Eddy current sensor, detection device and electric driving system

Abstract

The invention provides an eddy current sensor, a detection device and an electric driving system, and the sensor comprises an eddy current rotor, one end of which is connected with a rotating shaft of a to-be-detected motor and rotates synchronously; one end of the printed circuit board assembly is an electromagnetic induction area, the exciting coil and the receiving coil are arranged in the electromagnetic induction area, the receiving coil is distributed on the inner side of the exciting coil, the other end of the eddy current rotor is close to the electromagnetic induction area to form a preset air gap distance, and the eddy current control module is arranged at the other end of the printed circuit board assembly. The eddy current control module is connected with the excitation coil to form a high-frequency oscillation magnetic field and is connected with the receiving coil to receive the induced electromotive force. The design is compact, the size is greatly reduced, light weight is achieved, and the installation space and the manufacturing cost are reduced.

Description

Technical Field

[0001] The present application relates to the technical field of electronic components, and in particular to an eddy current sensor, a detection device, and an electric drive system. Background Art

[0002] The speed range of mainstream new energy vehicle drive motors on the market is within 16,000 RPM (revolutions per minute), and rotary transformers are generally used as angle position signal sensors to detect the relative position of the stator and rotor. However, with the rise of high-voltage platforms, the speed requirements for motors are more stringent, and the maximum speed even exceeds 20,000 RPM.

[0003] However, in the relevant technologies, the use of rotary transformers can no longer meet the requirements of suppliers and end customers for high-precision detection of rotor position, mainly in the following aspects:

[0004] First, the excitation signal frequency of the resolver is 10kHz. When the speed exceeds 20,000RPM, the number of fundamental waves of the resolver signal collected is insufficient. Compared with the number of fundamental waves collected at 5,000RPM, it is less than a quarter. There is a large error between the fitted angle signal curve and the actual angle, which affects the torque accuracy of the motor.

[0005] Second, the angular accuracy level is limited. Currently, most rotary transformers require the angular accuracy to be ±33'mech (4 pairs of poles), which cannot meet the sensor's high-precision level of ±22.5'mech (4 pairs of poles).

[0006] Third, the magnetic field of the high-speed motor and the switch of the electronically controlled IGBT will cause EMC interference to the angle sensor signal transmission path. The rotating transformer excitation frequency is 10kHz, which is consistent with the IGBT switching frequency. The switching of the IGBT is likely to affect the original carrier transmitted by the sensor, causing the demodulated signal to be distorted, resulting in a decrease in the accuracy of the angle signal.

[0007] Fourth, the raw materials of the rotating transformer itself are expensive, the process route is complicated, and the complex processes involved in the manufacturing process, such as winding and welding, make it difficult to reduce costs. Summary of the invention

[0008] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide an eddy current sensor, a detection device and an electric drive system to solve at least one of the above-mentioned technical problems.

[0009] To achieve the above-mentioned purpose and other related purposes, the first aspect of the present application provides an eddy current sensor, comprising: an eddy current rotor, an excitation coil, a receiving coil, an eddy current control module and a printed circuit board assembly; the eddy current rotor, one end of which is connected to the rotating shaft of the motor to be measured and rotates synchronously; one end of the printed circuit board assembly is an electromagnetic induction area, the excitation coil and the receiving coil are insert-molded in the electromagnetic induction area, and the receiving coil is distributed on the inner side of the excitation coil, the other end of the eddy current rotor is close to the electromagnetic induction area to form a preset air gap spacing, the eddy current control module is arranged at the other end of the printed circuit board assembly, the eddy current control module is connected to the excitation coil to form a high-frequency oscillating magnetic field, and the eddy current control module is connected to the receiving coil to receive the induced electromotive force.

[0010] In some embodiments of the first aspect of the present application, the printed circuit board assembly is at least two layers of boards, each layer of boards is provided with a complete period of excitation coils and receiving coils, wherein the excitation coil is in a closed ring shape, and the receiving coil is distributed in the closed ring winding.

[0011] In some embodiments of the first aspect of the present application, the receiving coil includes a sine winding and a cosine winding that are orthogonally distributed, so as to obtain a sine-cosine envelope signal.

[0012] In some embodiments of the first aspect of the present application, the structure of the electromagnetic induction zone includes at least one of an annular structure, a circular structure or a semicircular structure.

[0013] In some embodiments of the first aspect of the present application, the eddy current sensor further includes a housing assembly for accommodating the printed circuit board assembly, and assembling the printed circuit board assembly in the housing assembly.

[0014] In some embodiments of the first aspect of the present application, the shape of the housing assembly matches the shape of the printed circuit board assembly, and an output port of the eddy current sensor is provided at one end close to the eddy current control module.

[0015] In some embodiments of the first aspect of the present application, the output port of the eddy current sensor is a connector, and the connector is externally connected to a wiring harness component in a linked form.

[0016] In some embodiments of the first aspect of the present application, if the electromagnetic induction area is an annular structure and the housing component is provided with a through hole, the center of the annular structure is mounted on the through hole to assemble the printed circuit board assembly.

[0017] In some embodiments of the first aspect of the present application, the other end of the eddy current rotor passes through the through-hole member to form a preset air gap distance.

[0018] In some embodiments of the first aspect of the present application, the method further includes: a potting compound for sealing the printed circuit board assembly in the housing assembly.

[0019] In some embodiments of the first aspect of the present application, a coil diameter formed by the excitation coil and the receiving coil is less than or equal to 30 mm.

[0020] In some embodiments of the first aspect of the present application, the outer wall of the housing component is provided with symmetrically distributed limiting fixing holes.

