US-12620846-B2 - Permanent magnet-type rotary electric machine

Abstract

A permanent magnet-type rotary electric machine comprises: a stator including: a stator core having a plurality of stator teeth formed circumferentially; stator coils arranged in the respective bottoms of a plurality of stator slots formed between the stator teeth and wound on the stator teeth in a concentrated winding manner; and stator magnets arranged near the respective openings of the plurality of stator slots, a first rotor having a plurality of pole pieces and disposed coaxially with the stator to face the stator magnets; and a second rotor having a plurality of permanent magnets and disposed coaxially with the first rotor to face the first rotor, wherein the circumferential width of stator teeth positioned between the adjacent two of the stator magnets is narrower than the circumferential width of the stator slots.

Inventors

• Haruyuki Kometani
• Ryoji MIYATAKE
• Atsushi Yamamoto
• Noboru Niguchi
• Katsuhiro Hirata
• Hironori Suzuki
• Takuya Ito

Assignees

• MITSUBISHI ELECTRIC CORPORATION
• OSAKA UNIVERSITY

Dates

Publication Date

20260505

Application Date

20211118

Claims (7)

1. 1 . A permanent magnet-type rotary electric machine comprising: a stator including: a stator core having a plurality of stator teeth formed in a circumferential direction; stator coils arranged on respective bottom sides of a plurality of stator slots formed between the stator teeth and wound on the stator teeth in a concentrated winding manner; and stator magnets having the same polarity in a radial direction and arranged on respective opening sides of the plurality of stator slots, a first rotor having a plurality of pole pieces and disposed coaxially with the stator to face the stator magnets; and a second rotor having a plurality of permanent magnets and disposed coaxially with the first rotor to face the first rotor, wherein circumferential width of the stator teeth positioned between the stator magnets arranged in adjacent stator slots among the plurality of stator slots are narrower than circumferential width of the stator slots, and wherein the stator teeth and the stator magnets are interspaced from each other, and circumferential interspace width is gradually increased toward an inner circumference.
2. 2 . A permanent magnet-type rotary electric machine comprising: a stator including: a stator core having a plurality of stator teeth formed in a circumferential direction; stator coils arranged on respective bottom sides of a plurality of stator slots formed between the stator teeth and wound on the stator teeth in a concentrated winding manner; and stator magnets having the same polarity in a radial direction and arranged on respective opening sides of the plurality of stator slots, a first rotor having a plurality of pole pieces and disposed coaxially with the stator to face the stator magnets; and a second rotor having a plurality of permanent magnets and disposed coaxially with the first rotor to face the first rotor, wherein at a position facing the first rotor, a circumferential width of the stator teeth are narrower than a circumferential width of the stator slots, wherein the stator teeth positioned between the stator magnets arranged in adjacent stator slots among the plurality of the stator slots are tapered in circumferential width toward an inner circumference, and wherein the stator teeth and the stator magnets are interspaced from each other, and circumferential interspace width is gradually increased toward an inner circumference.
3. 3 . The permanent magnet-type rotary electric machine of claim 2 , wherein a circumferential width at an outermost circumference, of the stator teeth positioned between the stator magnets is wider than a circumferential width at the same radial position, of the stator slots.
4. 4 . The permanent magnet-type rotary electric machine of claim 1 , wherein the stator magnets are tapered in circumferential width toward an inner circumference.
5. 5 . The permanent magnet-type rotary electric machine of claim 1 , wherein the number N S of stator slots of the stator, the number N L of pole pieces of the first rotor, and the number N H of pole pairs of the second rotor satisfy N L =N S +N H .
6. 6 . The permanent magnet-type rotary electric machine of claim 2 , wherein the stator magnets are tapered in circumferential width toward an inner circumference.
7. 7 . The permanent magnet-type rotary electric machine of claim 2 , wherein the number N S of stator slots of the stator, the number N L of pole pieces of the first rotor, and the number N H of pole pairs of the second rotor satisfy N L =N S +N H .

