A magnetic gear with a multi-slot rotor and a magnetic gear composite motor

Abstract

The present invention discloses a magnetic gear and a magnetic gear composite motor with a multi-slot rotor, belonging to the field of power transmission technology. The magnetic gear comprises an inner rotor, a magnetic adjustment ring, and an outer rotor; an air gap is provided between the magnetic adjustment ring and both the inner and outer rotors; the inner rotor comprises an inner rotor yoke having N1 inner rotor magnetic steel slots uniformly distributed along the circumference on the outer side, and N1 inner rotor magnets embedded in the inner rotor magnetic steel slots; the magnetic adjustment ring comprises M magnetic conductive units uniformly distributed along the circumference; the outer rotor comprises an outer rotor yoke and N2 outer rotor magnets; the inner side of the outer rotor yoke comprises N2 outer rotor magnetic steel slots uniformly distributed along the circumference, and the outer side comprises N2 idle outer rotor slots, with the N2 outer rotor magnets respectively embedded in the N2 outer rotor magnetic steel slots; the centripetal axes of the corresponding slots on the inner and outer sides of the outer rotor coincide. The present invention can solve the problems of large structural losses, low efficiency, and high mass existing in traditional concentric magnetic gears and magnetic gear composite motors.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transmission, and more particularly, relates to a magnetic gear with a multi-slot rotor and a magnetic gear composite motor. Background Art

[0002] Unlike traditional mechanical gears, concentric magnetic gears have attracted widespread attention since their invention in the last century due to their frictionlessness, low noise, and built-in overload protection. Based on the principle of magnetic field modulation, concentric magnetic gears boast high permanent magnet utilization and torque density comparable to traditional mechanical gears, demonstrating promising industrial prospects.

[0003] As an energy transmission unit, the efficiency of magnetic gears is their key indicator. However, since concentric magnetic gears utilize the modulation principle, there are more non-working magnetic field harmonics in the air gap, which makes the non-working magnetic flux density in the core, especially the rotor yoke core, larger and changes faster, causing large eddy current loss and hysteresis loss, and low overall efficiency. This has led many scientific researchers to devote themselves to research on how to improve the efficiency of magnetic gears.

[0004] Concentric magnetic gears can be combined with permanent magnet synchronous motors to form a new type of motor, called a magnetic gear compound motor. Because of its embedded reduction magnetic gear, the magnetic gear compound motor's mechanical interface naturally exhibits the characteristics of "low speed, high torque," and has great application potential in direct-drive applications such as aerospace, oilfield development, electric traction, and renewable energy power generation. By sharing components, the magnetic gear compound motor can significantly reduce the size of the original "motor + gearbox" electric drive system. However, the magnetic gear compound motor also faces the efficiency issues of the concentric magnetic gear, and its losses, especially the iron loss in the rotor, need to be reduced urgently.

[0005] Patent document CN113949223A proposes a low-loss magnetic gear device that reduces end magnetic leakage by setting magnetic shielding rings at both ends of the rotor ring to improve the efficiency of the magnetic gear. However, this device can only reduce end magnetic leakage, and the effect will deteriorate as the axial length of the gear increases.

[0006] The patent document with application publication number CN116545211A proposes a magnetic gear specially designed for swapping magnetic rings. By increasing the sinusoidality of the spatial magnetic permeability distribution, the non-working magnetic density component of the yoke is reduced, thereby reducing losses and torque pulsation. Although this design reduces the higher harmonics of the magnetic permeability, it also reduces the fundamental component, which will have a significant impact on the torque density when the transmission is relatively small.

[0007] Patent document CN108683321A proposes a magnetic gear with a slotted outer rotor. Taking advantage of the magnetic field distribution characteristics under the Spoke polarization form, the excess part of the iron yoke is slotted to reduce the mass of the magnetic gear adopting radial-Spoke polarization. However, this invention does not change the distribution of magnetic lines of force in the magnetic gear, and therefore has almost no improvement on the average torque, torque ripple, and loss of the magnetic gear, and only reduces the mass.

[0008] Patent document CN111446840A proposes a method for reducing losses in a magnetic gear compound motor. Specifically, the method eliminates non-operating harmonic components by adjusting the winding pitch. Since the magnetic gear compound motor contains two layers of magnetic steel and a magnetic field modulation unit, the harmonics generated and modulated by the magnetic steel are very rich. The torque pulsation caused by these stray harmonics also needs to be suppressed urgently. The method of adjusting the winding pitch is not sufficient in this regard.