[0021] In some embodiments of the first aspect of the present application, the printed circuit board assembly is made using a PCBA plate making process.

[0022] In some embodiments of the first aspect of the present application, the eddy current control module includes an eddy current chip, an excitation circuit and a receiving circuit. The eddy current chip controls the excitation coil through the excitation circuit to excite a high-frequency oscillating magnetic field. The eddy current chip receives the orthogonal high-frequency signal through the receiving circuit and the receiving coil for demodulation, and outputs a sine and cosine envelope signal.

[0023] A second aspect of the present application provides an angular position detection device, comprising the above-mentioned eddy current sensor, for detecting the magnitude and phase of the induced current to determine the angular position of the rotor of the motor to be measured.

[0024] A third aspect of the present application provides an electric drive system, comprising the above-mentioned eddy current sensor; or / and the above-mentioned angular position detection device.

[0025] As described above, a technical solution of the eddy current sensor, detection device and electric drive system described in the present application has the following beneficial effects:

[0026] The present application integrates an excitation coil, a receiving coil and an eddy current control module in a printed circuit board assembly corresponding to the eddy current sensor, wherein the excitation coil and the receiving coil are integrated in the electromagnetic induction area of ​​the printed circuit board assembly by means of injection molding inserts. On the one hand, the overall design is compact, which greatly reduces the volume and achieves lightweight, and is easy to integrate into various devices, reducing the installation space while reducing the manufacturing cost; on the other hand, since the high-frequency oscillating magnetic field can respond quickly to the rotation of the rotor, the receiving coil captures the changes in the induced electromotive force in real time, so that the eddy current sensor has a faster dynamic response speed; at the same time, based on the interaction between the high-frequency oscillating magnetic field and the rotating rotor, the received induced electromotive force is accurately measured to reflect parameters such as speed or displacement, so that the single eddy current sensor can achieve high-precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1Shown is a structural schematic diagram of an eddy current sensor provided by the present application;

[0028] Figure 2 Shown is a schematic diagram of an exploded structure of an eddy current sensor provided by the present application from a first-person perspective;

[0029] Figure 3 Shown is a schematic diagram of an exploded structure of an eddy current sensor provided by the present application from a second perspective;

[0030] Figure 4 Shown is a schematic diagram of an eddy current sensor assembly provided by the present application;

[0031] Figure 5 Shown is a schematic diagram of an electromagnetic induction area in an eddy current sensor provided by the present application;

[0032] Figure 6 Shown is a schematic diagram of the principle of a four-pole motor rotor position sensor provided by the present application;

[0033] Figure 7 Shown is a control system structure diagram of an eddy current sensor provided by the present application;

[0034] Figure 8 A schematic diagram showing an electromagnetic induction area of ​​a semicircular structure provided by the present application;

[0035] Fig. 9 A schematic diagram showing an electromagnetic induction zone of a ring structure provided by the present application;

[0036] Fig.10 Shown is a schematic structural diagram of a conventional arc-shaped eddy current sensor provided by the present application;

[0037] Fig.11 Shown is a structural schematic diagram of an arc-shaped eddy current sensor provided by the present application;

[0038] Fig.12 Shown is a traditional wiring harness connection solution for an eddy current sensor provided by the present application;

[0039] Fig.13 Shown is a new wiring harness connection solution for eddy current sensors provided by the present application.

[0040] Description of reference numerals:

[0041] 1. Eddy current rotor, 2. Printed circuit board assembly, 21. Excitation coil, 22. Receiving coil, 23. Eddy current control module, 3. Shell assembly, 4. Potting glue. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0043] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application, and thus the drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0044] In the development of related technologies, there are many sensor solutions developed for high precision. In current designs, TMR magnetic sensors and grating sensors are widely used.

[0045] Eddy current sensor is a non-contact sensor widely used in industrial automation, robotics, aerospace and other fields. It is used to detect defects on the surface of conductors and measure parameters such as the position, speed and density of conductors. However, the traditional eddy current sensor has a large volume, high cost and high overall weight due to the coil arrangement design. At the same time, the welding scheme adopted cannot be flexibly deformed. Once it involves different needs of different customers for the wiring harness, it needs to be redeveloped as a whole. The structural design is inflexible and not conducive to expansion. In addition, since the coil design uses a complete four-layer board to complete the drawing of two receiving coils, for example, the middle two layers of distributed receiving coils are used, resulting in low acquisition accuracy and inability to achieve high-precision requirements.

[0046] For example, the TMR magnetic sensor, i.e. the magnetoresistive angle sensor, mainly includes a magnet and a chip. As the magnet at the end of the motor rotor rotates, the corresponding angle information can be sensed by using the characteristic that the resistance of the semiconductor inside the chip changes with the direction of the external magnetic field. However, the cost of the TMR magnetic sensor itself is relatively high (including the magnet + packaged sensor), which is not conducive to the cost control of the whole machine. At the same time, the TMR magnetic sensor is sensitive to changes in the temperature field and there is a risk of demagnetization.

[0047] For example, grating sensors are sensors that use the principle of grating fringe stripes to measure displacement. The grating is a dense and equally spaced parallel engraved line on a long strip of optical glass, with a line density of 10 to 100 lines per millimeter. The grating fringe stripes formed by the grating have optical amplification and error averaging effects, thereby improving measurement accuracy. However, high-precision grating sensors are expensive, have poor environmental adaptability, and are not oil-resistant. Therefore, they are not conducive to the structural design of the bridge assembly and product cost reduction.

[0048] To sum up, for suppliers and end customers, the eddy current sensors in the existing technology have the disadvantages of high cost, large size, low accuracy and poor expansibility. There is an urgent need for a sensor with high detection accuracy, low manufacturing cost and strong environmental adaptability to detect the rotor position.

