Wireless power transfer system with dual voltage level output and switching method thereof

Abstract

This application provides a wireless power transfer system with dual voltage level output and its switching method to solve the problem that existing WPT systems cannot meet the charging needs of different voltage levels. It includes a transmitting unit and a receiving unit. The transmitting unit includes a DC power supply, a high-frequency inverter, and a transmitting coil circuit connected in sequence. The transmitting coil circuit is connected in sequence to a first transmitting coil, a first primary-side resonant capacitor, a control switch, a second primary-side resonant capacitor, and a second transmitting coil. The other ends of both the first and second transmitting coils are connected to the output terminal of the high-frequency inverter. A switching circuit is also provided between the first and second transmitting coils to cooperate with the control switch to enable the system to switch between dual voltage levels. This application achieves the switching between different voltage levels through the control of the control switch and the switching circuit, thus meeting the charging needs of different voltage levels.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission, and in particular to a wireless power transmission system with dual voltage level output and its switching method. Background Technology

[0002] With the rapid development of electronic devices such as electric vehicles, drones, mobile robots, and implantable medical devices, traditional wired power supply methods have gradually revealed many limitations in terms of security, flexibility, and reliability. Wireless power transfer (WPT) technology, which enables contactless power transfer through electromagnetic fields, provides a safer, more convenient, and highly reliable power supply method for devices, and has therefore attracted widespread attention. Among them, magnetically coupled resonant wireless power transfer (MC-WPT) technology features high transmission efficiency, high power levels, and good system stability, and is widely used in wireless charging of electric vehicles, wireless power supply for drones, and charging of consumer electronic devices.

[0003] In practical applications, different load devices often require different output voltage levels. For example, a system may need high-voltage or low-voltage power supply during startup, fast charging, or different operating modes. Therefore, how to flexibly adjust the output voltage level of a wireless power transfer system while ensuring stable operation and high efficiency has become an important research issue. Meanwhile, the resonant compensation network, as a crucial component of the MC-WPT system, has a key impact on the system's power transfer capability, output characteristics, and operational stability. Therefore, researching a resonant compensation topology and its tuning method that can flexibly switch between different operating modes and achieve stable output at different voltage levels has significant research importance and engineering value. Summary of the Invention

[0004] The purpose of this invention is to provide a wireless power transfer system with dual voltage level output and its switching method. This addresses the technical problem that existing WPT systems cannot meet the charging requirements of different voltage levels.

[0005] First, this application provides a wireless power transmission system with dual voltage level output, including a transmitting unit and a receiving unit. The transmitting unit includes a DC power supply, a high-frequency inverter and a transmitting coil circuit connected in sequence.

[0006] The transmitting coil circuit is sequentially connected to the first transmitting coil, the first primary resonant capacitor, the control switch, the second primary resonant capacitor, and the second transmitting coil. The other ends of the first transmitting coil and the second transmitting coil are both connected to the output terminal of the high-frequency inverter. A switching circuit is also provided between the first transmitting coil and the second transmitting coil to cooperate with the control switch to enable the system to switch between two voltage levels.

[0007] Optionally, the switching circuit includes a primary-side resonant inductor, a third primary-side resonant capacitor, and a plate capacitor;

[0008] One end of the primary resonant inductor and the third primary resonant capacitor are connected to the input and output terminals of the control switch, respectively. The other end of the primary resonant inductor and the third primary resonant capacitor is connected to the other end of the second transmitting coil. The two ends of the plate capacitor are connected to the other end of the first transmitting coil and one end of the primary resonant inductor, respectively. When the two plates of the plate capacitor are parallel and facing each other, the plate capacitor is connected to the system. When the two plates of the plate capacitor are perpendicular, the plate capacitor is disconnected from the system.

[0009] Optionally, the first transmitting coil and the second transmitting coil are wound in opposite directions.

[0010] Optionally, when the control switch is closed, the two plates of the plate capacitor are perpendicular, and the primary resonant inductor, the third primary resonant capacitor, and the plate capacitor are disconnected from the system.

[0011] Optionally, when the control switch is off, the two plates of the plate capacitor are parallel and facing each other.

[0012] The second primary-side resonant capacitor, the third primary-side resonant capacitor, and the second transmitting coil are connected in series to form a relay circuit. The first primary-side resonant capacitor, the plate capacitor, and the primary-side resonant inductor constitute the LCC compensation circuit of the first transmitting coil.

[0013] Optionally, the receiving unit includes a receiving coil, a secondary-side compensation circuit, a rectifier, and a load connected in sequence, wherein the secondary-side compensation circuit is an LCC topology.

