CN113016121A

CN113016121A - Rotating electrical machine and electric auxiliary machine system for automobile

Info

Publication number: CN113016121A
Application number: CN201980074762.7A
Authority: CN
Inventors: 田子一农; 辻裕司; 金泽宏至; 川崎省三
Original assignee: Hitachi Astemo Ltd
Current assignee: Showa Corp; Hitachi Astemo Ltd
Priority date: 2018-11-22
Filing date: 2019-11-08
Publication date: 2021-06-22
Also published as: WO2020105465A1; JP2020089039A

Abstract

The technical problem of the invention is to reduce the torque ripple of the rotating electric machine by using reluctance torque. The rotor core of the embedded permanent magnet type rotating motor of the invention comprises: a magnet insertion hole on each magnetic pole portion and longer in a circumferential direction than in a radial direction; a magnet stopper portion on an inner peripheral side of both ends of the magnet insertion hole; a gap on the outer peripheral side of the magnet stopper; a bridge portion on the outer peripheral side of the gap; q-axis cores between adjacent magnet insertion holes; a magnet receiving portion of a rectangular shape between the magnet stopper portions at both ends of the magnet insertion hole; an umbrella-shaped core body on the outer periphery side of the magnet housing part; a first connection between the umbrella core and the bridge; and a second connecting portion between the q-axis core and the bridge portion. The width Wb of the bridge portion is smaller than the radial length Tmg/2 of the magnet housing portion. The central angle of Wq is in the range of 0.4 to 0.9 times of pi/(3 times of pole number).

Description

Rotating electrical machine and electric auxiliary machine system for automobile

Technical Field

The present invention relates to a rotating electric machine and an electric auxiliary machine system for an automobile.

Background

In recent years, with the shift of a hydraulic system to an electric system and a trend toward an expansion of the market of hybrid cars and electric cars, the installation rate of electric power steering (hereinafter abbreviated as EPS) devices and electric brake devices is rapidly increasing. In addition, in the background of widespread use of vehicles in which some driving operations such as idling stop and braking are automated, the driving comfort is improved and the silencing in the vehicle cabin is advanced.

As excitation sources caused by the motor in association with vibration and noise in the vehicle cabin, there are torque fluctuation components (cogging torque and torque ripple) of the motor and electromagnetic excitation force generated between the stator and the rotor of the motor. The vibration energy generated by the torque variation component is transmitted into the vehicle compartment through the output shaft of the motor, and the vibration energy generated by the electromagnetic excitation force is transmitted into the vehicle compartment through the mechanical components of the EPS device and the like. As these vibration energy is transmitted into the vehicle cabin, vibration and noise occur in the vehicle cabin.

For example, in the EPS device, the motor vibration caused by cogging torque, torque ripple, and electromagnetic excitation force of the motor is felt on the hand of the driver through the steering wheel due to the motor assisting the steering wheel operation. Further, the motor vibration caused by the torque ripple and the electromagnetic excitation force may generate noise by the steering wheel, or may generate noise by reaching the vehicle interior front panel through another path.

In order to suppress this, in general, a motor used in an EPS device is required to suppress the cogging torque to 1/1000 smaller than the assist torque and to suppress the torque ripple to 1/100 smaller than the assist torque. Further, the minimum order of the principal spatial mode of the electromagnetic excitation force is preferably greater than 2.

On the other hand, when the automatic driving is introduced, it is assumed that the steering wheel and the EPS device are not mechanically coupled as in the conventional case but are connected by an electric signal. In this case, it is considered that the vibration and noise via the steering wheel disappear, the motor vibration allowable upper limit value is relaxed, and in the case of unmanned driving, the motor vibration allowable upper limit value is further relaxed. In the case of the automated driving, there is a mechanical or electrical difference between the connection of the steering wheel and the EPS device when the driver steers, and it is considered that the motor vibration allowable upper limit value of the latter is more moderate than the former.

Further, regarding the torque ripple of the motor, a component of order 6, which is 6 times the logarithm of the NS magnetic pole, is a basic order, and a component of order 12 or more is a high order component. Therefore, it is considered that the variation of the allowable upper limit value of the motor vibration is increased and eased with the introduction of the automatic driving. In addition, when the steering wheel and the EPS device are mechanically connected, it is also considered that the allowable upper limit value of the torque ripple high-order component is relaxed.

Here, as a motor used in an EPS device, a permanent magnet brushless motor (hereinafter referred to as a "permanent magnet type rotating electrical machine") is generally used from the viewpoint of downsizing and reliability. In general, a permanent magnet type rotating electrical machine includes a surface magnet type (SPM) having an excellent output density and an embedded magnet type (IPM) having an excellent magnet cost, and magnets separated into a number corresponding to the number of poles are often used in view of reducing the magnet cost. .

For example, the embedded magnet type generally uses an integrated rotor core having a magnet housing space. Because the integral rotor core has higher rotor magnetic pole manufacturing precision, the air gap length between the rotor magnetic pole and the stator can be shortened. Although flux leakage at the bridge portion of the magnet housing space makes the torque lower than that of the surface magnet type, the reduction of the torque can be suppressed by shortening the air gap length. Further, since the rectangular magnet can be used, the magnet cost can be reduced.

Here, when a torque ripple allowable upper limit value that is as strict as in the conventional art is required, a motor having a protruding magnetic pole shape that uses only magnet torque is also used in the case of IPM. The reason for this is that when reluctance torque is used, the torque ripple is about 5%, and the deviation from the torque ripple allowable upper limit value is large.

In addition, in the EPS device, since the magnetic flux distribution around the magnetic pole is symmetrical in both rotational directions due to the bidirectional rotation in the forward direction and the reverse direction, the magnetic pole having a symmetrical shape is used.

Patent document 1 describes a conventional brushless motor using reluctance torque. In the brushless motor described in patent document 1, the winding is a short-pitch winding, torque ripple is reduced compared with a full-pitch winding, and in a rotor whose outer periphery is a perfect circle, "a rotor including a plurality of magnetically assisted salient pole portions formed between magnetic poles of a magnet and a first magnetic gap provided on a side surface of the magnet" is provided, and "a second magnetic gap is formed in the magnetically assisted salient pole portion of the rotor so as to be symmetrical with respect to a d axis and asymmetrical with respect to a q axis" (claim).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-154445

Disclosure of Invention

Technical problem to be solved by the invention

In the brushless motor disclosed in patent document 1, there is room for improvement in torque ripple.

Technical scheme for solving technical problem

One aspect of the present invention is a permanent magnet embedded rotating electrical machine including a rotor core, the rotor core including: a magnet insertion hole located at each magnetic pole portion and longer in a circumferential direction than in a radial direction; a magnet stopper portion on an inner peripheral side of both ends of the magnet insertion hole; a gap on an outer peripheral side of the magnet stopper; a bridge portion on an outer peripheral side of the gap; a q-axis core body between the adjacent magnet insertion holes; a magnet receiving portion of a rectangular shape between magnet stopper portions at both ends of the magnet insertion hole; an umbrella-shaped core body on the outer peripheral side of the magnet housing section; a first connection between the umbrella core and the bridge; and a second connection portion between the q-axis core and the bridge portion. The outer peripheral portion of the rotor core sandwiched between two imaginary q-axis direction straight lines passing through both ends of the minimum width Wq in the q-axis vertical direction of the q-axis core is positioned on a circle having a radius substantially coincident with the rotor radius with the rotation axis as the center. The outer peripheral profiles of the core of the umbrella-shaped core, the first connecting portion and the bridge portion are formed by circular arcs. The width Wb of the bridging portion is smaller than the radial length Tmg/2 of the magnet accommodating portion. The radial thickness Hc of the center of the magnetic pole of the umbrella-shaped core body is within the range of 0.5-1.0 times of the radial thickness Hcm of the imaginary arc when the central angle of the arc is enlarged to the pole distance end. The central angle of Wq is in the range of 0.4-0.9 times of pi/(3 times of pole number). And the Wq is within the range of 1.15-2.5 times of the Hc.

Effects of the invention

According to one embodiment of the present invention, torque ripple can be reduced using reluctance torque.

Drawings

Fig. 1 is a cross-sectional view in a rotation plane of a permanent magnet type rotating electric machine according to embodiment 1.

Fig. 2 is a perspective view of the stator core portion of fig. 1.

Fig. 3 is a sectional view of the rotor according to embodiment 1.

Fig. 4 is an enlarged view of the vicinity of the magnetic pole in the cross section of the rotor according to embodiment 1.

Fig. 5 is an explanatory diagram showing a phase sequence of the coils arranged in the slots.

Fig. 6 is an explanatory diagram of the structure of the drive circuit of the two-system winding.

Fig. 7A is an explanatory diagram of another configuration example of the drive circuit shown in fig. 6.

Fig. 7B is a conceptual diagram of a coil configuration of four-system windings.

Fig. 8 is an explanatory diagram of magnetic fluxes that generate reluctance torque and magnet torque.

Fig. 9 is an explanatory diagram of torque generated in the circuit configuration diagram shown in fig. 5.

Fig. 10 is an explanatory diagram showing calculated values of the torque ripple 6 th order component of the circuit configuration shown in fig. 5.

Fig. 11 is a diagram illustrating the shape range of the present invention.

Fig. 12A is an explanatory diagram of the definition of the shape dimension.

Fig. 12B is an explanatory diagram of an enlarged view of the vicinity of the bridge portion of fig. 12A and the definition of the shape and size.

Fig. 13 is an explanatory diagram of a start point of pulsation.

