A few poles built-in rotor axial flux permanent magnet motor

Abstract

The application relates to a few-pole built-in rotor axial flux permanent magnet motor, which comprises a rotor, a stator and a rotating shaft, the rotor is fixed on the rotating shaft, the stator comprises a first stator and a second stator, the first stator and the second stator are symmetrically arranged on the two sides of the rotor, and the rotor and the rotating shaft rotate relative to the stator; the rotor is composed of a rotor frame, permanent magnets, pole shoes and pressing blocks, a pair of pole shoes cover a plurality of permanent magnets, the pole shoes are symmetrically arranged on the two sides of the permanent magnets, the pressing blocks are pressed on the two adjacent pole shoes, and the pole shoes and the rotor frame of the rotor are connected through a mortise and tenon structure. The application solves the problems of the insufficient strength and reliability of the existing high-speed few-pole double-stator inner rotor axial flux permanent magnet motor, the large eddy current loss of the permanent magnet and the small weak magnetic speed regulation range of the motor.

Description

Technical Field

[0001] This invention belongs to the field of axial flux permanent magnet motor technology, and particularly relates to a dual-stator axial flux permanent magnet motor with a small number of poles. Background Technology

[0002] Surface-mounted dual-stator internal rotor axial flux permanent magnet motors have high power density and compact structure. Their rotors typically adopt a surface-mounted permanent magnet structure, which has some problems: 1) The rotor permanent magnets of high-speed, low-pole, large-diameter motors are large and bear large centrifugal forces and electromagnetic attraction forces from the stator, making the permanent magnets easy to break; 2) The relatively complex permanent magnet structure results in high processing costs and serious waste of permanent magnet materials; 3) The eddy current loss on the surface of the rotor permanent magnets is relatively large; 4) The motor has a small field weakening speed regulation range.

[0003] To improve the rotor structural strength and reduce rotor eddy current losses in axial flux permanent magnet motors with surface-mounted permanent magnet structures, patents (application numbers CN 202010338325.6 and CN201911286316.0) both propose a structure where pole shoes are integrated into a grooved rotor core, with each pole shoe covered by a permanent magnet. This structure is suitable for motors with a large number of poles or a small diameter (i.e., motors with small permanent magnet sizes). Therefore, how to improve the rotor structural strength, reduce rotor eddy current losses, and lower the manufacturing cost of axial flux permanent magnet motors with few poles and large diameters has become a pressing technical and engineering problem that needs to be solved for high-performance dual-stator internal rotor axial flux permanent magnet motors. Summary of the Invention

[0004] Purpose of the invention: This invention provides a structure for a low-pole internal rotor axial flux permanent magnet motor, which aims to solve the problems of insufficient rotor strength and reliability, large eddy current losses of permanent magnets, and small motor field weakening speed regulation range in existing high-speed low-pole double stator internal rotor axial flux permanent magnet motors.

[0005] This invention is achieved through the following technical solution:

[0006] A low-pole built-in rotor axial flux permanent magnet motor includes a rotor, a stator, and a shaft. The rotor is fixed on the shaft. The stator includes a first stator and a second stator, which are mirror-symmetrically arranged on both sides of the rotor. The rotor and the shaft rotate relative to the stator. The rotor consists of a rotor frame, permanent magnets, pole shoes, and pressure blocks. A pair of pole shoes covers multiple permanent magnets and are mirror-symmetrically arranged on both sides of the permanent magnets. The pressure blocks press on two adjacent pole shoes. The pole shoes and the rotor frame of the rotor are connected to each other by a tenon and mortise structure.

[0007] Furthermore, a pair of pole shoes facing each other in the axial direction of the rotating shaft and the one or more permanent magnets they cover together constitute a magnetic pole of the motor.

[0008] Furthermore, multiple permanent magnets covered by the same pole piece are magnetized along the axis of rotation in the same direction, while the permanent magnets covered by adjacent pole pieces along the circumference of the axis of rotation are magnetized in opposite directions.

[0009] Furthermore, the rotor frame includes a frame body, main support ribs, auxiliary support ribs, and permanent magnet slots. Multiple main support ribs are arranged in an array along the circumference of the frame body. Each main support rib has at least two locking holes. A slot shoulder is provided on one side of the main support rib. At least one auxiliary support rib is provided between two adjacent main support ribs. The gap between adjacent main support ribs and auxiliary support ribs or between adjacent auxiliary support ribs is a permanent magnet slot. The rotor frame is made of non-magnetic material.

