embodiment of the rotating electrical machine in accordance with the invention and is an enlarged view of a quarter of the total cross sections of the stator 231 and the rotor 251 in the rotating electrical machine having eight poles and 12 slots formed by the rotor of the rotating electrical machine shown in Fig. 4, wherein the concentrated winding stator has the 12 poles. Description of embodiments

[0016] In the following, Fig. 1 to Fig. 14 embodiments for carrying out the invention are described.

[0017] As described below, a rotating electric machine according to the invention can output high power and is thus suitable, for example, as a traction motor for an electric vehicle. The rotating electric machine according to the invention can be applied to an electric vehicle that travels solely by the rotating electric machine and to a hybrid electric vehicle that is driven by both an engine and the rotating electric machine. A description will be given below based on an example using the hybrid electric vehicle.

[0018] Fig. 1 is a schematic configuration diagram of a hybrid electric vehicle in which a rotating electric machine according to an embodiment of the invention is mounted. A vehicle 100 includes an engine 120, a first rotating electric machine 200, a second rotating electric machine 202, and a battery 180. The battery 180 supplies DC power to the rotating electric machines 200, 202 via a power converter 600 when driving forces generated by the rotating electric machines 200, 202 are required. The battery 180 is charged by converting the AC power from the DC power from the rotating electric machines 200, 202 into DC power when the vehicle is traveling in a regenerative state.The DC power is supplied and received between the battery 180 and the rotating electric machines 200, 202 via the power converter 600. Although not shown, a battery for supplying low-voltage power (such as 14-volt power) is also mounted in the vehicle to supply the DC power to a control circuit, which will be described later.

[0019] The torque generated by the engine 120 and the rotating electric machines 200, 202 is transmitted to the front wheels 110 via a transmission 130 and a differential gear 160. The transmission 130 is controlled by a transmission control device 134, and the engine 120 is controlled by an engine control device 124. The battery 180 is controlled by a battery control device 184. The transmission control device 134, the engine control device 124, the battery control device 184, the power converter 600, and an integrated control device 170 are connected by a communication line 174.

[0020] The integrated control device 170 is a control device that is superior to the transmission control device 134, the engine control device 124, the power converter 600, and the battery control device 184, and receives information indicating a state of the transmission control device 134, the engine control device 124, the power converter 600, and the battery control device 184 therefrom via the communication line 174. The integrated control device 170 generates a control command for each control device based on the acquired information. The thus generated control command is transmitted to each control device via the communication line 174.

[0021] The high-voltage battery 180 is configured by a secondary battery such as a lithium-ion battery or a nickel-hydrogen battery and outputs high-voltage direct current power of 250 volts to 600 volts or higher. The battery control device 184 outputs a charge / discharge condition of the battery 180 and a state of each unit cell battery constituting the battery 180 to the control integrated circuit 170 via the communication line 174.

[0022] When the integrated control device 170 determines that the battery 180 needs to be charged based on the information from the battery control device 184, it issues a power generation operation command to the power converter 600. Furthermore, the integrated control device 170 mainly manages the output torque of the engine 120 and the rotating electric machines 200, 202, arithmetically processes the total torque and a torque distribution ratio of the output torque of the engine 120 and the output torque of the rotating electric machines 200, 202, and sends the control command based on a result of the arithmetic processing to the transmission control device 134, the engine control device 124, and the power converter 600.The power converter 600 controls the rotating electric machines 200, 202 based on a torque command from the integrated controller 170 to cause them to produce the commanded torque output or the commanded generated power.

[0023] The power converter 600 is provided with a power semiconductor that forms a power converter for operating the rotating electrical machines 200, 202. The power converter 600 controls a switching operation of the power semiconductor based on the command from the integrated control device 170. The rotating electrical machines 200, 202 are operated as an electric motor or as a generator, respectively, through the switching operation of the power semiconductor.

[0024] When the rotating electric machines 200, 202 are operated as electric motors, the DC power from the high-voltage battery 180 is supplied to a DC terminal of the power converter in the power converter 600. The power converter 600 converts the DC power supplied thereto into three-phase AC power by controlling the switching operation of the power semiconductor and supplies it to the rotating electric machines 200, 202. Meanwhile, rotors in the rotating electric machines 200, 202 are driven to rotate by externally supplied torque, and the three-phase AC power generated in the stator windings in the rotating electric machines 200, 202 is generated when the rotating electric machines 200, 202 are operated as generators.The three-phase AC power thus generated is converted into DC power by the power converter 600, and the DC power is supplied to the high-voltage battery 180 to charge the battery 180.

