A Method for Expanding Wireless Charging Function Based on Relay Module

Abstract

The present invention provides a method for expanding the wireless charging function based on a relay module, characterized in that the source module charges the load module through the relay module, and the function of the source module is expanded through the relay module, wherein: the relay module includes an auxiliary relay coil and at least one main relay coil, the relay module can extract sufficient power from the source module, and the extracted power is transmitted to all the main relay coils via a compensation network; the main relay coils are coupled with the coils of the load module to achieve wireless charging of the load module, and different types of main relay coils are selected to meet different charging functions. The present invention adopts different relay coil structures to realize the expansion of various charging functions. The experimental results show that the present invention can ensure the transmission power and efficiency in the full charging area, and takes into account issues such as charging offset tolerance, multi-load, combination of fast and slow charging, user experience, and economic cost.

Description

Technical Field

[0001] The present invention relates to a class of wireless charging transmitters. Background Art

[0002] In recent years, the technology of inductive wireless power transfer (IPT) has developed rapidly, and many technical problems have been effectively solved, which further promotes the wide application of wireless charging technology in the market. At present, most low-power wireless chargers follow the Qi standard, which creates the possibility for the large-scale application of wireless charging. However, the Qi standard also has certain limitations: one is that the charging area is limited. If only a pair of coils with the same size is used as the coupler, the system has a very low tolerance for the offset between the two coils; the other is that most chargers based on the Qi standard cannot support multi-load charging.

[0003] To solve the above problems, some enterprises have given tentative solutions. They can be mainly divided into the following two types: The first is to introduce an electric device in the transmitter. In the charging area, the transmitting coil automatically tracks the position of the receiver and always keeps the center positions of the coupling coils aligned. This solution can ensure the power transmission efficiency at any position, but the introduction of the electric device increases the cost, and the noise generated during operation affects the user experience. The second is to use a multi-coil array to achieve overlapping coverage of the entire charging area and activate the corresponding transmitting coil according to the position of the receiver. This solution can also ensure the power transmission efficiency at any position, but since each transmitting coil is driven by an independent circuit, the cost increases significantly, and the heat dissipation problem during actual operation is difficult to solve. In short, these tentative solutions do not take into account issues such as charging offset tolerance performance, multi-load capacity, user experience, and economic cost, so they have not achieved wide market application. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that most existing medium and low-power wireless charging transmitter products have poor offset tolerance performance and only support single-load charging. In addition, the proposed tentative solutions cannot take into account issues such as charging offset tolerance performance, multi-load capacity, user experience, and economic cost.

[0005] To solve the above technical problem, the technical solution of the present invention is to provide a method for expanding the wireless charging function based on a relay module, which is characterized in that the source module charges the load module through the relay module, and the function of the source module is expanded through the relay module, wherein:

[0006] The relay module includes an auxiliary relay coil and at least one main relay coil. The auxiliary relay coil is coupled with the coil of the source module, enabling the relay module to extract sufficient power from the source module. The extracted power is transmitted to all the main relay coils via a compensation network. A magnetic isolation layer is provided between the auxiliary relay coil and the main relay coils to avoid cross-coupling between the coils. The main relay coils are coupled with the coils of the load module to achieve wireless charging of the load module. Different types of main relay coils are selected to meet different charging functions.

[0007] Preferably, the relay module is designed as a planar structure or a three-dimensional structure with different shapes.

[0008] Preferably, there are at least two main relay coils, including a first main relay coil and at least a second main relay coil. Among them: the first main relay coil is arranged in the single-load fast-charging area and can provide fast charging for a single load module; all the second main relay coils are arranged in the multi-load slow-charging area and can provide slow charging for multiple load modules simultaneously.

[0009] A class of wireless charging function expansion methods based on relay modules proposed by the present invention adopts different relay coil structures to achieve various charging function expansions. Experimental results show that the present invention can ensure the transmission power and efficiency in the full charging area, and takes into account issues such as charging offset tolerance, multi-load, combination of fast and slow charging, user experience, and economic cost. Description of the Drawings

[0010] Figure 1 Schematically shows the basic principle of the wireless charging function expansion method based on relay modules proposed by the present invention, including a source module TX, a relay module ReX, a load module RX, and a compensation network Comp. Figure 1 Shows the entire system architecture and highlights the three-layer structure of the relay module;

[0011] Fig. 2(a) and Fig. 2(b) illustrate a system design form for the combination of fast and slow charging based on relay coils, including the system architecture and the shape of the relay module. Among them: Fig. 2(a) is the system architecture, and the relay module ReX extracts energy from the source module TX and transmits it to a fast-charging module RX1 and multiple slow-charging modules RX2, etc.; Fig. 2(b) designs a bowl-shaped relay module, with the fast-charging module RX1 placed directly above the source module TX and the slow-charging modules RX2 placed around the bowl wall.

