Overvoltage protection circuit, wireless charging receiving end circuit and wireless charging system

Abstract

The invention provides an overvoltage protection circuit, a wireless charging receiving end circuit and a wireless charging system, and relates to the technical field of wireless charging. The overvoltage protection circuit comprises an overvoltage detection circuit and a protection capacitor. The first end of the protection capacitor is used for being connected with the first end of the receiving end compensation capacitor, and the second end of the protection capacitor is connected with the first connecting end of the overvoltage detection circuit; the second connecting end of the overvoltage detection circuit is used for being connected with the second end of the receiving end compensation capacitor, the detection end of the overvoltage detection circuit is used for being connected with the positive output end of the wireless charging receiving end circuit, and the reference end of the overvoltage detection circuit is used for inputting protection voltage; the overvoltage detection circuit is used for detecting the voltage of the positive output end of the wireless charging receiving end circuit, and when it is determined that the voltage is larger than or equal to the protection voltage, the second end of the protection capacitor and the second end of the receiving end compensation capacitor are connected so as to switch in the protection capacitor. According to the scheme, overvoltage protection of the receiving end of the wireless charging system can be realized, and temperature rise is reduced.

Description

Technical Field

[0001] This application relates to the field of wireless charging technology, and in particular to an overvoltage protection circuit, a wireless charging receiver circuit, and a wireless charging system. Background Technology

[0002] Wireless charging technology (also known as inductive charging or wireless energy transfer technology) is a technology that uses electromagnetic induction to transfer energy from the transmitter to the receiver. It has flexible charging methods and superior protection performance, and has been widely used in various electronic devices. Electronic devices can be charged without the need for a charging cable to connect to the charging platform.

[0003] Figure 1 A schematic diagram of the structure of a wireless charging system in the related art is shown, with reference to... Figure 1 As shown, the DC voltage provided by the DC power supply Vin is converted into AC voltage by the inverter bridge, which drives the resonant circuit composed of the transmitter compensation capacitor C1 and the transmitter coil L1 to generate a high-frequency magnetic field. According to the law of electromagnetic induction, the receiver coil L2 can induce a high-frequency AC voltage. This high-frequency AC voltage passes through the receiver compensation capacitor C2 and enters the synchronous rectification circuit for rectification before being output to the load RL. Since the energy transmitter and receiver of the wireless charging system are isolated from each other, when the load RL changes abruptly or the coupling changes, causing faults such as overvoltage, undervoltage, or charging interruption at the receiver, the transmitter needs to adjust the energy transmission in a timely manner. When the load RL at the receiver suddenly decreases or the receiver suddenly returns from the offset position to the upright position, the energy emitted by the transmitter will be much greater than the energy required by the receiver. Moreover, the communication between the receiver and the transmitter requires signal sampling by the receiver controller, encoding and modulation by the modulation circuit, signal demodulation by the demodulation circuit, and decoding by the transmitter controller. There will be a communication delay between the transmitter and the receiver, making it difficult for the transmitter to respond quickly to the overvoltage signal of the receiver, which can easily cause overvoltage at the receiver and damage the circuit.

[0004] Therefore, overvoltage protection for the receiver circuit of a wireless charging system is particularly important. Summary of the Invention

[0005] This application provides an overvoltage protection circuit, a wireless charging receiver circuit, and a wireless charging system to solve the overvoltage problem at the receiver of the wireless charging system and achieve overvoltage protection at the receiver of the wireless charging system.

[0006] In a first aspect, this application provides an overvoltage protection circuit applied to a wireless charging receiver circuit. The wireless charging receiver circuit includes a receiver coil, a receiver compensation capacitor, and a synchronous rectification circuit. The first end of the receiver compensation capacitor is connected to the second input end of the synchronous rectification circuit through the receiver coil. The second end of the receiver compensation capacitor is connected to the first input end of the synchronous rectification circuit. The output end of the synchronous rectification circuit serves as the output end of the wireless charging receiver circuit and is connected to the load. The overvoltage protection circuit includes an overvoltage detection circuit and a protection capacitor. The first end of the protection capacitor serves as the first connection terminal of the overvoltage protection circuit and is connected to the first end of the receiving end compensation capacitor; the second end of the protection capacitor is connected to the first connection terminal of the overvoltage detection circuit. The second connection terminal of the overvoltage detection circuit serves as the second connection terminal of the overvoltage protection circuit and is connected to the second terminal of the compensation capacitor at the receiving end. The detection terminal of the overvoltage detection circuit is connected to the positive output terminal of the wireless charging receiving end circuit, and the reference terminal of the overvoltage detection circuit is used to input the protection voltage. The overvoltage detection circuit is used to detect the voltage at the positive output terminal of the wireless charging receiver circuit. When it is determined that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than or equal to the protection voltage, the second terminal of the protection capacitor is connected to the second terminal of the receiver compensation capacitor to switch the protection capacitor.