[0049] See also Figure 1 , is a schematic diagram of the structure of an eddy current sensor provided by this application, which is described in detail as follows:

[0050] Eddy current rotor 1, exciting coil 21, receiving coil 22, eddy current control module and printed circuit board assembly 2;

[0051] The eddy current rotor 1 has one end connected to the shaft of the motor to be tested and rotates synchronously;

[0052] For example, the air gap spacing refers to the gap between the upper surface of the eddy current sensor rotor and the lower end surface of the eddy current sensor stator. Here, if the current shell component has a through hole, then the lower end surface of the stator is the inner wall of the through hole; if there is no shell component, then the lower end surface of the stator is the electromagnetic induction area, wherein the air gap spacing is related to the size and accuracy of the output signal, and at the same time, indirectly affects the motor speed control, output power and efficiency, etc.

[0053] One end of the printed circuit board assembly 2 is an electromagnetic induction zone, and the excitation coil 21 and the receiving coil 22 are arranged in the electromagnetic induction zone, wherein the arrangement method includes but is not limited to insert injection molding, electrochemical corrosion, 3D printing, machine winding, printed inductance technology, surface mounting technology, etc., and the receiving coil 22 is distributed on the inner side of the excitation coil 21, and the other end of the eddy current rotor 1 is close to the electromagnetic induction zone to form a preset air gap spacing, and the eddy current control module is arranged at the other end of the printed circuit board assembly 2, and the eddy current control module is connected to the excitation coil 21 to form a high-frequency oscillation magnetic field, and the eddy current control module is connected to the receiving coil 22 to receive the induced electromotive force;

[0054] Specifically, the printed circuit board assembly is at least two layers of boards, each layer of boards is provided with a complete cycle of excitation coils and receiving coils, wherein the excitation coil is in a closed ring shape, the receiving coil is wound in the closed ring shape, the excitation coil and the receiving coil are not connected to each other (not connected), and are both connected to the eddy current control module, such as Figure 6 As shown, the sine winding and the cosine winding in the receiving coil are respectively connected to the eddy current control module through corresponding annular buckles.

[0055] Among them, it should be understood that the structure of the electromagnetic induction zone includes at least one of an annular structure, a circular structure or a semicircular structure. The annular structure is taken as an example for explanation herein. The annular structure includes an intersecting area (i.e., a ring) formed by a large circle and a small circle with the same center. The center area where the center of the circle is located is a hollow circular hole, which is matched with the through hole of the outer shell component 3 through the circular hole, that is, the through hole is passed through the through hole and assembled in the outer shell component 3 by a snap-fit ​​manner.

[0056] It should also be noted that the electromagnetic induction zone refers to the phenomenon that when the conductor (i.e. one end of the rotor) moves in a magnetic field to cut the magnetic flux lines, an electric current is generated in the conductor. The electromagnetic induction zone includes an electromagnetic field composed of an excitation coil and a receiving coil.

[0057] Optionally, if the eddy current sensor further includes a housing assembly, the housing assembly 3 is used to accommodate the printed circuit board assembly, and the printed circuit board assembly is assembled in the housing assembly; of course, the eddy current sensor may also not include a housing assembly, which is not elaborated here.

[0058] The eddy current rotor 1 rotates in the high-frequency oscillating magnetic field, and forms eddy currents on the surface of the eddy current rotor. The reverse magnetic field generated by the eddy currents is used to weaken the high-frequency oscillating magnetic field so that the induced electromotive force generates an induced current.

[0059] Optionally, if the structure of the magnetic induction zone is an annular structure, a through hole is provided in the shell component, and the center of the annular structure is mounted on the through hole to assemble the printed circuit board assembly, and the shell component 3 is used to accommodate the printed circuit board assembly 2, and the electromagnetic induction zone is assembled on the through hole; at the same time, the other end of the eddy current rotor 1 passes through the through hole to form a preset air gap spacing.

[0060] It should be noted that the inner wall of the through hole of the shell component 3 is smooth, which facilitates the free rotation of the eddy current rotor in the through hole while maintaining a preset air gap spacing. At the same time, the outer wall of the through hole assembled with the electromagnetic induction zone matches the circular hole of the electromagnetic induction zone, for example, the shape and size are basically consistent, and a plurality of arc-shaped patches are provided on the outer wall of the through hole, and the arc-shaped patches press the printed circuit board assembly 2 against the through hole (base or mounting plate) presented by the shell component through a hot riveting process.

[0061] It should also be noted that when the motor shaft drives the eddy current rotor to rotate, it will continuously cut the high-frequency oscillating magnetic field generated by the excitation coil. Through the cutting, an induced electromotive force will be received in the receiving coil. The size of the induced electromotive force is related to factors such as the rotor speed, air gap spacing and magnetic field strength. The eddy current control module receives and processes the induced electromotive force signal, and finally outputs measurement data related to the motion state of the motor shaft.

[0062] In some embodiments, the printed circuit board assembly is at least two layers of boards, and each layer of boards is provided with a complete period of excitation coils and receiving coils, wherein the excitation coil is a closed ring, and the receiving coil is distributed in the closed ring, and the receiving coil includes orthogonally distributed sine windings and cosine windings for obtaining sine and cosine envelope signals.

[0063] For example, in order to ensure the accuracy of the eddy current sensor, the printed circuit board assembly is a four-layer board, and each layer is provided with a complete cycle of excitation coils and receiving coils, wherein the excitation coil is a closed ring, and the receiving coil is wound in the closed ring. Of course, if the manufacturing cost is not considered, a design with more layers can also be used, for example, a five-layer board, a six-layer board, a seven-layer board, an eight-layer board, etc.

