Improved double air gap Surface Permanent Magnet Synchronous Motor

Abstract

The present invention relates to an improved double-air gap surface permanent magnet synchronous motor, and more specifically, to an improved double-air gap surface permanent magnet synchronous motor that has high efficiency and high power density satisfying IEC international efficiency class IE5 while improving torque performance by implementing a dual structure of the rotor and stator. An improved double-air-gap surface permanent magnet synchronous motor according to an embodiment of the present invention comprises: a first stator having a first 'T'-shaped projection formed along a first inner surface; a first rotor having a first outer surface formed facing the first inner surface; a first permanent magnet arranged along the first outer surface; a second rotor having a second inner surface formed integrally connected to the first rotor inwardly and corresponding to the first rotor; a second permanent magnet arranged along the second inner surface; and a second stator having a second 'T'-shaped projection formed along a second outer surface formed facing the second inner surface. A first air gap portion of a predetermined space is formed between the first stator and the first rotor, and a second air gap portion of a predetermined space is formed between the second stator and the second rotor; the first permanent magnet has N poles and S poles alternately arranged at equal intervals along the first outer surface, and the second permanent magnet has N poles and S poles alternately arranged at equal intervals along the second inner surface, arranged with opposite polarity to the first permanent magnet; the first protrusion portion is formed in the same number as the second protrusion portion, and the first permanent magnet is formed in the same number as the second permanent magnet but is smaller than the number of the first protrusion portion.

Description

Technology Field

[0001] The present invention relates to an improved double-air gap surface permanent magnet synchronous motor, and more specifically, to an improved double-air gap surface permanent magnet synchronous motor that has high efficiency and high power density satisfying IEC international efficiency class IE5 while improving torque performance by implementing the rotor and stator structures in a double pair. Background Technology

[0002] Generally, a motor is a device that converts electrical energy into mechanical energy to obtain rotational force, and it is widely used in household electronic products as well as industrial equipment, and is broadly divided into DC motors and AC motors.

[0003] In other words, as production processes are automated and made more precise to improve productivity, AC / DC motors are being widely used in various industries.

[0004] Surface Permanent (Multi-phase) Synchronous Motor (SPMSM) is a motor in which the rotor is made of permanent magnets and the stator is composed of an armature with windings wound around a core. It is classified as an SPMSM if the shape of the back EMF generated while the motor rotates is a sinusoidal wave, and as a BLDC (brushless direct current) motor if it is a square wave.

[0005] In addition, motors are classified according to the arrangement of permanent magnets in the rotor into Interior Permanent Magnet (IPM) motors, in which permanent magnets are embedded in the rotor core, and Surface Permanent Magnet (SPM) motors, in which permanent magnets are arranged on the surface of the rotor core.

[0007] A conventional surface-mounted magnet type motor is described as follows with reference to the attached drawings.

[0008] FIG. 1 is a plan view illustrating a surface-mounted magnet type motor according to conventional technology.

[0009] As described above, a conventional surface-mounted magnet type motor (10) is installed such that a rotor (13) is rotatably mounted on a shaft (14) with an air gap inside a stator (12) on which a coil (not shown) is wound, and a plurality of permanent magnets (15) are arranged and fixed along the circumference of the outer surface of the rotor (13).

[0010] The stator (12) has a plurality of teeth (12b) formed protruding at regular intervals along the inner surface of a yoke portion (12a) having a circular ring shape, and a coil (not shown) is wound around each tooth (12b) and fixed to the housing (not shown) of the motor (10).

[0012] The rotor (13) is manufactured by stacking multiple silicon steel plates, and a shaft hole (13a) is formed so that a shaft (14) passes through and is fixed in the center, and a magnet mounting groove (13b) is formed along the circumference of the outer surface, and a permanent magnet (15) is fixed by press-fitting in each magnet mounting groove (13b).

[0013] In this conventional surface-mounted magnet type motor (10), when an AC power source is applied to a coil (not shown), a magnetic flux is generated in a direction perpendicular to the shaft (14) and rotates, and this rotating magnetic flux generates torque on the rotor (13) by the magnetic flux of a permanent magnet (15) located on the surface of the rotor (13), thereby rotating the rotor (13).

[0015] Meanwhile, as climate change caused by excessive greenhouse gas emissions becomes a serious issue, the paradigm of energy policy is rapidly shifting toward energy demand management, such as energy conservation and improved efficiency to reduce greenhouse gas emissions.

[0016] Motors account for more than 54% of total power consumption.

[0017] With the advancement of core motor technologies, performance improvements such as miniaturization, weight reduction, low noise, low vibration, and high efficiency are steadily being achieved; furthermore, there is a continuous demand for efficiency enhancement as an effective means of energy conservation and greenhouse gas emission reduction following the entry into force of the new climate agreement.

[0018] Figure 2 shows the International Electrotechnical Commission (IEC) international efficiency ratings, and there is an urgent need for a surface-mounted magnet type motor that can satisfy the IE5 rating by improving conventional technology. Prior art literature

[0019] Korean Registered Patent Publication No. 10-1332523, Title of Invention "Electric motor with structure dividing permanent magnet array of rotor" (Date of publication: Nov. 22, 2013) The problem to be solved

[0020] The present invention was created out of the aforementioned necessity, and aims to provide an improved double-air gap surface permanent magnet synchronous motor capable of achieving high efficiency and high power density satisfying the IEC International Efficiency Class IE5 while improving torque performance by implementing the rotor and stator structures in a double pair. means of solving the problem

[0021] To achieve the above-mentioned objective, an improved double-air-gap surface permanent magnet synchronous motor according to an embodiment of the present invention comprises: a first stator having a first 'T'-shaped projection formed along a first inner surface; a first rotor having a first outer surface formed facing the first inner surface; a first permanent magnet arranged along the first outer surface; a second rotor having a second inner surface formed integrally connected to the first rotor inwardly and corresponding to the first rotor; a second permanent magnet arranged along the second inner surface; and a second stator having a second 'T'-shaped projection formed along a second outer surface formed facing the second inner surface.