[0025] Fig. 2 is a circuit diagram of the power converter 600 in Fig. 1. The power converter 600 is provided with a first power converter device for the rotating electric machine 200 and a second power converter device for the rotating electric machine 202. The first power converter device includes a power module 610, a first drive circuit 652 for controlling the switching operation of each of the power semiconductors 21 in the power module 610, and a current sensor 660 for detecting a current in the rotating electric machine 200. The drive circuit 652 is provided on a drive circuit board 650.

[0026] Meanwhile, the second power conversion device includes a power module 620, a second drive circuit 656 for controlling the switching operation of each of the power semiconductors 21 in the power module 620, and a current sensor 662 for detecting a current in the rotating electric machine 202. The drive circuit 656 is provided on a drive circuit board 654. A control circuit 648 provided on a control circuit board 646, a capacitor module 630, and a transceiver circuit 644 mounted on a connector board 642 are shared and used by the first power conversion device and the second power conversion device.

[0027] The power modules 610, 620 are operated by drive signals output from the respective drive circuits 652, 656. The power modules 610, 620 convert the DC power supplied from the battery 180 into three-phase AC power and supply the power to the stator windings, which are armature windings, of the respective rotating electrical machines 200, 202. In addition, the power modules 610, 620 each convert the AC power induced in the stator windings of the rotating electrical machines 200, 202 into DC power and supply it to the high-voltage battery 180.

[0028] As in Fig. As shown in Figure 2, the power modules 610, 620 each include a three-phase bridge circuit, wherein series circuits, each corresponding to the three phases, are electrically connected in parallel between one side of the positive electrode and one side of the negative electrode of the battery 180. Each of the series circuits includes the power semiconductor 21 for forming an upper arm and the power semiconductor 21 for forming a lower arm, wherein these power semiconductors 21 are connected in series. As shown in Fig. 2, the power module 610 and the power module 620 have substantially the same circuit configuration, and a description will be given here of the power module 610 as a representative example.

[0029] In this embodiment, an insulated gate bipolar transistor (IGBT) 21 is used as a switching power semiconductor element. The IGBT 21 includes three electrodes, namely, a collector electrode, an emitter electrode, and a gate electrode. A diode 38 is electrically connected between the collector electrode and the emitter electrode of the IGBT 21. The diode 38 includes two electrodes, namely, a cathode electrode and an anode electrode. The cathode electrode and the anode electrode are electrically connected to the collector electrode of the IGBT 21 and the emitter electrode of the IGBT 21, respectively, so that a direction from the emitter electrode to the collector electrode of the IGBT 21 is set as a forward direction.

[0030] A metal-oxide-semiconductor field-effect transistor (MOSFET) can be used as the switching power semiconductor element. The MOSFET contains three electrodes, namely a drain electrode, a source electrode, and a gate electrode. Since the MOSFET contains a parasitic diode between the source electrode and the drain electrode, with a direction from the drain electrode to the source electrode set as the forward direction, the diode 38 needs Fig. 2 is not intended.

[0031] The arms of each phase are configured such that the emitter electrode of the IGBT 21 is electrically connected in series with the collector electrode of the IGBT 21. In this embodiment, only one IGBT is shown for each of the upper and lower arms in each phase; however, the multiple IGBTs are actually and electrically connected in parallel because a current capacity to be controlled is large. For ease of description, the multiple IGBTs will be described below as one power semiconductor.

[0032] In the Fig. In the example shown in Figure 2, each of the upper and lower arms in each phase includes three IGBTs. The collector electrode of each IGBT 21 in the upper arm of each phase is electrically connected to the positive electrode side of the battery 180, and the source electrode of each IGBT 21 in the lower arm of each phase is electrically connected to the negative electrode side of the battery 180. A midpoint between the arms in each phase (a connected portion between the emitter electrode of the IGBT on the upper arm side and the collector electrode of the IGBT on the lower arm side) is electrically connected to the armature winding (stator winding) of the corresponding phase in a corresponding one of the rotating electric machines 200, 202.

[0033] Each of the drive circuits 652, 656 forms a drive section for controlling the corresponding one of the power converter devices 610, 620 and generates a drive signal for driving the IGBT 21 based on a control signal output from the control circuit 648. The drive signal generated in each of the drive circuits 652, 656 is output to the gate of each power semiconductor element in the corresponding one of the power modules 610, 620. Each of the drive circuits 652, 656 is provided with six integrated circuits, each of which generates a drive signal supplied to the gate of each of the upper and lower arms in each phase. The six integrated circuits form a block.

