BG4089U1 - Brushless electrical machine with permanent magnetic excitation - Google Patents

Abstract

The brushless machine is designed for electrical drives, in particular, for boats, pumps, electric vehicles, such as for work as a servomotor, etc. The brushless electrical machine provides increased power with significantly reduced weight and moment of inertia of its rotor. The rotor (11) consists of outer (12), intermediate (13) and inner (14) steel rings. The surface of the rotor poles (11) is formed by interconnected segment parts (15). In the rotor (11), above the permanent magnets (17) are formed elongated second axial ducts (20). With the number of poles 2pq that is less than sixteen and with the diameter of the rotor (11) that is greater than 0.15 m, the first axial ducts (16) are divided into two equal parts by a third radial rib (25) with a maximum width of 0,0025 m, which is located below the middle of the segment part (15) and is connecting the intermediate ring (13) to the outer ring (12).

Description

Field of technology

The utility model refers to a brushless electric machine with excitation by permanent magnets, designed to drive, in particular, boats, pumps, electric vehicles, to work as a servomotor and others.

BACKGROUND OF THE INVENTION

A brushless electric machine with permanent magnet excitation [1] is known for driving electric vehicles, comprising a shaft mounted in front and rear shields by means of front and rear bearings. The front and rear shields cover the stator. containing a stator package fixed by a housing. Numerous evenly distributed channels are located on the inner surface of the stator package, in which a three-phase winding is placed. The stator movably encloses an annular rotor fixed to the shaft. At least two poles of permanent magnets are formed in the rotor, which are inserted into the first axial channels located near its outer surface. The permanent magnets are located in the rotor in one or more layers. In the vicinity of the permanent magnets and the outer surface of the rotor, a number of second axial channels are formed, influencing the magnetic flux between the rotor and the stator. The second axial channels are located on both sides of the permanent magnets. The grooves are separated from the outer surface of the rotor by thin strips.

A problem with this famous electric machine is its reduced power with increased weight and moment of inertia of its rotor.

The reduced power is due to the fact that in the realization of the electric machine with one layer of permanent magnets, the third harmonic component of the magnetic field in the air gap has an increased value, which increases the losses in the stator iron. Another reason for this is that when connecting the phases in a triangle, the electrical losses from the third harmonic component of the current are also increased.

The increased value of the inductive resistance is due to the increased value of the transverse magnetic flux created by the stator winding. This is the reason for the increased value of current and electrical losses, especially when working in the first zone, which is characterized by a constant moment.

When the known machine is realized with reduced width of permanent magnets and more than one layer of magnets, the problem is the increased mass of magnets due to the distance of the working area of the magnets from the point of characteristic at which the energy is maximum.

Technical essence of the utility model

The task of the utility model is to create a brushless electric machine with excitation from permanent magnets with increased power with a significant reduction in the weight and moment of inertia of its rotor.

This problem is solved by a brushless electric machine with excitation by permanent magnets, comprising a shaft mounted in front and rear shields by means of front and rear bearings, the front and rear shields comprising a stator containing a stator package covered by a housing. On the inner surface of the stator package are located many evenly distributed channels in which is laid three-phase 2

BG 4089 UI winding. The stator movably encloses an annular rotor fixed to the shaft. At least two poles of permanent magnets are formed in the rotor, inserted into the first axial grooves located near its outer surface. At least two second axial channels are formed near the permanent magnets and on the outer surface of the rotor, influencing the magnetic flux between the rotor and the stator. According to the utility model, the annular rotor comprises an outer steel ring, an intermediate steel ring and an inner steel ring. The outer steel ring comprises interconnected cutting parts, each of which is shaped as part of a steel cylinder cut in a plane containing the chord from the cross section of the cylinder. The axis of the cylindrical surface of each pole does not coincide with the axis of the shaft. The second axial channels, influencing the magnetic flux between the rotor and the stator, are formed in the cutting parts, are parallel to the axis of the rotor and extend along its entire length. Every second axial channel has two flat opposite walls oriented radially with respect to the rotor axis.

