Slip ring arrangement

Abstract

The application discloses a slip ring device, relates to the field of slip rings, and comprises a stator, a rotor, a first communication unit arranged on the stator, and a second communication unit arranged on the rotor; the first communication unit and the second communication unit each comprise a loop antenna assembly and a signal processing module, the signal processing module is connected with the loop antenna assembly and an external communication line respectively; the signal processing module is used for converting a communication signal of the external communication line into a millimeter wave radio frequency electric signal for exciting the loop antenna assembly to work, and / or demodulating a millimeter wave radio frequency electric signal picked up by the loop antenna assembly into a communication signal; the loop antenna assembly of the first communication unit is arranged opposite to the loop antenna assembly of the second communication unit and is non-contact coupled, and is used for transmitting a millimeter wave signal when the stator and the rotor rotate oppositely, so that the reliability of signal transmission can be improved.

Description

Technical Field

[0001] This application relates to the field of slip rings, and in particular to a slip ring device. Background Technology

[0002] In various rotating equipment (such as direct-drive bases for racing simulators, industrial robots, radar turntables, wind turbines, medical scanners, etc.), continuous signal and / or power transmission between the stator and rotor is typically required. To achieve this, the industry commonly uses slip ring structures as a standard solution. A slip ring typically consists of a conductive ring and brushes that slide in contact with it. Different electrical circuits are connected to the stator and rotor sides, respectively, and the transmission of electrical energy or data signals is accomplished through continuous physical contact during relative rotation.

[0003] However, traditional slip rings rely on the mechanical contact between the brush and the conductive ring to conduct signals. During long-term continuous rotation, the brush and the conductive ring will experience continuous sliding friction, leading to gradual wear of the materials. This wear directly causes increased contact resistance, signal attenuation, and even intermittent disconnections, severely affecting the reliability of signal transmission. Summary of the Invention

[0004] The purpose of this application is to provide a slip ring device that can improve the reliability of signal transmission.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a slip ring device, the device comprising: The stator and the rotor, a first communication unit disposed on the stator, and a second communication unit disposed on the rotor; The first communication unit and the second communication unit each include a loop antenna assembly and a signal processing module, and the signal processing module is connected to the loop antenna assembly and the external communication line, respectively. The signal processing module is used to convert the communication signal of the external communication line into a millimeter-wave radio frequency electrical signal that excites the loop antenna assembly to work, and / or demodulate the millimeter-wave radio frequency electrical signal picked up by the loop antenna assembly into a communication signal; The loop antenna assembly of the first communication unit is disposed opposite to and non-contactly coupled with the loop antenna assembly of the second communication unit, and is used to transmit millimeter-wave signals when the stator and the rotor rotate relative to each other.

[0006] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application provides a slip ring device that uses millimeter-wave frequency band for signal transmission. Its beam characteristics have extremely strong directionality, and the energy is confined to a specific spatial region between the stator and rotor, making it difficult to diffuse into the surrounding space. Therefore, it can effectively avoid electromagnetic interference and reflection scattering generated by motor windings, metal shells and other metal structures, significantly improving communication reliability. At the same time, combined with the uniform layout of the loop antenna in the circumferential direction, the directional transmission path of the millimeter-wave narrow beam remains stable when the stator and rotor rotate relative to each other to any angle, ensuring that the communication link is not interrupted under infinite rotation conditions. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the structure of a slip ring device according to an exemplary embodiment; Figure 2 A functional module diagram of a signal processing module provided in an embodiment of this application. Figure 1 ; Figure 3 A functional module diagram of a signal processing module provided in an embodiment of this application. Figure 2 ; Figure 4 This is a schematic diagram of a loop antenna assembly provided in one embodiment of this application. Detailed Implementation

[0008] The present application will now be described in conjunction with the accompanying drawings of the embodiments.

[0009] Figure 1 This is a schematic diagram of the structure of a slip ring device according to an exemplary embodiment, as shown below. Figure 1 As shown, the above-mentioned device includes: The stator and rotor, a first communication unit disposed on the stator, and a second communication unit disposed on the rotor; For example, the stator is the fixed part (i.e., the non-rotating part) of the device, and the rotor is the rotating part of the device. A first communication unit is fixedly mounted on the stator, and a second communication unit is fixedly mounted on the rotor. Both the first and second communication units are independent modular components, which can be fixed to the corresponding mounting surfaces of the stator and rotor by fasteners (such as screws, clips), adhesives, magnetic connections, etc. The first and second communication units can be arranged opposite each other in the axial direction, maintaining a non-contact gap between them, so that the stator and rotor can rotate freely relative to each other without physical contact.

[0010] The first communication unit and the second communication unit cooperate to achieve communication. Those skilled in the art can flexibly design the communication modes and roles of the first communication unit and the second communication unit.

[0011] In one example, a one-way transmission mode can be configured where one party is fixed as the sender and the other as the receiver. For instance, the first communication unit can be fixed as the sender and the second communication unit as the receiver, and the roles can be reversed.

[0012] In another example, a bidirectional transmission mode can be designed between the two. Bidirectional transmission can further include two types: time-division multiplexing half-duplex communication and synchronous full-duplex communication. Half-duplex is time-division multiplexing bidirectional transmission, supporting only unidirectional signal transmission at any given time. In this case, the transmitting and receiving roles of the first and second communication units alternate: when the first communication unit is the sender, the second communication unit is the receiver, and their roles are reversed after the time period switches. Full-duplex, on the other hand, is synchronous bidirectional transmission, with independent parallel communication in both directions. In this case, both the first and second communication units simultaneously possess sending and receiving functions, acting as both senders and receivers, and can synchronously complete the transmission and reception of millimeter-wave signals.

[0013] Any of the above communication modes can achieve millimeter-wave wireless communication between the stator and rotor without any physical contact.

[0014] The first and second communication units mentioned above each include a loop antenna assembly and a signal processing module, and the signal processing module is connected to the corresponding loop antenna assembly and an external communication line, respectively. The aforementioned signal processing module is used to convert the communication signal of the aforementioned external communication line into a millimeter-wave radio frequency electrical signal that excites the corresponding loop antenna assembly to work, and / or to demodulate the millimeter-wave radio frequency electrical signal picked up by the corresponding loop antenna assembly into a communication signal; The loop antenna assembly of the first communication unit and the loop antenna assembly of the second communication unit are arranged opposite to each other and coupled non-contactly, and are used to transmit millimeter wave signals when the stator and the rotor rotate relative to each other.

[0015] The stator and rotor can be installed in an end-to-end facing configuration, with the stator located at one end of the rotor and its end face facing the rotor's end face. In this configuration, the loop antenna assembly of the first communication unit is located on the stator end face facing the rotor, and the loop antenna assembly of the second communication unit is located on the rotor end face facing the stator. Either of these loop antenna assemblies is used to radiate and / or pick up millimeter-wave signals. The two loop antenna assemblies, located on the stator and rotor respectively, are positioned opposite each other along the axial direction (the direction of the common rotation axis of the stator and rotor), forming a face-to-face non-contact coupling. Furthermore, the two loop antenna assemblies adopt a ring-shaped arrangement, exhibiting omnidirectional and uniform radiation / reception characteristics in the circumferential direction. Therefore, when the stator and rotor rotate relative to each other to any angle, the electromagnetic coupling channel between the two loop antenna assemblies remains stable, without signal interruption or drastic fluctuations due to changes in the rotation angle.

[0016] The signal processing modules in the first and second communication units are used to perform protocol conversion and radio frequency related processing.

[0017] The aforementioned signal processing modules are electrically connected to the loop antenna assembly and external communication lines (such as USB bus, CANFD bus, RS485 bus, EtherCAT bus, etc.). The signal processing modules possess the following bidirectional or arbitrary unidirectional signal processing capabilities: On the one hand, when used as a transmitter, the signal processing module is used to perform protocol encoding, digital-to-analog conversion and radio frequency modulation on the communication signals (such as USB data packets, CANFD data frames, etc.) input from the external communication line, and finally convert them into millimeter-wave radio frequency electrical signals to drive the loop antenna assembly, so as to excite the loop antenna assembly to transmit millimeter-wave wireless signals.

[0018] On the other hand, when used as a receiver, the signal processing module demodulates, converts analog-to-digital signals, and decodes protocols from the millimeter-wave radio frequency signals received and converted by the loop antenna assembly, ultimately restoring them into communication signals recognizable by the external communication line. In other words, when this communication unit acts as a receiver, the signal processing module restores the millimeter-wave signals picked up by the loop antenna assembly into communication signals, which are then output to the target device via the external communication line.

[0019] For example, the aforementioned external communication lines are connected to the communication interfaces of the first and second communication units. The communication interfaces can be located on the outside of each communication unit, facilitating the connection of external devices or sensors by the user. When an external device (such as a steering wheel angle sensor or force feedback controller in a racing simulator) is connected to this device through the communication interface, the bus signal it generates is transparently transmitted from the stator side to the rotor side, or from the rotor side to the stator side, via the aforementioned millimeter-wave non-contact link. The transmission process is completely transparent to the upper-level devices, and the device itself can directly replace the original slip ring without any modification.

