A constant current and constant voltage switching wireless charging device and method based on a composite structure

Abstract

The application belongs to the technical field of electric vehicles, and relates to a constant-current constant-voltage switching wireless charging device and method based on a composite structure, which comprises a high-frequency full-bridge inverter circuit, a primary-side impedance matching network, a coupling coil, a secondary-side impedance matching network, a constant-current constant-voltage switching network and a rectifier circuit; the high-frequency full-bridge inverter circuit is connected with a constant-voltage source, the high-frequency full-bridge inverter circuit is connected with the primary-side impedance matching network, the primary-side impedance matching network is connected with the secondary-side impedance matching network through the coupling coil, the secondary-side impedance matching network is connected with the constant-current constant-voltage switching network, and the constant-current constant-voltage switching network is connected with a load through the rectifier circuit; the constant-current constant-voltage switching network comprises a constant-current capacitor, a constant-voltage capacitor and a switch, and the switching of the constant-current capacitor and the constant-voltage capacitor is realized through the opening and closing of the switch. The application uses one switch to meet the switching of the constant-current and constant-voltage modes under the condition that the system deviates, and the design method is simple and the output is stable.

Description

Technical Field

[0001] This invention relates to a constant current and constant voltage switching wireless charging device and method based on a composite structure, belonging to the field of electric vehicle technology, and particularly to electric vehicle charging technology. Background Technology

[0002] Currently, electric vehicles are considered an ideal mode of transportation to solve energy and emissions problems, and they can be charged using both wired and wireless power transfer technologies. Wired charging is the most common charging method for electric vehicles, but charging cables pose risks of tripping circuit breakers and electric shock, making them unsuitable for use in inclement weather conditions such as snow and ice. In contrast, wireless power transfer technology, which separates the primary and secondary sides, is convenient and reliable, and has seen rapid development in recent years.

[0003] For vehicles charging while stationary, the misalignment between coupling coils caused by parking position leads to increased system leakage inductance and a decreased coupling coefficient k, thus reducing system performance. Meanwhile, to extend battery life and cycle life, vehicle batteries are initially charged in constant current mode, then rapidly increased to a specified voltage level before switching to constant voltage mode. Therefore, ensuring efficient and stable switching between constant current and constant voltage charging modes during wireless charging, while maintaining a relatively large offset tolerance, is crucial for battery protection and enhanced safety.

[0004] Existing technologies combine two coupled structures with opposite output change trends during offset, allowing the changes in total output voltage or current to cancel each other out within a certain range, thus achieving a constant output independent of the load. Based on this characteristic, to achieve constant current and constant voltage switching, invention patent CN109617190A, "An Offset-Resistant Wireless Charging System Based on Constant Current-Constant Voltage Composite Topology," proposes a composite structure combining S-LCC and LCC-S topologies to achieve offset resistance. This scheme uses three switches to switch between constant current and constant voltage modes, increasing system complexity and design difficulty. Invention patent CN112865338A, "A Constant Current and Constant Voltage Offset-Resistant Output Wireless Charging System and Charging Method," proposes a composite structure combining LCC-LCC and SS topologies to overcome output instability. This scheme uses two switches and a series of components to switch charging modes, increasing system design cost and complexity.

[0005] In addition, some studies have explored switching between constant current and constant voltage modes by frequency conversion or duty cycle adjustment. However, these solutions require wide-range modulation techniques and complex control circuits. Primary-side-based control schemes, in particular, require stable communication methods, further increasing circuit complexity. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a constant current and constant voltage switching wireless charging device and method based on a composite structure. It utilizes a single switch to switch between constant current and constant voltage modes under system offset conditions, and the design method is simple and the output is stable.

