Sectional modular stator motor and motor rotor

Abstract

The utility model provides a sectional type modularized stator motor and a motor rotor. The rotor is equally divided into at least two axial rotor sections along the axial direction, the adjacent axial rotor sections are mutually deflected by a deflection angle along the circumferential direction, the deflection angle is set according to the following formula, the deflection angle is equal to k * 360 / Max (slot number and pole number) / n, k is equal to 0.75-0.85, Max (slot number and pole number) is the larger one of the slot number and the pole number of the motor, and n is the number of the axial rotor sections. The motor comprises the rotor. The motor and the rotor provided by the utility model can reduce higher low-order (for example, 10-order) cogging torque harmonic waves and (for example, 12-order) torque pulsation.

Description

Technical Field

[0001] The utility model relates to the field of electric motors, in particular to permanent magnet electric motors. Specifically, in a first aspect, the utility model relates to a rotor for a segmented modular stator electric motor. In a second aspect, the utility model relates to a segmented modular stator electric motor comprising the rotor. Background Art

[0002] Segmented modular stator motors are widely used as vehicle steering motors and servo motors due to their high winding slot fill rate and power density. The stator is equally divided into several stator segments along the circumferential direction, and the stator segments are configured as stator teeth. In order to arrange the armature winding in the motor, it is necessary to set tooth slots (defined by adjacent stator teeth) in the stator armature core. This will cause the interaction between the rotor permanent magnets and the stator armature core, resulting in a tooth slot torque, which is caused by the tangential component of the interaction force between the rotor permanent magnets and the armature tooth slots. In addition, this construction will also cause the motor to produce torque pulsation.

[0003] In order to weaken the adverse effects of cogging torque and torque pulsation, the means used include stator skew slots or rotor (magnet) skew poles, so that the cogging torque harmonics of the armature winding are in different phases, thereby weakening the cogging torque harmonics of each order by offsetting a part of the cogging torque harmonics, and thus reducing the cogging torque and torque pulsation. Due to the complex process of the stator skew slot method, the rotor skew pole method is usually used. Rotor skew poles can be divided into two types, one is continuous skew poles and the other is segmented skew poles. Continuous skew poles require the manufacture of permanent magnets of special shapes, which is costly and difficult to assemble, so it is difficult to implement. Segmented skew poles divide the rotor into several equal rotor segments along the axial direction, and the adjacent rotor segments are skewed to each other by a certain skew angle (mechanical angle). The process is relatively simple, so in practice, rotor segmented skew poles are usually used to reduce the cogging torque and torque pulsation of the motor.

[0004] Examples of segmented skewed-pole rotors are disclosed in, for example, US2014084744A1, WO2022193175A1, JP2004274826A, JP2009213283A, JP2010051150A, JP2012010425A, JP2012023823A, and US2009224619A1. JP2009213283A, JP2010051150A, and JP2012023823A also disclose segmented modular stators.

[0005] For example, for a 12-slot 10-pole motor, the calculated skew angle is 3 degrees according to the formula: skew angle = 360 / least common multiple (number of slots, number of poles) / n (number of axial rotor segments). This structure can offset 60th-order cogging torque harmonics and 30th-order torque ripples.

[0006] However, due to production and assembly errors, there may be gaps between adjacent stator segments, and each gap is inconsistent. For example, the gap range may be 0-0.15 mm, and the standard deviation may be 0.01-0.05 mm. At the same time, for surface-mounted rotors, that is, the magnets are mounted on the outer circumferential surface of the rotor core, each segment of the magnet mounted on the outer circumferential surface of each segment of the rotor core has contour defects and tangential misalignment errors. This will result in higher additional low-order (order is the number of poles) cogging torque harmonics. In this case, under motor load conditions, the main components are the 10th-order cogging torque harmonics and the 12th-order torque pulsation, which are different from the theoretical 60th-order cogging torque harmonics and the 30th-order torque pulsation, resulting in the above calculated skew angle being invalid. Utility Model Content

[0007] The utility model aims to overcome the defects of the existing method of setting the deflection angle. The utility model aims to improve the method of setting the deflection angle to offset the higher low-order (such as 10th order) cogging torque harmonics and (such as 12th order) torque pulsation.

[0008] According to the first aspect, the utility model proposes a motor rotor, which is equally divided into at least two axial rotor sections along the axial direction, and adjacent axial rotor sections are circumferentially deviated from each other by a deflection angle. According to the utility model, the deflection angle is set according to the following formula: deflection angle = k*360 / Max (number of slots, number of poles) / n, where k = 0.75-0.85, Max (number of slots, number of poles) is the larger of the number of slots and the number of poles, and n is the number of axial rotor sections. For example, for a 12-slot 10-pole motor, when k is selected as 0.8, the mechanical angle = 12 degrees. Since there are 10 poles, the electrical angle is the number of pole pairs * 12, that is, 5*12 = 60 degrees.