[0009] Based on this, existing concentric magnetic gears and magnetic gear composite motors have problems such as large structural loss, low efficiency, and large mass, making them difficult to apply in actual engineering. Summary of the Invention

[0010] In response to the defects of the existing technology and the need for improvement, the present invention provides a magnetic gear and a magnetic gear composite motor with a multi-slot rotor, the purpose of which is to solve the problems of large structural loss, low efficiency and large mass existing in traditional concentric magnetic gears and magnetic gear composite motors.

[0011] To achieve the above object, according to one aspect of the present invention, there is provided a magnetic gear having a multi-slot rotor, comprising: an inner rotor, a magnetic adjustment ring, and an outer rotor coaxially arranged from the inside outward; air gaps are provided between the inner rotor and the magnetic adjustment ring, and between the magnetic adjustment ring and the outer rotor;

[0012] The inner rotor includes an inner rotor yoke and N1 inner rotor magnets; the outer side of the inner rotor yoke is provided with N1 inner rotor magnet slots that match the shape of the inner rotor magnets and are evenly distributed along the circumference, and the N1 inner rotor magnets are respectively embedded in the N1 inner rotor magnet slots;

[0013] The magnetic tuning ring includes M magnetic conductive units evenly distributed along the circumference;

[0014] The outer rotor includes an outer rotor yoke and N2 outer rotor magnets; the inner side of the outer rotor yoke is provided with N2 outer rotor magnet slots that match the shape of the outer rotor magnets and are evenly distributed along the circumference, and the N2 outer rotor magnets are respectively embedded in the N2 outer rotor magnet slots; the outer side of the outer rotor yoke is provided with N2 outer rotor idle slots that correspond one-to-one to the N2 outer rotor magnet slots, and the corresponding outer rotor magnet slots and the outer rotor idle slots have their centripetal axes coincident;

[0015] Among them, N1, N2 and M are all positive integers, and N1 <N2。

[0016] Furthermore, N1 inner rotor idle slots corresponding to the N1 inner rotor magnetic steel slots are provided on the inner side of the inner rotor yoke, and the centripetal axes of the corresponding inner rotor magnetic steel slots and the inner rotor idle slots coincide with each other.

[0017] In some optional embodiments, the inner rotor idle slot is rectangular.

[0018] In some optional embodiments, the slots of the inner rotor magnet are arc-shaped, and the inner rotor magnet is a radially magnetized tile-shaped magnet.

[0019] In some optional embodiments, the outer rotor idle slot is rectangular.

[0020] In some optional embodiments, the slots of the outer rotor magnet are arc-shaped, and the outer rotor magnet is a radially magnetized tile-shaped magnet.

[0021] In some preferred embodiments, the idle slot of the outer rotor has a depth of aa=5 mm and a width of bb=5 mm; the idle slot of the inner rotor has a depth of cc=8 mm and a width of dd=5 mm.

[0022] In some optional embodiments, the material of the inner rotor yoke is electrical steel.

[0023] According to another aspect of the present invention, there is provided a magnetic gear compound motor, comprising a winding and the magnetic gear with a multi-slot rotor provided by the present invention;

[0024] The winding is arranged in the air gap inside the magnetic tuning ring.

[0025] In a traditional concentric magnetic gear structure, non-operating magnetic field harmonics form a magnetic flux path through the magnets and the air gap. The two main components are the few-pole magnetic field in the outer rotor, generated by the inner rotor magnets and unmodulated by the magnetic ring, and the multi-pole magnetic field in the inner rotor, generated by the outer rotor magnets and unmodulated by the magnetic ring. When the outer and inner rotors rotate at different speeds, these non-operating magnetic field harmonics, which do not contribute to torque, rotate differentially in the rotors, generating eddy current losses and hysteresis losses. The losses caused by the non-operating magnetic field are particularly significant in the outer rotor.

