Wide-distance adaptive wireless charging system based on hybrid topology

Abstract

The invention provides a wide-distance self-adaptive cross decoupling type wireless charging system based on hybrid topology, and aims to solve the problems that distance self-adaptive wireless power transmission is realized by adding an additional control circuit or introducing a switching device in the existing method, so that the size of the whole structure is greatly increased; and the switching of the system state also leads to the instability of the system. The system comprises an LCC-S topological structure and an S-LCC topological structure, the LCC-S topological structure and the S-LCC topological structure form an input-series output-parallel type LCC / S-S / LCC hybrid compensation topological structure; the first transmitting coil and the first receiving coil in the LCC-S topological structure and the second transmitting coil and the second receiving coil in the S-LCC topological structure form a magnetic coupling structure. The invention belongs to the technical field of magnetic coupling resonant wireless power transmission.

Description

Technical Field

[0001] The invention relates to a wide-distance adaptive wireless charging system, belonging to the technical field of magnetic coupling resonance type wireless power transmission. Background Art

[0002] Due to the limitations of low power density, high cost, and heavy weight, the development and application of battery-powered devices are facing unprecedented technical challenges. As a new power supply method, wireless power transmission provides a new way to obtain energy for power-driven devices, thereby alleviating excessive dependence on batteries. Compared with other wireless power transmission technologies, magnetically coupled resonant wireless power transmission technology has the advantages of long transmission distance, high power level, and high efficiency.

[0003] Research on distance-adaptive magnetically coupled resonant wireless charging systems has been carried out. Through reasonable design of the magnetic coupling mechanism and compensation topology, the entire wireless charging structure can still achieve stable power output and high efficiency when the transmission distance varies over a large range, without adding additional control circuits, thereby simplifying the complexity of the design and reducing costs.

[0004] At present, some people have proposed a variety of wireless charging systems for variable distances. For example, by adding additional impedance matching circuits, impedance matching is performed at different transmission distances, so that the system always maintains a completely resonant state to achieve efficient output. Others have introduced switching devices in the resonant cavity. At different transmission distances, the resonant cavity of the access circuit is changed by switching the switching devices to achieve efficient transmission of electric energy. The above methods all achieve distance-adaptive wireless power transmission by adding additional control circuits or introducing switching devices, which greatly increases the volume of the entire structure, and the switching of the system state will also cause system instability. Summary of the invention

[0005] The present invention aims to solve the problem that existing methods all achieve distance-adaptive wireless power transmission by adding additional control circuits or introducing switching devices, which greatly increases the volume of the entire structure, and the switching of system states also causes system instability. A wide-distance adaptive wireless charging system based on a hybrid topology is proposed.

[0006] The technical solution adopted by the present invention to solve the above problems is: the present invention includes an LCC-S topology structure and an S-LCC topology structure;

[0007] The LCC-S topology and the S-LCC topology form an input series output parallel type LCC / SS / LCC hybrid compensation topology;

[0008] The first transmitting coil and the first receiving coil in the LCC-S topology structure and the second transmitting coil and the second receiving coil in the S-LCC topology structure form a magnetic coupling structure.

[0009] Further, the center distance between the first transmitting coil and the second transmitting coil is r;

[0010] The center distance between the first receiving coil and the second receiving coil is r;

[0011] The outer diameters of the first transmitting coil, the first receiving coil, the second transmitting coil and the second receiving coil are all 2r;

[0012] The width of the first transmitting coil, the first receiving coil, the second transmitting coil and the second receiving coil are all 0.4r.

[0013] Furthermore, the r value is 111 mm.

[0014] Furthermore, the inductor L1 in the LCC-S topology is 2.5 μH, and the inductor L2 in the S-LCC topology is 12.1 μH.

