# US 2021/0242736 A1 · Motor rotor structure and permanent magnet motor

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- Number: US 2021/0242736 A1
- Document ID: US20210242736A1
- Status: Published application
- Kind: A1
- Application number: 17/236,120
- Filed: 2021-04-21
- Published: 2021-08-05
- Earliest claimed: 2018-11-14
- Assignees: Gree Electric Appliances, Inc. of Zhuhai
- Applicants: Gree Electric Appliances, Inc. of Zhuhai
- Inventors: Min WANG; Yong XIAO; Quanfeng LI
- Web page: https://patentgrep.com/patent/US20210242736A1

## CPC

- H02K 1/2753: the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K 1/276: Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
- H02K 1/26: Rotor cores with slots for windings
- H02K 21/046: {with rotating permanent magnets and stationary field winding}
- H02K 21/10: Rotating armatures
- H02K 1/246: {Variable reluctance rotors}
- H02K 1/27: Rotor cores with permanent magnets
- H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information
- H02K 2213/09: Machines characterised by the presence of elements which are subject to variation, e.g. adjustable bearings, reconfigurable windings, variable pitch ventilators
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

Disclosed is a motor rotor structure including a rotor core. A plurality of radial slots each are in the rotor core along a circumferential direction, and a first flux barrier slot is provided between every two adjacent radial slots. Two kinds of permanent magnets having different coercivities mounted in each radial slot. The two kinds of permanent magnets having different coercivities are distributed along a radial direction of the rotor core. The two kinds of permanent magnets having different coercivities are both magnetized along a tangential direction of the rotor core. A second flux barrier slot is provided between the two kinds of permanent magnets having different coercivities.

## Claims

### Claim 1

A motor rotor structure, comprising a rotor core, wherein:
a plurality of radial slots are provided in the rotor core along a circumferential direction, and a first flux barrier slot is provided between every two adjacent radial slots;
two kinds of permanent magnets having different coercivities are mounted in each radial slot of the plurality of radial slots; the two kinds of permanent magnets having different coercivities are distributed along a radial direction of the rotor core; the two kinds of permanent magnets having different coercivities are both magnetized along a tangential direction of the rotor core; a second flux barrier slot is provided between the two kinds of permanent magnets having different coercivities; and
when magnetization directions of the two kinds of permanent magnets having different coercivities are opposite, the rotor core is in a more-magnetic-pole state, and when the magnetization directions of the two kinds of permanent magnets having different coercivities are identical, the rotor core is in a fewer-magnetic-pole state.

### Claim 2 (depends on 1)

The motor rotor structure according to claim 1, wherein the two kinds of permanent magnets having different coercivities comprise a lower-coercivity permanent magnet and a higher-coercivity permanent magnet; the lower-coercivity permanent magnet is arranged in one side of the radial slots proximate to an outer circle of the motor rotor structure; and the higher-coercivity permanent magnet is arranged in another side of the radial slot proximate to an inner circle of the motor rotor structure.

### Claim 3 (depends on 1)

The motor rotor structure according to claim 1, wherein when the rotor core is in the fewer-magnetic-pole state, a number of magnetic poles of the rotor core is n, and when the rotor core is in the more-magnetic-pole state, a number of magnetic poles of the rotor core is 2n.

### Claim 4 (depends on 1)

The motor rotor structure according to claim 1, wherein the two kinds of permanent magnets having different coercivities comprise a lower-coercivity permanent magnet and a higher-coercivity permanent magnet; the lower-coercivity permanent magnet has a coercivity H1 and a thickness d1, and the higher-coercivity permanent magnet has a coercivity H2 and a thickness d2; and d2×H2/H1×0.9<d1<d2×H2/H1×1.1 is satisfied.

### Claim 5 (depends on 1)

The motor rotor structure according to claim 1, wherein the two kinds of permanent magnets having different coercivities comprise a lower-coercivity permanent magnet and a higher-coercivity permanent magnet; the lower-coercivity permanent magnet has remanence Br1 and a width L1, and the higher-coercivity permanent magnet has remanence Br2 and a width L2; and L2×Br2/Br1×0.9<L1<L2×Br2/Br1×1.1 is satisfied.

### Claim 6 (depends on 1)

The motor rotor structure according to claim 1, wherein two ends of the second flux barrier slot in a width direction of the second flux barrier slot are both proximate to an outer circle of the motor rotor structure.

### Claim 7 (depends on 6)

The motor rotor structure according to claim 6, further comprising third flux barrier slots arranged on two ends of the second flux barrier slot proximate to the outer circle of the motor rotor structure; and a width direction of each of the third flux barrier slots is parallel to a tangential direction of the rotor core corresponding to a position where each of the third flux barrier slots is located.

### Claim 8 (depends on 7)

The motor rotor structure according to claim 7, wherein each of the third flux barrier slots have a thickness ranging from 2 g to 5 g, and g denotes a motor air gap.