[0007] In one alternative design, the overvoltage detection circuit includes a comparator and a switching circuit; The first input terminal of the comparator serves as the detection terminal of the overvoltage detection circuit and is connected to the positive output terminal of the wireless charging receiver circuit. The second input terminal of the comparator serves as the reference terminal of the overvoltage detection circuit and is used to input the protection voltage. The output terminal of the comparator is connected to the controlled terminal of the switching circuit. The first terminal of the switching circuit is connected to the second terminal of the protection capacitor as the first connection terminal of the overvoltage detection circuit, and the second terminal of the switching circuit is connected to the second terminal of the receiving compensation capacitor as the second connection terminal of the overvoltage detection circuit. The comparator is used to detect the voltage at the positive output terminal of the wireless charging receiver circuit. When it is determined that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, the comparator controls the switching circuit to turn on. When the switching circuit is turned on, it connects the second terminal of the protection capacitor with the second terminal of the receiver compensation capacitor.

[0008] In one alternative design, the switching circuit includes an N-type MOS transistor, the first input terminal of the comparator is a positive input terminal, and the second input terminal of the comparator is a negative input terminal; The drain of the N-type MOS transistor is connected to the second terminal of the protection capacitor as the first terminal of the switching circuit. The source of the N-type MOS transistor is connected to the second terminal of the receiving compensation capacitor in the wireless charging receiver circuit as the second terminal of the switching circuit. The gate of the N-type MOS transistor is connected to the output terminal of the comparator as the controlled terminal of the switching circuit. When the comparator determines that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, it outputs a positive voltage drive signal to the gate of the N-type MOS transistor to control the N-type MOS transistor to turn on.

[0009] In one alternative design, the switching circuit includes a P-type MOS transistor, the first input terminal of the comparator is a negative input terminal, and the second input terminal of the comparator is a positive input terminal; The drain of the P-type MOS transistor is connected to the second terminal of the protection capacitor as the first terminal of the switching circuit. The source of the P-type MOS transistor is connected to the second terminal of the receiving compensation capacitor in the wireless charging receiver circuit as the second terminal of the switching circuit. The gate of the P-type MOS transistor is connected to the output terminal of the comparator as the controlled terminal of the switching circuit. When the comparator determines that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, it outputs a negative voltage drive signal to the gate of the P-type MOS transistor to control the P-type MOS transistor to turn on.

[0010] In one optional design, when the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, the voltage input to the reference terminal of the overvoltage detection circuit switches from the protection voltage to a safety threshold voltage; the safety threshold voltage is the difference between the protection voltage and a preset safety hysteresis voltage. The overvoltage detection circuit is further configured to disconnect the second terminal of the protection capacitor from the second terminal of the receiver compensation capacitor when it is determined that the voltage at the positive output terminal of the wireless charging receiver circuit is less than the safety threshold voltage, thereby disconnecting the protection capacitor.

[0011] In one alternative design, the protection capacitor is at least one capacitor connected in parallel.

[0012] In a second aspect, this application provides a wireless charging receiver circuit, including a receiver coil, a receiver compensation capacitor, a synchronous rectification circuit, and an overvoltage protection circuit as described in any of the first aspects, wherein the overvoltage protection circuit includes an overvoltage detection circuit and a protection capacitor. The first end of the receiving end compensation capacitor is connected to the second input end of the synchronous rectification circuit through the receiving end coil. The second end of the receiving end compensation capacitor is connected to the first input end of the synchronous rectification circuit. The output end of the synchronous rectification circuit serves as the output end of the wireless charging receiving end circuit. The first end of the protection capacitor is connected to the first end of the receiving end compensation capacitor, and the second end of the protection capacitor is connected to the first connection end of the overvoltage detection circuit; the second connection end of the overvoltage detection circuit is connected to the second end of the receiving end compensation capacitor, the detection end of the overvoltage detection circuit is connected to the positive output end of the synchronous rectification circuit, and the reference end of the overvoltage detection circuit is used to input the protection voltage.