[0015] The beneficial effects of the present invention are:

[0016] 1. The present invention eliminates the introduction of complex control circuits and directly adopts a hybrid compensation topology. Relying on its own transmission characteristics, it can achieve stable constant power transmission under variable distance conditions, thus reducing the complexity of system design;

[0017] 2. The present invention adopts a cross-decoupling design of the coil, which realizes coil decoupling without introducing additional circuit devices, and can match the compensation topology of the present invention in the simplest way. There is no need to perform switch switching when the transmission distance changes, which greatly improves the working stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the circuit compensation topology;

[0019] Figure 2 is a schematic diagram of the magnetic coupling structure;

[0020] Figure 3 It is a schematic diagram of the maximum gain fluctuation with mutual inductance;

[0021] Figure 4 It is a schematic diagram of the fluctuation of each structure gain with mutual inductance;

[0022] Figure 5 It is a schematic diagram of gain fluctuation. DETAILED DESCRIPTION

[0023] Specific implementation method 1: Figure 1 and Figure 2As shown, a wide-distance adaptive wireless charging system based on a hybrid topology includes an LCC-S topology structure 1 and an S-LCC topology structure 2;

[0024] The LCC-S topology 1 and the S-LCC topology 2 form an input series output parallel type LCC / SS / LCC hybrid compensation topology;

[0025] The first transmitting coil L in the LCC-S topology 1 P1 and the first receiving coil L S1 The second transmitting coil L in the S-LCC topology 2 P2 and the second receiving coil L S2 Form a magnetic coupling structure.

[0026] Among them, the first transmitting coil L P1 With the second transmitting coil L P2 The center distance is r;

[0027] The first receiving coil L S1 and the second receiving coil L S2 The center distance is r;

[0028] The first transmitting coil L P1 , the first receiving coil L S1 , the second transmitting coil L P2 and the second receiving coil L S2 The outer diameter of is 2r;

[0029] The first transmitting coil L P1 , the first receiving coil L S1 , the second transmitting coil L P2 and the second receiving coil L S2 The width is 0.4r.

[0030] The r value is 111 mm.

[0031] The inductor L1 in the LCC-S topology structure 1 is 2.5 μH, and the inductor L2 in the S-LCC topology structure 2 is 12.1 μH.

[0032] How it works

[0033] In a wireless power transmission system with a changing transmission distance, the coupling coefficient of the magnetic coupling mechanism will change in the opposite trend of the transmission distance. The fluctuation of the coupling coefficient will cause instability in the output of the entire system. Therefore, the analysis of the compensation topology under variable distance conditions is mainly based on stabilizing the system output. The output characteristics and gain values ​​of six common voltage source driven compensation topologies under full reactive compensation of the system at full resonance are derived as shown in Table 1.

[0034] Table 1 Basic transfer characteristics of common compensation topologies

[0035]

[0036]

[0037] Assume that the fluctuation range of the mutual inductance between the primary and secondary sides of the magnetic coupling mechanism changes with the transmission distance M∈(M a , M b ), with mutual inductance M0∈(M a , M b ) is used as the reference to normalize the gain, and we can get a and M=M b The normalized gains of the SS compensation topology at time are:

[0038]

[0039] It can be seen that no matter whether it is the compensation topology of constant current output or the compensation topology of constant voltage output, their gain is always proportional or inversely proportional to the fluctuation of mutual inductance. In other words, when the system is completely resonant, when the transmission distance changes, a single compensation topology cannot neutralize the negative impact of the change in transmission distance on the system.

[0040] The previous analysis shows that a single compensation topology alone cannot achieve constant power and high-efficiency output of a wireless power transmission system under variable distance conditions. The gain of each compensation topology varies in direct or inverse proportion to the mutual inductance. If two compensation topologies whose gain varies in opposite trends with mutual inductance are mixed, a set of compensation topologies whose output is insensitive to changes in transmission distance can be achieved.

[0041] Assuming that the compensation topology has only two connection modes, series and parallel, there are four connection modes for the hybrid compensation topology, namely input parallel output parallel (IPOP), input parallel output series (IPOS), input series output parallel (ISOP), and input series output series (ISOS). Through simple circuit relationship deduction, the relationship between the transconductance and gain of the four circuit connection modes in constant current and constant voltage output modes and the gain of a single compensation topology can be obtained, as shown in Table 2.

[0042] Table 2 Output characteristics of hybrid compensation topology

[0043]

[0044]

[0045] In order to prevent the danger of overcurrent and overvoltage caused by excessive gain or transconductance, it is also necessary to give priority to compensation topologies with adjustable parameters. The S / S and LCC / LCC compensation topologies are initially selected to achieve constant current output in the form of ISOS connection, and LCC / S and S / LCC are initially selected to achieve constant voltage output in the form of ISOP connection.

[0046] The structural diagrams of ISOS type S / S-LCC / LCC hybrid compensation topology and ISOP type LCC / SS / LCC hybrid compensation topology are shown in Figure 1 shown.

