Electric motor with suppressed electrically induced bearing damage (EIBD)

Abstract

The present disclosure relates to a motor assembly configured to suppress electrically induced bearing damage (EIBD). More specifically, the motor assembly includes a frame, a stator, a winding coil, a rotor, a shaft, a conductor, circuitry, and an insulator. The circuitry can include one or more transformers that can generate an injection voltage, and the injection voltage can suppress a shaft voltage that causes EIBD.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 381,914, filed on November 1, 2022, titled "ROTOR VOLTAGE CANCELLATION", the disclosure of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] Embodiments of the present disclosure relate to an electric motor. More specifically, embodiments of the present disclosure relate to systems and methods for suppressing electrically induced bearing damage (EIBD) in an electric motor. BACKGROUND OF THE DISCLOSURE

[0004] Electric motors have a wide range of applications, including their use in various types of vehicles, such as electric, internal combustion, and hybrid vehicles. These electric motors operate by converting electrical energy into mechanical energy. This conversion process involves energizing the electric motor, which then generates magnetic fields in two key components - the stator (the stationary component) and the rotor (the rotating component). The interaction between the magnetic fields of the stator and the rotor generates mechanical energy, causing the rotor to rotate. Typically, electric motors are powered using alternating current (AC) in multiple phases, with each phase generating a magnetic field with a different phase. The AC is generated from an inverter, such as a switching inverter. For example, the inverter receives direct current (DC) from an external power source, such as a battery, and converts the DC to AC by switching the DC at various frequencies (e.g., turning the DC on or off). Thus, the switching mechanism of the inverter is capable of generating AC waveforms at various frequencies and phases, and can adjust the speed of the electric motor rotation (e.g., the rotor rotation) by adjusting the frequency of the provided AC.

[0005] Examples of electric motor applications include, but are not limited to, electric vehicles, electric water pumps, electric fans, robotic systems, etc. SUMMARY OF THE DISCLOSURE

[0006] The innovations described in the claims have several aspects, none of which alone is responsible for their desirable attributes. Without limiting the scope of the claims, some important features of the present disclosure will now be briefly described.

[0007] One aspect of the present disclosure is an electric motor assembly that includes: a frame, a stator configured to receive energy from an external energy source, a winding coil configured to generate a magnetic field, wherein the winding coil is implemented within the stator, a rotor magnetically coupled to the stator, a shaft connected to the rotor, a bearing connected between the shaft and the frame, a conductor capacitively coupled to the rotor, a circuit system configured to generate an injection voltage, wherein the circuit system is connected to the winding coil and the conductor, and an insulator connected between the conductor and the frame.

[0008] In a motor assembly, the rotor rotates through a magnetic field generated from a winding coil.

[0009] In a motor assembly, energy is received from an inverter that is capable of providing an alternating current to the motor assembly, and the alternating current can include three waveforms having the same frequency. Additionally, each waveform can have a different phase of 120 degrees.

[0010] In a motor assembly, the circuitry can include a transformer. The transformer can generate injected energy by receiving current from a winding neutral point.

[0011] In a motor assembly, the motor can include parasitic capacitances between the frame and the winding coil, between the winding coil and the rotor, between the stator and the rotor, and across the bearings. A common-mode voltage can generate a shaft voltage between the shaft and the frame. The shaft voltage can be suppressed by an injected voltage.

[0012] In a motor assembly, the circuitry can include a first transformer, a second transformer, a low-pass filter, and a high-pass filter. The first transformer can transmit a high-band signal by receiving energy from a conductor and filtering the energy via the high-pass filter. The second transformer can convert a low-band signal by receiving energy from a winding neutral point and feeding the energy to the conductor.

[0013] In a motor assembly, the motor assembly can be implemented in an electric vehicle.

[0014] Another aspect of the present disclosure is a motor assembly including: a frame; a stator configured to receive energy from an external energy source; a winding coil configured to generate a magnetic field, where the winding coil is implemented within the stator; a rotor magnetically coupled to the stator; a shaft connected to the rotor; a bearing connected between the shaft and the frame; a conductor capacitively coupled to the rotor; a transformer configured to generate an injected voltage, and the transformer is connected to the winding coil and the conductor; and an insulator connected between the conductor and the frame.

[0015] In a motor assembly, the transformer can be integrated on the top side of a printed circuit board (PCB), and the conductor can be integrated on the bottom side of the PCB. Additionally, the transformer can receive energy from a winding neutral point.

[0016] In a motor assembly, the motor can include parasitic capacitances between the frame and the winding coil, between the winding coil and the rotor, between the stator and the rotor, and across the bearings, and a shaft voltage can be generated from one or more of the parasitic capacitances. Additionally, the shaft voltage is suppressed by an injected voltage.

[0017] In a motor assembly, the rotor is capable of rotating based on the switching frequency of an inverter. The inverter is capable of supplying AC to the motor assembly.

[0018] In a motor assembly, the received energy can be an alternating current, and the alternating current can include three waveforms having the same frequency. Additionally, each waveform can have a different phase of 120 degrees. Further, the frequency can be the switching frequency of an inverter configured to supply AC to the motor assembly.

[0019] In a motor assembly, a transformer can be connected to the winding neutral point.

[0020] In a motor assembly, the distance between the conductor and the rotor is determined based on the parasitic capacitance.