[0009] According to an embodiment, the rotor is a two-segment type, that is, it is equally divided into two axial rotor segments in the axial direction. Preferably, the first (axially upper) axial rotor segment is tilted by half a tilt angle in the counterclockwise direction in the circumferential direction relative to the arrangement of the two rotor segments not tilted to each other, and the second (axially lower) axial rotor segment is tilted by half a tilt angle in the clockwise direction in the circumferential direction relative to the arrangement of the two rotor segments not tilted to each other.

[0010] According to a second aspect, the utility model provides a motor, which comprises the above-mentioned rotor.

[0011] According to an embodiment, the electric machine comprises a segmented modular stator which is equally divided into a number of stator segments in a circumferential direction, adjacent stator segments define tooth slots, and the stator windings are arranged in the tooth slots.

[0012] According to an embodiment, two diametrically opposed stator windings constitute one phase.

[0013] According to an embodiment, the stator winding is divided into two three-phase systems, and the stator windings of the same phase system are arranged adjacent to each other in the circumferential direction.

[0014] According to an embodiment, the motor is a 12-slot 10-pole motor. In this example, the stator is provided with 12 stator windings, which form 6 phases.

[0015] According to an embodiment, different phase systems feed current at different flux weakening angles (ie with current waveforms of different phase shifts). With this arrangement, the motor output torque can be maximized compared to feeding current without phase shift.

[0016] Preferably, the field weakening angle of the first phase system is shifted by a certain angle relative to the back-EMF zero position without phase shift, and the field weakening angle of the second phase system is shifted by a certain degree relative to the back-EMF zero position without phase shift.

[0017] To this end, the motor also includes an electronic control unit, which is configured to feed current to the first and second phase systems according to the following formula: for the first phase system, Irms*1.414*sin(2π*f*t+b1), for the second phase system, Irms*1.414*sin(2π*f*t+b2) feed current, where Irms is the effective value of the current, f is the current frequency, t is the time, b1 is the lagging phase shift angle of the first phase system relative to the back electromotive force zero position without phase shift, ranging from -10 to 13 degrees, and b2 is the leading phase shift angle of the second phase system relative to the back electromotive force zero position without phase shift, ranging from 15 to 18 degrees. The above two angles can compensate for the reduction in motor output torque caused by the large deflection angle, and can effectively reduce low-order torque pulsation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The embodiments of the present invention will be explained in more detail in the accompanying drawings, in which:

[0019] Figure 1 It is a structural schematic diagram of the stator of the segmented modular stator motor of the embodiment of the utility model;

[0020] Figure 2 It is a structural schematic diagram of a part of a segmented skewed-pole rotor according to an embodiment of the utility model;

[0021] Figure 3 yes Figure 2 The rotor is mounted on Figure 1 Schematic diagram of the structure in the stator;

[0022] Figure 4A yes Figure 1 An equivalent circuit diagram of a first set of stator windings of a stator in;

[0023] Figure 4B yes Figure 1An equivalent circuit diagram of a second set of stator windings of the stator in;

[0024] Figure 5 yes Figure 4A and Figure 4B Schematic diagram of the phase shift angles of the two sets of stator windings;

[0025] Figure 6 is a schematic diagram of the relationship between the skew angle and the cogging torque, motor output torque and torque pulsation reduction;

[0026] In the drawings, embodiments of the present invention are shown in a simplified manner for the sake of clarity. DETAILED DESCRIPTION

[0027] Figure 1 The stator of a segmented modular stator motor with 12 slots and 10 poles according to an embodiment of the present invention is shown. Figure 2 The rotor of the segmented skewed pole of the embodiment of the utility model is shown. As shown in the figure, the stator is equally divided into 12 stator segments along the circumferential direction, and the rotor is a surface-mounted structure, that is, the magnet is mounted on the outer circumferential surface of the rotor core, and is equally divided into 10 rotor segments along the circumferential direction, and is equally divided into 2 segments along the axial direction (i.e., a 2-segment rotor).

[0028] exist Figure 1 In the example of , the 12 stator teeth are numbered as stator tooth 1 to stator tooth 12. The gap between stator tooth 1 and stator tooth 2 is 0.05 mm, the gap between stator teeth 6-7, stator teeth 7-8, stator teeth 8-9 and stator tooth 12-1 is also 0.05 mm, and the gap between the remaining adjacent stator tooth brackets is 0 mm.

[0029] Figure 2 The two axial rotor sections are shown to be skewed relative to each other at an angle a, which is calculated according to the following formula: Skew angle a = k*360 / Max (number of slots, number of poles) / n. In this example, k = 0.8, Max (number of slots, number of poles) is 12, and n is 2. Therefore, the skew angle = 12 degrees. Since there are 10 poles, the electrical angle is the number of pole pairs * 12, that is, 5*12 = 60 degrees.

[0030] When assembling the rotor, it can be assembled in the following manner: the rotor segment on the axial upper side is tilted in the counterclockwise direction by half the tilt angle, i.e. 6 degrees, and the rotor segment on the axial lower side is tilted in the clockwise direction by half the tilt angle, thereby making the two axial rotor segments tilted 12 degrees relative to each other.