[0013] In an optional design, the wireless charging receiver circuit further includes a controllable voltage source and a receiver controller; The output terminal of the controllable voltage source is connected to the reference terminal of the overvoltage detection circuit, and the controlled terminal of the controllable voltage source is connected to the first control terminal of the receiver controller. The receiver controller is used to switch the voltage output from the controllable voltage source from the protection voltage to a safety threshold voltage when it detects that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage; the safety threshold voltage is the difference between the protection voltage and a preset safety hysteresis voltage.

[0014] Thirdly, this application provides a wireless charging system, including a wireless charging transmitter circuit and a wireless charging receiver circuit as described in any of the second aspects; the wireless charging transmitter circuit and the wireless charging receiver circuit are coupled through the transmitter coil of the wireless charging transmitter circuit and the receiver coil of the wireless charging receiver circuit.

[0015] Fourthly, this application provides a chip that includes an overvoltage protection circuit as described in any of the first aspects, or a wireless charging receiver circuit as described in any of the second aspects.

[0016] Fifthly, this application provides an electronic device including an overvoltage protection circuit as described in any of the first aspects above, or a wireless charging receiver circuit as described in any of the second aspects, or a chip as described in the fourth aspect.

[0017] The overvoltage protection circuit, wireless charging receiver circuit, and wireless charging system provided in this application include an overvoltage protection circuit comprising an overvoltage detection circuit and a protection capacitor. The first terminal of the protection capacitor serves as the first connection terminal of the overvoltage protection circuit, connected to the first terminal of the receiver compensation capacitor in the wireless charging receiver circuit. The second terminal of the protection capacitor is connected to the first connection terminal of the overvoltage detection circuit. The second connection terminal of the overvoltage detection circuit serves as the second connection terminal of the overvoltage protection circuit, connected to the second terminal of the receiver compensation capacitor in the wireless charging receiver circuit. The detection terminal of the overvoltage detection circuit is connected to the positive output terminal of the wireless charging receiver circuit, and the reference terminal of the overvoltage detection circuit is used to input the protection voltage. Specifically, the overvoltage detection circuit detects the voltage at the positive output terminal of the wireless charging receiver circuit. When it determines that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than or equal to the protection voltage, it connects the second terminal of the protection capacitor to the second terminal of the receiver compensation capacitor to activate the protection capacitor. At this time, the protection capacitor is connected in parallel with the compensation capacitor at the receiving end, which increases the compensation capacitor value at the receiving end. This can immediately change the resonance state of the entire wireless charging system, reduce the intrinsic resonant frequency, and thus reduce the voltage transmission gain from the transmitter to the receiver. This quickly reduces the voltage output from the wireless charging receiver circuit to the load, enabling overvoltage protection of the wireless charging system receiver circuit before overvoltage communication occurs between the receiver and the transmitter. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a wireless charging system in related technologies; Figure 2 This is a schematic diagram illustrating the overvoltage protection scheme of a wireless charging system in related technologies. Figure 3 This is one of the structural schematic diagrams of the overvoltage protection circuit provided in the embodiments of this application; Figure 4 This is a second schematic diagram of the overvoltage protection circuit provided in the embodiments of this application; Figure 5 This is the third schematic diagram of the overvoltage protection circuit provided in the embodiments of this application; Figure 6 This is one of the structural schematic diagrams of the wireless charging receiver circuit provided in the embodiments of this application; Figure 7 A second schematic diagram of the wireless charging receiver circuit provided in the embodiments of this application; Figure 8 This is one of the structural schematic diagrams of the wireless charging system provided in the embodiments of this application; Figure 9 This is a second schematic diagram of the structure of the wireless charging system provided in the embodiments of this application. Detailed Implementation

