Electric motor comprising circuit for minimizing shaft voltage

Abstract

This electric motor may comprise: a first capacitance unit of capacitance C1 including a stray capacitance formed by a winding and a metal steel plate; a second capacitance unit of capacitance C2 including a stray capacitance formed by a substrate and a metal steel plate; a third capacitance unit of capacitance C3 including a stray capacitance caused by a rotor and a stator; and a fourth capacitance unit of capacitance C4 including a stray capacitance caused by a substrate and a shaft. According to one embodiment, the electric motor may comprise a capacitance adjustment unit that adjusts a ratio of C1 to C2 to be the same as a ratio of C3 to C4 within a predetermined error.

Description

Motor including a circuit that minimizes shaft voltage

[0001] The present disclosure relates to an electric motor comprising a circuit that minimizes shaft voltage.

[0002] Electric motors are used in a wide variety of home appliances.

[0003] By adding a capacitor (C3) to the motor shaft current suppression mechanism, the three-phase lines of the controller or motor can be grounded, and accordingly, the high-frequency common mode voltage can be divided. As a result, the motor shaft current suppression mechanism can reduce the voltage transmitted to the bearing, thereby suppressing electrolytic corrosion of the bearing.

[0004] On the other hand, in a permanent magnet motor, the capacitance (Cr) on the rotor side may be greater than the capacitance (Cs) on the stator side. By equipping this permanent magnet motor with a conductive sheet, the capacitance of the stator side (Cs) can become closer to the capacitance of the rotor side (Cr) as the capacitance of the stator side (Cs) increases. Consequently, the shaft voltage is reduced, which can suppress the occurrence of electrolytic corrosion in the bearings.

[0005] An electric motor is provided that includes a capacitance adjustment unit for making the capacitor voltage 0V or close to 0V. An electric motor according to one embodiment of the present disclosure may include a rotor including a magnet, a stator including a winding, a shaft rotating together with the rotor, a bearing disposed on the shaft, a metal plate supporting the bearing, and a substrate outputting a driving signal to the winding. According to one embodiment, the electric motor may include a first capacitance part of capacitance C1 including a floating capacitance formed by the winding and the metal plate. According to one embodiment, the electric motor may include a second capacitance part of capacitance C2 including a floating capacitance formed by the substrate and the metal plate. According to one embodiment, it may include a third capacitance part of capacitance C3 including a floating capacitance attributable to the rotor and the stator. According to one embodiment, it may include a fourth capacitance part of capacitance C4 including a floating capacitance attributable to the substrate and the shaft. According to one embodiment, the electric motor may include a capacitance adjustment unit that adjusts the ratio of C1 to C2 to be equal to the ratio of C3 to C4 within a predetermined error.

[0006] FIG. 1 is a cross-sectional view showing an example of the configuration of an electric motor according to one embodiment of the present disclosure.

[0007] FIG. 2 is an equivalent circuit diagram regarding the capacitance of an electric motor according to one embodiment of the present disclosure.

[0008] FIG. 3 is a cross-sectional view showing an example of the configuration of an electric motor according to one embodiment of the present disclosure.

[0009] FIG. 4 is an equivalent circuit diagram regarding the capacitance of a motor according to one embodiment of the present disclosure.

[0010] FIG. 5 is a drawing showing a specific connection example of an adjustment capacitor according to one embodiment of the present disclosure.

[0011] FIG. 6 is a graph showing that the capacitor voltage can be adjusted to 0V by changing the capacitance of the adjustment capacitor according to one embodiment of the present disclosure.

[0012] FIG. 7a is a graph showing the common mode voltage and shaft voltage at point (P1) in FIG. 6 according to one embodiment of the present disclosure.

[0013] FIG. 7b is a graph showing the common mode voltage and shaft voltage at point (P2) of FIG. 6 according to one embodiment of the present disclosure.

[0014] FIG. 7c is a graph showing the common mode voltage and shaft voltage at point (P3) of FIG. 6 according to one embodiment of the present disclosure.

[0015] FIG. 7d is a graph showing the common mode voltage and shaft voltage at point (P4) of FIG. 6 according to one embodiment of the present disclosure.

[0016] FIG. 8 is a cross-sectional view showing an example of the configuration of an electric motor according to one embodiment of the present disclosure.

[0017] FIG. 9 is an equivalent circuit diagram regarding the capacitance of a motor according to one embodiment of the present disclosure.

[0018] FIG. 10 is a drawing showing a specific connection example of an adjustment capacitor according to one embodiment of the present disclosure.

[0019] FIG. 11 is a cross-sectional view showing an example of the configuration of an electric motor according to one embodiment of the present disclosure.

[0020] FIG. 12 is an equivalent circuit regarding capacitance according to one embodiment of the present disclosure.

[0021] FIG. 13 is an air conditioner according to one embodiment of the present disclosure.

[0022] The embodiments of the present disclosure and the terms used therein are not intended to limit the technical features described in this document to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of said embodiments.

[0023] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0024] The singular form of a noun may include either one or both, unless the relevant context clearly indicates otherwise.

[0025] Unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" may be understood to include plural objects. Thus, for example, the description "constituent surface" may include cases where it refers to one or more of such surfaces.

[0026] In this document, each of the phrases such as "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C", and "at least one of A, B, or C" may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0027] The term “and / or” includes a combination of multiple related described components or any of the multiple related described components.