Fig. 14 is an explanatory diagram of the phase of the pulsation 12 order component.

Fig. 15 is an explanatory diagram of Wq and a pulsation waveform.

Fig. 16 is an explanatory diagram of the relationship between Hc and the normalized magnet flux density distribution of the air gap.

Fig. 17 is an explanatory diagram of Hc and the pulsation waveform.

Fig. 18 is an explanatory diagram of calculated values of a torque ripple 12-order component and a torque ripple 6-order component in embodiment 1.

Fig. 19A is an enlarged view of the vicinity of the magnetic pole portion in embodiment 2.

Fig. 19B is an explanatory diagram of an enlarged view of the vicinity of the bridge portion of fig. 19A and the definition of the shape and size.

Fig. 20 is an explanatory diagram of the relationship between the pole arc radius and the normalized magnet flux density distribution of the air gap.

Fig. 21 is an enlarged view of the vicinity of the magnetic pole portion in embodiment 3.

Fig. 22 is an enlarged view of the vicinity of the magnetic pole portion in embodiment 4.

Fig. 23A is an enlarged view of the vicinity of the magnetic pole portion in embodiment 5.

Fig. 23B is an explanatory diagram of an enlarged view of the vicinity of the bridge portion of fig. 23A and the definition of the shape and size.

Detailed Description

Embodiments are described in detail as appropriate with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals, and description thereof is omitted.

(embodiment mode 1)

A structure of a permanent magnet type rotating electrical machine 1 having a rotor core according to embodiment 1 of the present invention will be described with reference to fig. 1 to 4. Fig. 1 is a cross-sectional view in a rotation plane of a permanent magnet type rotating electrical machine 1 according to embodiment 1. Fig. 2 is a perspective view of the stator core portion of fig. 1. Fig. 3 is a sectional view of the rotor 20 of embodiment 1. Fig. 4 is an enlarged view of the vicinity of the magnetic pole in the cross section of the permanent magnet type rotating electric machine 1 according to embodiment 1, and is an enlarged view of the X portion surrounded by the broken line in fig. 1.

As shown in fig. 1, a permanent magnet electric motor 1 according to the present embodiment is a 10-pole 60-slot distributed winding permanent magnet electric motor, and has a substantially annular stator 10 disposed on the outer circumferential side thereof and a substantially columnar rotor 20 disposed on the inner circumferential side thereof. An air gap 30 is provided between the stator 10 and the rotor 20. The stator 10 includes a stator core 100, a core back 110, teeth 130, and a plurality of windings 140, and is disposed opposite to the rotor 20 with an air gap 30 therebetween.

Fig. 2 shows a winding structure arranged on the stator core 100 of the permanent magnet type rotating electrical machine 1 illustrated in fig. 1. As shown in the drawing, the segment coil is constituted by a wave winding, and the opposite side of the insertion side of the segment coil is electrically connected by a connection portion 145 so that the wave winding can be electrically constituted. Solder, Tig soldering and laser welding are used as the connection means.

Four conductors are provided in one slot, and the first system winding 141 is constituted by two conductors on the inner peripheral side of the stator core. The second system winding 142 is formed of the remaining two windings on the outer peripheral side of the first system winding 141. The above-described dual system winding has a structure in which an insulating member 11 is provided between the systems to avoid mechanical or electrical contact. Therefore, the lead lines of the windings of the respective systems include a first system winding lead line 147 led from the inner peripheral side and a second system winding lead line 148 led from the outer peripheral side.

In the present embodiment, the dual system winding is designed to be taken out from the left and right opposite sides to avoid mechanical contact. In addition, each system winding is constituted by a three-phase winding. The crossover 143 is connected to the in-phase winding. Both the winding start line and the winding end line are drawn out to the control circuit side, and when the three-phase motor is configured, all the three-phase lines that have been wound are electrically connected by a relay.

Returning to fig. 1, the stator 10 is formed, for example, as follows. First, a plurality of radial teeth 130 are formed on the inner peripheral side of a stator core laminate obtained by laminating a whole press core of electromagnetic steel plates. Then, after the windings are provided on the respective teeth portions 130 to form the windings 140, integration is performed by shrink-fitting or press-fitting into a not-illustrated housing. The stator 10 is formed in this manner.

As shown in fig. 3, the rotor 20 of the present embodiment includes a rotor core 200, which is a core obtained by laminating electromagnetic steel sheets, and a shaft 300, which is a rotating shaft. The rotor core 200 has, for example, a symmetrical shape with respect to the magnetic pole center line, and the outer peripheral profile is a perfect circle. A 10-pole magnetic pole portion 220 is provided on the outer periphery of the rotor core 200 in the circumferential direction. The magnetic pole portion 220 has an arc-shaped outer peripheral end (magnetic pole arc) 219. Each magnetic pole portion 220 has one magnet insertion hole 201, the magnet insertion hole 201 being longer in the circumferential direction than in the radial direction, and has magnet stopper portions 211 on the inner peripheral sides of both ends of the magnet insertion hole 201.

In the magnet insertion hole 201, there is a rectangular-shaped magnet housing portion (space) 212 between the magnet stopper portions 211. The permanent magnet 210 is disposed in the magnet housing 212. In the example of fig. 3, the magnet housing 212 includes a region occupied by the permanent magnet 210, a gap between the outer peripheral side and the inner peripheral side of the permanent magnet 210, and a gap between the permanent magnet 210 and the gap 213.

As shown in fig. 4, the rotor 20 of the present embodiment has a gap 213 on the outer circumferential side of the magnet stopper 211, and a bridge 242 on the outer circumferential side of the gap 213. The gap 213 is a part of the magnet insertion hole 201. The rotor 20 has an umbrella-shaped core 230 on the outer peripheral side of the magnet housing portion 212, and has a connection portion 1(244) between the umbrella-shaped core 230 and the bridge portion 242.

Further, the rotor 20 has a q-axis core 221 between the adjacent magnet insertion holes 201. The rotor core outer circumferential portion 250 sandwiched between two imaginary q-axis direction straight lines VL1 and VL2 passing through both ends of the q-axis core 221 in the q-axis vertical direction minimum width (hereinafter referred to as Wq) is located on a circle having a radius substantially coincident with the rotor radius with the rotation axis as the center. Specifically, the rotor core outer circumferential portion 250 may be positioned on or near the circle of the rotor radius, may be spaced from the rotor radius by about several tens of μm, and may have a groove or a protrusion having a radial length of about several tens of μm. There is a connecting portion 2(243) between the q-axis core 221 and the bridge portion 242. The width Wq will be described later with reference to fig. 12A.

Further, the outer peripheral contours of the core of the umbrella-shaped core 230, the connecting portions 1(244), and the bridge portions 242 are formed in circular arcs, and the radial width (hereinafter referred to as Wb) of the bridge portions 242 is smaller than the radial length (hereinafter referred to as Tmg)/2 (for example, the thickness of the electromagnetic steel plate forming the laminated core is not more than) of the magnet housing portions 212 (or the magnet insertion holes 201). The width Wb and the length Tmg will be described later with reference to fig. 12A. Here, the outer peripheral contours of the core body of the umbrella-shaped core body 230, the connecting portions 1(244), and the bridge portions 242 are circular arcs, but may have a shape that does not degrade the torque ripple 12-order component in the magnetic pole center portion, for example, a convex portion having a radial length of about several tens μm. It is sometimes effective to provide a small groove in the center of the magnetic pole (described later in example 5).

Next, the arrangement of each coil in each slot of the stator 10 will be described with reference to fig. 5. In fig. 5, the upper case letters and the lower case letters of U, V, W indicate the opposite direction of current flow. In the case of fig. 5, 1U11 and 1U13 as coils of the first system are arranged on the inner diameter side of slot number 1. Further, the remaining 1U12 and 1U14 coils were arranged in slot No. 2. The coils are electrically connected in series. Further, the second system winding on the outer diameter side is provided with 2U11 and 2U13 coils in slot No. 2, and the remaining 2U12 and 2U14 coils in slot No. 3. The coils are electrically connected in series.

Since the second system winding is offset by one slot with respect to the first system winding, an electrical phase difference of 30 ° can be set as a result. This is because in the case of a 10 pole 60 slot, an offset of one slot is 1/12 for one pole pair, indicating an offset of 30 electrical degrees. Assuming that the first system winding and the second system winding are in phase, the phase of the magnetic field of the first system winding driving magnet poles and the phase of the magnetic field of the second system winding driving magnet poles are offset by 30 °, so that a difference is generated between respective torques and pulsations.

The embedded permanent magnet type rotary electric machine 1 of the present embodiment has a first system winding 141 connected to a first drive circuit including one or more three-phase inverters and a second system winding 142 connected to a second drive circuit including one or more three-phase inverters. Fig. 6 shows an example in which one three-phase inverter is connected to one system winding, and fig. 7A shows an example in which three-phase inverters are connected to one system winding.

Fig. 6 shows an example of a block circuit diagram for driving a dual system winding. The structure is explained. The drive circuit 1(40) and the drive circuit 2(41) are connected to a first system winding 141 composed of three-phase windings and a second system winding 142 having a phase difference of 30 ° in electrical angle from the first system winding 141, respectively.

The drive circuit includes an inverter circuit and a control ECU. Further, the drive circuits have phase current detection units CtU1 to CtW2, respectively, so that the currents of the respective phases can be fed back, and the imbalance between the two systems is corrected by measuring the current actually flowing with respect to the current command. So that the current phase of the second system winding can be adjusted.