[0026] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0027] (1) The present invention sets an idle slot for the outer rotor on the outer side of the outer rotor yoke at a position corresponding to the slot for placing the outer rotor magnet, and the centripetal axes of the slot positions of the inner and outer slots coincide, so that the centripetal axis of the idle slot for the outer rotor just coincides with the d-axis of the corresponding magnet. Based on the setting of the idle slot for the outer rotor, the magnetic resistance of the working magnetic field that generates torque in the outer rotor remains unchanged, while the magnetic resistance of the non-working magnetic field that generates loss increases. This can weaken the eddy current loss and hysteresis loss generated by the non-working magnetic field while ensuring the torque of the magnetic gear, effectively improving the efficiency of the magnetic gear. At the same time, the slot setting can also effectively reduce the amount and mass of the iron core. Therefore, the present invention can effectively solve the problems of large structural loss, low efficiency and large mass existing in traditional concentric magnetic gears. When applied to magnetic gear composite motors, it can also effectively solve the problems of large structural loss, low efficiency and large mass existing in magnetic gear composite motors.

[0028] (2) In the preferred embodiment of the present invention, an inner rotor idle slot is further provided on the inner side of the inner rotor yoke at a position corresponding to the slot for placing the inner rotor magnet, and the centripetal axes of the slotted positions of the inner and outer slots coincide, so that the centripetal axes of the inner rotor idle slot just coincide with the d-axis of the corresponding magnet. Based on the provision of the inner rotor idle slot, the magnetic resistance of the working magnetic field that generates torque in the inner rotor remains unchanged, while the magnetic resistance of the non-working magnetic field that generates loss increases. This can reduce the eddy current loss and hysteresis loss generated by the non-working magnetic field while ensuring the torque of the magnetic gear, further improving the efficiency of the magnetic gear. At the same time, the design of the slotted inner rotor iron yoke further reduces the amount of iron core used and the mass of the magnetic gear.

[0029] (3) In the preferred embodiment of the present invention, the idle slots of the inner / outer rotors are rectangular, which can effectively reduce the difficulty of processing.

[0030] (4) In the preferred embodiment of the present invention, the magnetic steel slots of the inner / outer rotor are set to be arc-shaped, and the magnetic steel is a radially magnetized tile-shaped magnetic steel, which can increase the radial magnetic density of the air gap, reduce the intensive magnetic density of the air gap, increase the torque, and reduce the torque pulsation and noise.

[0031] (5) The magnetic gear compound motor provided by the present invention includes the magnetic gear with a multi-slot rotor provided by the present invention, which can not only suppress the non-working magnetic field induced by the inner and outer rotor magnetic steels, but also weaken the multi-pole non-working armature magnetic field generated by the winding and modulated in the inner rotor and the few-pole non-working armature magnetic field generated by the winding and not modulated in the outer rotor, thereby effectively suppressing the iron loss and magnetic steel loss of the magnetic gear compound motor and improving the efficiency of the magnetic gear compound motor. At the same time, the slotted design of the magnetic gear also reduces the overall mass of the magnetic gear compound motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1It is a schematic diagram of the traditional concentric magnetic gear structure;

[0033] Figure 2 A schematic diagram of the inner and outer rotor yokes in a magnetic gear structure with a multi-slot rotor provided by an embodiment of the present invention;

[0034] Figure 3 A schematic structural diagram of a magnetic gear with a multi-slot rotor provided in an embodiment of the present invention;

[0035] Figure 4 A partially enlarged schematic diagram of a magnetic gear with a multi-slot rotor provided by an embodiment of the present invention;

[0036] Figure 5 The magnetic field line distribution and magnetic density cloud diagram of the traditional concentric magnetic gear device;

[0037] Figure 6 The magnetic field line distribution and magnetic density cloud diagram of the magnetic gear with a multi-slot rotor provided in an embodiment of the present invention;

[0038] Figure 7 A line graph showing the maximum output torque of a magnetic gear with a multi-slot rotor according to an embodiment of the present invention as a function of the size of the idle slots;

[0039] Figure 8 A line graph showing how the iron loss of each part of a magnetic gear with a multi-slot rotor varies with the operating time of the magnetic gear provided in an embodiment of the present invention;

[0040] Figure 9 It is a schematic diagram of the structure of a traditional magnetic gear compound motor;

[0041] Figure 10 A schematic diagram of the structure of a magnetic gear compound motor provided in an embodiment of the present invention;

[0042] Figure 11 A schematic diagram of the three-phase no-load electromotive force of the windings in the magnetic gear compound motor provided by an embodiment of the present invention;

[0043] Figure 12 for Figure 9 The magnetic field line distribution and magnetic density cloud diagram of the traditional magnetic gear compound motor are shown;

[0044] Figure 13 for Figure 10 The magnetic field line distribution and magnetic density cloud diagram of the magnetic gear compound motor shown;

[0045] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0046] 1-inner rotor, 11-inner rotor magnet, 12-conventional inner rotor yoke, 13-multi-slot inner rotor yoke, 2-magnetic adjustment ring, 3-outer rotor, 31-outer rotor magnet, 32-conventional outer rotor yoke, 33-multi-slot outer rotor yoke, 4-winding. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0048] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0049] Before explaining the technical solution of the present invention in detail, the structure of a conventional concentric magnetic gear motor and the generation principle of the working magnetic field and the non-working magnetic field are briefly analyzed as follows.

