A magnetic steel, an electric machine rotor and an axial magnetic field electric machine

Abstract

The application discloses a magnetic steel, which comprises a magnetic conductive layer group and a magnet layer arranged on both sides of the magnetic conductive layer group, and the relative permeability of the magnetic conductive layer group is greater than that of the magnet layer. Compared with the prior art, the thickness of the magnet layer is reduced, and the magnetic conductive layer group with high relative permeability is added, so that the internal magnetic resistance of the whole magnetic steel can be greatly reduced under the premise of guaranteeing the original magnetic field intensity of the magnetic steel, the motor working efficiency is kept high, the amount of the magnet material can be effectively reduced, the utilization rate of the magnetic steel material is improved, and the motor manufacturing cost is reduced. The application further discloses a motor rotor comprising the magnetic steel and an axial magnetic field motor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor design, in particular to a magnetic steel, a motor rotor and an axial magnetic field motor. BACKGROUND

[0002] The axial magnetic field motor is composed of a stator and a rotor, wherein the stator is provided with windings, and the rotor is provided with magnetic steels, the magnetic steels are oppositely arranged with the windings to interact with each other. When designing a large-torque axial magnetic field motor, a larger rotor disc needs to be provided to provide a larger magnetic force, therefore, the effective outer diameter of the motor also needs to be increased in design. When the rotor disc is increased in design, the thickness of the rotor disc also needs to be increased accordingly to maintain the required rigidity and strength of the rotor disc. When the thickness of the rotor disc is increased, the thickness of the magnetic steels also needs to be increased to ensure the gap between the magnetic steels and the coils. When the thickness of the magnetic steels is increased, the internal magnetic resistance of the magnetic steels is also multiplied, which will seriously affect the utilization efficiency of the magnetic steels. The principle is that according to the full-circuit Ohm's law: I = U / (R + r), I is the current in the circuit, U is the voltage, R is the external load resistance, and r is the internal resistance of the power supply. The size of the voltage across the power supply is affected by the internal resistance of the power supply. The magnetic circuit has similarity with the electric circuit, Φ = F / (Rδ + rδ), wherein F is the magnetic motive force of the magnetic steels, rδ is the internal magnetic resistance of the magnetic steels, i.e. the internal resistance of the magnetic steels. The internal magnetic resistance rδ of the magnetic steels = μh / s, h is the thickness of the magnetic steels, μ is the magnetic permeability of the magnetic steels, which is equivalent to the magnetic permeability of air, and s is the width of the magnetic steels. It can be seen from the formula that the greater the h is, the greater the internal magnetic resistance of the magnetic steels is.

[0003] When the size of the motor is continuously increased, the internal magnetic resistance of the neodymium-iron-boron magnetic steels begins to become prominent, which will affect the working efficiency of the motor and cause a large amount of heat.

[0004] Therefore, how to reduce the internal magnetic resistance of the magnetic steels while maintaining a high working efficiency of the motor is a technical problem to be solved by those skilled in the art at present. SUMMARY

[0005] Therefore, the present application aims to provide a magnetic steel for reducing the internal magnetic resistance of the magnetic steels, improving the utilization rate of the magnetic material, reducing the manufacturing cost of the motor, and maintaining a high working efficiency of the motor. Another object of the present application is to provide a motor rotor comprising the above-mentioned magnetic steel and an axial magnetic field motor.

[0006] In order to achieve the above-mentioned objects, the present application provides the following technical solutions.

[0007] A magnetic steel comprises a group of magnetic conductive layers and a magnetic layer sandwiched between the two sides of the group of magnetic conductive layers, the relative magnetic permeability of the group of magnetic conductive layers is greater than the relative magnetic permeability of the magnetic layer.

[0008] Preferably, the thickness of the group of magnetic conductive layers is 1 / 4 to 1 / 3 of the total thickness of the magnetic steel.

[0009] Preferably, the group of magnetic conductive layers comprises one layer of magnetic conductive layer or at least two layers of the magnetic conductive layers arranged in a stack.

[0010] Preferably, the magnetic iron layer is arranged between at least two adjacent layers of the magnetic conductive layers or directly contacts any two adjacent layers of the magnetic conductive layers.