[0021] Another aspect of the present disclosure is a method for suppressing EIBD of a motor. The method includes starting the operation of the motor, wherein the motor is started by receiving an input at each phase of the motor; generating a common-mode voltage; generating an axial voltage, wherein the axial voltage is a part of the common-mode voltage; and generating an injection voltage to suppress the axial voltage, wherein the injection voltage is generated from a transformer connected between the winding neutral point and a conductor of the motor, wherein the input of the transformer receives an input signal from the winding neutral point, wherein the output of the transformer is connected to the conductor placed away from the rotor, and the input and output of the transformer have opposite polarities.

[0022] Another aspect of the present disclosure is a circuit system for suppressing EIBD of a motor. The circuit system includes a PCB board, a transformer integrated on top of the PCB board, wherein the transformer is configured to generate an injection voltage, an input configured to supply an input voltage to the transformer, wherein the input is received from the winding neutral point of the motor, and an output of the transformer connected to a conductor of the circuit system, wherein the conductor is implemented at the bottom of the PCB board, and wherein the output and the conductor are connected through a via of the PCB board. The motor can be a motor of an electric vehicle. The output can suppress the voltage generated by the parasitic capacitance of the motor.

[0023] To summarize the present disclosure, certain aspects, advantages, and novel features of the innovation are described herein. It should be understood that not necessarily all of these advantages can be achieved according to any particular embodiment. Thus, the innovation can be implemented or practiced in a manner that realizes or optimizes one or a group of the advantages described herein, without realizing other advantages taught or suggested by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present disclosure is described herein with reference to the accompanying drawings of specific embodiments, which are intended to illustrate rather than limit the present disclosure. It should be understood that the drawings included in this specification and constituting a part of this specification illustrate the concepts disclosed in this specification and may not be drawn to scale.

[0025] Figure 1 An example of a cross-sectional view depicting an embodiment of an electric motor in accordance with one or more aspects of the present application is illustrated;

[0026] Figure 2A A two-dimensional view of a conventional electric motor is depicted;

[0027] Figure 2B A schematic view of a conventional electric motor is illustrated;

[0028] Figure 3A A two-dimensional view of an electric motor in accordance with one or more aspects of the present application is depicted;

[0029] Figure 3B A schematic view of an electric motor in accordance with one or more aspects of the present application is illustrated;

[0030] Figure 4A The rotor voltage corresponding to the operation of a conventional electric motor is illustrated;

[0031] Figure 4B The rotor voltage corresponding to one or more aspects of the present application is illustrated;

[0032] Figure 5 An example of a circuit system having a smaller form factor is illustrated;

[0033] Figure 6 An example of a flowchart of a circuit system for implementing suppression of shaft voltage in accordance with one or more aspects of the present application is illustrated;

[0034] Figures 7A - 7C An exemplary method for determining the parasitic capacitance of an electric motor is illustrated; and

[0035] Figure 8 An example of operating an electric motor by implementing a circuit system to significantly reduce (e.g., significantly minimize) the shaft voltage in accordance with one or more aspects of the present application is illustrated. Detailed Description

[0036] Although certain preferred embodiments and examples are disclosed below, the subject matter of the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses and their modifications and equivalents. Accordingly, the scope of the appended claims is not limited to any of the specific embodiments described below. For example, in any of the methods or processes disclosed herein, the acts or operations of the method or process may be performed in any suitable order and are not necessarily limited to any particular disclosed order. The various operations may be described in turn as a number of discrete operations in a manner that may be helpful in understanding the specific embodiments; however, the order of description should not be construed as implying that these operations are dependent on the order. Additionally, the structures, systems, and / or devices described herein may be implemented as integrated components or as separate components. To compare various embodiments, certain aspects and advantages of these embodiments are described. Not all of these aspects or advantages must be achieved by any particular embodiment. Thus, for example, the various embodiments may be implemented in a manner that achieves or optimizes one or a group of the advantages described herein without achieving the other aspects or advantages described or suggested herein.

[0037] As the demand for electric motors grows, there is increasing interest in developing electric motors that can operate with a long lifespan. Therefore, it is crucial to reduce the wear of components. For example, an electric motor that utilizes the magnetic field interaction between the stator and the rotor can effectively reduce wear. This is because these two components do not come into physical contact, thereby eliminating the friction between them.

[0038] However, the operation of an electric motor can generate electrically induced bearing damage (EIBD). More specifically, an electric motor can receive energy (e.g., AC) from an inverter (e.g., a switched inverter). The inverter is configured to convert DC to AC, and the AC is used as the energy source for the motor. The inverter is capable of generating AC by performing switching operations. A typical steel bearing installed in a motor powered by a switched inverter will wear prematurely. This is caused by the common-mode voltage inherent in the operation of the switched inverter and is partially captured by the rotor because some parts of the rotor are exposed to windings that are subject to the inverter voltage. Electrically induced bearing damage (EIBD) occurs when the rotor (and subsequently the shaft) voltage rises above a threshold voltage (e.g., 3.5 volts with respect to the voltage of the frame (which is typically the same as the ground voltage)). In this case, the thin insulating lubricating oil film on the bearing balls may rupture and form an electric arc. Consequently, the accumulated charge may discharge on the rotor through the substantially restricted points between the bearing balls and the raceway, thereby generating minute welds, essentially initiating electrical discharge machining (EDM). As the bearing operates, this weld is subsequently pulled up, at which time deformation exists on both the ball and raceway surfaces. This process repeats in a random manner during each switching cycle. This phenomenon is more severe when the DC voltage connected to the inverter is high and when the switching frequency is high because all parts of the circuit are substantially interconnected through parasitic capacitance. Parasitic capacitance refers to the capacitance formed between two conductors, even if not intended by the designer.

