Integrated eddy current sensor, motor and motor shaft corrosion resistance method

Abstract

The application provides an integrated eddy current sensor, a motor and a motor rotating shaft corrosion resisting method. The integrated eddy current sensor comprises a shell assembly, the shell assembly has a containing cavity, part of the shell assembly is connected with a motor rotating shaft, a PCB board is arranged in the containing cavity, and a resin filling part is filled in the containing cavity to seal the PCB board in the shell assembly; wherein the middle part of the shell assembly, the PCB board and the resin filling part is provided with a through hole structure for the motor rotating shaft to pass through. The application innovatively integrates the eddy current sensor and the conductive structure, monitors and leads out the shaft current, actively suppresses the shaft voltage, optimizes the arrangement space, reduces the corrosion of the shaft voltage on the bearing, and improves the electric drive quality.

Description

Technical Field

[0001] This invention relates to the field of integrated eddy current sensors, and more specifically, to an integrated eddy current sensor, a motor, and a method for corrosion protection of the motor shaft. Background Technology

[0002] With the application of high-voltage 800V and above platforms and high-frequency PWM technology in electric drive systems, common-mode voltage is generated by the inverter switching action and coupled to the shaft through the internal parasitic capacitance of the motor, forming shaft voltage. When the shaft voltage exceeds the breakdown threshold of the bearing lubricating oil, which is typically 15-30V / μm, it will break down the oil film, forming shaft current. This leads to electrochemical corrosion, pitting, groove formation, and blackening of the bearing, ultimately causing noise, vibration, or even bearing seizure. Studies show that bearing failures caused by shaft current account for more than 40% of the failure rate of high-voltage electric drives. In terms of bearing protection, although insulated bearings using ceramic materials or surface coatings can block the current path, there is a risk of high-frequency breakdown (the breakdown probability is >15% under 100kHz conditions) and the cost is 3-5 times that of ordinary bearings. Passive current conduction technology conducts current through grounding brushes, but the contact resistance changes by more than 200% under vibration conditions, and carbon brush wear powder contaminates the inside of the motor. These technologies each have inherent defects such as the contradiction between accuracy and reliability, insufficient dynamic response, excessive cost, or short lifespan, making it difficult to meet the stringent requirements of shaft current management for 800V and above high-voltage platforms. Summary of the Invention

[0003] The main objective of this invention is to provide an integrated eddy current sensor, a motor, and a method for corrosion resistance of the motor shaft, in order to solve the problem of short lifespan in the existing technology for shaft voltage detection and bearing protection.

[0004] To achieve the above objectives, according to one aspect of the present invention, an integrated eddy current sensor is provided, comprising: a housing assembly having a receiving cavity, a portion of the housing assembly being connected to a motor shaft; a PCB board disposed within the receiving cavity; and a resin filling portion filling the receiving cavity to seal the PCB board within the housing assembly; wherein a through-hole structure for the motor shaft to pass through is provided at the center of the housing assembly, the PCB board, and the resin filling portion.

[0005] Furthermore, the housing assembly includes: a housing having a receiving cavity, a first shaft hole through which the motor shaft passes in the middle of the housing; and a mounting wheel connected to the bottom of the housing, the mounting wheel being located outside the receiving cavity, and a second shaft hole in the middle of the mounting wheel having an interference fit with the motor shaft.

[0006] Further, the housing includes: a housing body having a first shaft hole; a first enclosure plate connected to a first surface of the housing body to enclose a receiving cavity; and a second enclosure plate connected to a second surface of the housing body to enclose a receiving space, wherein the first surface and the second surface are disposed opposite to each other, and a mounting wheel is disposed within the receiving space.

[0007] Furthermore, a plurality of conductive brushes are provided on the side of the PCB board away from the mounting wheel. A portion of the conductive brushes forms an inlet brush group and another portion forms an outlet brush group. The inlet brush group is used to apply a preset voltage to the motor shaft, and the outlet brush group is used to draw out the current generated on the motor shaft.

[0008] Furthermore, multiple conductive brushes are arranged at intervals along the circumference of the motor shaft, and the ends of each conductive brush are arranged in contact with the surface of the motor shaft.

[0009] Furthermore, the conductive brushes in the lead-in brush group and the conductive brushes in the lead-out brush group are alternately arranged along the circumference of the motor shaft.