[0007] To achieve the above objectives, the present invention proposes the following technical solution: a constant current / constant voltage switching wireless charging device based on a composite structure, comprising: a high-frequency full-bridge inverter circuit, a primary-side impedance matching network, a coupling coil, a secondary-side impedance matching network, a constant current / constant voltage switching network, and a rectifier circuit; the high-frequency full-bridge inverter circuit is connected to a constant voltage source, the high-frequency full-bridge inverter circuit is connected to the primary-side impedance matching network, the primary-side impedance matching network is connected to the secondary-side impedance matching network via the coupling coil, the secondary-side impedance matching network is connected to the constant current / constant voltage switching network, and the constant current / constant voltage switching network is connected to the load via the rectifier circuit; the constant current / constant voltage switching network includes a constant current capacitor, a constant voltage capacitor, and a switch, and the switching between the constant current capacitor and the constant voltage capacitor is realized by opening and closing the switch.

[0008] Furthermore, the coupling coil includes a first inductor, a second inductor, a third inductor, and a fourth inductor, wherein the first inductor and the third inductor are connected to the primary impedance matching network, and the second inductor and the fourth inductor are connected to the secondary impedance matching network.

[0009] Furthermore, the first and third inductors are connected in series, and the second and fourth inductors are connected in parallel.

[0010] Furthermore, the primary-side impedance matching network includes a first capacitor, a third capacitor, and a sixth capacitor. The input terminal of the first capacitor is connected to a high-frequency full-bridge inverter circuit. The first capacitor is connected in series with the first inductor, the third capacitor, and the third inductor in sequence. The output terminal of the third inductor is connected to the high-frequency full-bridge inverter circuit. The sixth capacitor is connected in parallel with the third capacitor and the third inductor.

[0011] Furthermore, the secondary impedance matching network includes a second capacitor, a fourth capacitor, a fifth capacitor, and a fifth inductor, wherein the second capacitor is connected in series with the second and fifth inductors, the fourth capacitor is connected in series with the fourth inductor, and the fifth capacitor is connected in parallel with the second inductor and the second capacitor.

[0012] Furthermore, the constant current and constant voltage switching network includes a constant voltage capacitor, a constant current capacitor, a switch, a sixth inductor, and a seventh inductor. The constant voltage capacitor and the constant current capacitor are connected in parallel and intersect at two connection points. One connection point is connected to the secondary impedance matching network through the sixth inductor and to the rectifier circuit through the seventh inductor. The other connection point is connected to both the secondary impedance matching network and the rectifier circuit. The switch is connected in series with the constant voltage capacitor.

[0013] Furthermore, the primary-side impedance matching network includes a primary-side S-type impedance matching network and a primary-side T-type impedance matching network, and the first capacitor is the compensation capacitor C of the primary-side S-type impedance matching network. X Compensating inductor L of the primary-side T-type impedance matching network X The equivalent device, the impedance of the first capacitor satisfies the following equation:

[0014]

[0015] in, It is the impedance of the first capacitor. It is the compensation capacitor C X impedance, It is the compensating inductor L X The impedance.

[0016] This invention also discloses a constant current / constant voltage switching wireless charging method based on a composite structure, employing any of the aforementioned constant current / constant voltage switching wireless charging devices based on a composite structure, comprising the following steps: analyzing the output characteristics of the composite structure to obtain a constant output that is independent of the load and under a preset offset; based on the constant output, analyzing the characteristics of the constant current / constant voltage switching network to obtain the voltage or current gain of the constant current mode and the constant voltage mode; adjusting parameters, combining the voltage or current gain of the constant current capacitor and the constant voltage capacitor, to make the composite structure output constant voltage within a preset gain deviation Δ range, and completing the conversion from constant current mode to constant voltage mode under the action of a switch.