Separate batteries Bat1 and Bat2 are connected to the

respective drive circuits

40, 41, and the generator 42 for charging the batteries Bat1 and Bat2 also has separate system terminals. This enables power to be supplied to the

drive circuits

40 and 41 independently of each other.

In fig. 6, the generator 42 is illustrated as a structure in which independent generating voltages are supplied from one housing, but generating voltages may be supplied from two generators, respectively, to completely separate the two systems. Further, the drive circuits 1(40) and 2(41) have the communication means 43 so that the conditions of each other can be grasped and the operation can be performed when an abnormality occurs to assist the portion where the motor drive on the failure side is lowered.

Fig. 7A shows a circuit configuration in which a unit capable of increasing the motor output is built in the two-system

motor drive circuits

40 and 41 shown in fig. 6. The difference from the configuration example shown in fig. 6 is that the batteries are unified from battery independent to battery unified, and the power generation command voltage Vref is output from the drive circuit 1(40) to the power generator 42. The drive circuit 1(40) includes an ECU1(81) and Inverters (INV)1(61), INV2(62) and INV3 (63). The ECU1(81), INV1(61), INV2(62), and INV3(63) are connected by

wires

71, 72, and 73, respectively. The drive circuit 2(41) includes an ECU2(82) and INV1(64), INV2(65), and INV3 (66). The ECU2(82) and INV1(64), INV2(65), and INV3(66) are connected by the

wirings

74, 75, and 76, respectively. The communication unit 43 is disposed between the drive circuit 1(40) (ECU1(81)) and the drive circuit 2(41) (ECU2(82)) so that the states of each other can be exchanged.

Fig. 7B shows a concept of coil arrangement when the system windings are four systems. This is an example in which one system winding is formed in a section halfway, and the remaining coils form the next system, rather than forming one system winding in the entire circumference. Fig. 7B shows that the first system winding 15 is formed of half of the entire circumference, and the second system winding 16 is formed of the remaining half. The third system winding 17 and the fourth system winding 18 arranged on the outer periphery thereof are formed by offsetting the switching portions of the systems by a mechanical angle of 90 °. By offsetting the switching portions of the first system winding 15, the second system winding 16, the third system winding 17, and the fourth system winding 18, there is an effect that the torque imbalance generated in the first system winding 15 and the second system winding 16 and the torque imbalance generated in the third system winding 17 and the fourth system winding 18 can be alleviated.

The motor having the four system windings shown in fig. 7B is driven by four systems by using four inverters by connecting the first inverter to the first system winding 15, connecting the first inverter to the second system winding 16, connecting the first inverter to the third system winding 17, and connecting the first inverter to the fourth system winding 18. When an abnormality occurs in a drive circuit connected to one system winding such as the second system winding 16, the remaining three systems operate, but by arranging the first system winding 15 to overlap with the third system winding 17 and the fourth system winding 18, the torque imbalance between the third system winding 17 and the fourth system winding 18 can be alleviated.

Here, in the rotating electrical machine in the case of using only the magnet torque, the torque ripple is reduced by making the magnet magnetic field and the winding magnetic field in the air gap close to a sine wave shape. In particular, with the rotor, the distance between the outer periphery of the magnetic pole and the stator becomes farther as the magnetic pole end portions are approached from the magnetic pole center, and the distance between the q-axis core and the stator is made particularly large, so that the magnet magnetic field approaches a sinusoidal wave shape, and the magnetic flux contributing to reluctance torque hardly passes through the rotor core. Since the stator has the same structure as the surface magnet type, a magnetic field from the stator generated when a sine wave current is applied to the winding becomes a sine wave shape in the air gap.

In contrast, the case of using the reluctance torque will be described with reference to fig. 8. In fig. 8, rotor core outer circumferential portion 250 sandwiched between two imaginary q-axis direction straight lines VL1 and VL2 is close to stator 10, and magnetic flux MF1 generating reluctance torque passes through rotor core 200 from stator 10, thereby generating reluctance torque. Further, reluctance torque is generated by causing rotor core magnetic pole portions 220 to approach a cylindrical shape and passing magnetic flux MF2 that generates reluctance torque from stator 10 through rotor core magnetic pole portions 220.

At this time, since the magnet magnetic flux MF3 also easily passes through the stator 10 side, the torque is increased more than the case of using only the magnet torque. On the other hand, the torque ripple is influenced by both the ripple of the magnet torque and the ripple of the reluctance torque, and therefore the torque ripple is further increased as compared with the case where only the magnet torque is used.

The inventors have found that torque ripple can be reduced by using reluctance torque. The structure and principle thereof will be explained below. The torque ripple studied here is the presence of a 6 th order component of 6 wavelengths and a 12 th order component of 12 wavelengths within the central angle range of the pole pair. First, the reduction of the torque ripple order 6 component will be described.

Fig. 9 shows torque waveforms T1 and T2 generated when the motor having the windings as shown in fig. 5 is operated at a current phase angle at which the maximum torque can be generated in each of the two systems, and a waveform of a resultant torque Tout obtained by superimposing the torques generated in the respective systems. The phase of the magnetic field of the magnet poles driven by the first system winding is identical to the phase of the magnetic field of the magnet poles driven by the second system winding. Further, the torque ripple generated in the first system winding and the magnet poles and the 6 th order component of the torque ripple generated in the magnet poles adjacent to the second system winding are opposite in sign.

The torque T2 generated by the second system winding can cancel the torque ripple repeated at a cycle of 60 ° in electrical angle with respect to the torque T1 generated by the first system winding, and the waveform of the resultant torque Tout can be a waveform with less torque ripple. Therefore, the motor for electric power steering exhibits excellent performance.

Since the cancellation of the 6 th order component is determined only by the rotational position of the rotor with respect to the system windings and the phase of each system winding, it is considered that not only the magnet torque but also the reluctance torque is established. Therefore, it is considered that the torque ripple 6 order component can be sufficiently reduced by the phase difference energization of the two system windings. The reduction of the torque ripple 6-order component by the configuration of the present embodiment will be described with reference to a graph of the calculation result of the torque ripple 6-order component obtained by the magnetic field analysis shown in fig. 10.

The graph shown in fig. 10 shows the total current of the two systems at 115A, with the phase angle of the current on the horizontal axis and the torque ripple component of order 6 on the vertical axis. Since the counter electromotive voltage is reduced by suppressing the magnetic flux of the magnet until the current phase angle used when the rotor rotates at high speed reaches about 85 degrees, the torque ripple is preferably small even at a large phase angle.

In fig. 10, the case where the phase difference is set to 30 ° in electrical angle between the systems and the case of the short-pitch winding having no phase difference are compared. As a result, when the inter-system phase difference is 30 °, the torque ripple 6 order component is substantially 1% or less at a current phase angle of 85 ° or less, and when there is no inter-system phase difference, the torque ripple 6 order component is particularly large when the current phase angle is large. It is thus understood that setting a phase difference between the systems has a great effect of reducing the torque ripple 6 th order component.

Other winding configurations are set forth herein. The number of poles of the permanent magnet type rotating electrical machine 1 is, for example, any of 8 poles, 10 poles, 12 poles, and 14 poles, and the rotor core 200 has a shape symmetrical with respect to the center line of the magnetic poles. Therefore, favorable characteristics are exhibited in the bidirectional rotary electric machine. For example, the number of poles and the number of slots of the permanent magnet type rotating electric machine 1 are 8-pole 48 slots, 10-pole 60 slots, 12-pole 72 slots, or 14-pole 84 slots. In the combination of the number of poles and the number of slots of these distributed windings, 6-order and 12-order torque ripples are generated for the pole pairs, and therefore the torque ripples can be reduced by the same configuration.

In fig. 5, when the in-phase coils of the adjacent slots are different systems by eliminating the slot offset of the inner and outer in-phase coils, the system in the case of no phase difference is the same as that of the 1 full-pitch winding, and therefore the torque ripple is larger than that of the short-pitch winding. In this case, when the optimal inter-system phase difference with the minimum torque ripple is 30 °, the torque ripple 6-order component can be reduced as in the above configuration example.

However, in this configuration example, when the inter-system phase difference deviates from the optimum phase difference angle, the torque ripple is more likely to increase than in the winding configuration of fig. 5. This is because the non-phase difference is a full-pitch winding, and the torque ripple is larger than the non-phase difference short-pitch winding of fig. 5. In order to control the torque ripple 6 order component to about 1%, the range of 4/5(24 °) to 6/5(36 °) of the optimum inter-system phase difference (30 °) is an allowable range of the phase difference. On the other hand, when the coils of the same phase in the adjacent slots are of different systems, the range of 9/10 to 11/10, which is the optimum inter-system phase difference, is the allowable range of phase difference.

In the configuration example of fig. 5, there are 2 in-phase coil slots within the range of the slots facing the magnet poles, but if the optimum phase angle difference is 2 times when the internal and external systems are separated when there are only 1 in-phase coil slot, the torque ripple can be reduced, but the torque is reduced.

In the case of concentrated winding, the two-system set phase difference may be effective or ineffective. For example, when there is a U-phase coil when viewed in the rotational direction and the mechanical angle difference from the next U-phase coil is not an integral multiple of 180 ° in electrical view, the phases of the magnetic poles of the winding magnetic flux drive magnets can be made uniform by setting the phase difference, and therefore the inter-system phase difference can be utilized. However, in the 8-pole 12-slot type 2: in the case of 3 series, or 4: in the case of 3-series, there is a U-phase coil when viewed in the rotational direction, and the mechanical angle difference from the next U-phase coil is 360 ° in electrical view, and therefore, the inter-system phase difference cannot be used. On the other hand, in the case of the 10-pole 12 slot or the 14-pole 18 slot, the torque ripple 6-order component can be reduced by the inter-system phase difference.