[0014] Optionally, the plate capacitor includes a base plate and a drive motor, as well as a first housing and a second housing rotatably mounted at one end;

[0015] The first housing and the drive motor are mounted on the base plate. The two plates of the plate capacitor are respectively embedded in the first housing and the second housing. The output shaft of the servo motor is connected to the rotating shaft of the second housing. The servo motor is used to drive the second housing and the embedded plates to rotate.

[0016] Secondly, this application provides a switching method for a wireless power transmission system with dual voltage level output, employing the aforementioned wireless power transmission system with dual voltage level output. The specific steps are as follows:

[0017] S1: Collect WPT system circuit parameters and set two wireless charging levels: high voltage and low voltage.

[0018] S2: Obtain the wireless charging voltage required by the receiving unit;

[0019] S3: Match the wireless charging level and control the switching of the control switch and plate capacitor according to the wireless charging voltage required by the receiving unit.

[0020] Optionally, when the wireless charging voltage required by the receiving unit is a high voltage level, the control switch is closed, and the two plates of the electrode capacitor are arranged vertically; when the wireless charging voltage required by the receiving unit is a low voltage level, the control switch is open, and the two plates of the electrode capacitor are arranged parallel and facing each other.

[0021] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0022] This application utilizes a rotatable plate capacitor and a control switch. When the control switch is closed and the two plates of the plate capacitor are vertically aligned, the WPT system operates in an S-LCC topology, achieving constant voltage output at a high voltage level. When the control switch is open and the two plates of the plate capacitor are parallel and facing each other, the WPT system operates in an LCC-S-LCC topology containing a single passive coil, achieving constant voltage output at a low voltage level. This allows for switching between different voltage levels, meeting the charging requirements of different voltage levels.

[0023] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0024] The accompanying drawings of this invention are described below.

[0025] Figure 1 This is a circuit diagram of the wireless power transmission system with dual voltage level output of the present invention.

[0026] Figure 2 This is a circuit diagram of the system of the present invention when it is an S-LCC topology.

[0027] Figure 3 This is a circuit diagram of the system of the present invention when the topology is LCC-S-LCC.

[0028] Figure 4 This is a schematic diagram of the structure of the plate capacitor of the present invention.

[0029] Figure 5 This is a schematic diagram of the coupling mechanism of the present invention.

[0030] Figure 6 This is a graph showing the change of system output voltage with load when S1 is closed and the two plates of the capacitor are perpendicular.

[0031] Figure 7 This is a graph showing the change in system output voltage with load when S1 is disconnected and the two plates of the plate capacitor are parallel and facing each other.

[0032] In the diagram: 1-base plate; 2-first housing; 3-second housing; 4-polar plate; 5-servo motor. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments. The terms "vertical," "horizontal," "inner," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" or "linked" should be interpreted broadly, for example, it can be a fixed connection, a detachable connection, an integral connection, an electrical connection, or a signal connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0034] Example 1:

[0035] like Figure 1 The wireless power transmission system shown includes a transmitting unit and a receiving unit, wherein the transmitting unit includes a DC power supply connected in sequence. High-frequency inverter and transmitting coil circuit;

[0036] The transmitting coil circuit is connected in sequence to the first transmitting coil. First primary resonant capacitor Control switch Second primary resonant capacitor Second transmitting coil The first transmitting coil Second transmitting coil The winding directions are opposite, the first transmitting coil Second transmitting coil The other end of each is connected to the output terminal of the high-frequency inverter, and the first transmitting coil Second transmitting coil A switching circuit is also provided between the two voltage levels to work with the control switch.

[0037] The switching circuit includes a primary resonant inductor. Third primary resonant capacitor and plate capacitor The primary-side resonant inductor and the third primary resonant capacitor One end is connected to the control switch The input and output terminals are connected, and the primary resonant inductor is... and the third primary resonant capacitor The other end is connected to the second transmitting coil The other end is connected to the plate capacitor. The two ends are respectively connected to the first transmitting coil The other end and the primary resonant inductor One end is connected to the plate capacitor. When the two plates are parallel and facing each other, the plate capacitance Access system, the plate capacitor Plate capacitance when the two plates are perpendicular Disconnected from the system.

[0038] like Figure 1 The receiving unit includes receiving coils connected in sequence. Secondary-side compensation circuit, rectifier and load The secondary-side compensation circuit is an LCC topology, including a first secondary-side resonant capacitor. Secondary resonant capacitor and secondary resonant inductor .

[0039] In this embodiment, the high-frequency inverter is an H-type high-frequency inverter, including... Four MOSFETs; the rectifier is a full-bridge rectifier, including... Four diodes and filter capacitor .