[0012] Figure 3 Is the circuit model of the compensation network, including series compensation, T-type compensation, and π-type compensation. Different components can be added to design the compensation networks in the source module TX, the relay module ReX, and the load module RX.

[0013] Figures 4(a) and 4(b) illustrate several topological forms of the relay module ReX, where: Figure 4(a) is the topology of the relay module with a single charging area, L rea is the auxiliary relay coil, L re is the main relay coil, which can charge large-sized loads or multiple loads; Figure 4(b) is the topology of the relay module ReX with two charging areas, L re1 and L re2 respectively represent the two main relay coils of the relay module ReX, L re1 is designed for the single-load fast charging area, L re2 is for the multi-load slow charging area, L r , C r1 , C r2 , C r3 etc. are resonance compensation elements.

[0014] Figure 5 is a circuit topology for realizing the expansion of the wireless charging function using the relay module ReX, including a half-bridge inverter circuit, a source coil and its compensation network, a relay coil and its compensation network, a multi-load coil and its compensation network, and a full-bridge rectifier circuit.

[0015] Figure 6 is the test result of the experimental prototype based on the relay module ReX. When the output powers of RX1 and RX2 are both 5W, the source module current (i tx ), the relay module current (i re ), and the load module current (i rx1 , i rx2 ) can be obtained.

[0016] Figures 7(a) and 7(b) are the voltage gains and power transfer efficiencies of the experimental prototype based on the relay expansion module under different load conditions, where: as can be seen from Figure 7(a), the experimentally obtained voltage gain is basically fitted with the theoretical voltage gain; as shown in Figure 7(b), when the powers of the two load coils vary from 1 to 10W, the overall system has a relatively high efficiency. Specific Embodiments

[0017] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0018] For example Figure 1As shown, the present invention includes a source module TX, a relay module ReX, and a load module RX. The source module TX, the relay module ReX, and the load module RX all have compensation networks for eliminating the reactive power caused by the self-inductance of the coil.

[0019] The relay module ReX has a three-layer structure for expanding the functions of the source module TX. The bottom layer of the relay module ReX is the auxiliary relay coil ReX-a, the top layer is the main relay coil ReX, and a magnetic isolation layer is added between the bottom layer and the top layer to avoid cross-coupling between the auxiliary relay coil ReX-a and the main relay coil ReX.

[0020] When the relay module ReX is placed directly above the source module TX, it can extract sufficient power from the source module TX using the auxiliary relay coil ReX-a to meet the high-offset tolerance or multi-load charging requirements of the load module RX. At the same time, the present invention provides various types of main relay coils ReX to meet different charging functions. Figure 2(a) shows the circuit model of the fast and slow charging combined system, and the position of the main relay coil ReX is shown in Figure 2(b). The overall shape of the relay module ReX is designed as a bowl shape, with two charging areas, namely the bottom charging area and the side charging area. The bottom charging area can provide fast charging for a single device, and the side charging area can provide slow charging for multiple devices.

[0021] The relay module ReX can not only improve the coupling performance of the system but also increase the design freedom of the system. Compensation network topologies such as SS, LCC-S, and LCC-LCC can be used to design the source module TX, the relay module ReX, and the load module RX, and the basic compensation network is as Figure 3 shown. At the same time, as shown in Figures 4(a) and 4(b), the present invention provides several topological forms of the relay module ReX, including topologies with single charging areas and double charging areas.

[0022] The relay module ReX can be customized for different applications. It is not limited to a planar structure and can be designed into various shapes to overcome the limitations of the original source module TX. From the perspective of the manufacturer, the original source module TX can still be used as a basic function charger to supply power to the load device, and the relay module ReX can be used as an optional auxiliary module to provide unique charging functions. It should be emphasized here that the coil structure and topological forms on the transmitter side based on relay coils provided by the present invention are only for illustrative purposes and do not limit their scope. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0023] Take Figure 5The circuit topology described above further illustrates the present invention. The circuit topology includes a half-bridge inverter circuit, a source coil and its compensation network, and a relay coil and its compensation network, which are represented by a circuit model. Here, the receiver can take various forms, and only as an example, it includes a load coil and its compensation network, a rectifier circuit, which are also represented by a circuit model.

[0024] In Figure 5 the circuit topology shown, the power supply (v in ) is output through the half-bridge inverter circuit and connected to the source coil compensation network (capacitor C tx ) and the source coil (equivalent inductor L tx ), the relay coil (equivalent inductor L re + L rea ) and its compensation network (capacitor C r ), to the multi-load coils (equivalent inductors L rx1 and L rx2 ) and their compensation networks (capacitors C rx1 and C rx2 ), and supplies power to the loads (R o1 and v o1 ) through the outputs (v L1 and R L2 ).