[0019] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c. a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0021] The terms "connected" and "connected" should be interpreted broadly. For example, in circuit structures, "connected" or "connected" can refer not only to physical connections but also to electrical or signal connections. This could be a direct connection (physical connection) or an indirect connection via at least one intermediate component, as long as the circuit is connected. It could also refer to the internal connection between two components. Similarly, a signal connection can refer to a connection via a circuit or a medium, such as radio waves. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0022] Reference Figure 1As shown, in a wireless charging system, the transmitter and receiver can be coupled through the transmitter coil L1 and the receiver coil L2, where k represents the coupling coefficient. Since the energy transmitter and receiver are isolated from each other in a wireless charging system, when sudden changes in load RL or coupling cause overvoltage, undervoltage, or charging interruption at the receiver, the transmitter needs to adjust energy transmission promptly. However, communication between the transmitter and receiver involves signal sampling by the receiver controller, encoding and modulation by the modulation circuit, demodulation by the demodulation circuit, and decoding by the transmitter controller, resulting in a communication delay of at least tens of milliseconds. If the receiver does not take protective measures during this time, it will severely damage its components. When the load RL at the receiver suddenly decreases or the receiver suddenly returns from an offset position to a facing position, the energy emitted by the transmitter will be much greater than the energy required by the receiver, easily causing overvoltage at the receiver. Moreover, due to the communication delay between the transmitter and receiver, the transmitter cannot respond quickly to the overvoltage signal from the receiver, easily causing overvoltage at the receiver and damaging the circuit. Therefore, overvoltage protection for the receiver circuit of a wireless charging system is particularly important.

[0023] In related technologies, overvoltage protection can be provided for the receiver circuit of a wireless charging system by using a bleed resistor protection or a current source load protection scheme.

[0024] Figure 2 A schematic diagram of the overvoltage protection scheme for a wireless charging system in related technologies is shown. (Refer to...) Figure 2 As shown, at the receiving end, comparator A01 can be used to compare the voltage output from the synchronous rectifier circuit's output terminal VRECT with the protection voltage VOVP. When the voltage output from VRECT is greater than VOVP, switch S5 is turned on to connect the bleeder resistor R1. At this time, the energy at the receiving end is discharged through the bleeder resistor R1, causing the voltage output from VRECT to decrease, thus achieving overvoltage protection at the receiving end. Alternatively, at the receiving end, comparator A02 can be used to compare the voltage output from VRECT with VOVP. When the voltage output from VRECT is greater than VOVP, switch S6 is turned on to connect the current source load I. At this time, the energy at the receiving end is discharged through the current source load I, causing the voltage output from VRECT to decrease, thus achieving overvoltage protection at the receiving end.

[0025] Figure 2Using a bleed resistor R1 or a current source load I as the energy discharge channel can discharge excess energy to some extent. However, when the load RL suddenly changes from heavy to light load, or when the entire wireless charging system suddenly changes from weak to strong coupling, both energy discharge schemes will cause the energy transmitted by the transmitter to exceed the energy required by the receiver. In this case, the receiver will still experience severe overvoltage. The protection circuit often needs to handle a significant amount of excess energy to reduce the voltage at the output of the synchronous rectifier circuit, such as 2W to 4W of excess energy, where W represents the unit of energy, "watts". However, since the receiver cannot actively adjust or disconnect energy transmission, and the number of bleed resistors R1 and current source loads I is limited, the protection circuit at the receiver has limited discharge capacity during the communication delay when the overvoltage is severe, and the receiver will remain in an overvoltage state. Moreover, the discharge protection circuit also bears a large amount of power, which consumes excess energy. The discharge protection circuit itself will heat up rapidly, causing the receiver to overheat and potentially damaging the receiver circuit. It is also very easy to cause continuous overvoltage damage to the receiver and thermal damage to the discharge protection circuit during the communication delay phase.

[0026] Based on this, this application provides an overvoltage protection circuit for a wireless charging receiver circuit. By detecting the voltage at the positive output terminal of the wireless charging receiver circuit, and determining that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, an additional protection capacitor is connected to both ends of the receiver compensation capacitor. This can change the resonance state of the entire wireless charging system, reduce the voltage gain from the transmitter to the receiver, and thus quickly reduce the output voltage of the wireless charging receiver circuit, achieving the purpose of overvoltage protection at the receiver.

[0027] The following is combined Figures 3-5 The overvoltage protection circuit provided in this application embodiment is described in detail. This overvoltage protection circuit can be applied to the wireless charging receiver circuit in a wireless charging system. The wireless charging receiver circuit includes a receiver coil, a receiver compensation capacitor, and a synchronous rectification circuit. The first end of the receiver compensation capacitor is connected to the second input terminal of the synchronous rectification circuit through the receiver coil. The second end of the receiver compensation capacitor is connected to the first input terminal of the synchronous rectification circuit. The output terminal of the synchronous rectification circuit serves as the output terminal of the wireless charging receiver circuit and is connected to the load. The wireless charging receiver circuit is the circuit on the receiver side of the wireless charging system, i.e., the circuit on the side of the device being charged. The load is, for example, a low-dropout regulator (LDO) circuit or other voltage regulation circuit.

