Electric machine with Q-offset grooved interior-magnet rotor and vehicle

• US 9,300,176 B2
• Filed: 10/14/2009
• Issued: 03/29/2016
• Est. Priority Date: 10/16/2008
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: Saito, Yasuyuki, Goto, Tsuyoshi, Nakayama, Kenichi, Sugimoto, Shinji, Hino, Noriaki
• Primary Examiner(s): Mullins, Burton
• Assistant Examiner(s): Carter, Mark R
• Application Number:
  US13/124,502
• Publication Number:
  US 20110254474A1
• Time in Patent Office: 2,358 Days
• Field of Search: 310/181, 310/156.53, 310/156.54, 310/156.49
• US Class Current: 1/1
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/26 characterised by the motors or the generators
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 15/007 Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2220/14 Synchronous machines
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/429 Current
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2270/142 acoustic
• CPC Class Codes: B60L 2270/145 Structure borne vibrations
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: H02K 1/24 Rotor cores with salient poles ; Variable reluctance rotors
• CPC Class Codes: H02K 1/276 : Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
• CPC Class Codes: H02K 1/2766 : having a flux concentration effect
• CPC Class Codes: H02K 2201/06 : Magnetic cores, or permanent magnets characterised by their skew
• CPC Class Codes: H02K 2213/03 : Machines characterised by numerical values, ranges, mathematical expressions or similar information
• CPC Class Codes: H02K 29/03 : with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
• CPC Class Codes: H02K 7/006 : Structural association of a motor or generator with the drive train of a motor vehicle
• CPC Class Codes: H02P 27/06 : using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A rotating electric machine includes a stator having a stator coil and a rotor provided rotatably around a specific rotation axis with respect to the stator. The rotor includes a plurality of magnets, a plurality of magnetically-assisted salient pole members provided between poles of any adjacent two magnets from among the plurality of magnets, and a magnetoresistance variation unit provided in the magnetically-assisted salient pole member along an axial direction of the rotation axis at a position offset in a circumferential direction of the rotation axis from a q-axis passing through a salient pole center of the magnetically-assisted salient pole member. The amount of offset of the magnetoresistance variation unit from the q-axis varies depending on positions of the magnetically-assisted salient pole members so that torque fluctuations cancel each other when power is applied.

Claims

1. A rotating electric machine comprising:

a stator having a stator coil; and

a rotor provided rotatably around a specific rotation axis with respect to the stator, wherein

the rotor includes;

a plurality of magnets;

a plurality of holes in which the magnets are provided;

wherein the plurality of magnets are arranged in regions of alternating polarity, wherein each of said regions has at least one magnet;

a plurality of magnetically-assisted salient pole members, each of which is provided in a core portion between the regions;

a first magnetic air gap formed with an edge of each of the magnets and the holes; and

a second magnetic air gap provided in each of the magnetically-assisted salient pole members along an axial direction of the rotation axis at a position offset in a circumferential direction of the rotation axis from a q-axis passing through a salient pole center of each of the magnetically-assisted salient pole members, wherein

the second magnetic air gap is formed independently from the first magnetic air gap; and

the second magnetic air gap has an amount of offset from the q-axis in a cross section perpendicular to the rotation axis, the amount of offset varying depending on positions of the magnetically-assisted salient pole members so that torque fluctuations in the cross section cancel each other when power is applied.

2. A rotating electric machine according to claim 1, wherein the circumferential positions of the magnets in the rotor are constant regardless of the positions in the axial direction.

3. A rotating electric machine according to claim 1, wherein the rotor is divided into a plurality of axial-direction split cores that are provided along the axial direction and each of which has at least one of the magnets, the magnetically-assisted salient pole member, and the second magnetic air gap, and

the circumferential positions of the magnets in the axial-direction split cores are constant regardless of the positions in the axial direction.

