Rotor core, rotor, and permanent magnet synchronous motor

Abstract

The application relates to a rotor core, a rotor and a permanent magnet synchronous motor, wherein the rotor core is provided with an axle hole and a plurality of first magnetic steel grooves which are uniformly distributed along the circumference of the axle hole; the first magnetic steel grooves are suitable for installing permanent magnets, and a magnetic isolation groove is formed at one end of the adjacent permanent magnets with different magnetic poles; an auxiliary hole is arranged between the adjacent magnetic isolation grooves. The minimum distance h1 between the magnetic isolation groove and the circumference of the rotor core is less than or equal to the minimum distance h2 between the auxiliary hole and the adjacent magnetic isolation groove. The volume and position of the auxiliary hole relative to the magnetic isolation groove satisfy the first condition to reduce the magnetic steel eddy current loss. The rotor core takes into account the inhibition effect of the eddy current loss of the permanent magnet of the motor, the manufacturing difficulty of the motor and the motor performance.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment technology, and in particular to a rotor core, a rotor, and a permanent magnet synchronous motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) have advantages such as high energy density, high efficiency, simple structure, reliable operation, and small size. However, with the development of PMSMs towards higher speeds and higher power, the proportion of eddy current losses in the permanent magnets is increasing, leading to higher internal temperature rise, reduced efficiency, and affecting the normal operation of the motor.

[0003] Besides the pursuit of higher speeds and greater power, the stator of a permanent magnet synchronous motor, with its concentrated winding layout, is also prone to eddy current losses in the permanent magnets. Since most concentrated winding motors have a fractional slot structure and the windings are concentrated, the harmonic content in the air gap is relatively high. These harmonics are easily conducted through the rotor core, and subsequently form surface eddy current losses in the permanent magnets.

[0004] Compared to surface-mounted permanent magnet synchronous motors, the permanent magnets in built-in permanent magnet synchronous motors are located inside the rotor core, resulting in poorer heat dissipation. Significant eddy current losses and excessive temperature rise will inevitably have a severe impact on the performance of the permanent magnets and the efficiency of the motor. Therefore, suppressing eddy current losses in the permanent magnets of built-in permanent magnet synchronous motors is of great practical significance and value.

[0005] Generally speaking, there are various methods to reduce eddy current losses in the permanent magnets of built-in permanent magnet synchronous motors. Although these methods can suppress eddy current losses to a certain extent, they also have a significant impact on motor performance or greatly increase the difficulty of motor manufacturing. Summary of the Invention

[0006] Based on this, a rotor core is provided that aims to balance the suppression of eddy current losses in the permanent magnets of the motor, the difficulty of motor manufacturing, and motor performance.

[0007] A rotor core has a shaft hole and several first magnetic steel slots evenly distributed around the shaft hole. The first magnetic steel slots are suitable for mounting permanent magnets, and magnetic isolation slots are formed at the ends of adjacent permanent magnets with different magnetic poles. An auxiliary hole is opened between adjacent magnetic isolation slots. The minimum distance h1 between the magnetic isolation slot and the periphery of the rotor core is less than or equal to the minimum distance h2 between the auxiliary hole and the adjacent magnetic isolation slot. The volume and position of the auxiliary hole relative to the magnetic isolation slot satisfy a first condition to reduce eddy current losses of the magnets.

[0008] In one embodiment, the magnetic shielding groove has a first side and a second side, and the auxiliary hole has a side edge close to the magnetic shielding groove in the circumferential direction; the first side is disposed corresponding to the periphery, and the minimum distance between it and the periphery is the minimum distance h1; the second side is disposed corresponding to the side edge of the auxiliary hole, its radial length is c, and the minimum distance between it and the side edge of the auxiliary hole is the minimum distance h2; wherein, the maximum radial length of the auxiliary hole is a; the minimum radial distance between the auxiliary hole and the periphery is b; the first condition includes 2c≥a≥0.5c, and h1<b≤c.

[0009] In one embodiment, the minimum distance h2 between one side edge of the auxiliary hole and the adjacent second side is greater than or less than the minimum distance h2 between the other side edge of the auxiliary hole and the adjacent second side.

[0010] In one embodiment, 2c≥a≥c.

[0011] In one embodiment, h1 < b ≤ 0.5c.

[0012] In one embodiment, the shape of the second side corresponds to the shape of the side edge of the auxiliary hole.

[0013] In one embodiment, the side edge of the auxiliary hole includes at least one first line segment, and the second side includes at least one second line segment; wherein each second line segment is disposed corresponding to a first line segment and is parallel to each other.

