WO2023242882A2

WO2023242882A2 - Surface-mounted permanent magnet synchronous motor with high fixation and improved magnet performance on the surface

Info

Publication number: WO2023242882A2
Application number: PCT/IR2022/050022
Authority: WO
Inventors: Mehdi ABDOLMALEKI
Original assignee: Abdolmaleki Mehdi
Priority date: 2022-06-13
Filing date: 2022-06-13
Publication date: 2023-12-21
Also published as: WO2023242882A3

Abstract

In this description of invention the structure of a surface-mounted permanent magnet synchronous motor with high fixation and improved magnet performance on the rotor surface is proposed. The technical field of this invention is related to the string of power electrical engineering, design and construction of electric machines, including permanent magnet synchronous machines, especially related to the optimal structure of the rotor in order to high fixation the permanent magnet on the rotor surface and Prevention of centrifugal force and the magnets separate in Surface-mounted permanent magnet synchronous motors. Which is a prevalent and widely used motor. In this type of motor, a magnet is mounted on the rotor surface. The problem with this type of motor is that at high speeds or in when starting and accelerating, involved the magnets slip and centrifugal force and may moveing out of place and cause problems in motor performance. Because, the magnet is an important part of the excitation of the surface permanent magnet synchronous motor. Therefore, it will be very desirable to control and reduce this problem. Therefore, for the purpose of technical problem, to proposed a solution using T-shaped permanent magnets in the direction of the axis whose surface is on the surface of the rotor and the base of T-shaped permanent magnets are buried inside the rotor so that the centrifugal force and its slip is neutralized during acceleration and starting, and higher mechanical endurance can be achieved at high speeds. Other advantages that can be achieved with this invention are a significant reduction in the volume of the permanent magnet consumed, weight reduction and cost. The results have been study and analyzed by FEM 2D and Maxwell software. The results of the proposed new structure show the accuracy of better and more optimal performance and the achievement of the mentioned purposes.

Description

Title of Invention: {Surface-mounted permanent magnet synchronous motor with high fixation and improved magnet performance on the surface

{Technical Field

[0001] The technical field of this invention is related to the string of power electrical engineering, design and construction of electric machines, including permanent magnet synchronous machines, especially related to the optimal structure of the rotor in order to high stabilize the magnet on the rotor surface and Prevention of centrifugal force and the magnets separate in Surface-mounted permanent magnet synchronous motors.

Technical problem and expression of invention purposes

[0002] Permanent magnet synchronous motors are in truth a normal synchronous motor that uses a permanent magnet instead of excitation of the rotor winding, brushes and slip rings and because of their advantages such as having high power density, high efficiency, good power factor and lower sensitivity to voltage and frequency change of power supply for industrial applications such as fans driver, pumps and compressors are very desirable and are preferred over DC and induction motors in many applications with better behavior. In permanent magnet synchronous motors with surface magnets by placing the magnet on the rotor surface in high speed applications due to the possibility of separate and centrifugal of magnets will not be desirable and are not used much because they need ongoing monitoring and check because the magnet is an important part of the permanent magnet synchronous motor and creating a problem in it causes creating a problem in the performance of the motor and this subject will not be desirable in terms of performance. It will also be very desirable to reduce the consumable volume of the magnet without reducing the performance of the motor, which also leads to a reduction in weight and cost. Therefore the purpose of this invention is to proposed a solution to solve this problem, improve the performance and further hold the magnet in place and in addition reduce the consumable volume of the permanent magnet without reducing the performance in surface permanent magnet synchronous motors.

Background Art

[0003] In recent years, with the advent of magnetic materials to excite electric machines, there has been a rapid and considerable growth in the technology of making electric machines based on a permanent magnet excitation system, and there are many researchers in order to optimize the structure of this type of machine and increase their performance. Permanent magnet synchronous machines (motors and generators) are used in two types of surface magnets and internal magnets. In the type of interior magnet due to the placement of the magnet inner the rotor cause increases the mechanical endurance of the magnet and is mostly used in high-speed applications. In the surface magnet type the magnet is placed on the rotor surface with special adhesives in the form of cylindrical or salient pole. In this type of structure the magnet in highspeed applications may be separate from the rotor surface by centrifugal force and or cause slip of place during starting and acceleration and it is a technical problem in this type of structure because the magnet is an important part of the permanent magnet synchronous motor. Therefore, solving or reducing the occurrence of this problem in this type of machine structure, stabilizing and fixing more magnets, as well as achieving a reduction in magnet consumption Volume without reducing motor performance, which leads to weight and cost reduction will be very desirable. In order to solve this problem, various structures have been developed by researchers, which are briefly discussed:

[0004] In patent document with publication number No. 1020170062889 issued in 2017 by the Republic of Korea discloses a method for fixation a magnet on the rotor surface in permanent surface magnet synchronous motors. This is done by placing a non-magnetic cap-like or belt member on both side of the rotor that is attached separately to the rotor core which surrounds the magnets and holds them in place. In patent document with publication number No. 107332378 issued in 2017 by China, it disclosed a rotor structure of a surface-mounted permanent magnet synchronous servo motor to fixing permanent magnets on the rotor surface. This is done by the rotor punching sheet (fist shape) and plurality of magnetic isolation bridge structures arranged on the periphery of the punching sheet body; which is a member of the rotor core and is between spaced adjacent permanent magnet that permanent magnets correspond to the shape of the rotor punching sheet holding piece and are placed between them, and the magnets are mounted on the rotor surface, keeping the magnets fixed on the rotor surface. In patent document with publication number No. 209948817 issued by China in 2020, it discloses an improved design of the rotor structure for a permanently mounted magnetic synchronous motor that can fixing permanent magnets in place. This is done by designing the rotor structure with protrusions from the rotor surface that is a member of the rotor core and in the form of a punch the magnets are thinned from the middle to the edges, and the rotor punches, which are member of the rotor core, surround the edges of the magnets and holds permanent magnets fixed. In patent document with publication number No. 210669664 issued in 2020, China disclosed a model of a permanent magnet synchronous motor rotor structure for fixation a permanent magnet to the rotor surface, which is characterized in that a plurality of magnetic isolation buckle pairs are arranged on the circumference of a rotor substrate, each magnetic isolation buckle pair comprises a left buckle and a right buckle, each buckle comprises a radial elastic body, the magnetic steel is clamped between the left buckle and the right buckle of the corresponding magnetic isolation buckle pair through the clamping of the bayonet and the clamping head; gaps capable of being filled with binders are reserved between the lower arc parts of the magnetic steels and the rotor substrate and between the left and right side parts of the magnetic steels below the left and right bayonets and the left and right elastomers, and gaps for assembling tooling operation are reserved between the left and right side parts of the magnetic steels above the left and right bayonets and the upper parts of the left and right elastomers and according to the utility model, reliable fixation of the magnetic steel is realized, vibration and noise are effectively reduced. In patent document with publication number No. 110829649 issued in 2020 by China, it discloses a rotor structure for a surface-mounted permanent magnet synchronous servo motor that helps fix permanent magnets on the rotor surface. The permanent magnet synchronous servo motor rotor comprises permanent magnets and a rotor iron core, the permanent magnets adopt a partitioning strategy, the number of partitioned magnets is larger than or equal to 3, and the lengths of the partitioned magnets along the circumference are equal. The rotor core is provided with wedge-shaped buckles by utilizing a gap between the magnetic poles after the magnets are partitioned, and the buckles are used for fixing the permanent magnet on the rotor. In patent document with publication number No. 109546777 issued in 2019 by China, it disclosed a rotor structure to improve the performance of a permanently mounted surface-mounted magnetic synchronous motor, rotor punching sheet, T-shaped wedges, axial direction trapezoid ventilation holes, permanent magnets, and grooves disposed at the periphery of the permanent magnets. In patent document with publication number No. 109546777 issued in 2019 by China, it disclosed a rotor structure to improve the performance of a permanently mounted surface-mounted magnetic synchronous motor, rotor punching sheet, T-shaped wedges which member of rotor core, axial direction trapezoid ventilation holes, permanent magnets, and grooves disposed at the periphery of the permanent magnets. The rotor structure is characterized in that: the T-shaped wedges which member of rotor core on the periphery of the rotor punching sheet is used for fixing the permanent magnets; the trapezoid ventilation holes are equidistantly distributed along the circumferential direction of a rotor; two curved grooves are formed on the periphery of each of the permanent magnets to improve the unevenness of an air gap. And the shape of the magnet poles that correspond to the T-shaped wedges is placed on it so that the T-shaped wedges which member of rotor core are placed inside the magnet and cause them to be fixed on the rotor surface. Some of the proposed structures use permanent surface buried magnets. Because the magnet is of great importance in surface-mounted permanent magnet synchronous machines, it can cause problems such as slipping and separating from the magnet, or causing the motor to malfunction. Therefore, as stated, the purpose of this invention is to provide a method for further stabilization and fixing of the magnet on the rotor surface in Surface-mounted permanent magnet synchronous motor and also in addition to achieve a reduction in magnet consumption volume without reducing performance that reduces weight and cost.

