Embedded permanent magnet synchronous motor

Abstract

The invention discloses an embedded permanent magnet synchronous motor, which comprises a rotating shaft, a rotor core arranged on the rotating shaft and a stator core matched with the rotor core, a plurality of stator slots are uniformly distributed on the inner edge of the stator core, stator windings are arranged in the plurality of stator slots, an even number of permanent magnet slots are uniformly distributed on the outer edge of the rotor core, and the permanent magnet slots are arranged in the stator windings. The permanent magnet grooves are located on the rotor iron core and are symmetrically distributed relative to each rotor straight axis d, and permanent magnets are arranged in the permanent magnet grooves; a plurality of rotor slots are uniformly distributed on the outer edge of the rotor core, the rotor slots are positioned between adjacent permanent magnet slots, and mouse cage strips are arranged in the rotor slots; and a plurality of V-shaped air slots are uniformly arranged on the rotor core and are positioned on a quadrature-axis magnetic circuit of the rotor core. The motor has the characteristics of compact structure, convenience in disassembly and assembly, low saturation degree of a straight-axis magnetic circuit and the like, and the running stability of the motor is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of motor technology, in particular to an embedded permanent magnet synchronous motor. BACKGROUND

[0002] The operation principle of permanent magnet synchronous motor is similar to that of electrically excited synchronous motor, but it uses permanent magnet to replace the excitation winding to generate excitation magnetic flux, which greatly simplifies the structure of the motor. According to the spatial position relationship between the permanent magnet and the rotor core of the motor, the rotor structure of rare earth permanent magnet synchronous motor is classified into three types, i.e. convex mounting type, embedded type and built-in type, as shown in Figure 1

[0003] The convex mounting type and embedded type are collectively referred to as external rotor structure. The diameter of the rotor of the motor of this structure can be made very small, so that the rotational inertia of the rotor is small, and the permanent magnet is fixed on the outside of the rotor by a high-strength non-magnetic ring or is directly bonded to the outside of the rotor, which can obtain a lower inductance, which is beneficial to improve the dynamic characteristics of the motor. The disadvantage is that the conductor is located inside the rotor, and the limited air gap can be cut, so the asynchronous torque generated is small, and the starting performance is not high.

[0004] In the built-in rotor structure, the permanent magnet is embedded in the rotor core between the squirrel cage conductor and the shaft hole of the core. For this rotor structure, the shaft reluctance is greater than the shaft reluctance, and the shaft magnetic circuit of the rotor is asymmetric, which causes the reluctance torque to be beneficial to enhance the overload capacity, and the rotor slot directly faces the air gap, which helps to improve the asynchronous torque of the motor and the starting performance. The disadvantage of the built-in rotor structure is that the magnetic leakage is large, and necessary magnetic isolation measures need to be taken, and the mechanical strength of the rotor is relatively weak.

[0005] Unlike traditional electrically excited motors, due to the high magnetic permeability of rare earth permanent magnets and air, for permanent magnet synchronous motors with embedded and built-in rotor structures, the direct-axis magnetic reluctance is greater than the quadrature-axis magnetic reluctance, so the direct-axis synchronous reactance is smaller than the quadrature-axis synchronous reactance, and the reluctance torque component is negative when the power angle is less than 90°, and the maximum electromagnetic torque corresponds to a power angle greater than 90°. When the motor is running under load with a power angle greater than 90°, the direct-axis armature reaction magnetic field and the rotor permanent magnet magnetic field are in opposite directions, which plays a demagnetizing role, thereby causing the permanent magnet to have a large demagnetization risk when the motor is running under load. In addition, the quadrature-axis magnetic circuit is oversaturated when running under load, the iron loss is large, and the efficiency of the motor is not high.