[0014] In one embodiment, the shape of the second side does not correspond to the shape of the side edge of the auxiliary hole.

[0015] A rotor includes a rotor core and a permanent magnet, the permanent magnet being installed inside the rotor core, the rotor core being any of the rotor cores described above.

[0016] A permanent magnet synchronous motor includes a stator and a rotor, wherein the rotor is the rotor described above.

[0017] The aforementioned rotor core, by setting auxiliary holes between adjacent magnetic isolation slots, ensures that the minimum distance h1 between the magnetic isolation slot and the periphery of the rotor core is less than or equal to the minimum distance h2 between the auxiliary hole and the adjacent magnetic isolation slot; and the volume and position of the auxiliary hole relative to the magnetic isolation slot satisfy the first condition to reduce eddy current losses in the magnet. After installing permanent magnets, the magnetic reluctance on the harmonic channels at both ends of the rotor's magnetic poles increases, thus hindering the formation of eddy currents on the surface of the permanent magnets and reducing eddy current losses. Furthermore, by limiting the position and size of the auxiliary holes, the effect of suppressing eddy current losses is even better, reducing eddy current losses by more than 55%. At the same time, the auxiliary holes are easy to process, and the motor performance is not significantly affected by the setting of the auxiliary holes. That is, while significantly suppressing the eddy current losses of the permanent magnets in the motor, the manufacturing difficulty and motor performance of the motor are taken into account, avoiding the phenomenon that existing methods of suppressing eddy current losses lead to difficulties in motor processing and manufacturing or a significant decrease in motor performance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the permanent magnet synchronous motor in the first embodiment of the present invention;

[0019] Figure 2 for Figure 1 A schematic diagram of the rotor structure of a permanent magnet synchronous motor;

[0020] Figure 3 for Figure 2 A schematic diagram of the rotor core of the intermediate rotor;

[0021] Figure 4 for Figure 2 A partial structural diagram of the central rotor;

[0022] Figure 5 for Figure 1 The relationship between eddy current loss of permanent magnet in permanent magnet synchronous motor and a;

[0023] Figure 6 for Figure 1 The relationship between eddy current loss of permanent magnet in permanent magnet synchronous motor and b;

[0024] Figure 7 for Figure 1 A partial structural diagram of a permanent magnet synchronous motor;

[0025] Figure 8 This is a partial structural schematic diagram of the permanent magnet synchronous motor in the first comparative example of the present invention;

[0026] Figure 9 This is a comparison diagram of the eddy current losses of the permanent magnets in the permanent magnet synchronous motors of the first embodiment and the first comparative example of the present invention;

[0027] Figure 10This is a partial structural schematic diagram of the permanent magnet synchronous motor in the second comparative example of the present invention;

[0028] Figure 11 This is a comparison diagram of the eddy current losses of the permanent magnets in the permanent magnet synchronous motors of the first embodiment and the second comparative example of the present invention.

[0029] Figure 12 This is a simulation diagram of the magnetic field around the magnetic isolation hole of the rotor of the permanent magnet synchronous motor in the second comparative example of the present invention.

[0030] Figure 13 This is a torque comparison diagram of the permanent magnet synchronous motors in the first embodiment and the second comparative example of the present invention;

[0031] Figure 14 This is a partial structural diagram of the rotor of the permanent magnet synchronous motor in the second embodiment of the present invention;

[0032] Figure 15 This is a partial structural diagram of the rotor of the permanent magnet synchronous motor in the third embodiment of the present invention;

[0033] Figure 16 This is a partial structural diagram of the rotor of the permanent magnet synchronous motor in the fourth embodiment of the present invention;

[0034] Figure 17 This is a partial structural diagram of the rotor of the permanent magnet synchronous motor in the fifth embodiment of the present invention;

[0035] Figure 18 This is a partial structural diagram of the rotor of the permanent magnet synchronous motor in the sixth embodiment of the present invention. Detailed Implementation

[0036] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0042] Please see Figure 1 , Figure 1 A schematic diagram of a permanent magnet synchronous motor 100 according to a first embodiment of the present invention is shown. The permanent magnet synchronous motor 100 provided in the first embodiment includes a stator 200 and a rotor 300. The rotor 300 is rotatable relative to the stator 200 and outputs torque. The rotor 300 is located in the shaft hole of the stator 200, and an air gap is formed between the outer surface of the rotor 300 and the inner surface of the stator 200. The stator 200 adopts a concentrated winding design; however, the winding design of the stator 200 is not limited to this. The specific structure of the stator 200 can be found in the prior art and will not be described in detail here. The specific structure of the rotor 300 is detailed below.