[0022] A first air gap portion of a predetermined space is formed between the first stator and the first rotor, and a second air gap portion of a predetermined space is formed between the second stator and the second rotor; the first permanent magnet has N poles and S poles alternately arranged at equal intervals along the first outer surface, and the second permanent magnet has N poles and S poles alternately arranged at equal intervals along the second inner surface, arranged with opposite polarity to the first permanent magnet; the first protrusion portion is formed in the same number as the second protrusion portion, and the first permanent magnet is formed in the same number as the second permanent magnet but is smaller than the number of the first protrusion portion. Effects of the invention

[0023] According to the present invention, since it has a double-hole structure, it has the advantage of having high power density and torque.

[0024] In addition, due to the double-hole structure, there is an advantage of being able to lower the cogging torque compared to conventional methods.

[0025] In addition, there is an advantage of increasing efficiency by improving the material of the double porous structure under the same conditions. Brief explanation of the drawing

[0026] FIG. 1 is a drawing illustrating a surface-mounted magnet type motor according to conventional technology. Figure 2 is a diagram showing the IEC (International Electrotechnical Commission) international efficiency ratings. FIG. 3 is an exemplary cross-sectional view illustrating a conventional SPMSM and a proposed dual-pore type SPMSM. Figure 4 is a graph showing the back electromotive force of a conventional SPMSM and a proposed double-air gap type SPMSM. Figure 5 is a graph showing the cogging torque of a conventional SPMSM and a proposed double-hole type SPMSM. Figure 6 is a graph showing the core loss (iron loss) of a conventional SPMSM and a proposed double-hole type SPMSM. Figure 7 is a graph showing the magnetic flux density of a conventional SPMSM and a proposed double-air gap type SPMSM. Figure 8 is a graph showing the permanent magnet losses of a conventional SPMSM and a proposed double-air gap type SPMSM. Figure 9 is a graph showing the torque of a conventional SPMSM and a proposed double-hole type SPMSM. FIG. 10 is a drawing showing the specifications (spec) of a conventional SPMSM (Ⅰ). Figure 11 is a graph showing the result value of a conventional SPMSM (I). Figure 12 is a drawing showing the specifications (spec) of a conventional SPMSM (II). Figure 13 is a graph showing the result value of a conventional SPMSM (II). Figure 12 is a drawing showing the specifications (spec) of a conventional SPMSM (II, III). Figure 13 is a graph showing the result value of a conventional SPMSM (II). Figure 14 is a graph showing the result value of a conventional SPMSM (III). FIG. 15 is a drawing showing the specifications (spec) of the proposed double-hole type SPMSM (IV). Figure 16 is a graph showing the results of the proposed double-pore type SPMSM (IV). Figure 17 is a drawing showing the specifications (spec) of the proposed double-hole type SPMSM (V). Figure 18 is a graph showing the results of the proposed double-pore type SPMSM (V). FIG. 19 is an exemplary cross-sectional view illustrating a double-pore type SPMSM according to an embodiment of the present invention. FIG. 20 is an enlarged view of the "Q" portion of FIG. 19. FIG. 21 is an exemplary cross-sectional view illustrating an improved double-pore type SPMSM according to an embodiment of the present invention. FIG. 22 is a diagram showing the magnetic flux direction to explain an improved double-air gap type SPMSM according to an embodiment of the present invention. FIG. 23 is a diagram showing the winding direction for phase A, exemplarily among the three phases, to explain an improved double-air gap type SPMSM according to an embodiment of the present invention. FIGS. 24 and 25 are circuit diagrams for illustrating an improved double-air type SPMSM according to an embodiment of the present invention. FIG. 26 is an exemplary drawing illustrating a bulkhead portion of an improved double-hole type SPMSM according to an embodiment of the present invention. Specific details for implementing the invention

[0027] Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0028] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. The meaning of "comprising" as used in the specification specifies a particular characteristic, area, integer, step, action, element, and / or component, and does not exclude the presence or addition of other particular characteristic, area, integer, step, action, element, component, and / or group.

[0029] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0030] The embodiments of the present invention described with reference to the drawings specifically illustrate ideal embodiments of the present invention. As a result, various variations of the illustrations, such as variations in manufacturing methods and / or specifications, are expected. Accordingly, the embodiments are not limited to specific forms of the illustrated areas and include variations in form, for example, by manufacturing. Areas illustrated or described as flat may generally have overlapping / rough and non-linear characteristics.

[0031] Additionally, parts depicted as having sharp angles may be rounded. Therefore, the areas depicted in the drawings are merely approximate, and their shapes are not intended to depict the exact shape of the areas, nor are they intended to narrow the scope of the invention.

[0032] It should be noted that the drawings are schematic and not drawn to scale. The relative dimensions and proportions of parts in the drawings are exaggerated or reduced in size for clarity and convenience in the drawings, and any dimensions are merely illustrative and not limiting. Additionally, the same reference numerals are used for the same structure, element, or part appearing in two or more drawings to indicate corresponding or similar features in different embodiments.

[0034] As there is a continuous demand for improved efficiency of motors (electric motors) that account for more than 54% of power consumption as an effective means of reducing greenhouse gases, the present invention proposes a design for a double-air-gap type SPMSM (Surface Permanent Magnet Synchronous Motor) having high efficiency and high power density that satisfies the International Electrotechnical Commission (IEC) international efficiency grade IE5.