[0050] Traditional concentric magnetic gear structure such as Figure 1 As shown, the inner rotor 1 includes an inner rotor, a magnetic ring 2, and an outer rotor 3. The inner rotor 1 includes inner rotor magnets 11 and a conventional inner rotor yoke 12, and the outer rotor 3 includes outer rotor magnets 31 and a conventional outer rotor yoke 32. The number of magnetic pole pairs of the inner rotor is smaller than that of the outer rotor. Therefore, the inner rotor can also be called a few-pole inner rotor, and correspondingly, the outer rotor can also be called a multi-stage outer rotor.

[0051] based on Figure 1 In the structure shown in the figure, in the absence of a magnetic ring, if the magnetic steel of one of the inner and outer rotors acts alone, a spatial magnetic field distribution can be generated in the air gap, and its radial component B r0 and the tangential component B θ0 Respectively expressed as:

[0052]

[0053] Where p is the number of rotor permanent magnet pole pairs, b is ri is the Fourier coefficient of the i-th harmonic radial magnetic flux density component when there is no magnetic ring, b θi is the Fourier coefficient of the tangential magnetic flux density component of the i-th harmonic when there is no magnetic ring. r represents the radius in the polar coordinate system, θ represents the angle in the polar coordinate system, t represents time, and Ω r represents the rotor mechanical angle, and θ0 represents the initial position of the rotor.

[0054] After the magnetic tuning ring structure is introduced, the magnetic permeance in the air gap will change. The relative magnetic permeance is defined as the ratio of the magnetic permeance of the air gap with and without the magnetic tuning ring, denoted as λ, which can be decomposed into the Fourier transform:

[0055]

[0056] Where, M is the number of poles of the magnetic adjustment ring, Ω m is the mechanical rotation speed of the magnetic ring, λ0 represents the constant term of the specific magnetic permeability, λ j represents the jth harmonic of the specific permeability;

[0057] After the magnetic tuning ring is introduced, the air gap magnetic field generated by the rotor magnetic steel after the magnetic tuning ring modulates the space magnetic field should be:

[0058] B(r,θ)=B0(r,θ)·λ (3)

[0059] Where B0 represents the magnetic flux density when there is no magnetic ring. Substituting formulas (1) and (2) into formula (3), we get:

[0060]

[0061]

[0062] Among them, λ rj is the Fourier coefficient of the modulation function of the jth harmonic of the magnetic ring on the radial magnetic flux density component, λ θj is the Fourier coefficient of the modulation function of the jth harmonic of the magnetic tuning ring on the tangential magnetic flux density component. From formulas (4) and (5), it can be seen that no matter whether it is the spatial magnetic field generated by the inner rotor magnet or the outer rotor magnet, under the action of the magnetic tuning ring, the pole pair number of the newly generated spatially distributed magnetic field harmonic is expressed as follows:

[0063] p m,j =|mp+jM|,m=1,3,5...; j=0,±1,±2,±3,... (6)

[0064] The speed of this harmonic is:

[0065]

[0066] Formula (7) shows that after the introduction of the magnetic modulation ring, the spatial magnetic field generated by any rotor will generate a harmonic magnetic field with different speeds and pole pairs in the opposite air gap after being modulated by the magnetic modulation ring. In order to maximize the output torque of the concentric magnetic gear, the spatial magnetic field harmonic with the largest amplitude after being modulated by the magnetic modulation ring should be taken as the working harmonic. Generally speaking, since the higher the harmonic order, the lower the harmonic amplitude, m = 1 and j = -1 are selected. At this time, the modulated spatial magnetic field harmonic amplitude is the largest. That is, when the permanent magnet pole pair number of one rotor is p, the permanent magnet pole pair number of the other rotor should be |pM|, generally Mp.