[0010] Furthermore, among the multiple auxiliary support ribs between two adjacent main support ribs, only one of the auxiliary support ribs has a protruding connecting tenon on each side of the axial direction. The number of main support ribs is equal to the number of magnetic poles of the motor, and the number of auxiliary support ribs is an odd multiple of the number of main support ribs.

[0011] Furthermore, the structure of the extreme boot consists of a boot body, a connecting mortise, and boot shoulders. The boot body is made of silicon steel sheets stacked radially, with a connecting mortise in the middle of the boot body and boot shoulders on the bottom of both sides of the boot body.

[0012] Furthermore, the pressure block is a flat cuboid structure with through holes on it. The number of through holes is equal to the number of locking holes on the main support rib. The pressure block is made of non-magnetic material.

[0013] Furthermore, the stator includes a stator core and m (m≥2) phase stator windings. The stator core includes stator teeth and stator slots, which are distributed alternately along the circumference. The stator windings are embedded in the stator slots.

[0014] The specific advantages of this invention are as follows:

[0015] 1) The motor rotor structure with pole shoes of the present invention not only increases the strength of the rotor and improves the reliability of the motor, but also simplifies the shape of the permanent magnet and reduces the processing cost of the permanent magnet and the manufacturing cost of the motor.

[0016] 2) The motor rotor structure with pole shoes of the present invention increases the difference between the quadrature and direct axis inductances, thus widening the speed regulation range of the motor.

[0017] 3) The motor rotor structure with pole shoes of the present invention reduces the influence of armature harmonic magnetic field on rotor permanent magnet, thereby reducing permanent magnet eddy current loss. Attached Figure Description

[0018] Figure 1 This is a three-dimensional diagram of the low-pole built-in rotor axial flux permanent magnet motor of the present invention;

[0019] Figure 2 This is a diagram of the rotor assembly of the present invention;

[0020] Figure 3 This is an exploded view of the rotor assembly of the present invention;

[0021] Figure 4 This is the motor magnetic pole diagram of the present invention;

[0022] Figure 5 This is a diagram of the rotor frame of the present invention;

[0023] Figure 6 This is a diagram of the pole shoe of the present invention;

[0024] Figure 7 This is the stator diagram of the present invention;

[0025] Figure 8 This is an exploded view of the rotor assembly in Embodiment 2 of the present invention;

[0026] Figure 9 The rotor permanent magnet eddy current loss of traditional surface-mount motors and the motor of this invention;

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. Rotor, 101. Rotor frame, 1011. Frame body, 1012. Main support rib, 1013. Auxiliary support rib, 1014. Permanent magnet slot, 1015. Locking hole, 1016. Connecting tenon, 1017. Slot shoulder, 102. Permanent magnet, 103. Pole shoe, 1031. Shoe body, 1032. Connecting mortise, 1033. Shoe shoulder, 104. Pressure block, 105. Fixing component, 2. Stator, 201. Stator core, 202. Stator winding, 201. Stator core, 2011. Stator tooth, 2012. Stator slot, 3. Shaft. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] Example 1

[0031] like Figure 1 As shown, a low-pole built-in rotor axial flux permanent magnet motor includes a rotor 1, a stator 2 and a rotating shaft 3. The rotor 1 is fixed on the rotating shaft 3. The stator 2 includes a first stator 2A and a second stator 2B. The first stator 2A and the second stator 2B are mirror-symmetrically arranged on both sides of the rotor 1. The rotor 1 and the rotating shaft 3 rotate relative to the stator 2.

[0032] like Figure 2 and Figure 3As shown, the rotor 1 consists of a rotor frame 101, permanent magnets 102, pole shoes 103, pressure blocks 104, and fixing components 105. One pole shoe 103 covers two permanent magnets 102. The pole shoes 103 are placed symmetrically on both sides of the permanent magnets 102. The pressure blocks 104 press on the two adjacent pole shoes 103. The pole shoes 103 and the rotor frame 101 are connected to each other by a tenon and mortise structure.

[0033] like Figure 4 As shown, the two axially aligned pole shoes 103 and the two permanent magnets 102 they cover together constitute one magnetic pole of the motor; in different embodiments, each permanent magnet 102 can be a trapezoidal or sector-shaped structure, correspondingly, Figure 5 The permanent magnet slots 1014 on the rotor frame 101 are also designed as corresponding trapezoidal slots or sector slots; the permanent magnet 102 has a simple structure, unlike the irregular structure of the permanent magnet with bosses in the traditional axial flux motor (which is for fixing the permanent magnet). The structure of the present invention reduces the processing and manufacturing cost of the permanent magnet and saves permanent magnet materials.