[0006] ​In the existing permanent magnet synchronous motor, the shell and the stator core are usually in interference fit, and the stator core is sleeved into the shell by mechanical pressing. If the interference is too small, the stator core may rotate relative to the shell, and if the interference is too large, the shell may be deformed or even cracked. Moreover, the interference fit of the shell and the stator core also causes difficulty in disassembly, and even cannot be disassembled. SUMMARY

[0007] The technical problem to be solved by the present application is to provide an embedded permanent magnet synchronous motor with compact structure, convenient disassembly and reduction of iron loss.

[0008] In order to solve the above technical problems, the technical scheme adopted by the present application is: An embedded permanent magnet synchronous motor, comprising a rotating shaft, a rotor core arranged on the rotating shaft, and a stator core matched with the rotor core, wherein the inner edge of the stator core is uniformly provided with a plurality of stator slot, each of the plurality of stator slot is provided with a stator winding, the outer edge of the rotor core is uniformly provided with an even number of permanent magnet slots, the permanent magnet slots are symmetrically distributed on the rotor core relative to each rotor straight axis d, and a permanent magnet is arranged in each permanent magnet slot; a plurality of rotor slots are also uniformly arranged on the outer edge of the rotor core, the rotor slots are located between adjacent permanent magnet slots, and a squirrel cage bar is arranged in each rotor slot; a plurality of V-shaped air slots are uniformly arranged on the rotor core, and the V-shaped air slots are located on the quadrature axis magnetic circuit of the rotor core.

[0009] As a further improvement of the present application, a shell is further included, a plurality of wedge grooves are arranged on the inner edge of the shell and the outer edge of the stator core, the radial direction of the stator core and the shell are fixed by inserting a wedge key into the wedge grooves, and the remaining wedge grooves are used for axial ventilation.

[0010] As a further improvement of the present application, a plurality of ventilation holes are uniformly arranged on the stator core.

[0011] As a further improvement of the present application, the squirrel cage bar comprises an inner conductor and an outer conductor, and the outer conductor is symmetrically arranged on both sides of the inner conductor.

[0012] As a further improvement of the present application, the inner conductor is made of conductive material, and the outer conductor is made of magnetically conductive and conductive material.

[0013] As a further improvement of the present application, end rings are arranged at both ends of the squirrel cage bar, and a plurality of squirrel cage bars on the rotor core are short-circuited by the end rings.

[0014] As a further improvement of the present application, a front end cover and a rear end cover are arranged at both ends of the shell respectively, a fan is arranged in the rear end cover, and the fan is connected with the end portion of the rotating shaft; when the rotating shaft rotates, the fan rotates and inhales cold air from the outside of the motor to cool the inside of the motor.

[0015] As a further improvement of the present application, the V-shaped air slots are symmetrically arranged in pairs.

[0016] As a further improvement of the present application, a plurality of rotor slots are arranged between the two adjacent permanent magnet slots.

[0017] As a further improvement of the present application, the rotor slots are in V-shaped structure.

[0018] Compared with the prior art, the present application has the following advantages: The embedded permanent magnet synchronous motor of the present application has the following advantages: the permanent magnets are embedded on the outer edge of the rotor core, the shape of the rotor can be optimized as eccentric structure, which is beneficial to reduce the air gap harmonics and the cogging torque; at the same time, a plurality of rotor slots are evenly arranged on the outer edge of the rotor core, and the rotor slots are located between the adjacent permanent magnet slots, and the squirrel cage bars are arranged in the rotor slots, which increases the self-starting ability and the steady-state synchronous operation ability of the permanent magnet synchronous motor; further, a plurality of V-shaped air slots are evenly arranged on the rotor core, and the V-shaped air slots are located on the quadrature axis magnetic circuit of the rotor core, which increases the magnetic resistance of the quadrature axis magnetic circuit, so that the magnetic circuit is not easy to be saturated, the iron loss is reduced, and the influence of the quadrature axis armature reaction on the direct axis air gap permanent magnet magnetic field during the operation of the motor is also reduced. In addition, the existence of the air slots can also improve the heat dissipation performance of the rotor, reduce the temperature of the rotor, and protect the permanent magnets. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Fig. 1 is a schematic diagram of different rotor structures of the permanent magnet synchronous motor; Figure 2 Fig. 2 is a schematic diagram of the structure principle of the embedded permanent magnet synchronous motor in the specific embodiment of the present application; Figure 3 Fig. 3 is a schematic diagram of the structure principle of the embedded permanent magnet synchronous motor from another perspective in the specific embodiment of the present application; Figure 4 Fig. 4 is a schematic diagram of the structure principle of the squirrel cage bars in the specific embodiment of the present application; Fig. 1 is a schematic diagram of different rotor structures of the permanent magnet synchronous motor; DETAILED DESCRIPTION