[0043] Combination Figure 2 , Figure 2 The schematic diagram of the rotor of the permanent magnet synchronous motor in this embodiment is shown. The rotor 300 includes a rotor core 310 and a permanent magnet 320. The permanent magnet 320 is installed inside the rotor core 310 to form a built-in structure (embedded structure). That is, the rotor 300 is the rotor of a built-in permanent magnet synchronous motor.

[0044] The rotor 300 is equipped with multiple sets of permanent magnets 320, which are evenly distributed circumferentially and arranged in a ring, meaning the rotor 300 adopts a non-tangential structure. The number of sets of permanent magnets 320 can be set according to actual needs, and their shape can also be determined based on specific requirements. In this embodiment, the rotor core 310 has eight sets of permanent magnets 320, each set arranged in a V-shape and comprising two permanent magnets 320. Each permanent magnet 320 can be a single piece or a modular combination. It should be noted that in other embodiments, the number of sets of permanent magnets 320 in the rotor 300 can be, but is not limited to, four, six, twelve, or more sets. Each set of permanent magnets 320 can be in a straight line, double V-shape, V-shape, or other shapes, depending on actual needs. The number of permanent magnets 320 in each set can be determined based on their shape and actual requirements.

[0045] In this embodiment, the permanent magnet 320 can be, but is not limited to, magnetic steel, including but not limited to AlNiCo magnets, Neodymium Iron Boron magnets, ferrite magnets, and Samarium Cobalt magnets.

[0046] Combination Figure 3 and Figure 4 , Figure 3 This diagram shows the structure of the rotor core of the permanent magnet synchronous motor in this embodiment. Figure 4 A partial structural schematic diagram of the rotor of the permanent magnet synchronous motor in this embodiment is shown. The rotor core 310 has a shaft hole 311 and multiple sets of magnet slots evenly distributed around the shaft hole 311. The multiple sets of magnet slots correspond one-to-one with multiple sets of permanent magnets 320, that is, each set of permanent magnets 320 is inserted into or embedded in a set of magnet slots to achieve internal (embedded) installation.

[0047] Each set of magnet slots includes a first magnet slot 330, meaning that several first magnet slots 330 are evenly distributed circumferentially along the shaft hole 311, and magnetic isolation slots 334 are formed at the ends of adjacent permanent magnets 320 where they have different magnetic poles. An auxiliary hole 340 is formed between adjacent magnetic isolation slots 334. The minimum distance h1 between the magnetic isolation slot 334 and the periphery 312 of the rotor core 310 is less than or equal to the minimum distance h2 between the auxiliary hole 340 and the adjacent magnetic isolation slot 334. Moreover, the volume and position of the auxiliary hole 340 relative to the magnetic isolation slot 334 satisfy a first condition to reduce magnet eddy current losses.

[0048] Because the concentrated winding of the stator 200 has a high air gap harmonic content, eddy current losses are easily formed on the surface of the rotor 300. By setting auxiliary holes 340 between adjacent magnetic isolation slots 334 and opening channels between adjacent magnetic poles of the rotor 300, the magnetic resistance on the harmonic channels at both ends of the magnetic poles is increased, thus hindering the formation of eddy currents on the surface of the permanent magnet 320 and reducing eddy current losses. Moreover, the auxiliary holes 340 are easy to manufacture, and the motor performance is not significantly affected by the setting of the auxiliary holes 340. That is, while significantly suppressing the eddy current losses of the permanent magnets of the motor, the manufacturing difficulty and motor performance of the motor are taken into account, avoiding the phenomenon that existing methods of suppressing eddy current losses lead to difficulties in motor manufacturing or a significant decrease in motor performance.

[0049] In this embodiment, the rotor 300 has eight sets of permanent magnets 320, and each set of permanent magnets 320 is arranged in a V-shape. Correspondingly, eight sets of magnetic slots are formed on the rotor core 310. Each set of magnetic slots includes a first magnetic slot 330, which is also V-shaped. It should be noted that the number of sets of magnetic slots is not limited to eight; it can also be four, six, twelve, or more sets. Furthermore, the number and shape of the magnetic slots in each set of magnetic slots 330 depend on each set of permanent magnets 320. It is understood that in other embodiments, each set of magnetic slots includes a first magnetic slot, which is in a straight line shape; or each set of magnetic slots includes a first magnetic slot and a second magnetic slot, both of which are V-shaped, or the first magnetic slot is V-shaped and the second magnetic slot is in a straight line shape.