[0034] The control circuit 648 forms a control section for each of the power converter devices 610, 620 and is configured by a microcomputer that generates the control signal (a control value) for operating (turning on / off) the plurality of switching power semiconductor elements. The control circuit 648 receives a torque command signal (a torque command value) from the higher-level control device, a sensor output from each of the current sensors 660, 662, and a sensor output from a rotation sensor mounted in each of the rotating electrical machines 200, 202. The control circuit 648 calculates the control value based on these input signals and outputs the control signal to control the switching timing for the drive circuits 652, 656.

[0035] The transceiver circuit 644, which is attached to the connector board 642, is used to electrically connect the power converter 600 to the external control device and transmits / receives via the communication line 174 in Fig. 1 Information to / from another device. The capacitor module 630 forms a smoothing circuit for suppressing a fluctuation in a DC voltage caused by the switching operation of the IGBT 21 and is electrically connected in parallel to a DC terminal in each of the first power module 610 and the second power module 620. <Ausführungen der rotierenden elektrischen Arbeitsmaschine in Übereinstimmung mit der Erfindung>

[0036] Fig. 3 is a cross-sectional view of an embodiment of the rotating electric machine in accordance with the invention shown in Fig. 1 is used as the rotating electric machine 200. The rotating electric machine 200 and the rotating electric machine 202 have substantially the same structure, and the structure of the rotating electric machine 200 will be described below as a representative example. Note that the structure described below need not be adopted for both rotating electric machines 200, 202, but may be adopted for either of the rotating electric machines 200, 202.

[0037] A stator 230 is supported in a housing 212, the stator 230 including a stator core 232 and a stator winding 238. A rotor 250 is rotatably supported on an inner peripheral side of the stator core 232 via a gap 222. The rotor 250 includes a rotor core 252 fixed to a shaft 218, a permanent magnet 254, and an abutment plate 226 formed of a non-magnetic body. The housing 212 has paired bearing bridges 214, each of which is provided with a bearing 216, and the shaft 218 is rotatably supported by these bearings 216.

[0038] The shaft 218 is provided with a resolver 224 to detect a position of a pole and a speed of the rotor 250. The control circuit 648, which is Fig. 2, receives the output from the resolver 224. The control circuit 648 outputs the control signal to the drive circuit 652 based on the received output. The drive circuit 652 outputs the drive signal based on the control signal to the power module 610. The power module 610 performs the switching operation based on the control signal and converts the DC power supplied from the battery 180 into the three-phase AC power. The three-phase AC power is supplied to the stator winding 238, which in Fig. 3, thereby generating a rotating magnetic field in the stator 230. A frequency of a three-phase alternating current is controlled based on an output value of the resolver 224, and a phase of the three-phase alternating current with respect to a rotational position of the rotor 250 is also controlled based on the output value of the resolver 224.

[0039] Fig. 4 is a view showing cross sections of the stator 230 and the rotor 250 shown in Fig. 3 and is also a cross-sectional view along the line AA of Fig. 3. The housing 212, the shaft 218 and the stator winding 238 are in Fig. 4 not shown. The stator winding in a slot 237 is Fig. 5 not shown.

[0040] A number of slots 237 and a number of teeth 236 are arranged at equal intervals over an entire inner circumference of the stator core 232. In Fig. 4, not all slots and teeth are designated by the reference numerals, but only parts thereof are designated by the reference numerals. A slot insulation material (not shown) is provided in the slot 237 and is wound over a plurality of U-phase, V-phase, and W-phase windings, which form the stator winding 238 in Fig. 3. In this embodiment, the 48 grooves 237 are formed at equal intervals.

[0041] A vicinity of an outer periphery of a rotor core 252 is arranged along a circumferential direction with 16 magnet insertion holes 253, into each of which a rectangular magnet is inserted. Each magnet insertion hole 253 is formed along an axial direction, and the permanent magnet 254 (254a, 254b) is embedded and fixed in the magnet insertion hole 253 by an adhesive or the like. The paired magnet insertion holes 253 and the paired permanent magnets 254 form a magnetic pole. Each pair of magnet insertion holes 253 is set to have a wider circumferential width than each pair of permanent magnets 254, and a hole space 257 on the outer side of the magnetic pole of the permanent magnet 254 functions as a magnetic gap. The hole space 257 may be filled with the adhesive or hardened by a molding resin so as to be integrated with the permanent magnet 254.The permanent magnet 254 acts as a field magnetic pole of the rotor 250, and this embodiment is configured to have the eight poles.