[0039] Traditionally, to reduce or minimize electrically induced bearing damage, the rotor can be physically grounded, allowing the current generated by the parasitic capacitance to flow to ground rather than through the rotor and shaft into the bearing. For example, the rotor of the motor and the chassis (which serves as the ground for the motor) are electrically connected through a conductive ball bearing between the rotor and the stator. In another method, a conductive brush is used around the shaft to establish electrical contact with the motor chassis. However, due to the inconsistent nature of the conductive compound inside the bearing, these traditional methods result in technical limitations. Additionally, implementing the brush may limit the operating life of the motor depending on the life of the brush. For example, the brush physically contacts one or more components of the motor, thereby causing an undesirable wear problem on the brush due to physical contact (e.g., friction between components). Other traditional methods (such as using insulated bearings or chokes) also have technical limitations and cannot address the root cause of generating unnecessary voltage due to parasitic capacitance.

[0040] The present disclosure provides a technical solution for suppressing EIBD. More specifically, the present disclosure provides a method for suppressing unwanted voltages generated during the operation of an electrical device application (such as an electric motor). Additionally, the technical solution provided herein addresses the root cause of EIBD by minimizing or suppressing unwanted voltages without implementing hardware that requires wearing out motor components.

[0041] In some aspects of the present disclosure, a motor can include circuitry capable of generating a voltage (e.g., an injection voltage) to suppress an unwanted voltage. For example, a common-mode voltage generated by the switching operation of an inverter that supplies energy to the motor can cause an unwanted voltage (shaft voltage) to be generated on the motor shaft. In some examples, the circuitry can generate an injection voltage having an opposite polarity to the shaft voltage (e.g., an unwanted voltage that causes EIBD). For example, when the shaft voltage reaches a positive voltage, the injection voltage can reach a negative voltage that is the same or similar in absolute magnitude to the shaft voltage. Additionally, when the shaft voltage reaches a negative value, the injection voltage can reach a positive value having the same absolute value as the shaft voltage. In some embodiments, an injection voltage can be generated to keep the shaft voltage below a threshold voltage that causes EIBD, such as a threshold voltage of about 3.5 volts. As a result, the shaft voltage can be reduced to zero, close to zero, or below the threshold voltage. This helps to minimize or completely eliminate electrically induced bearing damage.

[0042] In some embodiments of the present disclosure, one or more transformers are used as a source of the injection voltage. By way of illustration, a conductor plate is capacitively coupled to the rotor, and the transformer receives its energy source through conductive coupling with a winding neutral (e.g., the winding neutral point of a winding coil) and ground (e.g., the frame of the motor). For example, when the motor is operating, the conductor and the rotor can be capacitively coupled. Thus, the energy source of the transformer can be a connection between the winding neutral point of the winding coil and a ground source (e.g., the frame of the motor). By utilizing this energy source, the transformer generates an injection voltage that can be used to suppress the shaft voltage.

[0043] One or more aspects of the present disclosure relate to a method of suppressing EIBD by minimizing or eliminating the shaft voltage. In some embodiments, the method can include determining the parasitic capacitance of the motor. As disclosed herein, parasitic capacitance is generated due to capacitive coupling between motor components. After determining the parasitic capacitance, the present disclosure provides a method of implementing a transformer and a conductor. More specifically, the present disclosure provides methods for determining the conductor size, transformer parameters, and the distance between the conductor and the rotor. In some embodiments, the transformer and the conductor are implemented on a printed circuit board (PCB). For example, one side of the PCB can employ a conductive material, while the other side of the conductive material can employ a transformer. In this example, the conductive material is capacitively coupled to the rotor and serves as the conductor. Additionally, in this example, the transformer and the conductive material are connected by vias, such that the transformer can transfer energy to the conductive material from the via connection.

[0044] Some aspects of the present disclosure provide various transformer designs that can be implemented in an electric motor. In some embodiments, the size of the transformer can be minimized by using more than one transformer alongside various filters (such as low-pass filters and high-pass filters). For example, two transformers can be implemented in the same circuit, one for high-frequency energy signals and the other for low-frequency signals. This approach has the advantage of minimizing the size of the transformer circuitry. For example, a single transformer that can cover both high and low frequencies may have a large form factor and may not be implementable in the motor. However, using multiple transformers may reduce the form factor of the transformer circuitry.

[0045] Although the various aspects will be described in accordance with combinations of exemplary embodiments and features, those skilled in the relevant art will understand that these combinations of examples and features are exemplary in nature and should not be construed as restrictive. More specifically, the aspects of the present application are applicable to various types of applications, and each application may require different specifications for the electric motor. For example, the specifications of a fan motor are different from those of an electric bed motor. Therefore, the illustrative examples should not be construed as limiting.

[0046] Figure 1 An example of a cross-sectional view depicting an embodiment of an electric motor as disclosed herein is illustrated. As Figure 1 shown, the electric motor can be assembled with a frame 102, which can include a stator 104, a rotor 106, a shaft 108, and bearings 110. The stator 104 can include coils 112. In some embodiments, an alternating current (AC) can be applied to the coils 112 included in the stator 104, and the coils 112 can generate a magnetic field due to the received AC. In some embodiments, the AC is provided as a polyphase waveform. For example, if there are three phases, the magnetic field generated on the coils can include three different magnetic fields, and each magnetic field corresponds to each phase. In some examples, the AC can be provided by an external power source, such as an inverter connected to a battery, a power outlet, etc. In some embodiments, the electric motor is connected to an inverter 150. For example, the inverter 150 is configured to provide AC to the electric motor by connecting to a ground source (such as the frame 102). The inverter 150 can be configured to generate the required AC by converting the AC received from an external power source (e.g., a power outlet, a battery, etc.). The inverter 150 can be configured to generate an AC waveform having multiple different phases (such as 3 phases), each waveform having a 120-degree phase difference (at the same frequency). Additionally, the switching frequency of the inverter can be associated with the waveform frequency. In some examples, the frequency of the inverter is proportionally related to the rotational speed of the rotor 106 and the shaft 108.

