CN113922542A - Outer rotor permanent magnet synchronous motor with built-in arc-shaped magnetic steel - Google Patents

Abstract

The utility model provides an outer rotor PMSM of built-in arc type magnet steel, relates to motor technical field, and this motor includes the frame, and installs inner stator, outer rotor on the frame respectively, the outer rotor embeds there is a plurality of permanent magnet units that the symmetry was laid, permanent magnet unit comprises two curved magnet steel, and two magnet steel symmetries are laid in d axle both sides to two magnet steel lay the shape and be the arc, the thickness of magnet steel is steadilyd decrease from nearly d axle one side towards nearly q axle one side, and the one end of every magnet steel towards the q axle is provided with magnetism isolating groove. The motor provided by the invention has good flux weakening and speed expanding capability.

Description

Outer rotor permanent magnet synchronous motor with built-in arc-shaped magnetic steel

Technical Field

The invention relates to a motor technology, in particular to a technology of an outer rotor permanent magnet synchronous motor with built-in arc magnetic steel.

Background

The air gap diameter of the outer rotor motor is larger than that of the inner rotor motor, so that the output torque and the rotational inertia are larger, the moment fluctuation is smaller, and the motor is suitable for application in low-speed, large-torque and direct-drive occasions.

As shown in fig. 2, the existing outer rotor motors are all surface-mounted permanent magnet synchronous motors (SPMSM), which mainly comprise an inner stator 72 and an annular outer rotor 71, the inner stator is located in the annular hole of the outer rotor, the inner stator and the outer rotor are in clearance fit, and surface-mounted tile-shaped magnetic steels 73 protruding radially inwards are uniformly distributed on the inner annular surface of the outer rotor 71, because the magnetic permeability of the permanent magnet is close to air, the alternating and direct axial air gaps are uniform, the alternating and direct axial inductances are equal (Ld = Lq), the surface-mounted outer rotor permanent magnet synchronous motors belong to a non-salient magnetic circuit, do not generate reluctance torque, and because the equivalent air gap is large, the problem of weak magnetic expansion is difficult to solve, a very large direct axial current must be introduced into the stator winding to achieve the purpose of weak magnetic expansion, the method can reduce torque, increase stator loss, reduce the efficiency of the driving system, and possibly cause the risk of irreversible demagnetization of the permanent magnet, the poor flux weakening speed expansion capability is the root cause for hindering the development of the SPMSM.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to solve the technical problem of providing the outer rotor permanent magnet synchronous motor with built-in arc-shaped magnetic steel and good flux weakening and speed expanding capability.

In order to solve the technical problem, the outer rotor permanent magnet synchronous motor with built-in arc magnetic steel provided by the invention comprises a base, an inner stator and an annular outer rotor, wherein the outer rotor is rotatably arranged on the base, the inner stator is fixed on the base and is positioned in an annular hole of the outer rotor, and the inner stator and the outer rotor are in clearance fit, and the outer rotor permanent magnet synchronous motor is characterized in that: a plurality of permanent magnet units are arranged in the outer rotor, and are symmetrically distributed around a rotating shaft of the outer rotor;

the permanent magnet unit is composed of two arc-shaped magnetic steels, the two magnetic steels are symmetrically arranged on two sides of the d axis, the arrangement shapes of the two magnetic steels are arc-shaped, the thickness of the magnetic steels is gradually reduced from one side close to the d axis to one side close to the q axis, and one end, facing the q axis, of each magnetic steel is provided with a magnetism isolating groove.

The outer rotor of the outer rotor permanent magnet synchronous motor with the built-in arc magnetic steel adopts a salient pole structure, and the arc magnetic steel group is built in the outer rotor, so that the quadrature axis inductance is larger than the direct axis inductance, the salient pole effect is achieved, the motor is superposed with the reluctance torque on the basis of the permanent magnet torque, the reluctance torque is beneficial to flux weakening and speed expansion, the outer rotor permanent magnet synchronous motor has the characteristic of good flux weakening and speed expansion capacity, the starting characteristic, the overload capacity and the power density of the motor can be improved, and the constant power range operation is expanded.

Drawings

FIG. 1 is a schematic radial cross-sectional view of a rotor of an outer rotor permanent magnet synchronous motor with built-in arc magnetic steel according to an embodiment of the present invention;

fig. 2 is a schematic radial cross-sectional view of a stator and a rotor of a conventional surface-mounted outer rotor permanent magnet synchronous motor.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to the following description of the drawings, but the embodiments are not intended to limit the present invention, and all similar structures and similar variations using the present invention shall be included in the scope of the present invention, and the pause numbers in the present invention shall have a relation of the same.