As a result, when torque ripple is reduced by reluctance torque, a stator capable of reducing the 6 th order component by phase difference energization of the two systems can be used. Therefore, the rotating electric machine of the stator capable of reducing the above-described torque ripple 6-order component and the rotor core structure capable of reducing the 12-order component can reduce the torque ripple by more appropriately utilizing the reluctance torque. The reduction of the torque ripple 12 order component will be described below. The rotor core structure capable of reducing the 12 th order component can be applied to a rotating electrical machine having a stator having a structure different from that of the stator capable of reducing the 6 th order component.

As a result of the study, it was found that (1) the radial thickness Hc of the umbrella-shaped core 230 is in the range of 0.5 to 1.0 times the length Hcm from the outer periphery of the umbrella-shaped core to the virtual chord of the developed pole pitch angle (2 pi/pole number) in the rotor core shape of the permanent magnet embedded rotating electrical machine 1 described in fig. 3 and 4; (2) an angle (central angle) of Wq as viewed from the rotation center of the rotor 20 is in a range of 0.4 to 0.9 times pi × rotor radius/(3 × pole number); (3) when Wq is within a range of 1.15 to 2.5 times of Hc, 12 th order component of torque ripple can be reduced while utilizing reluctance torque. The thickness Hc and the length Hcm are described later with reference to fig. 12A.

The rotor shape of the present embodiment will be described as a shape in which the 12 th order component of the reluctance torque ripple and the magnet torque ripple is cancelled out in order to reduce the 12 th order component of the torque ripple. At this time, the 12 th order components of the reluctance torque ripple and the magnet torque ripple are opposite in phase and equal in amplitude. The above-described shape condition range is shown in fig. 11, in which Hc is the horizontal axis and Wq is the vertical axis.

The shaded hexagonal areas in fig. 11 represent the shape ranges of the present embodiment. The shape range is sandwiched between 0.5 and 1.0 of straight lines Hc/Hcm perpendicular to the Hc axis, and between 0.4 of the center angle of the estimated straight line Wq perpendicular to the Wq axis and 0.9 of the center angle of the estimated straight line Wq. The straight line Wq/Hc is 1.15 and the straight line Wq/Hc is 2.5.

Further, fig. 12A and 12B show definitions of the dimensions of respective portions of the rotor core shape of fig. 4. Fig. 12B is an enlarged view of the vicinity of the bridge portion 242 of fig. 12A. In fig. 12A, Rt is a rotor radius and Rmg is a magnetic pole arc radius. The pole arc radius Rmg is a radius of curvature of the pole arc 219. Wb is the bridge width, e.g., substantially constant. Wmg is the circumferential length of the magnet housing portion 212, and Tmg is the radial length of the magnet housing portion 212 (magnet insertion hole 201).

Hc is the thickness of the umbrella-shaped core at the outer periphery of the magnetic pole. The umbrella core thickness Hc is the radial thickness of the pole center of the umbrella core 230. Hcm is the length of an imaginary chord from the outer periphery of the umbrella-shaped core to the developed pole pitch angle (2 pi/pole number). The length Hcm is the radial thickness of the imaginary arc when the center angle of the magnetic pole arc 219 is enlarged to the pole pitch end. Wq is the q-axis core width.

In fig. 12B, Rq is an arc radius (curvature radius) of the inner circumferential side of the connecting portion 2(243) connecting from the q-axis core 221 to the bridge 242, and Ls1 is a distance between the end of the outer circumference of the magnet housing portion 212 and the bridge 242. Lb is the length of the bridge 242. At this time, We (the distance between the end of the outer periphery of the magnet housing portion 212 and the q-axis core 221) and W1 (the umbrella thickness at the end of the outer periphery of the magnet housing portion 212) are automatically determined.

First, the phase of the torque ripple will be described with reference to fig. 13. As shown in fig. 13, the magnetic flux that generates reluctance torque flows along a path that passes from the q-axis core 221 of the rotor magnetic pole through the inner peripheral side of the magnet and flows to the adjacent q-axis core 221. Since reluctance torque is generated when stator 10 attracts rotor core 200, attraction force rises starting from the circumferential end of q-axis core 221, and pulsation also rises starting from the circumferential end of q-axis core 221. Therefore, since the rotation angle of the start position changes according to the q-axis core width, the pulsation phase changes.

On the other hand, since the magnetic flux that generates the magnet torque is a path that flows from the magnet magnetic pole to the adjacent magnet magnetic pole, and the two magnetic poles of the N pole and the S pole are integrated, the reference position of the node (peak) of the pulsation is at the center of the magnetic pole. At this time, even if the amplitude varies with the circumferential length of the magnet, the phase of the pulsation does not change.

Further, if the magnet torque ripple is considered to be a combined ripple of a ripple generated forward and a reverse ripple generated backward in the magnet rotation direction, as in the cogging torque, the phase of the combined ripple is not changed. When the phases of the front pulsation and the rear pulsation are shifted by the circumferential width of the magnet, the amplitude of the combined pulsation changes without changing the phase. The same phenomenon occurs when the circumferential extent of the magnet flux density distribution of the air gap is changed.

When the number of poles of the rotor 20 is set to P, when the range of the magnet magnetic flux density distribution of the air gap is expanded to a state larger than 4 pi/3P in a state where the central angle is smaller than 4 pi/3P, the vibration of the synthetic pulsation becomes small and the vibration direction is reversed. Therefore, the range of the magnet magnetic flux density distribution of the air gap is preferably close to 4 π/3P in the central angle.

A shape in which the phase of the reluctance torque ripple is opposite to the phase of the 12 th order component of the magnet torque ripple will be described with reference to fig. 13 and 14. As described above, in fig. 13, the start position of the reluctance torque ripple may be set to the point Sr, and the start position of the magnet torque ripple may be set to the point Sm at the center angle of 2 pi/3P from the magnetic pole center. The central angle between the point Sr and the point Sm is pi/3P + pi/6P-1.5 pi/3P.

In addition, as shown in fig. 14, one cycle of the 12 th order component is pi/3P, and the start positions of the reluctance torque ripple and the magnet torque ripple are delayed by 1.5 cycles, so that the phases of the reluctance torque ripple and the magnet torque ripple are opposite. At this time, if the amplitudes of the 12 th order components of the reluctance torque ripple and the magnet torque ripple are the same, they are cancelled out, and the resultant ripple is reduced.

The dimensions at this time were: (1) the central angle of Wq is less than or equal to pi/3P, (2) the central angle of Wmg is less than or equal to 4 pi/3P, and (3) the central angle of We is less than or equal to pi/6P. Here, the center angle of Wq + the center angle of Wmg + the center angle of We × 2 ═ 2 pi/P.

The condition (1) is necessary in order to set the phase difference from the magnet torque ripple to 1.5 cycles. At this time, the rotation angle of the magnetic flux generating the reluctance torque from the rise to the end is pi/3P which is the same as the period of the 12 th order component, and the main body of the generated reluctance torque ripple is the 12 th order component. The upper limit of the central angle of Wq is smaller than pi/3P because the connecting portion 2(243) has a radial length larger than the bridge width and is connected to the bridge portion 242 in the circumferential direction. Considering that the center angle of the outer peripheral contour portion of the q-axis core at the same distance from the stator is effectively enlarged, the upper limit value of the center angle/(pi/3P) of the Wq is 0.9.

The condition (2) is necessary in order to make the range of the magnet magnetic flux density distribution of the air gap appropriate (about 4 π/3P). Further, since the magnet magnetic flux is circumferentially spread by the connecting portion 1(244), less than 4 π/3P is required.

As a result, for the condition (3), the center angle of We is larger than π/6P. Further, the connection portion 1(244), the bridge portion 242, and the connection portion 2 are included in the center corner of We. Further, if the center angle of We > π/6P, as long as Wb is small, leakage flux from a magnetic pole of a magnet to another magnetic pole of the same magnet can be reduced, thereby effectively maintaining a large magnet torque. In this case, Wb is preferably equal to or less than the thickness of the electromagnetic steel sheets laminated to form the rotor core. The center angle of the length Lb of the bridge portion 242 is preferably (pi/6 p) × 0.6 or more.

Since the above-described connecting portion 2 has a radial length larger than the bridge width and is connected to the bridge portion 242 in the circumferential direction, the lower limit of the central angle of Wq is smaller than pi/3P, and the lower limit of the central angle/(pi/3P) of Wq is 0.4 as a result of the study. However, if there is a recess on the q-axis core in the range of Wq, the 12 th order component of the reluctance torque ripple decreases while the high order component increases.

Here, whether or not there are other effective shape ranges is examined. Consider the case where the reluctance torque is applied to a large extent by increasing the central angle of Wq and decreasing the central angle of Wmg. In this case, for example, the central angle Wq is 2 pi/3P, Wmg and the central angle Wq is 3 pi/3P, the phase of the 12 th order component of the reluctance torque ripple is advanced by pi/3P/2 (half cycle), and the phase of the magnet torque ripple is not changed.

Further, when the central angle of Wq is 3 π/3P, the central angle of Wmg is 2 π/3P, since the magnet torque is small, the torque of the same size is reduced, which is not preferable. Thus, in order to reduce the torque ripple 12-order component, it is necessary to restrict the use of the reluctance torque to some extent.