[0047] The applied voltage can generate current. The current can generate a magnetic field. These magnetic fields can generate a rotating magnetic field based on different phases. The rotating magnetic field can induce current on the rotor 106, and the rotor 106 can be rotated due to the rotating magnetic field. In some embodiments, the shaft 108 can be assembled with the rotor 106, and rotating the rotor 106 can cause the shaft 108 to rotate. As further described in Figure 1 The shaft 108 and the frame 102 are assembled with the bearings 110.

[0048] The motor 100 can additionally include a transformer 114, a capacitor 116, an insulator 120, and a conductor 122. As described in this agreement, these additional components can be used to suppress EIBD. For example, the transformer 114 is connected between the winding neutral point 124 and the conductor 122. Without being limited by theory, the neutral line can ground the source because the source (e.g., battery, power socket, etc.) can be capacitively coupled to the ground through the parasitic capacitance inherent between physical conductors. In some examples, during operation of the motor 100 (e.g., when the rotor 106 rotates), the conductor 122 and the rotor 106 are capacitively coupled. In some examples, the transformer 114 can generate an injection voltage to suppress the shaft voltage (e.g., the voltage between the shaft 108 and the frame 102) and induce current through the conductor 122 into the rotor 106. This injection voltage can suppress the shaft voltage, Vshaft (see Figure 2B and Figure 3B ). A detailed description of suppressing the shaft voltage is as follows.

[0049] As further described in Figure 1 Since the rotor 106 and the shaft 108 rotate due to the rotating magnetic field generated by the induction coil 112, these components have no physical contact. Therefore, the motor 100 can be a permanent magnet motor.

[0050] The motor 100 can be applied to an electric vehicle. However, the present disclosure does not limit the application of the motor 100, and it can be applied to any suitable application.

[0051] Figure 2A and 2B illustrate a two-dimensional view of a conventional motor 200. As Figure 2A shown, the conventional motor 200 can be assembled with a frame 202, and the frame 202 can include a stator 204, a rotor 206, a shaft 208, and bearings 210. The stator 204 can include coils 212. As Figure 2AAs shown, during the operation of the electric motor 200, there is a parasitic capacitance between two components. For example, when power is applied to the electric motor 200 (e.g., power is applied from an inverter), the DC voltage supplied to the inverter can cause a common-mode voltage between the winding coil 212 (e.g., the winding neutral point of the winding coil) and ground (e.g., the frame 202). This common-mode voltage can be Figure 2A used to charge the parasitic capacitances Cwg, Cwr, Crg, and Cb shown. For example, the common-mode voltage can charge the parasitic capacitance coupling Cwg between the winding coil 212 and the frame 202. The common-mode voltage can also charge the parasitic capacitance coupling Cwr between the coil 212 and the rotor 206. Additionally, the common-mode voltage can charge the parasitic capacitance coupling Crg between the rotor 206 and the frame 202 (e.g., the stator 204 is physically in contact with the frame). In some embodiments, Crg is related to the induced current from the stator to the rotor. Furthermore, as Figure 2B shown, Crg and Cb are in parallel and in series with Cwr. Therefore, the higher the value of Crg, the lower the shaft voltage Vshaft. In some embodiments, by charging Cwr and Crg, due to the induced current on the rotor 206, a voltage can be induced on the shaft 208. This induced voltage can charge the parasitic capacitance coupling Cb between the chassis 202 and the shaft 208. These parasitic capacitance couplings Cwg, Cwr, Crg, and Cb may generate an unwanted voltage, Vshaft, between the shafts, and Vshaft may cause damage to the bearing 210. This kind of damage is usually referred to as EIBD.

[0052] Figure 2B The figure illustrates Figure 2A a schematic diagram of Figure 2B As shown, part 252 corresponds to the coil 212, part 254 corresponds to the frame 202. Additionally, part 256 corresponds to the rotor 206. During the operation of the electric motor 200, the voltage applied to the winding neutral point 224 from Figure 1 the inverter 150 shown can generate a common-mode voltage, Vcm. Due to the parasitic capacitance, a part of the common-mode voltage, Vcm, can generate a shaft voltage, Vshaft, as Figure 2B shown.

[0053] To suppress the shaft voltage Vshaft generated by the parasitic capacitance, the present disclosure provides an electric motor 300 by implementing additional circuitry, conductors, and insulators, as Figure 3A described therein. Figure 3A The figure illustrates Figure 1 a two-dimensional view of the electric motor shown.

