Patent ID: 12261492

The drawings include following reference signs:100. rotor sheet;10. rotor pole;101. first flux barrier layer;102. second flux barrier layer;103. third flux barrier layer;111. first slot;1110. slot section;112. second slot;121. first filling slot;122. second filling slot;123. third filling slot;120. beveled edge;20. shaft hole;2. central axis;3. direct axis;4. quadrature axis;200. end ring.

DETAILED DESCRIPTION

It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other given that there is no contradiction. The present disclosure will be described in detail hereinafter with reference to the drawings and in conjunction with the embodiments.

As shown inFIGS.1to3, an embodiment of the present disclosure provides a rotor structure, which includes a rotating shaft and a plurality of rotor sheets100sequentially stacked in the axial direction of the rotor structure. Each of the rotor sheets100is provided with a shaft hole20, through which the rotating shaft is to be inserted. The rotor sheet100is provided with a first slot111and first filling slots121at both ends of the first slot111. The first slot111includes slot sections1110at opposite sides of the shaft hole20. The first slot111, the first filling slots121, and the rotating shaft being inserted into the shaft hole20together form a first flux barrier layer, wherein the first slot111extends in a direction of a direct axis3of the rotor structure.

The rotor structure according to embodiments of the present disclosure is the rotor structure of the self-starting synchronous reluctance electric motor. The rotor structure includes the plurality of rotor sheets100stacked in sequence. The rotor sheet100is provided with the first slot111, the first filling slots121, and the shaft hole20. The first slot111extends in the direction of the direct axis3of the rotor structure. Two first filling slots121are located at opposite ends in the extending direction of the first slot111. The first slot111, the first filling slots121, and the rotating shaft being inserted into the shaft hole20together form the first flux barrier layer101. The shaft hole20divides the first flux barrier layer101into two sectional parts. The rotor structure according to embodiments of the present disclosure can increase the salient pole difference of the electric motor, improve the output torque of the electric motor, and improve the efficiency of the electric motor, which not only solves the problem of low electric motor efficiency in prior art, but also increases the utilization rate of space of the rotor core for manufacturing the rotor structure, which improves the starting capability of the electric motor.

In the self-starting synchronous reluctance electric motor, the direction of the magnetic field of the rotor is a direct axis3, also known as d-axis, and an quadrature axis4has an electrical angle of 90° relative to the direct axis3, and is also known as q-axis.

The flux barrier, i.e. the magnetic flux barrier, is a structure that blocks the magnetic lines of force from passing through. A magnetic channel is formed between two adjacent magnetic flux barriers in a same rotor pole10. The magnetic flux barrier is formed by an air-filled hollow slot or other magnetically non-conductive materials filled in the slot.

In particular, the rotor structure consists of two rotor poles10arranged in pair; and/or the rotating shaft is made of a magnetically non-conductive material; and/or an outer peripheral surface of the rotating shaft is cylindrical, or a part of the outer peripheral surface of the rotating shaft is composed of a part of a cylindrical surface.

The rotor structure according to an embodiment of the present disclosure includes two symmetrical rotor poles10. The rotating shaft being inserted in the shaft hole20of the rotor structure is made of a magnetically non-conductive material. At least part of the outer peripheral surface of the rotating shaft is cylindrical. The rotating shaft having the above shape can increase the width of the magnetic channel between the first flux barrier layer101and a second flux barrier layer102most adjacent to the shaft hole20.

As shown inFIG.2, a minimum distance L1 between the slot section1110and the shaft hole20is ranged as: σ≤L1≤5σ; and/or a minimum distance L2 between the slot section1110and its adjacent first filling slot121is ranged as: 0.8σ≤L2≤2σ, or L2=0, wherein σ is a width of an air gap between an inner diameter of a stator and an outer diameter of a rotor in the electric motor including the rotor structure.

The slot sections1110are located on both sides of the shaft hole20. In order to ensure the mechanical strength of connecting ribs at the connections between the slot sections1110and the shaft hole20while maximizing the use of the space of the rotor core, the minimum distance between the slot section1110and the rotating shaft is L1, and L1 shall satisfy σ≤L1≤5σ, wherein σ is a width of an air gap between an inner diameter of a stator and an outer diameter of a rotor in the electric motor including the rotor structure.