[0017] Furthermore, the method for obtaining the voltage or current gain in constant current mode and constant voltage mode is as follows: the constant current / constant voltage switching network is a reconfigurable topology. When switch S is open, the reconfigurable topology operates in constant current mode, and the current gain is G. CC =-jωC C When switch S is closed, the reconfigurable topology operates in constant voltage mode with a voltage gain of G. CV =1; When switch S is open, the current gain G of the wireless power transfer device is 1. VI for:

[0018]

[0019] When switch S is closed, the voltage gain of the wireless power transmission device is G. VV :

[0020]

[0021] Where ω is the angular frequency, C C For constant current resistor, j is the imaginary number, M 12 It is the mutual inductance between the first inductor and the second inductor, M 34L5 is the mutual inductance between the third and fourth inductors, and L6 is the fifth inductor. X The compensating inductor L of the primary-side T-type impedance matching network X The impedance.

[0022] Furthermore, the method for switching from constant current mode to constant voltage mode is as follows: switch S is open, charging is performed in constant current mode, and the battery voltage is monitored by the secondary control system; it is determined whether the charging mode needs to be switched, and if so, proceed to the next step; the current of the switch branch is monitored to determine whether it is zero, if it is not zero, monitoring continues, if it is zero, proceed to the next step; switch S is closed, and it is checked whether switch S is actually closed, if not, return to the previous step, if so, charging begins in constant voltage mode.

[0023] The present invention has the following advantages due to the adoption of the above technical solutions:

[0024] 1. In the event of a displacement of the inductor coil in a wireless charging system, this invention can achieve a constant gain within an acceptable range, independent of the load, through an impedance matching network between the primary and secondary sides, thereby improving the stability and robustness of the system.

[0025] 2. The constant current and constant voltage switching circuit can switch the system output mode by switching control. This switching circuit does not require auxiliary communication between the primary and secondary sides, nor does it require the addition of additional frequency and phase modulation control circuits, which reduces the complexity of the system and reduces manufacturing costs.

[0026] 3. The entire system uses only one switching device, and the circuit components have been optimized to avoid power loss caused by too many switches or components, simplifying the system design and improving the overall efficiency of the system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a constant current and constant voltage switching wireless charging device based on a composite structure in one embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of a composite structure with primary sides connected in series and secondary sides connected in parallel in one embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of a constant current and constant voltage switching network in one embodiment of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the specific embodiments are provided only for a better understanding of the present invention and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] To address the issues of requiring wide-range modulation techniques and complex control circuits in existing technologies, this invention proposes a constant-current / constant-voltage switching wireless charging device and method based on a composite structure. The device includes a high-frequency full-bridge inverter circuit, a primary-side impedance matching network, a coupling coil, a secondary-side impedance matching network, a constant-current / constant-voltage switching network, and a rectifier circuit. This system utilizes only a single switch S, satisfying the switching between constant-current and constant-voltage modes even under system offset. Furthermore, the design method is simple, and the output is stable. The technical solution of this invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0032] Example 1

[0033] This embodiment discloses a constant current and constant voltage switching wireless charging device based on a composite structure, such as... Figure 1 As shown, the device includes: a high-frequency full-bridge inverter circuit, a primary-side impedance matching network, a coupling coil, a secondary-side impedance matching network, a constant-current / constant-voltage switching network, and a rectifier circuit. The high-frequency full-bridge inverter circuit is connected to a constant voltage source and the primary-side impedance matching network. The primary-side impedance matching network is connected to the secondary-side impedance matching network via the coupling coil. The secondary-side impedance matching network is connected to the constant-current / constant-voltage switching network, which is connected to the load via the rectifier circuit. The constant-current / constant-voltage switching network includes a constant-current capacitor C. C Constant voltage capacitor C V And switch S, by opening and closing switch S, the constant current capacitor C is realized. C and constant voltage capacitor C V Switching.