[0020] In this embodiment, the stator is fixedly mounted on the base of the rotating device (such as the base of a racing simulator), and the rotor is fixedly mounted on the rotating component of the rotating device (such as a steering wheel shaft). When the rotating component drives the rotor to rotate continuously relative to the stator, the millimeter-wave communication link between the first communication unit and the second communication unit remains uninterrupted, thereby ensuring that various bus signals between the stator and rotor can be transmitted in real time and reliably under conditions of unlimited rotation (such as 900° to 1080° or even multiple rotations), without being limited by the rotation angle or the number of rotations.

[0021] Therefore, this device completely replaces the traditional contact-type signal slip ring. While retaining the power supply slip ring (or using an independent power supply), all signal transmission tasks that originally required mechanical contact between brushes and conductive rings are transferred to millimeter-wave contactless links.

[0022] In one embodiment, a signal processing module with bidirectional signal processing capability may include a microcontroller unit, a physical layer chip, a transmit link, and a receive link. A signal processing module with unidirectional signal processing capability, such as one that only has transmit capability, may include a microcontroller unit, a physical layer chip, and a transmit link (excluding the receive link). Similarly, if it only has receive capability, it may include a microcontroller unit, a physical layer chip, and a receive link (excluding the transmit link).

[0023] In one example, such as Figure 2 As shown, the signal processing module in the first communication unit and / or the second communication unit includes: a first communication interface, a microcontroller unit, a physical layer chip, a first differential line, and a first transmission unit; The first communication interface is used to connect to an external communication line to receive external communication signals; Microcontroller unit, used to encode external communication signals to generate protocol data; The physical layer chip is used to convert protocol data into differential baseband signals; The first differential line is used to transmit the differential baseband signal to the first transmission unit; The first transmission unit is radio frequency coupled to the loop antenna assembly and is used to modulate the differential baseband signal onto the millimeter-wave carrier to generate a millimeter-wave radio frequency electrical signal.

[0024] The first communication interface, the first differential line, and the first transmission unit are the main components of the transmission link.

[0025] Specifically, the first communication interface is located outside the signal processing module of the first and / or second communication unit and is used to connect to external communication lines. The first communication interface is a pluggable connector, and specific types include, but are not limited to, USB interfaces (such as USB Type-A, USB Type-B, USB Type-C), CANFD interfaces, RS485 interfaces, and EtherCAT interfaces. Users can select one or more communication interface types according to their actual application requirements. External devices or sensors are connected to the signal processing module through the first communication interface, and the bus signals (communication signals) they generate are processed by the signal processing module and transmitted to the other end via a millimeter-wave link.

[0026] The microcontroller unit is electrically connected to the first communication interface. Specifically, the general-purpose input / output pins or dedicated communication interface pins of the microcontroller unit are connected to the corresponding signal pins of the first communication interface. In this example, the microcontroller unit is used to receive bus signals from an external communication line.

[0027] The microcontroller integrates memory and multiple communication protocol controllers, and comes pre-installed with embedded firmware. The firmware includes various communication protocol stacks, including but not limited to USB, CANFD, RS485, and EtherCAT stacks. The microcontroller uses the protocol stacks in the firmware to parse and repackage the received bus signals. In the transmission direction, the microcontroller receives bus signals from external devices through the first communication interface, encodes the bus signals according to the target communication protocol, extracts the payload data and reassembles it into a protocol data frame according to the protocol format, and transmits the protocol data to the physical layer chip through the internal data bus.

[0028] The physical layer chip is electrically connected to the microcontroller unit. Specifically, the digital interface pins of the physical layer chip are connected to the corresponding data bus pins of the microcontroller unit, and in this example, it is used at least to receive protocol data sent by the microcontroller unit.

[0029] The physical layer chip integrates serializers / deserializers, clock data recovery circuits, equalizers, and driver circuits. Its core function is to convert between digital protocol data and analog differential baseband signals. In this example, in the transmission direction, the physical layer chip receives parallel protocol data from the microcontroller unit, and after parallel-to-serial conversion, encoding, scrambling, etc., it is converted into a differential baseband signal and output to the differential line through the differential signal output pin.

[0030] The first differential line connects the first physical layer chip and the first transmission unit. Specifically, the first differential line is a pair of differential traces on a printed circuit board (PCB), with one end connected to the differential signal pin of the first physical layer chip and the other end connected to the differential signal pin of the first transmission unit. The first differential line adopts strict differential pair routing rules (equal length, equal spacing, constant impedance) and is used for bidirectional transmission of differential baseband signals between the first physical layer chip and the first transmission unit.

[0031] The first transmission unit is electrically connected to the first differential line and is also RF coupled to the loop antenna assembly of the first communication unit. Specifically, the differential signal pins of the first transmission unit are connected to the first differential line, and the RF input / output ports of the first transmission unit are connected to the feed interface of the corresponding loop antenna assembly through microstrip lines or coplanar waveguides.

[0032] The first transmission unit internally contains millimeter-wave radio frequency front-end circuitry, specifically including a power amplifier (PA), a low-noise amplifier (LNA), a mixer, a local oscillator, a phase shifter, and a transmit / receive switch (if only unidirectional transmission is required, the transmit / receive switch is not needed, or can be disabled). The core function of the first transmission unit is to achieve frequency conversion and power amplification between the differential baseband signal and the millimeter-wave radio frequency electrical signal. The differential baseband signal is received from the first differential line, upconverted to the millimeter-wave band by a mixer, amplified by a power amplifier, and then output to the loop antenna assembly for outward radiation.

[0033] The phase shifter in the first transmission unit is used to control the phase of the millimeter-wave signal, enabling independent phase control of each radiating unit, thereby forming specific beam pointing and polarization characteristics.

[0034] The transmit / receive switch is used to switch the transmit / receive state in time division duplex mode, so that the antenna can work in transmit mode or receive mode in different time slots.

[0035] In another example, such as Figure 3 As shown, the signal processing module in the second communication unit and / or the first communication unit includes at least: a second transmission unit, a second differential line, a physical layer chip, a microcontroller unit, and a second communication interface; The second communication interface, the second differential line, and the second transmission unit are the main components of the receiving link.

[0036] The second transmission unit is radio frequency coupled to the loop antenna assembly (connected to the feed interface of the loop antenna assembly via a feed line) and is used to convert the received millimeter wave radio frequency signal into a differential baseband signal after the coupled loop antenna assembly converts the millimeter wave (wireless) signal and outputs the millimeter wave radio frequency signal. The second differential line is used to transmit the differential baseband signal to the physical layer chip; The physical layer chip is used to recover differential baseband signals into protocol data; The microcontroller unit is used to decode protocol data to recover communication signals. The second communication interface is used to output communication signals to an external communication line.

[0037] For example, the second transmission unit internally includes the aforementioned millimeter-wave radio frequency front-end circuit. Specifically, after receiving the millimeter-wave radio frequency signal, the second transmission unit first performs low-noise amplification via a low-noise amplifier (LNA) to suppress noise introduced by subsequent circuits. The amplified radio frequency signal is then sent to a mixer for down-conversion with the local oscillator signal, shifting the spectrum of the millimeter-wave radio frequency signal to baseband to obtain a differential baseband signal. The second transmission unit outputs the differential baseband signal to the second differential line through its differential signal output pin.

[0038] The second differential line transmits the differential baseband signal from the second transmission unit to the physical layer chip. The second differential line is a pair of differential traces, which adopt a strict equal length and equal spacing design to ensure signal integrity. In the receiving direction, it realizes low-loss and low-interference transmission of differential baseband signal from the transceiver unit to the physical layer chip.

[0039] In the receiving direction, the physical layer chip receives the differential baseband signal from the differential line through its differential signal input pin. After processing such as equalization, clock recovery, decoding, and serial-to-parallel conversion, it recovers the parallel protocol data and transmits it to the microcontroller unit via the digital interface. Specifically: the physical layer chip receives the differential baseband signal from the second differential line through its differential signal input pin. The equalizer integrated inside the physical layer chip performs equalization processing on the received differential baseband signal to compensate for high-frequency losses during transmission; the clock data recovery circuit extracts the clock signal from the differential baseband signal and uses the extracted clock to sample and decide the signal; the deserializer converts the serial differential baseband signal into parallel protocol data, and simultaneously performs decoding (such as 8b / 10b decoding or 64b / 66b decoding) and descrambling processing to recover the parallel protocol data. The recovered protocol data is transmitted to the microcontroller unit through the digital interface pin of the physical layer chip.

[0040] In the receiving direction, the microcontroller receives protocol data from the physical layer chip via its internal data bus. It decodes the protocol data according to the target communication protocol, reconstructs the bus signal, and outputs the reconstructed bus signal to an external device through the communication interface. Specifically: the microcontroller receives protocol data from the physical layer chip through its data bus pins. The embedded firmware running in the microcontroller decodes the protocol data according to a pre-configured target communication protocol (such as USB, CANFD, RS485, or EtherCAT, consistent with the protocol used by the sender), extracts the payload from the protocol data frame, and reconstructs the original bus signal. The reconstructed bus signal is then transmitted to the second communication interface via the microcontroller's general-purpose input / output pins or dedicated communication interface pins.