[0028] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish a component from another component and do not limit the components in other aspects (e.g., importance or order).

[0029] Where any (e.g., 1st) component is referred to as "coupled" or "connected" to another (e.g., 2nd) component, with or without the terms "functionally" or "communicationly," it means that said any component may be connected to said other component directly (e.g., via a wire), wirelessly, or through a third component.

[0030] Terms such as “include” or “have” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this document, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0031] When it is said that one component is “connected,” “combined,” “supported,” or “in contact” with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0032] When it is said that a component is located “on” another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0033] It should be understood that the blocks in each flowchart and combinations of flowcharts can be executed by one or more computer programs containing computer-executable instructions. One or more computer programs may be stored all in a single memory or may be partitioned and stored in multiple different memories.

[0034] All functions or operations described in this disclosure may be processed by a single processor or a combination of processors. A single processor or a combination of processors is a circuitry that performs processing and may include a circuitry such as an application processor (AP), a communication processor (CP), a graphical processing unit (GPU), a neural processing unit (NPU), a microprocessor unit (MPU), a system on chip (SoC), or an integrated chip (IC).

[0035] The processor of the present disclosure may generate control signals for controlling the operation of an electronic device based on instructions, applications, data, and / or programs stored in memory. The processor may include logic circuits and arithmetic circuits as hardware. The processor may process data according to programs and / or instructions provided from memory and generate control signals according to the processing results. The memory and the processor may be implemented as a single control circuit or as a plurality of circuits.

[0036] A processor may include various processing circuits and / or multiple processors. For example, the term “processor” as used herein, including in the claims, may include at least one processor and various processing circuits. In at least one processor, one or more processors may be configured to perform the various functions described herein in a distributed manner, individually and / or collectively. As used herein, “processor,” “at least one processor,” and “one or more processors” may be configured to perform various functions. However, these terms include, without limitation, situations where one processor performs some of the functions and other processor(s) perform other parts of the functions, and situations where a single processor can perform all functions. Additionally, at least one processor may include a combination of processors performing various functions of the disclosed functions in a distributed manner. At least one processor may execute program instructions to achieve or perform various functions. In this disclosure, “processor” may include “at least one processor” or “one or more processors.”

[0037] In the present disclosure, the processor may write data to memory or read data stored in memory, and in particular, process data according to a predefined operation rule or artificial intelligence model by executing a program or at least one instruction stored in memory. Accordingly, the processor may perform operations described in subsequent embodiments, and operations described in subsequent embodiments as being performed by an electronic device or a detailed component included in an electronic device may be considered to be performed by the processor unless otherwise specified.

[0038] In the present disclosure, functions related to 'artificial intelligence' are operated through a processor and memory. The processor may be composed of one or more processors. In this case, the one or more processors may be a general-purpose processor such as a CPU, AP, or DSP (digital signal processor), a graphics-dedicated processor such as a GPU or VPU (vision processing unit), or an AI-dedicated processor such as an NPU. The one or more processors control the processing of input data according to predefined operation rules or AI models stored in memory. Alternatively, if the one or more processors are AI-dedicated processors, the AI-dedicated processors may be designed with a hardware structure specialized for processing a specific AI model.

[0039] The predefined rules of operation or artificial intelligence models are characterized by being created through learning. Here, being created through learning means that a predefined rules of operation or artificial intelligence models configured to perform desired characteristics (or objectives) are created by a basic artificial intelligence model being trained using multiple learning data by a learning algorithm. Such learning may be performed on the device itself where the artificial intelligence according to the present disclosure is executed, or it may be performed through a separate server and / or system. Examples of learning algorithms include supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning, but are not limited to the examples described above.

[0040] In the present disclosure, an "artificial intelligence model" may be a model that analyzes linear or non-linear correlations between a plurality of operands (which may also be referred to as variables or parameters). For example, the artificial intelligence model may include at least one of linear regression, polynomial regression, logistic regression, decision trees, support vector machines (SVM), and linear correlation neural networks, but the present disclosure is not limited thereto. In one embodiment of the present disclosure, the artificial intelligence model may infer another type of variable by taking one type of variable as input. In one embodiment of the present disclosure, the artificial intelligence model may infer a correlation coefficient between variables by taking other types of variables as input. For example, correlation coefficients may include Pearson correlation coefficients, Spearman correlation coefficients, Kendall's tau, or point-biserial correlation coefficients, but the present disclosure is not limited thereto.

[0041] In one embodiment of the present disclosure, the 'artificial intelligence model' may include a neural network model. The neural network model may be composed of a plurality of neural network layers. Each of the plurality of neural network layers has a plurality of weight values ​​and performs neural network operations through operations between the operation result of a previous layer and the plurality of weights. The plurality of weights possessed by the plurality of neural network layers may be optimized by the learning result of the artificial intelligence model. For example, the plurality of weights may be updated so that the loss value or cost value obtained from the artificial intelligence model during the learning process is reduced or minimized. The artificial neural network model may include a deep neural network (DNN), and examples include a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted Boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), or deep Q-networks, but is not limited to the examples described above.

[0042] In the present disclosure, the term “user” means a person who controls a system, function, or operation, and may include a developer, administrator, installer, or repair technician.

[0043] Hereinafter, an electric motor according to one embodiment of the present disclosure is described with reference to the attached drawings.