[0064] Specifically, the design structure of the eddy current sensor is composed of a potting glue 4, a printed circuit board assembly 2 (PCBA), a housing assembly 3 and an eddy current rotor 1. For example, the PCBA is a four-layer board design, on which an excitation coil and a receiving coil are arranged, and the rotor is assembled with the motor shaft. The eddy current chip carried on the PCBA can control the excitation coil to excite a high-frequency oscillating magnetic field of 2 to 5Mhz, and the sine and cosine receiving coils arranged orthogonally at 90° generate an induced electromotive force of high-frequency oscillation due to electromagnetic induction. The eddy current rotor (non-magnetic metal target wheel) at a certain air gap distance from the eddy current sensor will generate induced eddy currents, thereby weakening the magnetic field of the excitation coil. As the target wheel rotates, the induced electromotive force of the receiving coil changes with the area covered by the target wheel, and the orthogonal high-frequency signal is input into the chip through the receiving coil, and the high-frequency demodulation work is completed by the eddy current chip, and the demodulated sine and cosine envelope signals will be input into the MCU of the electronic control for the calculation of the angle signal.

[0065] In this embodiment, the arc scheme cannot draw the receiving coil in a single-layer board of the PCB according to a complete cycle. The drawing of two receiving coils is completed by adopting a four-layer board with a complete cycle. For example, in the designed coil PCB scheme, each layer of the four-layer board completes the arrangement of the receiving coil in a complete cycle, so that the received eddy current signal strength is higher than that of the traditional arc scheme, the axial position installation redundancy is large, and it is easy to install.

[0066] In this embodiment, the eddy current sensor adopts a highly integrated design solution, integrating the eddy current control module with the PCBA, and using eddy current sensing technology to sense the eddy current changes of the matching target wheel during rotation. The received high-frequency signal is then decoded in real time through the eddy current chip, and the sine and cosine envelope analog signal with the high-frequency carrier signal removed can be obtained and input into the MCU in real time, ensuring high-precision and low latency (4us propagation delay) of the angle feedback under high-speed conditions.

[0067] Through the above method, the excitation coil, the receiving coil and the eddy current control module are integrated in the printed circuit board assembly corresponding to the eddy current sensor, wherein the excitation coil and the receiving coil are integrated in the electromagnetic induction area of ​​the printed circuit board assembly by injection molding inserts. On the one hand, the overall design is compact, which greatly reduces the volume and achieves lightweight, and is easy to integrate into various devices, reducing the installation space while reducing the manufacturing cost; on the other hand, since the high-frequency oscillating magnetic field can quickly respond to the rotation of the rotor, the receiving coil captures the changes in the induced electromotive force in real time, so that the eddy current sensor has a faster dynamic response speed; at the same time, based on the interaction between the high-frequency oscillating magnetic field and the rotating rotor, the received induced electromotive force is accurately measured to reflect parameters such as speed or displacement, so that the single sensor of the eddy current sensor can achieve high precision requirements.

[0068] Optionally, see Figure 2 , showing a schematic diagram of the exploded structure of an eddy current sensor provided by the present application from a first-person perspective, please refer to Figure 3 , is a schematic diagram of the exploded structure of an eddy current sensor provided by the present application from a second perspective, including:

[0069] like Figure 2 As shown in FIG. 1 , the yellow portion of the printed circuit board assembly 2 is an electromagnetic induction zone, in which the excitation coil and the receiving coil are respectively arranged from the inside to the outside by injection molding embedding, and an eddy current control module is arranged on the other side of the lower part of the printed circuit board assembly, and the pins of the eddy current control module are connected to the output port of the eddy current sensor, as shown in FIG. Figure 3 As shown, the green-painted portion of the printed circuit board assembly 2 is a printed circuit board assembly, which includes an electromagnetic induction receiving coil, and an eddy current control module is provided at the lower portion of the corresponding printed circuit board assembly 2 on this side.

[0070] Optionally, the shape of the housing assembly matches the shape of the printed circuit board assembly, and an output port of the eddy current sensor is provided at one end close to the eddy current control module.

[0071] Among them, the shape of the housing assembly matches the shape of the printed circuit board assembly, which is not only conducive to protecting the printed circuit board assembly from physical damage, but also ensures the precise alignment and fixation between the components inside the sensor; at the same time, the shape matching not only reduces the risk of loosening or damage of internal components due to vibration or impact, improves the reliability and durability of the sensor, but also helps to stabilize the PCBA using the hot riveting process.

[0072] In addition, setting the output port at one end close to the eddy current control module not only shortens the signal transmission path and reduces signal attenuation and interference; it also reduces PCBA wiring costs by connecting with external devices or systems at the output port.

[0073] Among them, the output port of the eddy current sensor is a connector, and the connector is connected to the external wiring harness assembly in a linked form. The connector is used as the output port in the eddy current sensor, which is convenient for connecting and disconnecting with the external wiring harness assembly without welding or special tools, reducing the difficulty and cost of installation and maintenance.

[0074] In addition, the connector also provides dual electrical and mechanical protection to prevent signal interruption or equipment damage caused by poor connection or external force impact. The above interface design is conducive to widespread replication and promotion on existing product structures.

[0075] Optionally, see Figure 4 , which is a schematic diagram of an eddy current sensor assembly provided in the present application; it also includes: a potting glue, which is used to seal the printed circuit board assembly in the housing assembly.

[0076] Among them, potting compound is an adhesive used to seal, fix and protect electronic components and circuits. In the manufacturing process of eddy current sensors, potting compound is used to firmly seal the printed circuit board assembly (including various electronic components and connecting wires on the circuit board) inside the shell assembly. It should be noted that the potting compound is epoxy resin glue.