[0041] The second communication interface outputs the bus signal restored by the microcontroller to the external communication line, and finally transmits it to the external device or sensor connected to the second communication interface. This completes the full receiver direction signal processing flow.

[0042] Based on the connection relationships and working principles of the above components, taking the first communication unit as the transmitter and the second communication unit as the receiver as an example, the loop antenna assembly of the first communication unit acts as the transmitting antenna, radiating the millimeter-wave carrier signal outward. The millimeter-wave signal passes through the air gap between the stator and rotor (a distance of 2mm to 5mm) and is received by the loop antenna assembly of the second communication unit. The loop antenna assembly of the second communication unit is positioned opposite to the loop antenna assembly of the first communication unit, and both are arranged in a ring shape in the circumferential direction. Therefore, regardless of the relative rotation angle of the stator and rotor, the loop antenna assembly of the second communication unit can reliably receive the millimeter-wave signal transmitted by the loop antenna assembly of the first communication unit, and the received signal strength does not change with the rotation angle.

[0043] The signal transmission path is: External communication line → First communication interface of the first communication unit → Microcontroller unit (protocol encoding, generating protocol data) → Physical layer chip (protocol data → differential baseband signal) → First differential line → First transmission unit (differential baseband signal → millimeter wave radio frequency signal) → Loop antenna assembly of the first communication unit (transmitting millimeter wave signal) → Loop antenna assembly of the second communication unit (receiving millimeter wave signal) → Second transmission unit (millimeter wave radio frequency signal → differential baseband signal) → Second differential line → Physical layer chip (differential baseband signal → protocol data) → Microcontroller unit (protocol decoding, restoring to bus signal) → Second communication interface (outputting bus signal to external communication line).

[0044] The following describes the loop antenna assembly.

[0045] In one embodiment, each loop antenna assembly includes X concentric loop antennas with different diameters; each loop antenna includes N radiating elements; X and N are positive integers not less than 2.

[0046] X loop antennas are set concentrically, meaning all loop antennas share a common center. Each loop antenna has a different diameter and is arranged radially from the inside out. The radiating elements belonging to the same loop antenna are uniformly distributed along the circumference, thus forming a uniform ring-shaped radiation field across the entire circumference.

[0047] Those skilled in the art can flexibly design the number of X as needed, for example, 2, 3, 4, etc. This will not be elaborated upon here. Figure 4 As shown, the loop antenna assembly in the first communication unit and / or the second communication unit includes two concentric loop antennas with different diameters; the feed interfaces of the two loop antennas are radially opposite each other.

[0048] In this embodiment, the loop antenna assembly specifically includes two concentric loop antennas with different diameters, namely an inner loop antenna and an outer loop antenna. The centers of the two loop antennas coincide, and the feed interfaces of the two loop antennas are radially opposite, located on opposite sides of the center (i.e., arranged opposite each other along the diameter direction, with an included angle of 180°), forming two physically isolated and non-interfering millimeter-wave transmission channels. This dual-ring dual-channel structure can be adapted to the aforementioned unidirectional transmission, half-duplex time-division bidirectional transmission, and full-duplex synchronous bidirectional transmission modes. For example, a pair of inner-ring antennas (or outer-ring antennas) on the stator and rotor are used for unidirectional signal transmission from the stator to the rotor, and a pair of outer-ring antennas (or inner-ring antennas) are used for unidirectional signal transmission from the rotor to the stator, thereby achieving full-duplex synchronous communication. Alternatively, the dual-ring channels can be merged and multiplexed, and half-duplex bidirectional communication can be achieved by switching the transmit and receive roles in a time-division manner. Another example is the use of only a single channel to achieve unidirectional transmission in a fixed direction. Yet another example is the use of two pairs of ring antennas on the stator and rotor to carry different data streams in the same transmission direction, thereby achieving dual-channel parallel communication in the same transmission direction and effectively improving the data transmission rate.

[0049] The two loop antenna assemblies are aligned face-to-face, with a distance of 2mm to 5mm between them.

[0050] In another embodiment, in all the above embodiments, a shielding structure is provided between adjacent loop antennas among the X loop antennas.

[0051] To reduce signal crosstalk between adjacent loop antennas, a shielding structure is installed between them. Specifically, a shielding structure is installed in the annular region between the inner and outer loop antennas. This shielding structure can be a metal through-hole, a metal ring (such as a copper or aluminum ring), a plastic ring (with a metal layer plated on its surface), or a ring of absorbing material (such as ferrite or absorbing sponge). A grounded metal ring can be used, which can achieve both physical isolation and provide good electromagnetic shielding, effectively suppressing electromagnetic coupling and signal crosstalk between the inner and outer loop antennas.

[0052] In other embodiments of this application, the center arc length spacing between adjacent radiating elements in all the above embodiments is 0.5λ to 0.8λ, where λ is the effective wavelength in the medium.

[0053] As mentioned above, each loop antenna includes N radiating elements. Those skilled in the art can flexibly design the value of N as needed, such as 2, 3, 8, 12, etc., which will not be elaborated further.

[0054] The radiating elements are uniformly distributed along the circumference of the loop antenna, with a center-to-center arc length spacing of 0.5λ to 0.8λ between adjacent radiating elements, where λ is the effective wavelength in the medium (i.e., the propagation wavelength of electromagnetic waves in the dielectric substrate). This spacing range is determined by optimizing the mutual coupling effect between the radiating elements: if the spacing is less than 0.5λ, the mutual coupling between the radiating elements is too strong, affecting the independent radiation characteristics of each element; if the spacing is greater than 0.8λ, grating lobes (i.e., undesirable sidelobes) may appear during large-angle scanning, leading to a deterioration of the radiation pattern. Setting the spacing between 0.5λ and 0.8λ can improve impedance matching by utilizing a moderate mutual coupling effect, ensure that grating lobes do not appear during wide-angle scanning, and maintain a high axial ratio flatness to guarantee the stability of circular polarization performance.

[0055] Each radiating element is a patch antenna structure disposed on the surface of a dielectric substrate. The radiating element can be a square patch, circular patch, rectangular patch, ring patch, or a variation thereof. For example, circular polarization radiation can be achieved by chamfering the corners of a square patch (i.e., removing two opposite corners). Specifically, by chamfering (cutting off corners) on the square patch, the current distribution on the patch is perturbed, creating a 90° phase difference between the two orthogonal polarization components, thus forming a circularly polarized wave. The size of the chamfer can be determined through simulation optimization based on the target circular polarization performance.

[0056] For example, deformation can be performed on the circular patch, specifically by creating asymmetrical slots (such as cross slots, arc slots, etc.) on the circular patch to achieve circular polarization.

[0057] Of course, the radiating element can also adopt other radiator forms suitable for the millimeter-wave frequency band. The specific form of the radiating element does not constitute a limitation on the present invention, as long as circular polarization radiation can be achieved in the millimeter-wave frequency band.

[0058] In one embodiment, if there are two loop lines, one loop antenna is a left-hand circularly polarized antenna and the other loop antenna is a right-hand circularly polarized antenna.

[0059] The two loop antennas employ different circular polarization methods: one loop antenna is left-hand circularly polarized, and the other is right-hand circularly polarized. For example, the inner loop antenna uses a left-hand circularly polarized design (achieved by chamfering the radiating patch in a specific direction), while the outer loop antenna uses a right-hand circularly polarized design (the chamfer direction is opposite to that of the inner loop); or the inner loop is right-hand circularly polarized, and the outer loop is left-hand circularly polarized. In this dual-circuit design, the left-hand circularly polarized antenna on the stator side automatically corresponds to the left-hand circularly polarized antenna on the rotor side, and the right-hand circularly polarized antenna on the stator side automatically corresponds to the right-hand circularly polarized antenna on the rotor side. Regardless of the rotation angle, the polarization of the antennas on both sides of the stator and rotor always matches, thus ensuring the stability of the communication link and avoiding signal fading caused by polarization mismatch.

[0060] In other embodiments, the angle between a first line connecting the center point of the radiating patch to the center of the circle and a second line connecting the two lines is equal to the phase shift of the radiating patch. The second line is the line connecting the center point of the radiating patch with a phase shift of 0° to the center of the circle. For example, if the phase shift of a radiating patch is 90°, the angle between the first line connecting the center point of the radiating patch to the center of the circle and the second line connecting the two lines is 90°.

[0061] In other embodiments, each loop antenna is divided into a left-handed and a right-handed spiral region along its circumference. An isolation structure (such as a grounding slot, microstrip gap, or metal isolation wall) is provided between the feed branches of the left-handed and right-handed spiral regions to prevent signal crosstalk between the two spiral regions. The radiating elements of the inner and outer loop antennas are electrically connected via symmetrical phase delay lines, and the left-handed and right-handed spiral regions are independently excited by different feed ports. This embodiment and the aforementioned "single loop antenna with a single spiral direction" are two independent design options that can be selected as needed.