[0035] Conventional Surface Permanent Magnet Synchronous Motors (SPMSMs) have an external or internal rotor structure in which the rotor is located externally or internally, as shown in Fig. 3 (a).

[0036] The structure proposed by the present invention has a double-air gap structure utilizing a rotor yoke as shown in Fig. 3 (b), in contrast to the internal-type structure of a conventional SPMSM as shown in Fig. 3 (a), in order to improve efficiency and power density.

[0037] The conventional structure and the proposed structure of the present invention were subjected to characteristic analysis using FEM (Finite Elements Method), and the results were compared as follows.

[0039] 1. 서 론

[0040] As climate change caused by excessive greenhouse gas emissions becomes a serious issue, the paradigm of energy policy is rapidly shifting toward energy demand management, including energy conservation and improved efficiency to reduce greenhouse gas emissions.

[0041] Motors account for more than 54% of total power consumption.

[0042] With the advancement of core motor technologies, performance improvements such as miniaturization, weight reduction, low noise, low vibration, and high efficiency are steadily being achieved; furthermore, continuous efficiency enhancement is required as an effective means of energy conservation and greenhouse gas emission reduction following the entry into force of the new climate agreement.

[0043] Figure 2 shows the International Electrotechnical Commission (IEC) international efficiency ratings, and the present invention proposes a double-air-gap type Surface Permanent Magnet Synchronous Motor (SPSM) designed to satisfy the IE5 rating.

[0044] According to the present invention, the efficiency and power density of conventional and proposed structures were characterized based on FEM, and their performance was compared.

[0046] 2. 본 론

[0047] 2.1 종래 및 제안된 SPMSM의 구조 및 특성해석

[0048] For the conventional and proposed SPMSMs, the stator outer diameter and stacking length are the same, and the detailed design structure of each is as shown in Table 1.

[0049] Parameter Value Unit Number of stator slots 24 slot Numberof poles 20 pole Stator outer diameter 200 mm Shaft outer diameter 20 mm Air-gap 0.8 mm PM height 4 mm Stack length 15 mm Number of turns per phase 16 turn Number of parallel paths 2 path Number of parallel wires(strands in hand) 10 turn

[0050] Figure 3 shows the structure of a conventional and proposed SPMSM having 24 slots and 20 poles.

[0051] For the materials of the conventional and proposed structures, POSCO's 35PN380 was applied for comparison.

[0052] In addition, for the proposed structure, 20PN1500 was additionally applied, and depending on the material, the material 35PN380 of the conventional SPMSM and the materials 35PN380 and 20PN1500 of the proposed SPMSM were characterized and their performance compared.

[0053] For reference, 35PN380 is a non-oriented electrical steel sheet produced by a company (POSCO), with a thickness of 0.35±0.05mm and a density of 7.65±0.1kg / cm³. 2 , iron loss 3.80 W / kg or less, magnetic flux density 1.62 or more, packing factor 95% or more, and has standard dimensions, magnetic properties, etc.

[0054] In addition, 20PN1500 is a non-oriented electrical steel sheet produced by a company (POSCO), with a thickness of 0.20±0.05mm and a density of 7.65±0.1kg / cm³ 2 , iron loss 15.0 W / kg or less, magnetic flux density 1.62 or more, packing factor 93% or more, and has standard dimensions, magnetic properties, etc.

[0056] Figure 4 is a diagram showing the back EMF of a conventional and proposed SPMSM. The maximum voltage of the conventional SPMSM is 12.01[V], and the maximum voltage of the proposed SPMSM 35PN380 is 20[V], and the maximum voltage of the 20PN1500 is 20.32[V].

[0058] Figure 5 shows the cogging torque of the conventional and proposed SPMSM.

[0059] In the case of a conventional SPMSM, the cogging torque is 145.68 [mNm], and in the case of the SPMSM proposed by the present invention, it is 102.37 [mNm] when the material is 35PN380 and 93.4 [mNm] when the material is 20PN1500.

[0060] Compared to the conventional case, the cogging torque of the proposed SPMSM with material 35PN380 was reduced by 29.7% compared to the conventional SPMSM, and the cogging torque of the SPMSM with material 20PN1500 was reduced by 35.9%.

[0062] Figure 6 shows the iron loss of conventional and proposed SPMSMs.

[0063] In the case of a conventional SPMSM, the iron loss is 51.52[W], and in the case of the SPMSM material 35PN380 proposed by the present invention, it is 91.4[W], and in the case of 20PN1500, it is 67.8[W].

[0064] Compared to conventional SPMSM, the iron loss increased by 43.6% for the material 35PN380 of the proposed SPMSM and by 24.01% for 20PN1500.

[0065] As shown in Fig. 7, it is determined that the iron loss increased due to the high magnetic flux density saturation of the iron core caused by the increased winding [Fig. 7 (a), (b)] compared to the conventional SPMSM [Fig. 7 (a)].

[0067] Figure 8 shows the permanent magnet losses of conventional and proposed SPMSMs.

[0068] The permanent magnet loss of the conventional SPMSM is 9.14[W], and the material of the proposed SPMSM, 35PN380, is 14.4[W] and the material of 20PN1500 is 17.78[W].

[0069] It is determined that the proposed SPMSM has increased permanent magnet loss due to the permanent magnet being increased by 1.7 times compared to conventional SPMSM.

[0070] The proposed SPMSM has increased permanent magnet loss with 20PN1500 material compared to 35PN380.

[0072] This is a result caused by the increased burden on the permanent magnet due to the low magnetic flux density saturation level of the iron core.

[0074] Figure 9 shows the rated torque of the conventional and proposed SPMSMs.

