CN116155008A

CN116155008A - Limit environment natural magnetic suspension switch reluctance energy storage flywheel motor

Info

Publication number: CN116155008A
Application number: CN202310255517.4A
Authority: CN
Inventors: 杨贵杰; 赵辉; 苏健勇; 李铁才
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2023-03-16
Filing date: 2023-03-16
Publication date: 2023-05-23

Abstract

A natural magnetic suspension switch reluctance energy storage flywheel motor in a limit environment relates to the field of motors. The invention aims to solve the problems of large volume and great control difficulty of the magnetic suspension motor of the energy storage system used in the existing limit environment. The invention relates to a limit environment natural magnetic suspension switch reluctance energy storage flywheel motor, which comprises a rotating shaft, a stator and a rotor which are coaxially arranged, wherein the stator comprises three sections which are coaxially and axially arranged, each section comprises a stator iron core and a stator winding, an even number of stator grooves are formed in the stator iron core, 2 wire rods are arranged in each stator groove, two wire rods in one stator groove are respectively connected with one wire rod in two adjacent grooves in series to respectively form two branches, all the branches are uniformly arranged along the circumferential direction of the stator iron core, one ends of all the branches are mutually connected in parallel to form one phase of a three-phase winding, and the other ends of all the branches are mutually connected in parallel to be used as midpoints of the three-phase winding.

Description

Limit environment natural magnetic suspension switch reluctance energy storage flywheel motor

Technical Field

The invention belongs to the field of motors.

Background

The flywheel energy storage system stores energy through a flywheel rotating at a high speed, and realizes the cyclic conversion of electric energy and kinetic energy. It is a purely physical energy storage mode. The latest technical development direction of the flywheel energy storage system is to adopt a magnetic suspension technology, in the flywheel energy storage system, a shafting is an important device for power transmission and is also a main part of flywheel energy self-loss, so that the stability, efficiency and service life of the flywheel system are affected.

The extreme environment also requires a flywheel energy storage system. For example: space-consuming motors, which require high rotational speeds at low temperatures, lead to short mechanical bearing life, and therefore require motors with levitation capability. The temperature difference between the day and night on the surface of the moon is extremely large and can reach minus 180 ℃ to +150 ℃. A servo drive assembly is needed that can operate directly in this extreme environment. For example: power generation systems and energy storage systems used in space-limited environments, and the like. Similarly, the earth also has limited environments, such as: nuclear radioactive environments, extreme temperature differential environments, sudden hazardous environments, and the like. The key points of breaking through the limit temperature difference environment are as follows: the traditional bearing adopts a negative gap to improve the precision, and the expansion and contraction of the mechanical bearing inevitably causes the damage, the seizing or the abrasion of the bearing gap. Therefore, a bearingless design is chosen to address this difficulty. However, the cost of suspending the motor rotor is very high, in general, in a magnetic suspension motor, the volume of the magnetic suspension bearing accounts for 60%, and the cost of a controller of the magnetic suspension bearing is high and complex.

Disclosure of Invention

The invention aims to solve the problems of large volume and great control difficulty of an energy storage system magnetic suspension motor used in the existing limit environment, and provides a natural magnetic suspension switch reluctance energy storage flywheel motor in the limit environment.

The utility model provides a limit environment natural magnetic suspension switch magnetic resistance energy storage flywheel motor, including coaxial pivot, stator and the rotor that sets up, the stator includes coaxial and along the three sections of axial arrangement, every section includes stator core and stator winding, it has even number stator groove to open on the stator core, there are 2 bars in every stator inslot, two bars in a stator groove establish ties respectively with a bar in the adjacent inslot in both sides respectively and constitute two branch road, all branch roads are evenly arranged along stator core circumference, one end of all branch roads is parallelly connected each other and is constituted three-phase winding's a phase, the other end of all branch roads is parallelly connected each other and is regarded as three-phase winding's midpoint.