[0062] In one embodiment, each loop antenna assembly further includes a microstrip phase-shifting network. The microstrip phase-shifting network comprises N fed microstrip lines, each fed microstrip line being directly connected to one of the N radiating elements (i.e., the first fed microstrip line connects to the first radiating element, the second fed microstrip line connects to the second radiating element, and so on, with the Nth fed microstrip line connecting to the Nth radiating element). The length of the fed microstrip lines is determined based on the phase of the corresponding radiating element. In this embodiment, the N radiating elements are fed in parallel.

[0063] Following the arrangement of the radiating elements in the circular array (numbered sequentially along the circumference as element 1, element 2, ..., element N), the length of the feed microstrip line corresponding to each radiating element increases sequentially by a length increment ΔL, repeating cyclically. Each cycle contains Q radiating elements, and within the same cycle, adjacent radiating elements receive an equal and increasing feed phase difference ΔL. =360 / Q.

[0064] Taking Q=4 as an example, the length of the microstrip line cycles through four phases: 0°, 90°, 180°, and 270°, i.e.: Phase 0° (i=1,5,9…) → Length L0; Phase 90° (i=2,6,10…) → L0+ΔL; Phase 180° (i=3,7,11…) → L0+2ΔL; Phase 270° (i=4,8,12…) → L0+3ΔL; Where ΔL is the microstrip line length increment required to achieve a 90° phase shift.

[0065] Then, for any radiating element i (i is not less than 1), the length of the feed microstrip line connected to it is Li = L0 + r ΔL, where L0 is the feed line reference length corresponding to the first radiating element within the period, and ΔL is the phase difference ΔL. The required microstrip line length increment (360° / Q) is r=(i-1)modQ, where mod represents the modulo operation.

[0066] It should be noted that if i starts from 0, then r = imod Q.

[0067] In this embodiment, N fed microstrip lines form a sequential rotating feed network, providing N radiating elements with progressively increasing equal phase differences. This microstrip phase-shifting network generates progressively increasing equal phase differences, enabling the orthogonal components generated by each radiating element to be synthesized in the far-field space, thereby achieving broadband circular polarization characteristics.

[0068] In one embodiment, N radiating elements are arranged in series along the feed microstrip line. In the transmission direction from the feed end to the end, the feed microstrip line is partially or completely continuously varied in width to achieve an impedance gradient effect.

[0069] The locations where the width gradually changes include, but are not limited to, the following four types of areas: 1. Main feed line segment: from the output of the RF transceiver unit to the feed port of the loop antenna; gradient function: to match the output impedance of the RF front-end with the input impedance of the antenna port; 2. Feed entry section: The microstrip line segment from the antenna feed port to the first radiating element.

[0070] 3. The entire feed microstrip line between adjacent radiating elements; 4. The connection between the radiating unit and the microstrip line.

[0071] The specific ways to implement width gradients include, but are not limited to, the following: Firstly, linear gradient—the width decreases linearly along the transmission direction (e.g., from 0.6mm to 0.3mm), thus achieving a smooth transition of impedance. This method is the simplest to implement and has the best stability.

[0072] Secondly, tapered gradient (also known as triangular gradient) – adjacent microstrip segments are connected by triangular or trapezoidal transition segments to achieve a gradual change in width, which has strong matching performance and does not take up extra length.

[0073] Third, exponential gradient – ​​the width changes continuously along the transmission direction according to an exponential function, exhibiting ultra-wideband characteristics and optimal rotational stability.

[0074] Fourthly, the microstrip line is divided into multiple equal-width straight segments with a step change in width between adjacent segments. The overall impedance transformation is completed gradually through multiple steps, making the manufacturing process easier.

[0075] The above-mentioned various gradient methods and four types of gradient areas can be selected individually or combined arbitrarily according to actual design needs.

[0076] Smooth impedance transitions were achieved at the main feed line section, feed entrance section, between adjacent radiating elements, and at the connection points between radiating elements and microstrip lines. This effectively eliminated impedance discontinuities caused by abrupt changes in microstrip line width, significantly reducing signal reflection and VSWR, and improving transmission efficiency in the millimeter-wave band. Especially during relative rotation of the stator and rotor, the excellent impedance matching significantly reduced the variation in antenna input impedance with the rotation angle, maintaining a stable VSWR and preventing drastic gain fluctuations with the rotation angle, thus ensuring stable communication performance during rotation.

[0077] In one embodiment, the above-described loop antenna assembly comprises N radiating elements connected in series, divided into M segments. Each segment includes P radiating elements and a microstrip line segment extending from the side of the current segment's feed microstrip line. The microstrip line segment is used to compensate for the phase error between the first and last radiating elements within the segment; N is greater than M, and P is greater than 1. The current segment feed microstrip line refers to the microstrip line located between the first and last radiating elements of the current segment, connecting all radiating elements in the current segment in series.

[0078] Among them, the ends of the aforementioned microstrip segments are left suspended to form open-circuit stubs, or the ends are grounded through metal vias to form short-circuit stubs; When the actual phase difference between the first and last radiating units within a segment is greater than the target phase difference, the aforementioned microstrip segment is a short-circuit stub. When the actual phase difference between the first and last radiating elements within a segment is less than the target phase difference, the aforementioned microstrip segment is an open-circuit stub.

[0079] Taking N=8, M=4, P=2 as an example: the 8 radiating elements are numbered sequentially as element 1 to element 8 along the ring array and are divided into 4 segments. Each segment includes 2 radiating elements. The first segment includes element 1 and element 2, the second segment includes element 3 and element 4, the third segment includes element 5 and element 6, and the fourth segment includes element 7 and element 8. In each segment, a microstrip line segment (parallel stub) extends from the side of the feed microstrip line connecting the two radiating elements in that segment.

[0080] The microstrip line segment extends vertically or at a certain angle from the side of the feed microstrip line. There are two ways to handle its end: first, the end is suspended and not grounded, forming an open-circuit stub; second, the end is connected to the grounding layer through a metal via, forming a short-circuit stub.

[0081] An open-circuit stub is a small section of microstrip extending from the side of the main microstrip line, with its end suspended. Its length is approximately λg / 8 or λg / 10 (typically 1mm to 3mm in the millimeter-wave band). An open-circuit stub (length less than λg / 4) is equivalent to a capacitor, exhibiting capacitive impedance characteristics, and can cause phase lag in the segment it belongs to.

[0082] A short-circuit stub is a small section of microstrip extending from the side of the main microstrip line, with its end grounded through a metal via, and its length is approximately λg / 4. The short-circuit stub is equivalent to an inductor, exhibiting inductive impedance characteristics, and can cause the phase of the segment it belongs to to lead.

[0083] The selection of branch type is determined based on the comparison between the actual phase difference between the first and last radiating units within the segment and the target phase difference: When the actual phase difference between the first and last radiating elements within a segment is greater than the target phase difference (i.e., the actual phase shift is too large and the phase is leading), a short-circuit stub is used for that microstrip segment. The short-circuit stub is equivalent to an inductor, and inductive compensation is introduced to pull the leading phase back to the target value.

[0084] When the actual phase difference between the first and last radiating elements within a segment is less than the target phase difference (i.e., the actual phase shift is too small and the phase lags), an open-circuit stub is used for this microstrip segment. The open-circuit stub is equivalent to a capacitor, and capacitive compensation is introduced to pull the lagging phase back to the target value.

[0085] For example, suppose an antenna has 8 radiating elements connected in series, and the target phase difference between adjacent radiating elements is 45°. This antenna can be divided into 4 segments, each with 2 elements, and a parallel stub is drawn from the middle of each segment. Taking elements 1 and 2 as examples, the phase of element 1 and the phase of element 2 are obtained through simulation or actual measurement. The difference between the two is calculated to obtain the actual phase shift of the main line segment from element 1 to 2. If the target phase shift is 45° and the measured phase shift is 50°, then the phase error Δ If err = +5° (phase lead), a short-circuit stub should be added to this segment. The length L of the short-circuit stub is based on the absolute value of the phase error |Δ The err| and the microstrip guide wavelength λg are expressed by the formula L=|Δ err|×λ g / 360° is calculated and determined. Assume λ g =28.62mm, then L=5×28.62 / 360≈0.40mm.

[0086] If the measured phase shift is 40°, then the phase error Δ err = -5° (phase lag), this segment should have open-circuit branches, and the branch length should be calculated according to the above formula.

[0087] The width W of an open-circuit or short-circuit stub can be determined based on the dielectric substrate parameters and the target characteristic impedance, using the general engineering microstrip line width calculation formula. Methods for determining the target characteristic impedance include: matching the system impedance (e.g., 50Ω), selecting a high impedance (70Ω~100Ω) to improve phase adjustment sensitivity, or matching the mainline impedance to reduce impedance reflection.

[0088] Through the segmented phase compensation structure described above, the phase error in each segment can be corrected independently, thereby ensuring that the phase distribution of each radiating element in the entire loop antenna assembly meets the design target, effectively improving the antenna's radiation efficiency and circular polarization purity.