[0075] The rated torque of a conventional SPMSM is 4.42 [Nm].

[0076] Compared to conventional SPMSMs, the rated torque of the proposed SPMSM with material 35PN380 increased by 37% to 7.02 Nm, and the rated torque of the proposed SPMSM with material 20PN1500 increased by 36.67% to 6.98 Nm.

[0078] Table 2 below shows a performance comparison table of conventional and proposed SPMSMs.

[0079] Parameter Conventional (35PN380) Proposed (35PN380) Propoased (20PN1500) Stator current frequency, Hz 500 ← ← Rotor speed, rpm 3,000 ← ← Electromagnetic torque, Nm 4.42 7.02 6.98 Output power, W 1301.96 2058.35 2066.24 Input, power, W 1413.33 2249.65 2237.08 Efficiency, % 92.12 91.45 94.23 Wingding losses, W 24.7 44.25 44.25 Core losses, W 51.52 91.4 67.8 Losses in PMs, W 9.14 14.4 17.78 Mechanical losses, W 25.96 41.24 41.01 Stator current density, A / mm² 4.818 9.636 9.636 Mass of Cu, kg 0.4421 0.7032 0.7032 Mass of Fe, kg 0.1958 4.2376 4.2376 Mass of PM, kg 0.1958 0.4945 0.4945 Total mass, kg 4.4036 5.4353 5.4353 Power density, kW / kg 0.2956 0.3787 0.3801

[0080] In the conventional case, iron loss is 51.52[W], permanent magnet loss is 9.14[W], and mechanical loss is 25.96[W], which is lower than the proposed structure, while power density is 0.2956 kW / kg, which is lower than the proposed structure.

[0081] In the case of the proposed SPMSM material 35PN380, a higher power density of 0.3801 kW / kg is obtained compared to the conventional one, but the iron loss due to the double stator structure is 91.4 W, the permanent magnet loss is 14.4 W, and the mechanical loss is 41.24 W, so the efficiency is 91.45%, which is slightly lower than the conventional SPMSM by 0.72% but similar to the efficiency.

[0082] In the case of the proposed SPMSM material 20PN1500, the iron loss is 67.8%, which is higher than that of the conventional SPMSM, but the same output of 2066.24W as 35PN380 can be obtained, which is 37% higher than that of the conventional SPMSM.

[0083] In addition, the efficiency of the proposed SPMSM material 20PN1500 increased by 2.23% to 94.23%, and the power density increased by 22.23% to 0.3801 kW / kg.

[0085] Then, to explain in more detail, as shown in Fig. 10, the internal type [conventional SPMSM (I)] in which a rotor is configured with a permanent magnet facing the inner circumference of the stator among conventional SPMSMs is as follows.

[0086] SPMSM(Ⅰ) Parameter Value Stator current frequency, Hz 500 Rotor speed, rpm 3,000 Shaft torque, Nm 4.14 Electromagnetic torque, Nm 4.42 Shaft power(Output Power), W 1301.96 Input electric power, W (2π×(3000 / 60)×4.42)+(50×50×0.0033×3) 1413.33 Efficiency, % (1301.96 / 1413.33)×100 92.12 Winding losses, W (50×50×0.0033×3) 24.75 Core losses, W 51.52 Losses in PMs, W 9.14 Mechanical losses, W 25.96 Stator current, A rms 50 Stator current density, A / mm 2 (50 / 2) / (0.4064×0.4064×3.14)×10=4.818 4.818 Mass of Cu, kg 0.4421 Mass of Fe, kg (Stator_Fe(1.7886)+Rotor_Fe(1.9771)) 2.0937 Mass of PM, kg 0.1958 Total mass(Eim components), kg 4.4036 Power density, kW / kg (1.30196 / 4.4036) 0.2956

[0087] FIG. 10 shows the structure of a conventional SPMSM (I) having 24 slots and 20 poles.

[0088] In addition, the material of the conventional SPMSM (I) is 35PN380.

[0089] For reference, 35PN380 is a non-oriented electrical steel sheet produced by a company (POSCO), with a thickness of 0.35mm and a density of 7.65kg / cm³. 2, iron loss 3.80 W / kg or less, magnetic flux density 1.62 or more, packing factor 95% or more, and has standard dimensions, magnetic properties, etc.

[0090] FIG. 11 shows the back EMF, core loss, permanent magnet loss, and rated torque of a conventional SPMSM (Ⅰ).

[0091] In addition, the conventional SPMSM (I) has a back EMF of 12.01 [V], an iron loss of 51.52 [W], a permanent magnet loss of 9.14 [W], a cogging torque of 145.68 [mNm], and a rated torque of 4.42 [Nm].

[0092] In addition, the conventional SPMSM (I) yielded similar or lower results even in material 20PN1500.

[0094] Next, as shown in FIG. 12, the external rotor type [conventional SPMSM (II)] configured with a rotor facing the outer circumference of the stator among conventional SPMSMs is as follows.

[0095] The above conventional SPMSM (II) is formed in the direction in which the winding goes out, that is, in the direction in which torque collision occurs.

[0096] SPMSM(Ⅱ) Parameter Value Stator current frequency, Hz 500 Rotor speed, rpm 3,000 Shaft torque, Nm 5.27 Electromagnetic torque, Nm 5.69 Shaft power(output power), W 1656.49 Input electric power, W (2π×(3000 / 60)×5.69)+(50×50×0.0026×3) 1,807.06 Efficiency, % (1,656.49 / 1,807.06)×100% 91.66 Winding losses, W (50×50×0.0026)×3 19.5 Core losses, W 77.78 Losses in PMs, W 19.87 Mechanical losses, W 33.42 Stator current, A rms 50 Stator current density, A / mm 2 (50 / 2) / (0.4064×0.4064×3.14)×10=4.818 4.818 Mass of Cu, kg 0.2611 Mass of Fe, kg (Stator_Fe(1.6047)+Rotor_Fe(0.5392)) 2.1439 Mass of PM, kg 0.2987 Total mass(Eim components), kg 2.7037 Power density, kW / kg (1.65649 / 2.7037) 0.6126

[0097] FIG. 12 shows the structure of a conventional SPMSM (II) having 24 slots and 20 poles.