[0042] A magnetization direction of the permanent magnet 254 is set as a radial direction, and the magnetization direction is reversed by each field pole. In other words, if the surface of the permanent magnet 254a on the stator side is an N pole and a surface thereof on the axial side is an S pole, a surface of the permanent magnet 254b on the stator side is the S pole, and a surface thereof on the axial side is the N pole. The paired permanent magnets 254a and the paired permanent magnets 254b, respectively, form one magnetic pole and are arranged alternately in the circumferential direction.

[0043] The permanent magnet 254 can be inserted into the magnet insertion hole 253 after being magnetized, or can be magnetized by applying a strong magnetic field to it after being inserted into the magnet insertion hole 253 of the rotor core 252. After the permanent magnet 254 is magnetized, it becomes a strong magnet. Thus, a strong attractive force is generated between the rotor core 252 and the permanent magnet 254 during the attachment of the permanent magnet 254, which disrupts the assembly work if a magnet is polarized before the permanent magnet 254 is attached to the rotor 250. In addition, the strong attractive force of the permanent magnet 254 may cause dust such as iron powder to adhere to the permanent magnet 254.Thus, the permanent magnet 254 is preferably magnetized after being inserted into the rotor core 252, taking into consideration the productivity of the rotating electric machine.

[0044] A neodymium-based or samarium-based sintered magnet, a ferrite magnet, a neodymium-based bonded magnet, or the like can be used as the permanent magnet 254. The residual magnetic flux density of the permanent magnet 254 is approximately 0.4 to 1.3 T.

[0045] When the three-phase alternating current flows through the stator winding 238, thereby generating the rotating magnetic field in the stator 230, the rotating magnetic field acts on the permanent magnets 254a, 254b of the rotor 250 to generate a torque. The torque is expressed by a product of a component of the magnetic flux from the permanent magnet 254 interlinked with each winding and a component orthogonal to a linkage magnetic flux of the alternating current flowing through each winding.Here, if an AC waveform is considered to be a sinusoidal waveform, a product of a fundamental component of the interlinkage magnetic flux and a fundamental component of the AC current becomes a time-averaged component of torque, and a product of a harmonic component of the interlinkage magnetic flux and the fundamental component of the AC current becomes a torque ripple, which is a harmonic component of torque. That is, to reduce the torque ripple, the harmonic component of the interlinkage magnetic flux must be reduced. In other words, since a product of the interlinkage magnetic flux and an angular acceleration of the rotor rotation corresponds to an induced voltage, reducing the harmonic component of the interlinkage magnetic flux is essentially the same as reducing the harmonic component of the induced voltage.

[0046] Fig. 5 is a view for explaining the reluctance torque. Generally, an axis of magnetic flux passing through the center of the magnet is called a d-axis, while an axis of magnetic flux flowing from one region between the poles of the magnets to another region between the poles of the magnet is called a q-axis. At the same time, a core portion in the center of the region between the poles of the magnets is called an auxiliary salient pole portion 259. The permanent magnet 254 provided in the rotor 250 has substantially the same magnetic permeability as air. Thus, as viewed from the stator side, the d-axis is magnetically recessed, while the q-axis is magnetically protruded. Accordingly, the q-axis core portion is called a salient pole.The reluctance torque is generated by a difference in the transfer capacity (magnetic inductance) of the magnetic flux between the d-axis and the q-axis, i.e. by a salient pole ratio.

[0047] Fig. 6 is an enlarged cross-sectional view of the stator 230 and the rotor 250 in the Fig. 4 and corresponds to one magnetic pole. The rotor core 252 is formed with the magnetic gap 257 on the outer side of the magnetic pole of the permanent magnet 254 to reduce cogging torque or torque pulsation during excitation. Moreover, a radial thickness of the magnetic gap 257 is smaller than a radial thickness of the permanent magnet 254, and a magnetic pole end pressing portion 264, which is a part of the rotor core on an inner peripheral side of the magnetic gap 257, restricts the movement of the permanent magnet 254 in the circumferential direction. Furthermore, a magnetic pole outer portion 256 on the outer side in the radial direction of the magnet insertion holes 253, into which the permanent magnet 254 is inserted, is set so that a width W1 of a magnetic pole end bridge portion 258 becomes the smallest in a radial dimension.