[0089] The above example, using P=2, illustrates the basic principle of the segmented compensation structure. When the number of radiating elements P in each segment is greater than 2, the lead-out position of the parallel stub on the microstrip line fed by that segment will affect the phase compensation effect. If the stub is placed biased towards one end of the segment, the phase compensation effect on the other end will be weakened, resulting in the phase error of the radiating elements at both ends of the segment not being effectively corrected simultaneously. Therefore, it is necessary to determine the optimal lead-out position of the stub.

[0090] Therefore, this embodiment provides a general rule for determining the placement of stubs, namely the phase midpoint principle: ensuring that the phase difference between the parallel stub and the radiating units at both ends of the segment is equal or as close as possible. The basic idea of ​​this principle is to place the parallel stub at the phase midpoint of the microstrip line fed by the segment, so that the transmission phase from the stub position to the radiating unit at the beginning of the segment is approximately equal to the transmission phase to the radiating unit at the end of the segment, thereby ensuring that the compensation introduced by the stub can be applied evenly throughout the entire segment.

[0091] Specifically, for each segment containing P radiating elements (numbered sequentially along the signal transmission direction as element 1, element 2, ..., element P), the electrical phase difference between adjacent radiating elements is Δ. (That is, the electrical phase difference corresponding to the distance between adjacent units). The total phase difference from the first radiating unit (unit 1) to the last radiating unit (unit P) of this segment is (P-1)×Δ The phase corresponding to the midpoint of the phase is (P-1)×Δ Parallel stubs should be drawn from the midpoint of the phase of the feed microstrip line of the segment, so that the phase difference from the stub to the first radiating element of the segment is approximately equal to the phase difference to the last radiating element of the segment [both approximately (P-1)×Δ]. .

[0092] Based on the parity of P, the specific placement positions of the parallel branches are as follows: (a) The placement of branches when P is an odd number.

[0093] When P is odd, let P = 2k + 1 (k is a positive integer, k ≥ 1), and the segment has an odd number of radiating elements. In this case, the phase midpoint is located after the middle radiating element of the segment. Specifically, the (k+1)th radiating element is the middle radiating element of the segment, and the phase midpoint is located on the feed microstrip line between the (k+1)th and (k+2)th radiating elements. Therefore, the parallel stub should extend from the side of the feed microstrip line between the (k+1)th and (k+2)th radiating elements.

[0094] Taking P=3 as an example (k=1): the segment includes 3 radiating elements (element A, element B, element C), and the electrical phase difference between adjacent elements is Δ. Then the total phase difference from element A to element C is 2Δ The midpoint of the phase is Δ This is the midpoint of the phase between element A and element B. Since the phase difference between element A and element B is Δ... This location is precisely at the midpoint between cell A and cell B. Therefore, the parallel stub should extend from the side of the feed microstrip line between cells A and B, rather than between cells B and C. This location results in a phase difference of Δ from the stub to cell A. The phase difference to unit C is 3Δ Although they are not exactly equal, they represent the optimal compromise.

[0095] Taking P=5 as an example (k=2): the segment includes 5 radiating elements (element 1, 2, 3, 4, 5), with a total phase difference of 4Δ. The midpoint of the phase is 2Δ The location is on the feed microstrip line between the 3rd (intermediate) and 4th units. Therefore, the parallel stub should extend from the side of the feed microstrip line between units 3 and 4.

[0096] (ii) The placement of branches when P is an even number.

[0097] When P is even, let P = 2k (k is a positive integer, k ≥ 1), and the segment has an even number of radiating elements. In this case, the phase midpoint is located between the two middle radiating elements of the segment. Specifically, the k-th and (k+1)-th radiating elements are the two middle radiating elements of the segment, and the phase midpoint is located on the feed microstrip line between the k-th and (k+1)-th radiating elements. Therefore, the parallel stub should extend from the side of the feed microstrip line between the k-th and (k+1)-th radiating elements.

[0098] Taking P=4 as an example (k=2): the segment includes 4 radiating elements (element A, element B, element C, element D), with a total phase difference of 3Δ. The midpoint of the phase is 1.5Δ The phase difference between element A and element B is Δ. The phase difference between element A and element C is 2Δ. Therefore, 1.5Δ Located between cells B and C. Therefore, the parallel stub should extend from the side of the feed microstrip line between cells B and C, such that the phase difference between the stub and cell A is 1.5Δ. The phase difference to element D is 1.5Δ. Both ends are completely symmetrical and equal.

[0099] Taking P=6 as an example (k=3): the segment includes 6 radiating elements (element 1, 2, 3, 4, 5, 6), with a total phase difference of 5Δ. The midpoint of the phase is 2.5Δ. The location is on the feed microstrip line between the 3rd and 4th cells. Therefore, the parallel stub should extend from the side of the feed microstrip line between cells 3 and 4.

[0100] In one embodiment, the system further includes a power generation module comprising an induction coil disposed on the stator side and a permanent magnet disposed on the rotor side. The induction coil is electrically connected to the power supply terminal on the stator side for supplementing power to the first communication unit. As the permanent magnet rotates with the rotor, it generates a changing magnetic field in the induction coil. Based on Faraday's law of electromagnetic induction, an induced electromotive force is generated in the induction coil, outputting alternating current.

[0101] In one example, the design could be as follows: The stator and rotor are arranged opposite each other. The stator circuit board is set at the end of the stator facing the rotor, and the rotor circuit board is set at the end of the rotor facing the stator. Both the stator circuit board and the rotor circuit board are multilayer printed circuit board structures.

[0102] The stator circuit board includes a first antenna layer, a first shielding layer, and an induction coil layer stacked along its thickness direction. The first antenna layer faces the rotor and has a loop antenna assembly (i.e., a millimeter-wave antenna) of the first communication unit disposed thereon. The induction coil layer houses an induction coil, which can be disposed on the rotor-facing surface of the induction coil layer. The induction coil can be a loop generating coil etched into the bottom layer of the PCB board and arranged coaxially and concentrically with the loop millimeter-wave antenna. The first antenna layer and the induction coil layer are separated by a first shielding layer (ground layer or power layer) to achieve electromagnetic isolation and prevent the magnetic field of the generating module from interfering with the radiation performance of the millimeter-wave antenna. The signal processing module in the first communication unit can be disposed on a layer other than the induction coil layer, or on an independent functional layer, and maintain electromagnetic isolation from the induction coil layer.

[0103] The aforementioned rotor circuit board includes a second antenna layer, a second shielding layer, and a magnet mounting layer stacked sequentially. The second antenna layer faces the stator and has a loop antenna assembly (i.e., the corresponding receiving antenna) of the second communication unit mounted on it. The magnet mounting layer has a permanent magnet, which can be fixedly mounted on the surface of the magnet mounting layer facing the stator. The second antenna layer and the magnet mounting layer are separated by a second shielding layer (grounding layer or power layer) to achieve electromagnetic isolation. The signal processing module in the second communication unit can be located on a layer other than the magnet mounting layer, or on an independent functional layer, and maintain electromagnetic isolation from the magnet mounting layer.

[0104] The basic working principle of the power generation module is as follows: The permanent magnet on the rotor side rotates with the rotor, generating a rotating magnetic field. The induction coil on the stator side is located in this rotating magnetic field, and the magnetic field lines periodically pass through the coil, generating an induced electromotive force (EMF) in the coil. The magnitude of the induced EMF is proportional to the magnetic induction intensity of the permanent magnet, the number of turns of the coil, the coil area, and the rotor speed. The alternating current output from the induction coil is processed by subsequent circuits and fed into the main power bus to provide supplementary power to the communication unit.

[0105] The GND of the power generation module and the GND of the first communication unit share a common ground to avoid ground loop interference.

[0106] In one example, the stator-side power supply includes a power supply and a main power bus. The power supply and the main power bus are in a subordinate relationship; the power supply is electrically connected to the main power bus, and the electrical energy output from the power supply is transmitted to each load through the main power bus. Those skilled in the art can flexibly select the types of power supply and main power bus. For example, the main power bus can be an onboard DC conductive trace, and the power supply can be a constant DC regulated power supply (5V or 12V), or it can be an energy storage battery such as a lithium battery or lead-acid battery.

[0107] In another embodiment, the power generation module in all the above embodiments further includes the following devices located on the stator side: a rectifier bridge, a filter capacitor, a voltage regulator, and a diode; For example, the rectifier bridge, filter capacitor, voltage regulator and diode can be disposed on the surface of the induction coil layer facing away from the rotor in the stator circuit board.

[0108] The two ends of the aforementioned induction coil are connected to the AC input terminal of the aforementioned rectifier bridge, and the aforementioned filter capacitor is connected in parallel between the positive and negative terminals of the DC output terminal of the aforementioned rectifier bridge. The positive and negative terminals of the DC output terminal of the aforementioned rectifier bridge are respectively connected to the positive input terminal and the negative input terminal of the aforementioned voltage regulator. The positive terminal of the voltage regulator is connected to the anode of the diode, the cathode of the diode is connected to the positive terminal of the main power bus, and the negative terminal (GND) of the voltage regulator is connected to the negative terminal of the main power bus; the main power bus belongs to the power supply terminal. The aforementioned first communication unit is connected in parallel to the main power bus. Specifically, the positive terminal of the power supply of the first communication unit is connected in parallel to the positive terminal of the main power bus, and its negative terminal is connected to the negative terminal of the main power bus.

