Wireless charging foreign matter detection system without switch and integrating metal and life body detection functions

Abstract

The invention provides a wireless charging foreign matter detection system which does not have a switch and integrates metal and life body detection functions. Comprising the design of a self-resonance coil and the realization of a switch-free design, in the switch-free design, each detection branch is not provided with a switch, each detection branch is correspondingly configured with an independent resonant frequency point fi, and the equivalent impedance of all non-working branches is ensured to be far greater than the impedance of working branches, so that the non-working branches are in a detuning state; therefore, the detection of the working branch is realized. And the output frequencies of the signal sources are sequentially adjusted to be f1, f2... fn, so that detection of all the detection branches is completed.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless charging foreign object detection, and in particular relates to a wireless charging foreign object detection system without switches and integrating metal and living body detection functions. Background Art

[0002] Electric vehicles currently have problems with mileage and charging. Due to its advantages such as convenience, safety, automation and intelligence, wireless charging technology for electric vehicles has received extensive research and attention from academia and industry. Wireless power transmission technology can be divided into electromagnetic radiation-based wireless power transmission technology based on far fields, and magnetic field coupling or electric field coupling-based wireless power transmission technology based on near fields. Among the wireless charging of electric vehicles, magnetic field coupling wireless power transmission technology is currently the most fully studied, widely used and most mature technology.

[0003] In magnetic field coupling wireless power transmission technology, the magnetic flux generated by the transmitting coil is hinged to the receiving coil, thereby transmitting electrical energy from the transmitting end to the receiving end. There is a strong magnetic field in the charging area formed by the transmitting coil and the receiving coil. The distance from the chassis of the car to the ground is usually more than ten centimeters, or even more than twenty centimeters. The coil size of the electric vehicle wireless charging system is generally not less than 300mm×300mm. Therefore, the charging area of ​​the electric vehicle wireless charging system is relatively large and open. During the charging process, metal foreign objects such as keys, coins or cans can easily fall into the charging area. The strong magnetic field in the charging area will induce eddy currents in these metal foreign objects, causing the metal temperature to rise and causing damage such as fire. At the same time, life forms such as stray cats or dogs will also enter the charging area, especially in winter when they are attracted by the heat generated by the coil, and the strong magnetic field will also cause harm to these life forms.

[0004] Therefore, in the electric vehicle wireless charging system, it is necessary to detect metal foreign objects and living things. Figure 1 shown. Figure 1 The system shown consists of a coil array with a large number of switches and peripheral detection circuits, including voltage followers, high-pass filters, and half-wave rectifiers. C1 , S C2 …S Cn It is a switch used to traverse each detection branch. The traditional wireless charging foreign object detection system can only realize one of the functions of metal object detection or life body detection, and contains a large number of switches. If the foreign object detection system is a metal foreign object detection system, then L C1 , L C2 … L Cn is the inductive detection coil, CC1 , C C2 … C Cn The corresponding resonant capacitor is configured to f 0. If the foreign body detection system is a life detection system, then C C1 , C C2 … C Cn is the capacitive detection coil, L C1 , L C2 … L Cn For the corresponding resonant inductor, the resonant frequency of each detection branch is configured as f 0. At the same time, the system uses fixed frequency detection, and the detection frequency is the resonant frequency f 0.

[0005] The above solutions have the following problems: (1) A large number of switch devices are used, resulting in high cost of the foreign body detection system and occupying a large amount of layout space. (2) Usually, at least two systems are used to perform metal object detection and life body detection respectively, without achieving functional integration. Summary of the invention

[0006] In view of the defects and shortcomings of the above-mentioned prior art, the present invention proposes a wireless charging foreign object detection system without a switch and integrated with metal and living body detection functions, which solves the two problems of the above-mentioned prior art through innovative design.

[0007] The technical solution adopted by the present invention to solve the technical problem is: A switchless wireless charging foreign object detection system: comprising n detection branches; each detection branch is not provided with a switch, and each detection branch is correspondingly configured with a separate resonant frequency point f i , ensuring that the equivalent impedance of all non-working branches is much greater than the impedance of the working branch, so that the non-working branches are in a detuned state, so as to realize the detection of the working branch; by adjusting the output frequency of the signal source in turn, f 1. f 2… f n , to complete the detection of all detection branches.

[0008] Furthermore, the detection branch is provided with a combination of an inductive detection coil and an externally configured resonant capacitor for detecting metal foreign bodies.

[0009] Furthermore, the detection branch is provided with a combination of a capacitive detection coil and an externally configured resonant inductor for life detection.