The two ends of the flat opposite walls of each second axial channel, which are close to the permanent magnet and the outer surface of the rotor, respectively, are connected to each other by respective parts of cylindrical surfaces whose convex parts are directed to the permanent magnet and the outer rotor surface. The most convex part of each cylindrical surface is less than 0,0025 m from the permanent magnet and the outer surface of the rotor, respectively, and the greatest distance a between the opposite flat walls of every second axial channel is less than 0 The distance β between the most convex parts of the opposite cylindrical surfaces of every second axial channel is variable and decreases in the direction from the middle of the cutting part to its two ends. Under the flat wall of each cut-out part is formed the first axial channel in which the permanent magnet is inserted. The outer surface of the cutting part is the pole of the rotor and has three characteristic points, one of which is in the middle of the pole, at a distance of 61 from the inner surface of the stator, and the other two points are symmetrical to it at a distance of one third of the pole and are spaced from the inner surface of the stator at a distance of 62, where b 1 <62 <2,661. The intermediate steel ring includes rectangular prismatic parts with a maximum radial size of 0.6 Da / p. Each of the quadrangular prismatic parts belongs to two adjacent poles of the rotor. The quadrangular prismatic parts are connected to each other by second strips, which are located below the middle of the poles. The outer steel ring encloses the intermediate steel ring and is connected to it by first radial ribs located at the boundaries between the poles. The cutting parts in the area between the permanent magnets and the first radial ribs are formed as first strips with a maximum radial size of 0.0006 t. The intermediate steel ring is connected to the inner steel ring by second radial ribs located below the quadrangular prismatic parts. Between the intermediate steel ring, the inner steel ring and the connecting second radial ribs, a plurality of identical in shape and size holes are formed at equal distances from each other.

Preferably, the minimum tangential size of the first radial ribs is less than 0.0025 t.

Preferably, the second strips have a maximum radial size of 0.003 m and a maximum tangential size of 0.006 m.

Preferably, the second radial ribs have a tangential size of less than 0.005 m.

BG 4089 UI

With a number of poles 2p less than sixteen and a rotor diameter greater than 0.15 t, the axial grooves are divided into two equal parts by a third radial rib with a maximum width of 0.0025 t, which is located below the middle of the the cutting part and is connecting the intermediate ring with the outer ring, and in each divided axial channel is placed a corresponding permanent magnet.

An advantage of the brushless electric machine with excitation by permanent magnets, according to the utility model is that there is increased power of the electric machine, which is due to the fact that the third harmonic component in the field of magnetic induction above the poles is reduced. when connected in a triangle, the third harmonic component of the current in the phases is reduced due to the eccentricity of the pole surface relative to the inner diameter of the stator. which leads to reduced losses in the stator iron and to electrical losses from the third harmonic current in the phases when connected in a triangle, hence to increased power.

Another reason for ensuring the increased power of the electric machine is the reduction of the transverse magnetic field created by the stator winding due to the presence of groups of channels in the sections, resulting in reduced inductive resistance of the stator winding, current value and electrical losses.

Another advantage of the electric machine, according to the utility model, is the increased resistance to demagnetization of the permanent magnets from the field of the stator winding due to the increased magnetic resistance in the intermediate ring due to the narrowing realized under the permanent magnets.

Another advantage is the reduced weight and moment of inertia of the rotor due to the presence of constrictions in the intermediate ring and the separation of the inner from the intermediate ring by means of the second ribs. The area of action of the permanent magnets is closer to the area of maximum energy due to the increased width of the permanent magnets.

Explanation of the attached figures

The brushless electric machine with excitation by permanent magnets, according to the utility model, is illustrated by means of several exemplary embodiments shown in the attached figures, where:

Figure 1 is a longitudinal half-section in the middle of a permanent magnet of a first embodiment of the utility model, realized with whole magnets of a brushless electric machine;

Figure 2 is a cross-sectional half-section of the rotor and stator of a brushless electric machine of the first embodiment of the utility model;

Figure 3 is a longitudinal half-section in the middle of the pole of a brushless electric machine of a second embodiment of the utility model, realized with permanent magnets divided into two parts by means of ribs;

Figure 4 is a cross-sectional half-section of the rotor and stator of a brushless electric machine, realized by a second embodiment of the utility model, in which the permanent magnets are divided into two parts by means of ribs;

Figure 5 is an enlarged partial sectional view showing the connection of two adjacent cut-off parts in the region between two adjacent permanent magnets.