[0054] As Figure 3AAs shown, the frame 302 of the electric motor 300 can be assembled with the stator 304, the rotor 306, the shaft 308, the bearings 310, and the coil 312. In addition, the electric motor 300 can include a transformer 314, an insulator 320, and a conductor 322. In some embodiments, the transformer 314 can be configured to generate an injection voltage. The injection voltage can be configured to suppress the shaft voltage. For example, the injection voltage has a polarity opposite to that of the shaft voltage. Therefore, the shaft voltage can be suppressed. For example, during operation of the rotor 306 (e.g., during rotation of the rotor), the conductor 322 can be capacitively coupled to the rotor 306 (e.g., capacitive coupling, Ccond). For example, the rotor 306 can generate an electric field during its rotation that can be coupled to the conductor 322. The capacitance of the capacitor can be determined based at least on the distance between the conductor 322 and the rotor 306. In some examples, the transformer 314 can receive an input from the winding neutral point 324 and convert the input into an output between the conductor 322 and the frame 302. In some embodiments, the output voltage can have a polarity opposite to that of the input voltage. By utilizing this input power supply, the transformer 314 can generate an injection voltage (e.g., the output voltage). In some examples, the injection voltage, Vinjected (the output of the transformer 314) can charge the capacitance existing between the conductor 322 and the rotor 306. Since the induced current of Vinjected can flow via Ccond, this current and Ccond can generate a voltage drop across Ccond. Therefore, in some embodiments, Ccond can be related to Crg, and thus, the shaft voltage, Vshaft, can be reduced. In some examples, the distance between the conductor 322 and the rotor 306 determines the amount of current flowing through the coil, and this distance can be determined based on Vshaft.

[0055] In some cases, the transformer 314 can be implemented as a circuit system. For example, the transformer 314 can be integrated with a PCB and connected to the winding neutral line 324 of the coil 312 and the frame 302. In some cases, the circuit system can include additional passive electrical components, such as resistors and / or capacitors. These electrical components can be determined according to the required output of the transformer. For example, if the transformer 314 is configured to operate in a specific frequency band, one or more of these electrical components can be implemented as a frequency filter (e.g., a high-pass filter or a low-pass filter). In some examples, the circuit system can include the transformer 314 and the conductor 322. For example, one side of the PCB can include a layer of the conductor 322, and the other side of the PCB can include the transformer 314. The electric motor 300 can also include an insulator 320.

[0056] Figure 3B is illustrated Figure 3A a schematic diagram of. As Figure 3BAs shown, portion 352 corresponds to coil 312, portion 354 corresponds to frame 302. Additionally, portion 356 corresponds to rotor 306. Additionally, portion 358 corresponds to conductor 322. As Figure 3B shown, transformer 314 can generate an injection voltage, Vinjected. The injection voltage, Vinjected has a polarity opposite to that of the common-mode voltage, Vcm. Thus, the shaft voltage Vshaft can be canceled (e.g., suppressed) by applying the injection voltage, Vinjected. In some embodiments, the amount of the injection voltage Vinjected can be adjusted based on the value of Ccond. Thus, the distance between conductor 322 and rotor 306 can be determined based on the amounts of the common-mode voltage, Vcm and the shaft voltage, Vshaft. For example, the capacitance of the coil is inversely proportional to the distance between conductor 322 and rotor 306.

[0057] Figure 4A and Figure 4B illustrates a comparison example of the shaft voltage, Vshaft 420 during motor operation (e.g., the voltage between the rotor and the frame since the rotor and the shaft are conductively connected). Figure 4A corresponds to Figure 2A and 2B the operation of the motor 200 shown. As Figure 4A shown, a portion of the common-mode voltage 422, Vcm is induced on the rotor, such as the shaft voltage (Vshaft). For example, the common-mode voltage 422, Vcm is generated by the inverter (150) and averaged at the winding neutral point 224 (as Figure 2A shown), thus, Figure 4A illustrates a similar pattern between the common-mode voltage 422, Vcm and the winding neutral point voltage 424 (e.g., Figure 2A the voltage appearing on the winding neutral line 224 of Figure 4A shown). The motor 200 does not include a transformer for suppressing the shaft voltage, Vshaft. Thus, as

[0058] Figure 4B corresponds to Figure 3A and 3B the operation of the motor 300 illustrated. As described in Figure 4B there is a common-mode voltage 452, Vcm generated from a DC inverter (e.g., power supply) connected to the motor 300 (shown in Figure 3A ). Additionally, the common-mode voltage 452, Vcm can have a pattern similar to that of the winding neutral point voltage 454 (e.g., the voltage appearing on the winding neutral point 324 of the inverter in Figure 3A ). AsFigure 4B As shown, the shaft voltage 450, Vshaft caused by the common-mode voltage 452, Vcm is suppressed by the injected voltage, Vinjected, as Figure 3B shown. Thus, as Figure 4B shown, the shaft voltage 450, Vshaft (e.g., the voltage at the rotor) can be close to zero. In some embodiments, this voltage can be equal to or lower than a threshold voltage, such as a voltage that may cause EIBD.

[0059] In some embodiments, the transformer 314 can be designed to operate over a wide frequency range. For example, the bandwidth of the frequency range can be from dozens of kHz to hundreds of MHz. This frequency range can be determined based on the switching frequency of the inverter. In some embodiments, the transformer 314 designed to operate over a wide frequency range can have a larger form factor. Thus, in some applications where the motor size is limited, a smaller form factor of the transformer 314 is desirable. The switching frequency of the inverter can be determined based on the specific application, and the present disclosure does not limit the frequency range.