[0077] In the above embodiments, different packaging designs can be used to adapt to oil-cooled / water-cooled electric drive designs; at the same time, the electric drive cost can also be effectively reduced.

[0078] Optionally, the PCBA plate-making process is used to change the layer board design to a two-layer board, so that the production cost of raw materials can be reduced. Specifically, the PCBA plate-making process reduces parameters such as line width / line spacing to achieve the purpose of cost saving.

[0079] For example, Number of copper layers is 4; PCB Base material Final is FR-4; PCB Thickness is 1.60mm+ / -10%; Thickness of coppercoating is 35um; Final cover is ENIG; Minimal copper width is 0.1mm; Minimal copper to copper distance is 0.2mm; Via hole / pad diameter is 0.2 / 0.4mm; Slotted holes, No; Panelsize is 46.50x29.6mm; Silk screen color is White on TOP, and Soldermask color is White on TOP.

[0080] In this embodiment, the manufacturing cost is further reduced by optimizing the layer design and PCBA plate making process.

[0081] from Figures 1 to 4 It can be seen that the outer wall of the shell component is provided with symmetrically distributed limiting fixing holes for installing or fixing other components. At the same time, it is ensured that the components can maintain a stable position after installation. The above-mentioned limiting fixing holes are often distributed in a symmetrical manner to enhance the stability and balance of the structure.

[0082] For example, the housing assembly includes multiple symmetrically distributed limit fixing holes for fixing the installation interface. The precise arrangement and symmetrical distribution of the limit fixing holes can ensure that the mechanical components maintain the correct relative position during operation, reduce vibration and wear, and improve the overall performance and life of the equipment.

[0083] Optionally, see Figure 5 , is a schematic diagram of an electromagnetic induction area in an eddy current sensor provided in the present application, wherein the receiving coil includes a sine winding and a cosine winding that are orthogonally distributed, and is used to obtain sine and cosine envelope signals.

[0084] Among them, the sine winding and cosine winding are orthogonally distributed in physical space, that is, their magnetic induction lines or current paths are perpendicular to each other in space. Through the orthogonal distribution of the sine winding and cosine winding, two induced electromotive force signals of different phases can be obtained at the same time. These two induced electromotive force signals are usually in the form of sine waves and cosine waves, and their phase difference is 90 degrees (or π / 2 radians). Through this layout, the two sets of windings can respectively sense the changes in the magnetic field in different directions, thereby improving the accuracy and stability of position detection.

[0085] Specifically, when an external magnetic field (such as a rotating magnetic field, an alternating magnetic field, etc.) acts on the receiving coil, the sine winding and the cosine winding will respectively generate induced electromotive force. Due to their different spatial layouts, the waveform and phase of the induced electromotive force will also be different.

[0086] In addition, during the signal processing stage, the eddy current control module extracts the sine and cosine envelope signals from the two induced electromotive force signals through phase-sensitive detection, demodulation and other technical means. The envelope signal contains key information such as the amplitude, frequency and phase of the external magnetic field change, so that the MCU can subsequently solve it with an angle signal.

[0087] In the above manner, the orthogonal distribution of the sine winding and cosine winding in the receiving coil is an efficient and practical design method, which obtains the sine and cosine envelope signals through the induction principle, providing important technical support for the fields of motor control, position detection, etc.

[0088] See also Figure 6 , is a schematic diagram of the principle of a four-pole motor rotor position sensor provided in this application;

[0089] Among them, four pairs of poles usually refer to four pairs of N poles and S poles, and generally refer to sensors. In angle verification sensors, four pairs of poles are equivalent to dividing a mechanical cycle into four electrical cycles to evaluate accuracy. In this type of motor, the role of the rotor position sensor is to detect the exact position of the rotor and transmit this information to the control system so that the control system can accurately control the operation of the motor.

[0090] Specifically, the design structure of the eddy current sensor consists of potting glue, PCBA, shell assembly and eddy current rotor. PCBA is a four-layer board design, on which the excitation coil and the receiving coil are arranged, and the rotor is assembled with the motor shaft. The eddy current chip carried on the PCBA can control the excitation coil to excite a high-frequency oscillating magnetic field of 2 to 5Mhz. The sine and cosine receiving coils arranged orthogonally at 90° generate an induced electromotive force of high-frequency oscillation due to electromagnetic induction. The eddy current rotor (non-magnetic metal target wheel) at a certain air gap distance from the eddy current sensor will generate induced eddy currents, thereby weakening the magnetic field of the excitation coil. As the target wheel rotates, the induced electromotive force of the receiving coil changes with the area covered by the target wheel. The orthogonal high-frequency signal is input into the chip through the receiving coil, and the high-frequency demodulation work is completed by the eddy current chip. The demodulated sine and cosine envelope signals will be input into the electronic control MCU for angle signal resolution. For example, the sine and cosine envelope analog signals are obtained by removing the high-frequency carrier signal and input into the MCU in real time, which improves the high precision and low latency (4us propagation delay) of the eddy current sensor angle feedback while achieving high speed.

[0091] In the above way, when a high-frequency current is passed through the excitation coil in the eddy current sensor, a high-frequency alternating magnetic field will be generated around it. When the metal conductor under test is close to this magnetic field, eddy currents, i.e. eddy currents, will be induced in the metal conductor. Since eddy currents will generate a magnetic field in the opposite direction to the excitation magnetic field, called a reverse magnetic field, the reverse magnetic field will change the inductance of the excitation coil and thus change its impedance. By measuring the change in the impedance, the distance, speed, displacement and other parameters between the metal conductor under test and the sensor can be inferred.