### Claim 9 (depends on 7)

The motor rotor structure according to claim 7, wherein d denotes a thickness of one side of the radial slot proximate to the outer circle of the motor rotor structure, and L3 denotes a width of each of the third flux barrier slots; and 0.8×d<L4<1.2×d is satisfied.

### Claim 10 (depends on 1)

The motor rotor structure according to claim 1, wherein the second flux barrier slot has a thickness ranging from 2 g to 5 g, and g denotes a motor air gap.

### Claim 11 (depends on 1)

The motor rotor structure according to claim 1, wherein a central angle between a center of one end of the second flux barrier slot proximate to an outer circle of the motor rotor structure and a center of one end of the radial slot proximate to the outer circle of the motor rotor structure is α, 0.9×π/n<α<1.1×π/n is satisfied, and n denotes a number of magnetic poles of the rotor core in the fewer-magnetic-pole state.

### Claim 12 (depends on 1)

The motor rotor structure according to claim 1, wherein two ends of the first flux barrier slot along a radial direction of the rotor core are proximate to an inner circle of the motor rotor structure and an outer circle of the rotor, respectively, and a thickness of one end of the first flux barrier slot proximate to the inner circle of the rotor is greater than a thickness of another end of the first flux barrier slot proximate to the outer circle of the motor rotor structure.

### Claim 13 (depends on 12)

The motor rotor structure according to claim 12, further comprising a fourth flux barrier slot arranged on the other end of the first flux barrier slot proximate to the outer circle of the motor rotor structure, and a width direction of the fourth flux barrier slot is parallel to a tangential direction of the rotor core corresponding to a position where the fourth flux barrier slot is located.

### Claim 14

A permanent magnet motor, comprising a stator core and a motor rotor structure, wherein:
the motor rotor structure further comprises a rotor core;
a plurality of radial slots are provided in the rotor core along a circumferential direction, and a first flux barrier slot is provided between every two adjacent radial slots;
two kinds of permanent magnets having different coercivities are mounted in each radial slot of the plurality of radial slots; the two kinds of permanent magnets having different coercivities are distributed along a radial direction of the rotor core; the two kinds of permanent magnets having different coercivities are both magnetized along a tangential direction of the rotor core; a second flux barrier slot is provided between the two kinds of permanent magnets having different coercivities; and
when magnetization directions of the two kinds of permanent magnets having different coercivities are opposite, the rotor core is in a more-magnetic-pole state, and when the magnetization directions of the two kinds of permanent magnets having different coercivities are identical, the rotor core is in a fewer-magnetic-pole state.

### Claim 15 (depends on 14)

The permanent magnet motor according to claim 14, wherein the two kinds of permanent magnets having different coercivities comprise a lower-coercivity permanent magnet and a higher-coercivity permanent magnet; the lower-coercivity permanent magnet is arranged in one side of the radial slots proximate to an outer circle of the motor rotor structure; and the higher-coercivity permanent magnet is arranged in another side of the radial slot proximate to an inner circle of the motor rotor structure.

### Claim 16 (depends on 14)

The permanent magnet motor according to claim 14, wherein when the rotor core is in the fewer-magnetic-pole state, a number of magnetic poles of the rotor core is n, and when the rotor core is in the more-magnetic-pole state, a number of magnetic poles of the rotor core is 2n.

### Claim 17 (depends on 14)

The permanent magnet motor according to claim 14, wherein the two kinds of permanent magnets having different coercivities comprise a lower-coercivity permanent magnet and a higher-coercivity permanent magnet; the lower-coercivity permanent magnet has a coercivity H1 and a thickness d1, and the higher-coercivity permanent magnet has a coercivity H2 and a thickness d2; and d2×H2/H1×0.9<d1<d2×H2/H1×1.1 is satisfied.

### Claim 18 (depends on 14)

The permanent magnet motor according to claim 14, wherein the two kinds of permanent magnets having different coercivities comprise a lower-coercivity permanent magnet and a higher-coercivity permanent magnet; the lower-coercivity permanent magnet has remanence Br1 and a width L1, and the higher-coercivity permanent magnet has remanence Br2 and a width L2; and L2×Br2/Br1×0.9<L1<L2×Br2/Br1×1.1 is satisfied.

### Claim 19 (depends on 14)

The permanent magnet motor according to claim 14, wherein two ends of the second flux barrier slot in a width direction of the second flux barrier slot are both proximate to an outer circle of the motor rotor structure.

### Claim 20 (depends on 19)

The permanent magnet motor according to claim 19, further comprising third flux barrier slots arranged on two ends of the second flux barrier slot proximate to the outer circle of the motor rotor structure; and a width direction of each of the third flux barrier slots is parallel to a tangential direction of the rotor core corresponding to a position where each of the third flux barrier slots is located.