[0034] The coupling coil includes a first inductor L1, a second inductor L2, a third inductor L3, and a fourth inductor L4. The first inductor L1 and the third inductor L3 are connected to the primary impedance matching network, and the second inductor L2 and the fourth inductor L4 are connected to the secondary impedance matching network. The first inductor L1 and the third inductor L3 are connected in series, and the second inductor L2 and the fourth inductor L4 are connected in parallel. Figure 1 M 12 It is the mutual inductance between the first inductor L1 and the second inductor L2, M 13 It is the mutual inductance between the first inductor L1 and the third inductor L3, M 14 It is the mutual inductance between the first inductor L1 and the fourth inductor L4, M 23 It is the mutual inductance between the second inductor L2 and the third inductor L3; M24 It is the mutual inductance between the second inductor L2 and the fourth inductor L4; M 34 It is the mutual inductance between the third inductor L3 and the fourth inductor L4.

[0035] The primary-side impedance matching network includes a first capacitor C1, a third capacitor C3, and a sixth capacitor C6. The input terminal of the first capacitor C1 is connected to a high-frequency full-bridge inverter circuit. The first capacitor C1 is connected in series with the first inductor L1, the third capacitor C3, and the third inductor L3 in sequence. The output terminal of the third inductor L3 is connected to the high-frequency full-bridge inverter circuit. The sixth capacitor C6 is connected in parallel with the third capacitor C3 and the third inductor L3.

[0036] The primary-side impedance matching network includes a primary-side S-impedance matching network and a primary-side T-type impedance matching network. The first capacitor C1 is the compensation capacitor C of the primary-side S-impedance matching network. X Compensating inductor L of the primary-side T-type impedance matching network X The equivalent device, the impedance of the first capacitor C1, satisfies the following equation:

[0037]

[0038] in, It is the impedance of the first capacitor C1. It is the compensation capacitor C X impedance, It is the compensating inductor L X The impedance.

[0039] like Figure 2 As shown, the primary-side impedance matching network includes a first compensation device X1, a third compensation device X3, a seventh compensation device X7, and an eighth compensation device X8; the coupling coil includes a first inductor L1, a second inductor L2, a third inductor L3, and a fourth inductor L4; and the secondary-side impedance matching network includes a second compensation device X2, a fourth compensation device X4, a fifth compensation device X5, and a sixth compensation device X6. The primary-side impedance matching network, the coupling coil, and the secondary-side impedance matching network constitute a composite structure with the primary side connected in series and the secondary side connected in parallel. The first compensation device X1 and the first inductor L1 form a primary-side S-type impedance matching network with an equivalent impedance of Z1. The third compensation device X3, the seventh compensation device X7, the eighth compensation device X8, and the third inductor L3 form the three arms of the primary-side T-type impedance matching network, with the equivalent impedance of each arm of the primary-side T-type impedance matching network having a magnitude of Z3. The second compensation device X2, the fourth compensation device X4, the sixth compensation device X6, and the second inductor L2 form the three arms of the secondary-side T-type impedance matching network, with the equivalent impedance of each arm of the secondary-side T-type impedance matching network having a magnitude of Z2. The fourth compensation device X4 and the fourth inductor L4 form the secondary-side S-type impedance matching network with an equivalent impedance of Z4. in I is the input voltage with angular frequency ω. inFor the output current, R EF For the equivalent load, U EF and I EF Equivalent load R EF The voltage and current at both ends, Z M_12 Z is the mutual impedance between the first inductor L1 and the second inductor L2. M_34 Let L3 be the mutual impedance between the third inductor and the fourth inductor L4. Based on the characteristics of the DDQ coil, the mutual inductance between the first inductor L1 and the second inductor L2, the mutual inductance between the first inductor L1 and the fourth inductor L4, the mutual inductance between the third inductor L3 and the second inductor L2, and the mutual inductance between the second inductor L2 and the fourth inductor L4 can be ignored.

[0040] The secondary impedance matching network includes a second capacitor C2, a fourth capacitor C4, a fifth capacitor C5, and a fifth inductor L5. The second capacitor C2 is connected in series with the second inductor L2 and the fifth inductor L5, the fourth capacitor C4 is connected in series with the fourth inductor L4, and the fifth capacitor C5 is connected in parallel with the second inductor L2 and the second capacitor C2.