[0050] In this embodiment, the rotor core 310 includes multiple rotor laminations. Each rotor lamination has a first through hole and a second through hole. The first through hole corresponds to the first magnet slot 330, and the second through hole corresponds to the auxiliary hole 340. When assembling the rotor core 310, the multiple rotor laminations are stacked and laminated sequentially to form the rotor core 310. The first through holes of all rotor laminations are connected to form the first magnet slot 330, and the second through holes of all rotor laminations are connected to form the auxiliary hole 340. It can be understood that in other embodiments, the rotor core 310 is an integral structure, not a laminated structure, and the first magnet slot 330 and the auxiliary hole 340 are directly formed on the integral structure.

[0051] The magnetic isolation groove 334 has a first side 336 and a second side 338, and the auxiliary hole 340 has a side edge 342 close to the magnetic isolation groove 334 in the circumferential direction. The first side 336 is provided corresponding to the periphery 312, and the minimum distance between it and the periphery 312 is the aforementioned minimum distance h1. The second side 338 is provided corresponding to the side edge 342 of the auxiliary hole 340, and the minimum distance between it and the side edge 342 of the auxiliary hole 340 is the aforementioned minimum distance h2. The maximum radial length of the auxiliary hole 340 is a, the minimum radial distance between the auxiliary hole 340 and the periphery 312 is b, the radial length of the second side 338 is c, and the maximum circumferential length of the auxiliary hole 340 is d. The first condition includes 2c ≥ a ≥ 0.5c, and h1 < b ≤ c. Compared to a motor without an auxiliary hole, when h2 ≥ h1, by further restricting the position and size of the auxiliary hole 340, eddy current losses can be further suppressed, and eddy current losses can be reduced by more than 55%.

[0052] To further enhance the suppression of eddy current losses, the values ​​of h1, h2, b, and c are kept constant when h2 ≥ h1, and the range of a is further limited to: 2c ≥ a ≥ c. Within this range, as a increases, the eddy current losses of the permanent magnet in the motor show a decreasing trend, and the eddy current losses are reduced by at least 72%.

[0053] To further enhance the suppression of eddy current losses, the values ​​of h1, h2, a, and c are kept constant when h2 ≥ h1, and the range of b is further limited to h1 < b ≤ 0.5c. Within this range, the eddy current losses of the permanent magnet in the motor can be controlled at a low level, achieving a reduction of over 72% in eddy current losses.

[0054] In this embodiment, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338, so that the minimum distance between the two side edges 342 of the auxiliary hole 340 and the magnetic isolation groove 334 is equidistant.

[0055] The shape of the second side 338 corresponds to the shape of the side edge 342 of the auxiliary hole 340. That is, in order to adapt to the shape change of the auxiliary hole 340, the shape of the second side 338 is adjusted accordingly so that the shapes of the two correspond (adapt) and thus form a channel between them, that is, a channel is formed between the auxiliary hole 340 and the magnetic isolation groove 334. This channel is also called a magnetic isolation bridge. The narrower it is, the smaller the cross-axis and direct-axis harmonic channels near the two ends of the magnetic pole, which can better block harmonics from reaching the surface of the permanent magnet 320 and suppress eddy current losses.

[0056] Furthermore, the side edge 342 of the auxiliary hole 340 includes at least one first line segment 346. The second side 338 includes at least one second line segment 339. Each second line segment 339 is provided corresponding to a first line segment 346 and is parallel to each other, so that the curved or straight segment of the side edge 342 of the auxiliary hole 340 and the curved or straight segment of the magnetic isolation groove 334 form a parallel channel 314. The narrower the parallel channel 314, the better the eddy current suppression effect, but ultimately h2 ≥ h1 should be guaranteed.

[0057] In this embodiment, the auxiliary hole 340 is square, meaning its side edge 342 is straight and includes a first line segment 346; correspondingly, the second side 338 is also straight and includes a second line segment 339. The first line segment 346 and the second line segment 339 are parallel to each other, meaning the side edge 342 of the auxiliary hole 340 and the second side 338 are parallel to each other. The maximum circumferential length d of the auxiliary hole 340 can be set according to actual needs, but it should be avoided to be too large, i.e., h2≥h1 should be ensured.