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is based on PCT filing PCT/JP2021/042377, filed Nov. 18, 2021, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present application relates to a permanent magnet-type rotary electric machine. BACKGROUND ARTS There has been a rotary electric machine that is capable of changing the rotation speed of the rotor with the stator and the rotors being in no contact with each other. For example, such a rotary electric machine that is a magnetic wave gear machine is disclosed in Patent Document 1. The magnetic wave gear machine disclosed in Patent Document 1 includes a stator, a first rotor that rotates at a low speed, and a second rotor that rotates at a high speed depending on a speed change ratio. The stator, the first rotor, and the second rotor are disposed about the rotation axis in this order from the outer circumference. The stator is provided with stator coils. The stator coils are for outputting generated electric power or for controlling generated torque. According to the magnetic wave gear machine disclosed in Patent Document 1, since the speed of the second rotor can be changed with the first rotor and the second rotor being in no contact with the stator, a mechanical transmission is eliminated and maintenance loads for coping with mechanical wear and the like can be mitigated. PRIOR ART DOCUMENT Patent Documents Patent Document 1: JP2016-135014APatent Document 2: WO2020-174936A SUMMARY OF THE INVENTION Problem that the Invention is to Solve The rotary electric machine disclosed in Patent Document 1 has a plurality of stator slots in the stator, and the stator coils and stator magnets (permanent magnets) are accommodated in the respective stator slots. The stator magnets in the respective stator slots are magnetized in the same direction. The first rotor having a plurality of pole pieces arranged circumferentially is disposed near the inner circumference of the stator, and the second rotor having permanent magnets is disposed near the inner circumference of the first rotor. Expressing the number of stator slots (=the number of stator teeth) of the stator as NS, the number of pole pieces of the first rotor as NL, and the number of pole pairs of the second rotor as NH, the following mathematical relationship is satisfied: NL=NS+NH. In this case, the second rotor rotates at a speed NL/NH times the first rotor. In the rotary electric machine disclosed in Patent Document 1, however, the stator coils are wound on the stator in a distributed winding manner. Stator coils wound in a distributed winding manner, when the stator diameter is increased with increasing capacity, are reduced in workability. Hence, in a case of the capacity of the rotary electric machine being increased, workability of the stator coils is reduced. On the other hand, in a case of the stator coils wound in a concentrated winding manner, although the capacity is increased, reduction in workability of the stator coils is suppressed. For this reason, in order to suppress the reduction in workability of the stator coils, the stator coils of the rotary electric machine are preferably wound in a concentrated winding manner. In a case of operating as a generator the rotary electric machine disclosed in Patent Document 1, when the first rotor is rotated by an external power, the magnetic force of the stator magnets and the magnetic force of the second rotor magnets are modulated by the plurality of pole pieces of the first rotor, whereby the second rotor is rotated at an increased speed. Linkage of magnetic force generated from the permanent magnets of the second rotor increased in speed with the stator coils induces a generated power in the stator coils. That is, increasing the rotation speed of the second rotor or linking more magnetic force of the permanent magnets of the second rotor with the stator coils by narrowing the air gaps from the second rotor to the stator increases induced voltage and results in increase of the generated power. Input is generated by rotating the first rotor by an external power: (speed of the first rotor)×(torque acting on the first rotor). Since the torque is generated in the first rotor by modulation of the magnetic force from the stator magnets and the magnetic force from the permanent magnets of the second rotor by the pole pieces of the first rotor, in order to obtain a necessary output, the torque generated in the first rotor needs to be a predetermined value depending on the rotation speed. That is, by increasing the torque generated in the first rotor, the capacity can be increased. Generally, considering a generator of large capacity of megawatt-class reveals that the machine size or the amount of permanent magnets to be used is affected not by induced electromotive force (hereinafter, referred to as induced voltage) proportional to magnetic flux generated from the second rotor that links with the above-mentioned s