Rotor and permanent magnet motor

Disclosed are a rotor and a permanent magnet motor. The rotor includes a rotor core, at least two first permanent magnets and at least two second permanent magnets. A coercivity of each first permanent magnet is different from a coercivity of each second permanent magnet, the at least two first permanent magnets and the at least two second permanent magnets are arranged in an axial direction in magnetic steel slots of the rotor core. One of the first permanent magnets and one of the second permanent magnets are arranged to be connected in series in a radial direction of the rotor core in one slot to form a permanent magnet pole. A consequent pole is formed between every two adjacent permanent magnet poles, and the permanent magnet pole forms a magnetic circuit passing through the consequent pole.

FIELD

The present disclosure relates to the field of driving device technologies, more particularly, to a rotor and a permanent magnet motor.

BACKGROUND

A permanent magnet motor mainly includes a stator and a rotor. The rotor includes a rotor core and a permanent magnet. The permanent magnet is mounted in a magnetic steel slot of the rotor core. When a symmetrical three-phase current is connected to the stator, a three-phase stator current generates a rotating magnetic field in space because three phases of the stator differ in spatial positions by 120°, and the rotor in the rotating magnetic field moves under the action of the electromagnetic force, and in this case, electrical energy is transformed into kinetic energy. When the permanent magnet generates the rotating magnetic field, a three-phase stator winding induces the symmetrical three-phase current by means of an armature reaction under the action of the rotating magnetic field, and in this case, the kinetic energy of the rotor is transformed into the electrical energy.

Since the magnetic field provided by the permanent magnet of the traditional permanent magnet motor is fixed, the magnetic field inside the permanent magnet motor is difficult to adjust, so it is difficult for the permanent magnet motor to balance the efficiency at a high frequency and the efficiency at a low frequency, and the maximum operating frequency of the permanent magnet motor is limited when a power supply voltage is fixed.

SUMMARY

Based on this, a rotor and a permanent magnet motor that can balance the efficiency at a high frequency and the frequency at a low frequency are provided with respect to the problem that it is difficult for the traditional permanent magnet motor to balance the efficiency at the high frequency and the efficiency at the low frequency.

A rotor includes:a rotor core provided with magnetic steel slots, the magnetic steel slots being arranged at intervals on an axial end face of the rotor core in a circumferential direction of the rotor core;at least two first permanent magnets and at least two second permanent magnets, where a coercivity of each first permanent magnet is different from a coercivity of each second permanent magnet; the at least two first permanent magnets and the at least two second permanent magnets are arranged in an axial direction in the magnetic steel slots of the rotor core; one of the first permanent magnets and one of the second permanent magnets are arranged in series in a radial direction of the rotor core in one slot to form a permanent magnet pole;a circumferential part of the rotor core located between every two adjacent permanent magnet poles forms a consequent pole, and the permanent magnet pole form a magnetic circuit passing through the consequent pole.

In some embodiments, the coercivity of each first permanent magnet is less than the coercivity of each second permanent magnet, and in each of magnetic steel slots, the first permanent magnet is located on one side farther away from a center of the rotor core in the radial direction of the rotor core than a corresponding second permanent magnets is.

In some embodiments, the magnetic steel slots are uniformly arranged at intervals on the axial end face of the rotor core in the circumferential direction of the rotor core.

In some embodiments, a direction of the permanent magnet pole is arranged in the radial direction of the rotor core.

In some embodiments, the first permanent magnet and the second permanent magnet in each of magnetic slots are arranged in layers in the radial direction of the rotor core.

In some embodiments, in each of magnetic steel slots and in the circumferential direction of the rotor core, two ends of the first permanent magnet are flush with corresponding two ends of the second permanent magnet.

In some embodiments, a cross section of the permanent magnet pole is in a shape of a rectangle or is V-shaped, and the V-shaped cross section has an opening that opens outwards from the center of the rotor core.

In some embodiments, a first central angle is formed by straight lines connecting the center of the rotor core and two ends of each of the permanent magnet pole respectively, and the two ends of each of the permanent magnet pole is in the circumferential direction of the rotor core; and the first central angle is greater than π/p and less than 1.57π/p; and p is equal to half of a sum of a number of the permanent magnet poles and a number of the consequent poles.

In some embodiments, a magnetic isolation slot is provided on the axial end face of the rotor core, and the magnetic isolation slot extends in the circumferential direction of the rotor core (10) starting from two ends of the permanent magnet pole.