[0109] The two ends of the induction coil are connected to the AC input terminals of the rectifier bridge. Specifically, the two output terminals of the induction coil (i.e., the two ends of the toroidal generator coil) are connected to the two AC input pins (AC1 and AC2) of the rectifier bridge, respectively. The AC current generated by the induction coil (the voltage and current fluctuate with the rotor speed) is rectified by the rectifier bridge through full-wave rectification, converting the alternating positive and negative AC voltage into a unidirectional pulsating DC voltage. A Schottky rectifier bridge or a fast recovery rectifier bridge can be used to reduce the forward voltage drop and switching losses during rectification, thereby improving power generation efficiency. The withstand voltage of the rectifier bridge should be determined based on the maximum peak voltage that the induction coil may generate; typically, a rectifier bridge with a withstand voltage of not less than 50V is selected.

[0110] A filter capacitor (e.g., a small-capacity filter capacitor of 10μF to 47μF) is connected in parallel between the positive and negative terminals of the rectifier bridge's DC output to smooth pulsating DC current and reduce voltage ripple after rectification. Specifically, the positive terminal of the filter capacitor is connected to the positive terminal of the rectifier bridge's DC output, and the negative terminal is connected to the negative terminal of the rectifier bridge's DC output (i.e., common ground GND). The capacitance value of the filter capacitor can be determined based on the operating frequency and load current, selecting an appropriate value while ensuring a smoothing effect. Electrolytic capacitors or ceramic capacitors can be used, and their voltage rating should be determined based on the maximum output voltage.

[0111] The positive and negative terminals of the rectifier bridge's DC output are connected to the positive and negative input terminals of the voltage regulator, respectively. Specifically, the positive DC output of the rectifier bridge is connected to the positive input terminal (VIN pin) of the voltage regulator, and the negative DC output (GND) of the rectifier bridge is connected to the negative input terminal (GND pin) of the voltage regulator. The voltage regulator is used to convert the fluctuating DC voltage after rectification and filtering into a stable DC voltage.

[0112] The voltage regulator has a Vout terminal and a GND terminal at the output. The Vout terminal outputs the set stable voltage (e.g., 5V or 12V), and the GND terminal is the common ground. A step-up / step-down switching regulator (such as the TPS63020) can be used, which has the advantage that even if the voltage output by the induction coil is lower than the target voltage, the regulator can still boost it to above the target voltage to ensure the normal operation of the subsequent circuitry; when the voltage output by the induction coil is higher than the target voltage, the regulator can also step it down to the target voltage, keeping the output voltage stable at the set value.

[0113] The integrated switching transistor within the voltage regulator rapidly switches between on and off states, working in conjunction with an external inductor to achieve voltage boost or buck conversion. The voltage feedback pin at the regulator's output is connected to an output voltage sampling resistor divider network for real-time monitoring of the output voltage and closed-loop adjustment of the switching duty cycle, thereby ensuring the stability and accuracy of the output voltage. The regulator's enable pin (EN pin) is an optional control pin; when time-sharing control is required, the regulator can be turned on and off via an external signal.

[0114] The positive terminal (Vout pin) of the voltage regulator's output is connected to the anode of the diode, and the cathode of the diode is connected to the positive terminal of the main power bus; the negative terminal (GND pin) of the voltage regulator's output is directly connected to the negative terminal of the main power bus. This diode acts as an anti-reverse current diode (or an ideal diode circuit), utilizing its unidirectional conductivity to ensure that current can only flow from the voltage regulator's output to the main power bus, preventing reverse current from flowing back into the voltage regulator and the power generation module. Schottky diodes can be used because they have a low forward voltage drop (typically 0.3V to 0.5V) and a fast switching speed, effectively reducing conduction losses and improving power generation efficiency.

[0115] In alternative implementations, an ideal diode circuit (such as a MOSFET-based active rectifier) ​​can be used instead of a Schottky diode to further reduce the on-state voltage drop and power loss. However, in this embodiment, a Schottky diode can be used because of its simple structure, low cost, and reliable operation.

[0116] It should be noted that the negative terminal of the DC output of the aforementioned rectifier bridge, the negative terminal of the filter capacitor, the negative terminal of the input (GND pin) and the negative terminal of the output (GND terminal) of the voltage regulator, and the cathode of the diode (connected to the negative terminal of the main power bus) together constitute the common ground node (GND) of the power generation module. This common ground node is connected to the negative terminal of the power supply of the first communication unit at a single point to avoid ground loop interference.

[0117] Through the above-described exemplary connection method, the electrical energy generated by the power generation module can be fed into the main power bus to provide supplementary power to the first communication unit, while not affecting the normal power supply of the main power bus to other loads.

[0118] In other embodiments of this application, a TVS diode (e.g., SMCJ30A, breakdown voltage 30V) can be connected in parallel between the positive and negative input terminals of the voltage regulator to prevent voltage spikes in the induction coil from damaging the voltage regulator and its downstream circuitry when the rotor speed is too high. Specifically, the cathode of the TVS diode is connected to the positive input terminal of the voltage regulator, and the anode of the TVS diode is connected to the negative input terminal (GND) of the voltage regulator. When the voltage output by the induction coil exceeds the breakdown voltage of the TVS diode, the TVS diode quickly turns on, clamping the overvoltage spike within a safe voltage range and protecting the downstream circuitry from overvoltage surges. The breakdown voltage of the TVS diode should be determined based on a combination of the voltage regulator's maximum input voltage rating and the maximum possible output voltage of the induction coil.

[0119] Based on the connection relationships of the above components, the complete signal and energy flow of the power generation module is as follows: Rotor rotation → Permanent magnet generates rotating magnetic field → Induction AC current is generated in induction coil → Rectifier bridge (AC → Pulsating DC) → Filter capacitor (smooths ripple) → Voltage regulator (stabilizes voltage to target value, such as 5V or 12V) → Anti-backflow diode (one-way conduction, prevents backflow) → Main power bus positive terminal → Power positive terminal of the first communication unit, while current flows back from the main power bus negative terminal to the voltage regulator GND, forming a complete circuit.

[0120] Through the above circuit structure, the alternating current generated by the induction coil is converted into stable direct current, which is then isolated by the anti-backflow diode and fed into the main power bus to provide supplementary power to the first communication unit, thereby improving the device's self-powering capability and reliability.

[0121] In one embodiment, the main power bus is specifically a DC bus (e.g., onboard DC bus trace), and the power supply is a constant DC regulated power supply (5V or 12V). The aforementioned diode (anti-reverse current diode) is specifically used to conduct forward when the output voltage of the voltage regulator is higher than the rated voltage of the DC bus, so that the voltage regulator supplies power to the DC bus; and to cut off when the output voltage of the voltage regulator is lower than the voltage of the DC bus.

[0122] The DC bus is connected to a normally supplied DC regulated power supply (such as 5V or 12V). In this embodiment, the first communication unit is normally powered by the DC bus, and the power generation module only provides auxiliary power.

[0123] Because the actual operating speed of the slip ring rotor fluctuates, the induced electromotive force of the induction coil changes with the speed. The generated output voltage, after rectification and voltage stabilization, dynamically varies within a certain range. When the rotor speed is high and the generated output voltage is higher than the bus voltage, the anti-backflow diode conducts forward, and the self-generated energy is sent to the positive bus, diverting some of the load power consumption of the communication unit. The self-generated power source shares the power consumption, reducing the bus output current and achieving auxiliary power supply and energy saving. For example, when the bus voltage is 12V and the regulated output voltage is 12.6V, the diode conducts, and the electrical energy generated by the coil directly supplies the first communication unit, reducing the bus output.

[0124] When the rotor speed is low and the generator output voltage is lower than the bus voltage, the anti-backflow diode is reverse-biased and cut off, disconnecting the generator branch from the bus. All power consumption is then borne solely by the DC bus, preventing backflow from the bus to the coil. Thus, relying on the unidirectional conduction characteristic of the anti-backflow diode, automatic switching between auxiliary power supply and disconnection is achieved without the need for additional control circuitry.

[0125] To achieve an output voltage higher than the DC bus voltage even at low speeds, the number of turns in the induction coil can be further optimized to ensure that, at the lowest relative speeds between the stator and rotor, the rectified and regulated output voltage is higher than the rated voltage of the DC bus. The design steps are as follows: The first step is to determine the minimum operating speed ωmin and the maximum operating speed ωmax of the slip ring. The goal is to ensure that the output voltage is higher than the rated voltage of the bus after rectification and regulation at ωmin (e.g., 12V).

[0126] The second step is to select the parameters of the permanent magnet (e.g., N35 neodymium iron boron, magnetic induction intensity B=0.4T) and determine the coil area A=πr. 2 (r is the average radius of the coil).