[0034] Taking an 8-pole motor as an example, Figure 3 and Figure 4 The invention features a pole shoe 103 covering two permanent magnets 102. In traditional permanent magnet motors, one pole consists of a single permanent magnet. This structure results in a semi-circular permanent magnet in a two-pole motor, making the permanent magnet highly susceptible to breakage. Therefore, this invention divides a single permanent magnet into two or more permanent magnets, which together form a single pole. This structure solves the problem of large permanent magnets being easily broken. The pole shoe 103 covering multiple permanent magnets 102 not only simplifies the fixing method of permanent magnet poles in traditional motors, but also weakens the eddy current losses generated by the harmonic magnetic field of armature reaction on the permanent magnets 102. Furthermore, the presence of the pole shoe 103 changes the magnetic permeability of the quadrature and direct-axis magnetic circuits of the motor, thereby changing the difference in inductance between the quadrature and direct axes and improving the motor's field weakening speed regulation capability.

[0035] Furthermore, multiple permanent magnets 102 covered by the same pole piece 103 are magnetized along the axial direction (AX) with the same magnetization direction, while the permanent magnets 102 under adjacent pole pieces 103 in the circumferential direction (CI) are magnetized in opposite directions. Figure 3 An example is given of a magnetic pole consisting of two permanent magnets, which together form either a magnetic pole (N) or a magnetic pole (S).

[0036] like Figure 5 As shown, the rotor frame 101 includes a frame body 1011, main support ribs 1012, auxiliary support ribs 1013, and permanent magnet slots 1014. Each main support rib 1012 has at least two locking holes 1015. A slot shoulder 1017 is provided on one side of the main support rib 1012. At least one auxiliary support rib 1013 is provided between two adjacent main support ribs 1012. The rotor frame 101 is made of non-magnetic material.

[0037] like Figure 5 An example is given where there is only one auxiliary support rib 1013 between two adjacent main support ribs 1012. Each of the auxiliary support ribs 1013 has a protruding connecting tenon 1016 on both sides of the axial direction. The number of main support ribs 1012 is equal to the number of magnetic poles of the motor, and the number of auxiliary support ribs 1013 is equal to the number of main support ribs 1012.

[0038] like Figure 6 As shown, the extreme boot 103 is composed of boot body 1031, connecting mortise 1032, and boot shoulder 1033. The boot body 1031 is made of silicon steel sheets stacked radially. The connecting mortise 1032 is provided in the middle of the boot body 1031, and the boot shoulder 1033 is provided at the bottom of both sides of the boot body 1031.

[0039] like Figure 3 As shown, the pressure block 104 is a flat cuboid with through holes on it. The number of through holes is equal to the number of locking holes 1015 opened on the main support rib 1012. The pressure block 104 is made of non-magnetic material.

[0040] like Figure 2-4 As shown, the permanent magnet 102 is placed in the permanent magnet slot 1014 on the rotor frame 101. The connecting tenon 1032 on the pole shoe 103 and the connecting tenon 1016 on the auxiliary support rib 1013 engage with each other. In the axial direction (AX), the shoulder 1033 on one side engages with the slot shoulder 1017 of the rotor frame 101, and the shoulder 1033 on the other side presses against the pressure block 104. The fixing member 105 passes through the through hole on the pressure block 104 and the locking hole 1015 on the main support rib 1012 to lock the two pole shoes 103 facing each other in the axial direction and the multiple permanent magnets 102 built in them to the rotor frame 101.

[0041] like Figure 7 As shown, stator 2 includes stator core 201 and m (m≥2) phase stator windings 202. Stator core 201 includes stator teeth 2011 and stator slots 2012, which are distributed alternately along the circumference. The stator windings 202, according to motor winding theory, place coils of a specified number of turns into the corresponding stator slots 2012.

[0042] Example 2

[0043] In addition to the embodiments described above, the present invention can also be implemented as follows: Figure 8 As shown, Figure 8One pole piece 103 covers four permanent magnets 102. One magnetic pole contains four permanent magnets. These four permanent magnets together form a magnetic pole (N) or a magnetic pole (S). Three auxiliary support ribs 1013 are set between two adjacent main support ribs 1012. Each of the middle auxiliary support ribs 1013 has a protruding connecting tenon 1016 on both sides of the axial direction. The number of main support ribs 1012 is equal to the number of magnetic poles of the motor. The number of auxiliary support ribs 1013 is three times that of the main support ribs 1012.

[0044] The high-speed, low-pole dual-stator internal rotor axial flux permanent magnet motor of the present invention has high rotor strength, low permanent magnet eddy current loss, and a wide motor field weakening speed regulation range. Furthermore, it simplifies the permanent magnet shape and reduces the motor's manufacturing cost. Figure 9 The figure shows that the rotor permanent magnet eddy current loss of the motor of the present invention is greatly reduced compared to that of the traditional surface-mount motor.