[0044] For example, according to one embodiment of the present disclosure, the shaft voltage can be reduced by providing an insulating layer on the rotor core of the motor. However, in this method, fine adjustment or verification of the effect cannot be performed after the motor is completed. In the present disclosure, a method for reducing the shaft voltage while enabling fine adjustment or verification of the effect after the motor is completed will be provided. FIG. 1 is a cross-sectional view showing an example of the configuration of a motor (5) according to one embodiment of the present disclosure.

[0045] As illustrated in FIG. 1, an electric motor (5) according to one embodiment of the present disclosure may include a rotor (10), a stator (20), and a shaft (30). According to one embodiment, the electric motor (5) may further include a first bearing (41), a second bearing (42), a first metal plate (51), a second metal plate (52), a substrate (60), and a casing (70). Hereinafter, an Interior Permanent Magnet (IPM) motor in which magnets (12) are radially embedded in the rotor (10) is described as an example of the electric motor (5), but the electric motor according to one embodiment of the present disclosure is not limited thereto.

[0046] The rotor (10) may be positioned inside the stator (20) with an air gap between it and the stator (20). The rotor (10) rotates in the electric motor (5) and may include a rotor core (11) and a magnet (12). The rotor core (11) has an annular hub portion (111) on the inner side in the radial direction and a plurality of radial spoke portions (112) on the outer side in the radial direction. A plurality of magnets (12) may exist. Each of the plurality of magnets (12) may be positioned radially between adjacent spoke portions (112) and facing the stator (20). Additionally, FIG. 1 is a cross-sectional view of the electric motor (5) cut along a cutting plane extending outward in the radial direction from the shaft (30) through the center of the spoke portion (112), so the magnet (12) does not exist on this cutting plane. However, in Fig. 1, the magnet (12) is also illustrated for convenience.

[0047] The stator (20) can generate a rotating magnetic field and rotate the rotor (10) by the rotating magnetic field. The stator (20) may include a stator core (21) and a winding (22). The winding (22) may be wound around the stator (20) through an insulator (23) to insulate the stator core (21). The stator (20) may be molded in resin together with other fixed members. According to one embodiment of the present disclosure, the fixed members may be molded integrally so that the stator (20) having an external shape of approximately cylindrical shape may be formed.

[0048] The shaft (30) is fixed to the rotor (10) and can rotate together with the rotor (10). The shaft (30) can rotate by being supported by the first bearing (41) and the second bearing (42). The shaft (30) can protrude from the first metal plate (51).

[0049] The first bearing (41) may be positioned at the top of the shaft (30) to support the shaft (30). The first bearing (41) may include a cylindrical bearing having a plurality of balls (411). The inner ring (412) of the first bearing (41) may be fixed to the shaft (30) and electrically conductive. The outer ring (413) side of the first bearing (41) may be fixed to the first metal plate (51) and electrically conductive.

[0050] The second bearing (42) is positioned at the bottom of the shaft (30) to support the shaft (30). The second bearing (42) may include a cylindrical bearing having a plurality of balls (421). The inner ring (422) side of the second bearing (42) is fixed to the shaft (30) and can be electrically conductive. The outer ring (423) side of the second bearing (42) is fixed to the second metal plate (52) and can be electrically conductive.

[0051] The first bearing (41) and the second bearing (42) are examples of bearings.

[0052] The first metal plate (51) may include a conductive member positioned at the top of the motor (5). The first metal plate (51) may support a first bearing (41) positioned in its center.

[0053] The second metal plate (52) may include a conductive member disposed at the bottom of the motor (5). The second metal plate (52) may support a second bearing (42) disposed in its center.

[0054] The outer diameter of the second metal plate (52) may be the same as or larger than the outer diameter of the first metal plate (51). Accordingly, the first bearing (41) and the second bearing (42) are stably supported so that the shaft (30) can rotate.

[0055] The first metal steel plate (51) and the second metal steel plate (52) are examples of metal steel plates.

[0056] The substrate (60) may be placed inside the motor (5), and a driving circuit (not shown) that outputs a driving signal to generate a rotating magnetic field in the winding (22) may be mounted thereon. The substrate (60) may be placed between the rotor (10) and the stator (20) and the second metal plate (52). For example, the driving circuit may include an inverter circuit for applying voltage to the winding (22). Additionally, the substrate (60) may be connected to a ground (GND) that serves as a reference point for the circuit.

[0057] The casing (70) may include at least a rotor (10), a stator (20), a first bearing (41), and a second bearing (42). According to one embodiment, the casing (70) may further include a substrate (60). The casing (70) may include a first metal sheet (51) and a second metal sheet (52).

[0058] For the motor (5) configured as described above, by applying voltage to the winding (22) in the driving circuit, current flows through the winding (22), and a magnetic field can be generated from the stator core (21). Then, due to the rotating magnetic field from the stator core (21) and the magnetic field from the magnet (12), an attractive force and a repulsive force can be generated according to the polarity of these magnetic fields. Due to these forces, the rotor (10) can rotate around the shaft (30).

[0059] FIG. 2 is an equivalent circuit diagram regarding the capacitance of a motor (5) according to one embodiment of the present disclosure.

[0060] As shown in FIG. 2, a common mode voltage (Vcom), which is the potential difference between the reference point (GND) of the substrate (60) and the neutral point (NP) of the winding (22), is applied to the winding (22) by the substrate (60).

[0061] In addition, as shown in FIGS. 1 and 2, a first capacitance (Cr, 101) exists between the winding (22) and the second metal sheet (52).