[0092] See also Figure 7 , is a control system structure diagram of an eddy current sensor provided in this application, which is described in detail as follows:

[0093] Optionally, through chip selection and coil design, the eddy current sensor can meet the application of motor angle position detection up to 150000RPM.

[0094] Specifically, in order to detect the angular position of such a high-speed motor, the sensor chip needs to have an extremely high frequency response capability, for example, the chip is required to be able to process high-frequency signals and quickly and accurately convert them into measurable electrical signals. In a high-speed rotating motor, even small changes in the angular position need to be accurately captured. Therefore, the chip needs to have high-precision measurement capabilities and long-term stability to ensure the accuracy of the measurement results.

[0095] In addition, in order to accurately detect the angular position in a high-speed rotating motor, it is necessary to optimize the magnetic field distribution of the coil to ensure that the magnetic field can evenly and stably cover the measured area. For example, an electromagnetic induction area with a ring structure is adopted. For example, the sine and cosine receiving coils arranged orthogonally at 90° generate an induced electromotive force with high-frequency oscillation due to electromagnetic induction, which can improve its ability to receive eddy current electrical signals; by optimizing the structure and material of the coil, the sensitivity of the sensor is improved, so that it can more accurately capture changes in the angular position of the motor.

[0096] In addition, coil design needs to consider how to reduce the impact of these noise interferences on the measurement results, such as by using shielding technology or optimizing circuit layout to reduce electromagnetic interference.

[0097] As shown in Figure 7, a rotary transformer is used as an angle position signal sensor to detect the relative position of the stator and rotor. A complex excitation circuit and a low-latency decoder are required between the rotary transformer and the MCU. This not only increases the hardware cost of the control system to a certain extent, but also makes the angle position calculation logic of the motor rotor to be measured more complicated.

[0098] However, the present application does not require complex excitation circuits (RDC), filtering circuits, and low-latency eddy current chips. The receiving coils of the cosine winding and the sine winding generate an induced electromotive force of high-frequency oscillation due to electromagnetic induction. The induced electromotive force of the receiving coil changes with the area covered by the target wheel. The orthogonal high-frequency signal is input into the chip through the receiving coil, and the high-frequency demodulation is completed by the eddy current chip. The demodulated sine and cosine envelope signals are input into the electronic control MCU for angle signal resolution. Compared with the rotary transformer, it not only reduces the cost, volume and weight, but also has the ability to detect the motor angle position up to 150,000 RPM.

[0099] Optionally, the eddy current control module includes an eddy current chip, an excitation circuit and a receiving circuit. The eddy current chip controls the excitation coil through the excitation circuit to excite a high-frequency oscillating magnetic field of 2 to 5 MHz. The eddy current chip receives the orthogonal high-frequency signal through the receiving circuit and the receiving coil for demodulation, and outputs a sine and cosine envelope signal.

[0100] Specifically, the eddy current chip is responsible for controlling the excitation circuit to generate a high-frequency oscillating magnetic field and processing the orthogonal high-frequency signal from the receiving circuit; the eddy current chip integrates a complex digital signal processor (DSP) or microcontroller (MCU) and analog front-end circuit for signal generation, reception, processing and demodulation.

[0101] For example, under the control of the eddy current chip, the excitation circuit provides electrical energy to the excitation coil, enabling it to excite a high-frequency oscillating magnetic field of 2 to 5 MHz. When a metal conductor approaches the excitation coil, eddy currents are generated on its surface, which in turn change the impedance of the excitation coil or generate an induced voltage. This impedance change is used to detect the position, speed or other related parameters of the metal conductor.

[0102] For example, the receiving circuit is connected to the receiving coil to capture the orthogonal high-frequency signal caused by the induced voltage or impedance change generated by the metal conductor. The orthogonal high-frequency signal is usually very weak and superimposed on the high-frequency oscillating magnetic field. Therefore, it is necessary to extract useful information through filtering, amplification and other processing methods.

[0103] In this embodiment, in the eddy current sensor, in order to obtain higher measurement accuracy and stability, orthogonal demodulation technology is used to process the received high-frequency signal. Orthogonal demodulation is a method of decomposing a high-frequency signal into two orthogonal components (usually sine and cosine components). By processing these two components separately, noise and interference in the signal can be eliminated and the signal-to-noise ratio of the signal can be improved. The eddy current chip demodulates the orthogonal high-frequency signal received by the receiving circuit and finally outputs a sine-cosine envelope signal, which contains information on parameters such as the position and speed of the metal conductor, and can be further processed or converted into a digital signal for display, recording or control, which will not be repeated here.

[0104] Through the above methods, the BOM (Bill of Materials) cost of the eddy current sensor is transparent and the production process is simple; the key process SMT (Surface Mount Technology) + electrical testing can be highly automated, reducing manpower input, and can effectively reduce the electronic control cost of the motor + electronic control. The transparent material cost of the eddy current sensor, coupled with its simple process flow, can achieve cost reduction at the component level. In addition, since the eddy current sensor has a built-in eddy current chip, the demodulation circuit of the original electronic control level resolver signal can be optimized and removed, which can also achieve electronic control cost reduction.

[0105] See also Figure 8 , which is a schematic diagram of an electromagnetic induction area of ​​a semicircular structure provided in the present application; wherein, the semicircular scheme corresponding to the semicircular structure only uses an area of ​​1 / 2 circle for coil arrangement, and cannot form a complete cycle. The recognition signal error is higher than that of the full-circle scheme. If a semicircular scheme is to be adopted, compensation can be performed through software and hardware. For example, after using hardware RC filtering, software is used to perform waveform correction and amplitude compensation on the analog signal, which can be used in different customer scenarios.