[0058] Combination Figure 5 , Figure 5The diagram illustrates the relationship between eddy current loss and a in the permanent magnet of the permanent magnet synchronous motor in this embodiment. Assume that in this embodiment, h1 = h2 = 1 mm, a = 1 mm to 10 mm, b = 1.6 mm, c = 4.9 mm, and d = 6 mm. Compared to a permanent magnet synchronous motor with the same values ​​and no openings, the eddy current loss of the permanent magnet in this motor is 15.3 W. When 10 mm ≥ a ≥ 2.5 mm, the eddy current loss drops below 5.8 W, meaning it decreases by at least 62%. When 10 mm ≥ a ≥ 4.9 mm, the eddy current loss further decreases below 4.26 W, meaning it decreases by at least 72%. Therefore, as a increases, the eddy current loss first decreases linearly and then stabilizes. When 2c ≥ a ≥ 0.5c, the eddy current loss can be reduced by at least 50%; when 2c ≥ a ≥ c, the eddy current loss can be reduced by at least 72%. It should be noted that, in order to better illustrate the relationship between the size of 'a' and the eddy current loss value, the above values ​​are merely exemplary and hypothetical, and do not necessarily constitute a limitation on the relevant dimensions of the permanent magnet synchronous motor 100 in this embodiment.

[0059] Combination Figure 6 , Figure 6 The diagram illustrates the relationship between eddy current loss and b in the permanent magnet of the permanent magnet synchronous motor in this embodiment. Assume that in this embodiment, h1 = h2 = 1 mm, a = 4 mm, b = 1 mm to 10 mm, c = 4.9 mm, and d = 6 mm. Compared to a permanent magnet synchronous motor with the same values ​​and no openings, the eddy current loss of the permanent magnet in this motor is 15.3 W. When 1 mm < b ≤ 5.1 mm, the eddy current loss drops below 6.98 W, meaning it decreases by at least 54%. When 1 mm < b ≤ 2.6 mm, the eddy current loss further decreases below 4.26 W, meaning it decreases by at least 72%. Therefore, as b increases, the eddy current loss first decreases slightly and then gradually increases. When h1 < b ≤ c, the eddy current loss can be reduced by at least 54%; when h1 < b ≤ 0.5 c, the eddy current loss can be reduced by at least 72%. It should be noted that, in order to better illustrate the relationship between the size of b and the eddy current loss value, the above values ​​are merely exemplary and hypothetical, and do not necessarily constitute a limitation on the relevant dimensions of the permanent magnet synchronous motor 100 in this embodiment.

[0060] Therefore, according to Figure 5 and Figure 6 In this embodiment, the position and size of the auxiliary hole 340 are further restricted to: h2≥h1, 2c≥a≥c, and h1<b≤0.5c; at this time, the eddy current loss of the permanent magnet 320 of the permanent magnet synchronous motor 100 can be reduced by at least 72%.

[0061] Combination Figures 7 to 9 , Figure 7A partial structural schematic diagram of the permanent magnet synchronous motor in this embodiment is shown. Figure 8 A partial structural schematic diagram of the permanent magnet synchronous motor in the first comparative example of the present invention is shown. Figure 9 This diagram shows a comparison of eddy current losses in the permanent magnets of the permanent magnet synchronous motors in this embodiment and the first comparative example. Figure 7 and Figure 8 It can be seen that the rotor core 310 of the first comparative permanent magnet synchronous motor 100 does not have auxiliary holes, but other aspects are the same as those of the permanent magnet synchronous motor 100 in this embodiment.

[0062] from Figure 9 As can be seen, the fluctuation range of the eddy current loss curve of the permanent magnet 320 in the first comparative permanent magnet synchronous motor 100 is much larger than that of the eddy current loss curve of the permanent magnet 320 in this embodiment. Specifically, the average value of the eddy current loss of the permanent magnet 320 in the first comparative permanent magnet synchronous motor 100 is 15.33W, while the average value of the eddy current loss of the permanent magnet 320 in this embodiment is 6.88W. Therefore, compared with the first comparative example, the permanent magnet synchronous motor 100 in this embodiment significantly reduces eddy current loss, and at least by 55%.

[0063] The data on eddy current losses and motor performance indicators of the first comparative permanent magnet synchronous motor 100 and the permanent magnet synchronous motor 100 of this embodiment are detailed in Table 1 below.

[0064] Eddy current loss (W) 15.3 6.9 back electromotive force distortion rate 0.4％ 0.4％ RMS value of back electromotive force (V) 339.5 339.5 Cogging torque (Nm) 0.04 0.04 Torque (Nm) 6.9 6.8 Torque ripple 10.5％ 3.8％

[0065] Table 1. Values ​​of eddy current losses and motor performance indicators of the permanent magnet synchronous motor 100 in the first comparative example and this embodiment.