Furthermore, the limit environment natural magnetic suspension switch reluctance energy storage flywheel motor further comprises a shell, wherein the shell is of a vacuum cavity structure, and the rotating shaft, the stator and the rotor are all positioned in the vacuum cavity of the shell.

Further, two ends of the rotating shaft are respectively connected with the shell through bearings.

Further, the bearing clearance of the bearing is 0.1mm to 0.5mm.

Further, a gasket is arranged between the bearing and the shell.

Further, an electrical interface is provided on the housing.

Further, the stator is coaxially sleeved outside the rotor, or the rotor is coaxially sleeved outside the stator.

The beneficial effects of the invention are as follows:

(1) The motor has simple and firm structure and simple manufacturing process. The cost is low, and the rotor is formed by laminating silicon steel sheets only and can work at extremely high rotating speed; the stator coil is a concentrated winding, is easy to embed, has short and firm end parts, works reliably, and can be suitable for various severe and high Wen Ji to strong vibration environments.

(2) Losses mainly occur in the stator, and the motor is easy to cool; the rotor has no permanent magnets, allowing a higher temperature rise.

(3) The torque direction is irrelevant to the phase current direction, so that the number of switching devices of the power converter can be reduced, and the system cost is reduced.

(4) And the power converter cannot have through faults, and the reliability is high.

(5) The starting torque is large, the low-speed performance is good, and the phenomenon of impact current generated when the asynchronous motor is started is avoided.

(6) The speed regulating range is wide, the control is flexible, and various torque-speed characteristics required by special requirements are easy to realize.

(7) High efficiency over a wide range of speeds and powers.

(8) And the four-quadrant operation can be realized, and the regenerative braking capability is high.

In conclusion, the invention breaks through the application problem of the extreme temperature difference environment, and eliminates the problem of bearing clearance damage, seizing or abrasion caused by thermal expansion and cold contraction of the mechanical bearing in the extreme environment. The invention can be used in large mechanical equipment in a space limit environment, in particular to an energy storage flywheel system in the space limit environment. Can also be used in earth-limited environments such as: nuclear radioactive environments, extreme temperature differential environments, sudden hazardous environments, and the like.

Drawings

FIG. 1 is a schematic diagram of a switched reluctance motor of an inner rotor;

FIG. 2 is a schematic diagram of an outer rotor switched reluctance motor;

FIG. 3 is a magnetic field simulation diagram of a conventional switched reluctance motor, wherein (a) shows that the teeth of the stator and the rotor are aligned with the slots, and (b) shows that the teeth of the stator and the rotor are staggered with the slots;

FIG. 4 is a magnetic field simulation of a switched reluctance motor of the present invention wherein (a) indicates that the teeth of the stator and rotor are aligned with the slots and (b) indicates that the teeth of the stator and rotor are offset from the slots;

FIG. 5 is a graph of the inductance change rate of a switched reluctance motor;

FIG. 6 is a schematic diagram of a connection structure of stator windings;

FIG. 7 is a radial cross-sectional view of a switched reluctance motor;

fig. 8 is an axial cross-sectional view of a switched reluctance motor.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.

The first embodiment is as follows: referring to fig. 1 to 8, a description is specifically given of the present embodiment, and the limit environment natural magnetic suspension switched reluctance energy storage flywheel motor according to the present embodiment includes a rotating shaft, a stator, a rotor 3, and a housing 5 coaxially disposed.

The shell 5 is of a vacuum cavity structure, and the rotating shaft, the stator and the rotor 3 are all positioned in a vacuum cavity 6 of the shell 5. The natural magnetic suspension flywheel motor is surrounded by an outer vacuum cavity, the vacuum cavity is positioned outside the flywheel motor, and the flywheel motor is sealed in the vacuum cavity. The flywheel motor is an inner rotor flywheel motor, and the flywheel rotor of the flywheel motor can provide momentum. The two ends of the rotating shaft are respectively connected with the shell 5 through bearings 4. The housing 5 is provided with an electrical interface 8. A washer 7 is arranged between the bearing 4 and the housing 5.