[0062] A second capacitance (Cn, 102) exists between the reference point (GND) of the substrate (60) and the second metal steel plate (52).

[0063] A third capacitance (Cs, 103) exists in the insulator (23) between the winding (22) and the stator core (21), and a fourth capacitance (Cg, 104) exists in the air gap between the stator core (21) and the rotor core (11). A fifth capacitance (Cm, 105) exists between the winding (22) and the magnet (12). A sixth capacitance (Cmg, 106) exists within the magnet (12).

[0064] A seventh capacitance (Csn, 107) exists between the reference point (GND) of the substrate (60) and the shaft (30).

[0065] There is an eighth capacitance (Cb1, 108) between the inner ring (412) and the outer ring (413) of the first bearing (41).

[0066] A ninth capacitance (Cb2, 109) exists between the inner ring (422) and the outer ring (423) of the second bearing (42).

[0067] However, a PWM (Pulse Width Modulation) inverter can be employed in this motor (5).

[0068] However, in a PWM type inverter, a common mode voltage is generated by switching, and this common mode voltage can be divided according to the capacitance within the motor (5). Accordingly, a potential difference called the shaft voltage can be generated between the inner ring (412) and the outer ring (413) of the first bearing (41) and between the inner ring (422) and the outer ring (423) of the second bearing (42). Since the shaft voltage is desirable to be small because if it exceeds the dielectric breakdown voltage of the bearing grease film, it leads to the occurrence of electrolytic corrosion that causes damage to the surfaces within the first bearing (41) and the second bearing (42).

[0069] According to one embodiment of the present disclosure, by adjusting the ratio in which the common mode voltage is divided within the motor (5), the shaft voltage is brought close to 0V to suppress the occurrence of electrolytic corrosion. According to one embodiment of the present disclosure, the shaft voltage coming close to 0V may include the shaft voltage becoming completely 0V or nearly 0V within a predetermined value. The predetermined value may vary depending on the magnitude of the common mode voltage of the motor (5), but for example, it may be a value within 10V. Preferably, the predetermined value may be a value within 5V.

[0070] Here, the following methods exist to suppress the occurrence of electrolytic corrosion. First, there is a method to improve the dielectric breakdown strength of the first bearing (41) and the second bearing (42). Second, there is a method to reduce the shaft voltage. A major example of the former method is to change the balls (411) of the first bearing (41) and the balls (421) of the second bearing (42) to ceramic. However, this method significantly increases material costs. On the other hand, an example of the latter method is to provide an insulating layer on the rotor core (11). However, this method has problems such as the insulating layer not being fine-tunable once the mold is made, and the effect of the insulating layer on the shaft voltage being confirmed only after the motor (5) is completed.

[0071] In order to reduce shaft voltage according to one embodiment of the present disclosure, with respect to the first bearing (41), the magnitude of the voltage divided between the inner ring (412) and the outer ring (413) respectively must be equal. According to one embodiment, with respect to the second bearing (42), the magnitude of the voltage divided between the inner ring (422) and the outer ring (423) respectively must be equal. In other words, the magnitude of the voltage divided between the shaft (30) and the second metal plate (52) respectively must be equal.

[0072] To achieve this, it is necessary to secure the following capacitance relationship. In other words, the capacitance of the first capacitance section (81) between the winding (22) and the second metal plate (52) is set to C1. The capacitance of the second capacitance section (82) between the reference point (GND) of the substrate (60) and the second metal plate (52) is set to C2. The capacitance of the third capacitance section (83) between the winding (22) and the shaft (30), that is, between the rotor (10) and the stator (20), is set to C3. The capacitance of the fourth capacitance section (84) between the reference point (GND) of the substrate (60) and the shaft (30) is set to C4. In this case, a relationship can be secured in which the ratio of the capacitance (C1) and the capacitance (C2) matches the ratio of the capacitance (C3) and the capacitance (C4). In other words, a relationship of C1:C2=C3:C4 can be secured.

[0073] However, since the capacitance (C3) is affected by the thickness of the magnet (12) or insulator (23), the air gap, etc., it cannot be adjusted without changing the performance of the motor (5).

[0074] Therefore, according to one embodiment of the present disclosure, a capacitance adjustment unit is added to adjust at least one of the capacitances (C1, C2, and C4), thereby ensuring the relationship C1:C2=C3:C4. Accordingly, after the motor (5) is completed, the size of the capacitance other than the one to be adjusted is measured, and the size of the capacitance (Cadj) of the adjustment capacitor can be determined to match that size. Therefore, the shaft voltage can be reduced while maintaining the characteristics of the motor (5). Here, the adjustment capacitor may be a fixed capacitance capacitor or a variable capacitance capacitor. The capacitance adjustment unit may include an adjustment capacitor or may include a metal member.

[0075] Also, the first capacitance part (81) is an example of a first capacitance part including floating capacitance attributable to the winding and the metal steel plate. The second capacitance part (82) is an example of a second capacitance part including floating capacitance attributable to the substrate and the metal steel plate. The third capacitance part (83) is an example of a third capacitance part including floating capacitance attributable to the rotor and the stator. The fourth capacitance part (84) is an example of a fourth capacitance part including floating capacitance attributable to the substrate and the shaft.