[0011] Preferably, the material of each layer of the magnetic conductive layers is the same or different, or the material of part of the layers of the magnetic conductive layers is the same.

[0012] The material of each layer of the magnetic iron layers is the same or different, or the material of part of the layers of the magnetic iron layers is the same.

[0013] Preferably, the thickness of each layer of the magnetic conductive layers is the same or different, or the thickness of part of the layers of the magnetic conductive layers is the same.

[0014] The thickness of each layer of the magnetic iron layers is the same or different, or the thickness of part of the layers of the magnetic iron layers is the same.

[0015] Preferably, the material of the magnetic iron layer is neodymium iron boron or ferrite, and the material of the magnetic conductive layer is silicon steel, low carbon steel or pure iron.

[0016] Preferably, the magnetic iron layer and the group of magnetic conductive layers are fixed by magnetic force, and / or the magnetic iron layer and the group of magnetic conductive layers are provided with fixing glue.

[0017] The magnetic steel provided by the application comprises a group of magnetic conductive layers and magnetic iron layers arranged on both sides of the group of magnetic conductive layers, and the relative magnetic permeability of the group of magnetic conductive layers is greater than that of the magnetic iron layers. Compared with the prior art, the thickness of the magnetic iron layer is reduced, and the group of magnetic conductive layers with high relative magnetic permeability is added. Therefore, the internal magnetic resistance of the entire magnetic steel can be greatly reduced under the premise of ensuring the original magnetic field strength of the magnetic steel, so that the working efficiency of the motor is maintained, the amount of magnetic iron material is effectively reduced, the utilization rate of the magnetic steel material is improved, and the manufacturing cost of the motor is reduced.

[0018] The application further provides a motor rotor comprising the magnetic steel described above. The derivation process of the beneficial effects of the motor rotor is similar to that of the magnetic steel, and thus will not be described herein.

[0019] Preferably, the motor rotor further comprises a magnetic steel holder for fixing the magnetic steel.

[0020] The application also provides an axial magnetic field motor comprising the motor rotor as described above. The derivation process of the beneficial effects of the axial magnetic field motor is similar to that of the magnetic steel, and thus is not described herein. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0022] Figure 1 Structure diagram of the motor rotor and the magnetic steel in the first embodiment of the present application.

[0023] Figure 2 Full circuit diagram to which Ohm's law is applicable.

[0024] Figure 1 The meanings of the reference signs in the drawings are as follows:

[0025] 1-magnetic steel holder, 2-magnet layer, 3-magnetic conductive layer group. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application.

[0027] Please refer to Figure 1 In order to reduce the amount of magnet material of the magnetic steel and the manufacturing cost of the motor, the present application provides a magnetic steel, which comprises a magnetic conductive layer group 3 and magnet layers 2 sandwiched between the two sides of the magnetic conductive layer group 3, and the relative magnetic permeability of the magnetic conductive layer group 3 is greater than that of the magnet layers 2. Compared with the prior art, the thickness of the magnet layers 2 is reduced, and the magnetic conductive layer group 3 with high relative magnetic permeability is added, so that the internal magnetic resistance of the entire magnetic steel can be greatly reduced under the premise of ensuring the original magnetic field strength of the magnetic steel, thereby maintaining high motor efficiency, the amount of magnet material can be effectively reduced, the utilization rate of the magnetic steel is improved, and the manufacturing cost of the motor is reduced.

[0028] The present application adds the magnetic conductive layer group 3 between the two magnet layers 2, i.e., replaces part of the magnet material with magnetic conductive material, so that the internal magnetic resistance of the entire magnetic steel can be greatly reduced. The principle is that please refer to Figure 2According to Ohm's law for the entire circuit: I = U / (R + r), where I is the current in the circuit and U is the voltage. Figure 2 In this scheme, the electromotive force (E) is given, R is the external load resistance, and r is the internal resistance of the power supply. It is evident that the voltage across the power supply is affected by its internal resistance. The magnetic circuit in this scheme is similar to the electrical circuit. In Ohm's law for magnetic circuits: Φ = F / (Rδ + rδ), where F is the magnetomotive force of the magnet; rδ is the magnetic reluctance of the magnet; rδ = μh / s, where h is the thickness of the magnet, μ is the permeability of the magnet (comparable to the permeability of air), and s is the width of the magnet. From the formula, it can be seen that the larger h is, the greater the internal resistance of the magnet. Reducing h can decrease the internal resistance of the magnet. This scheme reduces the thickness h of the original magnet material by adding a layer of magnetically conductive material between the original magnet material layers. Since the internal resistance of the magnetically conductive material layer is much smaller than that of the original magnet material, this scheme can reduce the overall internal magnetic reluctance of the magnet.

