A charging magnetic coupling mechanism based on strong coupling and its load identification method

Abstract

The present invention provides a strong-coupling charging magnetic coupling mechanism and its load identification method, comprising a transmitting coil, a receiving coil, and a ferrite. The coupling coefficient between the transmitting coil and the receiving coil is constant. The transmitting side is provided with a capacitor and an inductor, the inductor being obtained by short-circuiting the primary. The receiving side has a load. By resonating the capacitor and inductor to achieve a constant voltage output independent of the load, the load resistance can be calculated. Accurate load identification can better meet the requirements of the control strategy.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, in particular to a charging magnetic coupling mechanism based on strong coupling and a load identification method thereof. Background Art

[0002] Wireless Power Transfer (WPT) technology offers significant advantages in safety, convenience, and reliability due to its contactless transmission of electrical energy. With the development of portable electronic devices, electric vehicles, and the Internet of Things (IoT), the need for efficient and portable charging solutions has become imperative. Traditional wired charging, while mature and cost-effective, is susceptible to sparks and fire hazards due to its use of direct metal contact. Furthermore, the increasing number of electrical devices requires the inconvenience of multiple power cords. Wireless charging offers advantages such as greater operational flexibility, strong weather resistance, low maintenance, high safety, support for charging multiple devices, and convenience. It holds enormous potential for application in various industrial sectors, including electric vehicles, portable electronics, biomedical equipment, mineral extraction systems, and underwater applications.

[0003] Existing wireless charging systems utilize a traditional planar magnetic core structure, resulting in a two-dimensional, diffuse magnetic field. During the charging process, magnetic field energy is easily affected by positional offsets, resulting in low magnetic field utilization. Eddy current losses are a significant issue at high frequencies. Furthermore, in wireless charging systems, the load is a key parameter affecting system output power and efficiency. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a charging magnetic coupling mechanism based on strong coupling and a load identification method thereof, which can better meet the requirements of the control strategy through accurate identification of the load.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a load identification method based on a strong-coupling charging magnetic coupling mechanism, comprising a transmitting coil, a receiving coil, and a ferrite; the coupling coefficient between the transmitting coil and the receiving coil is constant; the transmitting side is provided with a capacitor and an inductor, the inductor being obtained by the primary inductance when the primary is short-circuited; the receiving side has a load; and a constant voltage output independent of the load is achieved by resonating the capacitor and the inductor, thereby realizing the calculation of the load resistance.

[0006] In a preferred embodiment, the compensation capacitor C 1 Primary-side inductance when the secondary is short-circuited L r Connect in series, connected on the transmitting side;

[0007] Calculate the operating angular frequency ω r :

[0008] .

[0009] In a preferred embodiment, the capacitor C 1 Primary-side inductance when the secondary is short-circuited L r After resonance, we get:

[0010]

[0011] in, ω is the system operating angular frequency, L m It is the transmitting coil L 1 Primary-side inductance when the secondary is short-circuited L r The difference between them, n is the transformation ratio of the ideal transformer in all main reference models, I Lm For inductance L m The current on R L-AC is the equivalent load on the AC side, U 1 is the AC voltage on the transmitting side, U 2 is the AC voltage at the receiving side, I 1 is the initial current measurement, I R AC equivalent load R L-AC The current on Figure 9 As shown;

[0012] According to the above formula, the DC side resistance R L-DC Calculated:

[0013] .

[0014] The present invention also provides a charging magnetic coupling mechanism based on strong coupling, which relies on the load identification method based on the strong coupling charging magnetic coupling mechanism to perform load identification; the ferrite is specifically a hollow cylinder, and the transmitting coil and the receiving coil are surrounded along the inner wall of the hollow cylindrical ferrite; the central axes of the ferrite, the transmitting coil and the receiving coil are located in the same straight line; the ferrite, the transmitting coil and the receiving coil are arranged from the outside to the inside.

[0015] The present invention also provides a charging magnetic coupling mechanism based on strong coupling, which relies on the load identification method based on the strong coupling charging magnetic coupling mechanism to perform load identification; the ferrite is specifically provided with a first ferrite and a second ferrite, the first ferrite is provided with a first annular groove, and the second ferrite is provided with a second annular groove; the first annular groove is used to place the receiving coil, and the second annular groove is used to place the transmitting coil.