[0031] Figure 3 Shows Figure 1 The stator and Figure 2The schematic diagram of the rotor assembly is shown in FIG. 1 , and the stator windings A1-A4, B1-B4 and C1-C4 have been installed in each tooth slot, wherein two windings opposite to each other in the diametric direction constitute one phase (i.e., two stator windings of the same phase are arranged 180 degrees apart in the circumferential direction), and the 12 stator windings constitute a total of 6 phases. These 6 phases are divided into two independent 3-phase systems, and the stator windings of the same phase system are arranged adjacent to each other in the circumferential direction. Figure 4A-4B The equivalent circuit diagrams of the two 3-phase systems are shown, wherein stator windings A1 and A3 constitute the U1 phase of the first phase system, stator windings B1 and B3 constitute the V1 phase, stator windings C1 and C3 constitute the W1 phase, stator windings A2 and A4 constitute the U2 phase of the second phase system, stator windings B2 and B4 constitute the V2 phase, and stator windings C2 and C4 constitute the W1 phase.

[0032] The first phase system is fed with current according to the formula Irms*1.414*sin(2π*f*t+b1), and the second phase system is fed with current according to the formula Irms*1.414*sin(2π*f*t+b2), where Irms is the effective value of the current, f is the current frequency, t is the time, b1 is the lagging phase shift angle of the first phase system relative to the back EMF zero position without phase shift, ranging from -10 to 13 degrees, and b2 is the leading phase shift angle of the second phase system relative to the back EMF zero position without phase shift, ranging from 15 to 18 degrees. The current waveform fed to the two phase systems is as follows: Figure 5 As shown, the vertical axis is the electric potential and the horizontal axis is the phase angle.

[0033] Figure 6 A comparison diagram showing the relationship between the skew angle and the cogging torque, motor output torque and torque pulsation reduction is shown. It can be seen from the figure that the phase shift angle set by the utility model compensates for the reduction of the motor output torque caused by the skew angle, and has the best cogging torque and torque pulsation reduction and motor output torque reduction at a skew angle of 12 degrees.

[0034] In some cases, the features disclosed in the present invention may be used independently of other features. On the other hand, when necessary, the features disclosed in the present invention may be combined to provide various combinations.

[0035] The words and expressions used in the present invention are illustrative rather than restrictive, and therefore the use of these words and expressions is not intended to exclude any equivalents of the features illustrated and described from the scope of the present invention. Various modifications, variations and alternatives may exist within the scope of the claims. The claims are intended to cover all such equivalents.

Claims

1. A motor rotor, wherein the rotor is equally divided into at least two axial rotor segments along the axial direction, and adjacent axial rotor segments are circumferentially deflected from each other by a deflection angle, characterized in that: The skew angle is set according to the following formula: skew angle = k*360 / Max (number of slots, number of poles) / n, where k = 0.75-0.85, Max (number of slots, number of poles) is the larger of the number of slots and the number of poles of the motor, and n is the number of axial rotor segments.

2. The motor rotor according to claim 1, characterized in that: The motor is a 12-slot 10-pole motor, the rotor is a two-section rotor, and the magnets are mounted on the outer circumferential surface of the rotor core.

3. The motor rotor according to claim 2, characterized in that: k＝0.8。 4. The motor rotor according to any one of claims 2-3, characterized in that: The axially upper axial rotor segment is tilted by half the tilt angle in the counterclockwise direction in the circumferential direction relative to the non-tilted arrangement of the two axial rotor segments, and the axially lower axial rotor segment is tilted by half the tilt angle in the clockwise direction in the circumferential direction relative to the non-tilted arrangement of the two axial rotor segments.

5. A segmented modular stator motor, characterized in that: The segmented modular stator motor comprises a motor rotor according to any one of claims 1-4.

6. The segmented modular stator motor according to claim 5, characterized in that: The electric machine further comprises a segmented modular stator which is equally divided into a plurality of stator segments in a circumferential direction, adjacent stator segments define tooth slots, and the stator windings are arranged in the tooth slots.

7. The segmented modular stator motor according to claim 6, characterized in that: Two stator windings that are diametrically opposite to each other constitute one phase.

8. The segmented modular stator motor according to claim 6 or 7, characterized in that: The stator winding is divided into a first and a second phase system, and the stator windings of the same phase system are arranged adjacent to each other in the circumferential direction.

9. The segmented modular stator motor according to claim 8, characterized in that: The motor is a 12-slot 10-pole motor.

10. The segmented modular stator motor according to claim 9, characterized in that: The motor also includes an electronic control unit, which is configured to feed current to the first and second phase systems according to the following formula: for the first phase system, Irms*1.414*sin(2π*f*t+b1), for the second phase system, Irms*1.414*sin(2π*f*t+b2), where Irms is the effective value of the current, f is the current frequency, t is the time, b1 is the lagging phase shift angle of the first phase system relative to the back-EMF zero position without phase shift, ranging from -10 to 13 degrees, and b2 is the advancing phase shift angle of the second phase system relative to the back-EMF zero position without phase shift, ranging from 15 to 18 degrees.

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