[0040] As one embodiment of this application, such as Figure 4 As shown, the plate capacitor includes a base plate 1 and a drive motor 5, as well as a first housing 2 and a second housing 3 rotatably mounted at one end; the first housing 2 and the drive motor 5 are mounted on the base plate 1, and the two plates 4 of the plate capacitor are respectively embedded in the first housing 2 and the second housing 3. The output shaft of the servo motor 5 is connected to the rotating shaft of the second housing 3, and the servo motor 5 is used to drive the second housing 3 and its embedded plates to rotate. Wherein: Figure 4 (a) is a schematic diagram of the structure of the plate capacitor when the two plates 3 are arranged in parallel and facing each other. Figure 4 (b) is a schematic diagram of the plate capacitor structure when the two plates 3 are set vertically.

[0041] System analysis:

[0042] like Figure 2As shown, when the control switch Closed and plate capacitor The two plates are perpendicular, and the plate capacitance is... When the system is disconnected, the primary resonant inductor and the third primary resonant capacitor The impedance of a parallel resonant circuit is infinite, which is equivalent to an open circuit. Therefore, the equivalent circuit of the system is as follows: Figure 2 As shown, the WPT system operates in an S-LCC topology. According to Kirchhoff's voltage law, we have:

[0043] (1)

[0044] in, It is the resonant angular frequency. For the first transmitting coil and the first transmitting coil Mutual intuition For the first transmitting coil and receiving coil Mutual intuition For the first transmitting coil and receiving coil Mutual intuition , This is the inverter output voltage. The current flowing through the first transmitting coil, The current flowing through the second transmitting coil, This is the current flowing through the receiving coil.

[0045] Define the impedance of the receiver unit CL network as:

[0046] (2)

[0047] When the system is in a resonant state, the relationship between the capacitors and inductors can be expressed as:

[0048] (3)

[0049] Substituting equation (3) into equation (1) for further derivation, we get:

[0050] (4)

[0051] (5)

[0052] From equation (5), it can be seen that when the control switch Closed and plate capacitor When the two plates are perpendicular, the system output voltage Equivalent resistance of load It is irrelevant; therefore, the system can achieve constant current output.

[0053] like Figure 3 As shown, when the control switch Disconnected and plate capacitor The two plates are arranged parallel to each other, and the second primary resonant capacitor Third primary resonant capacitor Second transmitting coil The series connection forms a relay circuit, and the first primary-side resonant capacitor Plate capacitors and primary resonant inductor Construct the first transmitting coil The LCC compensation circuit; according to Kirchhoff's voltage law, we get:

[0054] (6)

[0055] When all networks in the system are in a resonant state, the relationship between the capacitors and inductors can be expressed as:

[0056] (7)

[0057] Substituting equation (7) into equation (6) for further derivation, we can obtain the expressions for the currents of each coil as follows:

[0058] (8)

[0059] (9)

[0060] From equation (9), it can be seen that when the control switch Disconnected and plate capacitor When the two plates are parallel and facing each other, and all coils in the system are in a resonant state, the output voltage is... With load It doesn't matter; the system can achieve constant voltage output.

[0061] Example 2:

[0062] A switching method for a wireless power transmission system with dual voltage level output, employing the wireless power transmission system with dual voltage level output described in Example 1, includes the following specific steps:

[0063] S1: Collect WPT system circuit parameters and set two wireless charging levels: high voltage and low voltage.

[0064] S2: Obtain the wireless charging voltage required by the receiving unit;

[0065] S3: Match the wireless charging level and control the switching of the control switch and plate capacitor according to the wireless charging voltage required by the receiving unit.

[0066] In this embodiment, when the wireless charging voltage required by the receiving unit is matched to a high voltage level, the control switch... Close, the plate capacitor The two electrode plates are vertically arranged; when the wireless charging voltage required by the receiving unit is matched to a low voltage level, the control switch... Disconnect, the plate capacitor The two plates are set parallel and facing each other.

[0067] In this embodiment, the constant voltage / constant current switching compensation network proposed in this application can only achieve constant voltage / constant current switching under specific compensation conditions. Therefore, in order to achieve this requirement, the relationship between the system parameters is obtained by combining equations (3) and (7):

[0068] (10)

[0069] S4: Simulation Verification:

[0070] To verify the feasibility and effectiveness of the above method, a simulation model was constructed in the COMSOL finite element simulation software as follows. Figure 5 The coupling mechanism shown in the figure has parameter values ​​as shown in Table 1, where: the first transmitting coil Second transmitting coil and receiving coil All are circular planar helical coils, with a winding diameter of d. The second transmitting coil... Set in the first transmitting coil Inside (coplanar and coaxial), second transmitting coil and the first transmitting coil With receiving coil The transmission distance is h.