[0041] like Figure 3 As shown, the constant current / constant voltage switching network includes a constant voltage capacitor C. V Constant current capacitor C C Switch S, sixth inductor L L and the seventh inductor L C Constant voltage capacitor C V and constant current capacitor C C The circuits are connected in parallel and intersect at two connection points, one of which is through the sixth inductor L. L Connected to the secondary impedance matching network; via the seventh inductor L C One connection point is connected to the rectifier circuit; the other connection point is connected to both the secondary impedance matching network and the rectifier circuit. Switch S is connected to the constant voltage capacitor C. V Series connection.

[0042] Example 2

[0043] Based on the same inventive concept, this embodiment discloses a constant current and constant voltage switching wireless charging method based on a composite structure, employing any of the aforementioned constant current and constant voltage switching wireless charging devices based on a composite structure, including the following steps:

[0044] S1 analyzes the output characteristics of the composite structure to obtain its output which is independent of the load and constant under a preset offset;

[0045] Based on a constant output, S2 analyzes the characteristics of the constant current / constant voltage switching network to obtain the voltage or current gain in constant current mode and constant voltage mode.

[0046] The method for obtaining the voltage or current gain in constant current and constant voltage modes is as follows: the constant current / constant voltage switching network is a reconfigurable topology. When switch S is open, the reconfigurable topology operates in constant current mode, and the current gain is G. CC =-jωC C When switch S is closed, the reconfigurable topology operates in constant voltage mode with a voltage gain of G. CV =1; When switch S is open, the current gain G of the wireless power transfer device is 1. VI for:

[0047]

[0048] When switch S is closed, the voltage gain of the wireless power transmission device is G. VV :

[0049]

[0050] Where ω is the angular frequency, C C For constant current resistor, j is the imaginary number, M 12 It is the mutual inductance between the first inductor L1 and the second inductor L2, M 34 It is the mutual inductance between the third inductor L3 and the fourth inductor L4, and L5 is the fifth inductor. X The compensating inductor L of the primary-side T-type impedance matching network X The impedance.

[0051] According to Kirchhoff's laws, the voltage gain of the composite structure can be calculated as follows:

[0052]

[0053] The results show that the output voltage of this hybrid topology is independent of the load, and when the coil is misaligned, Z M_12 and Z M_34 Decrease, leading to Z M_12 / Z2 decreases, Z3 / Z M_34 Increase. If the parameters are chosen appropriately, this can be achieved by offsetting Z. M_12 and Z M_34 The effect of increase or decrease, voltage gain G V It can remain constant within a certain range.

[0054] The equivalent input impedance can be:

[0055]

[0056] Based on the input impedance, it can be determined that this is a pure resistor, and the current and voltage can achieve zero phase (ZPA).

[0057] like Figure 3 As shown, the sixth inductor LL Seventh inductor L C Constant current capacitor C C Constant voltage capacitor C V Together with switch S, they form a reconfigurable topology that enables the charging mode to switch from constant current to constant voltage. Capacitor C... Z For constant current capacitor C C and constant voltage capacitor C V The equivalent capacitance after parallel connection. In a reconfigurable topology, the impedances of the various components have the following relationship;

[0058]

[0059] When switch S is open, the circuit operates in constant current mode, and the current gain of the reconfigurable topology is...

[0060]

[0061] When switch S is closed, the circuit operates in constant voltage mode, and the voltage gain of the reconfigurable topology is:

[0062]

[0063] Will Figure 2 The composite structure in Figure 3 By combining reconfigurable topologies, we can obtain, for example... Figure 1 The complete circuit shown is illustrated, where the first capacitor C1 is the equivalent capacitance of the first compensation device X1 and the seventh compensation device X7, and the first compensation device X1 is the capacitor C. X The seventh compensation device X7 is the compensation inductor L. X .