[0020] The present application will be further described below in combination with the drawings and specific preferred embodiments, but the protection scope of the present application is not limited thereto.

[0021] In the description of the present application, it should be understood that the terms "side", "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0022] In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated, so that the features with "first" and "second" can explicitly or implicitly include one or more of the features, and in the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly and specifically limited.

[0023] Embodiments As shown in Figure 2 and Figure 3 The embedded permanent magnet synchronous motor of the present application comprises a rotating shaft 10, a rotor core 9 arranged on the rotating shaft 10, and a stator core 13 matched with the rotor core 9. The inner edge of the stator core 13 is uniformly distributed with a plurality of stator slot 16, and the plurality of stator slot 16 is arranged with a stator winding 7. The outer edge of the rotor core 9 is uniformly distributed with an even number of permanent magnet slots 12, which are symmetrically distributed on the rotor core 9 relative to each rotor direct axis d, and the permanent magnet slots 12 are arranged with permanent magnets 8. The outer edge of the rotor core 9 is also uniformly distributed with a plurality of rotor slots 11, which are located between adjacent permanent magnet slots 12, and the rotor slots 11 are arranged with squirrel cage bars 5. The squirrel cage structure is beneficial to increase the low-speed starting ability of the motor. When the rotor speed is inconsistent with the speed of the stator rotating magnetic field during normal operation, the squirrel cage bars 5 generate torque to shorten the time for the rotor to reach the stator rotating magnetic field. The rotor core 9 is uniformly provided with a plurality of V-shaped air slots 6, which are located on the quadrature axis magnetic circuit of the rotor core 9.

[0024] As shown in Figure 2 The three V-shaped rotor slots 11 are arranged between the two adjacent permanent magnet slots 12, and the squirrel cage bars 5 are arranged in the rotor slots 11, so that the motor can generate greater starting torque when starting. The squirrel cage bars 5 disperse the current and avoid excessive local current density, thereby reducing the copper loss of the rotor. The rotor slots 11 can also adopt rectangular, trapezoidal and similar structures to increase the quadrature axis reluctance.

[0025] In this embodiment, by distributing even number of permanent magnet slots 12 on the outer edge of the rotor core 13, the permanent magnet 8 is installed in the form of embedding on the outer edge of the rotor core 13, the shape of the rotor can be optimized as eccentric structure, which is conducive to reducing the air gap harmonic and the cogging torque. At the same time, a plurality of rotor slots 11 are also distributed on the outer edge of the rotor core 13, and the rotor slots 11 are located between adjacent permanent magnet slots 12, and the squirrel cage bars 5 are arranged in the rotor slots 11, which increases the self-starting ability and steady-state synchronous running ability of the permanent magnet synchronous motor. Further, a plurality of V-shaped air slots 6 are uniformly arranged on the rotor core 13, and the V-shaped air slots 6 are located on the quadrature axis magnetic circuit of the rotor core 13, which increases the magnetic resistance of the quadrature axis magnetic circuit, so that the magnetic circuit is not easy to saturate, reduces the iron loss, and at the same time can reduce the influence of the cross-axis armature reaction on the direct-axis air gap permanent magnet magnetic field during the operation of the motor. In addition, the existence of the air slot can also improve the heat dissipation performance of the rotor, reduce the temperature of the rotor, and protect the permanent magnet.