[0098] In addition, the material of the conventional SPMSM (II) is 35PN380.

[0099] FIG. 13 shows the back EMF, core loss, permanent magnet loss, and rated torque of a conventional SPMSM (II).

[0100] In addition, the conventional SPMSM (II) has a back EMF of 17.01 [V], an iron loss of 77.78 [W], a permanent magnet loss of 19.87 [W], and a rated torque of 5.69 [Nm], but in reality, it is canceled out by collision with the magnetic flux.

[0101] In addition, the conventional SPMSM (II) yielded similar or lower results even in material 20PN1500.

[0103] Next, the external rotor type [conventional SPMSM (III)], in which a rotor with a permanent magnet formed facing the outer surface of the stator among conventional SPMSMs, is as follows.

[0104] The above conventional SPMSM (III) is formed in the direction in which the winding enters.

[0105] SPMSM(Ⅲ) Parameter Value Stator current frequency, Hz 500 Rotor speed, rpm 3,000 Shaft torque, Nm 2.6 Electromagnetic torque, Nm 2.73 Shaft power(output power), W 817.75 Input electric power, W (2π×(3000 / 60)×2.73)+(50×50×0.0026×3) 877.15 Efficiency, % (817.75 / 877.15)×100% 93.22 Winding losses, W (50×50×0.0026)×3 19.5 Core losses, W 26.55 Losses in PMs, W 6.97 Mechanical losses, W 16.4 Stator current, A rms 50 Stator current density, A / mm 2 (50 / 2) / (0.4064×0.4064×3.14)×10=4.818 4.818 Mass of Cu, kg 0.2611 Mass of Fe, kg (Stator_Fe(1.6047)+Rotor_Fe(0.5392)) 2.1439 Mass of PM, kg 0.2987 Total mass(Eim components), kg 2.7037 Power density, kW / kg (0.81775 / 2.7037) 0.3024

[0106] FIG. 14 shows the back EMF, core loss, permanent magnet loss, and rated torque of a conventional SPMSM (III).

[0107] In addition, the conventional SPMSM (III) has a back EMF of 8.01 [V], an iron loss of 26.55 [W], a permanent magnet loss of 6.97 [W], a cogging torque of 50.68 [mNm], and a rated torque of 2.73 [Nm].

[0108] In addition, the conventional SPMSM (III) yielded similar or lower results even in material 20PN1500.

[0110] Next, as shown in FIG. 15, the proposed SPMSM (IV) is of the double-pore type and is as follows.

[0111] In addition, the proposed SPMSM (IV) has a pair of 24 slots and 20 poles.

[0112] Here, the material of the above SPMSM(IV) is 35PN380.

[0113] SPMSM(Ⅳ) Parameter Value Stator current frequency, Hz 500 Rotor speed, rpm 3,000 Shaft torque, Nm 6.55 Electromagnetic torque, Nm 7.02 Shaft power, W 2058.35 Input electric power, W (2π×(3000 / 60)×7.02)+(50×50×(0.0033+0.0026)×3) 2,249.65 Efficiency, % (2058.35 / 2,249.64)×100% 91.45 Winding losses, W (50×50×(0.0033+0.0026)×3) 44.25 Core losses, W 91.4 Losses in PMs, W 14.4 Mechanical losses, W 41.24 Stator current, A rms 50 Stator current density, A / mm 2 (50 / 2) / (0.4064×0.4064×3.14)×10×2=9.636 9.636 Mass of Cu, kg Outer_Stator_Cu(0.4421)+Inner_Rotor_Fe(0.2611) 0.7032 Mass of Fe, kg (Outer_Stator_Fe(1.7886)+Outer_Rotor_Fe(0.3051)+Inner_Stator_Fe(1.6047)+Inner_Rotor Fe(0.5392)) 2.0937+2.1439 = 4.2376 Mass of PM, kg Outer_Stator_PM(0.1958)+Inner_Rotor_PM(0.2987) 0.4945 Total mass(EIm components), kg 5.4353 Power density, kW / kg (2.05835 / 5.4353) 0.3787

[0114] As shown in FIG. 16, the SPMSM (IV) proposed by the present invention has a maximum voltage of 20[V] and a cogging torque of 102.37[mNm], which is 29.7% lower than the conventional SPMSM (I), an iron loss of 91.4[W], and a permanent magnet loss of 14.4[W], etc.

[0115] In addition, the SPMSM(IV) proposed by the present invention has a rated torque of 7.02 Nm, which is 37% higher than the conventional one.

[0117] In addition, as shown in FIG. 17, the proposed SPMSM (V) is of the double-pore type and is as follows.

[0118] In addition, the proposed SPMSM (V) has a pair of 24 slots and 20 poles.

[0119] Here, the material of the above SPMSM(Ⅴ) is 20PN1500.