[0064] When switch S is open, the circuit operates in constant current mode, and the current gain of the complete circuit is:

[0065]

[0066] When switch S is closed, the circuit operates in constant voltage mode, and the voltage gain of the complete circuit is:

[0067]

[0068] In the complete circuit, the voltage of the constant voltage source is and the current across the load is I. L and voltage U L It can be represented as:

[0069]

[0070] Based on the coil's offset characteristics, when the coil offsets, M 12 and M 34They exhibit a linear relationship within a certain range, and this relationship can be expressed as follows:

[0071] M 12 =aM 34 +b (9)

[0072] S3 adjustment parameter, combined with constant current capacitor C C and constant voltage capacitor C V The voltage or current gain enables the composite structure to output a constant voltage within a preset gain deviation Δ range, and the constant current mode to constant voltage mode is switched under the action of switch S.

[0073] The process of adjusting the parameters is as follows:

[0074] The value of the fifth inductance L5 of the primary-side T-type impedance matching network is determined by equation (10):

[0075]

[0076] in,

[0077] Compensating inductor L X The value is determined by equation (11):

[0078]

[0079] The values ​​of the second capacitor C2 and the fifth capacitor C5 can be determined by equation (12):

[0080]

[0081] The values ​​of the third capacitor C3 and the sixth capacitor C6 can be determined by equation (13):

[0082]

[0083] The compensation capacitor C of the primary-side S-impedance matching network X The value can be determined by equation (14):

[0084]

[0085] The value of the first capacitor C1 can be determined by equation (15):

[0086]

[0087] The value of the fourth capacitor C4 can be determined by equation (16):

[0088]

[0089] Constant current capacitor C C The value can be determined by equation (14):

[0090]

[0091] Sixth inductor L L Seventh inductor L C and constant current capacitor C V The value of can be determined by equation (3).

[0092] The method for switching from constant current mode to constant voltage mode is as follows: switch S is open, charging is performed in constant current mode, and the battery voltage is monitored by the secondary control system; it is determined whether the charging mode needs to be switched, and if so, proceed to the next step; the current in the switch branch is monitored to determine if it is zero, and if it is not zero, monitoring continues, and if it is zero, proceed to the next step; switch S is closed, and it is checked whether switch S is actually closed, and if not, return to the previous step, and if so, charging begins in constant voltage mode.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific embodiments of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention. The above content is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A composite structure-based constant current and constant voltage switching wireless charging device, characterized by, The application relates to a composite structure-based constant-current constant-voltage switching wireless charging device. The high-frequency full-bridge inverter circuit is connected with a constant-voltage source, the high-frequency full-bridge inverter circuit is connected with a primary-side impedance matching network, the primary-side impedance matching network is connected with a secondary-side impedance matching network through a coupling coil, the secondary-side impedance matching network is connected with a constant-current constant-voltage switching network, and the constant-current constant-voltage switching network is connected with a load through a rectifier circuit. The constant-current constant-voltage switching network comprises a constant-current capacitor, a constant-voltage capacitor and a switch, the constant-current capacitor and the constant-voltage capacitor are connected in parallel, the switch is connected in series with the constant-voltage capacitor, and the opening and closing of the switch can realize the switching of the constant-current and constant-voltage charging modes. The constant-current constant-voltage switching network further comprises a sixth inductor and a seventh inductor, the constant-voltage capacitor and the constant-current capacitor are connected in parallel and intersect at two connection points, one of the connection points is connected with the secondary-side impedance matching network through the sixth inductor and is connected with the rectifier circuit through the seventh inductor, and the other connection point is connected with the secondary-side impedance matching network and the rectifier circuit respectively. When the switch is open, the circuit operates in a constant-current mode, and the current gain of the complete circuit is: When the switch is closed, the circuit operates in a constant-voltage mode, and the voltage gain of the complete circuit is: The coupling coil comprises a first inductor, a second inductor, a third inductor and a fourth inductor, wherein the first inductor and the third inductor are connected with the primary-side impedance matching network, the second inductor and the fourth inductor are connected with the secondary-side impedance matching network, the first inductor and the third inductor are connected in series, and the second inductor and the fourth inductor are connected in parallel. wherein The secondary-side impedance matching network comprises a second capacitor, a fourth capacitor, a fifth capacitor and a fifth inductor, wherein the second capacitor is connected in series with the second inductor and the fifth inductor, the fourth capacitor is connected in series with the fourth inductor, and the fifth capacitor is connected in parallel with the second inductor and the second capacitor. is an angular frequency ， is a constant current capacitor, is a sign of imaginary number, M 12 is a mutual inductance of the first inductance and the second inductance, M 34 is a mutual inductance of the third inductance and the fourth inductance, is a fifth inductance, is a compensation inductance of the primary side T-type impedance matching network L X is an impedance of the The primary-side impedance matching network comprises a first capacitor, a third capacitor and a sixth capacitor, wherein the input end of the first capacitor is connected with the high-frequency full-bridge inverter circuit, the first capacitor is connected in series with the first inductor, the third capacitor and the third inductor in sequence, the output end of the third inductor is connected with the high-frequency full-bridge inverter circuit, and the sixth capacitor is connected in parallel with the third capacitor and the third inductor. The application further discloses a method for obtaining the voltage or current gain of the constant-current mode and the constant-voltage mode.