[0067] However, although the number of working magnetic field pole pairs in the air gap is Mp, non-working magnetic field harmonics of other pole pairs still pass through the magnets and the air gap to form a magnetic flux path. For a conventional concentric magnetic gear structure, the two main components are the few-pole magnetic field generated by the few-pole rotor magnets in the multi-pole outer rotor and not modulated by the magnetic ring, and the multi-pole magnetic field generated by the multi-pole rotor magnets in the few-pole inner rotor and not modulated by the magnetic ring. When the outer and inner rotors rotate at different speeds, the non-working magnetic field harmonics that do not contribute to the torque will rotate differentially in the rotor, generating eddy current losses and hysteresis losses.

[0068] There are two main ways to reduce iron loss:

[0069] 1) Reduce the thickness of the permanent magnet to reduce the magnetomotive force, but this also weakens the working magnetic field and reduces the magnetic gear torque;

[0070] 2) Increasing the thickness of the yoke to increase the magnetic permeance, but this will increase the outer diameter of the magnetic gear, increasing its mass and volume.

[0071] Existing conventional methods for reducing iron loss will reduce the torque density of the magnetic gear. The fundamental reason is that the working magnetic field and non-working magnetic field in the magnetic gear cannot be separated. While weakening the non-working magnetic field, the working magnetic field will also be significantly weakened, which will damage the torque of the magnetic gear.

[0072] In conventional magnetic gear compound motors, the windings are arranged in slots formed in the magnetic tuning ring, such as Figure 9 As shown, the number of winding pole pairs is equal to the number of inner rotor pole pairs, so that it can drive the inner rotor to rotate, and then drive the outer rotor to rotate. Due to the natural "deceleration and torque increase" characteristics of the magnetic gear, the magnetic gear compound motor can have the "low speed and high torque" load direct drive mechanical characteristics on the outer rotor.

[0073] In conventional magnetic gear compound motors, the main components of the non-working magnetic flux density include not only the modulated multipole magnetic field generated by the magnets on the multipole outer rotor in the few-pole inner rotor brought by the magnetic gear itself, and the unmodulated few-pole magnetic field generated by the few-pole inner rotor in the multipole outer rotor, but also the non-working armature magnetic flux density harmonics introduced by the windings introduced into the magnetic modulation ring. Specifically, these include the modulated multipole magnetic field generated by the windings in the few-pole inner rotor and the unmodulated few-pole magnetic field generated by the armature in the multipole outer rotor. These four non-working magnetic flux density harmonics are the main sources of iron loss and magnetic steel loss in magnetic gear compound motors and are the main reason for reducing the efficiency of magnetic gear compound motors.

[0074] In order to solve the problems of large structural loss, low efficiency and large mass existing in traditional concentric magnetic gears and gear compound motors, the present invention provides a magnetic gear and a magnetic gear compound motor with a multi-slot rotor. The overall idea is to improve the magnetic gear structure based on the principle of the generation of working magnetic field and non-working magnetic field in concentric magnetic gears, so that the improved structure can increase the magnetic resistance of the non-working magnetic field without affecting the working magnetic field, thereby achieving the effect of suppressing the magnetic flux density of the non-working magnetic field, thereby reducing losses and improving efficiency.

[0075] The following are examples.

[0076] Example 1:

[0077] A magnetic gear having a multi-slot rotor, such as Figure 2 、 Figure 3 and Figure 4 As shown, it comprises: an inner rotor 1, a magnetic adjustment ring 2 and an outer rotor 3 which are coaxially arranged from the inside to the outside; air gaps are provided between the inner rotor 1 and the magnetic adjustment ring 2, and between the magnetic adjustment ring 2 and the outer rotor 3;

[0078] The inner rotor 1 includes an inner rotor yoke 13 and N1 inner rotor magnets 11. The outer side of the inner rotor yoke 13 is provided with N1 inner rotor magnet slots that match the shape of the inner rotor magnets 11 and are evenly distributed along the circumference. The N1 inner rotor magnets 11 are respectively embedded in the N1 inner rotor magnet slots. The inner side of the inner rotor yoke 13 is provided with N1 inner rotor idle slots that correspond one-to-one with the N1 inner rotor magnet slots. The centripetal axes of the corresponding inner rotor magnet slots and the inner rotor idle slots coincide.