[0010] Furthermore, a self-resonant coil is provided on the detection branch, and the self-resonant coil includes a unipolar coil on the top layer and a comb-shaped electrode plate on the bottom layer, the top layer and the bottom layer are separated by FR4 medium, and there is no electrical connection between the top layer and the bottom layer.

[0011] Furthermore, the resonance points of the self-resonant coil at different frequencies are achieved by adjusting the number of turns of the coil, the thickness of the FR4 medium, and / or the line width of the coil.

[0012] And, a switchless wireless charging foreign object detection method: each detection branch is not provided with a switch, and each detection branch is correspondingly configured with a separate resonant frequency point f i , ensuring that the equivalent impedance of all non-working branches is much greater than the impedance of the working branch, so that the non-working branches are in a detuned state, so as to realize the detection of the working branch; by adjusting the output frequency of the signal source in turn, f 1. f 2… f n , to complete the detection of all detection branches.

[0013] And, a wireless charging foreign object detection system integrating metal and life body detection functions: comprising n detection branches; each detection branch is provided with a self-resonant coil comprising a unipolar coil on a top layer and a comb-shaped electrode plate on a bottom layer, the top layer and the bottom layer are separated by an FR4 medium, and there is no electrical connection between the top layer and the bottom layer.

[0014] Compared with the prior art, the present invention and its preferred embodiments provide at least the following two outstanding advantages: (1) The proposed system does not need to use a large number of switches to traverse the detection branches, saving costs and circuit board layout space.

[0015] (2) The proposed system can detect metal objects and living organisms at the same time, integrating the metal object detection and living organism detection functions into one system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 It is a traditional wireless charging foreign object detection system; Figure 2 This is a circuit diagram of a switch-free wireless charging foreign object detection system according to Embodiment 1 of the present invention; Figure 3This is a circuit schematic diagram of a wireless charging foreign object detection system with switch and integrated metal and life body detection functions according to Embodiment 2 of the present invention; Figure 4 This is a structural diagram of the self-resonant coil provided in Example 2 of the present invention; Figure 5 : is an equivalent circuit diagram of the self-resonant coil in the second embodiment of the present invention with or without foreign matter; Figure 6 This is a circuit schematic diagram of a switchless wireless charging foreign object detection system with integrated metal and life body detection functions according to Embodiment 3 of the present invention; Figure 7 This is a distribution diagram of the resonant frequencies of each detection branch of the switchless wireless charging foreign object detection system with integrated metal and living body detection functions proposed in Example 3 of the present invention. DETAILED DESCRIPTION

[0017] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows: It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0019] The present invention mainly provides two major innovations: one is the switch-free design, and the other is the integration of metal and life detection. These two innovations can be used separately or together. That is, the present invention can have three schemes. Scheme 1 is a switch-free wireless charging foreign body detection system without integrated metal and life detection functions, scheme 2 is a switch-free wireless charging foreign body detection system with integrated metal and life detection functions, and scheme 3 is a switch-free wireless charging foreign body detection system with integrated metal and life detection functions, which correspond to the following three embodiments respectively: Embodiment 1 is a single switchless design. The proposed switchless wireless charging foreign object detection system without integrated metal and life body detection functions is as follows Figure 2 The proposed switchless method sets a resonant frequency point with sufficient spacing for each detection branch to ensure that the equivalent impedance of all non-working branches is much larger than the impedance of the working branch. For example, when the output frequency of the signal source is f1, the impedance of detection branch 1 is the smallest, and the impedance of the other detection branches is large in the detuned state. The signal mainly flows through detection branch 1, thereby realizing the detection of detection branch 1. By adjusting the output frequency of the signal source in sequence, its output frequency is respectively f 1. f 2… f n , the detection of all detection branches can be completed. If the switchless foreign body detection system is a metal foreign body detection system, then L D1 , L D2 … L Dn is the inductive detection coil, C D1 , C D2 … C Dn The resonant capacitor is configured externally, and the resonant frequency of each detection branch is configured as f 1. f 2… f n If the switchless foreign body detection system is a life detection system, then C D1 , C D2 … C Dn is the capacitive detection coil, L D1 , L D2 … L Dn The resonant inductor is configured externally, and the resonant frequency of each detection branch is configured as f 1. f 2… f n .

[0020] Embodiment 2 is a detection function integrated design, that is, the integration of metal object detection function and life body detection function. The proposed wireless charging foreign body detection system with switch and integrated metal and life body detection functions is as follows: Figure 3 As shown. C1 , S C2 …S Cn It is a switch used to traverse each detection branch. C1 , SR C2 …SR Cn It is a self-resonant coil with inductive and capacitive detection functions and the same size, and the self-resonant frequency is f 0.