[0047] According to the above formula, the transconductance and gain of the hybrid compensation topology can be derived as follows:

[0048]

[0049] Analyze the fluctuation of transconductance and gain relative to the mutual inductance of the primary and secondary sides of the magnetic coupling mechanism, and obtain the partial derivative of the mutual inductance:

[0050]

[0051] In order to more intuitively compare the fluctuation of the gain of the two hybrid compensation topologies with the mutual inductance, they are plotted as curves, such as Figure 2 As shown in the figure, it can be clearly seen that the voltage gain of the ISOP type LCC / SS / LCC hybrid compensation topology fluctuates less with the mutual inductance, which means that the ISOP type LCC / SS / LCC hybrid compensation topology is more suitable for wireless power transmission under variable distance conditions.

[0052] The above analysis is based on ideal conditions, that is, the primary coil of the magnetic coupling mechanism is not coupled, and the secondary coil is also the same. Therefore, the actual system needs to decouple the magnetic coupling mechanism. In order not to add additional circuit components, this design adopts cross-decoupling. The magnetic coupling mechanism with different coil inner diameters and turns is simulated and analyzed by MAXWELL simulation software, and the size of the magnetic coupling mechanism is finally determined. Then, the coupling between the primary coil and the secondary coil at different center distances is simulated and observed. The final magnetic coupling mechanism is as follows Figure 3 shown.

[0053] Combine the parameters of each part of the magnetic coupling mechanism to design the parameters of the compensation topology. Let L2 = aL1, where a is a constant greater than zero. From the previous analysis, we can see that when The ISOP type LCC / SS / LCC hybrid compensation topology achieves the maximum voltage gain The relationship between voltage gain E and mutual inductance M can be rewritten as:

[0054]

[0055] For different values ​​of maximum gain and resonant inductor L1, the gain fluctuation of ISOP type LCC / SS / LCC hybrid compensation topology with transmission distance is analyzed. The fluctuation of voltage gain with transmission distance is analyzed for three cases where the maximum voltage gain is 1, 1.1, and 1.2, and the optimal value of inductor L1 is determined in these three cases. Then, these three optimal cases are compared. The results are shown as follows: Figure 4 shown.

[0056] Therefore, when the transmission distance varies between d0-10d0, the difference in the voltage gain between the two terminals under the three maximum gain conditions is very small. Considering that the input-output voltage ratio of the system is preferably one-to-one, most voltage gains should be kept close to 1. Therefore, the following situation is relatively optimal.

[0057]

[0058] The parameters of each part of the system are finally obtained as shown in Table 3. Finally, the output gain fluctuations of the single-coil single-compensation topology, the multi-coil non-decoupled compensation topology and the multi-coil decoupled compensation topology with the same parameter configuration as the transmission distance are plotted on Figure 5 middle.

[0059] Table 3 System parameters

[0060]

[0061] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A wide-distance adaptive wireless charging system based on hybrid topology, characterized in that: Including LCC-S topology (1) and S-LCC topology (2); The LCC-S topology (1) and the S-LCC topology (2) form an input series output parallel type LCC / SS / LCC hybrid compensation topology; The first transmitting coil (L P1 ) and the first receiving coil (L S1 ) and the second transmitting coil (L P2 ) and the second receiving coil (L S2 ) form a magnetic coupling structure.

2. The wide-distance adaptive wireless charging system based on hybrid topology according to claim 1, characterized in that: The first transmitting coil (L P1 ) and the second transmitting coil (L P2 )’s center distance is r; The first receiving coil (L S1 ) and the second receiving coil (L S2 )’s center distance is r; The first transmitting coil (L P1 )、The first receiving coil (L S1 ), the second transmitting coil (L P2 ) and the second receiving coil (L S2 ) has an outer diameter of 2r; The first transmitting coil (L P1 )、The first receiving coil (L S1 ), the second transmitting coil (L P2 ) and the second receiving coil (L S2 ) has a width of 0.4r.

3. The wide-distance adaptive wireless charging system based on hybrid topology according to claim 2, characterized in that: The r value is 111 mm.

4. The wide-distance adaptive wireless charging system based on hybrid topology according to claim 1, characterized in that: The inductor L1 in the LCC-S topology (1) is 2.5 μH, and the inductor L2 in the S-LCC topology (2) is 12.1 μH.

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