[0026] As shown in Figure 2 , it also includes a casing 4, and a plurality of wedge grooves 2 are arranged on the inner edge of the casing 4 and the outer edge of the stator core 13. The radial direction of the stator core 13 and the casing 4 are fixed by inserting the wedge key 1 into the wedge groove 2, and the remaining wedge grooves 2 are used for axial ventilation. The casing 4 and the stator core 13 are matched by wedge key, which is simple to disassemble. The casing 4 and the stator core 13 can be separated by removing the wedge key, without damaging the structure of the casing 4 and the stator core 13, reducing the assembly process difficulty, and also reducing the deformation amount of the stator core 13 and the casing 4. Further, the wedge groove 2 can adopt circular, rectangular or trapezoidal shape.

[0027] As shown in Figure 2 , a plurality of ventilation holes 3 are uniformly arranged on the stator core 13. The ventilation holes 3 and the wedge grooves 2 provide an effective dissipation channel for the heat inside the motor, so that the heat generated during the operation of the motor can be quickly taken away, reducing the copper loss and iron loss caused by temperature rise, and improving the efficiency of the motor.

[0028] As shown in Figure 4 , the squirrel cage bar 5 includes an inner guide bar 51 and an outer guide bar 52, and the outer guide bar 52 is symmetrically arranged on both sides of the inner guide bar 51. The inner guide bar 51 and the outer guide bar 52 are respectively located at different positions of the rotor slot 11, and the paths of cutting magnetic lines are different, so the distribution of induced electromotive force and current is also different, so that the motor can generate greater electromagnetic torque at the starting moment, so as to more easily overcome the inertia of the load and realize rapid starting.

[0029] In this embodiment, the inner conductor bar 51 is made of conductive material, and the outer conductor bar 52 is made of magnetically conductive and conductive material. Specifically, the squirrel cage bar 5 is made of alloy material, the inner conductor bar 51 can be made of red copper, and the outer conductor bar 52 can be made of copper-iron alloy or aluminum-iron alloy. Due to the different current distributions of the inner conductor bar 51 and the outer conductor bar 52, the double-layer squirrel cage structure can optimize the starting characteristic curve of the motor. During the starting process, the current distribution in the inner and outer conductor bars will gradually change as the speed increases, making the starting current more stable, reducing the current impact, and reducing the impact on the power grid.

[0030] In this embodiment, both ends of the squirrel cage bar 5 are provided with end rings (not shown in the figure), and a plurality of squirrel cage bars 5 on the rotor core 9 are short-circuited through the end rings. When the squirrel cage bars 5 are short-circuited through the end rings, a complete short-circuit loop is formed. When the motor starts, the stator winding 7 generates a rotating magnetic field, and the squirrel cage bar 5 cuts the magnetic lines of force, which will induce an electromotive force in the squirrel cage bar 5. Due to the presence of the end ring, the induced electromotive force will generate an induced current in the closed loop formed by the squirrel cage bar 5 and the end ring, and the magnetic field generated by the induced current will interact with the stator magnetic field, thereby generating an electromagnetic torque. Moreover, the induced current is distributed in the short-circuit loop according to a certain rule, avoiding the violent fluctuation of the current, so that the starting current of the motor is relatively stable. In addition, the end ring connects the squirrel cage bars 5 together to form a whole structure, which enhances the mechanical strength of the rotor and can better withstand the centrifugal force. When the motor rotates at high speed, the rotor is subjected to a large centrifugal force, and the squirrel cage bar structure short-circuited by the end ring can effectively prevent the rotor conductor bar from loosening or breaking, ensuring the long-term stable operation of the motor.

[0031] As shown in Figure 2 , the V-shaped air slots 6 are symmetrically arranged in pairs, which can effectively take away the heat generated inside the motor, and through effective heat dissipation, the motor can operate at a higher power density.