[0060] Figure 5 An example of a circuit system 500 with a smaller form factor is illustrated. As Figure 5 shown, the circuit system 500 can include two transformers T1 and T2. Each transformer can be configured to operate within a specific frequency band, so the combined size of T1 and T2 can be smaller than that of a single transformer that can operate over a wide frequency range. The circuit system can receive an input by connecting point A to the winding neutral point 324 ( Figure 3A shown) and connecting point G to the frame 302. The output of the circuit system 500 can correspond to point G connected to the frame 302 and point B connected to the conductor 322. Thus, the output voltage of the circuit system can generate a voltage opposite to the input voltage. In addition, the circuit system 500 can include a combination of a low-pass filter and a high-pass filter. Thus, the input signal (generated between point A and point G) can be filtered based on its frequency and provided to one of the transformers T1 or T2. For example, T2 can have a larger number of transformer coils than T1 and be configured to transform low-frequency band signals, and T1 can be configured to transform high-frequency band signals. In this example, the combination of C1 and R1 can filter the low-frequency band of the input signal and provide the filtered signal to T1. In addition, the combination of R1 and C2 can filter the high-frequency band of the input signal and provide the filtered signal to T2. R2 can be implemented as an output load to generate an output voltage between point B and point G. Thus, by using a combination of multiple small transformers and frequency filters, the form factor of the transformer can be minimized. The present disclosure does not limit the values of C1, C2, R1, R2, T1, and T2, and these values can be determined based on the specific application.

[0061] Figure 6 Illustrated is an example of implementing one or more transformers on a motor assembly to suppress shaft voltage. By reference Figure 1 、 Figure 2A and 2B 、 Figure 3A and 3B as well as Figures 7A - 7C to describe Figure 6 。

[0062] At block 610, the motor receives input energy from an inverter (such as the inverter 150 shown Figure 1 ). In some embodiments, an alternating current (AC) may be applied to the coils 112 included in the stator 104, and the coils 112 may generate a magnetic field due to the received AC. The AC is generated by an inverter (such as a switched inverter). For example, the inverter receives DC from an external power source (such as a battery) and converts the DC to AC by switching the DC at different frequencies (e.g., turning the DC on or off). Thus, the switching mechanism of the inverter is capable of generating AC waveforms of various frequencies and phases and is capable of adjusting the rotational speed of the motor (e.g., rotor rotation) by adjusting the frequency of the supplied AC.

[0063] At block 620, the shaft voltage can be determined by measuring the parasitic capacitances Cwg, Cwr, and Crg. These capacitances can vary depending on the specific application, and those of ordinary skill in the art can measure these capacitances. For example, as Figure 7A shown, the total capacitance C1 can be measured, and C1 can represent the combined capacitance of Cwg and Crg. Then, as Figure 7B shown, the total capacitance C2 can be measured, and C2 can represent the combined capacitance of Cwr and Crg. The shaft voltage can be measured based on the measured common-mode voltage, Vcm, and the capacitances in Figure 7A and Figure 7B .

[0064] At block 630, the motor determines one or more transformers to suppress the shaft voltage. In some embodiments, the transformer 314 can be configured to generate an injection voltage, as Figure 3B shown. The injection voltage can be configured to suppress the shaft voltage, for example, an injection voltage having a polarity opposite to that of the shaft voltage, and thus, the shaft voltage can be suppressed. The transformer can be designed based on the required injection voltage. In some embodiments, a single transformer can be implemented to generate the injection voltage. In some embodiments, multiple transformers can be implemented to reduce the form factor with a wide bandwidth. Figure 5 An example of implementing two transformers is described in

[0065] At block 640, the determined transformer(s) can be implemented in the motor. For example, the input of the transformer can be connected between the winding neutral point 324 and the frame 302, as Figure 3Aas shown. In other examples, two transformers can be implemented in a motor, such as Figure 5 as described in

[0066] Figure 8 illustrates an example of operating a motor, such as in Figure 3A and 3B as described. The motor can implement a circuit system configured to generate an injection voltage to suppress the shaft voltage of the motor.

[0067] At block 810, the motor starts operating. The motor receives input energy from an inverter (such as Figure 1 the inverter 150 shown). In some embodiments, an alternating current (AC) can be applied to the coils 112 included in the stator 104, and the coils 112 can generate a magnetic field due to the received AC. The AC is generated by an inverter (such as a switched inverter). For example, the inverter receives DC from an external power source (such as a battery) and converts the DC to AC by switching the DC at different frequencies (such as turning the DC on or off). Thus, the switching mechanism of the inverter can generate AC waveforms of various frequencies and phases, and can adjust the rotational speed of the motor (e.g., the rotor rotates) by adjusting the frequency of the provided AC.

[0068] At block 820, the operation of the motor generates a common-mode voltage. When performing the switching operation, the common-mode voltage may be caused by the inverter. For example, as described in Figure 4B a common-mode voltage 452 is generated at the winding neutral point 324 (shown in Figure 3A ).

[0069] At block 830, the operation of the motor generates a shaft voltage. As Figure 4A described, the shaft voltage 420 can be a part of the common-mode voltage 422.

[0070] At block 840, the operation of the motor generates an injection voltage. In some embodiments, the circuit system can include one or more transformers. In some embodiments, the transformer 314 ( Figure 3A shown) can be configured to generate an injection voltage, as Figure 3B shown. The injection voltage can be configured to suppress the shaft voltage, such as the injection voltage having a polarity opposite to that of the shaft voltage, and thus, the shaft voltage can be suppressed. The transformer can be designed based on the required injection voltage. In some embodiments, a single transformer can be implemented to generate the injection voltage. In some embodiments, multiple transformers can be implemented to reduce the form factor with a wide bandwidth. Figure 5 Examples of implementing two transformers are described in

[0071] When a feature or element is referred to herein as being "on" another feature or element, it can be directly on the other feature or element or intervening features and / or elements may be present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, intervening features or elements may not be present. It should also be understood that when a feature or element is referred to as being "connected", "attached" or "coupled" to another feature or element, it can be directly connected, attached or coupled to the other feature or element, or intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected", "directly attached" or "directly coupled" to another feature or element, intervening features or elements may not be present.