[0028] Figure 3 This paper shows one of the structural schematic diagrams of the overvoltage protection circuit provided in an embodiment of this application. (Refer to...) Figure 3As shown, the overvoltage protection circuit includes an overvoltage detection circuit 30 and a protection capacitor CP. The first terminal of the protection capacitor CP serves as the first connection terminal E1 of the overvoltage protection circuit, connected to the first terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit. The second terminal of the protection capacitor CP is connected to the first connection terminal of the overvoltage detection circuit 30. The second connection terminal of the overvoltage detection circuit 30 serves as the second connection terminal E2 of the overvoltage protection circuit, connected to the second terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit. The detection terminal of the overvoltage detection circuit 30 is connected to the positive output terminal VRECT of the wireless charging receiver circuit. The reference terminal of the overvoltage detection circuit 30 is used to input the protection voltage VOVP, which can be set according to the actual application.

[0029] The overvoltage detection circuit 30 is used to detect the voltage of the positive output terminal VRECT of the wireless charging receiver circuit. When it is determined that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit is greater than or equal to the protection voltage VOVP, the second terminal of the protection capacitor CP is connected to the second terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit to switch the protection capacitor CP.

[0030] At this time, the protection capacitor CP is connected in parallel with the receiving end compensation capacitor C2, which increases the compensation capacitance value of the receiving end. This can immediately change the resonance state of the entire wireless charging system, reduce the voltage transmission gain from the transmitter to the receiver, and thus quickly reduce the voltage output of the wireless charging receiver circuit to the load. In other words, it can quickly reduce the voltage of the positive output terminal VRECT of the wireless charging receiver circuit. This ensures that the voltage of the positive output terminal VRECT is less than the protection voltage VOVP during the communication delay phase. In this way, overvoltage protection of the receiving end circuit of the wireless charging system can be achieved before the overvoltage communication between the receiver and the transmitter.

[0031] based on Figure 3 In one embodiment of this application, the overvoltage protection circuit corresponding to the embodiment is as follows: Figure 4 This is a second schematic diagram of the overvoltage protection circuit provided in an embodiment of this application. (Refer to...) Figure 4 As shown, the overvoltage protection circuit includes an overvoltage detection circuit 30 and a protection capacitor CP. The overvoltage detection circuit 30 includes a comparator A31 and a switching circuit 32.

[0032] The first input terminal of comparator A31 serves as the detection terminal of the overvoltage detection circuit 30 and is connected to the positive output terminal VRECT of the wireless charging receiver circuit. The second input terminal of comparator A31 serves as the reference terminal of the overvoltage detection circuit 30 and is used to input the protection voltage VOVP. The output terminal of comparator A31 is connected to the controlled terminal of the switching circuit 32. The first terminal of the switching circuit 32 serves as the first connection terminal of the overvoltage detection circuit 30 and is connected to the second terminal of the protection capacitor CP. The second terminal of the switching circuit 32 serves as the second connection terminal of the overvoltage detection circuit 30 (that is, as the second connection terminal E2 of the overvoltage protection circuit) and is connected to the second terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit.

[0033] Comparator A31 detects the voltage at the positive output terminal VRECT of the wireless charging receiver circuit. When it determines that the voltage at VRECT is greater than the protection voltage VOVP, it controls switch circuit 32 to conduct. When switch circuit 32 is on, it connects the second terminal of the protection capacitor CP to the second terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit. At this time, the protection capacitor CP and the receiver compensation capacitor C2 are connected in parallel.

[0034] In this way, when the overvoltage detection circuit 30 detects an overvoltage at the positive output terminal VRECT of the wireless charging receiver circuit, it can immediately connect the protection capacitor CP in parallel across the two ends of the receiving compensation capacitor C2 of the wireless charging receiver circuit. This rapidly increases the compensation capacitor value at the receiving end, which can immediately change the resonant state of the entire wireless charging system, reduce the intrinsic resonant frequency, and thus reduce the voltage transmission gain from the transmitter to the receiver. This quickly reduces the voltage output by the wireless charging receiver circuit to the load, that is, it quickly reduces the voltage at the positive output terminal VRECT of the wireless charging receiver circuit. In this way, overvoltage protection of the wireless charging system receiver circuit can be achieved before the receiver and transmitter communicate overvoltage information.