[0032] As shown in Figure 3 , the two ends of the casing 4 are respectively provided with a front end cover 15 and a rear end cover 17, and the rear end cover 17 is provided with a fan 14, and the fan 14 is connected with the end of the rotating shaft 10. When the rotating shaft 10 rotates, the fan 14 rotates and inhales cold air from the outside of the motor, and flows through the heat dissipation channels formed by the wedge grooves 2, the ventilation holes 3 and the V-shaped air slots 6, so as to cool the heat transferred by the rotor core 9 and the stator core 13, so as to realize the internal cooling of the motor. In other embodiments, a wind tube connected to an external air source can be used instead of the fan 14.

[0033] The above merely describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-described embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. An embedded permanent magnet synchronous motor, comprising a rotating shaft (10), a rotor core (9) disposed on the rotating shaft (10), and a stator core (13) cooperating with the rotor core (9), wherein a plurality of stator slots (16) are evenly distributed on the inner edge of the stator core (13), and stator windings (7) are disposed in each of the plurality of stator slots (16), characterized in that, An even number of permanent magnet slots (12) are evenly distributed on the outer edge of the rotor core (9). The permanent magnet slots (12) are symmetrically distributed on the rotor core (9) relative to each rotor axis (d). Permanent magnets (8) are provided in the permanent magnet slots (12). A number of rotor slots (11) are also evenly distributed on the outer edge of the rotor core (9). The rotor slots (11) are located between adjacent permanent magnet slots (12). Squirrel cage bars (5) are provided in the rotor slots (11). A number of V-shaped air slots (6) are evenly distributed on the rotor core (9). The V-shaped air slots (6) are located on the cross-axis magnetic path of the rotor core (9).

2. The embedded permanent magnet synchronous motor according to claim 1, characterized in that, It also includes a housing (4), the inner edge of the housing (4) and the outer edge of the stator core (13) are provided with multiple wedge grooves (2), the radial direction of the stator core (13) and the housing (4) are fixed by inserting wedge keys (1) into the wedge grooves (2), and the remaining wedge grooves (2) are used for axial ventilation.

3. The embedded permanent magnet synchronous motor according to claim 2, characterized in that, The stator core (13) is provided with a plurality of ventilation holes (3) evenly distributed.

4. The embedded permanent magnet synchronous motor according to claim 2, characterized in that, The cage bar (5) includes an inner guide bar (51) and an outer guide bar (52), with the outer guide bar (52) symmetrically arranged on both sides of the inner guide bar (51).

5. The embedded permanent magnet synchronous motor according to claim 4, characterized in that, The inner conductor (51) is made of conductive material, and the outer conductor (52) is made of magnetic and conductive material.

6. The embedded permanent magnet synchronous motor according to claim 4, characterized in that, Both ends of the rat cage bar (5) are provided with end rings, and multiple rat cage bars (5) on the rotor core (9) are short-connected through the end rings.

7. The embedded permanent magnet synchronous motor according to any one of claims 2 to 6, characterized in that, The housing (4) has a front cover (15) and a rear cover (17) at its two ends respectively. A fan (14) is provided inside the rear cover (17). The fan (14) is connected to the end of the shaft (10). When the shaft (10) rotates, the fan (14) rotates and draws in cold air from outside the motor to achieve internal cooling of the motor.

8. The embedded permanent magnet synchronous motor according to any one of claims 1 to 6, characterized in that, The V-shaped air troughs (6) are arranged symmetrically in pairs.

9. The embedded permanent magnet synchronous motor according to any one of claims 1 to 6, characterized in that, Multiple rotor slots (11) are provided between two adjacent permanent magnet slots (12).

10. The embedded permanent magnet synchronous motor according to any one of claims 1 to 6, characterized in that, The rotor slot (11) has a V-shaped structure.

Images