The bearing clearance of the bearing 4 is 0.1-0.5 mm, and the problem that the bearing clearance is damaged, blocked or worn due to expansion and contraction of heat and cold of the additional bearing 4 in a limit environment can be effectively solved. The embodiment can be used in large mechanical equipment in a space limit environment, and the working temperature of a motor is +/-180 ℃. The stator comprises three sections which are coaxial and are axially arranged, each phase of winding is provided with a section of iron core, and the winding method of the windings is consistent. Specifically, each segment includes a stator core 1 and a stator winding 2. The stator core 1 is provided with 16 stator slots, and each phase of winding can generate restoring force to radial offset of the motor from 16 directions. Therefore, each phase of winding can form windings which are distributed symmetrically along the circumference center, and can generate center symmetrical couple moment, and three sections of stator cores are mutually staggered by 120 degrees of electric angles. The specific circuit structure is as follows: each stator slot is internally provided with 2 wire rods, two wire rods in one stator slot are respectively connected with one wire rod in two adjacent slots at two sides in series to respectively form two branches, all the branches are uniformly distributed along the circumferential direction of the stator core 1, one ends of all the branches are mutually connected in parallel to form one phase of a three-phase winding, and the other ends of all the branches are mutually connected in parallel to form the midpoint of the three-phase winding.

In this embodiment, the stator is divided into three axial segments, each of which is a UVW three-phase flywheel motor. As shown in fig. 6, wherein: 1. 3, 5, 7, 9, 11, 13 and 15 slot winding ports are connected in parallel to form respective three-phase winding ports of U, V, W. Wherein: 2. 4, 6, 8, 10, 12, 14, 16 slot winding ports are connected in parallel to form a midpoint port O of each three-phase winding of U, V, W respectively. Each phase of independent windings of the U, V, W three-phase windings is provided with 8 pairs of windings which are distributed in a mirror symmetry way; and connecting the midpoint ports O of the three-phase windings in parallel to finally form the U, V, W three-phase windings.

The attractive force exists between the stator core and the rotor core, the air gap between the stator and the rotor is kept equal due to the effect of the bearing 4, the attractive force is equal everywhere along the circumference, and the radial attractive force in the air gap of the motor is equal everywhere and counteracts each other by the bearing. If the air gaps at the two ends of the same diameter have deviation, the rotor body is sucked to the side with small air gap, and the counter potential (or potential of a transformer) of the parallel branch on the side with small air gap is necessarily increased, and the current is reduced; conversely, the counter potential (or the potential of the transformer) of the parallel branch on the side with the large air gap becomes smaller, the current becomes larger, the radial pulling force on the side with the large air gap becomes larger, the radial pulling force on the side with the small air gap becomes smaller, the air gap is inevitably changed in the direction of decreasing the deviation, and the deviation of the air gap is stabilized. For a switched reluctance motor, even if the motor is in a starting state, the potential of the transformer, namely the induced potential, exists when the motor is not rotated, so the embodiment has complete radial natural magnetic levitation recovery centering capability. Because the switch reluctance motor does not have permanent magnetic interference force, the high-precision natural electromagnetic magnetic suspension is realized more favorably. The additional bearing can be adopted, so that the bearing can adapt to heavy load and all-weather limit environments. Maximum inductance/minimum inductance=21.25 (much larger than conventional), reduced inductance end rate of change, reduced noise, greatly improved motor power density, and performance over permanent magnet motors.

The stator is coaxially sleeved outside the rotor 3, or the rotor 3 is coaxially sleeved outside the stator. Fig. 1 is an inner rotor motor, with an outer stator divided into three sections. Fig. 2 is an external rotor motor, and an internal stator is divided into three sections.