[0025] Figure 5 Among them, the sizes of L tx and L rea are the same, and the coupling between the two coils is strong, so that the relay module can extract sufficient power from the source module. L re is a relay coil with a larger volume compared to L rea , which can provide sufficient charging area for multiple loads. Considering electromagnetic safety, the maximum power of each load is set to 10W.

[0026] Figure 5 The main parameters of each stage of the circuit shown satisfy the following conditions:

[0027]

[0028] In the formula, ω represents the system operating angular frequency.

[0029] The voltage gain of the system is as follows:

[0030]

[0031] In the formula, M rer1 represents the mutual inductance between the relay coil L re1 and the load coil L rx1 , M trea represents the mutual inductance between the source coil TX and the relay coil L rea , and M rer2Indicates the relay coil L re2 and the load coil L rx2 's mutual inductance.

[0032] According to the above-mentioned solution, for Figure 1 a class of wireless charging function expansion solutions based on relay modules shown, an experimental prototype was made, and its parameters are shown in Table 1 below:

[0033] <![CDATA[Operating frequency f s > 125 kHz <![CDATA[DC input voltage V d > 20V <![CDATA[Self-inductance L of the source coil tx > 17.9 μH <![CDATA[Self-inductance L of the load coil rx1 > 19.3 μH <![CDATA[Self-inductance L of the load coil rx2 > 28.4 μH <![CDATA[Self-inductance L of the relay coil rea > 23.5 μH <![CDATA[Self-inductance L of the relay coil re > 44.8 μH <![CDATA[Source coil compensation capacitor C tx > 90.6 nF <![CDATA[Load coil compensation capacitor C rx1 > 83.9 nF <![CDATA[Load coil compensation capacitor C rx2 > 57.1 nF <![CDATA[Relay coil compensation capacitor C r > 23.8 nF <![CDATA[Full load output power P L1 +P L2 > 20W

[0034] Table 1 Parameters of the prototype of the wireless charging function expansion solution based on relay modules

[0035] The test results of the experimental prototype based on the above parameters are shown respectively in Figure 6 , Figure 7(a) and Figure 7(b). It can be seen that the input voltage v in after the half-bridge inverter is a soft switch, which can effectively reduce power consumption and improve the electromagnetic interference problem. When the input voltage v in remains constant, the current of the relay module ReX remains basically constant, and it can establish a stable coupling magnetic field to transfer power to the load end. i tx , i re and i rx1 (or i rx2 ) have a 90° phase difference, which is consistent with the theoretical analysis. The voltage gain of the system under different loads was measured, and the experimental results basically match the theoretical analysis results. The error mainly comes from the power consumption of the inverter, rectifier and coil parasitic resistance. It is calculated that the system has a high efficiency at different powers for the load modules RX1 and RX2.

[0036] Thus, it can be seen that a class of wireless charging function expansion methods based on relay modules proposed by the present invention can effectively overcome the deficiencies existing in the existing product solutions, ensure the overall power transmission efficiency of the system. At the same time, the solution is simple and clear, taking into account issues such as charging offset tolerance performance, multiple loads, combination of fast and slow charging, user experience, and economic cost.

Claims

1. A method for expanding the wireless charging function based on a relay module, characterized in that, The source module (TX) charges the load module (RX) through the relay module (ReX) and expands the functions of the source module (TX) through the relay module (ReX), where: The relay module (ReX) includes an auxiliary relay coil (ReX-a) and at least two main relay coils (ReX). The auxiliary relay coil (ReX-a) is inductively coupled to the coil of the source module (TX) so that the relay module (ReX) can extract sufficient power from the source module (TX). The extracted power is transferred to all the main relay coils (ReX) via a compensation network. A magnetic isolation layer is provided between the auxiliary relay coil (ReX-a) and the main relay coils (ReX) to avoid cross-coupling between the coils. The main relay coils (ReX) are inductively coupled to the coil of the load module (RX) to achieve wireless charging of the load module (RX). Different types of main relay coils (ReX) are selected to meet different charging functions. At least two of the main relay coils (ReX) include a first main relay coil (ReX1) and at least one second main relay coil (ReX2), where: The first main relay coil (ReX1) is arranged in a single-load fast-charging area and can provide fast charging for a single load module (RX). All the second main relay coils (ReX2) are arranged in a multi-load slow-charging area and can provide slow charging for multiple load modules (RX) simultaneously.

2. The method for expanding the wireless charging function based on a relay module according to claim 1, wherein, The relay module (ReX) is designed as a planar structure or a three-dimensional structure of different shapes.

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