[0106] See also Fig. 9, is a schematic diagram of an electromagnetic induction zone of a ring structure provided in this application, which is described in detail as follows:

[0107] like Fig. 9 As shown in the figure, the center of the electromagnetic induction area of ​​the ring structure is solid (i.e., there is no hollow area), and it is used as a full-circle solution. The coils of the full-circle solution can be arranged in a complete cycle, and the induced eddy current can cover the entire circle, so the signal integrity of the recognition is high. In addition, due to the periodic integrity of the full-circle coil solution, periodic compensation can be performed during the rotor rotation process of the offline test, and it has a strong ability to resist radial errors caused by installation. Therefore, the full-circle design solution can have better accuracy and can be flexibly applied to different projects.

[0108] Optionally, see Fig.10 , is a schematic diagram of the structure of a traditional arc eddy current sensor provided in this application, including:

[0109] The existing eddy current designs of system suppliers on the market are mostly arc-shaped designs, which have a large volume and high cost. For details, see Fig.10 .

[0110] See also Fig.11 , is a schematic diagram of the structure of an arc eddy current sensor provided by the present application, which is described in detail as follows:

[0111] This solution adopts a low-cost electromagnetic solution design, and the maximum diameter of the coil arrangement is Φ30 mm. Of course, the actual electromagnetic solution can be adjusted and designed according to the corresponding interface size, and is not limited here.

[0112] The sensor structure adopts the form of insert injection molding, integrating the output plug-in with the sensor itself, reducing the cost of additional wiring harness plug-in caused by cylinder plug-in, and greatly reducing the cost of bridge layout. Compared with the mass-produced sensors on the market, the structure has been optimized, the envelope diameter has been reduced from Φ144Max to Φ59mm, and the overall weight has been reduced by two times, which is conducive to overall cost reduction, so that the eddy current sensor has the advantages of small size and light weight.

[0113] See also Fig.12 , which is a traditional wiring harness connection solution for an eddy current sensor provided in this application, comprising:

[0114] PEU (Power Electronics Unit) is an important component in the field of new energy vehicles. It is usually called a power electronic integrated module. PCB (Printed Circuit Board) is a printed circuit board. PCB connects various electronic components (such as resistors, capacitors, integrated circuits, etc.) through circuit patterns and through-holes on it to form a complete circuit system. Among them, the eddy current sensor EM transmits signals and electrical energy through the PEU connector.

[0115] For example, the wiring harness welding methods used in mass-produced sensors on the market are different, and the welding solutions used in traditional designs cannot be flexibly deformed. Once different customers have different requirements for wiring harnesses, a comprehensive redevelopment is required.

[0116] See also Fig.13 , which is a new wiring harness connection solution for eddy current sensors provided in this application, is described in detail as follows:

[0117] The new proposal realizes the design of pluggable wiring harness assembly in the structural design. Different from the wiring harness welding method used in mass-produced sensors on the market, the wiring harness assembly of the sensor designed in this proposal is connected through connector links. The design of the new proposal is conducive to the platformization of sensor stator products. For different projects, it only needs to replace the wiring harness assembly to complete the transformation.

[0118] Optionally, in some embodiments, the present application provides an angular position detection device, including the above-mentioned eddy current sensor, which detects the magnitude and phase of the induced current to determine the angular position of the rotor of the motor to be measured.

[0119] The sensor angle position detection device includes a memory, a processor, a communication interface and a bus, wherein the memory, the processor and the communication interface are connected to each other through the bus.

[0120] The memory may be a read-only memory (ROM), a static storage device, and a random access memory (RAM). The memory may store a program, and when the program stored in the memory is executed by the processor, the processor and the communication interface are used to execute the various steps of the sensor detection method of the embodiment of the present application.

[0121] The processor can be a general-purpose central processing unit (CPU), a microprocessor, an application specific integrated circuit (ASIC), a graphics processing unit (GPU) or one or more integrated circuits to execute relevant programs to implement the functions required to be performed by the units in the device of the embodiment of the present application, or to execute the sensor detection method of the embodiment of the present application.

[0122] The processor may also be an integrated circuit chip with signal processing capability. In the implementation process, each step of the sensor detection method of the embodiment of the present application may be completed by an integrated logic circuit of hardware in the processor or by instructions in the form of software.

[0123] The above-mentioned processor may also be a general-purpose processor, a digital signal processor (digital signal processing, DSP), an ASIC, a field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The various methods, steps and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application may be directly embodied as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory, and combines its hardware to complete the functions required to be performed by the unit included in the sensor detection device of the embodiment of the present application, or executes the sensor detection method of the embodiment of the present application.

[0124] The communication interface uses a transceiver device such as, but not limited to, a transceiver to achieve communication between the sensor detection device and other equipment or a communication network.

[0125] A bus may include a pathway that transfers information between various components of a sensor-sensing device (eg, memory, processor, communication interface).

[0126] It should be noted that although the above-mentioned sensor detection device only shows a memory, a processor, and a communication interface, in the specific implementation process, those skilled in the art should understand that the sensor detection device may also include other devices necessary for normal operation. At the same time, according to specific needs, those skilled in the art should understand that the sensor detection device also includes hardware devices for implementing other additional functions. In addition, those skilled in the art should understand that the sensor detection device may also only include the devices necessary to implement the embodiments of the present application.