[0120] SPMSM(Ⅴ) Parameter Value Stator current frequency, Hz 500 Rotor speed, rpm 3,000 Shaft torque, Nm 6.57 Electromagnetic torque, Nm 6.98 Shaft power(output power), W 2066.24 Input electric power, W (2π×(3000 / 60)×6.98)+(50×50×(0.0033+0.0026)×3) 2237.08 Efficiency, % (2066.24 / 2192.83)×100% 94.23 Winding losses, W (50×50×(0.0033+0.0026)×3) 44.25 Core losses, W 67.8 Losses in PMs, W 17.78 Mechanical losses, W 41.01 Stator current, A rms 50 Stator current density, A / mm 2 (50 / 2) / (0.4064×0.4064×3.14)×10×2=9.636 9.636 Mass of Cu, kg Outer_Stator_Cu(0.4421)+Inner_Rotor_Fe(0.2611) 0.7032 Mass of Fe, kg (Outer_Stator_Fe(1.7886)+Outer_Rotor_Fe(0.3051)+Inner_Stator_Fe(1.6047)+Inner_Rotor Fe(0.5392)) 2.0937+2.1439 = 4.2376 Mass of PM, kg Outer_Stator_PM(0.1958)+Inner_Rotor_PM(0.2987) 0.4945 Total mass(EIm components), kg 5.4353 Power density, kW / kg (2.06624 / 5.4353) 0.3801

[0121] As shown in FIG. 18, the SPMSM (V) proposed by the present invention has a maximum voltage of 20.32[V] and a cogging torque of 93.4[mNm], which is 35.9% lower than the conventional SPMSM (I), an iron loss of 67.8[W], and a permanent magnet loss of 17.78[W], etc.

[0122] In addition, the SPMSM (V) proposed by the present invention has a rated torque of 6.98 Nm, which is 36.67% higher than the conventional one.

[0124] 3. 결 론

[0125] In the case of conventional SPMSMs, iron loss, permanent magnet loss, and mechanical loss are low, but the output density and torque are also low.

[0126] On the other hand, in the case of the proposed motor (electric motor), if 35PN380, which is the same material as the conventional SPMSM, is used, iron loss is large and permanent magnet loss increases due to the double stator structure, but high power density is obtained while achieving efficiency similar to the conventional one.

[0127] In addition, when the 20PN1500 was applied to reduce iron loss, the iron loss was reduced, but the loss of the permanent magnet increased; however, when comparing efficiency and power density, the efficiency increased by 2.23% and the power density increased by 22.23% compared to the conventional SPMSM.

[0129] FIG. 19 is an exemplary cross-sectional view illustrating an improved double-air gap type SPMSM according to an embodiment of the present invention, FIG. 20 is an enlarged view of the “Q” portion of FIG. 19, FIG. 21 is an exemplary longitudinal cross-sectional view illustrating an improved double-air gap type SPMSM according to an embodiment of the present invention, and FIG. 22 is a drawing showing the magnetic flux direction to explain an improved double-air gap type SPMSM according to an embodiment of the present invention.

[0130] In addition, FIG. 23 is a diagram showing the winding direction for phase A of three phases, exemplarily, to explain an improved double-air gap type SPMSM according to an embodiment of the present invention, FIG. 24 and FIG. 25 are circuit diagrams to explain an improved double-air gap type SPMSM according to an embodiment of the present invention, and FIG. 26 is an exemplary diagram showing the partition section of an improved double-air gap type SPMSM according to an embodiment of the present invention.

[0131] Meanwhile, in order to make the above drawings easier to understand, there are parts that are exaggerated as shown in Fig. 21.

[0133] Accordingly, based on the above-mentioned experimental results, the present invention is proposed as follows.

[0134] As illustrated in FIG. 19, an improved double-air-type surface permanent magnet synchronous motor (100) according to one embodiment of the present invention includes a first stator (110), a first rotor (120), a first permanent magnet (130), a second rotor (140), a second permanent magnet (150), and a second stator (160), etc.

[0135] As shown in FIG. 19 and FIG. 20, the first stator (110) has a first projection (110p) formed along the first inner surface (110s).

[0136] Here, the first projection (110p) is formed as a 'T'-shaped projection along the first inner surface (110s) at a predetermined interval.

[0137] Additionally, the first rotor (120) has a first outer surface (120s) formed facing the first inner surface (110s).

[0138] Meanwhile, the first rotor (120) is manufactured by stacking multiple silicon steel sheets or is a non-oriented electrical steel sheet produced by a company (POSCO), such as 35PN380, with a thickness of 0.35±0.05mm and a density of 7.65±0.1kg / cm² 2 , core loss 3.80 W / kg or less, magnetic flux density 1.62 or more, packing factor 95% or more, and has standard dimensions, magnetic properties, etc.

[0139] Additionally, the first permanent magnet (130) is arranged in multiple numbers along the first outer surface (120s).

[0140] In particular, the first permanent magnet (130) has N poles (blue) and S poles (red) arranged alternately at equal intervals along the first outer surface (120s).

[0141] Additionally, the second rotor (140) is integrally connected to the first rotor (120) in an inwardly corresponding manner to form a second inner surface (140s).

[0142] Meanwhile, the second rotor (140) is manufactured by stacking multiple silicon steel sheets or is a non-oriented electrical steel sheet produced by a company (POSCO), such as 35PN380, with a thickness of 0.35±0.05mm and a density of 7.65±0.1kg / cm² 2 , core loss 3.80 W / kg or less, magnetic flux density 1.62 or more, packing factor 95% or more, and has standard dimensions, magnetic properties, etc.

[0143] Additionally, a plurality of second permanent magnets (150) are arranged along the second inner surface (140s).

[0144] In particular, the second permanent magnet (150) has N poles (blue) and S poles (red) arranged alternately at equal intervals along the second inner surface (140s), but with opposite polarity to the first permanent magnet (130).

[0145] Additionally, the second permanent magnet (150) is formed in the same number as the first permanent magnet (130), but is smaller than the number of the first protrusion (110p) or the second protrusion (160p).