[0076] According to one embodiment of the present disclosure, the capacitance adjustment unit is an example of a capacitor that adjusts the ratio of C1 to C2 to match the ratio of C3 to C4. According to one embodiment, the capacitance adjustment unit may include an adjustment capacitor.

[0077] FIG. 3 is a cross-sectional view showing an example of the configuration of an electric motor (1) according to one embodiment of the present disclosure.

[0078] As shown in FIG. 3, the motor (1) may include an adjustment capacitor (91) disposed between the winding (22) and the second metal plate (52) in FIG. 1.

[0079] FIG. 4 is an equivalent circuit diagram regarding the capacitance of a motor (1) according to one embodiment of the present disclosure.

[0080] As illustrated in FIG. 4, the motor (1) has an adjustment capacitor (91) placed in the first capacitance section (81) of FIG. 2. According to one embodiment, the adjustment capacitor (91) may be connected in parallel with the first capacitance (Cr) between the winding (22) and the second metal plate (52) in the first capacitance section (81). The first capacitance (Cr) may be a stray capacitance.

[0081] FIG. 5 is a drawing showing a specific connection example of an adjustment capacitor (91) included in a capacitance adjustment unit according to one embodiment of the present disclosure.

[0082] As illustrated in FIG. 5, the first terminal of the adjustment capacitor (91) can be connected to the neutral point (NP) of the winding (22). The second terminal of the adjustment capacitor (91) can be connected to the second metal plate (52). Specifically, the second terminal of the adjustment capacitor (91) can be connected to a screw (hole) that fixes the second metal plate (52) on the substrate (60) (see FIG. 3), and can be conductive with the second metal plate (52) through the screw.

[0083] Additionally, the capacitance (Cadj) of the adjustment capacitor (91) can be calculated from the capacitances (C2, C3, C4) after the motor (1) is completed. For example, the capacitance (Cadj) of the adjustment capacitor (91) can be several pF to several tens of pF, but is not limited thereto. However, the capacitance (Cadj) of the adjustment capacitor (91) needs to be set to be less than or equal to the output capacity of the inverter. In other words, if the capacitance (Cadj) of the adjustment capacitor (91) is too large, there is a concern that the switching loss of the inverter may increase, so it needs to be adjusted so that the capacitance (Cadj) of the adjustment capacitor (91) does not become too large—for example, so that it does not become too large to a few mF.

[0084] According to one embodiment of the present disclosure, an adjustment capacitor (91) can be added between the neutral point (NP) of the winding (22) and the second metal plate (52) to adjust the capacitance (C1). Accordingly, by simply mounting the adjustment capacitor (91) on the substrate (60), the relationship C1:C2=C3:C4 can be achieved, and the capacitance voltage can be reduced. According to one embodiment, the ratio of C1 to C2 and the ratio of C3 to C4 may be the same within a predetermined error. At this time, the predetermined error may be within 5%, and more preferably within 1%.

[0085] In this way, the capacitance (Cadj) of the adjustment capacitor (91) is changed, so that the shaft voltage can be adjusted to 0V.

[0086] FIG. 6 is a graph showing that the capacitor voltage can be adjusted to 0V by changing the capacitance of the adjustment capacitor according to one embodiment of the present disclosure.

[0087] FIG. 7a is a graph showing the common mode voltage and shaft voltage at point (P1) in FIG. 6 according to one embodiment of the present disclosure.

[0088] FIG. 7b is a graph showing the common mode voltage and shaft voltage at point (P2) of FIG. 6 according to one embodiment of the present disclosure.

[0089] FIG. 7c is a graph showing the common mode voltage and shaft voltage at point (P3) of FIG. 6 according to one embodiment of the present disclosure.

[0090] FIG. 7d is a graph showing the common mode voltage and shaft voltage at point (P4) of FIG. 6 according to one embodiment of the present disclosure.

[0091] In FIGS. 7a to 7d, the common mode voltage is shown as a dotted line and the shaft voltage as a solid line.

[0092] In addition, here, the capacitance (C2) of the second capacitance part (82) is set to 8.6 pF, the capacitance (C3) of the third capacitance part (83) is set to 74 pF, and the capacitance (C4) of the fourth capacitance part (84) is set to 16.4 pF. Furthermore, by increasing the capacitance (Cadj) of the adjustment capacitor (91) from 0 pF, the capacitance (C1) of the first capacitance part (81) can be increased from 6.65 pF. Moreover, the shaft voltage can be the voltage of the shaft (30) based on the second metal plate (52).

[0093] First, the case where the capacitance (Cadj) of the adjustment capacitor (91) is 0pF, as at point (P1), is considered. In this case, the capacitance (C1) of the first capacitance part (81) becomes 6.65pF, so C1XC4 becomes approximately 109. Meanwhile, C2XC3 is approximately 636. Therefore, C1XC4 < C2XC3 holds true. In other words, since C1 / C2 becomes smaller than C3 / C4, the potential of the shaft (30) becomes higher than that of the second metal plate (52). Therefore, the shaft voltage in FIG. 7a is positive. Also, since it can be seen from FIG. 7a that the shaft voltage is 6V, the shaft voltage for point (P1) in FIG. 6 becomes 6V.