[0016] In a preferred embodiment, the thickness of the receiving coil is consistent with the depth of the first annular groove; the thickness of the transmitting coil is consistent with the depth of the second annular groove.

[0017] In a preferred embodiment, the transmitting coil and the receiving coil are both wound with Litz wire.

[0018] Compared with the prior art, the present invention has the following beneficial effects: three-dimensional focusing of the spatial magnetic field is achieved through the composite structure design of the ferrite shell and the embedded coil.

[0019] (1) The coil gap matching physical plug-in mechanism of Scheme 1 not only avoids arcing caused by direct contact, but also achieves strong coupling and precise alignment. The embedded coil and magnetic core integrated design of Scheme 2 reduces the size of the mechanism, increases the power density, and enhances the utilization of the magnetic field.

[0020] (2) Wired plug-in coupling mechanism: Since the distance between the transmitting coil and the receiving coil is relatively close, the ferrite on the receiving side can be removed, and then the unilateral compensation topology is used to remove the receiving side compensation, thereby realizing a lightweight design of the wireless charging system.

[0021] (3) The charging coupling mechanism proposed in this paper can solve the problem of difficulty in identification caused by coupling between the load and the mutual inductance, accurately identify the load, and thus flexibly adjust the output power according to different loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a 3D model of a wired plug-in coupling mechanism according to a preferred embodiment of the present invention;

[0023] Figure 2 A schematic diagram of a wired plug-in coupling mechanism along the YOZ section of a preferred embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of an application scenario of a plug-in coupling mechanism charging system according to a preferred embodiment of the present invention;

[0025] Figure 4 A schematic diagram of a 3D model of a compact coupling mechanism according to a preferred embodiment of the present invention;

[0026] Figure 5A schematic diagram of a YOZ cross section of a compact coupling mechanism according to a preferred embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of an application scenario of a wireless charging system with a compact coupling mechanism according to a preferred embodiment of the present invention;

[0028] Figure 7 Schematic diagram of the SN topology of a wireless power transmission system according to a preferred embodiment of the present invention;

[0029] Figure 8 A schematic diagram of the LCLN topology structure of a wireless power transmission system according to a preferred embodiment of the present invention;

[0030] Figure 9 All main reference models of the wireless power transmission system of the preferred embodiment of the present invention, where (a) is a schematic diagram of the SN topology and (b) is a schematic diagram of the LCLN topology;

[0031] Figure 10 This is an equivalent circuit diagram of the primary side of the SN system according to a preferred embodiment of the present invention;

[0032] Figure 11 The voltage and current phase diagram of the SN system according to the preferred embodiment of the present invention;

[0033] Figure 12 A simplified circuit diagram of an LCLN system according to a preferred embodiment of the present invention is shown;

[0034] Figure 13 This is an equivalent circuit diagram of the primary side of the LCLN system according to a preferred embodiment of the present invention;

[0035] Figure 14 This is a voltage and current phase diagram of the LCLN system according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form, and it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0039] This invention proposes a charging coupling mechanism suitable for strong coupling. This coupling mechanism utilizes a composite structure of solenoid windings and a magnetic core, characterized by a ferrite housing composed of high-permeability ferrite and an embedded coil structure. Each coupling mechanism achieves three-dimensional focusing of the spatial magnetic field through a specific winding arrangement and gap coordination with the magnetic core.

[0040] First, the wired plug-in charging coupling mechanism proposed by the present invention is as follows Figure 1 As shown in the figure, the transmitting device is a hollow cylindrical structure. From the outside to the inside, the system consists of a ferrite layer, a transmitting coil layer, and a receiving coil area. Both the receiving coil and the transmitting coil adopt a solenoid coil structure, where the transmitting structure consists of a hollow cylinder with an embedded transmitting coil. The cross section of the coupling mechanism along the YOZ parallel plane is shown as follows: Figure 2 The ferrite is specifically hollow cylindrical, and the transmitting coil and receiving coil are wound along the inner wall of the hollow cylindrical ferrite; the central axes of the ferrite, transmitting coil, and receiving coil are located on the same straight line; the ferrite, transmitting coil, and receiving coil are arranged from the outside to the inside.