4. A rotating electric machine according to claim 3, wherein

the rotor includes a plurality of core groups each consisting of a plurality of the axial-direction split cores that have substantially the same positions of the second magnetic air gaps in the circumferential direction, and

a sum of thicknesses of the plurality of axial-direction split cores constituting the core group in the axial direction is constant for each of the plurality of core groups.

5. A rotating electric machine according to claim 1, wherein the second magnetic air gap is a concave formed on a surface of the rotor.

6. A rotating electric machine according to claim 5, wherein

the concave has a width angle in the circumferential direction that is within the range of ¼

to ½

times a pitch angle between any adjacent two teeth provided in the stator.

7. A rotating electric machine according to claim 1, wherein the second magnetic air gap is a hole formed on a surface of the rotor.

8. A rotating electric machine according to claim 1, wherein

the plurality of magnets is arranged in the circumferential direction such that a direction of magnetization of each magnet is in a radial direction of the rotor that is perpendicular to the axial direction and an orientation of magnetization of each magnet is alternately reversed.

9. A rotating electric machine according to claim 8, wherein

each of the magnets constitutes a magnet group consisting of a plurality of magnets having substantially the same orientation of magnetization.

10. A rotating electric machine according to claim 1, wherein each of the magnetically-assisted salient pole members is provided with a plurality of the second magnetic air gaps.

11. A rotating electric machine according to claim 1, wherein the second magnetic air gaps are arranged asymmetrically with respect to the q-axis passing through the salient pole center and symmetrically with respect to a d-axis passing through a magnetic pole center of the magnet.

12. A rotating electric machine according to claim 1, wherein the second magnetic air gaps are arranged symmetrically with respect to the q-axis passing through the salient pole center and asymmetrically with respect to a d-axis passing through a magnetic pole center of the magnet.

13. A rotating electric machine according to claim 1, wherein

the rotor includes a plurality of rotor cores each including a laminate of electromagnetic steel sheets each provided with a hole or recess that constitutes the second magnetic air gap.

14. A rotating electric machine according to claim 13, wherein

each of the rotor cores has different position of the second magnetic air gap depending on the position in the axial direction by offsetting the electromagnetic steel sheets in the circumferential direction by a unit of magnetic pole pitch of the magnet.

15. A rotating electric machine according to claim 1, wherein the rotor includes a first skew structure in which the magnets are arranged offset in the circumferential direction corresponding to the axial positions of the magnets and a second skew structure in which the second magnetic air gaps are arranged offset in the circumferential direction corresponding to the axial positions of the second magnetic air gaps.

16. A rotating electric machine according to claim 1, wherein

the stator coil is wound by distributed winding.

17. An electric vehicle comprising:

a rotating electric machine, including

a stator having a stator coil; and

a rotor provided rotatable around a specific rotation axis with respect to the stator, wherein the rotor includes;

a plurality of magnets;

a plurality of holes in which the magnets are provided;

wherein the plurality of magnets are arranged in regions of alternating polarity, wherein each of said regions has at least one magnet;

a plurality of magnetically-assisted salient pole members, each of which is provided in a core portion between the regions;

a first magnetic air gap formed with an edge of each of the magnets and the holes; and

a second magnetic air gap provided in each of the magnetically-assisted salient pole members along an axial direction of the rotation axis at a position offset in a circumferential direction of the rotation axis from a q-axis passing through a salient pole center of each of the magnetically-assisted salient pole members, wherein

the second magnetic air gap is formed independently from the first magnetic air gap; and

the second magnetic air gap has an amount of offset from the q-axis in a cross section perpendicular to the rotation axis, the amount of offset varying depending on positions of the magnetically-assisted salient pole members so that torque fluctuations in the cross section cancel each other when power is applied;

a battery that supplies direct current power; and

a conversion unit that converts the direct current power of the battery into an alternating current power and supplies the alternating current power to the rotating electric machine, wherein

a torque of the rotating electric machine is utilized as a driving force.