[0094] Next, consider the case where the capacitance (Cadj) of the adjustment capacitor (91) is 21.9 pF, as shown at point (P2). In this case, the capacitance (C1) of the first capacitance part (81) becomes 28.55 pF, so C1 ≠ C4 is approximately 468. Meanwhile, C2 ≠ C3 is approximately 636. Therefore, C1 ≠ C4 < C2 ≠ C3 holds true. In other words, since C1 / C2 becomes smaller than C3 / C4, the potential of the shaft (30) becomes higher than that of the second metal plate (52). Therefore, the shaft voltage in FIG. 7b becomes positive. Also, since it can be seen from FIG. 7b that the shaft voltage is 2V, the shaft voltage for point (P2) in FIG. 6 becomes 2V.

[0095] Next, as shown at point (P3), the case where the capacitance (Cadj) of the adjustment capacitor (91) is 66 pF is given as an example. In this case, the capacitance (C1) of the first capacitance part (81) becomes 72.65 pF, so C1 ≠ C4 is approximately 1191. Meanwhile, C2 ≠ C3 is approximately 636. Therefore, C1 ≠ C4 > C2 ≠ C3 holds true. In other words, since C1 / C2 is greater than C3 / C4, the potential of the second metal plate (52) becomes higher than that of the shaft (30). Therefore, the shaft voltage in FIG. 7c becomes negative. Also, since it can be seen from FIG. 7c that the shaft voltage is -4V, the shaft voltage for point (P3) in FIG. 6 is -4V.

[0096] Next, consider the case where the capacitance (Cadj) of the adjustment capacitor (91) is 141 pF, as shown at point (P4). In this case, the capacitance (C1) of the first capacitance part (81) becomes 147.65 pF, so C1 ≠ C4 is approximately 2421. Meanwhile, C2 ≠ C3 is approximately 636. Therefore, C1 ≠ C4 > C2 ≠ C3 holds true. In other words, since C1 / C2 is greater than C3 / C4, the potential of the second metal plate (52) becomes higher than that of the shaft (30). Therefore, the shaft voltage in FIG. 7d becomes negative. Also, since it can be seen from FIG. 7d that the shaft voltage is -8V, the shaft voltage for point (P4) in FIG. 6 is -8V.

[0097] Also, the waveform of the shaft voltage at point (P4) shown in FIG. 7d is broken. In contrast, the waveform of the shaft voltage at points (P1) to (P3) shown in FIG. 7a to 7c is not broken. This is because at points (P1) to (P3), C1 / XC4 and C2 / XC3 are at values ​​that are somewhat close.

[0098] FIG. 8 is a cross-sectional view showing an example of the configuration of an electric motor according to one embodiment of the present disclosure.

[0099] As shown in FIG. 8, the motor (2) has an adjustment capacitor (92) placed between the substrate (60) and the second metal plate (52) in FIG. 1.

[0100] FIG. 9 is an equivalent circuit diagram regarding the capacitance of a motor according to one embodiment of the present disclosure.

[0101] As shown in FIG. 9, the motor (1) has an adjustment capacitor (92) placed in the second capacitance section (82) in FIG. 2. At this time, the adjustment capacitor (92) can be connected in parallel with the second capacitance (Cn) between the substrate (60) and the second metal plate (52) in the second capacitance section (82).

[0102] FIG. 10 is a drawing showing a specific connection example of an adjustment capacitor (92) according to one embodiment of the present disclosure.

[0103] As illustrated in FIG. 10, the first terminal of the adjustment capacitor (92) can be connected to the potential supply point (Vcc) and reference point (GND) of the substrate (60). The second terminal of the adjustment capacitor (92) can be connected to the second metal plate (52). Specifically, the second terminal of the adjustment capacitor (92) is connected to a screw hole that fixes the second metal plate (52) on the substrate (60), and can be electrically connected to the second metal plate (52) through the screw.

[0104] Additionally, the capacitance (Cadj) of the adjustment capacitor (92) can be set from the capacitances (C1, C3, C4) determined after the motor (2) is completed. For example, the capacitance (Cadj) of the adjustment capacitor (92) may have a value of several pF to several tens of pF, but is not limited thereto. However, the capacitance (Cadj) of the adjustment capacitor (92) needs to be set to be less than or equal to the output capacity of the inverter.

[0105] According to one embodiment of the present disclosure, an adjustment capacitor (92) is added between the potential supply point (Vcc) and reference point (GND) of the substrate (60) and the second metal plate (52) so that the capacitance (C2) can be adjusted. Accordingly, the relationship C1:C2=C3:C4 can be secured simply by mounting the adjustment capacitor (92) on the substrate (60), and the capacitance voltage can be reduced.

[0106] FIG. 11 is a cross-sectional view showing an example of the configuration of an electric motor (3) according to one embodiment of the present disclosure.

[0107] As illustrated in FIG. 11, the electric motor (3) may include a metal member (93) between the substrate (60) and the shaft (30) in FIG. 1. Here, the metal member (93) may be installed on the substrate (60) so as to face the shaft (30). Additionally, the metal member (93) may have any shape, but for example, it may have a ring shape that surrounds the shaft (30).

[0108] FIG. 12 is an equivalent circuit regarding capacitance according to one embodiment of the present disclosure.

[0109] An equivalent circuit regarding the capacitance of a motor (3) according to one embodiment of the present disclosure, including a metal member (83) according to FIG. 11, is illustrated in FIG. 12. According to FIG. 12, a fourth capacitance portion (84) may include a metal member (93). In this case, the metal member (93) may be connected in parallel with a seventh capacitance (Csn) between a substrate (60) and a shaft (30) in the fourth capacitance portion (84).