[0010] Furthermore, the PCB board is provided with connectors at its ends, through which the PCB board is electrically connected to external components.

[0011] According to one aspect of the present invention, an electric motor is provided, including an integrated eddy current sensor as described above.

[0012] According to one aspect of the present invention, a method for corrosion protection of a motor shaft is provided. The method includes: acquiring real-time three-phase common-mode voltage information output from the drive board of an inverter; inputting the three-phase common-mode voltage information to a calibration module after EMI filtering to obtain calibrated voltage information; performing nanosecond-level delay calibration on the calibrated voltage information using a dynamic phase compensation network controlled by an FPGA to obtain calibrated voltage information; and, when it is determined that corrosion protection of the motor shaft needs to be performed, amplifying the calibrated voltage information through a power module to obtain a preset value of reverse compensation voltage, and injecting the preset value of reverse compensation voltage into the motor shaft through a set of brushes, wherein, while injecting the preset value of reverse compensation voltage into the motor shaft through the set of brushes, a set of brushes is continuously monitored for the real-time voltage of the motor shaft.

[0013] Furthermore, the calibrated voltage information is amplified by a power module, including a three-stage power amplification of the calibrated voltage information, to solve the problems in the prior art.

[0014] By employing the technical solution of this application, the PCB board is sealed within the housing assembly by filling the cavity with resin filling material. A through-hole structure is provided in the middle of the housing assembly, the PCB board, and the resin filling material, through which the motor shaft passes. The resin filling material not only seals the PCB board but also provides effective insulation between the motor shaft and the sensor, preventing damage to the PCB board from lubricating and cooling liquids. The presence of the through-hole structure allows the sensor to directly contact or approach the motor shaft, improving the detection accuracy of eddy currents and conductive rings for shaft voltage, more effectively protecting the electrode bearings, and extending the motor's service life. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0016] Figure 1 A schematic diagram of the integrated eddy current sensor structure according to a first embodiment of the integrated eddy current sensor according to the present invention is shown.

[0017] Figure 2 A schematic diagram of the installation method of the integrated eddy current sensor and the motor shaft according to a second embodiment of the integrated eddy current sensor according to the present invention is shown.

[0018] Figure 3 A schematic diagram of a method for suppressing the active shaft voltage according to a third embodiment of an integrated eddy current sensor based on the present invention is shown;

[0019] Figure 4 A schematic diagram of a method for eliminating leakage current in an inverter module according to a fourth embodiment of an integrated eddy current sensor based on the present invention is shown.

[0020] The above figures include the following reference numerals:

[0021] 10. Housing assembly; 11. Housing; 12. Mounting wheel; 111. First shaft hole;

[0022] 100. Shell body; 101. Receiving cavity; 102. First enclosure plate; 103. Second enclosure plate; 104. Receiving space;

[0023] 20. PCB board; 21. Connector;

[0024] 30. Resin-filled portion;

[0025] 40. Through-hole structure. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0029] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and therefore their description will be omitted.

[0030] Combination Figures 1 to 4 As shown, according to a specific embodiment of this application, an integrated eddy current sensor is provided.

[0031] The integrated eddy current sensor includes: a housing assembly 10 having a receiving cavity 101, a portion of which is connected to a motor shaft; a PCB board 20 disposed within the receiving cavity 101; and a resin filling portion 30 filling the receiving cavity 101 to seal the PCB board 20 within the housing assembly 10; wherein a through-hole structure 40 for the motor shaft to pass through is provided in the middle of the housing assembly 10, the PCB board 20, and the resin filling portion 30.

[0032] In this embodiment, the PCB board is sealed within the housing assembly by filling the cavity with resin. A through-hole structure is provided in the middle of the housing assembly, the PCB board, and the resin filling, through which the motor shaft passes. The resin filling not only seals the PCB board but also provides effective insulation between the motor shaft and the sensor, preventing damage to the PCB board from lubricating and cooling liquids. The presence of the through-hole structure allows the sensor to directly contact or approach the motor shaft, improving the detection accuracy of eddy currents and conductive rings for shaft voltage, more effectively protecting the electrode bearings, and extending the service life of the motor.