The range of the central angle of Wq estimated as described above is explained below by examining the waveform of the reluctance torque and the waveform of the magnet torque by magnetic field analysis. The reluctance torque waveform can be calculated by storing the magnetic permeability distribution in the electromagnetic steel sheet at the time of calculating the torque as numerical data in advance, and calculating under the condition that there is no magnetic flux of the magnet but there is a current using the magnetic permeability distribution data. The magnet torque can be calculated by subtracting the reluctance torque from the torque. Therefore, it is explained that the phases of the pulsation waveforms of the reluctance torque and the magnet torque are opposite in the rotor shape of the present invention.

Fig. 15 shows ripple waveforms having a current phase angle of 30 ° when Hc/Hcm is 0.694, and when Wq has a center angle/(pi/3P) of 0.432, 0.577, and 0.721 (the center angle of Wq in a 10-pole 60 slot is 2.59 °, 3.46 °, and 4.32 °). In addition, the position of the calculated shape within the shape range is shown in the shape range diagram. The ripple waveform of fig. 15 is calculated by subtracting the average torque from the torque waveform.

As shown in fig. 15, when Wq has a center angle/(pi/3P) of 0.577, the phases of the magnet torque ripple and the reluctance torque ripple are opposite to each other, the amplitudes are close to each other, and the resultant ripple is small. On the other hand, when the central angle/(π/3P) of Wq is 0.432, the phase of the reluctance torque ripple is retarded, and the resultant ripple is large. When the central angle/(pi/3P) of Wq is 0.721, the phase of the reluctance torque ripple is advanced, and the resultant ripple is large. The phase of the magnet torque ripple also changes, but the fluctuation does not increase even when Wq and Wmg change greatly, and is substantially constant with respect to the shape change. From this, it was confirmed by magnetic field analysis that Wq has an influence on the phase of the reluctance torque ripple.

If the shape of the torque ripple is less than 2% by magnetic field analysis, the central angle/(pi/3P) of 0.5. ltoreq. Wq is 0.75. If shapes with torque ripple less than 4% are searched, the central angle/(π/3P) of 0.4 ≦ Wq is ≦ 0.9, and the range increases proportionally. Therefore, when the torque ripple is improved from 5% to less than 4% in the conventional art, the center angle/(π/3P) of 0.4. ltoreq. Wq is in a shape range of 0.9, but the center angle/(π/3P) of 0.5. ltoreq. Wq is more preferably in a shape range of 0.75.

Next, the rotor core shape of the present embodiment is described such that the amplitudes of the 12 th order components of the reluctance torque ripple and the magnet torque ripple are close to each other, and the reluctance torque ripple and the magnet torque ripple are cancelled out, thereby sufficiently reducing the 12 th order component of the torque ripple. The torque ripple 12-order component has the same order as the 12-order component of the lowest order of the cogging torque determined by the number of poles and the number of slots.

When the gap magnet magnetic flux density distribution is in the range of about 4 pi/3P, the 12 th order component of cogging torque can be reduced. In addition, when the gap magnet magnetic flux density distribution range is about 4 pi/3P, the magnet torque ripple 12-order component of the same order also tends to decrease. Therefore, when the central angle of Wmg is ≦ 4 π/3P, the central angle of Wmg needs to be close to 4 π/3P. However, in order to cancel the reluctance torque ripple and the magnet torque ripple, the reluctance torque ripple 12 order component cannot be too small.

Here, the influence of the radial length Hc of the umbrella core 230 on the magnetic flux density distribution of the air gap will be described with reference to fig. 16. The magnet flux density distribution of the air gap is calculated by magnetic field analysis. Fig. 16 shows a distribution normalized by dividing the magnet flux density distribution of the air gap by the magnet flux density distribution value at the magnetic pole center when Hc is changed in the rotor core shape of the present embodiment. In fig. 16, it is shown that the distribution range becomes large as Hc increases. The reason for this is considered to be that the magnet magnetic flux is easily moved due to the enlargement of the umbrella-shaped core region.

When the center angle of the half-value width of the normalized magnet magnetic flux density distribution changes from a value smaller than 4 pi/3P to a value larger than 4 pi/3P, the 12 th order component changes in a direction in which the amplitude decreases and the vibration is inverted in positive and negative directions, and progresses in phase with the reluctance torque ripple. At this time, in order to achieve cancellation by having a phase opposite to that of the reluctance torque ripple, the 12 th order component needs to be in a range where the positive and negative of the vibration are not inverted. At this time, it is necessary that the center angle of Wmg be 4 π/3P or less and Hc be < Hcm.

Fig. 17 shows ripple waveforms having a current phase angle of 30 ° obtained by magnetic field analysis when Hc/Hcm is set to 0.617, 0.694, and 0.771 in a 10-pole 60-slot motor, and when the center angle/(pi/3P) of Wq is 0.577. The ripple waveform is calculated by subtracting the average torque from the torque waveform. In addition, the positions of the calculated shapes within the shape range are shown in the shape range diagram.

As shown in fig. 17, when Hc/Hcm is 0.771, the magnet torque ripple is small, the reluctance torque ripple is large, the phase is reversed, and the resultant ripple is large. When Hc/Hcm is 0.617, the magnet torque ripple is large, the reluctance torque ripple is small, the phase is opposite, and the resultant ripple is large. On the other hand, when Hc/Hcm is 0.694, the phases of the magnet torque ripple and the reluctance torque ripple are opposite to each other, the amplitudes thereof are close to each other, and the resultant ripple is small.

Here, the magnet torque ripple varies with Hc/Hcm because the range of the normalized magnet flux density distribution of the air gap varies with Hc/Hcm as described above. In the range where the positive and negative of the oscillation of the pulsation 12 order component are not inverted, the reluctance torque pulsation and the 12 order component have opposite phases and close amplitudes, and Hc/Hcm is 0.694.

Here, Hc increases and the magnet torque ripple decreases because the range of the normalized magnet flux density distribution of the air gap increases, and therefore the phases of the ripple generated forward in the rotation direction of the magnet and the ripple generated rearward in the rotation direction of the magnet approach opposite phases, and the magnet torque ripple resulting in the ripple decreases. When the circumferential range of the magnet magnetic flux distribution is increased, the amplitude of the composite pulsation changes because the phases of the front and rear pulsations are advanced or retarded.

On the other hand, as shown in fig. 17, the core region increases with an increase in Hc, but the increase in reluctance torque ripple is small. This indicates that the range of Hc in the present embodiment has a small influence on the reluctance torque ripple. Through magnetic field analysis, if the shape of the 12 th order component of the torque ripple is less than 2%, Hc/Hcm is more than or equal to 0.55 and less than or equal to 0.9. If the shape with the 12 th order component of the torque ripple less than 4% is searched, Hc/Hcm is more than or equal to 0.5 and less than or equal to 1.0, and the range less than 4% is increased by 0.15 relative to the range less than 2% of 0.35. Therefore, when the torque ripple is improved by less than 4% as compared with the conventional torque ripple, the shape range is 0.5 Hc/Hcm < 1.0, and more preferably 0.55 Hc/Hcm < 0.9.

Further, as a result of the study of the analysis results, the inventors found that Wq and Hc associated with the reduction of the torque ripple 12 order component are not independent, and that Wq/Hc also has a suitable shape range of the reduction of the torque ripple 12 order component. Through magnetic field analysis, if the shape of the 12 th order component of the torque ripple is less than 2%, the Wq/Hc is more than or equal to 1.2 and less than or equal to 2.1. If the shape with the 12 th order component of the torque ripple less than 4% is searched, the Wq/Hc is more than or equal to 1.15 and less than or equal to 2.5, and the range less than 4% is increased by 0.4 relative to the range less than 2% of 0.95. Therefore, when the torque ripple is improved to less than 4% as compared with the conventional torque ripple, the shape range is 1.15. ltoreq. Wq/Hc.ltoreq.2.5, and more preferably 1.2. ltoreq. Wq/Hc.ltoreq.2.1.

Further, it is also conceivable to maintain the range of the normalized magnetic flux density distribution by increasing Hc and decreasing Wmg, but since the torque decreases when decreasing Wmg, Wmg is not desired to be excessively small. At this time, the central angle/(4 π/3P) of Wmg is preferably between 7/8 and 1.

Here, whether Hc and Wq are appropriate or not will be described with respect to the shape range different from that of the present embodiment. It is also considered to increase Hc to invert the positive and negative oscillations of the magnet torque ripple 12 order component, increase the central angle of Wq, decrease the central angle of Wmg, invert the positive and negative oscillations of the reluctance torque ripple 12 order component, and invert the phases of the magnet torque ripple 12 order component and the reluctance torque ripple 12 order component. However, since Wmg becomes smaller, the torque decreases, and the cogging torque is difficult to decrease.

Here, the influence of the connection portions 1(244) and 2(243) on both sides of the bridge portion 242 will be described. When the connection portion 1(244) becomes large, the gap magnetic flux density increases at the end of the umbrella core 230, and the shoulder of the normalized magnetic flux density distribution increases. However, when the umbrella thickness is thin and the radial thickness of the connecting portion 1(244) is close to the bridge width, the influence on the 12 th order component of the torque ripple is small and only the cogging torque is affected. When the umbrella thickness is large, if the current phase angle is large and the magnet magnetic flux is suppressed, the normalized magnetic flux density distribution tends to increase if the connection portion 1(244) is large, and thus the torque ripple 12-order component tends to increase. Therefore, it is preferable to reduce the range of the connection portion 1(244) when the umbrella is thick.