[0041] Application scenarios of using this wired plug-in charging coupling mechanism charging system include Figure 3 As shown, during charging, the transmitting coil is physically inserted over the receiving coil to achieve wireless charging. This charging method retains the ease of use of a traditional charging gun, allows for better alignment, and avoids arcing caused by direct contact, ensuring efficient and safe energy transmission. Because this design brings the transmitting and receiving coils closer together, it is possible to consider removing the ferrite structure on the receiving side, achieving a lightweight design.

[0042] Wired plug-in contact charging solutions are becoming a research hotspot for high-power scenarios, as they combine the physical certainty of traditional plug-in and unplugging with the security of wireless transmission. Their lack of full contact makes them more compatible with a wider range of vehicle models and devices compared to traditional plug-in configurations. This plug-in design avoids full contact while providing mechanical guidance, making it more stable than traditional wireless charging. This design also reduces alignment challenges and achieves stronger coupling. Because the plug-in position is fixed, the system's coupling coefficient is fixed, effectively avoiding the coupling of load and mutual inductance during parameter identification and reducing the difficulty of load identification.

[0043] The present invention further proposes a compact coupling mechanism, such as Figure 4 As shown; including: the ferrite is specifically provided with a first ferrite and a second ferrite, the first ferrite is provided with a first annular groove, and the second ferrite is provided with a second annular groove; the first annular groove is used to place the receiving coil, and the second annular groove is used to place the transmitting coil.

[0044] The first ferrite and the second ferrite are integrally formed of high magnetic permeability ferrite material and have a disc-shaped structure. Concentric annular grooves are provided on the surface, and the depth of the grooves matches the thickness of the coil.

[0045] Transmitter coil: Made of Litz wire and embedded in the bottom layer of ferrite groove.

[0046] Receiving coil: Made of Litz wire, embedded in the upper layer of the ferrite groove. The cross section of the coupling mechanism along the YOZ parallel plane is as follows Figure 5 shown.

[0047] Application scenarios of compact coupling mechanism wireless charging system include Figure 6 During the charging process, the measurement module moves the transmitter directly below the receiver. The ferrite base wraps around the transmitter / receiver coils, creating a closed magnetic circuit that concentrates the magnetic flux lines within the grooves, enhancing coupling and improving magnetic field utilization. This structure is suitable for wireless charging systems with strong coupling, such as those using the SN topology.

[0048] This paper proposes a load identification method for the aforementioned magnetic coupling mechanism. This system utilizes a unilateral compensation topology, reducing the weight of the receiving side by employing a transmitter-side compensation network. The Series-None (SN) and Inductor-Capacitor-Inductor-None (LCL-N) topologies are used as examples. The transmitting side utilizes a full-bridge inverter, while the receiving side employs an uncontrolled rectifier bridge. V INV ( V REC )and U 1( U 2) Indicates the DC voltage and AC voltage on the transmitting side (receiving side), L 1. L 2 represent the transmitting coil and the receiving coil respectively. C 1 is the compensation capacitor.

[0049] SN topology load identification solution:

[0050] Will Figure 7 、 8 The loosely coupled converter model in is replaced by all the main reference models, and we get Figure 9 , Figure 7 correspond Figure 9 (a), Figure 8 correspond Figure 9 (b) The parameters in the figure are shown in formula (1).

[0051]

[0052] according to Figure 9 (a), by adding the capacitorC 1 and inductor L r Resonance, to achieve constant voltage output regardless of the load, where L r It can be obtained as the primary inductance when the secondary is short-circuited.

[0053]

[0054] Where, ω r is the system operating angular frequency. Since the transmitting coil and the receiving coil are fixed in position and the mutual inductance is fixed when the magnetic coupling mechanism of the present invention is used for charging, it is considered that the L r , L m is known. Equivalent the resistor to the primary side, the equivalent circuit is as follows Figure 10 As shown. Due to the compensation capacitor C 1 and L r Resonance, the system voltage and current phase diagram is as follows Figure 11 shown.