[0110] According to one embodiment of the present disclosure, a metal member (93) may be added between the substrate (60) and the shaft (30) to adjust the capacitance (C4). Accordingly, by adjusting the capacitance (C1, C2), the relationship C1:C2=C3:C4 can be secured, and the shaft voltage can be reduced. In one embodiment according to FIG. 11, the capacitance adjustment unit for adjusting the ratio of capacitance may include the aforementioned metal member (93).

[0111] Up until now, the substrate (60) has been housed inside the casing (70). However, according to one embodiment, the substrate (60) may be placed outside the casing (70).

[0112] In this case, the capacitance (C2) of the second capacitance part (82) becomes very small as the distance between the reference point (GND) of the substrate (60) and the second metal plate (52) increases, but it does not become zero.

[0113] In addition, the capacitance (C4) of the fourth capacitance part (84) also becomes very small as the distance between the reference point (GND) of the substrate (60) and the shaft (30) increases, but it does not become zero.

[0114] Therefore, in this case as well, the relationship C1:C2=C3:C4 can be established.

[0115] FIG. 13 is an air conditioner according to one embodiment of the present disclosure.

[0116] According to one embodiment of the present disclosure, the air conditioner (1000) may include an outdoor unit (300) and an indoor unit (200). The outdoor unit (300) may include a fan rotated by an electric motor (3) according to one embodiment of the present disclosure.

[0117] When the fan of the outdoor unit (300) is rotated by the motor (3), the shaft voltage can be minimized by capacitance adjustment according to one embodiment of the present disclosure.

[0118] The electric motor (3) according to one embodiment of the present disclosure is not limited to the use of rotating the fan of the outdoor unit (3) of the air conditioner (1000). It can be used in all devices where an electric motor is used—for example, washing machines, dryers, dishwashers, electric ovens, refrigerators, vacuum cleaners, garment care systems, chillers, etc.

[0119] An electric motor is provided that includes a capacitance adjustment unit for making the capacitor voltage 0V or close to 0V. An electric motor according to one embodiment of the present disclosure may include a rotor including a magnet, a stator including a winding, a shaft rotating together with the rotor, a bearing disposed on the shaft, a metal plate supporting the bearing, and a substrate outputting a driving signal to the winding. According to one embodiment, the electric motor may include a first capacitance part of capacitance C1 including a floating capacitance formed by the winding and the metal plate. According to one embodiment, the electric motor may include a second capacitance part of capacitance C2 including a floating capacitance formed by the substrate and the metal plate. According to one embodiment, it may include a third capacitance part of capacitance C3 including a floating capacitance attributable to the rotor and the stator. According to one embodiment, it may include a fourth capacitance part of capacitance C4 including a floating capacitance attributable to the substrate and the shaft. According to one embodiment, the electric motor may include a capacitance adjustment unit that adjusts the ratio of C1 to C2 to be equal to the ratio of C3 to C4 within a predetermined error.

[0120] A capacitance adjustment unit according to one embodiment of the present disclosure may include an adjustment capacitor arranged in parallel with a first capacitance unit.

[0121] A capacitance adjustment unit according to one embodiment of the present disclosure may be connected in parallel with a floating capacitance formed by a winding and a metal plate in a first capacitance unit.

[0122] According to one embodiment of the present disclosure, the bearing may include a first bearing disposed at the upper end of the shaft and a second bearing disposed at the lower end of the shaft. According to one embodiment, the metal plate may include a first metal plate fixed to the outer ring side of the first bearing and a second metal plate fixed to the outer ring side of the second bearing. According to one embodiment, a first end of the capacitance adjustment unit may be connected to the neutral point of the winding and a second end may be connected to the second metal plate.

[0123] According to one embodiment of the present disclosure, the second stage of the capacitance adjustment unit may be connected to a screw hole that fixes the second metal plate and may be electrically connected to the second metal plate.

[0124] According to one embodiment of the present disclosure, the capacitance adjustment unit may include an adjustment capacitor disposed in a second capacitance unit.

[0125] A capacitance adjustment unit according to one embodiment of the present disclosure may be connected in parallel with the floating capacitance formed by the substrate and the metal plate in the second capacitance unit.

[0126] According to one embodiment of the present disclosure, a first stage of the capacitance adjustment unit may be connected to the ground of a substrate, and a second stage of the capacitance adjustment unit may be connected to a second metal plate.

[0127] According to one embodiment of the present disclosure, the capacitance adjustment unit may include a first adjustment capacitor and a second adjustment capacitor. According to one embodiment, a first terminal of the first adjustment capacitor may be connected to a potential supply point of a substrate. According to one embodiment, a first terminal of the second adjustment capacitor may be connected to the ground of the substrate. According to one embodiment, a second terminal of the first adjustment capacitor and a second terminal of the second adjustment capacitor may be connected to a second metal plate.

[0128] A capacitance adjustment unit according to one embodiment of the present disclosure may be disposed in a fourth capacitance unit.

[0129] An electric motor according to one embodiment of the present disclosure may further include a casing. According to one embodiment, the casing may include a rotor, a stator, a bearing, and a substrate. A capacitance adjustment unit according to one embodiment of the present disclosure may include a metal member installed between the substrate and the shaft in a fourth capacitance unit.

[0130] A metal member according to one embodiment of the present disclosure may be in the shape of a ring surrounding a shaft.