Claims

1. A few-pole built-in rotor axial flux permanent magnet motor, comprising a rotor (1), a stator (2) and a rotating shaft (3), the rotor (1) is fixed on the rotating shaft (3), the stator (2) comprises a first stator (2A) and a second stator (2B), the first stator (2A) and the second stator (2B) are symmetrically arranged on both sides of the rotor (1), and the rotor (1) and the rotating shaft (3) rotate relative to the stator (2) ; characterized in that: the rotor (1) is composed of a rotor frame (101), permanent magnets (102), pole shoes (103) and pressing blocks (104), a pair of pole shoes (103) cover a plurality of permanent magnets (102), the pole shoes (103) are symmetrically arranged on both sides of the permanent magnets (102), and the pressing blocks (104) are pressed on the adjacent two pole shoes (103), the pole shoes (103) and the rotor frame (101) of the rotor (1) are connected by a mortise and tenon structure; a pair of pole shoes (103) and the plurality of permanent magnets (102) covered thereby in the axial direction of the rotating shaft (3) together constitute a magnetic pole of the motor; the plurality of permanent magnets (102) under the same pole shoe (103) are magnetized along the axial direction of the rotating shaft (3), and the magnetization directions are the same, and the permanent magnets (102) under the adjacent two pole shoes (103) along the circumferential direction of the rotating shaft (3) are magnetized in opposite directions; the rotor frame (101) comprises a frame body (1011), main support ribs (1012), auxiliary support ribs (1013) and permanent magnet grooves (1014), a plurality of main support ribs (1012) are arranged in the circumferential direction of the frame body (1011), at least two locking holes (1015) are formed in each main support rib (1012), a groove shoulder (1017) is arranged on one side of the main support rib (1012), not less than one auxiliary support rib (1013) is arranged between the adjacent two main support ribs (1012), and the space between the adjacent main support ribs (1012) and auxiliary support ribs (1013) or the adjacent auxiliary support ribs (1013) is the permanent magnet groove (1014), and the rotor frame (101) is a non-magnetic material; wherein a through hole is formed in the pressing block (104), the rotor (1) further comprises a fixing member (105), the pole shoe (103) is provided with a connecting mortise (1032) and a shoe shoulder (1033), and at least one auxiliary support rib (1013) is provided with a connecting tenon (1016) ; the mortise and tenon structure comprises the engagement connection between the connecting mortise (1032) and the connecting tenon (1016) ; in the axial direction of the rotating shaft (3), the shoe shoulder (1033) on one side of the pole shoe (103) engages with the groove shoulder (1017) on one side of the main support rib (1012), the shoe shoulder (1033) on the other side is in pressure connection with the pressing block (104), the fixing member (105) passes through the through hole in the pressing block (104) and the locking hole (1015) in the main support rib (1012), and the two pole shoes (103) and the plurality of permanent magnets (102) covered thereby in the axial direction of the rotating shaft (3) are locked to the rotor frame (101).

2. The axial flux PM motor with few poles built-in rotor according to claim 1, characterized in that The plurality of auxiliary support bars (1013) between the two adjacent main support bars (1012) have only one protruding connecting tenon (1016) on each axial side of one of the auxiliary support bars (1013), the number of the main support bars (1012) is equal to the number of magnetic poles of the motor, and the number of the auxiliary support bars (1013) is an odd multiple of the number of the main support bars (1012).

3. The axial flux PM motor with few poles built-in rotor of claim 1, characterized in that The structure of the pole shoe (103) is composed of a shoe body (1031), a connecting dowel (1032) and a shoe shoulder (1033), the shoe body (1031) is composed of silicon steel sheets stacked in the radial direction, the middle of the shoe body (1031) is provided with the connecting dowel (1032), and the bottom of the two sides of the shoe body (1031) is provided with the shoe shoulder (1033).

4. The axial flux PM motor with few poles built-in rotor of claim 1, characterized in that The pressing block (104) is a flat rectangular parallelepiped structure, a through hole is formed on the upper surface of the pressing block (104), the number of the through hole is equal to the number of the locking holes (1015) formed on the main support bars (1012), and the pressing block (104) is a non-magnetic material.

5. The axial flux PM motor with few poles built-in rotor of claim 1, characterized in that The stator (2) comprises a stator core (201) and m-phase stator windings (202), the stator core (201) comprises stator teeth (2011) and stator slots (2012), the stator teeth (2011) and the stator slots (2012) are distributed alternately along the circumference, and the stator windings (202) are embedded in the stator slots (2012), wherein m≥2.

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