In this case, in the connecting portions 1(244) that affect the 12 th order components of the cogging torque and the torque ripple, when the umbrella thickness is large, the central angle of the inner circumferential ends of the two connecting portions 1(244) before and after in the rotation direction is preferably close to 4 pi/3P. Further, the size of the connection portion 2(243) affects the phase of the reluctance torque ripple. From the viewpoint of utilizing reluctance torque, it is preferable that the radius of the arc connecting from the q-axis core of the gap 213 to the bridge portion 242 be reduced and Wq be increased.

From the above studies, it was confirmed that the following configuration is effective for reducing the 12 th order component of the torque ripple. The rotor core outer peripheral portion 250 sandwiched between two imaginary q-axis direction straight lines passing through both ends of the q-axis perpendicular direction minimum width Wq of the q-axis core 221 is located on a circle having a radius substantially identical to the rotor radius with the rotation axis as the center, and the core outer peripheral contour of the umbrella core 230, the connection portions 1(244), and the bridge portions 242 is formed by an arc. The outer peripheral contour of the rotor may be a perfect circle, and it is preferable that the width Wb of the bridge portion 242 is small, is smaller than 1/2 (for example, equal to or less than the thickness of an electromagnetic steel plate) of the radial length Tmg of the magnet housing portion 212 (the magnet insertion hole 201), the center angle of Wmg is close to 4 pi/3P but smaller than 4 pi/3P, (1) Hc is in the range of 0.5 to 1.0 times Hcm, (2) Wq is in the range of pi × 0.4 to 0.9 times rotor radius/(3 × the number of poles), (3) Wq is in the range of 1.15 to 2.5 times Hc.

According to the above configuration, the q-axis core width and the umbrella-shaped core thickness capable of canceling the 12 th order component of the reluctance torque ripple and the magnet torque ripple by the reluctance torque are provided, and the 12 th order component of the torque ripple can be reduced.

The conventional rotor core shape may have a feature that the radial length of the umbrella core 230 is long, the q-axis core width is wide, or the width of a portion corresponding to the bridge 242 is wide. This is because, in order to use the reluctance torque largely, the core region through which the magnetic flux contributing to the reluctance torque passes is enlarged, and the torque ripple cannot be sufficiently reduced. Further, the structure other than the above-described conventional structure has a feature that the q-axis core width is considerably narrow or a recessed portion is formed in the q-axis. This structure mainly focuses on the magnetic flux contributing to the magnet torque, and narrows the q-axis core region through which the magnetic flux generating reluctance torque passes, without using the q-axis reluctance torque.

The rotor core shape capable of reducing the torque ripple 12 order component of the present embodiment is different from the conventional rotor core shape in that it has a q-axis core width and an umbrella-shaped core thickness capable of reducing the torque ripple 12 order component by the reluctance torque.

The structure of the permanent magnet type rotating electrical machine 1 according to the present embodiment described with reference to fig. 1, 2, and 4 is determined based on the above-described results of the study. That is, the rotor 20 has the gap 213 on the outer peripheral side of the magnet stopper 211, and the bridge 242 on the outer peripheral side of the gap 213. Further, the umbrella core 230 is provided on the outer peripheral side of the magnet housing portion, and the connection portion 1(244) is provided between the umbrella core 230 and the bridge portion 242.

Further, a q-axis core 221 is provided between adjacent magnet insertion holes 201, a rotor core outer peripheral portion 250 sandwiched between two imaginary q-axis direction straight lines passing through both ends of a minimum width Wq in the q-axis vertical direction of the q-axis core 221 is positioned on a circle having a radius substantially coincident with a rotor radius with the rotation axis as a center, and a connecting portion 2(243) is provided between the q-axis core 221 and the bridge portion 242.

Further, the outer peripheral contours of the core of the umbrella-shaped core 230, the connecting portions 1(244), and the bridge portions 242 are formed by arcs, and the radial width Wb of the bridge portions 242 is smaller than the radial length Tmg/2 of the magnet housing portion 212 (the magnet insertion hole 201) (for example, equal to or smaller than the thickness of the electromagnetic steel sheet forming the laminated core).

Further, the outer peripheral portion of the rotor core sandwiched between two imaginary straight lines in the q-axis direction passing through both ends of the minimum width Wq in the q-axis vertical direction of the q-axis core 221 is positioned on a circle having a radius substantially identical to the rotor radius with the rotation axis as the center, the umbrella-shaped core 230, the connecting portion 1(244), the outer peripheral contour of the core of the bridge 242 may be a perfect circle, the outer peripheral contour of the rotor may be a perfect circle, the width Wb of the bridge 242 is preferably small, smaller than 1/2 (for example, equal to or less than the thickness of the electromagnetic steel plate) of the radial length Tmg of the magnet housing 212 (the magnet insertion hole 201), the center angle of Wmg is close to 4 pi/3P and smaller than 4 pi/3P, (1) Hc is in the range of 0.5 to 1.0 times of Hcm, (2) Wq is in the range of 0.4 to 0.9 times of pi × the radius of the rotor/(3 × the number of poles), (3) Wq is in the range of 1.15 to 2.5 times of Hc.

The torque ripple of the permanent magnet type rotating electric machine 1 can be reduced by the rotor core having the magnetic pole portion shape described above. Further, according to the configuration in which the two system windings are energized with a current phase difference set, the permanent magnet type rotating electric machine 1 which is more excellent in reducing the torque ripple can be obtained.

Fig. 18 shows the results of calculating the characteristics of the permanent magnet type rotating electric machine 1 according to the present embodiment by magnetic field analysis. As shown in fig. 18, the torque ripple 6 order component is less than 1% when the phase angle of the current is 85 degrees or less. When the current phase angle is 60 ° or less, the torque ripple 12-order component is approximately 2% or less. Even if the phase angle of the current of torque reduction is 5% at 85 degrees, a small torque ripple 12-order component can be obtained even at a high phase angle. Therefore, the configuration of the present invention shows that a torque ripple larger and smaller than the conventional one can be realized.

Thus, the configuration of the present embodiment shows that a torque ripple larger and smaller than that of the conventional one can be realized. Further, it is also known that the use of reluctance torque can greatly increase the torque for the amount of magnet used.

By using the permanent magnet type rotating electrical machine 1 according to the present embodiment in the EPS device, vibration and noise transmitted in the vehicle compartment can be suppressed. Further, by applying the present invention to other electric auxiliary devices for an automobile, for example, an electric auxiliary device for an automobile that performs electric braking, vibration and noise can be suppressed. The application of the permanent magnet rotating electrical machine 1 according to the present embodiment is not limited to the automobile field, and can be applied to all industrial permanent magnet rotating electrical machines in which low vibration is desired.

Here, a case where the material of the rotor is changed will be described. As for the change in the material of the electromagnetic steel sheet, for example, the influence of working and stress, as long as the magnetic permeability is much higher than the magnetic permeability of the gap, the magnetic flux density distribution of the air gap does not change, and therefore the influence on the torque ripple is small, and the shape of the core becomes dominant. This is confirmed because the magnetic flux density distribution of the air gap and the torque ripple in the magnetic field calculation result were not affected even if the magnetic permeability on the outer peripheral side of the magnet insertion hole was 1/100.

Further, it was confirmed that when the magnet material was changed, the magnet flux density distribution and the torque ripple of the air gap in the magnetic field calculation result of the circular rotor were not affected even when the residual flux density was changed from 1.1T to 1.6T. The reason for this is considered to be that the air gap is uniform in the circumferential direction, and the magnetic resistance in the circumferential direction does not change, and therefore, the air gap is less susceptible to the influence of the residual magnetic flux density of the magnet. Thus, the influence of the change in the electromagnetic steel sheet material and the magnet material is small, and the influence of the core shape becomes dominant.

(embodiment mode 2)

Next, a permanent magnet type rotating electric machine 1 according to embodiment 2 will be described with reference to fig. 19A and 19B. Fig. 19A is an enlarged view of the vicinity of the magnetic pole in the cross section of the rotor 20 according to embodiment 2, and corresponds to fig. 4 described in embodiment 1. Fig. 19B is an explanatory diagram of an enlarged view of the vicinity of the bridge portion of fig. 19A and the definition of the shape and size. Note that portions common to embodiment 1 are not partially described.

In fig. 4, the magnetic pole arc radius Rmg matches the rotor radius Rt, but in the permanent magnet type rotating electric machine 1 according to the present embodiment, the difference is that Rmg is Rt × 0.68. At this time, the outer peripheries of the umbrella-shaped core 230, the connecting portions 1(244), and the bridge portions 242 form arcs having a radius Rmg.

The rotor core outer circumferential portion 250 sandwiched between two imaginary q-axis direction straight lines VL1, VL2 passing through both ends of the minimum width Wq in the q-axis vertical direction of the q-axis core 221 is located on a circle of a radius Rt around the rotation axis. When the magnetic pole arc radius Rmg is smaller than the rotor radius Rt, Hc increases because the bridge portion 242 is located on the inner circumferential side of the rotor outer radius, and Hcm also increases because the intersection point P in the radial direction of the magnetic pole arc and the pole pitch end is located on the inner circumferential side. The Hcm at this time is given by the following equation. Hcm ═ Rmg × (1-COS ((ASIN ((Rt-Rmg)/Rmg × SIN (pi/P)) + pi/P))).

Since the magnet housing portion 212 moves toward the inner peripheral side, the center angle of Wmg increases. The air gap increases as one approaches the bridge 242 from the center of the pole, reducing the air gap magnet flux density on the side closer to the bridge 242. At this time, what acts in the direction of increasing the range of the normalized magnet flux density distribution of the air gap is an increase in Hc and an increase in the estimated center angle of Wmg, and what acts in the decreasing direction is the air gap that increases with distance from the center of the magnetic pole.