[0033] Specifically, the housing assembly 10 includes: a housing 11 having a receiving cavity 101, and a first shaft hole 111 through which the motor shaft passes in the middle of the housing 11; and a mounting wheel 12 connected to the bottom of the housing 11, located outside the receiving cavity 101, and having a second shaft hole in the middle that is interference-fitted with the motor shaft. Through the separation design of the housing and the mounting wheel, the housing has a receiving cavity and a first shaft hole through which the motor shaft passes, and the mounting wheel is located outside the receiving cavity and connected to the motor shaft through the interference-fitted second shaft hole. This tight physical connection ensures the accuracy of sensor positioning and improves the stability and accuracy of sensor data acquisition.

[0034] Specifically, the housing 11 includes: a housing body 100, on which a first shaft hole 111 is formed; a first enclosure plate 102, which is connected to a first surface of the housing body 100 to form a receiving cavity 101; and a second enclosure plate 103, which is connected to a second surface of the housing body 100 to form a receiving space 104. The first surface and the second surface are arranged opposite to each other, and the mounting wheel 12 is disposed within the receiving space 104. The arrangement of the first and second enclosure plates forms a double enclosure structure. This design places the PCB board and electrical components in a deeper receiving cavity, effectively isolating the electrical and mechanical parts and improving overall safety and reliability.

[0035] In one embodiment of this application, a plurality of conductive brushes 121 are provided on the side of the PCB board 20 away from the mounting wheel 12. A portion of the conductive brushes 121 forms an inlet brush group, and another portion forms an outlet brush group. The inlet brush group is used to apply a preset voltage to the motor shaft, and the outlet brush group is used to draw out the current generated on the motor shaft. By arranging multiple eddy current sensors circumferentially at intervals along the motor shaft, omnidirectional detection of the shaft can be achieved, improving the accuracy of shaft voltage and shaft current detection. The inlet brush group and the outlet brush group are used to apply a preset voltage to the motor shaft and draw out the generated current, respectively. This separate design ensures a clear and reliable current path.

[0036] Furthermore, the conductive brushes 121 in the lead-in brush group and the conductive brushes 121 in the lead-out brush group are alternately arranged along the circumference of the motor shaft. This axially spaced conductive brush design ensures that the current is evenly distributed and collected on the shaft, avoiding current concentration caused by poor local conductive contact and reducing the risk of localized electro-corrosion of the bearings.

[0037] In one embodiment of this application, a connector 21 is provided at the end of the PCB board 20, through which the PCB board 20 is electrically connected to external components. The connector allows for quick and reliable electrical connections, improving assembly efficiency and production speed, while the design of the connector makes PCB board replacement simpler and faster.

[0038] According to another embodiment of this application, a motor is provided, including an integrated eddy current sensor, which is the integrated eddy current sensor described above. By integrating the eddy current sensor with a conductive structure, the shaft current is monitored and derived, and shaft voltage is actively suppressed, optimizing the arrangement space, reducing shaft voltage corrosion of the bearings, and improving the quality of the electric drive.

[0039] According to another embodiment of this application, a method for corrosion protection of a motor shaft is provided. This method is used to protect the motor shaft from corrosion. The method includes: acquiring the real-time three-phase common-mode voltage information output by the inverter's drive board; inputting the three-phase common-mode voltage information to a calibration module after EMI filtering for calibration processing to obtain calibrated voltage information; performing nanosecond-level delay calibration on the calibrated voltage information using a dynamic phase compensation network controlled by an FPGA to obtain calibrated voltage information; when it is determined that corrosion protection of the motor shaft needs to be performed, amplifying the calibrated voltage information through a power module to obtain a preset value of reverse compensation voltage; injecting the preset value of reverse compensation voltage into the motor shaft through a set of brushes; wherein, while injecting the preset value of reverse compensation voltage into the motor shaft through the set of brushes, a set of brushes is continuously monitored for the real-time voltage of the motor shaft. This motor shaft corrosion protection method ensures the real-time performance and accuracy of the corrosion protection strategy by acquiring the three-phase common-mode voltage information output from the inverter drive board in real time. This method can respond instantly to the current voltage conditions, dynamically adjust the reverse compensation voltage, effectively suppress the shaft voltage, and avoid the time delay and insufficient response problems that may occur in passive protection measures. The three-phase common-mode voltage information is processed by EMI filtering, which can significantly reduce electromagnetic interference and ensure that the voltage information received by the calibration module is more accurate and stable. Through the FPGA-controlled dynamic phase compensation network, the voltage information can be calibrated within the nanosecond level, ensuring that the injection of reverse compensation voltage is synchronized with the change of shaft voltage. The calibrated voltage information is amplified by the power module to ensure that a sufficiently strong reverse compensation voltage is injected into the motor shaft. Compared with traditional passive protection measures, this method can more effectively suppress shaft voltage and shaft current, reduce the chance of motor bearing electro-corrosion, extend bearing life, reduce maintenance costs and failure rate. Actively suppressing shaft voltage not only reduces bearing electro-corrosion, but also improves the stability of motor operation, thereby improving the overall performance and reliability of the electric drive system.