[0048] When the width W1 of the magnetic pole end bridge portion 258 is reduced, the magnetic flux from the permanent magnet flowing through a magnetic path in the rotor is reduced, and the increased magnetic flux reaches the stator side. Thus, the magnetic torque can be increased. Accordingly, the width W1 of the magnetic pole end bridge portion 258 is preferably reduced as much as possible to withstand the mechanical stress generated during rotor rotation.

[0049] Fig. 7 is an enlarged view of an inter-magnet bridge section 260 (a region labeled B) of the Fig. 6. The inter-magnet bridge portion 260 is provided between the paired permanent magnets 254 such that the magnetic pole outer portion 256 of the rotor core, positioned on the outer peripheral side of the permanent magnet 254, is mechanically connected to a magnetic pole inner portion 263 of the rotor core on the inner peripheral side. Furthermore, a circumferential clearance portion 261 and a radial clearance portion 262 are set in each of the four corners of the magnet insertion holes 253 positioned at both ends of the inter-magnet bridge portion 260 such that the corner of the permanent magnet 254 does not contact the rotor core even when the magnet most closely approaches the bridge portion in terms of dimensional tolerance.In this case, the thickness T1 of the circumferential gap portion 261 is set to be reduced at the center of the permanent magnet 254 and at the corner of the permanent magnet 254, and to be maximum therebetween. A thickness T2 of the radial gap portion 262 is set to be reduced at the center of the permanent magnet 254 and at the corner of the permanent magnet 254, and to be maximum therebetween. Moreover, the movement of the permanent magnet 254 in the circumferential direction is restricted similarly to the aforementioned magnetic pole end pressing portion 264 on the inner peripheral side of the magnetic gap 257 in the center of the inter-magnet bridge portion 260. Thus, favorable assembleability can be achieved without using a new component.

[0050] It is noted that the forms of the Fig. 7 shown above mentioned four corners based on Fig. 10(a), which will be described later.

[0051] By adopting such a configuration, it is possible to prevent damage to the rotor core 252 and its deformation caused when the corner of the magnet contacts the rotor core, and it is also possible to reduce the concentration of stress generated at both ends of the inter-magnet bridge portion 260. Accordingly, the rotor 250 can achieve high-speed rotation.

[0052] In this embodiment, a line connecting between the circumferential clearance portion 261 and the radial clearance portion 262 has a larger radial dimension than the corner of the magnet; however, the same effect can be obtained by combining a straight line and an arc as described below.

[0053] Generally, when the inter-magnetic bridge portion 260 is provided, the magnetic flux of the permanent magnet 254 passes through the inter-magnetic bridge portion 260, and a magnetic flux path in the rotor is closed. Accordingly, the effective magnetic flux coupled at the center of a rotor magnetic pole to an opposite stator magnetic pole is reduced, thereby deteriorating performance. Thus, a width W2 of a narrowest part of the inter-magnetic bridge portion 260 is preferably as small as possible.

[0054] Furthermore, as described above, a width W4 at the center of the inter-magnet bridge portion 260 is set to be slightly larger than W2; however, the width W4 is also preferably as small as possible. When the width W4 at the center of the inter-magnet bridge portion 260 is small, the permanent magnets inserted into the two adjacent magnet insertion holes 253 approach each other, thereby suppressing a decrease in the magnetic flux density at the center of the magnetic pole. The rotor can be designed to satisfy such a relationship between W2 and W4 due to a structure of the rotor according to the invention.

[0055] A permanent magnet need not be exactly rectangular, but can be substantially rectangular. In this case, the cross-sectional shape of the magnet insertion hole is also set to be substantially rectangular, corresponding to the cross-sectional shape of the permanent magnet. When the shape of the permanent magnet is changed from rectangular, the magnetic flux density distribution can also be changed.

[0056] In this embodiment, the minimum width W1 of the magnetic pole end bridge portion 258, the minimum width W2 of the inter-magnet bridge portion 260, and a width W3 of the rotor core on the outer peripheral side of the radial gap portion 262 set W2 < W1 < W3. This relationship between W1, W2, and W3 can be achieved by adopting the structure of the rotor having the above-mentioned characteristic and will be described below.