BG 4089 UI

Examples of implementation of the utility model

Figure 1, Figure 2 and Figure 5 show a first embodiment of the utility model, comprising a shaft 1 mounted in a front panel 2 and a rear panel 3 by means of a front bearing 4 and a rear bearing 5. The front panel 2 and the rear panel 3 comprise stator 6 with inner diameter Da. The stator 6 comprises a stator package 7 fixedly enclosed by a housing 8. A plurality of evenly distributed channels 9 are formed on the inner surface of the stator package 7. An insulated coil 10 is placed in each channel 9. comprises an outer steel ring 12, an intermediate steel ring 13 and an inner steel ring 14. The outer steel ring 12 comprises interconnected cutting parts 15. Each cutting part 15 is formed as part of a steel cylinder cut in a plane containing the chord from the transverse section of the cylinder, and the axis of the cylindrical surface of each pole does not coincide with the axis of the shaft 1. In the annular rotor 11, under the flat wall of each cutting part 15 is formed a first axial channel 16 located on the chord. in which a permanent magnet 17 in the shape of a parallelepiped is inserted. The outer surface of the cutting parts 15 is the pole of the rotor 11 and has three characteristic points. One of the characteristic points is located in the middle of the pole and is at a distance of 61 from the inner surface of the stator package 7. The other two characteristic points are symmetrical in the middle of the pole and are located at distances equal to one third of the pole division. at a distance 62 from the inner surface of the stator package 7, where the condition 61 <62 <2,661 is met.

As shown in Figure 2, the outer steel ring 12 encloses the intermediate steel ring 13 and is connected to it by first radial ribs 18 with a minimum tangential size of less than 0.0025 t. The first radial ribs 18 are located at the boundaries between the poles of the the rotor 11. The cutting parts 15 in the area between the permanent magnets 17 and the first ribs 18 have formed first strips 19 with a maximum radial size of 0.0006 m (Fig. 5).

At each pole of the rotor 11, below the flat wall of the cutting parts 15, the first axial grooves 16 located along the chord are surrounded laterally by the first radial ribs 18. Every two adjacent cutting parts 15 are connected by first strips 19. In each cutting part 15, six second axial channels 20 are formed in the area above the permanent magnet 17 and the outer surface of the rotor 11, influencing the magnetic flux between the rotor 11 and the stator 6. The second axial channels 20 are parallel to the axis of the rotor 11 and extend along its entire length. Each second axial channel 20 has two flat opposing walls oriented radially with respect to the rotor axis 11. The two ends of the flat opposing walls of each second axial channel 20 which are close to the permanent magnet 17 and the outer surface of the rotor 1 1 respectively, are interconnected by respective parts of cylindrical surfaces. The convex parts of the cylindrical surfaces are located in the direction of the permanent magnet 17 or the outer surface of the rotor 11. The most convex parts of each cylindrical surface are spaced from the permanent magnet 17 and the outer surface of the rotor 11, respectively. of 0.0025 t. The opposite flat walls of each second axial channel 20 are located so that the greatest distance a between them is less than 0.0025 t. The distance β between the most convex parts of the opposite cylindrical surfaces of each second axial channel 20 is different and decreases in the direction of the two lateral first strips 19 surrounding the respective cutting part 15. The intermediate steel ring 13 includes quadrangular prismatic parts 21 with a maximum radial size of 0.6 Da / p. Each quadrangular

BG 4089 UI prismatic part 21 belongs to two adjacent poles of the rotor 11 and has an axis that is parallel to the axis of the stator 6. The quadrilateral prismatic parts 21 are connected by second strips 22, which are located below the middle of the poles and are with maximum radial size 0.003 m and maximum tangential size 0.006 t. The intermediate steel ring 13 is connected to the inner steel ring 14 by second radial ribs 23 with maximum tangential size 0.005 t, which are located below the quadrangular prismatic parts 21. Between the intermediate steel ring 13, the inner steel ring 14 and the connecting second radial ribs 23 are formed by a plurality of identical in shape and size openings 24 spaced at equal distances from each other.

Figure 3. Figure 4 and Figure 5 show a second embodiment of the utility model, which is applicable when the number of poles 2p is less than 16 and with a rotor diameter 11 greater than 0.15 t. differs from the first embodiment in that the first axial channels 16 located along the chord are divided into two equal parts by a third radial rib 25 with a maximum width of 0.0025 t, which is located below the middle of the cutting part 15 and connects the intermediate ring 13 with the outer ring 12. In each divided first axial channel 16 a corresponding permanent magnet 17 is inserted.

It is possible that the exemplary embodiments described above can be implemented without a housing 8.

It is possible to connect a control sensor to the brushless electric machine, according to the utility model 26.

Utility action

A permanent magnetic flux is created from the permanent magnets 17, which closes between the adjacent poles and passes through the air gap between the rotor 11 and the stator 6. When a controlled three-phase voltage is applied to the stator winding 10. a torque is generated which, when the annular rotor 11 rotates, generates a corresponding power.