The minimum distance between the slot section1110and its adjacent first filling slot121is L2, which shall satisfy 0.8σ≤L2≤2σ or L2=0; that is, the slot section1110and its adjacent first filling slot121can be separated apart from each other or be connected with each other.

In some embodiments, the slot sections1110and the first filling slots121are filled with the same material; or the slot sections1110are air-filled slots.

When slot sections1110are the air-filled slots, the slot sections1110and their adjacent first filling slot121are disposed at intervals. By controlling the distance L2 between the slot section1110and its adjacent first filling slot121, the mechanical strength of the rotor core can be ensured, and the magnetic flux leakage between the slot section1110and the first filling slot121can be reduced.

The first flux barrier layer101composed of the slot sections1110, the first filling slots121and the magnetically non-conductive rotating shaft is a segmental flux barrier layer. When the slot sections1110and the first filling slots121are filled with the same filling material and the slot sections1110are connected with the first filling slots121, the first flux barrier layer101can increase the salient pole difference of the electric motor. As shown in the following equation (1), the salient pole difference is the difference between the d-axis inductance Ldand the q-axis inductance Lqof the electric motor. A greater salient pole difference can improve a capability of the electric motor to output the torque.

Te⁢m=12⁢p⁡(Ld-Lq)⁢is2⁢sin⁢2⁢β=p⁡(Ld-Lq)⁢id⁢iq(1)

In the equation (1), Temis an electromagnetic torque, p is the number of pole pairs of the electric motor, Ldis the d-axis inductance of the electric motor, Lqis the q-axis inductance of the electric motor, isis the stator current, idis the d-axis electric current of the electric motor, iqis the q-axis electric current of the electric motor, and β is current angle.

In addition, when the slot sections1110in the first flux barrier layer101are filled with the same filling material as that filled in the first filling slots121, the filling slot area in the d-axis can be increased and the d-axis electrical resistance can be reduced. As shown in the following equation (2),

Te_ave=32⁢P2⁢SSYNC⁢VS2ω⁢{1Rr⁢d⁢(Lm⁢dLd⁢s)2+1Rr⁢q⁢(Lm⁢qLq⁢s)2}(2)

In equation (2), Te_aveis the average electromagnetic torque, P is the number of pole pairs of the electric motor, SSYNCis the slip, ω is the electrical angular velocity of the electric motor, VSis the effective value of the voltage at the input, Rrdand Rrqare the d-axis electrical resistance and the q-axis electrical resistance of the rotor, respectively, Lmdand Lmqare the d-axis magnetizing inductance and the q-axis magnetizing inductance of the stator, respectively, Ldsand Lqsare the d-axis leakage inductance and the q-axis leakage inductance of the stator, respectively.

Since the d-axis leakage inductance Ldsand the q-axis leakage inductance Lqsof the stator are close, while the d-axis magnetizing inductance Lmdof the stator is far greater than the q-axis magnetizing inductance Lmqof the stator, so

(LmdLds)2≫(LmqLq⁢s)2.
Therefore, reducing the d-axis electrical resistance Rrdis a more effective way to raise the average electromagnetic torque Te_aveduring starting the electric motor. The slot sections1110in the first flux barrier layer101are filled with the same material as that filled in the first filling slots121, which increases the area of the filling slots in the d-axis and reduces the d-axis electrical resistance, thereby increasing the average electromagnetic torque Te_aveduring starting the electric motor and improving the starting capability of the electric motor.

As shown inFIG.2, the slot section1110is rectangular; and/or a minimum width h1 of the slot section1110is ranged as: 0.9h2≤h1≤1.1h2, wherein h2 is a width of the first filling slot121adjacent to the slot section1110.

In some embodiments, the shape of the slot section1110is rectangular or in other shapes.

Specifically, the minimum width of the slot section1110is h1, and the maximum width of the first filling slot121adjacent to the slot section1110is h2, and h1 and h2 shall satisfy 0.9h2≤h1≤1.1h2, so as to increase the area of the magnetically conducting channel extending in the direction of the direct axis3and adjacent to the slot sections1110, reduce the magnetic reluctance of the magnetic circuit of the rotor structure, and make the magnetic circuit of the rotor part more smooth.

As shown inFIG.2, opposite sides of the first flux barrier layer101each are provided with a group of second flux barrier layers102. Each group of second flux barrier layers102includes a plurality of second flux barrier layers102arranged in a direction of a quadrature axis4of the rotor structure. The second flux barrier layer102includes a second slot112and second filling slots122disposed at both ends of the second slot112.