[0029] It should be noted that the magnetic conductive layer group 3 may include only one magnetic conductive layer, or it may include at least two magnetic conductive layers arranged in a stacked manner.

[0030] It should be noted that when the magnetic conductive layer group 3 includes two or more layers of magnetic conductive layers stacked together, a magnet layer 2 can also be provided between the magnetic conductive layers. Specifically, a magnet layer 2 is provided between at least one pair of adjacent magnetic conductive layers, that is, a magnet layer is provided between at least two adjacent magnetic conductive layers. Of course, this solution can also omit the magnet layer 2 between the magnetic conductive layers. Specifically, any two adjacent magnetic conductive layers are in direct contact, that is, any two adjacent magnetic conductive layers are in direct contact.

[0031] It should be noted that the aforementioned magnetic conductive layers can be made of the same material or different materials, or some magnetic conductive layers can be made of the same material. Similarly, the aforementioned magnet layers 2 can be made of the same material or different materials, or some magnet layers 2 can be made of the same material. Preferably, the magnet layer 2 in this solution is made of commonly used permanent magnet materials such as neodymium iron boron or ferrite, and the magnetic conductive layer is made of common magnetic conductive materials such as silicon steel, low-carbon steel, or pure iron.

[0032] It should be noted that the thickness of each of the above-mentioned magnetic conductive layers can be designed to be the same thickness or to be unequal, or some of the magnetic conductive layers may have the same thickness. The thickness of each of the above-mentioned magnet layers 2 can be designed to be the same thickness or to be unequal, or some of the magnet layers 2 may have the same thickness.

[0033] It should be noted that when designing the thickness of the magnet layer 2 and the thickness of the magnetic conductive layer, the power and torque of different motors and the overall thickness of the magnetic steel should be considered. The greater the torque of the motor, the greater the volume of the motor. For an axial magnetic field motor, as the torque increases, the effective outer diameter of the motor also increases. Due to the lengthening of the magnetic circuit and the consideration of the axial stiffness of the rotor disc, the rotor magnetic steel also thickens. In the three-layer structure of the magnetic steel, preferably, the thickness of the two magnet layers 2 is equal. In the magnetic steel structure comprising at least two magnet layers 2 and at least two magnetic conductive layers, preferably, the thickness of each magnet layer 2 is equal, and the thickness of each magnetic conductive layer is also equal.

[0034] Preferably, the thickness of the magnetic conductive layer group 3 is 1 / 4 to 1 / 3 of the total thickness of the magnetic steel. This will be described in subsequent embodiments.

[0035] It should be noted that the magnet layer 2 in the present scheme can be fixed with the magnetic conductive layer group 3 in various ways. Preferably, the magnet layer 2 and the magnetic conductive layer group 3 are fixed by magnetic force. Further preferably, a fixing glue is provided between the magnet layer 2 and the magnetic conductive layer group 3, that is, the fixing is achieved by gluing and magnetic attraction.

[0036] The differences between the present scheme and the prior art scheme will be described in the following embodiments and comparative examples.

[0037] Embodiment 1

[0038] In embodiment 1, the magnetic steel comprises a three-layer structure, that is, the magnetic steel comprises two magnet layers 2 and a magnetic conductive layer group 3 sandwiched between the two magnet layers 2, as shown in Figure 1 Specifically, the material of the magnet layer 2 is neodymium iron boron, and the magnetic conductive layer group 3 (i.e. the magnetic conductive material layer) is specifically a silicon steel sheet. The magnetic steel is in order of neodymium iron boron layer, magnetic conductive material layer and neodymium iron boron layer along the thickness direction, and the magnetic permeability of neodymium iron boron is much smaller than that of the magnetic conductive material layer. The relative magnetic permeability of the silicon steel sheet is 7000-10000, and the relative magnetic permeability of neodymium iron boron is 1, wherein the relative magnetic permeability refers to the ratio of the magnetic permeability of a certain substance to the magnetic permeability of vacuum, and the magnetic permeability of vacuum is 4×3.14×10^(-7).