[0071] Table 1. Parameter Table of Coupling Mechanism

[0072]

[0073] The system parameters obtained from COMSOL simulation and equation (10) are shown in Table 2:

[0074] Table 2 System Parameter Table

[0075]

[0076] To verify the validity of this application, when the system controls the switch... Closed and plate capacitor When the two plates are perpendicular, a simulation was performed in Simulink, and the simulation results are as follows. Figure 6 As shown, by Figure 6It can be seen that when the load increases from 5Ω to 32Ω, the output voltage remains stable at around 110V.

[0077] When the system is controlling the switch Disconnected and capacitor plates When the objects are parallel and aligned, a simulation was performed in Simulink, and the simulation results are as follows. Figure 7 As shown, by Figure 7 It can be seen that the output voltage can remain stable, and when the load increases from 5Ω to 32Ω, the output voltage can remain stable at around 26V.

[0078] In summary, the CLCC-LCC resonant compensation network proposed in this application achieves constant voltage output at two voltage levels through switching. Experimental results show that the system can maintain stable constant voltage output performance at both voltage levels when the load changes from 5Ω to 32Ω.

[0079] 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 implementation 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 scope of protection of the claims of the present invention.

Claims

1. A wireless power transmission system with dual voltage level output, characterized in that, It includes a transmitting unit and a receiving unit, wherein the transmitting unit includes a DC power supply, a high-frequency inverter and a transmitting coil circuit connected in sequence; The transmitting coil circuit is sequentially connected to the first transmitting coil, the first primary resonant capacitor, the control switch, the second primary resonant capacitor, and the second transmitting coil. The other ends of the first transmitting coil and the second transmitting coil are both connected to the output terminal of the high-frequency inverter. A switching circuit is also provided between the first transmitting coil and the second transmitting coil to cooperate with the control switch to enable the system to switch between two voltage levels.

2. The wireless power transmission system with dual voltage level output according to claim 1, characterized in that, The switching circuit includes a primary resonant inductor, a third primary resonant capacitor, and a plate capacitor. One end of the primary resonant inductor and the third primary resonant capacitor are connected to the input and output terminals of the control switch, respectively. The other end of the primary resonant inductor and the third primary resonant capacitor is connected to the other end of the second transmitting coil. The two ends of the plate capacitor are connected to the other end of the first transmitting coil and one end of the primary resonant inductor, respectively. When the two plates of the plate capacitor are parallel and facing each other, the plate capacitor is connected to the system. When the two plates of the plate capacitor are perpendicular, the plate capacitor is disconnected from the system.

3. The wireless power transmission system with dual voltage level output according to claim 1, characterized in that, The first and second transmitting coils are wound in opposite directions.

4. A wireless power transmission system with dual voltage level output according to claim 2, characterized in that, When the control switch is closed, the two plates of the plate capacitor are perpendicular, and the primary resonant inductor, the third primary resonant capacitor, and the plate capacitor are disconnected from the system.

5. A wireless power transmission system with dual voltage level output according to claim 2, characterized in that, When the control switch is off, the two plates of the plate capacitor are parallel and facing each other. The second primary-side resonant capacitor, the third primary-side resonant capacitor, and the second transmitting coil are connected in series to form a relay circuit. The first primary-side resonant capacitor, the plate capacitor, and the primary-side resonant inductor constitute the LCC compensation circuit of the first transmitting coil.

6. A wireless power transmission system with dual voltage level output according to claim 1, characterized in that, The receiving unit includes a receiving coil, a secondary-side compensation circuit, a rectifier, and a load connected in sequence. The secondary-side compensation circuit is an LCC topology.

7. A wireless power transmission system with dual voltage level output according to claim 2, characterized in that, The plate capacitor includes a base plate and a drive motor, as well as a first housing and a second housing rotatably mounted at one end; The first housing and the drive motor are mounted on the base plate. The two plates of the plate capacitor are respectively embedded in the first housing and the second housing. The output shaft of the servo motor is connected to the rotating shaft of the second housing. The servo motor is used to drive the second housing and the embedded plates to rotate.

8. A switching method for a wireless power transfer system with dual voltage level output, characterized in that, The wireless power transmission system with dual voltage level output as described in any one of claims 1-7 comprises the following steps: S1: Collect WPT system circuit parameters and set two wireless charging levels: high voltage and low voltage. S2: Obtain the wireless charging voltage required by the receiving unit; S3: Match the wireless charging level and control the switching of the control switch and plate capacitor according to the wireless charging voltage required by the receiving unit.

9. A switching method for a wireless power transmission system with dual voltage level output according to claim 8, characterized in that, When the wireless charging voltage required by the receiving unit is at a high voltage level, the control switch is closed, and the two plates of the electrode capacitor are arranged vertically; when the wireless charging voltage required by the receiving unit is at a low voltage level, the control switch is open, and the two plates of the electrode capacitor are arranged parallel and facing each other.

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