[0040] Specifically, the calibrated voltage information is amplified by a power module, including a three-stage power amplification. This three-stage power amplification significantly improves the signal gain, ensuring sufficient strength of the reverse compensation voltage when injected into the shaft, thus achieving effective voltage suppression.

[0041] Specifically, in another embodiment of this application, the active shaft voltage suppression part needs to be implemented in conjunction with the inverter. First, the three-phase common-mode voltage output by the inverter is detected in real time at the inverter's drive board. After EMI filtering, it is input to the calibration module. This module establishes and dynamically updates the shaft voltage transfer function through offline frequency sweep calibration and online pulse response testing. Then, the predicted signal enters the dynamic phase compensation network controlled by the FPGA for nanosecond-level delay calibration. After passing through a three-stage power amplification pre-stage operational amplifier, intermediate frequency broadband amplification, and final stage SiC MOSFET, the reverse compensation voltage is injected into the shaft through contact conductive brushes. At the same time, another set of conductive brushes continuously monitors the actual shaft voltage. The deviation between the actual and predicted values ​​is corrected in real time by the least squares algorithm to adjust the model parameters and fine-tune the phase compensator, forming a complete control loop of "detection-prediction-compensation-feedback".

[0042] Specifically, in another embodiment of this application, the inverter power module generates leakage current, which acts on the stator through the three phases. Based on the magnetic field effect, a circulating current is generated in the bearings at both ends inside the motor. Due to the rapid switching of the inverter, a common-mode voltage Vcom with high du / dt variation will be generated at the motor neutral point to ground. The motor generates a bearing-induced voltage Vb on the motor bearings through parasitic capacitance. Vcom is the motor neutral point voltage to ground, C w For the winding capacitance to the rotor, C WR It is the capacitance from the stator winding to the rotor, C RS It is the capacitance from the rotor to the stator frame, C WS Cb is the capacitance from the stator winding to the stator core; Cb is the inter-bearing capacitance. bDE and C bNDE These are the capacitors of the driving end (DE) and the non-driving end (NDE) bearings, respectively. V ub It is the input reverse suppression voltage, which lowers the potential on both sides of the shaft voltage, thereby suppressing bearing electro-corrosion.

[0043] In one embodiment of this application, the integrated eddy current sensor is installed using a three-point bolt fixation method. The resin primarily serves to cover the PCB board, preventing damage to the PCB board from lubricating and cooling fluids in the electric drive system. The embedded ring 50 supports the fixing bolts. The housing supports the entire sensor assembly. The connector transmits information to the inverter and simultaneously introduces / extracts shaft current to / from the PCB board. The PCB consists of two sides. One side comprises the eddy current sensor, including an eddy current stator, which works in conjunction with the mounting wheel on the motor shaft to detect information such as the shaft's rotation angle and speed. The other side is equipped with two sets of conductive rings formed by conductive fiber brushes. One set of conductive brushes draws the current from the shaft (extraction brush set) and inputs it into the inverter as a detection signal. The other set is responsible for applying the target voltage from the inverter to the shaft (introduction brush set), actively canceling the shaft voltage generated on the shaft.

[0044] Regarding the eddy current sensor, commonly available sensors can be used and will not be discussed further. The shaft voltage suppression requires the inverter. First, the three-phase common-mode voltage output by the inverter is detected in real time at the inverter's driver board. After EMI filtering, it is input to the calibration module. This module establishes and dynamically updates the shaft voltage transfer function through offline frequency sweep calibration and online pulse response testing. Then, the final voltage signal is determined and enters a dynamic phase compensation network controlled by an FPGA for nanosecond-level delay calibration. After three stages of power amplification (pre-amplifier - intermediate frequency broadband amplifier - final stage SiC MOSFET), a reverse compensation voltage is injected into the shaft through contact conductive brushes. Simultaneously, another set of conductive brushes continuously monitors the actual shaft voltage. The deviation between the actual and predicted values ​​is corrected in real time using a least-squares algorithm to adjust the model parameters and fine-tune the phase compensator, forming a complete control loop of "detection-prediction-compensation-feedback".