A permanent magnet motor is provided and includes a stator and the rotor as described above, and the rotor is rotatably sleeved in the stator.

In the rotor and the permanent magnet motor provided by the present disclosure, the permanent magnet pole is formed by the first permanent magnet and the second permanent magnet connected in series in a radial direction of the rotor core, and the magnetization degree of the permanent magnet with a low coercivity is reduced by means of the magnetizing current, thus achieving the effects that the magnetic field intensity of the permanent magnet motor is adjustable, and the permanent magnet motor balances the efficiency at the high frequency and the efficiency at the low frequency. Moreover, as the permanent magnet pole is combined with the consequent pole, when the magnetic field of the permanent magnet motor is adjusted by means of the magnetizing current, a circuit passing through the permanent magnet pole and the consequent pole is formed. No permanent magnet is arranged at the consequent pole, so the interference to the circuit is reduced, and the difficulty of magnetizing the permanent magnet with the lower coercivity is thus reduced. Due to the existence of the consequent pole, the permanent magnet poles exist alternately, thus the number of permanent magnets is greatly reduced.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To facilitate understanding of the present disclosure, a more comprehensive description of the present disclosure will be given below with reference to the relevant drawings. Some embodiments of the present disclosure are given in the drawings. However, the present disclosure may be implemented in many different forms but is not limited to the embodiments described herein. Rather, these embodiments are provided to make the contents disclosed in the present disclosure more fully understood.

It should be noted that when one element is referred to as “attached to” another element, it may be directly disposed on the other element or an intermediate element may exist. When one element is considered to be “connected to” another element, it may be directly connected to the other element or an intermediate element may co-exist. The terms “vertical”, “horizontal”, “left”, “right” and similar expressions used herein are for illustrative purposes only.

The terms used herein in the specification of the present disclosure are for the purpose of describing specific embodiments only but not intended to limit the present disclosure. The term “and/or” used herein includes any and all combinations of one or more related listed items.

Referring toFIG.1andFIG.2, an embodiment of the present disclosure provides a permanent magnet motor, including a stator and a rotor100. The rotor100is coaxially sleeved inside the stator, and there is an air gap between the rotor100and the stator to make it easier for the rotor100to rotate relative to the stator.

In an embodiment, the stator includes a stator core and armature windings. The stator core is formed by punched and pressed soft magnetic silicon steel sheets, and the teeth are circumferentially arranged at intervals inside the stator core. Each tooth is wound with an armature winding. The armature winding is electrified to generate a rotating magnetic field, which is applied to the rotor100to force the rotor100to rotate.

In an embodiment, the rotor100includes a rotor core10and permanent magnets. The rotor core10is formed by punched and pressed soft magnetic silicon steel sheets, and the permanent magnets are axially arranged on an axial end face of the rotor core10. In one embodiment, the axial end face of the rotor core10is provided with magnetic steel slots11, and the permanent magnets are arranged in an axial direction in the magnetic steel slots11of the rotor core10.

In an embodiment, the magnetic steel slots11are arranged at intervals on the axial end face of the rotor core10in a circumferential direction of the rotor core10.

In an embodiment, the permanent magnets include a first permanent magnet20and a second permanent magnet30. A coercivity of the first permanent magnet20is different from that of the second permanent magnet30, and the number of the first permanent magnets20is the same as that of the second permanent magnets30and is at least two. One first permanent magnet20and one second permanent magnet30are both mounted in one magnetic steel slot11, and the first permanent magnet20and the second permanent magnet disposed in the same magnetic steel slot11are arranged in series in the radial direction of the rotor core10and jointly form a permanent magnet pole40.

In an embodiment, a circumferential part of the rotor core10located between every two adjacent permanent magnet poles40forms a consequent pole50(the consequent pole50is formed by the part of the rotor core10where no permanent magnet is provided), and the permanent magnet pole40forms a magnetic circuit passing through a stator and the consequent pole50.