The first flux barrier layer101is a segmental barrier layer, that is, the first slot111of the first flux barrier layer101is divided by the shaft hole20into two slot sections1110in the direction of the direct axis. The plurality of second flux barrier layers102are continuous barrier layers, that is, the second slot112of the second flux barrier layer102is continuous. The plurality second flux barrier layers102are located on both sides of the shaft hole20and distributed in the direction of the quadrature axis4.

In some embodiments, the minimum width h1 of the slot section1110is ranged as:

42⁢5⁢L⁢6≤12⁢h⁢1≤25⁢L⁢6,
wherein L6 is a minimum vertical distance in the direction of the quadrature axis4between the second slot112of the second flux barrier layer102closest to the direct axis3in each group of second flux barrier layers102and the direct axis3; and/or a minimum distance h4 in the direction of the quadrature axis4between the second slot112of the second flux barrier layer102closest to the direct axis3in each group of second flux barrier layers102and the first slot111is ranged as: L7≤h4≤1.65L7, wherein L7 is a minimum distance in the direction of the quadrature axis4between the shaft hole20and the second flux barrier layer102closest to the direct axis3.

The minimum width h1 of the slot section1110also satisfies

42⁢5⁢L⁢6≤12⁢h⁢1≤25⁢L⁢6,
wherein L6 is the minimum vertical distance in the direction of the quadrature axis4between the second flux barrier layer102closest to the shaft hole20and the direct axis3. This ensures the area of the magnetic channel extending in the direction of the direct axis3and adjacent to the slot sections1110, so as to ensure the smooth magnetic circuit of the rotor structure in the direct axis3direction, reduce the saturation of the magnetic flux density of the rotor structure and make the distribution of the rotor structure magnetic flux density more uniform.

The minimum distance in the direction of the quadrature axis4between the second slot112of the second flux barrier layer102closest to the shaft hole20in the second flux barrier layers102and the slot section1110of the first flux barrier layer101is h4, and the minimum distance in the direction of the quadrature axis4between the shaft hole20and the second flux barrier layer102closest to the shaft hole20is L7, h4 shall satisfy L7≤h4≤1.65L7, so that the smooth magnetic channel between the second flux barrier layer102closest to shaft hole20and the first flux barrier layer101can be ensured.

In some embodiments, in a same second flux barrier layer102, the second slot112and the second filling slots122are disposed at intervals and a width L3 of the interval is ranged as: 0.8σ≤L3≤2σ, wherein σ is a width of an air gap between an inner diameter of a stator and an outer diameter of a rotor in the electric motor formed by the rotor structure; and/or in a same second flux barrier layer102, a difference between a maximum width of the second filling slot122and a maximum width of the second slot112is smaller than or equal to 10% of the maximum width of the second slot112.

Each second slot112together with its corresponding second filling slots122constitutes each second flux barrier layer102of the rotor structure, wherein the second slot112in each second flux barrier layer102is separated from its corresponding second filling slots122by intervals, and the width L3 of the interval shall satisfy 0.8σ≤L3≤2σ, wherein σ is a width of an air gap between an inner diameter of a stator and an outer diameter of a rotor in the electric motor including the rotor structure. The second slot112and the second filling slots122are smoothly connected, and the difference between the maximum width of the second slot112and the maximum width of the second filling slot122in each second flux barrier layer102is smaller than or equal to 10% of the maximum width of the second slot112, wherein the maximum width of the second slot112refers to the maximum dimension of the second slot112in the direction of the quadrature axis4, and the maximum width of the second filling slot122refers to the maximum dimension of the second filling slot122in the direction of the quadrature axis4.

In this way, on the one hand, the mechanical strength of the rotor structure can be guaranteed, the magnetic flux leakage between the second slot112and the corresponding second filling slots122can be reduced, and on the other hand, controlling the width between the second slot112and the corresponding second filling slots122can reduce the magnetic reluctance of the magnetic circuit of the rotor structure, so that the magnetic channel of the rotor structure can be more smooth.

In some embodiments, in each group of second flux barrier layers102, a minimum distance L5 between two adjacent second flux barrier layers102is greater than 1.8h3, wherein h3 is a minimum width, in the direction of the quadrature axis4, of the second slot112of a smaller second flux barrier layer102in the two adjacent second flux barrier layers102.