[0131] A capacitance adjustment unit according to one embodiment of the present disclosure may be connected in parallel with a floating capacitance formed between a substrate and a shaft.

[0132] According to one embodiment of the present disclosure, the ratio of the common mode voltage in the motor can be adjusted such that the ratio of C1 to C2 is equal to the ratio of C3 to C4 within a predetermined error.

[0133] According to one embodiment of the present disclosure, the capacitance of the adjustment capacitor may be less than or equal to the output capacity of the inverter.

[0134] According to one embodiment of the present disclosure, the electric motor may be included in any one of a washing machine, a dryer, a dishwasher, an electric oven, a refrigerator, a vacuum cleaner, a garment care machine, or a chiller.

[0135] A computer-readable recording medium is disclosed having a program stored therein for performing a method according to one embodiment of the present disclosure on a computer. The computer-readable storage medium may be provided in the form of a non-transitory storage medium. Here, "non-transitory storage medium" simply means that it is a tangible device and does not contain a signal (e.g., electromagnetic waves), and this term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily in the storage medium. For example, the "non-transitory storage medium" may include a buffer in which data is stored temporarily.

[0136] According to one embodiment, the method according to one embodiment of the present disclosure may be provided by being included in a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., downloadable app) may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

Claims

1. A rotor including a magnet; A stator including windings; A shaft that rotates together with the rotor above; A bearing disposed on the shaft above; A metal plate supporting the above bearing; A substrate that outputs a driving signal to the above winding; A first capacitance portion of capacitance C1 including stray capacitance formed by the above winding and the metal steel plate, A second capacitance portion of capacitance C2 including stray capacitance formed by the above substrate and the metal steel plate, A third capacitance part of capacitance C3 including floating capacitance attributable to the rotor and the stator, A fourth capacitance portion of capacitance C4 comprising a floating capacitance attributable to the substrate and the shaft; and An electric motor comprising a capacitance adjustment unit that adjusts the ratio of C1 and C2 to be equal to the ratio of C3 and C4 within a predetermined error.

2. In Paragraph 1, The above-described capacitance adjustment unit comprises an adjustment capacitor arranged in parallel with the first capacitance unit, in a motor.

3. In any one of paragraphs 1 to 2, The above capacitance adjustment unit is a motor connected in parallel with the floating capacitance formed by the winding and the metal plate in the first capacitance unit.

4. In any one of paragraphs 1 to 3, The above bearing includes a first bearing disposed at the upper end of the shaft and a second bearing disposed at the lower end of the shaft, and The metal plate comprises a first metal plate fixed to the outer ring side of the first bearing and a second metal plate fixed to the outer ring side of the second bearing, wherein An electric motor, wherein the first stage of the capacitance adjustment unit is connected to the neutral point of the winding, and the second stage of the capacitance adjustment unit is connected to the second metal plate.

5. In Paragraph 4, The second stage of the above-mentioned capacitance adjustment unit is connected to a screw hole that fixes the second metal plate and is electrically connected to the second metal plate, the motor.

6. In Paragraph 1, The above-described capacitance adjustment unit comprises an adjustment capacitor disposed in the second capacitance unit, for a motor.

7. In Paragraph 6, The above capacitance adjustment unit is a motor connected in parallel with the floating capacitance formed by the substrate and the metal steel plate in the second capacitance unit.

8. In Paragraph 7, The above bearing includes a first bearing disposed at the upper end of the shaft and a second bearing disposed at the lower end of the shaft, and The metal plate comprises a first metal plate fixed to the outer ring side of the first bearing and a second metal plate fixed to the outer ring side of the second bearing, wherein A motor, wherein the first stage of the capacitance adjustment unit is connected to the ground of the substrate, and the second stage of the capacitance adjustment unit is connected to the second metal plate.

9. In Paragraph 1, The above bearing includes a first bearing disposed at the upper end of the shaft and a second bearing disposed at the lower end of the shaft, and The metal plate comprises a first metal plate fixed to the outer ring side of the first bearing and a second metal plate fixed to the outer ring side of the second bearing, wherein The above capacitance adjustment unit includes a first adjustment capacitor and a second adjustment capacitor, and The first terminal of the first adjustment capacitor is connected to the potential supply point of the substrate, and The first terminal of the second adjustment capacitor is connected to the ground of the substrate, An electric motor in which the second terminal of the first adjustment capacitor and the second terminal of the second adjustment capacitor are connected to the second metal plate.

10. In Paragraph 1, The above capacitance adjustment unit is a motor disposed in the above fourth capacitance unit.

11. In Paragraph 10, Including a casing, The above casing includes the rotor, the stator, the bearing, and the substrate, wherein The above capacitance adjustment unit comprises a metal member installed between the substrate and the shaft in the fourth capacitance unit, in a motor.

12. In Paragraph 11, The above metal member is a ring-shaped motor surrounding the shaft.

13. In any one of paragraphs 10 through 12, The above-mentioned capacitance adjustment unit is connected in parallel with the floating capacitance formed between the substrate and the shaft, in a motor.

14. In any one of paragraphs 1 through 13, A motor in which the ratio of the common mode voltage within the motor is divided as the ratio of C1 and C2 is adjusted to be identical to the ratio of C3 and C4 within a predetermined error.

15. In any one of paragraphs 1 through 14, The above electric motor is an electric motor included in any one of a washing machine, dryer, dishwasher, electric oven, refrigerator, vacuum cleaner, garment care machine, or chiller.

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