[0057] The mechanical stress generated by a centrifugal force of the rotor is increased at a root of the inter-magnet bridge portion 260 on the outer peripheral side of the rotor, that is, at the corners of the two adjacent magnet insertion holes 253 on the outer peripheral side of the rotor with the inter-magnet bridge portion 260 therebetween, as well as on the side of the magnetic pole end bridge portion 258. However, in a Fig. 6, the mechanical stress in the magnetic pole end bridge portion 258 is greatest by the lever law because the inter-magnet bridge portion 260 connecting the magnetic pole outer portion 256 and the magnetic pole inner portion 263 is provided between the two permanent magnets 254 and between the two magnet insertion holes 253 into which the two permanent magnets 254 are inserted.

[0058] Accordingly, in order to prevent leakage of the magnetic flux, it is preferable from the performance point of view alone that the magnetic pole end bridge portion 258 has the reduced minimum width W1 and is brought to a state of magnetic saturation; however, because of the high concentration of stress during high-speed rotation, it requires a sufficient thickness to withstand the stress.

[0059] Although the minimum width W2 of the inter-magnet bridge portion 260 is substantially the same as the minimum width W1 of the magnetic pole end bridge portion 258, a degree of stress concentration thereon is smaller than that of the magnetic pole end bridge portion 258 as described above, so W2<W1 can be set. Meanwhile, a width W3 of the rotor core on the outer peripheral side of the radial gap portion 262 serves as a magnetic path through which the magnetic flux of the permanent magnet 254 passes when interlinked with each winding, so it is desired not to be saturated. Accordingly, W3>W1 is set.

[0060] As described above, due to the structure of the rotor according to the invention, the width W4 at the center of the inter-magnet bridge portion 260 can be set slightly smaller than W2. In other words, W4 < W1 < W3 is set. With such a structure, a distance between the two adjacent permanent magnets can be reduced and the magnetic flux density at the center of the rotor magnetic pole can be kept high.

[0061] Fig. 8 is a half-magnetic pole model to illustrate the distribution of mechanical stress during the rapid rotation of the magnets in Fig. 6, corresponding to a half magnetic pole, that is, one half of one magnetic pole of the rotor. Stress is concentrated at the magnetic pole-end bridge portion 258 and both ends of the inter-magnetic bridge portion 260, where the lines of constant stress are concentrated compared to other parts. However, since W2 < W1 < W3 is set due to the configuration as described above, the stress is distributed without being locally concentrated at the magnetic pole-end bridge portion 258 and both ends of the inter-magnetic bridge portion 260.

[0062] In the above-mentioned embodiment of the rotating electric machine according to the invention, the two permanent magnets 254 corresponding to one magnetic pole are linearly aligned. Accordingly, the stress generated at both ends of the inter-magnet bridge portion 260 can be substantially balanced, and the concentration of stress therein can also be avoided. Thus, although such an alignment is preferable in terms of strength, an effect of the invention can be obtained even if the permanent magnets 254 are not linearly aligned.

[0063] Fig. 9 shows a distribution of the magnetic flux lines when the stator winding 238 is not excited with the three-phase AC power, being directed to one magnetic pole of the Fig. 6 of the rotating electric machine according to the invention. As described above, in the configuration, the dimensions of W1, W2, and W3 are set to establish the relationship W2 < W1 < W3. From such a configuration, it can be seen that the magnetic pole end bridge portion 258 and the inter-magnet bridge portion 260 are saturated by the minimum magnetic flux of the magnetic flux generated by the permanent magnet 254, and that most of the magnetic flux from the magnetic pole outer portion 263 of the rotor core is coupled to the stator core 232 and interlinked with the stator winding 238.

[0064] Fig. Fig. 10 is an enlarged view of one corner of the permanent magnet 254 and a part of the magnet insertion hole 253 at the periphery thereof, shown in Fig. 7 or Fig. 8. The four corners of the two magnet insertion holes 253 holding the inter-magnet bridge portion 260 therebetween have the same shape, and of the four corners, in particular, an enlarged lower right part of the permanent magnet 254 in Fig. 8 is shown as a representative example.

[0065] The corner of the permanent magnet is chamfered in a curved shape or in a planar shape to a degree that the shape has no influence on a magnetic characteristic. Fig. Figure 10 shows an example in which the corner of the permanent magnet is curved. Due to this corner shape, the inner surface of the corner of the magnet insertion hole opposite to the corner can have a smooth curve, thereby dispersing the stress generated by the rotation of the rotor.

[0066] In addition, since the curvature of the inner surface of the corner of the magnet insertion hole is partially configured by linear and curved lines, as shown in Fig. 10, a difference between the maximum width W4 of the inter-magnet bridge portion and the minimum width W2 of the inter-magnet bridge portion in the circumferential gap portion 261 is reduced, wherein W2 and W4 may have small values.