[0127] The third step is to calculate the required number of turns D, ensuring that the no-load peak voltage Vpeak at the lowest speed ωmin is greater than 15V (with margin): D = Vpeak / (B×A×ωmin); Where B is the magnetic flux density of the selected permanent magnet.

[0128] The above design ensures that the output voltage of the generator module remains higher than the bus voltage even at the lowest operating speed, thus ensuring that the anti-backflow diode can conduct in the forward direction under most operating conditions and realize the auxiliary power supply function.

[0129] In one embodiment, the slip ring device in all the above embodiments further includes a time-sharing control circuit. The time-sharing control circuit is electrically connected to the circuit of the induction coil and is used to disconnect the circuit of the induction coil when the first communication unit is communicating and to close the circuit of the induction coil when the first communication unit is idle, thereby allowing the power generation module to enter the working mode to generate electricity during the working gap of the first communication unit, avoiding the electromagnetic interference of the power generation module from affecting the communication quality, and recovering electrical energy during the communication gap.

[0130] For example, the time-division control circuit includes a microcontroller and an electronic switch. The microcontroller can be a miniature control chip, such as STM32, ATmega328P, ESP32, etc. The function of the microcontroller is to detect whether the first communication unit is in transmit / receive state (e.g., by reading the enable signal of the antenna power amplifier in the first communication unit, or according to a preset communication timing); and output a control level according to the detected state.

[0131] The microcontroller's input pins are used to receive antenna operating status indication signals. Antenna circuits (such as power amplifiers and transmit / receive switches) typically have enable pins or status indication pins; for example, a high level indicates transmitting / receiving, and a low level indicates idle. This pin is connected to the microcontroller's GPIO input pin (e.g., PA0), and the microcontroller reads this level to determine whether the antenna is in a communication time slot.

[0132] The output of the microcontroller is connected to the control terminal of the electronic switch. The electronic switch can be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), whose gate is connected to the GPIO output pin of the microcontroller (e.g., PB1) through a current-limiting resistor (e.g., 100Ω), and whose source and drain are connected in series in the circuit of the induction coil.

[0133] The output logic of this GPIO pin is as follows: When the antenna is communicating, the microcontroller outputs a low level (0V), disconnecting the MOSFET in the power generation circuit, disconnecting the induction coil circuit, and stopping the power generation module from working, thus avoiding electromagnetic interference affecting the communication quality; when the antenna is idle, the microcontroller outputs a high level (3.3V or 5V), closing the MOSFET, closing the induction coil circuit, and the power generation module works normally, generating electricity during the antenna working interval.

[0134] As an alternative, the microcontroller's GPIO output pins can also be directly connected to the enable pin (EN pin) of the voltage regulator, achieving time-sharing control by controlling the regulator's on and off states. When connecting, pay attention to level matching: if the regulator's EN pin is active high, the microcontroller will generate electricity when the output is high and stop when it is low; if EN pin is active low, the logic is reversed, which can be achieved using a simple transistor inverting circuit.

[0135] The microcontroller's own power supply (usually 3.3V or 5V) can be drawn from the main power system (DC bus or battery) through a low-dropout regulator (such as AMS1117-3.3), sharing the main power supply with the antenna circuit, but high-frequency noise is isolated through ferrite beads or small resistors. The microcontroller's GND, the antenna circuit's GND, and the power generation module's GND share a common ground point to avoid ground loops.

[0136] In one embodiment, the power generation module in all the above embodiments further includes a first energy storage capacitor, which is connected in parallel between the positive and negative terminals of the voltage regulator output. When the circuit of the induction coil is closed, when the output voltage of the voltage regulator is greater than the rated voltage of the DC bus, the aforementioned diode is forward-biased, and the output of the voltage regulator supplies power to the DC bus. When the circuit of the induction coil is closed, if the output voltage of the voltage regulator is less than the rated voltage of the DC bus, the diode is cut off, the output of the voltage regulator cannot supply power to the DC bus, the voltage regulator charges the first energy storage capacitor, and after the voltage of the first energy storage capacitor rises above the bus voltage, it discharges to the DC bus through the anti-reverse-current diode.

[0137] Specifically, during the communication period of the first communication unit, the induction coil circuit is open, there is no power output, and the antenna is powered entirely by the DC bus. During the idle period of the first communication unit, the induction coil circuit is closed to start generating electricity. The physical path of the generated electrical energy is as follows: when the generated voltage is higher than the bus voltage, the anti-backflow diode is turned on, and the electrical energy flows to the bus; when the generated voltage is lower than the bus voltage, the anti-backflow diode is turned off, and the electrical energy cannot flow to the bus and is temporarily stored in the first energy storage capacitor. After the capacitor voltage rises above the bus voltage, it is discharged to the rear bus via the anti-backflow diode.

[0138] With the above-mentioned time-sharing charging structure, even if the generator voltage is insufficient to directly supply power to the bus at low speeds, the electrical energy will not be wasted. Instead, it will be temporarily stored in the energy storage capacitor and released to the bus after the voltage accumulates and rises, effectively improving energy utilization efficiency.

[0139] Optionally, a large-capacity electrolytic capacitor (470μF~1000μF, 1000μF as an example) can be connected in parallel between the main power supply positive bus and GND to smooth the bus voltage and improve voltage stability when the antenna is supplied with a large instantaneous current. This capacitor is not necessary for the energy storage of the power generation module and can be selected according to actual needs.

[0140] The buck-boost chip, turns optimization, and time-sharing storage can be used individually or in any combination.

[0141] In one embodiment, the power supply at the aforementioned power supply terminal is a battery, and a second energy storage capacitor is connected in parallel between the positive and negative terminals of the battery; thus, this structure enables high power supply and low energy storage. When the circuit of the induction coil is closed and the output voltage of the voltage regulator is higher than the voltage of the battery, the diode is forward-biased and the voltage regulator supplies power to the first communication unit. If there is a remaining voltage output by the voltage regulator after power supply, the voltage regulator charges the battery and the second energy storage capacitor (i.e., float charging). When the induction coil circuit is closed and the output voltage of the voltage regulator is lower than the voltage of the battery, the diode is turned off, and the battery and / or the second energy storage capacitor supply power to the first communication unit. Due to the unidirectional conduction characteristic of the diode, the battery will not flow back to the power generation module, nor will it consume power to the induction coil.

[0142] The second energy storage capacitor is used to absorb and store the surplus electrical energy generated by the first communication unit during idle periods. When the millimeter-wave antenna transmits at high power instantaneously and the load current increases sharply, it quickly releases electrical energy to provide power in coordination and buffer the impact of peak power consumption on the battery. At the same time, it smooths out the fluctuations in the generated voltage and power supply ripple caused by the rotor speed fluctuations, stabilizes the working power supply voltage of the first communication unit, and improves the power supply quality of the radio frequency circuit.

[0143] The capacitance value of the second energy storage capacitor can be determined based on the antenna's peak power consumption. An exemplary 100μF to 470μF electrolytic capacitor can be used, and it can be paired with a 10μF high-frequency ceramic capacitor (MLCC). The functions of the two types of capacitors are as follows: the electrolytic capacitor (e.g., 100μF) provides 1-2A of instantaneous peak current for the millimeter-wave antenna, absorbs pulse current surges during time-sharing charging, and smooths voltage drops when the battery is low. The high-frequency ceramic capacitor (e.g., 10μF) filters out MHz-level switching ripple from the buck-boost regulator and charging management chip, compensates for the poor high-frequency characteristics of the electrolytic capacitor, and suppresses power supply noise in the RF circuit. 100μF is the baseline value; if the antenna peak current exceeds 2A, it can be adjusted to 220μF or 470μF. The 10μF ceramic capacitor does not require adjustment and represents the optimal capacitance range for high-frequency filtering.

[0144] Furthermore, it can be combined with time-sharing control: During the communication time slot, the first communication unit's power generation circuit is disconnected and it does not generate electricity. The diode has no input and is naturally cut off, with the battery providing power throughout. When the first communication unit enters an idle time slot, it closes the coil circuit and starts generating electricity. At this time, the aforementioned high-supply, low-storage operation can be achieved, which will not be elaborated here.

[0145] In other embodiments of this application, when the power supply is a battery, the above-mentioned power generation module may further include a dedicated charging management chip to prevent the voltage regulator output from being directly connected to the battery via a diode. The circuit connection sequence after adding the charging management chip is as follows: AC output from generator coil → rectifier bridge → filter capacitor → voltage regulator (boost / buck) → charging management chip → anti-backflow diode → battery positive terminal.

[0146] Taking a single-cell lithium-ion / polymer battery (4.2V) as an example, the TP4056 charging management chip can be used. The specific connection method is as follows: the 5V output (Vout) of the voltage regulator is connected to the VCC pin of the TP4056, the BAT pin of the TP4056 is connected to the positive terminal of the battery, and the GND pin of the TP4056 is connected to the common ground. The TP4056 has built-in reverse current protection, so an external reverse current protection diode can be omitted. A 10μF ceramic capacitor and a 100μF–470μF electrolytic capacitor (close to the battery) are connected in parallel between the positive and negative terminals of the battery. The external resistor connected to the PROG pin of the charging management chip is used to set the maximum charging current; it is recommended to set it to 0.5–0.8 times the maximum output current of the induction coil.