The minimum distance between the two adjacent second flux barrier layers102in one rotor pole is L5, and the minimum width, in the direction of the quadrature axis4, of the smaller second flux barrier layer102in the two adjacent second flux barrier layers102is h3, wherein L5 shall be greater than 1.8h3.

In this way, on the one hand, the manufacturing difficulty of the rotor structure can be reduced, and on the other hand, the distribution uniformity of the magnetic flux density of the rotor structure can be guaranteed, and the saturation of the magnetic flux density of the rotor can be reduced.

In some embodiments, the width of each second slot112increases gradually from the quadrature axis4to both ends of the second slot112.

The width of the second slot112in each of the second flux barrier layers102gradually increases from the middle (i.e., the quadrature axis4) of the second slot112to both ends thereof, and the width of the second slot112refers to the dimension of the second slot112in the direction of the quadrature axis4.

As shown inFIGS.2and3, a third flux barrier layer103is disposed at a side of each group of second flux barrier layers102away from the first flux barrier layer101, and the third flux barrier layer103is composed of a third filling slot123.

Each rotor pole10includes the third flux barrier layer103. The third flux barrier layer103is a continuous barrier layer, located on the side of each group of second flux barrier layers102away from the first flux barrier layer101. The third flux barrier layer103includes the third filling slot123.

Specifically, an angle α of the third filling slot123occupied relative to a central axis2of the rotor structure is ranged as: 0.05τ≤α≤0.3τ, wherein τ=180°/p, and p is the number of pole pairs of the rotor structure.

The third filling slot123in the third flux barrier layer103is an independent filling slot. The third filling slot123occupies the angle α relative to the central axis2of the rotor structure, and α shall satisfies 0.05τ≤α≤0.3τ. In some embodiments, α satisfies 0.15τ≤α≤0.26τ, where τ is the polar distance angle, i.e., τ=180°/p, and p is the number of pole pairs of the rotor.

The third filling slot123can not only be used as a part of the third flux barrier layer103to improve the salient pole ratio of the electric motor, but also increase the area of the filling slots of the rotor structure of the electric motor, improving the starting capability of the electric motor. However, if the angle α of the third filling slot123is too large, the asynchronous torque of the electric motor will be reduced and the starting capability of the electric motor will become poor.

In some embodiments, in each group of second flux barrier layers102, a ratio of a sum of the widths of the second slots112of the second flux barrier layers102to the width between the shaft hole102and the outer peripheral surface of the rotor structure is in a range from 0.3 to 0.5.

As shown inFIG.2, one rotor pole10in the rotor structure according to the present disclosure includes four second flux barrier layers102and one third flux barrier layer103. In the direction of the direct axis3and away from the rotor structure, the widths of the second slots112of four second flux barrier layers102and the third filling slot123of one third flux barrier layer103are sequentially m1, m2, m3, m4, and m5. A sum of the minimum dimensions of the second flux barrier layers102and the third flux barrier layer103in the radial direction of the rotor sheet100is (m1+m2+m3+m4+m5). A width between the shaft hole20of the rotor sheet100and the outer peripheral surface of the rotor sheet100refers to the shortest distance from the shaft hole20to the outer peripheral surface of the rotor sheet100, wherein (m1+m2+m3+m4+m5)/m6=0.3 to 0.5.

Choosing a reasonable proportion for each flux barrier layer1not only can ensure a sufficient width of the flux barrier layer1, effectively block the quadrature axis magnetic flux, but also can ensure a reasonable magnetic channel, prevent the magnetic circuit oversaturation, increase the direct axis magnetic flux, and increase the salient pole ratio of the electric motor.

Specifically, both the first filling slots121and the second filling slots122extend to the outer peripheral surface of the rotor structure; and/or the first filling slots121and the second filling slots122are both filled with aluminum metal or aluminum alloy.

The first filling slots121and the second filling slots122in the filling slots of rotor structure are open slots, that is, the openings of the first filling slots121and the second filling slots122are located in the outer peripheral surface of the rotor sheet100. In contrast, the third filling slot123is a closed slot.

The filling slots includes the first filling slots121, the second filling slots122, and the third filling slots123filled with an electrically conductive but magnetically non-conductive material, such as aluminum metal or aluminum alloy. The filling material in the filling slots and the end rings200arranged at both ends of the rotor structure together form a short circuited connection and constitute a squirrel cage structure. The material of the end ring200is the same as the material filled in filling slots. This allows the structure to provide an asynchronous torque during the starting phase of the electric motor to implement the self-starting of the self-starting synchronous reluctance electric motor.