[0067] In a Fig. In the example shown in Figure 10(a), a part of the inner surface of the corner of the magnet insertion hole 253 positioned closest to the corner of the permanent magnet 254 has a curved surface (shown in the curved shape in the drawing) that is gentler than the curved shape of the corner of the permanent magnet 254, and the inner surfaces of the circumferential clearance portion 261 and the radial clearance portion 262 connecting to the part are each configured by a planar surface (shown by the straight line in the drawing). It is noted that in Fig. 7 described above, the shape of the inner surface of the corner of the magnet insertion hole 253 based on Fig. 10(a).

[0068] In Fig. 10(b), the part of the inner surface of the corner of the magnet insertion hole 253 positioned closest to the corner of the permanent magnet 254 has the planar shape (shown by the linear line in the drawing), and the inner surfaces of the circumferential clearance portion 261 and the radial clearance portion 262 connecting to the part are each configured by a substantially arcuately curved surface (shown by the curved line in the drawing).

[0069] If the corner of the permanent magnet 254 is chamfered in the planar surface and if the corner of the magnet insertion hole 253 opposite to the corner of the permanent magnet 254 has the planar surface, the planar surface of the corner of the magnet insertion hole 253 is designed to have the larger width than the planar surface of the corner of the permanent magnet 254.

[0070] Similarly, if the corner of the permanent magnet 254 is chamfered in the curved surface and if the corner of the magnet insertion hole 253 opposite to the corner of the permanent magnet 254 has the curved surface, the curved surface of the corner of the magnet insertion hole 253 is designed to have the larger width than the curved surface of the corner of the permanent magnet 254, and the curvature of the curved surface of the corner of the magnet insertion hole 253 is designed to be smaller than the curvature of the curved surface of the corner of the permanent magnet 254.

[0071] Fig. 11 shows a modification example of the rotating electric machine according to the invention and is an enlarged cross-sectional view of the stator 230 and the rotor 250 corresponding to one magnetic pole in a configuration in which the three permanent magnets are provided for each magnetic pole, and in which the inter-magnet bridge portion 260 is provided between the two adjacent magnet insertion holes into each of which the magnet is inserted. Even if the invention adopts the configuration in which the plurality of permanent magnets are provided for each magnetic pole and in which the inter-magnet bridge portion 260 is provided between the adjacent permanent magnets, that is, the configuration in which the plurality of inter-magnet bridge portions 260 are provided for each magnetic pole, the stress during high-speed rotation can be reduced.When the magnetic pole is provided with multiple inter-magnet bridge sections 260, a part of the rotor core on the outer side of the permanent magnet is firmly connected to a part of the rotor core on the rotor axis side of the permanent magnet. Accordingly, even faster rotation can be expected.

[0072] Fig. 12 is an enlarged view of the stator 230 and the rotor 250 corresponding to one magnetic pole in another modification example of the rotating electric machine according to the invention. In this modification example, two magnet insertion holes 253 are provided for each magnetic pole, and two permanent magnets 254 are inserted into each magnet insertion hole 253. Even if the plurality of permanent magnets 254 are provided for the one magnetic pole, there is no need to provide the inter-magnet bridge portion 260 between adjacent ones of the magnets as long as the stress generated during high-speed rotation does not exceed the allowable stress.Furthermore, by dividing the permanent magnet 254 into a plurality of permanent magnets, the eddy current flowing through a surface of the permanent magnet 254 can be reduced, thereby reducing heat generation and improving efficiency. Although the one magnet insertion hole in FIG. Fig. 12 the permanent magnet is inserted which is divided into two parts, accordingly the permanent magnet which is divided into three or more parts can be inserted therein.

[0073] Fig. 13 shows yet another modification example of the rotating electric machine according to the invention. This drawing also shows the enlarged stator 230 and the enlarged rotor 250 corresponding to one magnetic pole. Even if the plurality of permanent magnets 254 are not aligned linearly as described above but are aligned in a V shape, similar to the above-mentioned embodiment, by adopting the above-mentioned structure of the rotating electric machine according to the invention, the rotating electric machine capable of high-speed rotation and high-power output can be realized.

[0074] Fig. Fig. 14 shows a second embodiment of the rotating electric machine in accordance with the invention and shows the rotating electric machine having eight poles and 12 slots formed by the rotor of the rotating electric machine shown in Fig.4 and configured by a concentrated winding stator 231 having 12 poles. The drawing shows a quarter of each of the enlarged cross sections of the stator 231 and the rotor 250. Even if the stator 230 is concentrated wound, the structure of the rotor in the rotating electric machine according to the invention can be adopted; thus, the same effect can be obtained by the rotating electric machine having the concentrated winding stator. In other words, the invention does not depend on a type of stator.

