Charging magnetic coupling mechanism based on strong coupling and load identification method thereof

Abstract

The invention provides a charging magnetic coupling mechanism based on strong coupling and a load identification method thereof. The charging magnetic coupling mechanism comprises a transmitting coil, a receiving coil and ferrite, the coupling coefficient of the transmitting coil and the receiving coil is constant; the transmitting side is provided with a capacitor and an inductor, and the inductor is obtained through a primary inductor during primary short circuit; the receiving side is provided with a load; through resonance of the capacitor and the inductor, constant voltage output irrelevant to the load is realized, and calculation of the load resistance is realized. And by accurately identifying the load, the requirement of a control strategy can be better met.

Description

Technical Field

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

[0002] Wireless Power Transfer (WPT) technology has significant advantages in terms of safety, convenience, and reliability due to its non-contact power transfer method. With the development of portable electronic devices, electric vehicles, and the Internet of Things (IoT), finding an efficient and portable charging solution has become an inevitable demand. Although traditional wired charging is mature in technology and low in cost, it is prone to generate sparks and fire hazards due to direct metal contact charging. Moreover, with the increase in electrical devices, using multiple power cords also brings inconvenience. Wireless charging has excellent characteristics such as large operating freedom, strong weather resistance, low maintenance cost, high safety, support for multi-device charging, convenience, and speed. It has great application potential in industrial fields such as electric vehicles, portable electronic products, biomedical devices, mineral extraction systems, and underwater applications.

[0003] Existing wireless charging systems use a traditional planar magnetic core structure, and their magnetic fields are distributed in a two-dimensional diffusion manner. During the charging process, the magnetic field energy is easily affected by position offset, and the magnetic field utilization rate is not high. Under high-frequency conditions, the problem of eddy current loss is prominent. Moreover, in a wireless charging system, the load is a key parameter affecting the output power and efficiency of the system. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a charging magnetic coupling mechanism based on strong coupling and a load identification method thereof. By accurately identifying the load, the requirements of the control strategy can be better met.

[0005] To achieve the above purpose, the present invention adopts the following technical solution: A load identification method for a charging magnetic coupling mechanism based on strong coupling, including a transmitting coil, a receiving coil, and a ferrite; the coupling coefficient between the transmitting coil and the receiving coil is constant; a capacitor and an inductor are provided on the transmitting side, and the inductor is obtained through the primary inductance when the primary side is short-circuited; the receiving side has a load; by resonating the capacitor and the inductor to achieve a constant voltage output independent of the load, the calculation of the load resistance is realized.

[0006] In a preferred embodiment, compensation capacitor C 1 and the primary side inductance when the secondary side is short-circuited L r are connected in series on the transmitting side; Calculate the working angular frequency ω r : 。

[0007] In a preferred embodiment, when the capacitor C 1 is short-circuited with the secondary, the primary-side inductance L r After resonance, we get: Wherein, ω is the angular frequency of system operation, L m is the transmitting coil L 1 and the primary-side inductance when the secondary is short-circuited L r is the difference between them, n is the turns ratio of the ideal transformer in all main reference models, I Lm is the inductance L m of 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 on the receiving side, I 1 is the primary-side current, I R is the AC equivalent load R L-AC of the current on, as Figure 9 shown; According to the above formula, the DC-side resistance R L-DC is calculated as: 。

[0008] The present invention also provides a charging magnetic coupling mechanism based on strong coupling, which performs load identification by relying on the load identification method of a charging magnetic coupling mechanism based on strong coupling; the ferrite is specifically a hollow cylindrical shape, and the transmitting coil and the receiving coil are wound along the inner wall of the hollow cylindrical ferrite; the central axes of the ferrite, the transmitting coil, and the receiving coil are located on the same straight line; the ferrite, the transmitting coil, and the receiving coil are arranged from outside to inside.

[0009] The present invention also provides a charging magnetic coupling mechanism based on strong coupling, which performs load identification by relying on the load identification method of a charging magnetic coupling mechanism based on strong coupling; 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.

[0010] 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.

[0011] In a preferred embodiment, both the transmitting coil and the receiving coil are wound with Litz wire.

[0012] Compared with the prior art, the present invention has the following beneficial effects: Through the composite structure design of the ferrite shell and the embedded coil, three-dimensional focusing of the spatial magnetic field is achieved.

[0013] (1) The coil gap matching physical plugging mechanism of Scheme 1 can not only avoid the arc generated by direct contact, but also achieve strong coupling and precise alignment. The integrated design of the embedded coil and the magnetic core in Scheme 2 reduces the volume of the mechanism, increases the power density, and enhances the magnetic field utilization rate.

[0014] (2) For the wired insertion type 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 the receiving side compensation can be removed by using the single-sided compensation topology, realizing the lightweight design of the wireless charging system.