In some embodiments, openings of the first filling slots121and the second filling slots122are located at the ends of the slots and at sides adjacent to the direct axis3, or the openings of the first filling slots121and second filling slots122are located in the middles of the ends of the slots.

As shown inFIGS.2and3, the widths of the openings of the first filling slots121and the second filling slots122are smaller than the widths of the first filling slots121or the second filling slots122. The openings of the first filling slots121and the second filling slots122are located at the ends of the corresponding first filling slots121and second filling slots122adjacent to the outer peripheral surface of the rotor sheet100and at the sides of the corresponding first filling slots121and second filling slots122adjacent to the direct axis3. Alternatively, the openings of the first filling slots121and the second filling slots122are located at the ends of the corresponding first filling slots121and second filling slots122adjacent to the outer peripheral surface of the rotor sheet100and located in the middles of the ends.

In some embodiments, the ends of the first filling slots121and the second filling slots122each include a beveled edge120at the side away from the direct axis3adjacent thereto, or each include beveled edges120at both sides of the end of the first filling slot121or the second filling slot122. The beveled edges120are connected to edges of the openings of the corresponding first filling slots121and second filling slots122.

Specifically, the ends of the first filling slots121and the second filling slots122are each provided with the beveled edge120on the side thereof away from the direct axis3or on both sides of the middles thereof, and the beveled edge(s)120is connected with the openings of the corresponding first filling slots121and the second filling slots122, forming a half-opened slot structure of the first filling slots121and the second filling slots122. By setting the beveled edges120, the magnetic channels between the first filling slots121and the second filling slots122adjacent to the outer peripheral surface of the rotor structure become wider, and the direct axis magnetic flux may enter the stator smoothly along the beveled edges120, so as to reduce the influence of the openings of the first filling slots121and second filling slots122on the direct axis magnetic flux and to ensure the direct axis inductance. Meanwhile, the beveled edges120can also improve the distribution of the magnetic flux, slow down the change of the magnetic flux, reduce the torque ripple caused by the interactions of the stator teeth, and reduce the vibration noise of the electric motor. In addition, the openings can effectively block the quadrature axis magnetic flux, reduce the quadrature axis inductance, increase the inductance difference between the direct axis and the quadrature axis, and improve the electric motor output torque and efficiency.

In some embodiments, an angle between the beveled edge120and a slot wall of the first filling slot121or the second filling slot122connected to the beveled edge120is β, and 125°≤β≤165°. The beveled edge120can reduce the influence of the corresponding opening of the first filling slot121or the second filling slot122on the direct axis inductance, so that the direct axis magnetic lines of force can enter the stator smoothly and produce torque. Meanwhile, the beveled edge120can reduce a sudden change of the inductance of the electric motor, and lower the reluctance torque ripple.

As shown inFIG.2, a width of the opening of the first filling slot121and/or that of the second filling slot122is L4, wherein 0.5σ≤L4≤4σ, σ is a width of an air gap between an inner diameter of a stator and an outer diameter of a rotor in the electric motor including the rotor structure; and/or the width L4 of the opening of the first filling slot121and/or that of the second filling slot122is less than a maximum thickness w of the first filling slot121or that of the second filling slot122.

The width of the opening of the first filling slot121and/or that of the second filling slot122is L4, and L4 satisfies 0.5σ≤L4≤4σ, σ is a width of an air gap between an inner diameter of a stator and an outer diameter of a rotor in the electric motor including the rotor structure, and in some embodiments, the width L4 of the opening of the first filling slot121and/or that of the second filling slot122satisfies 1.5σ≤L4≤3σ.

In some embodiments, the width L4 of the opening of the first filling slot121and/or that of the second filling slot122is ranged as: 0.1w≤L4≤0.7w, wherein w is the maximum thickness of the first filling slot121or that of the second filling slot122. In this way, through an appropriate width of the opening of the first filling slot121and/or the second filling slot122can be obtained, which is beneficial to achieve an optimum inductance difference of the electric motor in order to improve the electric motor efficiency.

Specifically, in a same second flux barrier layer102, an area of the second filling slots122in the surface of the rotor sheet100is greater than 40% of a sum of an area of the second slot112and an area of the second filling slots122of the second flux barrier layer102in the surface of the rotor sheet100.