Further, since the air gap is not fixed, when the residual magnetic density of the magnet becomes large, the gap magnetic flux density tends to increase relatively greatly in a portion away from the center of the magnetic pole in the circumferential direction, and the magnet material has an influence. Therefore, the increase in the magnet residual density acts in a direction to increase the range of the normalized magnet flux density distribution of the air gap.

As shown in fig. 20, when Rmg is Rt, the normalized distribution approaches a rectangular distribution, and the slope of the shoulder at the distribution end steeply inclines. As Rmg becomes smaller, the normalized distribution approaches a sine wave, and the slope of the shoulder at the distribution end becomes gentle. At this time, it is found that when the slope of the shoulder is gentle, an optimum distribution is obtained which gives a low torque ripple 12 th order component with a small half width.

As a result of the magnetic field analysis, the center angle of the range of the optimum distribution when Rmg — Rt is (4 pi/3P) × 1.0375, and the center angle of the range when Rmg — Rt × 0.68 is (4 pi/3P) × 0.971. The above optimum distribution is as follows: when Rmg is Rt, the central angle/(4 pi/3P) of 23/24 ≦ Wmg is ≦ 1, and when Rmg is Rt × 0.68, the central angle/(4 pi/3P) of 11/12 ≦ Wmg is ≦ 1. In addition, the distribution gives a smaller cogging torque.

Depending on the normalized distribution range, the optimum Hc/Hcm is 0.671 at Rmg ═ Rt and 0.576 at Rmg ═ Rt × 0.68. The difference in distribution range by Rmg produced a difference of 0.1 in Hc/Hcm. Therefore, when Rmg is small, Hc becomes relatively small. However, when Hc cannot be reduced due to manufacturing reasons or the like, the magnet magnetic flux density is reduced or Wmg is reduced in order to reduce the range to an appropriate distribution range. However, to avoid torque drop, it is preferable that Wmg not be too small. Therefore, the central angle/(4 π/3P) of Wmg is preferably 7/8 or more.

Further, it was confirmed by magnetic field analysis that the outer peripheral shape of the rotor core had an influence on the proper normalized distribution, but Wb had no influence on the proper normalized distribution. When Rmg is Rt × 0.68, the normalized distribution tends to expand in the circumferential direction when the residual magnetic flux density of the magnet is changed to increase. If the scale Wmg is reduced, the circumferential width of the normalized distribution can be controlled. As Rmg becomes smaller, the effect of increasing or decreasing the range of the normalized magnet magnetic flux density distribution of the air gap is multiplied by the range decreasing effect caused by the change in the distribution shape, but the effect of the change in the distribution shape is most influential. Therefore, Hc/Hcm tends to decrease as compared with Rmg ═ Rt.

Here, the thickness of the end of the umbrella-shaped core is preferably Wb or more for manufacturing reasons, and therefore, when Hc/Hcm is determined according to the lower limit of the thickness of the end of the core on the umbrella, Hc/Hcm tends to be larger than the appropriate one. Therefore, the range of the normalized magnet flux density distribution of the air gap becomes larger than the suitable distribution range, and Wmg is reduced in order to make the distribution range suitable. At this time, since the normalized magnet magnetic flux density distribution is mountain-shaped and is reduced Wmg, the torque is reduced, and it is not desirable that Rmg be excessively small. Therefore, the lower limit of Rmg is preferably Rt × 2/3 or more.

Here, the influence of the connection portion 2(243) on the q-axis side of the bridge portion 242 will be described. Although the rotor core outer circumferential portion 250 sandwiched between two imaginary q-axis direction straight lines passing through both ends of the minimum width (hereinafter referred to as Wq) in the q-axis vertical direction of the q-axis core 221 is located on a circle of the radius Rt centered on the rotation axis, a q-axis outer circumferential arc may be formed on the circle of the radius Rt over a larger range than the rotor core outer circumferential portion 250, which means that the connection portion 2(243) is increased.

The connecting portion 2(243) includes an end point of the q-axis outer circumferential arc to an outer circumferential connecting point connected to the bridge portion 242. The inner circumferential contour of the connecting portion 2(243) is formed by a circular arc, the q-axis core is connected to the bridge portion 242, and the connecting portion 2(243) includes the inner circumferential connecting point of the inner circumferential contour circular arc and the bridge portion 242. The outer circumferential connection point and the inner circumferential connection point are closer to the magnetic pole center side, indicating that the connection portion 2(243) is larger. Since the connection portion 2(243) becomes large, the phase of the reluctance torque ripple is changed and the order 12 component of the torque ripple is affected, so that the positions of the arc end point and the connection point are limited.

The end points of the q-axis outer circumferential arc are directly related to the start position of the reluctance torque ripple, and therefore the center angle of the q-axis outer circumferential arc needs not to reach pi/3P, and is preferably smaller than the average of pi/3P and the center angle of the rotor core outer circumference 250 sandwiched between two imaginary q-axis direction straight lines. On the other hand, the center angle of points on both sides of the q-axis of the estimated peripheral connection point may be larger than pi/3P. The inner circumferential connection point is preferably of the same degree as the estimated angle of the outer circumferential connection point.

When the characteristics of the permanent magnet type rotating electric machine 1 according to the present embodiment are calculated by magnetic field analysis, the torque ripple 12 order component is 0.5% at the current 115A and the current phase angle of 30 °. Therefore, it is found that the torque ripple is sufficiently reduced even when the magnetic pole circular arc radius is Rt × 0.68. The maximum torque is a value reduced by 4% as compared with the case of embodiment 1.

As a result of the above studies, the structure of embodiment 2 has an excellent effect of torque ripple.

In the present embodiment, as in embodiment 1, by using the permanent magnet type rotating electric machine 1 of the present embodiment in an EPS device, it is possible to suppress vibration and noise transmitted into the vehicle cabin. Further, by applying the present invention to other electric auxiliary devices for an automobile, for example, an electric auxiliary device for an automobile that performs electric braking, vibration and noise can be suppressed. The application of the permanent magnet rotating electrical machine 1 according to the present embodiment is not limited to the automobile field, and can be applied to all industrial permanent magnet rotating electrical machines in which low vibration is desired.

(embodiment mode 3)

Next, a permanent magnet type rotating electrical machine 1 according to embodiment 3 of the present invention will be described with reference to fig. 21. Fig. 21 is an enlarged view of the vicinity of the magnetic pole in the cross section of the rotor 20 according to embodiment 3, and corresponds to fig. 4 described in embodiment 1. Note that portions common to embodiment 1 are not partially described.

In the permanent magnet type rotating electrical machine 1 described in embodiment 1, the bridge width is formed to be smaller than the thickness of the electromagnetic steel sheet forming the laminated core, but the bridge width of the permanent magnet type rotating electrical machine 1 in the present embodiment is equal to the thickness of the electromagnetic steel sheet. When the bridge width is increased from 0.25 to 0.5mm, the range of gap flux distribution is reduced due to increased leakage. When the distribution range when the bridge width is increased is evaluated by magnetic field calculation, the distribution range substantially matches the distribution range when Hc is decreased by the same amount as Wb is increased without changing the bridge width. In addition, the preferred normalized distribution is the same distribution shape, independent of Wb. Therefore, when Wb differs between different rotors 20, if Hc' is used (change of Hc — reference Wb), the following shape range can be obtained in consideration of the influence of Wb. The reference Wb is Tb/2.

(1) 0.5. ltoreq. (Hc-Wb + Tb/2)/Hcm. ltoreq.0.8, and (2) 0.4. ltoreq. Wq/[ pi/(3P). times.rotor radius ]. ltoreq.0.9, and (3) 1.2. ltoreq. Wq/(Hc-Wb + Tb/2). ltoreq.2.5. However, in order to obtain good characteristics, it is more preferable that (1) 0.5. ltoreq. Hc-Wb + Tb/2)/Hcm. ltoreq.0.7, and (2) 0.5. ltoreq. Wq/[ pi/(3P). times.rotor radius ]. ltoreq.0.75, and (3) 1.25. ltoreq. Wq/(Hc-Wb + Tb/2). ltoreq.2.1.

When the characteristics of the permanent magnet type rotating electric machine 1 according to the present embodiment are calculated by magnetic field analysis, the torque ripple 12 order component is 0.2% at the current 115A and the current phase angle of 30 °. Therefore, even when the magnetic pole arc radius is Rt × 0.68 and the bridge width is equal to the thickness of the electromagnetic steel plate, the torque ripple can be sufficiently reduced. The maximum torque is a value that is 5% lower than that in embodiment 1.

(embodiment mode 4)

Next, a permanent magnet type rotating electrical machine 1 according to embodiment 4 of the present invention will be described with reference to fig. 22.

As shown in fig. 22, the magnetic pole portion 220 of the permanent magnet type rotating electrical machine 1 according to the present embodiment has the same configuration as that of embodiment 2. That is, the magnetic pole portion 220 has the same shape of the circular arc radius of the magnetic pole as shown in fig. 19A and 19B, except that the bridge width is made equal to the thickness of the electromagnetic steel plate. Note that portions common to embodiment 2 are not partially described.