As shown in fig. 1, an outer rotor permanent magnet synchronous motor with built-in arc magnetic steel provided in an embodiment of the present invention includes a machine base (not shown), an inner stator (not shown), and an annular outer rotor 1, wherein the outer rotor 1 is rotatably mounted on the machine base, the inner stator is fixed on the machine base and is located in an annular hole of the outer rotor, and the inner stator and the outer rotor are in clearance fit, and the outer rotor permanent magnet synchronous motor is characterized in that: a plurality of permanent magnet units are arranged in the outer rotor 1, and are symmetrically distributed around a rotating shaft of the outer rotor;

the permanent magnet unit is composed of two arc-shaped magnetic steels 2 and forms a permanent magnet pole with a pole shoe 4, the two magnetic steels 2 are symmetrically arranged on two sides of a d axis, the arrangement shape of the two magnetic steels 2 is arc-shaped, the thickness of the magnetic steel 2 decreases gradually from one side close to the d axis (magnetic pole center line) to one side close to a q axis (interelectrode center line), so that the magnetic density decreases gradually from the magnetic pole center to two ends, the air gap magnetic density waveform between a stator and a rotor can be improved, torque fluctuation can be effectively inhibited, mechanical vibration, noise and counter potential harmonic waves are reduced, the motor can run stably, one end of each magnetic steel 2 facing the q axis is provided with a magnetic isolation groove 3, and the q axis radial force of the d axis of the magnetic pole radial center line and the q axis of the interelectrode center line tends to be balanced.

The embodiment of the invention is suitable for the power motor of the electric automobile and can operate in the speed regulation range of low-speed constant torque and high-speed constant power.

In the embodiment of the invention, the quadrature axis inductance is greater than the direct axis inductance (Lq is greater than Ld), the salient pole effect is realized, the salient pole ratio (Lq/Ld) is greater than 1, so that the motor is superimposed with reluctance torque on the basis of permanent magnet torque, the reluctance torque is beneficial to flux weakening and speed expansion, the starting characteristic, overload capacity and power density of the motor are improved, the constant power range operation is expanded, and the magnetic isolation grooves arranged at the two ends of the magnetic steel can form air magnetic flux barriers (magnetic barriers), so that the effects of good magnetic isolation and magnetic flux leakage inhibition can be realized. In the conventional outer rotor surface-mounted permanent magnet synchronous motor (SPMSM), the quadrature axis inductance is equal to the direct axis inductance (Ld = Lq), and reluctance torque is not generated, so that flux weakening and speed expansion are difficult to solve.

The magnetic conducting bridge is formed in the area, located between the adjacent ends of the two magnetic steels, on the outer rotor, and is in a magnetic path saturation state to the permanent magnetic flux when the magnetic conducting bridge is in no-load state, so that the permanent magnetic flux is difficult to pass through the magnetic conducting bridge, and when a motor is loaded, under the action of stator current, armature reaction is demagnetized, so that a part of the permanent magnetic flux flows to the magnetic conducting bridge between the magnetic steels to form leakage flux, and the density of the magnetic flux passing through an air gap is reduced. The magnetic circuit saturation degree of the magnetic conduction bridge can be adjusted by adjusting the width of the magnetic conduction bridge, so that the permanent magnetic flux (forming leakage flux) of the magnetic conduction bridge in the way is adjusted and controlled, and the reduction degree of the air gap flux density is adjusted and controlled. Because the magnetic conduction bridge can play a key role in regulating and controlling leakage magnetic flux along with load change, a wider constant-power speed range than that of the existing surface-mounted permanent magnet motor can be obtained, and high power density, wide speed regulation, fast response, frequent starting and stable operation can be realized. On one hand, the magnetic circuit saturation can be adjusted, the leakage flux can be adjusted, an additional flux path is provided, the constant power speed expansion capability of a high-speed area of the motor is improved, on the other hand, the magnetic circuit saturation adjusting device is equivalent to a reinforcing rib of a rotor, can resist high-speed centrifugal force, improves overload capability, and is beneficial to frequent starting of the motor.

Claims (1)

1. The utility model provides an outer rotor PMSM of built-in arc type magnet steel, includes frame, inner stator, and annular outer rotor, the outer rotor is installed on the frame with rotatable mode, the inner stator is fixed on the frame to the inner stator is located the annular ring of outer rotor, and inner stator and outer rotor are clearance fit, its characterized in that: a plurality of permanent magnet units are arranged in the outer rotor, and are symmetrically distributed around a rotating shaft of the outer rotor;

the permanent magnet unit is composed of two arc-shaped magnetic steels, the two magnetic steels are symmetrically arranged on two sides of the d axis, the arrangement shapes of the two magnetic steels are arc-shaped, the thickness of the magnetic steels is gradually reduced from one side close to the d axis to one side close to the q axis, and one end, facing the q axis, of each magnetic steel is provided with a magnetism isolating groove.

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