Through the eccentric air gap, the permanent magnets 17 in the rotor 11 of the brushless electric machine create a magnetic field in the air gap above each pole with the highest value of magnetic induction in the middle of the pole and decreasing values of magnetic induction at the pole ends. Thus, in a layer of permanent magnets 17 in the air gap, the third harmonic component of the magnetic field is reduced. Through the second axial channels 20 in the cutting parts 15 in the outer steel ring 12 of the rotor 11, when the electric machine is running, the inductive resistance is reduced and the current value is reduced without causing a reduction in power. As a result, during the operation of the electric machine the iron and main losses are reduced, and when its phases are connected in a triangle, the additional electric losses are reduced. As a result, power is increased.

Experimental data in the study of an experimental sample realizing the utility model

A physical sample that was made without any improvements according to the utility model was experimentally examined and it was compared with a physical sample that was made according to the utility model. The design parameters of the two samples are: outer diameter of the stator 0.18 t; inner diameter of the stator 0.14 t; stator package length 0.05 t; 2p = 12; number of channels Z = 72; connecting the windings in a triangle. Nominal parameters: power 5 kW; rotation speed 5000 min - 1; voltage of

EN 4089 UI battery 48 V. By measuring the useful power, which is carried out by measuring the speed and torque, an increase in the efficiency of the sample made according to the utility model, compared to the sample that is not built according to the useful model, from 89.8% to 93.7%, ie the power is increased by more than 0.2 kW and the weight of the steel is reduced by about 30%, with a moment of inertia reduced by 20%.

Claims (1)

Brushless electric machine with permanent magnet excitation, comprising a shaft mounted in front and rear shields by means of front and rear bearings, the front and rear shields comprising a stator containing a stator package covered by a housing, and on the inner surface of the stator package a plurality of uniformly distributed channels in which a three-phase winding is applied, the stator movably enclosing an annular rotor fixedly mounted on the shaft, the rotor forming at least two poles of permanent magnets inserted in first axial channels located near its outer a surface in which at least two second axial channels are formed in the vicinity of the permanent magnets and the outer surface of the rotor, influencing the magnetic flux between the rotor and the stator, characterized in that the annular rotor (11) comprises an outer steel ring (12) , an intermediate steel ring (13) and an inner steel ring (14), wherein the outer steel ring (12) with holds sequentially interconnected cutting parts (15), each of which is formed as part of a steel cylinder, cut in a plane containing the chord of the cross section of the cylinder, and the axis of the cylindrical surface of each pole does not coincide with the axis of the shaft (1 ), wherein the second axial channels (20) influencing the magnetic flux between the rotor (11) and the stator (6) are formed in the cutting parts (15), are parallel to the axis of the rotor (11) and extend along its entire length, each second axial channel (20) having two flat opposite walls oriented radially with respect to the rotor axis (11) and the two ends of the flat opposite walls of each second axial channel (20) which are close to the permanent magnet ( 17) and, respectively, to the outer surface of the rotor (11), are connected to each other by respective parts of cylindrical surfaces, the convex parts of which are directed, respectively, to the permanent magnet (17) and the outer surface of the rotor (11). -the convex part of the whole The cylindrical surface is less than 0,0025 m from the permanent magnet (17) and the outer surface of the rotor (11), respectively, and the greatest distance is alpha between the opposite flat walls of each second axial channel (20). is less than 0,0025 m, the distance beta between the most convex parts of the opposite cylindrical surfaces of each second axial channel (20) being variable and decreasing in the direction from the middle of the cutting part (15) to its two ends , and under the flat wall of each cutting part (15) is formed the first axial channel (16), in which the permanent magnet (17) is inserted, where the outer surface of the cutting part (15) is the pole of the rotor (11) and has three characteristic points, one of which is in the middle of the pole, spaced b1 from the inner surface of the stator (6), and the other two points are located symmetrically to it at distances of one third of the pole division and are spaced from the inner surface of the stator (6) at a distance we b2, where b1 <b2 <2,6b1, and the intermediate steel ring (13) includes quadrangular prismatic parts (21) with a maximum radial size of 0.6 Da / p, each of the quadrangular prismatic parts (21) belonging to two adjacent poles of the rotor (11), wherein the quadrangular prismatic parts (21) are connected to each other by second strips (22), which are located below the middle of the poles, and the outer steel ring (12) encloses the intermediate steel ring (13) and is connected to it by first radial ribs (18) located at the boundaries between the poles, wherein the cutting parts (15) in the area between the centers of the quadrangular prismatic parts (21) and between the intermediate steel ring (13), the inner steel ring 14) and the connecting second radial ribs (23) are formed by a plurality of identical in shape and size openings (24) spaced at equal distances from each other.