[0015] (3) By using the charging coupling mechanism proposed in this paper, the problem of difficult identification caused by the coupling between the load and the mutual inductance can be solved, and the load can be accurately identified, so that the output power can be flexibly adjusted according to different loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the 3D model of the wired insertion type coupling mechanism of the preferred embodiment of the present invention; Figure 2 Schematic diagram of the cross-section along YOZ of the wired insertion type coupling mechanism of the preferred embodiment of the present invention; Figure 3 Schematic diagram of the application scenario of the insertion type coupling mechanism charging system of the preferred embodiment of the present invention; Figure 4 Schematic diagram of the 3D model of the compact coupling mechanism of the preferred embodiment of the present invention; Figure 5 Schematic diagram of the cross-section along YOZ of the compact coupling mechanism of the preferred embodiment of the present invention; Figure 6 Schematic diagram of the application scenario of the compact coupling mechanism wireless charging system of the preferred embodiment of the present invention; Figure 7 Schematic diagram of the SN topological structure of the wireless power transmission system of the preferred embodiment of the present invention; Figure 8 Schematic diagram of the LCLN topological structure of the wireless power transmission system of the preferred embodiment of the present invention; Figure 9All main reference models of the wireless power transfer system according to 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; Figure 10 Equivalent circuit diagram of the primary side of the SN system according to the preferred embodiment of the present invention; Figure 11 Voltage and current phase diagram of the SN system according to the preferred embodiment of the present invention; Figure 12 Simplified circuit diagram of the LCLN system according to the preferred embodiment of the present invention; Figure 13 Equivalent circuit diagram of the primary side of the LCLN system according to the preferred embodiment of the present invention; Figure 14 Voltage and current phase diagram of the LCLN system according to the preferred embodiment of the present invention. Detailed implementation manners

[0017] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] It should be noted that the following detailed description is exemplary and is 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 of ordinary skill in the technical field to which the present application belongs.

[0019] It should be noted that the terms used herein are only for describing specific implementation manners 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. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] The present invention proposes a charging coupling mechanism suitable for strong coupling. The coupling mechanism adopts a composite structure of a solenoid winding and a magnetic core, and is characterized by including: a ferrite shell made of high-permeability ferrite and an embedded coil structure. Each coupling mechanism realizes three-dimensional focusing of the spatial magnetic field through a specific winding arrangement and magnetic core gap matching.

[0021] First, the wired insertion type charging coupling mechanism proposed by the present invention is as Figure 1 shown. The transmitting device is a hollow cylinder structure. The system from the outside to the inside is respectively 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 embedded with a transmitting coil. The cross-section of the coupling mechanism along the YOZ parallel plane is as Figure 2As shown. The ferrite is specifically a hollow cylindrical shape, and the transmitting coil and the receiving coil are wound along the inner wall of the hollow cylindrical ferrite; the central axes of the ferrite, the transmitting coil, and the receiving coil are located on the same straight line; the ferrite, the transmitting coil, and the receiving coil are arranged from outside to inside.

[0022] The application scenarios of the charging system using this wired insertion type charging coupling mechanism are as Figure 3 shown. During the charging process, through physical plugging, the transmitting coil is sleeved outside the receiving coil for wireless charging. This charging method not only retains the usability of the traditional charging gun, can better achieve precise alignment, but also avoids the arc caused by direct contact, realizing the efficiency and safety of energy transmission. Since this design makes the distance between the transmitting coil and the receiving coil closer, the ferrite structure on the receiving side can be considered removed to achieve a lightweight design.

[0023] The wired insertion type contact charging scheme has gradually become a research hotspot in high-power scenarios due to both the physical certainty of traditional plugging and unplugging operations and the safety of wireless transmission. And the characteristic of not requiring full contact enables it to be better compatible with multiple vehicle models / devices compared with the traditional insertion structure. Through the insertion design, full contact is avoided, but there is mechanical guidance, which is more stable than traditional wireless charging. And through this design, the difficulty of alignment can be reduced to achieve stronger coupling. Since the insertion position is fixed and the coupling coefficient of the system is fixed, the coupling problems of the load and mutual inductance in parameter identification can be well avoided, reducing the difficulty of load identification.

[0024] The present invention further proposes a compact coupling mechanism, as Figure 4 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.

[0025] The first ferrite and the second ferrite are integrally formed of a high magnetic permeability ferrite material, having a disc-shaped structure, and concentric annular grooves are provided on the surface, and the groove depth matches the coil thickness.

[0026] Transmitting coil: Wound by Litz wire and embedded in the bottom layer of the ferrite groove.

[0027] Receiving coil: Wound by Litz wire and embedded in the upper layer of the ferrite groove. The cross-section of the coupling mechanism along the YOZ parallel plane is as Figure 5 shown.

[0028] The application scenarios of the compact coupling mechanism wireless charging system are as Figure 6As shown in the figure. During the charging process, the measurement module is used to move the transmitting device directly below the receiving device for charging. The ferrite base is used to wrap the transmitting / receiving coil to form a closed magnetic circuit, so that the magnetic induction lines are concentrated inside the groove, enhancing the coupling and improving the magnetic field utilization rate. This structure is applicable to wireless charging systems with strong coupling such as the SN topology.