[0146] In addition, the number of poles proposed by the present invention is the number of first permanent magnets (130) or second permanent magnets (150).

[0147] Additionally, the second stator (160) has a second projection (160p) formed along the second outer surface (160s) facing the second inner surface (140s).

[0148] Here, the second projection (160p) is a 'T'-shaped projection spaced apart at a predetermined interval along the second outer surface (160s).

[0149] In addition, the second protrusion (160p) is formed in the same number as the first protrusion (110p).

[0150] Meanwhile, the present invention is implemented with 24 first protrusions (110p) and 24 second protrusions (160p), 20 first permanent magnets (130), and 20 second permanent magnets (150), and the quantity may be changed as needed.

[0152] As shown in FIG. 20, the first air gap (t01) has a predetermined air gap formed between the first stator (110) and the first rotor (120), with an air gap of 0.8 ± 0.1 mm.

[0153] In addition, the second air gap (t02) has a predetermined air gap formed between the second stator (160) and the second rotor (140), and has an air gap of 0.8 ± 0.1 mm.

[0155] In addition, the first and second rotors (120, 140) according to another embodiment of the present invention are made of electrical steel sheets laminated with a thickness of 0.20 ± 0.05 mm, and are made of a material having a density of 7.65 ± 0.1 kg / cm2, a core loss of 15.0 W / kg or less, a magnetic flux density of 1.62 or more, and a packing density of 93% or more.

[0156] That is, the first and second rotors (120, 140) are non-oriented electrical steel sheets produced by a company (POSCO), such as 20PN1500, with a thickness of 0.20±0.05mm and a density of 7.65±0.1kg / cm³ 2 , core loss (iron loss) 15.0 W / kg or less, magnetic flux density 1.62 or more, packing factor 93% or more, and has standard dimensions, magnetic properties, etc.

[0158] As shown in FIG. 21, the first and second rotors (120, 140) are fixed to a circular plate member (170) on one side and rotate.

[0159] That is, the present invention transmits the force of rotation of the first and second rotors (120, 140) by the current applied from the windings (110w, 160w) of the first and second stators (110, 160) to the circular plate member (170) to cause it to rotate.

[0161] In particular, as shown in FIG. 22, since the partition (180) according to an embodiment of the present invention is formed at the boundary of the first rotor and the second rotor (120, 140), the mutual magnetic flux generated from the first and second permanent magnets (130, 150) is blocked to prevent mutual collision, thereby improving performance such as power density.

[0162] At this time, the partition (180) is formed of a non-magnetic material such as stainless steel to prevent the magnetic flux of the first permanent magnet (130) from encroaching on the second rotor (140) and to prevent the magnetic flux of the second permanent magnet (150) from encroaching on the first rotor (120).

[0164] As illustrated in FIGS. 21 and FIGS. 23 to 25, the present invention further includes first and second control devices (210, 220).

[0165] In addition, the first control device (210) is connected to the first winding (110w), and the second control device (220) is connected to the second winding (160w).

[0166] Here, FIG. 23 schematically illustrates the winding for Phase A of the three phases, and the corresponding circuit diagram is shown in FIG. 24 and FIG. 25. (Since Phases B and C are applied in the same pattern as Phase A, the explanation is omitted.)

[0167] Conventionally, since the entire current flow was controlled by a single control unit, there was a problem where the entire system could not operate if a part of a complexly connected motor was damaged or broken.

[0168] Accordingly, the present invention includes two control devices, wherein the first control device (210) controls the first winding (110w) wound on the first protrusion (110p) and the second control device (220) controls the second winding (160w) wound on the second protrusion (160p), so that even if either of the first and second control devices (210, 220) fails, the other one can control the rotation of the first and second rotors (120, 140) formed as a single unit.

[0170] As illustrated in FIG. 26, the present invention further includes a sleeve portion (190) to solve the conventional problems such as the first permanent magnet (130) on the outer edge easily falling out due to centrifugal force or being damaged by colliding with it during rotation, or the second permanent magnet (150) on the inner edge deviating from the direction of rotation due to centripetal force or being damaged by colliding with the surroundings.

[0171] That is, the sleeve portion (190) proposed by the present invention includes a first sleeve portion (190a) and a second sleeve portion (190b).

[0172] Additionally, the first sleeve portion (190a) is a metal material having a predetermined thickness that has a hollow cylindrical shape with open front and rear ends, and protects the first permanent magnet (130) while preventing it from falling out by wrapping around the outer edge of the first permanent magnet (130), and has a predetermined tensile strength so as to firmly cover the first permanent magnet (130).

[0174] In addition, the second sleeve portion (190b) is a metal material having a predetermined thickness that has a hollow cylindrical shape with open front and rear ends, which surrounds and supports the inner rim of the second permanent magnet (150) to prevent it from falling out and protects the second permanent magnet (150), and has a predetermined tensile strength to firmly cover and support the second permanent magnet (150).

[0176] In summary, an improved double-air-gap surface permanent magnet synchronous motor (100) according to one embodiment of the present invention comprises: a first stator (110) having a first protrusion (110p) in the shape of a 'T' formed along a first inner surface (110s); a first rotor (120) having a first outer surface (120s) formed facing the first inner surface (110s); a first permanent magnet (130) arranged along the first outer surface (120s); a second rotor (140) having a second inner surface (140s) formed integrally connected to the first rotor (120) inwardly and correspondingly; and a second permanent magnet (150) arranged along the second inner surface (140s). and a second stator (160) having a second protrusion (160p) in the shape of a 'T' formed along a second outer surface (160s) formed facing the second inner surface (140s);

[0177] Additionally, a first air gap (t01) of a predetermined space is formed between the first stator (110) and the first rotor (120), and a second air gap (t02) of a predetermined space is formed between the second stator (160) and the second rotor (140).