[0039] The thickness of the magnetic conductive layer group 3 in the present scheme is 1 / 4 of the total thickness of the magnetic steel, the thickness of the magnetic steel is 12mm, the thickness of the magnetic conductive material layer (silicon steel sheet) is 3mm, and the thickness of the two neodymium iron boron layers is 4.5mm respectively. At this time, the relative internal resistance of the magnetic steel is 0.75R0, the simulation test data shows that the motor line current effective value is 110A, the motor torque is 164.8N·m, and the motor efficiency is 96.30%.

[0040] Embodiment 2

[0041] In this embodiment, the magnetic steel is still designed as a three-layer structure, including two layers of neodymium iron boron material and a layer of magnetic conductive material in the middle, wherein the magnetic conductive material is a silicon steel sheet, the rotor disc thickness (i.e. the thickness of the magnetic steel) is 12 mm, and the thicknesses of the front and rear two layers of neodymium iron boron material are the same. The difference between Example 2 and Example 1 is that: the thickness of each layer of neodymium iron boron material is 4 mm, the thickness of the layer of magnetic conductive material is 4 mm, and the thickness of the layer of magnetic conductive material is 1 / 3 of the total thickness of the magnetic steel. At this time, the relative internal resistance of the magnetic steel is 0.667R0. Simulation test data shows that the motor line current effective value is 110 A, the motor torque is 160.5 N·m, and the motor efficiency is 96.10%.

[0042] Example 3

[0043] In this embodiment, the magnetic steel is still designed as a three-layer structure, including two layers of neodymium iron boron material and a layer of magnetic conductive material in the middle, wherein the magnetic conductive material is a silicon steel sheet, the rotor disc thickness (i.e. the thickness of the magnetic steel) is 12 mm, and the thicknesses of the front and rear two layers of neodymium iron boron material are the same. The difference between Example 3 and Example 1 is that: the thickness of each layer of neodymium iron boron material is 4.2 mm, the thickness of the layer of magnetic conductive material is 3.6 mm, and the thickness of the layer of magnetic conductive material is 3 / 10 of the total thickness of the magnetic steel. At this time, the relative internal resistance of the magnetic steel is 0.7R0. Simulation test data shows that the motor line current effective value is 110 A, the motor torque is 163.7 N·m, and the motor efficiency is 96.22%.

[0044] Example 4

[0045] In this embodiment, the magnetic steel adopts two kinds of magnetic conductive materials, namely silicon steel sheet and low carbon steel sheet, and the magnetic steel is divided into four layers, which are neodymium iron boron layer (4.5 mm), silicon steel sheet layer (1.5 mm), low carbon steel layer (1.5 mm), and neodymium iron boron layer (4.5 mm) in turn. The thickness of the magnetic steel is 12 mm, the thickness of the layer of magnetic conductive material is 1 / 4 of the total thickness of the magnetic steel, and at this time, the relative internal resistance of the magnetic steel is 0.75R0. Simulation test data shows that the motor line current effective value is 110 A, the motor torque is 164.5 N·m, and the motor efficiency is 96.30%.

[0046] Example 5

[0047] In this embodiment, the magnetic steel adopts two kinds of magnetic conductive materials, namely silicon steel sheet and low carbon steel sheet, and the magnetic steel is divided into four layers, which are neodymium iron boron layer (4 mm), silicon steel sheet layer (2 mm), low carbon steel layer (2 mm), and neodymium iron boron layer (4 mm) in turn. The thickness of the magnetic steel is 12 mm, the thickness of the layer of magnetic conductive material is 1 / 3 of the total thickness of the magnetic steel, and at this time, the relative internal resistance of the magnetic steel is 0.667R0. Simulation test data shows that the motor line current effective value is 110 A, the motor torque is 160.6 N·m, and the motor efficiency is 96.06%.