[0055] according to Figure 10 、 Figure 11 , the following relationships can be listed:

[0056]

[0057] According to the above formula, the DC side resistance R L-DC It can be calculated that:

[0058]

[0059] Obviously, only the initial current measurement of the SN system is required. I 1 and inverter output voltage U 1 to detect the load.

[0060] LCLN topology load identification solution:

[0061] By Thevenin's theorem, Figure 9 The circuit (b) is simplified to Figure 12 ,in U oc and X1 can be calculated by the following formula:

[0062]

[0063] according to Figure 12 , by taking the equivalent impedance X 1 and inductor Lr Resonance can achieve constant voltage output regardless of load. The primary side equivalent circuit and its voltage and current phase diagram are shown in the figure below. Figure 13 and Figure 14 shown.

[0064] Obviously, consistent with the SN topology, only the primary side current of the system needs to be I 1 and inverter output voltage U 1. The load can be identified by testing. The identification formula is as follows:

[0065] .

[0066] The proposed charging magnetic coupling mechanism for strong coupling includes two magnetic coupling mechanism designs. The appropriate magnetic coupling mechanism can be designed based on the specific performance requirements of the compact WPT system, and the proposed load identification method can be used to identify the system load.

Claims

1. A load identification method based on a strong coupling charging magnetic coupling mechanism, characterized in that: It includes a transmitting coil, a receiving coil and a ferrite; the coupling coefficient between the transmitting coil and the receiving coil is constant; a compensation capacitor is provided on the transmitting side C 1 and the primary side inductor L r , primary side inductance L r Obtained by the primary inductance when the primary is short-circuited; the receiving side has a load; by C 1 and primary side inductance L r Resonance achieves constant voltage output independent of load and enables calculation of load resistance; Compensation capacitor C 1 Primary-side inductance when the secondary is short-circuited L r After resonance, we get: in, ω is the system operating angular frequency, L m It is the transmitting coil L 1 Primary-side inductance when the secondary is short-circuited L r The difference between them, n is the transformation ratio of the ideal transformer in all main reference models, I Lm For inductance L m The current on R L-AC is the equivalent load on the AC side, U 1 is the AC voltage on the transmitting side, I 1 is the primary side current, I R AC equivalent load R L-AC The current on According to the above formula, the DC side resistance R L-DC Calculated: .

2. A load identification method based on a strong coupling charging magnetic coupling mechanism according to claim 1, characterized in that: Compensation capacitor C 1 Primary-side inductance when the secondary is short-circuited L r Connect in series, connected on the transmitting side; Calculate the operating angular frequency ω r : .

3. A charging magnetic coupling mechanism based on strong coupling, characterized in that: Load identification is performed by relying on a load identification method based on a strong coupling charging magnetic coupling mechanism as described in any one of claims 1-2; the ferrite is specifically a hollow cylinder, and the transmitting coil and the receiving coil are surrounded along the inner wall of the hollow cylindrical ferrite; the central axes of the ferrite, the transmitting coil and the receiving coil are located in the same straight line; the ferrite, the transmitting coil and the receiving coil are arranged from the outside to the inside.

4. A charging magnetic coupling mechanism based on strong coupling, characterized in that: Load identification is performed by relying on a load identification method based on a strong coupling charging magnetic coupling mechanism as described in any one of claims 1-2; the ferrite is specifically provided with a first ferrite and a second ferrite, the first ferrite is provided with a first annular groove, and the second ferrite is provided with a second annular groove; the first annular groove is used to place the receiving coil, and the second annular groove is used to place the transmitting coil.

5. The charging magnetic coupling mechanism based on strong coupling according to claim 4, characterized in that: The thickness of the receiving coil is consistent with the depth of the first annular groove; the thickness of the transmitting coil is consistent with the depth of the second annular groove.

6. The charging magnetic coupling mechanism based on strong coupling according to claim 4, characterized in that: The transmitting coil and the receiving coil are both wound with Litz wire.

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