In the permanent magnet motor provided by the present embodiment, the permanent magnet pole40is formed by the first permanent magnet20and the second permanent magnet30connected in series in a radial direction of the rotor core10, and the coercivity of the first permanent magnet20is different from that of the second permanent magnet30. Therefore, when the permanent magnet motor is in a low-speed and large-torque state, the permanent magnet with a low coercivity may be magnetized by a magnetizing current to become saturated, so that the magnetic field intensity inside the permanent magnet motor is enhanced to meet requirements. When the permanent magnet motor runs at a high speed and with a low torque, the magnetization degree of the permanent magnet with a low coercivity is reduced by means of the magnetizing current, so that the magnetic field intensity inside the permanent magnet motor is reduced to meet requirements. In this way, the magnetic field intensity of the permanent magnet motor is adjustable, and the permanent magnet motor balances the efficiency at the high frequency and the efficiency at the low frequency. Moreover, the first permanent magnet20and the second permanent magnet30are arranged in series along the radial direction of the rotor core10, improving the anti-demagnetization capability of the permanent magnet with the lower coercivity. Moreover, as the permanent magnet pole40is combined with the consequent pole50, when the magnetic field of the permanent magnet motor is adjusted by means of the magnetizing current, a circuit passing through the permanent magnet pole40and the consequent pole50is formed. No permanent magnet is arranged at the consequent pole50, so the interference to the circuit is reduced, and the difficulty of magnetizing the permanent magnet with the lower coercivity is thus reduced. Due to the existence of the consequent pole50, the permanent magnet poles40exist alternately, thus the number of permanent magnets is greatly reduced.

Further, in an embodiment, the magnetic steel slots11are uniformly arranged at intervals in the circumferential direction of the rotor core10. Correspondingly, in the circumferential direction of the rotor core10, the at least two first permanent magnets20are uniformly arranged at intervals, and the at least two second permanent magnets30are uniformly arranged at intervals.

In an embodiment, at least three magnetic steel slots11are provided. Correspondingly, at least three first permanent magnets20and at least three second permanent magnets30are also provided.

In an embodiment, the center of a shape formed by straight lines connecting centers of at least three magnetic steel slots11successively coincides with the center of the rotor core10. In this case, the center of a shape formed by straight lines connecting centers of the first permanent magnets20mounted in the at least 3 magnetic steel slots11successively coincides with the center of the rotor core10, and the center of a shape formed by straight lines connecting centers of the second permanent magnets30mounted in the at least 3 magnetic steel slots11successively also coincides with the center of the rotor core10.

In an embodiment, the first permanent magnet20and the second permanent magnet30disposed in the magnetic steel slot11are arranged in layers in the radial direction of the rotor core10, to ensure an effect of a series connection of the first permanent magnet20and the second permanent magnet30.

Further, in an embodiment, for the first permanent magnet20and the second permanent magnet30located in each of magnetic steel slots11arranged in the circumferential direction of the rotor core10, two ends of the first permanent magnet20are flush with corresponding two ends of the second permanent magnet30, that is, the first permanent magnet20and the second permanent magnet30have a same size in the circumferential direction of the rotor core10.

In an embodiment, cross sections of each first permanent magnet20and each second permanent magnet30arranged in the circumferential direction of the rotor core10each are in a shape of a rectangle cross section. In this case, the permanent magnet pole40formed by connecting the first permanent magnet20and the second permanent magnet30in series is in a shape of a rectangle. In this case, a shape formed by straight lines connecting centers of the at least three permanent magnet poles40successively is a regular polygon, and the magnetic pole direction of each permanent magnet pole40is in the radial direction of the rotor core10.

In an embodiment, a first central angle θ1 is formed by straight lines connecting the center of the rotor core10and two ends of each permanent magnet pole40, respectively, and the two ends of each permanent magnet pole40are in the circumferential direction of the rotor core10. The first central angle θ1 is greater than π/p and less than 1.5π/p, where p is equal to half of a sum of the number of the permanent magnet poles40and the number of the consequent poles50. In this case, as the magnetic field of the consequent pole50is provided by the magnetic field of the permanent magnet pole40, the first central angle θ1 of the permanent magnet pole40may be guaranteed to be greater than a second central angle θ2 of the consequent pole50. Where the second central angle is formed by straight lines connecting the center of the rotor core10and two ends of each consequent pole50respectively, and the two ends of each consequent pole50are in the circumferential direction of the rotor core10. Thus the magnetic flux density inside the permanent magnet motor can be guaranteed, and the second central angle θ2 of the consequent pole50is also guaranteed to be not too small.