[0066] As shown in Table 1 above, compared to the first comparative permanent magnet synchronous motor 100, the eddy current loss of the permanent magnet 320 in this embodiment of the permanent magnet synchronous motor 100 is 6.9W, a reduction of 55%. Furthermore, the back EMF distortion rate, effective back EMF value, and cogging torque of this embodiment of the permanent magnet synchronous motor 100 remain unchanged, i.e., they are not affected by the auxiliary hole 340. The torque fluctuation rate is reduced from 10.5% to 3.8%, but because it also obstructs the cross-axis path of the magnetic field, the torque is only reduced by 0.1Nm under the same current, i.e., a reduction of 1.5%. Therefore, this embodiment of the permanent magnet synchronous motor 100 significantly reduces eddy current losses without significantly affecting its motor performance, ensuring motor performance. At the same time, the auxiliary hole 340 is easy to create and does not increase the manufacturing difficulty of the motor. Therefore, this embodiment of the permanent magnet synchronous motor 100 effectively suppresses eddy current losses while balancing motor performance and manufacturing difficulty.

[0067] Combination Figure 8 and Figure 10 , Figure 10 A partial structural schematic diagram of the permanent magnet synchronous motor in the second comparative example of the present invention is shown. Based on the permanent magnet synchronous motor 100 in this embodiment, the rotor core 310 of the second comparative example permanent magnet synchronous motor 100 is provided with magnetic isolation holes 316. That is, two magnetic isolation holes 316 are opened in the area between each set of permanent magnets 320 and the periphery 312 of the rotor core 310. Each magnetic isolation hole 316 is set close to the magnetic isolation groove 334 (the end 332 of the first magnet groove 330).

[0068] Combination Figures 11 to 13 , Figure 11 The diagram shows a comparison of eddy current losses in the permanent magnets of the permanent magnet synchronous motors in the first embodiment and the second comparative example of the present invention. Figure 12 A simulation diagram of the magnetic field around the magnetic isolation hole of the rotor of the permanent magnet synchronous motor in the second comparative example of the present invention is shown. Figure 13 This diagram shows a torque comparison of the permanent magnet synchronous motors in the first embodiment and the second comparative example of the present invention. Figure 11 It can be seen that the eddy current loss curves of the permanent magnet 320 of the permanent magnet synchronous motor 100 in the first embodiment and the second comparative example almost overlap, that is, the eddy current loss of the permanent magnet 320 of the permanent magnet synchronous motor 100 in the second comparative example has not been improved.

[0069] according to Figure 12 It can be seen that, due to the addition of the magnetic isolation hole 316 above the permanent magnet 320, and the air filling the magnetic isolation hole 316, air is not easily magnetic, thus hindering the magnetic reluctance in the direction of the magnetic field of the permanent magnet 320 of the rotor 300. Furthermore, from... Figure 13 As can be seen, the fluctuation range of the torque curve of the permanent magnet synchronous motor 100 in the second comparative example is smaller than that of the permanent magnet synchronous motor 100 in this embodiment. That is, the torque of the permanent magnet synchronous motor 100 in the second comparative example is reduced to a certain extent. Combined with the above analysis, since the magnetic isolation hole 316 hinders the magnetic reluctance in the direction of the magnetic field of the permanent magnet 320 of the rotor 300, the output force is reduced, which leads to the decrease in torque. Therefore, the permanent magnet synchronous motor 100 in this embodiment takes into account eddy current loss suppression, motor performance, and motor manufacturing difficulty, and achieves a significant reduction in eddy current loss while ensuring its good motor performance and manufacturability.

[0070] Please see Figure 14 , Figure 14 A partial structural schematic diagram of the rotor of the permanent magnet synchronous motor in the second embodiment of the present invention is shown. The permanent magnet synchronous motor 100 in this embodiment differs from the permanent magnet synchronous motor 100 in the first embodiment described above in the following ways:

[0071] The minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is not equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338, i.e., h2_1 < h2_2. This creates a skewed pole effect, reducing eddy current losses and the torque ripple rate of the motor, thereby reducing motor noise and vibration. It should be noted that in other embodiments, h2_1 > h2_2 can be set, which can also achieve the above-mentioned technical effects; moreover, the auxiliary hole 340 is not limited to a square hole, but can also be rhomboid, T-shaped, circular, elliptical, or other shapes.

[0072] As for the other aspects of the permanent magnet synchronous motor 100 in this embodiment, they are basically the same as the other aspects of the permanent magnet synchronous motor 100 in the first embodiment described above. The specific details can be referred to the description of the first embodiment described above, and will not be repeated here.

[0073] Please see Figure 15 , Figure 15 A partial structural schematic diagram of the rotor of the permanent magnet synchronous motor in the third embodiment of the present invention is shown. The permanent magnet synchronous motor 100 in this embodiment differs from the permanent magnet synchronous motor 100 in the first embodiment described above in the following ways:

[0074] The auxiliary hole 340 is prismatic, meaning its side edge 342 is convex. The second side 338 is concave, and the shape of the second side 338 is set to correspond to the shape of the side edge 342 of the auxiliary hole 340. This forms a channel (magnetic bridge) between the auxiliary hole 340 and the magnetic isolation groove 334. The narrower this channel, the smaller the cross-axis and direct-axis harmonic channels near the two ends of the magnetic pole, which can better prevent harmonics from reaching the surface of the permanent magnet 320 and suppress eddy current losses.