[0048] Example 6

[0049] The magnetic steel in this embodiment adopts two kinds of magnetic conductive materials, which are silicon steel sheet and low carbon steel sheet respectively. The magnetic steel is divided into 4 layers, which are neodymium iron boron layer (4.2 mm), silicon steel sheet layer (1.8 mm), low carbon steel layer (1.8 mm), and neodymium iron boron layer (4.2 mm) in turn. The thickness of the magnetic steel is 12 mm, and the thickness of the magnetic conductive material layer is 3 / 10 of the total thickness of the magnetic steel. At this time, the relative internal resistance of the magnetic steel is 0.7R0. The simulation test data shows that the motor line current effective value is 110 A, the motor torque is 162.6 N·m, and the motor efficiency is 96.14%.

[0050] Example 7

[0051] The magnetic steel in this embodiment adopts two kinds of magnetic conductive materials, which are silicon steel sheet and low carbon steel sheet respectively. The magnetic steel is divided into 5 layers, which are neodymium iron boron layer (3 mm), silicon steel sheet layer (1.5 mm), neodymium iron boron layer (3 mm), low carbon steel layer (1.5 mm), and neodymium iron boron layer (3 mm) in turn. The thickness of the magnetic steel is 12 mm, and the thickness of the magnetic conductive material layer is 1 / 4 of the total thickness of the magnetic steel. At this time, the relative internal resistance of the magnetic steel is 0.75R0. The simulation test data shows that the motor line current effective value is 110 A, the motor torque is 164.8 N·m, and the motor efficiency is 96.30%.

[0052] Example 8

[0053] The magnetic steel in this embodiment adopts two kinds of magnetic conductive materials, which are silicon steel sheet and low carbon steel sheet respectively. The magnetic steel is divided into 5 layers, which are neodymium iron boron layer (2.67 mm), silicon steel sheet layer (2 mm), neodymium iron boron layer (2.67 mm), low carbon steel layer (2 mm), and neodymium iron boron layer (2.66 mm) in turn. The thickness of the magnetic steel is 12 mm, and the thickness of the magnetic conductive material layer is 1 / 3 of the total thickness of the magnetic steel. At this time, the relative internal resistance of the magnetic steel is 0.667R0. The simulation test data shows that the motor line current effective value is 110 A, the motor torque is 163.7 N·m, and the motor efficiency is 96.22%.

[0054] Example 9

[0055] The magnetic steel in this embodiment adopts two kinds of magnetic conductive materials, which are silicon steel sheet and low carbon steel sheet respectively. The magnetic steel is divided into 5 layers, which are neodymium iron boron layer (2.8 mm), silicon steel sheet layer (1.8 mm), neodymium iron boron layer (2.8 mm), low carbon steel layer (1.8 mm), and neodymium iron boron layer (2.8 mm) in turn. The thickness of the magnetic steel is 12 mm, and the thickness of the magnetic conductive material layer is 3 / 10 of the total thickness of the magnetic steel. At this time, the relative internal resistance of the magnetic steel is 0.7R0. The simulation test data shows that the motor line current effective value is 110 A, the motor torque is 163.7 N·m, and the motor efficiency is 96.22%.

[0056] Example 10

[0057] The magnetic steel in this embodiment is designed as a three-layer structure, including two layers of neodymium iron boron material and a layer of magnetic conductive material in the middle, wherein the magnetic conductive material is pure iron, the thickness of the rotor disc (i.e. the thickness of the magnetic steel) is 12 mm, the thickness of each layer of neodymium iron boron material is 4.5 mm, the thickness of the layer of magnetic conductive material is 3 mm, the thickness of the layer of magnetic conductive material is 1 / 4 of the total thickness of the magnetic steel, at this time, the relative internal resistance of the magnetic steel is 0.75R0. Simulation test data shows that the motor line current effective value is 110 A, the motor torque is 164.8 N·m, and the motor efficiency is 96.30%.