[0075] So far, the examples of the invention have been described; however, the invention is not limited to these embodiments and modification examples. Those skilled in the art can implement various modifications without compromising the characteristics of the invention. In particular, various combinations are possible between the number of the two or more magnet insertion holes described above and the number of permanent magnets inserted into each magnet insertion hole, and such a combination is appropriately determined in accordance with a specification of the rotating electrical machine.

[0076] The disclosure of the following basic application, the priority of which is claimed, is incorporated herein in its entirety by reference.

[0077] Japanese Patent Application No. 2011-220056 (filed on October 4, 2011).

Claims

[1] A permanent magnet type rotating electric machine comprising a stator (230) and a rotor (250) arranged across a gap (222) corresponding to the stator (230), wherein the rotor (250) comprises: a rotor core (252) having a plurality of magnet insertion holes (253) for each magnetic pole, each of which has a substantially rectangular cross-section; and a permanent magnet inserted into each of the magnet insertion holes (253), a non-magnetic portion is formed at both ends in a circumferential direction of each of the plurality of magnet insertion holes (253) provided for each magnetic pole of the rotor (250), a bridge portion (260) is provided between the adjacent ones of the plurality of magnet insertion holes (253) to mechanically connect a rotor core portion on the outside of the magnet insertion hole (253) to a rotor core portion on the inside of the magnet insertion hole (253), in a first corner, which is a corner between a surface of the magnet insertion hole (253) on the side of the bridge portion (260) and a surface of the magnet insertion hole (253) on the outside of the rotor (250), and in a second corner, which is a corner between the surface of the magnet insertion hole (253) on the side of the bridge portion (260) and a surface of the magnet insertion hole (253) on the inside of the rotor (250), circumferential clearance portions (261) and radial clearance portions (262) are provided, so that a corner of the long permanent magnet with a rectangular cross-section inserted into the magnet insertion hole (253) does not contact the surfaces of the magnet insertion hole (253) on the side of the bridge portion (260), on the outside of the rotor (250), and on the inside of the rotor (250), and wherein the radial clearance portion (262) for the surface of the magnet insertion hole (253) on the side of the bridge portion (260) is formed such that its size is reduced at the corner of the permanent magnet, while the circumferential clearance portions (261) for the surface of the magnet insertion hole (253) on the outside of the rotor (250) and for the surface of the magnet insertion hole (253) on the inside of the rotor (250) are each formed such that their size is reduced at the corner of the permanent magnet, wherein then, when a minimum width of the rotor core (252) is set on an outer peripheral side of the non-magnetic portion W1, a minimum width of the bridge portion (260) W2 is set, and a minimum width of a core on the outer peripheral side of the rotor (250) in the first corner of the magnet insertion hole (253) W3 is set, the following relationship is satisfied: W2 <W1<W3, and wherein, when a maximum width of the bridge section (260) W4 is set, the following relationship is satisfied: W2 <W4<W1<W3. [2] A permanent magnet type rotating electric machine according to claim 1, wherein the corner of the permanent magnet is chamfered in a curved shape or in a planar shape, and each of the first corner of the magnet insertion hole (253) and the second corner of the magnet insertion hole (253) includes a curved surface positioned near the corner of the permanent magnet, a planar surface connected to the curved surface and forming the circumferential gap portion, and a planar surface connected to the curved surface and forming the radial gap portion. [3] A permanent magnet type rotating electric machine according to claim 1, wherein the corner of the permanent magnet is chamfered in a curved shape or in a planar shape, and each of the first corner of the magnet insertion hole (253) and the second corner of the magnet insertion hole (253) includes a planar surface positioned near the corner of the permanent magnet, a curved surface connected to the planar surface and forming the circumferential gap portion, and a curved surface connected to the planar surface and forming the radial gap portion. [4] A permanent magnet type rotating electric machine according to claim 2 or 3, wherein the curvature of the curved surface is smaller than the curvature of the chamfer of a curved shape of the permanent magnet. [5] An electric drive device for a vehicle, the electric drive device comprising: the permanent magnet type rotating electric machine according to any one of claims 1 to 4; and a power converter to supply power to control the electrical machine. [6] A vehicle comprising the electric drive device for a vehicle according to claim 5.

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