[0029] The present invention proposes a load identification method for the above-mentioned magnetic coupling mechanism. The system in this article uses a single-sided compensation topology. By using a compensation network on the transmitting side, the weight on the receiving side is reduced. Taking the Series-None (S-N) topology and the Inductor-Capacitor-Inductor-None (LCL-N) as examples. The full-bridge inverter is adopted on the transmitting side, and the uncontrolled rectifier bridge is adopted on the receiving side. V INV ( V REC ) and U 1( U 2) represent 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.

[0030] SN topology load identification scheme: Replace the loose-coupling converter model in Figure 7 , 8 with all the main reference models to obtain Figure 9 , Figure 7 corresponding to Figure 9 (a), Figure 8 corresponding to Figure 9 (b). The parameters in the figure are shown in Equation (1).

[0031] According to Figure 9 (a), by resonating the capacitor C 1 with the inductor L r , a constant voltage output independent of the load is achieved. Among them, L r can be obtained as the primary inductance when the secondary is short-circuited.

[0032] In the formula, ω r is the system working angular frequency. Since the positions of the transmitting coil and the receiving coil are fixed and the mutual inductance is fixed when charging with the magnetic coupling mechanism of the present invention. Therefore, during the identification process, it is considered that L r in the figure, Lm is known. Equivalent the resistance to the primary side, the equivalent circuit is as Figure 10 shown. Due to the compensation capacitor C 1 and L r resonate, the voltage-current phase diagram of the system is as Figure 11 shown.

[0033] According to Figure 10 、 Figure 11 , the following relationship can be listed: According to the above formula, the DC-side resistance R L-DC can be calculated as: Obviously, only by detecting the primary-side current I 1 and the inverter output voltage U 1 of the SN system, the identification of the load can be realized.

[0034] LCLN topology load identification scheme: Through Thevenin's theorem, simplify the (b) circuit of Figure 9 to Figure 12 , where U oc and X1 can be calculated by the following formula: According to Figure 12 , by resonating the equivalent impedance X 1 with the inductor L r , the constant-voltage output independent of the load can be realized. The primary-side equivalent circuit and its voltage-current phase diagram are as Figure 13 and Figure 14 shown.

[0035] Obviously, consistent with the SN topology, only the primary-side current I 1 and the inverter output voltage U 1 of the system need to be detected to realize the identification of the load. The identification formula is as follows: .

[0036] The charging magnetic coupling mechanism applicable to strong coupling proposed by the present invention includes two magnetic coupling mechanism designs. The appropriate magnetic coupling mechanism can be designed according to 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 for a charging magnetic coupling mechanism based on strong coupling, 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 capacitor and an inductor are provided on the transmitting side, and the inductor is obtained through the primary inductance when the primary is short-circuited; the receiving side has a load; the constant voltage output independent of the load is achieved by resonating the capacitor and the inductor, and the calculation of the load resistance is realized.

2. The load identification method of a charging magnetic coupling mechanism based on strong coupling according to claim 1, wherein Compensation capacitor C Primary side inductance when 1 and the secondary are short-circuited L r Connected in series on the transmitting side; Calculate the working angular frequency ω r : 。 3. A load identification method for a charging magnetic coupling mechanism based on strong coupling according to claim 2, characterized in that, Capacitance C Primary-side inductance when 1 and the secondary are short-circuited L r After resonance, we get: Among them, ω is the system operating angular frequency, L m is the transmitting coil L the difference between the primary side inductance when 1 and the secondary side are short-circuited, n is the turns ratio of the ideal transformer in all main reference models, L r between, I Lm is the inductance L m the current on, R L-AC is the AC side equivalent load, U 1 is the AC voltage on the transmitting side, I 1 is the primary and secondary side current, I R is the AC equivalent load R L-AC the current on; According to the above formula, the DC-side resistance R L-DC Calculated as follows: 。 4. A charging magnetic coupling mechanism based on strong coupling, characterized in that, Load identification is performed by using a load identification method of a charging magnetic coupling mechanism based on strong coupling according to any one of claims 1-3; the ferrite is specifically a hollow cylindrical shape, and the transmitting coil and the receiving coil are wound along the inner wall of the hollow cylindrical ferrite; the central axes of the ferrite, the transmitting coil and the receiving coil are located on the same straight line; the ferrite, the transmitting coil and the receiving coil are arranged from outside to inside.

5. A charging magnetic coupling mechanism based on strong coupling, characterized in that Load identification is performed by using a load identification method of a charging magnetic coupling mechanism based on strong coupling according to any one of claims 1-3; 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.

6. The charging magnetic coupling mechanism based on strong coupling according to claim 5, 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.

7. A charging magnetic coupling mechanism based on strong coupling according to claim 5, characterized in that Both the transmitting coil and the receiving coil are wound with Litz wire.

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