[0147] The external resistor connected to the PROG pin of the charging management chip is used to set the maximum charging current. It is recommended to set it to 0.5 to 0.8 times the maximum output current of the induction coil.

[0148] The GND of the power generation module, the GND of the voltage regulator, the GND of the charging management chip, the negative terminal of the battery, and the GND of the antenna are all grounded at a single point.

[0149] It should be noted that the first energy storage capacitor (22μF~100μF) at the voltage regulator output and the second energy storage capacitor (100μF~470μF+10μF ceramic capacitor) at the battery terminals serve different purposes: the first energy storage capacitor at the voltage regulator output is mainly used to ensure the stability of the voltage regulator itself (preventing oscillation), filter out high-frequency ripple from the voltage regulator's switching frequency, and provide transient current to the input terminal of the charging management chip; the second energy storage capacitor at the battery terminals is mainly used to provide instantaneous large current during antenna transmission, filter out residual ripple at the output terminal of the charging chip, and smooth the battery's output impedance. They complement each other and cannot be substituted for one another.

[0150] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A slip ring device, characterized in that, The device includes: The stator and the rotor, a first communication unit disposed on the stator, and a second communication unit disposed on the rotor; The first communication unit and the second communication unit each include a loop antenna assembly and a signal processing module, and the signal processing module is connected to the loop antenna assembly and the external communication line, respectively. The signal processing module is used to convert the communication signal of the external communication line into a millimeter-wave radio frequency electrical signal that excites the loop antenna assembly to work, and / or demodulate the millimeter-wave radio frequency electrical signal picked up by the loop antenna assembly into a communication signal; The loop antenna assembly of the first communication unit is disposed opposite to and non-contactly coupled with the loop antenna assembly of the second communication unit, and is used to transmit millimeter-wave signals when the stator and the rotor rotate relative to each other.

2. The slip ring device according to claim 1, characterized in that, The signal processing module in the first communication unit and / or the second communication unit includes: a first communication interface, a microcontroller unit, a physical layer chip, a first differential line, and a first transmission unit; The first communication interface is used to connect to an external communication line to receive external communication signals; Microcontroller unit, used to encode external communication signals to generate protocol data; The physical layer chip is used to convert protocol data into differential baseband signals; The first differential line is used to transmit the differential baseband signal to the first transmission unit; The first transmission unit is radio frequency coupled to the loop antenna assembly and is used to modulate the differential baseband signal onto the millimeter-wave carrier to generate a millimeter-wave radio frequency electrical signal.

3. The slip ring device according to claim 1, characterized in that, The signal processing module in the second communication unit and / or the first communication unit includes: a second transmission unit, a second differential line, a physical layer chip, a microcontroller unit, and a second communication interface; The second transmission unit is radio frequency coupled to the loop antenna assembly and is used to demodulate the received millimeter-wave radio frequency signal into a differential baseband signal after the coupled loop antenna assembly converts the millimeter-wave signal and outputs the millimeter-wave radio frequency signal. The second differential line is used to transmit the differential baseband signal to the physical layer chip; The physical layer chip is used to recover differential baseband signals into protocol data; The microcontroller unit is used to decode protocol data to recover communication signals. The second communication interface is used to output communication signals to an external communication line.

4. The slip ring device according to claim 1, characterized in that, Each loop antenna assembly includes X concentric loop antennas with different diameters; each loop antenna includes N radiating elements; X and N are positive integers not less than 2.

5. The slip ring device according to claim 4, characterized in that, In X loop antennas, a shielding structure is set between adjacent loop antennas.

6. The slip ring device according to claim 4, characterized in that, The center-to-center arc length spacing between adjacent radiating elements is 0.5λ to 0.8λ, where λ is the effective wavelength in the medium.

7. The slip ring device according to claim 4, characterized in that, Each loop antenna assembly also includes a microstrip phase-shifting network, which consists of N feed microstrip lines. Each of the N feed microstrip lines is directly connected to one of the N radiating elements. The length of the feed microstrip line is obtained according to the phase of the corresponding radiating element.

8. The slip ring device according to claim 7, characterized in that, If the number of loop antennas is 2, one loop antenna is a left-hand circularly polarized antenna and the other loop antenna is a right-hand circularly polarized antenna.

9. The slip ring device according to claim 7, characterized in that, N radiating elements are arranged in series along the feed microstrip line. In the transmission direction from the feed end to the end, the feed microstrip line is partially or completely gradually changed in width.

10. The slip ring device according to claim 1, characterized in that, In the ring antenna assembly, the N radiating elements connected in series are divided into M segments. Each segment includes P radiating elements and a microstrip line segment extending from the side of the current segment's feed microstrip line. The microstrip line segment is used to compensate for the phase error between the first and last radiating elements in the segment. N is greater than M, and P is greater than 1. The current segment's feed microstrip line refers to the microstrip line located between the first and last radiating elements of the current segment, which connects all the radiating elements in the current segment.

11. The slip ring device according to claim 10, characterized in that, The end of the microstrip line segment is left suspended to form an open-circuit stub, or the end is grounded through a metal via to form a short-circuit stub; When the actual phase difference between the first and last radiating units within a segment is greater than the target phase difference, the microstrip segment is a short-circuit stub. When the actual phase difference between the first and last radiating units within a segment is less than the target phase difference, the microstrip segment is an open-circuit stub.

12. The slip ring device according to claim 1, characterized in that, It also includes a power generation module, which includes an induction coil disposed on the stator side and a permanent magnet disposed on the rotor side. The induction coil is electrically connected to the power supply terminal on the stator side and is used to supplement power supply to the first communication unit.

13. The slip ring device according to claim 12, characterized in that, The stator and rotor are arranged opposite each other, with a stator circuit board at the end of the stator facing the rotor and a rotor circuit board at the end of the rotor facing the stator; The stator circuit board includes a first antenna layer, a first shielding layer, and an induction coil layer stacked along the thickness direction, wherein the first antenna layer faces the rotor, and the induction coil layer is provided with an induction coil. The rotor circuit board includes a second antenna layer, a second shielding layer, and a magnet mounting layer stacked sequentially, wherein the second antenna layer faces the stator, and the magnet mounting layer is provided with permanent magnets.

14. The slip ring device according to claim 13, characterized in that, The power generation module also includes: a rectifier bridge, a filter capacitor, a voltage regulator, and diodes; The two ends of the induction coil are connected to the AC input terminal of the rectifier bridge, the filter capacitor is connected in parallel between the positive and negative terminals of the DC output terminal of the rectifier bridge, and the positive and negative terminals of the DC output terminal of the rectifier bridge are respectively connected to the positive and negative input terminals of the voltage regulator. The positive terminal of the voltage regulator's output is connected to the anode of the diode, the cathode of the diode is connected to the positive terminal of the main power bus, and the negative terminal of the voltage regulator's output is connected to the ground along with the negative terminal of the main power bus; the main power bus belongs to the power supply terminal. The positive terminal of the power supply of the first communication unit is connected in parallel to the positive terminal of the main power bus, and the negative terminal of the power supply of the first communication unit is connected to the negative terminal of the main power bus.

15. The slip ring device according to claim 14, characterized in that, The main power bus is a DC bus; The diode is used to conduct forward when the output voltage of the voltage regulator is higher than the rated voltage of the DC bus, so that the voltage regulator supplies power to the DC bus; and to cut off when the output voltage of the voltage regulator is lower than the voltage of the DC bus.

16. The slip ring device according to claim 15, characterized in that, The slip ring device also includes a time-sharing control circuit, which is electrically connected to the circuit of the induction coil and is used to disconnect the circuit of the induction coil when the first communication unit is communicating and to close the circuit of the induction coil when the first communication unit is idle.

17. The slip ring device according to claim 16, characterized in that, The power generation module also includes a first energy storage capacitor, which is connected in parallel between the positive and negative terminals of the voltage regulator output. When the circuit of the induction coil is closed, when the output voltage of the voltage regulator is greater than the rated voltage of the DC bus, the diode conducts in the forward direction, and the output of the voltage regulator supplies power to the DC bus. When the circuit of the induction coil is closed, if the output voltage of the regulator is less than the rated voltage of the DC bus, the diode is turned off, and the regulator charges the first energy storage capacitor.

18. The slip ring device according to claim 14, characterized in that, The power supply at the power supply terminal is a battery, and a second energy storage capacitor is connected in parallel between the positive and negative terminals of the battery. When the circuit of the induction coil is closed and the output voltage of the voltage regulator is higher than the voltage of the battery, the diode is forward-biased and the voltage regulator supplies power to the first communication unit. If there is residual voltage after power supply, the voltage regulator charges the battery and the second energy storage capacitor. When the circuit of the induction coil is closed and the output voltage of the voltage regulator is lower than the voltage of the battery, the diode is turned off, and the battery and / or the second energy storage capacitor supply power to the first communication unit.

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