[0079] The magnetic tuning ring 2 includes M magnetic conductive units evenly distributed along the circumference;

[0080] The outer rotor 3 includes an outer rotor yoke 33 and N2 outer rotor magnets 31. The inner side of the outer rotor yoke 33 is provided with N2 outer rotor magnet slots that match the shape of the outer rotor magnets 31 and are evenly distributed along the circumference. The N2 outer rotor magnets 31 are respectively embedded in the N2 outer rotor magnet slots. The outer side of the outer rotor yoke 33 is provided with N2 outer rotor idle slots that correspond one-to-one to the N2 outer rotor magnet slots. The corresponding outer rotor magnet slots and the outer rotor idle slots have their centripetal axes coincident.

[0081] Among them, N1, N2 and M are all positive integers, and N1 <N2。

[0082] Unlike traditional concentric magnetic gears, the magnetic gear with a multi-slot rotor provided in this embodiment has idle slots in addition to slots for placing magnets on the iron yokes of the inner and outer rotors, so that the iron yokes of the inner and outer rotors are both circular rings with multiple slots on the inner and outer sides, and the slots are evenly distributed on the inner and outer sides of the iron yoke ring. The number of slots on both sides is equal, and the centripetal axes of the slot positions on both sides coincide. The size and shape of the slots on both sides are not required to be equal, but the shape and size of the slots on each side are the same; the inner rotor magnets are embedded in the slots on the outer side of the inner rotor yoke, and the outer rotor magnets are embedded in the slots on the inner side of the outer rotor, forming a stable embedded excitation rotor structure: for both the inner and outer rotors, the number of magnets is exactly half of the number of slots, that is, the number of slots in the rotor is exactly 4 times the number of magnet pole pairs, and the d axis of each magnet coincides with the slot axis. The idle slots provided in the inner and outer rotors play a "magnetic blocking" role on the non-working magnetic flux.

[0083] Non-working magnetic flux density specifically refers to the unmodulated multi-pole magnetic field generated by the magnets on the multi-pole outer rotor in the few-pole inner rotor and the unmodulated few-pole magnetic field generated by the magnets on the few-pole inner rotor in the multi-pole outer rotor. Both are the main sources of iron loss and magnetic steel loss in conventional magnetic gears, and are also the main reason for the reduction in magnetic gear efficiency.

[0084] Figure 5 The figure shows the magnetic field line distribution and magnetic density cloud diagram of the traditional concentric magnetic gear. Figure 6 Shown are the magnetic force line distribution and magnetic density cloud diagram of the magnetic gear with a multi-slot rotor provided by an embodiment of the present invention. Figure 5 In the case of a rotor, half of the outer rotor contains an obvious minority-pole non-working magnetic field. The change of this magnetic field in the outer rotor only produces eddy current loss and hysteresis loss, but does not produce transmission torque, which is meaningless. Figure 6In the example, since the idle slots are only placed at the axis of the magnet, they have no effect on the working magnetic field circuit driven by the inner and outer rotor magnets. Their magnetic flux passes smoothly and couples with each other in the air gap to generate torque. However, for the non-working magnetic field, the introduction of the idle slots causes multiple air regions with extremely low magnetic permeability to appear in the magnetic circuit, resulting in a long magnetic circuit, large magnetic resistance, blocked magnetic lines of force, and suppressed magnetic flux density. Figure 5 and Figure 6 It can be clearly observed that in the magnetic gear with a multi-slot rotor provided by this embodiment, the magnetic lines of force in the non-operating magnetic field are "squeezed" to be smaller and longer, while the operating magnetic field remains virtually unchanged. This means that the multi-slot rotor structure can maintain the torque density of the magnetic gear while reducing its losses. In other words, the specially designed multi-slot rotor structure proposed in this embodiment maintains the reluctance of the torque-generating working magnetic field while increasing the reluctance of the loss-generating non-operating magnetic field. This reduces unnecessary eddy current and hysteresis losses while maintaining the torque of the magnetic gear, thereby improving efficiency. Furthermore, the increased number of slots reduces the amount and quality of silicon steel used in the magnetic gear, achieving both high efficiency and lightweight design.

[0085] Preferably, if Figures 2-4 As shown, in this embodiment, the idle slots of the inner rotor and the outer rotor are both rectangular, thereby reducing processing difficulty. The slots of the inner rotor magnetic steel and the outer rotor magnetic steel are both arc-shaped, and the inner rotor magnetic steel and the outer rotor magnetic steel are both radially magnetized tile-shaped magnets. This can increase the radial flux density of the air gap and reduce the tangential flux density of the air gap, thereby increasing torque and reducing torque ripple and noise. It should be noted that the description of the slot shape here is only a preferred embodiment and should not be construed as the sole limitation of the present invention. In other embodiments of the present invention, the slots on the inner and outer rotors may also be configured in other shapes.