[0072] Although one embodiment has been described or shown with respect to, the features and elements so described or shown are applicable to other embodiments. Those skilled in the art will also understand that when a structure or feature is referred to as being "adjacent" another feature, it may have portions that overlap or are located beneath the adjacent feature.

[0073] The terms used herein are for the purpose of describing particular embodiments and implementations only and are not limiting. For example, the singular forms "a", "an" and "the" used herein may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of the stated features, steps, operations, processes, functions, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, processes, functions, elements, components, and / or combinations thereof. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items and may be abbreviated as " / ".

[0074] In the foregoing description and claims, phrases such as "at least one" or "one or more" may appear after a list of conjunctive elements or features. The term "and / or" may also appear in a list of two or more elements or features. Unless there is some other express or implied contradiction in the context in which it is used, this phrase is intended to refer to any of the listed elements or features individually, or any combination of any of the listed elements or features with any other listed element or feature. For example, the phrases "at least one of A and B", "one or more of A and B", "A and / or B" all refer to "A alone, B alone, or A and B together". Similar interpretations apply to lists containing three or more items. For example, the phrases "at least one of A, B and C", "one or more of A, B and C"; "A, B and / or C" all refer to "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together". The term "based on" as used above and in the claims is intended to mean "at least partially based on", thus also allowing features or elements not recited.

[0075] For ease of description, spatial relative terms may be used herein, such as "front", "back", "lower", "beneath", "below", "upper", "above", etc., to describe the relationship of one element or feature to another element or feature, as shown in the figures. It should be understood that the spatial relative terms are intended to cover directions different from those shown in the figures during the use or operation of the device. For example, if the device in the figures is inverted, then due to the inverted state, an element described as "beneath" or "under" other elements or features will be oriented "above" the other elements or features. Thus, the term "beneath" may include both upward and downward directions depending on the reference point or orientation. The device may be oriented in other ways (rotated 90 degrees or other orientations), and the spatial relative descriptors used herein are to be interpreted accordingly. Similarly, unless otherwise explicitly stated, terms such as "upward", "downward", "vertical", "horizontal", etc. are only for purposes of interpretation.

[0076] Although the terms "first" and "second" may be used herein to describe various features / elements (including steps or processes), these features / elements should not be limited by these terms to an order of the features / elements or that one is primary or more important than the other unless the context otherwise indicates. These terms may be used to distinguish one feature / element from another. Thus, the first feature / element discussed may be termed the second feature / element, and similarly, the second feature / element discussed below may be termed the first feature / element without departing from the teachings provided herein.

[0077] As used in this specification and the claims, including in the examples used, unless otherwise explicitly specified, all numbers are to be understood as being preceded by the term "about" or "approximately" even if the term does not explicitly appear. When describing magnitudes and / or positions, the phrase "about" or "approximate" may be used to indicate that the described value and / or position is within a reasonable expected range of values and / or positions. For example, the value of a numerical value may be + / −0.1%, + / −1%, + / −2%, + / −5%, + / −10%, etc. of the specified value (or numerical range). Unless the context otherwise indicates, any numerical value given in this agreement should also be understood to include about or approximate that numerical value.

[0078] For example, if the value "10" is disclosed, then "about 10" is also disclosed. Any numerical range described herein is intended to include all sub-ranges subsumed therein. It should also be understood that when a value is disclosed, "less than or equal to" that value, "greater than or equal to" that value, and the possible ranges therebetween are also disclosed, as would be appropriately understood by those skilled in the art. For example, if the value "X" is disclosed, then "less than or equal to X" and "greater than or equal to X" are also disclosed (e.g., where X is a numerical value). It should further be understood that throughout the application, data is provided in a variety of different formats, and such data can represent ranges of endpoints or starting points and any combination of data points. For example, if a particular data point "10" and a particular data point "15" can be disclosed, then it should be understood that greater than, greater than or equal to, less than, less than or equal to 10 and 15, and between 10 and 15 can be considered disclosed. It should also be understood that each unit between two particular units can be disclosed. For example, if 10 and 15 can be disclosed, then 11, 12, 13, and 14 can also be disclosed.

[0079] Although various exemplary embodiments have been disclosed, various changes can be made to the various embodiments without departing from the teachings of the present invention. For example, in different or alternative embodiments, the order of performing the various method steps can be changed or reconfigured, and in other embodiments, one or more method steps can be entirely omitted. Optional or desired features of the various device and system embodiments can be included in some embodiments and not in others. Accordingly, the foregoing description has been provided primarily for purposes of illustration and should not be construed as limiting the scope of the claims and the specific embodiments or specific details or features disclosed.

[0080] The examples and illustrations included herein show specific embodiments by way of illustration and not limitation that may practice the disclosed subject matter. As described above, other embodiments can be utilized and other embodiments can be derived therefrom, such that structural and logical substitutions and changes can be made without departing from the scope of the present disclosure. Such embodiments of the disclosed subject matter may be referred to herein individually or collectively by the term "invention," solely for convenience and not with the intention of voluntarily limiting the scope of this application to any single invention or inventive concept (if in fact multiple inventions or inventive concepts are disclosed). Accordingly, although specific embodiments have been shown and described herein, any arrangement that is intended to achieve an intended, actual, or disclosed purpose, whether explicit or implicit, may substitute for the specific embodiments shown. The present disclosure is intended to cover any and all adaptations or variations of the various embodiments. Combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art after reading the foregoing description.