In an embodiment, the coercivity of the first permanent magnet20is less than that of the second permanent magnet30. The first permanent magnet20is located on one side farther away from the center of the rotor core10in the radial direction of the rotor core10than the second permanent magnet30is. That is, the first permanent magnet20with the relatively lower coercivity is located on an outer side (one side proximate to the stator) of the second permanent magnet30with the relatively higher coercivity. Since a magnetism-regulating magnetic field is generated by the stator, when the first permanent magnet20is arranged on the outer side the second permanent magnet30, the magnetism-regulating magnetic field may directly act on the first permanent magnet20, which reduces the difficulty of regulating the magnetism, compared with the situation where the second permanent magnets30with the relatively higher coercivity is arranged on an outer side of the first permanent magnets20with the relatively lower coercivity (in this case, the magnetism-regulating magnetic field first acts on the second permanent magnets30and then on the first permanent magnets20, and when acting on the second permanent magnets30, the magnetic field loses).

Further, in order to ensure that the magnetizing current of the first permanent magnet20with the low coercivity is small, and that the permanent magnet motor may not produce demagnetization during a normal operation, a width of the first permanent magnet20is set to be greater than that of the second permanent magnet30, and the dimensions of the first permanent magnet20and the dimensions the second permanent magnet30satisfy the following relational expression:
50 A/m<(H1×d1+H2×d2)/(d1+d2)<400 A/m;
where d1 denotes the width of the second permanent magnet30with the high coercivity, d2 denotes the width of the first permanent magnet20with the low coercivity, H1 denotes the coercivity of the second permanent magnet30with the high coercivity, and H2 denotes the coercivity of the first permanent magnet20with the low coercivity.

Referring toFIG.3, in another embodiment, cross sections of each first permanent magnet20and each second permanent magnet30arranged in the circumferential direction of the rotor core10may not be rectangular. For example, the cross section of each first permanent magnet20and the cross section of each second permanent magnet30are configured to be V-shaped, and the V-shaped cross sections each have an opening that opens outwards from the center of the rotor core10. That is, each first permanent magnet20includes two parts angled relative to each other, and each second permanent magnet30includes two parts angled relative to each other. In this case, the permanent magnet pole40formed by the first permanent magnet20and the second permanent magnet30is V-shaped, which ensures that the magnetic flux density and the torque density of the permanent magnet motor are improved without changing the first central angle θ1 of the permanent magnet pole40according to the above embodiments.

In an embodiment, a magnetic isolation slot12is provided on the axial end face of the rotor core10, and the magnetic isolation slot12extends in the circumferential direction of the rotor core10starting from two ends of the permanent magnet poles40. The arrangement of the magnetic isolation slot12prevents the magnetic flux of the permanent magnet pole40from closing at an end thereof and reduces the magnetic leakage of the permanent magnet motor.

An embodiment of the present disclosure further provides a rotor100included in the permanent magnet motor described above.

The rotor100and the permanent magnet motor according to the embodiments of the present disclosure have the following beneficial effects:

1. The permanent magnet pole40is formed by the first permanent magnet20and the second permanent magnet30, which are connected in series in a radial direction of the rotor core10and have different coercivities. When the permanent magnet motor is in a low-speed and large-torque state, the permanent magnet with a low coercivity may be magnetized by a magnetizing current to become saturated, so that the magnetic field intensity inside the permanent magnet motor is enhanced to meet requirements. When the permanent magnet motor runs at a high speed and with a low torque, the magnetization degree of the permanent magnet with the low coercivity is reduced by means of the magnetizing current, so that the magnetic field intensity inside the permanent magnet motor is reduced to meet requirements. In this way, the magnetic field intensity of the permanent magnet motor is adjustable, and the permanent magnet motor balances the efficiency at the high frequency and the efficiency at the low frequency.

2. The permanent magnet pole40and the consequent pole50are alternately arranged in the circumferential direction of the rotor core10. Since no permanent magnet is arranged at the consequent pole50, the difficulty of magnetizing the permanent magnet with the low coercivity is reduced. Moreover, the number of permanent magnets is greatly reduced due to the existence of the consequent pole50.

3. In a radial direction of the rotor core10, the first permanent magnet20with the low coercivity is located on an outer side of the second permanent magnet30with a high coercivity, and thus when magnetism needs to be regulated, a magnetism-regulating magnetic field generated by the stator acts directly on the first permanent magnet20, which reduces the difficulty of regulating the magnetism.

The features of the above embodiments may be arbitrarily combined. For the sake of brevity, all possible combinations of the features in the above embodiments are not described. However, if there is no contradiction in the combinations of the features, the combinations shall be considered to be within the scope of the specification.