Solution to Problem and Description of Embodiments

[0005] In this section, proposed solutions to achieve the above are described in detail. The embodiment of the existing technical disclosure solution of the present invention is shown in Fig.1 As can be seen the structure of the motor includes: The stator core 11 has a number of slots 12 in which the three-phase windings are placed and the rotor core 13 which is located inside the stator core 11 has 4 poles with T-shaped permanent magnets 14 whose surface is on the surface of the rotor 13 and the base of the T-shaped permanent magnets 15 is located inside the rotor core 13 and are installed at regular spacing and in the axial direction on the surface of the rotor 13 as a smooth pole and it has magnet flux barriers 16, circular ventilation holes 17 around the flux barriers 16 and also the rotor shaft 18. With this proposed structure, compared to the conventional structure with surface permanent magnet, higher mechanical strength can be achieved at high speeds because the base of the T-shaped permanent magnets 15 is harnessed inside the rotor 13, and its centrifugal force and slip when starting and acceleration are neutralized. Also by placing a part of the magnet inside the rotor more difference can be achieved between the inductances of the d and q axes, which cause create reluctance torque and significantly reduce the consumption volume permanent magnet, weight, cost and to be economical, and as well as improve motor performance. The effect of the present invention is not limited to a 4-pole motor and this type of magnet and can be applied to a number of other poles and magnet types. The base size of a T-shaped permanent magnets 15 is obtained using the relation C = which is shown in Fig. 2. In this relation, C is the base size of the T-shaped

permanent magnets 15, A is the outer radius of the rotor, B is the height of the magnet, 2.4 is a fixed number to achieve the desirable value and result. The size of the base of T-shaped permanent magnet 15 can not be less than this, Because the result will not be desirable and can even more if necessary. The thickness of the base of a permanent T-shaped magnet 15 is the same as the thickness of a surface magnet 14 and can also be varied if necessary. The specifications and features of the mentioned motor structure are given in Table 1. The performance of the mentioned motor in starting and loading cases is shown by FEM 2D simulation based on Ansys Maxwell in Figs. 3a-d. The motor optimization is done by changing the parameters in the Ansys Maxwell environment. Starting the motor is simulated in no-load conditions for time 0 < t< 0.4s. Load changing is also investigated by applying one constant load equivalent to TL = 30 Nm at time T = 0.4s. The output torque is shown in Fig. 3a. As can be seen the average output torque is equal to the torque of the load. It is also intended to reduce the simulation time of the motor at the rated speed of 1500 RPM and the stable state, shown in Fig. 3b and Stator currents and copper losses are also shown in Figs. 3c and d. In Figs. 4a and b, respectively; the density distributions of the magnetic flux as well as the flux lines are shown in the rated load. As can be seen, the maximum magnetic flux density is at different parts of the stator and rotor 1.24 T, which is not saturated and the motor does not go saturated. To validate the accuracy of the reduced permanent magnet consumable volume under the proposed structure of a typical Surface-mounted permanent magnet synchronous motor to achieve the same performance and torque has been performed which is shown in Fig. 5a. The mentioned motor characteristics are the same as the structure of the disclosed invention, except that it is used to achieve the same performance using conventional structure, which Includes: Stator core 51 stator slots 52 that the three-phase coils are in placed, permanent magnets 53 on the surface of the rotor 54 that is placed as a smooth pole and the rotor shaft 55. Whit the study of done the reduction in the consumable volume of permanent magnet 56 under the proposed structure of the present invention compared to the consumed volume permanent magnet in a pole of typical structure 53 show in Fig. 5. As can be seen, the proposed structure has a considerable reduction in the volume of the consumed permanent magnet without reducing the performance, which reduces the weight and cost at each pole of the magnet, which will be much more desirable and cost-effective and it also cause stability and high Mechanical endurance the magnet at high speeds and improving the performance of the magnet on the rotor surface. The results of the conventional structure are performed by FEM 2D simulations based on the Maxwell Ansys which is shown in Figs. 6a-d. The starting and loading conditions of the motor are the same as the conditions of the previously proposed structure, so its explanation has been removed. Fig. 6a shows the output torque. As can be seen, the average output torque is equal to the load torque and has the same function. Then the motor speed and stator currents are shown in Figs. 6b-d. As can be seen, it has the same function and the stator current in the no loaded case is 1 A more than the proposed structure and the proposed structure has a better performance, which this reduction in current also reduces copper losses. Therefore, the proposed structure of the present invention, in addition to neutralizing the centrifugal force and sliding of the magnet, also provides a significant reduction in the consumption volume of the permanent magnet without reducing motor performance, which leads to weight and cost reduction. Therefore, with the proposed structure can be achieved result and the performance a more desirable of the magnet on the rotor surface, usual people who are skilled in the technique will understand that the proposed structure is different from the other structures presented, new and better than the conventional structure. Therefore, with the proposed disclosed invention, in applications where the surface-mounted permanent magnet synchronous motor is used, especially at high speeds, and due to the mentioned problem, needed it improves the performance of the magnet, more optimal performance, lower weight and cost-effectiveness, proposed motor structure is very advantageous.