[0021] A preferred self-resonant coil structure designed in this embodiment is as follows Figure 4 As shown, it is composed of a unipolar coil on the top layer and a comb-shaped electrode plate on the bottom layer, which are separated by the FR4 medium commonly used in PCB boards and have no direct electrical connection. The equivalent circuit diagram of the self-resonant coil mentioned in this embodiment and its detection principle are shown in Figure 5 As shown. For metal objects, when a metal foreign body approaches the self-detection coil, the inductance of the coil will decrease and the resistance will increase. This principle can be used to detect metal foreign bodies. For living organisms, when a living organism approaches the detection mechanism, mutual capacitance will be formed between the living organism and the detection mechanism, thereby affecting the equivalent capacitance of the detection mechanism. This principle can be used to detect living organisms.

[0022] Embodiment 3 combines the two innovations of switchless design and integration of metal and life body detection functions into one system. Figure 6 As shown. SR D1 , SR D2 …SR Dn It is a self-resonant coil with inductive and capacitive detection functions but different resonant frequencies. The self-resonant frequencies are f 1. f 2… f n The resonance point of the self-resonant coil can be achieved by adjusting the number of turns of the coil, the thickness of the FR4 dielectric, and / or the line width of the coil.

[0023] In summary, since the present invention includes two innovations, one is the switch-free design, and the other is the integration of metal and life body detection, these two innovations can be used separately or together. Figure 6 Taking the proposed switchless wireless charging foreign object detection system with integrated metal and life body detection functions as an example, first determine the length, width and number of self-resonant coils according to the structure and size of the transmitting coil and the receiving coil. Then reasonably use the number of turns of the self-resonant coil and the PCB line width to adjust the resonant frequency points of each self-resonant coil, so that there is enough spacing between each resonant point to ensure that the detection branch in the working state is not interfered by other branches. The distribution is shown in Figure 7 ,| Z | is the module of the impedance and of each branch. Finally, the working frequency of the AC signal source is configured in turn according to the resonant frequency of each self-resonant coil to complete the detection of each detection branch.

[0024] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of wireless charging foreign object detection systems without switches and integrated with metal and life detection functions under the inspiration of this patent. All equal changes and modifications made within the scope of the patent application of the present invention shall be covered by this patent.

Claims

1. A switchless wireless charging foreign object detection system, characterized in that: It includes n detection branches; each detection branch is not provided with a switch, and each detection branch is configured with a separate resonant frequency point f i , ensuring that the equivalent impedance of all non-working branches is much greater than the impedance of the working branches so that the non-working branches are in a detuned state, so as to realize the detection of the working branches; By adjusting the output frequencies of the signal sources respectively f 1. f 2… f n , to complete the detection of all detection branches.

2. The switchless wireless charging foreign object detection system according to claim 1, characterized in that: The detection branch is provided with a combination of an inductive detection coil and an externally configured resonant capacitor for detecting metal foreign bodies.

3. The switchless wireless charging foreign object detection system according to claim 1, characterized in that: The detection branch is provided with a combination of a capacitive detection coil and an externally configured resonant inductor for life body detection.

4. The switchless wireless charging foreign object detection system according to claim 1, characterized in that: The detection branch is provided with a self-resonant coil, which includes a unipolar coil on the top layer and a comb-shaped electrode plate on the bottom layer. The top layer and the bottom layer are separated by FR4 medium, and there is no electrical connection between the top layer and the bottom layer.

5. The switchless wireless charging foreign object detection system according to claim 4, characterized in that: The resonance points of the self-resonant coil at different frequencies are achieved by adjusting the number of turns of the coil, the thickness of the FR4 medium, and / or the line width of the coil.

6. A method for detecting foreign objects in wireless charging without a switch, characterized in that: Each detection branch does not have a switch, and each detection branch is configured with a separate resonant frequency point. f i , ensuring that the equivalent impedance of all non-working branches is much greater than the impedance of the working branches so that the non-working branches are in a detuned state, so as to realize the detection of the working branches; By adjusting the output frequencies of the signal sources respectively f 1. f 2… f n , to complete the detection of all detection branches.

7. A wireless charging foreign object detection system integrating metal and life body detection functions, characterized in that: It comprises n detection branches; each detection branch is provided with a self-resonant coil comprising a unipolar coil at a top layer and a comb-shaped electrode plate at a bottom layer, the top layer and the bottom layer are separated by a FR4 medium, and there is no electrical connection between the top layer and the bottom layer.

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