[0058] Embodiment 11

[0059] The magnetic steel in this embodiment is designed as a three-layer structure, including two layers of neodymium iron boron material and a layer of magnetic conductive material in the middle, wherein the magnetic conductive material is pure iron, the thickness of the rotor disc (i.e. the thickness of the magnetic steel) is 12 mm, the thickness of each layer of neodymium iron boron material is 4 mm, the thickness of the layer of magnetic conductive material is 4 mm, the thickness of the layer of magnetic conductive material is 1 / 3 of the total thickness of the magnetic steel, at this time, the relative internal resistance of the magnetic steel is 0.667R0. According to simulation test data, the motor line current effective value is 110 A, the motor torque is 162.6 N·m, and the motor efficiency is 96.14%.

[0060] Embodiment 12

[0061] The magnetic steel in this embodiment is designed as a three-layer structure, including two layers of neodymium iron boron material and a layer of magnetic conductive material in the middle, wherein the magnetic conductive material is pure iron, the thickness of the rotor disc (i.e. the thickness of the magnetic steel) is 12 mm, the thickness of each layer of neodymium iron boron material is 4.2 mm, the thickness of the layer of magnetic conductive material is 3.6 mm, the thickness of the layer of magnetic conductive material is 3 / 10 of the total thickness of the magnetic steel, at this time, the relative internal resistance of the magnetic steel is 0.7R0. Simulation test data shows that the motor line current effective value is 110 A, the motor torque is 162.6 N·m, and the motor efficiency is 96.14%.

[0062] Embodiment 13

[0063] In this embodiment, the magnetic steel is designed as a three-layer structure, including two layers of neodymium iron boron material and a layer of magnetic conductive material in the middle, wherein the magnetic conductive material is silicon steel sheet, the thickness of the rotor disc (i.e. the thickness of the magnetic steel) is 12 mm, the thickness of each layer of neodymium iron boron material is 5.25 mm, the thickness of the layer of magnetic conductive material is 1.5 mm, the thickness of the layer of magnetic conductive material is 1 / 8 of the total thickness of the magnetic steel, at this time, the relative internal resistance of the magnetic steel is 0.875R0. Simulation test data shows that the motor line current effective value is 110 A, the motor torque is 164.8 N·m, and the motor efficiency is 96.30%.

[0064] Embodiment 14

[0065] In the embodiment, the magnetic steel is designed as a three-layer structure, including two layers of neodymium iron boron material and a layer of magnetic conductive material in the middle, wherein the magnetic conductive material is silicon steel sheet, the rotor disc thickness (i.e. the thickness of the magnetic steel) is 12 mm, the thickness of each layer of neodymium iron boron material is 3 mm, the thickness of the layer of magnetic conductive material is 6 mm, the thickness of the layer of magnetic conductive material is 1 / 2 of the total thickness of the magnetic steel, at this time, the relative internal resistance of the magnetic steel is 0.5R0. The simulation test data shows that the motor line current effective value is 110 A, the motor torque is 110.6 N·m, and the motor efficiency is 86.30%.

[0066] Comparative Example

[0067] The magnetic steel in the comparative example is a conventional magnetic steel in the prior art, i.e. the magnetic steel is only made of pure neodymium iron boron material, the thickness of the magnetic steel is 12 mm, at this time, the relative internal resistance of the magnetic steel is recorded as R0, the simulation test data shows that the motor line current effective value is 110 A, the motor torque is 165.4 N·m, and the motor efficiency is 96.34%.

[0068] The motor diameter involved in each of the above embodiments and the comparative example is 260 mm. The comparison of the test results in each of the embodiments and the comparative example is shown in Table 1 below.

[0069] Table 1 Comparison of the magnetic steel internal resistance and the thickness of neodymium iron boron material in each of the embodiments and the comparative example

[0070]

[0071] Through the comparison of each of the above embodiments and the comparative example, the following conclusions can be obtained: the scheme of the present application can significantly reduce the internal resistance of the magnetic steel by replacing part of the neodymium iron boron material with magnetic conductive material, and can save the amount of neodymium iron boron material used in the magnetic steel. At present, the price of N38uh neodymium iron boron material is (290 yuan / kg), while the price of silicon steel material is (12 yuan / kg), the price of low carbon steel material is (6 yuan / kg), and the price of pure iron material is (7 yuan / kg). It can be seen that the scheme of the present application significantly reduces the manufacturing cost of the motor after replacing part of the neodymium iron boron material with magnetic conductive material.