[0086] Optionally, in this embodiment, the inner rotor yoke is made of electrical steel to further enhance the mechanical strength and reduce the cost of the magnetic gear.

[0087] N1, N2 and M satisfy the magnetic field modulation relationship. In practical applications, they can be set accordingly according to the required motor performance. i =2, number of outer rotor pole pairs p o =7, then the number of slots in the inner and outer rotors are 8 and 28 respectively, and the number of magnet blocks in the magnetic adjustment ring is 9. Figures 2 to 4 This embodiment further optimizes the geometric parameters of the idle slots, including the depth aa and width bb of the outer rotor idle slots, and the depth cc and width dd of the inner rotor idle slots. Figure 1 The conventional concentric magnetic gear shown is used as the optimization object, and its dimensional parameters are shown in Table 1.

[0088] Table 1 Dimensional parameters of traditional concentric magnetic gears

[0089]

[0090]

[0091] The maximum output torque of the magnetic gear varies with the idle slot depth aa and width bb of the outer rotor yoke as shown in the following figure: Figure 7 As shown in the figure, the iron loss of the magnetic gear outer rotor varies with the idle slot depth aa and width bb of the outer rotor yoke. Figure 8 shown; according to Figure 7 and Figure 8 It can be seen that as the width and depth of the idle slots of the outer rotor increase, the iron loss of the outer rotor decreases significantly, but the decrease in the output torque is very small. The reason is that the multi-slot rotor structure proposed in this embodiment can specifically reduce the non-working magnetic flux that causes loss, while retaining the working magnetic flux that contributes to the torque as much as possible.

[0092] Ultimately, the optimized parameters selected for this embodiment are: outer idle slot depth aa = 5mm, width bb = 5mm; inner idle slot depth cc = 8mm, width dd = 5mm. Compared to conventional magnetic gears, the maximum output torque is 20.74 Nm, a 7.2% reduction. The outer rotor iron loss is 2.99 W, a 53.0% reduction. The total loss is 5.71 W, a 41.7% reduction, and the efficiency is 99.5%.

[0093] In addition, the cross-sectional area of ​​the outer rotor yoke and the inner rotor yoke are 1408.4mm 2 and 802.5mm 2 , which are respectively reduced by 20.5% and 14.4% compared with conventional concentric magnetic gears, thus reducing the amount of magnetic gear core used and making it lighter.

[0094] It should be noted that slotting the rotor yoke inevitably reduces the maximum output torque. This embodiment employs a special design for the slot locations to minimize the impact on maximum output torque. In practical applications, the output torque required by magnetic gears is often less than the maximum output torque. Therefore, the magnetic gear device provided in this embodiment can meet actual torque application requirements while significantly reducing gear mass and losses.

[0095] In general, this embodiment can significantly reduce the iron loss on the inner and outer rotors of the concentric magnetic gear while ensuring that the torque density remains almost unchanged, thereby improving its transmission efficiency and reducing the amount and weight of the iron core, thereby achieving lightweight and high efficiency of the concentric magnetic gear, and has good engineering practical value.

[0096] Example 2:

[0097] A magnetic gear with a multi-slot rotor. This embodiment is similar to the above-mentioned embodiment 1, except that, in this embodiment, only the outer side of the outer rotor is provided with idle slots, while the inner side of the inner rotor is not provided with restrictive slots.

[0098] When the outer and inner rotors rotate at different speeds, non-operating magnetic field harmonics that do not contribute to torque rotate differentially in the rotors, generating eddy current and hysteresis losses. Losses due to the non-operating magnetic field are particularly pronounced in the outer rotor. This embodiment, which only provides idle slots on the outer rotor, significantly reduces iron loss on the outer rotor of a concentric magnetic gear while maintaining nearly unchanged torque density, improving transmission efficiency and reducing the amount and weight of the core. This achieves lightweight and efficient concentric magnetic gears, demonstrating excellent engineering value.

[0099] Example 3:

[0100] A magnetic gear compound motor, such as Figure 10 As shown, it includes a winding and a magnetic gear with a multi-slot rotor provided in the above embodiment 1;

[0101] The winding is arranged in the air gap inside the magnetic tuning ring.