[0075] The side edge 342 of the auxiliary hole 340 includes two first line segments 346, which are connected to form an included angle. The second side 338 also includes two second line segments 339, which are connected to form an included angle. Each second line segment 339 corresponds to one first line segment 346 and they are parallel to each other. That is, the side edge 342 of the auxiliary hole 340 and the second side 338 are parallel to each other, forming a parallel channel 314. The narrower the parallel channel 314, the better the eddy current suppression effect, but ultimately h2 ≥ h1 should be guaranteed.

[0076] In this embodiment, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338. However, in other embodiments, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is not equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338, that is, h2_1 > h2_2 or h2_1 < h2_2.

[0077] As for the other aspects of the permanent magnet synchronous motor 100 in this embodiment, they are basically the same as the other aspects of the permanent magnet synchronous motor 100 in the first embodiment described above. The specific details can be referred to the description of the first embodiment described above, and will not be repeated here.

[0078] Please see Figure 16 , Figure 16 A partial structural schematic diagram of the rotor of the permanent magnet synchronous motor in the fourth embodiment of the present invention is shown. The permanent magnet synchronous motor 100 in this embodiment differs from the permanent magnet synchronous motor 100 in the first embodiment described above in the following ways:

[0079] The auxiliary hole 340 is T-shaped, meaning its side edge 342 is stepped. The second side 338 is also stepped, and the shape of the second side 338 is set to correspond to the shape of the side edge 342 of the auxiliary hole 340. This forms a channel (magnetic bridge) between the auxiliary hole 340 and the magnetic isolation groove 334. The narrower this channel, the smaller the cross-axis and direct-axis harmonic channels near the two ends of the magnetic pole, which can better prevent harmonics from reaching the surface of the permanent magnet 320 and suppress eddy current losses.

[0080] The side edge 342 of the auxiliary hole 340 includes three first line segments 346, which are connected sequentially to form a stepped shape. The second side 338 also includes three second line segments 339, which are connected sequentially to form a stepped shape. Each second line segment 339 corresponds to one first line segment 346 and is parallel to each other. That is, the side edge 342 of the auxiliary hole 340 and the second side 338 are parallel to each other, forming a parallel channel 314. The narrower the parallel channel 314, the better the eddy current suppression effect, but ultimately h2 ≥ h1 should be ensured.

[0081] In this embodiment, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338. However, in other embodiments, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is not equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338, that is, h2_1 > h2_2 or h2_1 < h2_2.

[0082] As for the other aspects of the permanent magnet synchronous motor 100 in this embodiment, they are basically the same as the other aspects of the permanent magnet synchronous motor 100 in the first embodiment described above. The specific details can be referred to the description of the first embodiment described above, and will not be repeated here.

[0083] Please see Figure 17 , Figure 17 A partial structural schematic diagram of the rotor of the permanent magnet synchronous motor in the fifth embodiment of the present invention is shown. The permanent magnet synchronous motor 100 in this embodiment differs from the permanent magnet synchronous motor 100 in the first embodiment described above in the following ways:

[0084] The auxiliary hole 340 is elliptical, meaning its side edge 342 is arc-shaped. The second side 338 is also arc-shaped, and its shape corresponds to the shape of the side edge 342 of the auxiliary hole 340. This forms a channel (magnetic bridge) between the auxiliary hole 340 and the magnetic isolation groove 334. The narrower this channel, the smaller the cross-axis and direct-axis harmonic channels near the two ends of the magnetic pole, which can better prevent harmonics from reaching the surface of the permanent magnet 320 and suppress eddy current losses.

[0085] The side edge 342 of the auxiliary hole 340 includes a first line segment 346, which is elliptical in shape. The second side 338 also includes a second line segment 339, which is also elliptical in shape. The second line segment 339 is positioned corresponding to the first line segment 346 and is parallel to it. That is, the side edge 342 of the auxiliary hole 340 and the second side 338 are parallel to each other, forming a parallel channel 314. The narrower the parallel channel 314, the better the eddy current suppression effect, but ultimately, h2 ≥ h1 should be ensured.

[0086] In this embodiment, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338.