[0081] The disclosed subject matter has been provided with reference to one or more features or embodiments. Those skilled in the art will recognize and understand that, although the exemplary embodiments provided herein are of a detailed nature, changes and modifications can be made to the embodiments without limitation or departure from the generally expected scope. These and various other adaptations and combinations of the embodiments provided herein are within the scope of the disclosed subject matter as defined by the disclosed elements and features and their full equivalents.

Claims

1. A motor assembly, comprising: A frame; A stator configured to receive energy from an external energy source; A winding coil configured to generate a magnetic field, wherein the winding coil is implemented within the stator; A rotor magnetically coupled to the stator; A shaft connected to the rotor; Bearings connected between the shaft and the frame; A conductor capacitively coupled to the rotor; And A circuit system configured to generate an injection voltage, wherein the circuit system is connected to the winding coil and the conductor.

2. The motor assembly according to claim 1, wherein the rotor rotates by the magnetic field generated from the winding coil.

3. The motor assembly according to claim 1, wherein the energy is received from an inverter configured to supply an alternating current to the motor assembly, and wherein the alternating current comprises three waveforms having the same frequency.

4. The motor assembly according to claim 3, wherein each waveform has a different phase of 120 degrees.

5. The motor assembly according to claim 1, wherein the circuit system comprises a transformer configured to generate injection energy by receiving current from a winding neutral point.

6. The motor assembly according to claim 1, wherein the motor comprises parasitic capacitance between the frame and the winding coil, between the winding coil and the rotor, between the stator and the rotor, and across the bearings, and wherein a common-mode voltage generates a shaft voltage between the shaft and the frame.

7. The motor assembly according to claim 6, wherein the shaft voltage is suppressed by the injection voltage.

8. The motor assembly according to claim 1, wherein the circuit system comprises a first transformer, a second transformer, a low-pass filter, and a high-pass filter, and wherein the first transformer is configured to transmit a high-band signal by receiving energy from the conductor and filtering the energy via the high-pass filter, and wherein the second transformer is configured to convert a low-band signal by receiving the energy from the winding neutral point and feeding the energy to the conductor.

9. The motor assembly according to claim 1, wherein the motor assembly is implemented in an electric vehicle.

10. A motor assembly, comprising: A frame; A stator configured to receive energy from an external energy source; A winding coil configured to generate a magnetic field, wherein the winding coil is implemented within the stator; A rotor magnetically coupled to the stator; A shaft connected to the rotor; Bearings connected between the shaft and the frame; A conductor capacitively coupled to the rotor; And One or more transformers configured to generate an injection voltage, wherein the transformers are connected to the winding coil and the conductor.

11. The motor assembly according to claim 10, wherein the transformer is integrated on the top side of a printed circuit board (PCB), and wherein the conductor is integrated on the bottom side of the PCB.

12. The motor assembly according to claim 11, wherein the transformer receives energy from the winding neutral point.

13. The motor assembly according to claim 10, wherein the motor includes parasitic capacitances between the frame and the winding coils, between the winding coils and the rotor, between the stator and the rotor, and across the bearings, and wherein shaft voltage is generated from one or more of the parasitic capacitances.

14. The motor assembly according to claim 13, wherein the shaft voltage is suppressed by the injection voltage.

15. The motor assembly according to claim 10, wherein the rotor rotates based on the switching frequency of an inverter, wherein the inverter is configured to supply AC to the motor assembly.

16. The motor assembly according to claim 10, wherein the received energy is an alternating current, and wherein the alternating current includes three waveforms having the same frequency.

17. The motor assembly according to claim 16, wherein each waveform has a different phase of 120 degrees.

18. The motor assembly according to claim 16, wherein the frequency is the switching frequency of an inverter, the inverter being configured to supply AC to the motor assembly.

19. The motor assembly according to claim 10, wherein the transformer is connected to the winding neutral point.

20. The motor assembly according to claim 10, wherein the distance between the conductor and the rotor is determined based on the parasitic capacitance.

21. A method for suppressing EIBD of a motor, the method comprising: Starting operation of the motor, wherein the motor is started by receiving an input at each phase of the motor; Generating a common-mode voltage; Generating a shaft voltage, wherein the shaft voltage is a part of the common-mode voltage; and Generating an injection voltage to suppress the shaft voltage, wherein the injection voltage is generated from a transformer connected between the winding neutral point and a conductor of the motor, wherein the input of the transformer receives an input signal from the winding neutral point, wherein the output of the transformer is connected to the conductor placed away from the rotor, and wherein the input and the output of the transformer have opposite polarities.

22. A circuit system configured to suppress EIBD of a motor, the circuit system comprising: A PCB board; A transformer integrated on top of the PCB board, wherein the transformer is configured to generate an injection voltage; An input configured to supply an input voltage to the transformer, wherein the input is received from the winding neutral point of the motor; And The output of the transformer, connected to a conductor of the circuit system, wherein the conductor is implemented at the bottom of the PCB board, and wherein the output and the conductor are connected through a via of the PCB board.

23. The circuit system according to claim 22, wherein the motor is a motor of an electric vehicle.

24. The circuit system according to claim 22, wherein the output suppresses the voltage generated by the parasitic capacitance of the motor.

25. The circuit system according to claim 22, wherein the output suppresses the shaft voltage.

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