The ratio of the maximum inductance Lmax to the minimum inductance Lmin in this embodiment is as high as 6 to 8, whereas the conventional switched reluctance motor can only reach about 2.5. Because the inductance ratio of the switch reluctance motor is large, the output torque of the motor is large, namely the power density of the motor is large. The principle of the switched reluctance motor not only enables the switched reluctance motor to operate in four quadrants, but also can conveniently realize voltage stabilization adjustment of output voltage in a generator state by adjusting a conduction angle. And the switch reluctance motor has the strongest structure and is an ideal motor of an energy storage flywheel running in a space limit environment.

Compared with the traditional switch reluctance motor, the stator section and the tooth slot ratio of the embodiment are matched, the magnetic path length is greatly shortened,

the moment area is greatly reduced. The motor power density can be greatly improved, and the efficiency is improved. The torque ripple and noise level of this embodiment is comparable to that of a permanent magnet motor and an induction motor. The motor and the driver thereof are simple, and the manufacturing cost can be reduced by more than 30 percent. The stator of the embodiment is provided with the segmented independent windings, so that the number of motor segments is increased by 3 times, the number of turns of each slot of conductor is increased by 3 times, and the magnetic suspension restoring force is greatly increased by 9 times.

The efficiency curve of the switched reluctance motor is in the range of 125-50% of rated rotation speed and in the range of 50-300% of rated torque, the efficiency is not lower than 82%, and the highest efficiency is 92%. When the rotational speed of the permanent magnet brushless motor is reduced to 50% of rated speed, the efficiency is also reduced to 50% or less. The rated current of 30% of the switch reluctance motor can reach 150% of rated torque.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein may be combined in ways other than as described in the original claims. It is also to be understood that features described in connection with separate embodiments may be used in other described embodiments.

Claims

1. A limit environment natural magnetic suspension switch reluctance energy storage flywheel motor, which comprises a rotating shaft, a stator and a rotor (3) which are coaxially arranged, and is characterized in that,

the stator comprises three sections which are coaxial and axially distributed, each section comprises a stator core (1) and stator windings (2), an even number of stator grooves are formed in the stator cores (1), 2 wire rods are arranged in each stator groove, two wire rods in one stator groove are respectively connected with one wire rod in two adjacent grooves in series to respectively form two branches, all the branches are uniformly distributed along the circumferential direction of the stator cores (1), one ends of all the branches are mutually connected in parallel to form one phase of the three-phase windings, and the other ends of all the branches are mutually connected in parallel to serve as midpoints of the three-phase windings.

2. The limit environment natural magnetic suspension switch reluctance energy storage flywheel motor according to claim 1, further comprising a housing (5), wherein the housing (5) is of a vacuum cavity structure, and the rotating shaft, the stator and the rotor (3) are all located in a vacuum cavity (6) of the housing (5).

3. The extreme environment natural magnetic suspension switch reluctance energy storage flywheel motor as claimed in claim 2, wherein two ends of the rotating shaft are respectively connected with the shell (5) through bearings (4).

4. A limit environment natural magnetic suspension switch reluctance energy storage flywheel motor according to claim 3, characterized in that the bearing clearance of the bearing (4) is 0.1 mm-0.5 mm.

5. A limit environment natural magnetic levitation switched reluctance energy storage flywheel motor as claimed in claim 3 or 4 characterized in that a washer (7) is arranged between the bearing (4) and the housing (5).

6. A limit environment natural magnetic levitation switched reluctance energy storage flywheel motor as claimed in claim 2, characterized in that the housing (5) is provided with an electrical interface (8).

7. The limit environment natural magnetic suspension switch reluctance energy storage flywheel motor according to claim 1, wherein the stator is coaxially sleeved outside the rotor (3).

8. The limit environment natural magnetic suspension switch reluctance energy storage flywheel motor according to claim 1, wherein the rotor (3) is coaxially sleeved outside the stator.