[0072] The comparison of the test results of Example 1-12 and Example 13 is shown in Table 2 below.

[0073] Table 2 Comparison of the test results of Example 1-12 and Example 13

[0074]

[0075] By comparing the above-mentioned examples 1-12 with example 13, the following conclusions can be drawn: compared with example 13 which replaces 1.5 mm thick neodymium iron boron material, examples 1-12 replace at least 3 mm thick neodymium iron boron material, examples 1-12 further save 14.29%-23.81% of the amount of neodymium iron boron material compared with example 13, and the relative internal resistance of the magnetic steel is further reduced by 14.29%-23.77%, at the same time, the motor torque of examples 1-12 only decreases by 0.00%-2.61% compared with example 13, and the motor efficiency only decreases by 0.00%-0.25% compared with example 13. It can be seen that, under the premise of ensuring that the motor performance meets the requirements (meets the requirement that the motor efficiency is not less than 96%), replacing 3-4 mm thick neodymium iron boron material in examples 1-12 can further reduce the internal resistance of the magnetic steel of the motor and the manufacturing cost.

[0076] The comparison of the test results of examples 1-12, example 14 and the comparative example is shown in Table 3.

[0077] Table 3 Comparison of test results of examples 1-12, example 14 and the comparative example

[0078]

[0079] By comparing the above-mentioned examples 1-12, example 14 and the comparative example, the following conclusions can be drawn: compared with example 14 which replaces 6 mm thick neodymium iron boron material, examples 1-12 replace at most 4 mm thick neodymium iron boron material. Although example 14 can further reduce the internal resistance of the magnetic steel and reduce the amount of neodymium iron boron material, the motor torque (110.6 N·m) and the motor efficiency (86.30%) of example 14 are already significantly less than those of the comparative example, which does not meet the basic requirement that the motor efficiency is not less than 96%, i.e., example 14 cannot guarantee the motor performance requirements. The motor torque and the motor efficiency of examples 1-12 are basically the same as those of the comparative example, which meets the basic requirement that the motor efficiency is not less than 96%. It can be seen that, under the premise of not significantly affecting the motor performance, replacing at most 4 mm thick neodymium iron boron material in examples 1-12 can significantly reduce the internal resistance of the magnetic steel and the manufacturing cost of the motor.

[0080] Next, the influence of the change of the magnetic steel structure on the motor performance is illustrated by comparing examples 2, 5, 8 and 11, as shown in Table 4.

[0081] Table 4 Comparison of test results of examples 2, 5, 8 and 11

[0082]

[0083] By comparing the embodiment 2, 5, 8, 11, the following conclusions can be obtained: under the premise of saving 4mm thick Nd-Fe-B material, when the two different magnetic conductive materials such as silicon steel sheet and low carbon steel sheet in the embodiment 8 are alternately distributed with three layers of Nd-Fe-B, the magnetic steel internal resistance is consistent with the embodiment 2, 5 and 11, and the motor torque 163.7N·m and the motor efficiency 96.22% are obviously greater than the embodiment 2, 5 and 11, so it can be seen that under the premise of saving the same amount of Nd-Fe-B material, the five-layer structure of the magnetic steel in the embodiment 8 can further improve the motor performance compared with the embodiment 2, 5 and 11.

[0084] Through the above comparison and analysis, it can be known that the thickness of the magnetic conductive material (i.e. the magnetic conductive layer group 3) in the magnetic steel in the application preferably ranges from 1 / 4 to 1 / 3, and the magnetic steel is preferably designed as a five-layer structure, and two different magnetic conductive materials are used.

[0085] The application has the following beneficial effects:

[0086] 1) The scheme can reduce the magnetic field internal resistance of the motor magnetic steel, and keep a high motor working efficiency;

[0087] 2) The scheme can improve the utilization rate of the magnetic steel material, effectively reduce the amount of neodymium-iron-boron and other magnet materials, and thus reduce the manufacturing cost of the motor.