When the characteristics of the permanent magnet type rotating electric machine 1 according to the present embodiment are calculated by magnetic field analysis, the torque ripple 12 order component is 0.4% at the current 115A and the current phase angle of 30 °. Therefore, it is found that the torque ripple can be sufficiently reduced even when the magnetic pole arc radius is Rt × 0.68 and the bridge width is equal to the thickness of the electromagnetic steel sheet. The maximum torque is a value reduced by 10% as compared with the case of embodiment 1.

(embodiment 5)

Next, a permanent magnet type rotating electrical machine 1 according to embodiment 5 of the present invention will be described with reference to fig. 23A and 23B. The permanent magnet type rotating electrical machine 1 according to the present embodiment is a 10-pole 60-slot concentrated winding rotating electrical machine as in embodiment 1. Fig. 23A is an enlarged view of the vicinity of the magnetic pole in the cross section of the rotor 20 according to embodiment 5, and corresponds to fig. 4 described in embodiment 1. Fig. 23B is an enlarged view of the vicinity of the bridge portion 242 of the rotor 20 according to embodiment 5. Note that portions common to embodiment 1 are not described. Ls2 is the distance between the circumferential end of the outer periphery side of the magnet housing portion 212 and the circumferential end of the inner periphery side linear portion of the umbrella core 230.

On the arc of the outer peripheral contour of the core, a groove 400 having a shallow and small width may be provided at the magnetic pole center portion. In this case, in the gap magnetic flux distribution, the gap length at the magnetic pole center portion increases, and the magnetic flux goes around from the periphery to the center portion, and the circumferential width of the distribution becomes slightly narrower. Further, since the magnetic flux that passes through the umbrella core 230 and contributes to the reluctance torque is reduced, the magnet torque ripple and the reluctance torque ripple are not sufficiently cancelled out.

If the radial length of the umbrella core 230 is increased to eliminate these variations, the torque ripple 12 order component and the cogging torque 12 order component can be reduced. In this case, the same conditional expression can be used when the radial length of the umbrella core at the magnetic pole center portion is Hc. Further, since the thickness of the umbrella core 230 is increased, the thickness of the end of the umbrella core is also increased, and as described above, the connection portion 1(244) becomes large in the circumferential direction to deteriorate the torque ripple 12 order component. Therefore, the central angle of both sides of the magnetic pole at the inner peripheral end of the connecting portion 1(244) is set to a value close to 4 pi/3P.

When the characteristics of the permanent magnet type rotating electric machine 1 according to the present embodiment are calculated by magnetic field analysis, the torque ripple 12 order component is 2.1% at the current 115A and the current phase angle of 30 °. Thus, even when a small groove is present in the rotor outer peripheral portion (magnetic pole center outer peripheral portion) on the d-axis, the torque ripple can be sufficiently reduced. The maximum torque is a value that is reduced by 2.5% compared to the case of embodiment 1.

As described above, the structure of each embodiment of the present invention has an effect that torque ripple performance is excellent compared to the case where the torque ripple of the conventional structure using reluctance torque is about 5%, and torque performance is excellent compared to the conventional structure using only magnet torque. That is, the permanent magnet type rotating electrical machine 1 described in each embodiment is configured to effectively reduce torque ripple.

The above-described embodiments provide the following operational advantages.

The permanent magnet type rotating electrical machine 1 may be, for example, an electric power steering motor of an automobile. The permanent magnet type rotating electrical machine 1 may have any of the 10-pole 60-slot distributed windings described in embodiments 1 to 5. Further, since vibration noise can be suppressed and the torque is high, the present invention can be applied to various forms of rotating electrical machines.

The electric auxiliary machine system for an automobile may include the permanent magnet electric rotating machine 1 described above, and further include a control unit that performs electric power steering or electric braking using the permanent magnet electric rotating machine 1. Thus, the electric auxiliary machine system for the automobile can suppress vibration and noise.

The embodiments and the modifications described above are merely examples, and the present invention is not limited to these embodiments as long as the features of the present invention are not impaired. Although the various embodiments and modifications have been described above, the present invention is not limited to these. Other means considered within the scope of the technical idea of the present invention are also included within the scope of the present invention. Description of the reference symbols

1 permanent magnet type rotating electrical machine, 10 stators, 20 rotors, 30 air gaps, 100 stator cores, 110 core back, 130 teeth, 140 windings, 141 first system windings, 142 second system windings, 143 crossover wires, 145 connection portions, 147 first system lead wires, 148 second system lead wires, 200 rotor cores, 201 magnet insertion holes, 210 permanent magnets, 211 magnet stopper portions, 212 magnet receiving portions, 213 air gaps, 220 magnetic pole portions, 219 magnetic pole arcs, 221q axis cores, 230 umbrella cores, 242, bridge 243

connection portions

2, 244 connection portions 1, 250q axis cores outermost peripheral portions, 300 axes.

Claims

1. An embedded permanent magnet type rotating motor comprises a rotor containing a rotor core body and a stator, and is characterized in that,

the rotor core has:

a magnet insertion hole located at each magnetic pole portion and longer in a circumferential direction than in a radial direction;

a magnet stopper portion on an inner peripheral side of both ends of the magnet insertion hole;

a gap on an outer peripheral side of the magnet stopper;

a bridge portion on an outer peripheral side of the gap;

a q-axis core body between the adjacent magnet insertion holes;

a magnet receiving portion of a rectangular shape between magnet stopper portions at both ends of the magnet insertion hole;

an umbrella-shaped core body on the outer peripheral side of the magnet housing section;

a first connection between the umbrella core and the bridge; and

a second connecting portion between the q-axis core and the bridge portion,

the outer peripheral portion of the rotor core sandwiched between two imaginary q-axis direction straight lines passing through both ends of the minimum width Wq in the q-axis vertical direction of the q-axis core is positioned on a circle having a radius substantially coincident with the rotor radius with the rotation axis as the center,

the outer peripheral profiles of the core body of the umbrella-shaped core body, the first connecting portion and the bridge portion are formed by circular arcs,

the width Wb of the bridging portion is smaller than the radial length Tmg/2 of the magnet receiving portion,

the radial thickness Hc of the center of the magnetic pole of the umbrella-shaped core is in the range of 0.5 to 1.0 times of the radial thickness Hcm of the imaginary arc when the central angle of the arc is enlarged to the pole pitch end,

the central angle of the Wq is in the range of 0.4 to 0.9 times of pi/(3 times of pole number),

and the Wq is within the range of 1.15-2.5 times of the Hc.

2. An embedded permanent magnet type rotating electrical machine according to claim 1, further comprising:

a first system winding connected to a first drive circuit including one or more three-phase inverters; and

a second system winding connected to a second drive circuit comprising more than one three-phase inverter.

3. An embedded permanent magnet type rotating electric machine according to claim 1,

the rotor core has a symmetrical shape with respect to a pole center line,

the number of poles of the permanent magnet embedded type rotating electric machine is any one of 8 poles, 10 poles, 12 poles and 14 poles.

4. An embedded permanent magnet type rotating electric machine according to claim 1 or 2,

the outer periphery of the rotor core is a perfect circle.

5. An embedded permanent magnet type rotating electric machine according to claim 1 or 2,

the outer peripheral profiles of the core body of the umbrella-shaped core body, the first connecting portion and the bridge portion are formed by arcs, and the radius of the arcs is smaller than the radius of the rotor.

6. An embedded permanent magnet type rotating electric machine according to claim 1 or 2,

a groove is arranged on the periphery of the center of the magnetic pole,

the core outer circumferential profiles of the umbrella-shaped core, the first connecting portion, and the bridge portion other than the groove are formed by circular arcs.

7. An embedded permanent magnet type rotating electric machine according to claim 1 or 2,

the Hc is within the range of 0.55 to 0.9 times of the Hcm,

the central angle of the Wq is in the range of 0.5 to 0.75 times of pi/(3 times of pole number),

and the Wq is within the range of 1.2-2.1 times of the Hc.

8. An embedded permanent magnet type rotating electric machine according to claim 2,

the first system winding and the second system winding are disposed on the stator core in a distributed winding manner and are separately disposed on an inner circumferential side and an outer circumferential side of the stator core,

and the current phase difference of the first system winding and the second system winding is in the range of 24-36 degrees.

9. An embedded permanent magnet type rotating electrical machine according to claim 1, further comprising:

a first system winding connected to the first inverter,

A second system winding connected to the second inverter,

A third system winding connected to a third inverter, an

A fourth system winding connected to the fourth inverter.

10. An embedded permanent magnet type rotating electric machine according to claim 1 or 2,

tb represents the thickness of the electromagnetic steel sheet forming the laminated core,

Hc-Wb + Tb/2 is within the range of 0.5-0.8 times of Hcm,

the Wq is in the range of 0.4 to 0.9 times of pi multiplied by the radius of the rotor/(3 multiplied by the number of poles),

and the Wq is within the range of 1.2-2.5 times of Hc-Wb + Tb/2.

11. An embedded permanent magnet type rotating electric machine according to claim 10,

the central angle of the length Wmg on the outer peripheral side of the magnet housing part is in the range of 7/8-1 times of 4 pi/(3 times of the pole number),

the center angle of the distance We between the outer peripheral end point of the magnet housing part and the outer peripheral part of the q-axis core body is more than 0.5 times of pi/(3 times of pole number),

the bridge portion has a generally constant width Wb,

the length of the bridge part has a central angle of (pi/6 x pole number) × 0.6 or more,

the Wb is below the Tb.

12. An electric auxiliary machine system for an automobile, characterized by comprising:

an embedded permanent magnet type rotating electrical machine according to claim 1 or 2; and

and a control unit that performs electric power steering or electric braking using the embedded permanent magnet type rotating electric machine.