In the same second flux barrier layer102, the area of the second filling slots122is greater than 40% of the area of the corresponding second flux barrier layer102. In some embodiments, the area of the second filling slots122is in a range from 40% to 60% of the area of the corresponding second flux barrier layer102, so as to ensure that the electric motor has a sufficient self-starting capability.

Specifically, in a same first flux barrier layer101, an area of the first filling slots121in the surface of the rotor sheet100is greater than 30% of a sum of an area of the first slot111and an area of the first filling slots121of the first flux barrier layer101in the surface of the rotor sheet100.

In the same first flux barrier layer101, the area of the first filling slots121is greater than 30% of the area of the corresponding first flux barrier layer101. In some embodiments, the area of the first filling slots121is in a range from 30% to 100% of the area of the corresponding first flux barrier layer101, so as to improve the loaded starting capability of the electric motor.

According to a second aspect of the present disclosure, an electric motor is provided, including a stator and a rotor. The rotor is the above-described rotor structure.

According to a third aspect of the present disclosure, a rotor manufacturing method is provided for manufacturing the above-described rotor structure. The rotor manufacturing method includes: preparing a rotor core having an outer peripheral surface larger than the outer peripheral surface of the rotor structure, so that temporary bars are formed between the openings of the filling slots of the rotor structure and the outer peripheral surface of the rotor core; filling the filling slots with a material to be filled and installing the end rings200; and removing the temporary bars to form the rotor structure

The rotor manufacturing method disclosed herein is specifically as follows:

First, a rotor core is manufactured. The outer peripheral surface of the rotor core is slightly larger in diameter than that of the rotor sheet100described above. At this time, the openings of the filling slots are sealed with the temporary bars provided at the corresponding openings of the filling slots. The temporary bars space the filling slots from the outer peripheral surface of rotor core.

Then, the filling slots are filled with the material, and the filled material are welded with the end rings200on both sides in the axial direction of the rotor core to form the squirrel cage structure.

Finally, by a machining method such as turning, the temporary bars are removed to form the openings of the filling slots to form the half-opened structure, thereby producing the rotor structure as shown inFIG.1.

As shown inFIG.4, from the comparison graph between the time-dependent output torque of the electric motor including the rotor structure of the present disclosure and the time-dependent output torque of the electric motor including the rotor structure according to related art, it can be seen that the output torque of the electric motor including the rotor structure of the present disclosure has increased significantly compared with the output torque of the electric motor including the rotor structure of the prior art. The rotor structure of the present disclosure can increase the output torque of the electric motor.

In specific implementations of the present disclosure, the slot section1110and the adjacent first filling slot121are spaced from or connected to each other; the third flux barrier layer103can be an independent filling slot or a combination of a filling slot and a hollow slot; the slot section1110can be rectangular or have other regular or irregular shape; the shape of the shaft hole20can be completely circular or partially circular; the first filling slots121and the second filling slots122can be the open slots or the closed slots; when the first filling slots121and the second filling slots122are the open slots, the openings can be located at one side of the ends of the corresponding filling slots adjacent to the direct axis3or in the middles of the ends of the corresponding filling slots, or both.

From the above description, it can be seen that the above embodiments of the present disclosure realize the following technical effects.(1) By setting the segmental first flux barrier layer101in the direction of the direct axis3of the rotor structure, the salient pole difference of the electric motor can be increased and the torque output capability of the electric motor can be improved.(2) By filling the slot sections1110with the same filling material as that in the first filling slots121, the area of the filling slots in the direct axis can be increased, the direct axis electrical resistance can be reduced, the average torque of the electric motor in the starting process can be increased, the starting capability of electric motor can be improved, and the utilization rate of the rotor core space can be increased.(3) The self-starting of electric motor is realized by an asynchronous torque provided by rotor conducting bars (that is, the bar structure formed by the filling material in filling slots), which solves the problem that the synchronous reluctance electric motor needs a variable-frequency drive, reduces the loss of electric motor, improves the efficiency of the electric motor, and solves the problem of low efficiency of the electric motor in prior art.

Those described above are just embodiments of the present disclosure, rather than limitations thereto. For persons skilled in the art, various modifications and changes can be made to the present disclosure. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present disclosure shall fall within the protection scope of the present disclosure.