[0102] Since the number of magnetic pole pairs of the inner rotor in the magnetic gear is p i =2, number of outer rotor pole pairs p o =7, so the number of slots in the magnetic gear compound motor is S=p i +p o =9. Preferably, this embodiment adopts a double-layer fractional slot winding to form a slot-pole matching scheme of 9 slots and 4 poles. The corresponding three-phase current is passed through the winding to drive the inner rotor to rotate at high speed. The high-speed rotating inner rotor drives the outer rotor to rotate at low speed. The three-phase no-load electromotive force of the winding is as follows: Figure 11 As shown, Figure 11 The feasibility of the magnetic gear compound motor proposed in this embodiment is proved.

[0103] Figure 12 The magnetic field line distribution and magnetic density cloud diagram of the traditional magnetic gear compound motor are shown below. Figure 13 The figure shows the magnetic force line distribution and magnetic density cloud diagram of the magnetic gear compound motor provided in this embodiment; Figure 12 and Figure 13It is clear that the magnetic gear in the magnetic gear compound motor provided in this embodiment, which is the magnetic gear with a multi-slot rotor provided in the first embodiment, not only inherits the advantage of suppressing the non-operating magnetic field induced by the two layers of magnetic steel in the multi-slot inner and outer rotor magnetic gears, but also reduces the modulated multi-pole non-operating armature magnetic field generated by the windings in the small-pole inner rotor and the unmodulated small-pole non-operating armature magnetic field generated by the windings in the multi-pole outer rotor. Therefore, it can suppress the iron loss and magnetic steel loss of the magnetic gear compound motor, thereby improving the efficiency of the magnetic gear compound motor.

[0104] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic gear having a multi-slot rotor, characterized in that: include: An inner rotor, a magnetic regulating ring and an outer rotor are coaxially arranged in sequence from the inside to the outside; An air gap is provided between the inner rotor and the magnetic adjustment ring, and between the magnetic adjustment ring and the outer rotor; The inner rotor includes an inner rotor yoke and N 1 inner rotor magnet; the outer side of the inner rotor yoke is provided with magnets that match the shape of the inner rotor magnet and are evenly distributed along the circumference. N 1 inner rotor magnetic steel slot, N 1 inner rotor magnet is embedded in the N 1 inner rotor magnet slot; The magnetic tuning ring includes M Magnetic conductive units evenly distributed along the circumference; The outer rotor includes an outer rotor yoke and N 2 outer rotor magnets; the inner side of the outer rotor yoke is provided with magnets that match the shape of the outer rotor magnets and are evenly distributed along the circumference. N 2 outer rotor magnetic steel slots, the N The two outer rotor magnets are embedded in the N 2 outer rotor magnetic steel slots; the outer side of the outer rotor yoke is provided with N The two outer rotor magnetic steel slots correspond one to one N Two idle slots of the outer rotor, the corresponding outer rotor magnetic steel slots and the centripetal axes of the outer rotor idle slots coincide with each other; The inner side of the inner rotor yoke is also provided with N 1 inner rotor magnetic steel slots correspond one to one N 1 inner rotor idle slot, the corresponding inner rotor magnetic steel slot and the inner rotor idle slot have their centripetal axes coincident; in, N 1. N 2 and M are all positive integers, and N 1< N 2.

2. The magnetic gear with a multi-slot rotor according to claim 1, wherein: The inner rotor idle slot is rectangular.

3. The magnetic gear with a multi-slot rotor according to claim 2, wherein: The inner rotor magnetic steel slot is arc-shaped, and the inner rotor magnetic steel is a radially magnetized tile-shaped magnetic steel.

4. The magnetic gear with a multi-slot rotor according to claim 2, wherein: The outer rotor idle slot is rectangular.

5. The magnetic gear with a multi-slot rotor according to claim 4, wherein: The outer rotor magnetic steel slot is arc-shaped, and the outer rotor magnetic steel is a radially magnetized tile-shaped magnetic steel.

6. The magnetic gear with a multi-slot rotor according to claim 5, wherein: The idle slot of the outer rotor has a depth of aa=5mm and a width of bb=5mm; the idle slot of the inner rotor has a depth of cc=8mm and a width of dd=5mm.

7. The magnetic gear with a multi-slot rotor according to any one of claims 1 to 6, wherein: The inner rotor yoke is made of electrical steel.

8. A magnetic gear compound motor, characterized in that: comprising a winding and a magnetic gear with a multi-slot rotor as claimed in any one of claims 1 to 7; The winding is arranged in the air gap inside the magnetic tuning ring.

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