[0088] The application also provides a motor rotor comprising the magnetic steel described above. The derivation process of the beneficial effects of the motor rotor is generally similar to that of the magnetic steel, and thus will not be described herein.

[0089] Preferably, the motor rotor described above further comprises a magnetic steel holder 1 for fixing the magnetic steel.

[0090] The application also provides an axial magnetic field motor comprising the motor rotor described above. The derivation process of the beneficial effects of the axial magnetic field motor is generally similar to that of the magnetic steel, and thus will not be described herein.

[0091] The above description of disclosed embodiments enables those skilled in the art to carry out or use the application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A magnetic steel, characterized by, The magnetic steel comprises a group of magnetic conductive layers (3) and a magnetic layer (2) sandwiched between the group of magnetic conductive layers (3), the relative magnetic permeability of the group of magnetic conductive layers (3) is greater than that of the magnetic layer (2); The thickness of the group of magnetic conductive layers (3) is 1 / 4-1 / 3 of the total thickness of the magnetic steel; The group of magnetic conductive layers (3) comprises at least two layers of magnetic conductive layers arranged in a stack, and at least two adjacent layers of the magnetic conductive layers are provided with the magnetic layer (2).

2. The magnetic steel of claim 1, wherein The materials of the magnetic conductive layers are the same or different, or the materials of some layers of the magnetic conductive layers are the same. The materials of the magnetic layers (2) are the same or different, or the materials of some layers of the magnetic layers (2) are the same.

3. The magnetic steel of claim 1, wherein The thicknesses of the magnetic conductive layers are equal or different, or the thicknesses of some layers of the magnetic conductive layers are equal. The thicknesses of the magnetic layers (2) are equal or different, or the thicknesses of some layers of the magnetic layers (2) are equal.

4. The magnetic steel of claim 1 wherein, The material of the magnetic layer (2) is neodymium iron boron or ferrite, and the material of the magnetic conductive layer is silicon steel, low carbon steel or pure iron.

5. The magnetic steel of claim 1 wherein, The magnetic layer (2) and the group of magnetic conductive layers (3) are fixed by magnetic force, and / or the magnetic layer (2) and the group of magnetic conductive layers (3) are provided with fixing glue.

6. An electric machine rotor, characterized in that The magnetic steel comprises a group of magnetic conductive layers (3) and a magnetic layer (2) sandwiched between the group of magnetic conductive layers (3), the relative magnetic permeability of the group of magnetic conductive layers (3) is greater than that of the magnetic layer (2); 7. The motor rotor of claim 6, wherein The thickness of the group of magnetic conductive layers (3) is 1 / 4-1 / 3 of the total thickness of the magnetic steel; 8. An axial field electric machine characterized by The group of magnetic conductive layers (3) comprises at least two layers of magnetic conductive layers arranged in a stack, and at least two adjacent layers of the magnetic conductive layers are provided with the magnetic layer (2). The materials of the magnetic conductive layers are the same or different, or the materials of some layers of the magnetic conductive layers are the same. The materials of the magnetic layers (2) are the same or different, or the materials of some layers of the magnetic layers (2) are the same. The thicknesses of the magnetic conductive layers are equal or different, or the thicknesses of some layers of the magnetic conductive layers are equal. The thicknesses of the magnetic layers (2) are equal or different, or the thicknesses of some layers of the magnetic layers (2) are equal. The material of the magnetic layer (2) is neodymium iron boron or ferrite, and the material of the magnetic conductive layer is silicon steel, low carbon steel or pure iron. The magnetic layer (2) and the group of magnetic conductive layers (3) are fixed by magnetic force, and / or the magnetic layer (2) and the group of magnetic conductive layers (3) are provided with fixing glue. The magnetic steel comprises a group of magnetic conductive layers (3) and a magnetic layer (2) sandwiched between the group of magnetic conductive layers (3), the relative magnetic permeability of the group of magnetic conductive layers (3) is greater than that of the magnetic layer (2); The thickness of the group of magnetic conductive layers (3) is 1 / 4-1 / 3 of the total thickness of the magnetic steel; The group of magnetic conductive layers (3) comprises at least two layers of magnetic conductive layers arranged in a stack, and at least two adjacent layers of the magnetic conductive layers are

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