[0178] Additionally, the first permanent magnet (130) has N and S poles arranged alternately at equal intervals along the first outer surface (120s), and the second permanent magnet (150) has N and S poles arranged alternately at equal intervals along the second inner surface (140s), arranged with opposite polarity to the first permanent magnet (130).

[0179] Additionally, the first protrusion (110p) is formed in the same number as the second protrusion (160p), and the first permanent magnet (130) is formed in the same number as the second permanent magnet (150), but is smaller than the number of the first protrusion (110p).

[0180] Additionally, the first projection (110p) is a 'T'-shaped projection spaced apart at a predetermined interval along the first inner surface (110s), and the second projection (160p) is a 'T'-shaped projection spaced apart at a predetermined interval along the second outer surface (160s).

[0181] In addition, the first protrusions (110p) are 24 in number, and the first permanent magnets (130) are 20 in number.

[0182] In addition, the first and second rotors (120, 140) are made of electrical steel sheets laminated with a thickness of 0.20 ± 0.05 mm, with a density of 7.65 ± 0.1 kg / cm2, a core loss of 15.0 W / kg or less, a magnetic flux density of 1.62 or more, and a packing density of 93% or more.

[0183] In addition, the first and second rotors (120, 140) are fixed to a circular plate member (170) having a rotation axis (170r) formed on one side and rotate.

[0184] In addition, it further includes a partition (180) formed at the boundary between the first rotor and the second rotor (120, 140).

[0185] In addition, the above partition (180) blocks the mutual magnetic flux generated from the first and second permanent magnets (130, 150).

[0186] In addition, the above partition (180) is formed of a non-magnetic material.

[0187] Additionally, the first control device (210) that electrically controls the first winding (110w) wound on the first protrusion (110p); and the second control device (220) that electrically controls the second winding (160w) wound on the second protrusion (160p); are further included so that if either of the first and second control devices (210, 220) fails, the other one controls the rotation of the first and second rotors (120, 140) which are formed as a single unit.

[0188] Additionally, it further includes a first sleeve portion (190a) of a predetermined thickness that wraps around the outer edge of the first permanent magnet (130) in a hollow cylindrical shape with open front and rear ends to prevent it from falling out and to protect it, and a second sleeve portion (190b) of a predetermined thickness that wraps around and supports the inner edge of the second permanent magnet (150) in a hollow cylindrical shape with open front and rear ends to prevent it from falling out and to protect it.

[0189] In addition, the first and second sleeve portions (190a, 190b) are made of metal.

[0191] Accordingly, the improved double-air-gap surface permanent magnet synchronous motor (100) according to one embodiment of the present invention can be expected to have the following effects.

[0192] According to the present invention, since it has a double-hole structure, it has the advantage of having high power density and torque.

[0193] In addition, due to the double-hole structure, there is an advantage of being able to lower the cogging torque compared to conventional methods.

[0194] In addition, there is an advantage of increasing efficiency by improving the material of the double porous structure under the same conditions.

[0195] In addition, since the partition (180) blocks the mutual magnetic flux generated from the first and second permanent magnets, there is an advantage in that high torque can be generated.

[0196] In addition, there is an advantage in having dual control devices so that even if one of them fails, the other can still control it.

[0197] In addition, there is an advantage in that the first and second permanent magnets (130, 150) are prevented from falling out through the cylindrical sleeve portion (190).

[0199] The above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications, changes, and substitutions within the scope of the essential characteristics of the present invention without departing from its nature.

[0200] Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by such embodiments and accompanying drawings.

[0201] The scope of protection of the present invention shall be interpreted by the claims below, and all technical ideas within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention. Explanation of the symbols

[0202] 100 : Motor proposed by the present invention 110: First stator 120: 1st rotor 130: First permanent magnet 140: Second rotor 150 : Second permanent magnet 160 : Second stator 170 : Circular plate member 180: Bulkhead 190: Sleeve part 210: First control device 220 : Second control device

Claims

Claim 1 A first stator having a first 'T'-shaped projection formed along a first inner surface; a first rotor having a first outer surface formed facing the first inner surface; a first permanent magnet arranged along the first outer surface; a second rotor having a second inner surface formed integrally connected to the first rotor inwardly and corresponding to it; and a second permanent magnet arranged along the second inner surface. and a second stator having a second 'T'-shaped projection formed along a second outer surface formed facing the second inner surface; wherein a first air gap of a predetermined space is formed between the first stator and the first rotor, and a second air gap of a predetermined space is formed between the second stator and the second rotor; wherein the first permanent magnet has N poles and S poles alternately arranged at equal intervals along the first outer surface, and the second permanent magnet has N poles and S poles alternately arranged at equal intervals along the second inner surface, arranged with opposite polarity to the first permanent magnet; wherein the first projection is formed in the same number as the second projection, and the first permanent magnet is formed in the same number as the second permanent magnet but is smaller than the number of the first projection; and the first and second rotors are electrical steel sheets laminated with a thickness of 0.20 ± 0.05 mm, with a density of 7.65 ± 0.1 kg / cm³ 2 An improved double-air gap type surface permanent magnet synchronous motor characterized by being made of a material having a core loss of 15.0 W / kg or less, a magnetic flux density of 1.62 or more, and a packing factor of 93% or more. Claim 2 An improved double-air gap type surface permanent magnet synchronous motor according to claim 1, characterized in that the first protrusions are 24 in number and the first permanent magnets are 20 in number. Claim 3 An improved double-air gap type surface permanent magnet synchronous motor according to claim 1, characterized in that the first and second rotors are fixed to a circular plate member having a rotation axis formed on one side and rotate.

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