Brief Description of Drawings

Fig.1

[0006] [fig.1 ] The total two-dimensional structure of the motor is by embodiment the existing disclosure technical solution of the present invention.

Fig.2

[0007] [fig.2] View of the motor and placement of T-shaped permanent magnet.

Fig.3 [0008] [fig.3] 2D FEM simulation results in starting and loading cases under the embodiment of the present invention.

Fig.4

[0009] [fig.4] Distribution of magnetic flux density and flux lines under the embodiment of the present invention.

Fig.5-a

[0010] [fig.5-a] typical structure of Surface-mounted permanent magnet synchronous motor.

Fig.5-b

[0011] [f ig .5-b] Comparison of the reduction in the volume of permanent magnet consumption of the proposed structure with the typical structure.

Table.1

[0012] [table.1] Dimensions and structural Characteristic of surface permanent magnetic synchronous motor.

Advantageous Effects of Invention

[0013] Given the above, the advantages of the proposed invention structure are:

1 . With this motor structure, high stability and fixation and improvement of magnet performance on the rotor surface can be achieved;

2. With this motor structure, higher mechanical endurance can be achieved at high speeds;

3. Has a significant reduction in the consumption volume of permanent magnets;

4. Less weight and cost;

5. It is safe to say that the proposed structure can be a suitable and desirable alternative to the previous and typical structure;

Description at least one executive method for applying the invention

[0014] In recent years, the use of permanent magnet synchronous motors, especially PMSMs, due to their advantages and good efficiency, for use in the military industry, hybrid or electric vehicles, centrifuges and many other applications taken. And investigations show that in the type of surface magnet with smooth pole of the permanent magnet synchronous motor, due to more use and the problem expressed in this type of motor, it is to provide a design and structure of a Surfacemounted permanent magnet synchronous motor with high stability and to improve the performance of the magnet on the rotor surface propose.

Industrial Applicability of the invention

[0015] The proposed motor can be used in military industries, hybrid or electric vehicles, centrifuges and other applications that needed a Surface-mounted permanent magnet synchronous motor installed at high speeds with high reliability

Summary of the Invention

[0016] In this description of invention the structure of a surface-mounted permanent magnet synchronous motor with high fixation and improved magnet performance on the rotor surface is proposed. The technical field of this invention is related to the string of power electrical engineering, design and construction of electric machines, including permanent magnet synchronous machines, especially related to the optimal structure of the rotor in order to high fixation the permanent magnet on the rotor surface and Prevention of centrifugal force and the magnets separate in Surface-mounted permanent magnet synchronous motors. Which is a prevalent and widely used motor. In this type of motor, a magnet is mounted on the rotor surface. The problem with this type of motor is that at high speeds or in when starting and accelerating, involved the magnets slip and centrifugal force and may moveing out of place and cause problems in motor performance. Because, the magnet is an important part of the excitation of the surface permanent magnet synchronous motor. Therefore, it will be very desirable to control and reduce this problem. Therefore, for the purpose of technical problem, to proposed a solution using T-shaped permanent magnets in the direction of the axis whose surface is on the surface of the rotor and the base of T-shaped permanent magnets are buried inside the rotor so that the centrifugal force and its slip is neutralized during acceleration and starting, and higher mechanical endurance can be achieved at high speeds. Other advantages that can be achieved with this invention are a significant reduction in the volume of the permanent magnet consumed, weight reduction and cost. The results have been study and analyzed by FEM 2D and Maxwell software. The results of the proposed new structure show the accuracy of better and more optimal performance and the achievement of the mentioned purposes, i

Claims

[Claim 1] i What is claimed to be a permanent magnet synchronous motor comprising of a stator core which is the static part of the motor body and a rotor core which is the moving part of the motor and is placed inside the stator core and instead of excitation of the rotor winding of the T-shaped permanent magnets with regular intervals and in the axial direction have been used which provides high fixation and improved magnet performance on the rotor surface. This motor comprising of the following components:

- Stator core;

- Stator slots in which three-phase windings are placed;

- Rotor core;

- T-shaped Permanent magnets;

- The base of T-shaped Permanent magnets;

- Magnet flux barriers;

- Circular ventilation holes;

- Rotor shaft;