2. The composite structure based constant current and constant voltage switching wireless charging device of claim 1, wherein, The application further discloses a method for obtaining the voltage or current gain of the constant-current mode and the constant-voltage mode.

3. The composite structure based constant current and constant voltage switching wireless charging device of claim 1, wherein, The primary-side impedance matching network comprises a primary-side S impedance matching network and a primary-side T-type impedance matching network, and the first capacitor is a compensation capacitor of the primary-side S impedance matching network C X and a compensation inductor of the primary-side T-type impedance matching network L X An impedance of the first capacitor satisfies the following formula: wherein is the impedance of the first capacitor, is the compensation capacitor C X is the impedance of the first capacitor, is the compensation inductor L X is the impedance of the first capacitor.

4. A constant current and constant voltage switching wireless charging method based on a composite structure, characterized by, The application further discloses a method for obtaining the voltage or current gain of the constant-current mode and the constant-voltage mode. When the switch is open, the circuit operates in a constant-current mode, and the current gain of the complete circuit is: When the switch is closed, the circuit operates in a constant-voltage mode, and the voltage gain of the complete circuit is: The adjusting parameter combines the voltage or current gain of the constant current capacitor and the constant voltage capacitor, so that the composite structure outputs constant voltage within a preset gain deviation and completes the switching from constant current mode to constant voltage mode under the action of the switch.

5. The composite structure based constant current and constant voltage switching wireless charging method of claim 4, wherein, ​ The constant-current constant-voltage switching network is a reconfigurable topology, when the switch S is open, the reconfigurable topology works in a constant-current mode, and a current gain is ; when the switch S is closed, the reconfigurable topology works in a constant-voltage mode, and a voltage gain is . ​ ​ wherein ​ is the angular frequency ， is a constant current resistance, is the imaginary unit, M 12 is the mutual inductance of the first and second inductances, M 34 is the mutual inductance of the third and fourth inductances, is the fifth inductance, is the compensation inductance of the primary side T-type impedance matching network L X the impedance of the.

6. The composite structure based constant current and constant voltage switching wireless charging method of claim 5, wherein, The method for completing the switch from constant current mode to constant voltage mode is: switch S is opened, charging in constant current mode, monitoring battery voltage through control system of secondary side; judging whether the charging mode needs to be switched, if yes, going to next step; monitoring current of switch branch, judging whether it is zero, if not, continuing to monitor, if yes, going to next step; closing switch S, checking whether switch S is actually closed, if not, returning to previous step, if yes, starting charging in constant voltage mode.

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