[0127] In some other embodiments, the third aspect of the present application provides an electric drive system, including the above-mentioned eddy current sensor; or / and the above-mentioned angle position detection device, having the following technical effects:

[0128] First, one end of the printed circuit board assembly is used as the electromagnetic induction area, and the excitation coil and the receiving coil are injection molded in the electromagnetic induction area with inserts, which effectively reduces the production cost. At the same time, a complete four-layer board is used to complete the drawing of the two receiving coils. In the coil PCB solution designed in this proposal, each layer of the four-layer board completes the arrangement of the receiving coil, so that the strength of the received eddy current signal is higher than that of the arc solution, and the axial position installation redundancy is large. In addition, due to the periodic integrity of the full-circle coil solution, periodic compensation can be performed during the rotation of the rotor in the offline test, which has a strong resistance to radial errors caused by installation, and also enables the single sensor of the eddy current sensor to achieve high precision requirements.

[0129] Second, the output port of the eddy current sensor is a connector, which is connected to the external wiring harness assembly in a linked form. The connector is used as the output port in the eddy current sensor, which is convenient for connecting and disconnecting with the external wiring harness assembly. No welding or special tools are required, which reduces the difficulty and cost of installation and maintenance. At the same time, the existing interface design is not changed, and it can be widely copied and promoted on the existing product structure.

[0130] Third, through the packaging design of different products, it is suitable for oil-cooled / water-cooled electric drive design solutions. For example, in situations where water cooling is required, the potting compound can be designed to allow coolant to flow around the PCB components to take away heat; in the oil cooling solution, the potting compound needs to have better oil resistance and sealing properties.

[0131] Fourth, since the potting compound can provide good sealing protection, it reduces the failure rate of PCB components due to external environmental factors, thereby reducing the cost of maintenance and replacement; at the same time, the automated potting process of the potting compound is relatively simple and fast, which can significantly improve production efficiency and reduce labor costs. In addition, through reasonable potting compound packaging design, the heat dissipation performance of electronic equipment is optimized, reducing performance degradation or damage caused by overheating, thereby extending the service life of the equipment and reducing the overall cost. In summary, it can effectively reduce the cost of driving the electric drive.

[0132] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. An eddy current sensor, characterized in that: include: Eddy current rotor, exciting coil, receiving coil, eddy current control module and printed circuit board assembly; One end of the eddy current rotor is connected to the shaft of the motor to be tested and rotates synchronously; One end of the printed circuit board assembly is an electromagnetic induction zone, the excitation coil and the receiving coil are arranged in the electromagnetic induction zone, and the receiving coil is distributed on the inner side of the excitation coil. The other end of the eddy current rotor is close to the electromagnetic induction zone to form a preset air gap spacing. The eddy current control module is arranged at the other end of the printed circuit board assembly. The eddy current control module is connected to the excitation coil to form a high-frequency oscillating magnetic field, and the eddy current control module is connected to the receiving coil to receive the induced electromotive force.

2. The eddy current sensor according to claim 1, characterized in that: The printed circuit board assembly is at least two-layer boards, and each layer of the boards is provided with a complete cycle of excitation coils and receiving coils, wherein the excitation coil is in a closed ring shape, and the receiving coil is wound and distributed in the closed ring shape.

3. The eddy current sensor according to claim 2, characterized in that: The receiving coil includes a sine winding and a cosine winding which are orthogonally distributed, and is used to obtain a sine-cosine envelope signal.

4. The eddy current sensor according to claim 1, characterized in that: The structure of the electromagnetic induction area includes at least one of an annular structure, a circular structure or a semicircular structure.

5. The eddy current sensor according to claim 1, characterized in that: The eddy current sensor further comprises a housing assembly for accommodating the printed circuit board assembly, and assembling the printed circuit board assembly in the housing assembly.

6. The eddy current sensor according to claim 5, characterized in that: The shape of the housing component matches the shape of the printed circuit board component, and an output port of the eddy current sensor is provided at one end close to the eddy current control module.

7. The eddy current sensor according to claim 6, characterized in that: The output port of the eddy current sensor is a connector, and the connector is externally connected to the wiring harness component in a linked form.

8. The eddy current sensor according to claim 5, characterized in that: If the electromagnetic induction area is an annular structure and the housing component is provided with a through hole, the center of the annular structure is sleeved on the through hole to assemble the printed circuit board assembly.

9. The eddy current sensor according to claim 8, characterized in that: The other end of the eddy current rotor passes through the through-hole member to form a preset air gap distance.

10. The eddy current sensor according to claim 1, characterized in that: Also includes: The potting glue is used to seal the printed circuit board assembly in the housing assembly.

11. The eddy current sensor according to any one of claims 1 to 9, characterized in that: The coil diameter formed by the excitation coil and the receiving coil is less than or equal to 30 mm.

12. The eddy current sensor according to any one of claims 1 to 9, characterized in that: The outer wall of the housing component is provided with symmetrically distributed limiting fixing holes.

13. The eddy current sensor according to any one of claims 1 to 9, characterized in that: The printed circuit board assembly is manufactured by using a PCBA plate making process.

14. The eddy current sensor according to any one of claims 1 to 6, characterized in that: The eddy current control module includes an eddy current chip, an excitation circuit and a receiving circuit. The eddy current chip controls the excitation coil through the excitation circuit to excite a high-frequency oscillating magnetic field. The eddy current chip receives an orthogonal high-frequency signal through the receiving circuit and the receiving coil for demodulation, and outputs a sine and cosine envelope signal.

15. An angle position detection device, characterized in that: The eddy current sensor comprises the eddy current sensor as claimed in any one of claims 1 to 14, and detects the magnitude and phase of the induced current to determine the angular position of the rotor of the motor to be measured.

16. An electric drive system, characterized in that: It comprises the eddy current sensor as described in any one of claims 1 to 14; or / and the angular position detection device as described in claim 15.

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