[0045] The technical solution employing the integrated eddy current sensor and the anti-corrosion method for motor shafts described in this application has the following advantages:

[0046] By detecting the inverter's common-mode voltage in real time and dynamically generating a reverse compensation signal, which is then amplified at high speed and precisely injected into the motor shaft, the shaft voltage is actively offset, effectively suppressing bearing current and protecting the motor bearing from electro-corrosion damage.

[0047] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, rotated 90 degrees, or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0048] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0049] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0050] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for corrosion protection of a motor shaft, characterized in that, The motor includes an integrated eddy current sensor and a motor shaft. The integrated eddy current sensor includes: A housing assembly (10) having a receiving cavity (101), a portion of the housing assembly (10) being connected to a motor shaft; PCB board (20), the PCB board (20) is disposed in the receiving cavity (101); A resin filling portion (30) is filled into the receiving cavity (101) to seal the PCB board (20) within the housing assembly (10); The housing assembly (10), the PCB board (20) and the resin filling part (30) are provided with a through hole structure (40) for the motor shaft to pass through. The housing assembly (10) includes: The housing (11) has the receiving cavity (101) and a first shaft hole (111) for the motor shaft to pass through is provided in the middle of the housing (11). Mounting wheel (12) is connected to the bottom of housing (11). The mounting wheel (12) is located outside the receiving cavity (101). The mounting wheel (12) has a second shaft hole in the middle that is interference fit with the motor shaft. The PCB board (20) is provided with a plurality of conductive brushes (121) on the side away from the mounting wheel (12). A portion of the plurality of conductive brushes (121) forms an inlet group brush and another portion forms an outlet group brush. The inlet group brush is used to apply a preset voltage to the motor shaft, and the outlet group brush is used to draw out the current generated on the motor shaft. The corrosion resistance method is used to resist corrosion of the motor shaft. The motor shaft corrosion resistance method includes: acquiring the three-phase common-mode voltage information output in real time by the inverter's drive terminal board; The three-phase common-mode voltage information is filtered by EMI and then input to the calibration module for calibration processing to obtain the calibrated voltage information. The calibrated voltage information is subjected to nanosecond-level delay calibration by a dynamic phase compensation network controlled by an FPGA to obtain calibrated voltage information. When it is determined that anti-corrosion work needs to be performed on the motor shaft, the calibrated voltage information is amplified by the power module to obtain a reverse compensation voltage of a preset value. The reverse compensation voltage of the preset value is injected into the motor shaft through the introduced brush group. At the same time as the reverse compensation voltage of the preset value is injected into the motor shaft through the introduced brush group, the led-out brush group continuously monitors the real-time voltage of the motor shaft.

2. The method for corrosion protection of motor shafts according to claim 1, characterized in that, The housing (11) includes: The housing body (100) has the first shaft hole (111) provided on it. A first enclosure (102) is connected to the first surface of the housing body (100) to form the receiving cavity (101). The second enclosure (103) is connected to the second surface of the housing body (100) to form an accommodating space (104), the first surface and the second surface are disposed opposite each other, and the mounting wheel (12) is disposed in the accommodating space (104).

3. The method for corrosion protection of motor shafts according to claim 1, characterized in that, The plurality of conductive brushes (121) are arranged at intervals along the circumference of the motor shaft, and the end of each conductive brush (121) is arranged in contact with the surface of the motor shaft.

4. The method for corrosion protection of motor shafts according to claim 1, characterized in that, The conductive brushes (121) in the inlet brush group and the conductive brushes (121) in the outlet brush group are alternately arranged along the circumference of the motor shaft.

5. The method for corrosion protection of motor shafts according to claim 1, characterized in that, The PCB board (20) is provided with a connector (21) at its end, and the PCB board (20) is electrically connected to external components through the connector (21).

6. The method for corrosion protection of motor shafts according to claim 1, characterized in that, The calibrated voltage information is amplified by a power module, including a three-stage power amplification process.

7. An electric motor, wherein the electric motor performs the method for corrosion protection of the motor shaft according to any one of claims 1 to 6.

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