[0087] It should be noted that in other embodiments, the auxiliary hole 340 is circular, meaning its side edge 342 is arc-shaped. The second side 338 is also arc-shaped, and by making the side edge 342 (first line segment 346) of the auxiliary hole 340 parallel to the second side 338 (second line segment 339), the aforementioned technical effect can also be achieved. Moreover, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is not equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338, i.e., h2_1 > h2_2 or h2_1 < h2_2.

[0088] As for the other aspects of the permanent magnet synchronous motor 100 in this embodiment, they are basically the same as the other aspects of the permanent magnet synchronous motor 100 in the first embodiment described above. The specific details can be referred to the description of the first embodiment described above, and will not be repeated here.

[0089] Please see Figure 18 , Figure 18 A partial structural schematic diagram of the rotor of the permanent magnet synchronous motor in the sixth embodiment of the present invention is shown. The permanent magnet synchronous motor 100 in this embodiment differs from the permanent magnet synchronous motor 100 in the first embodiment described above in the following ways:

[0090] The shape of the second side 338 of the rotor 300 of the permanent magnet synchronous motor 100 is not the same as the shape of the side edge 342 of the auxiliary hole 340. That is, the shape of the second side 338 is significantly different from the shape of the side edge 342 of the auxiliary hole 340. It can also achieve the purpose of this invention, but its effect of suppressing eddy current loss is not as good as the above embodiment.

[0091] Furthermore, the auxiliary hole 340 is prismatic, meaning its side edge 342 is convex. However, the second side 338 is straight, causing the shape of the second side 338 to not correspond to the shape of the side edge 342 of the auxiliary hole 340, thus making it impossible to form a parallel channel.

[0092] In this embodiment, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338. However, in other embodiments, the minimum distance h2 between one side edge 342 of the auxiliary hole 340 and the adjacent second side 338 is not equal to the minimum distance h2 between the other side edge 342 of the auxiliary hole 340 and the adjacent second side 338, that is, h2_1 > h2_2 or h2_1 < h2_2; moreover, the auxiliary hole 340 may also be T-shaped, elliptical, circular or other shapes.

[0093] As for the other aspects of the permanent magnet synchronous motor 100 in this embodiment, they are basically the same as the other aspects of the permanent magnet synchronous motor 100 in the first embodiment described above. The specific details can be referred to the description of the first embodiment described above, and will not be repeated here.

[0094] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A rotor core, wherein the rotor core has a shaft hole and a plurality of first magnetic steel slots evenly distributed circumferentially along the shaft hole, the first magnetic steel slots being adapted to accommodate permanent magnets, and wherein magnetic isolation slots are formed at the ends of adjacent permanent magnets where they have different magnetic poles; characterized in that, An auxiliary hole is provided between adjacent magnetic shielding slots; The magnetic shielding groove has a first side and a second side, and the auxiliary hole has a side edge close to the magnetic shielding groove in the circumferential direction; The first side is provided corresponding to the periphery of the rotor core, and the minimum distance between it and the periphery is h1; the second side is provided corresponding to the side edge of the auxiliary hole, its radial length is c, and the minimum distance between it and the side edge of the auxiliary hole is h2, h1≤h2; Wherein, the maximum radial length of the auxiliary hole is a; the minimum radial distance between the auxiliary hole and the periphery is b; the volume and position of the auxiliary hole relative to the magnetic isolation groove satisfy a first condition to reduce the eddy current loss of the magnet, the first condition including 2c≥a≥0.5c, and h1<b≤c.

2. The rotor core according to claim 1, characterized in that, The minimum distance h2 between one side edge of the auxiliary hole and the adjacent second side is greater than or less than the minimum distance h2 between the other side edge of the auxiliary hole and the adjacent second side.

3. The rotor core according to claim 1 or 2, characterized in that, 2c≥a≥c.

4. The rotor core according to claim 1 or 2, characterized in that, h1<b≤0.5c.

5. The rotor core according to claim 1 or 2, characterized in that, The shape of the second side corresponds to the shape of the side edge of the auxiliary hole.

6. The rotor core according to claim 5, characterized in that, The side edge of the auxiliary hole includes at least one first line segment, and the second side includes at least one second line segment; Each of the second line segments corresponds to a first line segment and they are parallel to each other.

7. The rotor core according to claim 1 or 2, characterized in that, The shape of the second side does not correspond to the shape of the side edge of the auxiliary hole.

8. A rotor comprising a rotor core and a permanent magnet, wherein the permanent magnet is mounted within the rotor core, characterized in that, The rotor core is the rotor core as described in any one of claims 1 to 7.

9. A permanent magnet synchronous motor, comprising a stator and a rotor, characterized in that, The rotor is the rotor as described in claim 8.

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