[0035] For example, refer to Figure 4 As shown, the switching circuit 32 may include an N-type metal-oxide-semiconductor field-effect transistor (MOS transistor) SP1, the first input terminal of comparator A31 is the positive input terminal, and the second input terminal of comparator A31 is the negative input terminal.

[0036] The drain of the N-type MOSFET SP1 is connected to the second terminal of the protection capacitor CP as the first terminal of the switching circuit 32. The source of the N-type MOSFET SP1 is connected to the second terminal of the switching circuit 32 (that is, the second connection terminal E2 of the overvoltage protection circuit) and is used to connect to the second terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit. The gate of the N-type MOSFET SP1 is connected to the output terminal of the comparator A31 as the controlled terminal of the switching circuit 32.

[0037] When the comparator A31 determines that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit is greater than the protection voltage VOVP, it outputs a positive voltage drive signal to the gate of the N-type MOS transistor SP1 to control the N-type MOS transistor SP1 to turn on. At this time, the protection capacitor CP is connected in parallel with the receiver compensation capacitor C2.

[0038] For example, in one embodiment, the switching circuit 32 can also be implemented using a P-type MOS transistor.

[0039] Specifically, Figure 5 The third schematic diagram of the overvoltage protection circuit provided in this application embodiment is shown below. Figure 5 As shown, the overvoltage protection circuit includes an overvoltage detection circuit 30 and a protection capacitor CP. The overvoltage detection circuit 30 includes a comparator A31 and a switching circuit 32, which includes a P-type MOSFET SP2. The first input terminal of the comparator A31 is the negative input terminal, and the second input terminal of the comparator A31 is the positive input terminal. The comparator A31 can be a comparator powered by both positive and negative voltages.

[0040] The drain of the P-type MOSFET SP2 is connected to the second terminal of the protection capacitor CP as the first terminal of the switching circuit 32. The source of the P-type MOSFET SP2 is connected to the second terminal of the switching circuit 32 (that is, the second connection terminal E2 of the overvoltage protection circuit) and is used to connect to the second terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit. The gate of the P-type MOSFET SP2 is connected to the output terminal of the comparator A31 as the controlled terminal of the switching circuit 32.

[0041] When the comparator A31 determines that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit is greater than the protection voltage VOVP, it outputs a negative voltage drive signal to the gate of the P-type MOS transistor SP2 to control the P-type MOS transistor SP2 to turn on. At this time, the protection capacitor CP is connected in parallel with the receiver compensation capacitor C2.

[0042] Based on the overvoltage protection circuits of the above embodiments, in one embodiment of this application, when the voltage of the positive output terminal VRECT of the wireless charging receiver circuit is greater than the protection voltage VOVP, the voltage input to the reference terminal of the overvoltage detection circuit 30 switches from the protection voltage VOVP to the safety threshold voltage, which is the difference between the protection voltage VOVP and the preset safety hysteresis voltage VTH.

[0043] Correspondingly, the overvoltage detection circuit 30 is also used to disconnect the second terminal of the protection capacitor CP from the second terminal of the receiving compensation capacitor C2 of the wireless charging receiver circuit when it is determined that the voltage at the positive output terminal VRECT of the wireless charging receiver circuit is less than the safety threshold voltage, thereby disconnecting the protection capacitor CP. At this time, the system returns to the optimal operating state before the overvoltage.

[0044] For example, the protection voltage VOVP and the preset safety hysteresis voltage VTH can be set according to actual needs. For example, if the protection voltage VOVP is set to 20V and the preset safety hysteresis voltage VTH is set to 5V, then the safety threshold voltage is 15V. This application embodiment does not make any special limitation on this.

[0045] For example, with Figure 4 For example, comparator A31 detects the voltage of the positive output terminal VRECT of the wireless charging receiver circuit, compares the voltage of the positive output terminal VRECT with the protection voltage VOVP, and if it is determined that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit is greater than the protection voltage VOVP, it outputs a positive voltage drive signal to the gate of the N-type MOSFET SP1 to control the N-type MOSFET SP1 to turn on. At the same time, the voltage input to the negative input terminal of comparator A31 switches from the protection voltage VOVP to the safety threshold voltage.

[0046] When the N-type MOSFET SP1 is turned on, it connects the second terminal of the protection capacitor CP to the second terminal of the receiver compensation capacitor C2 in the wireless charging receiver circuit. At this time, the protection capacitor CP and the receiver compensation capacitor C2 are connected in parallel, rapidly increasing the compensation capacitance value at the receiver, reducing the intrinsic resonant frequency, and thus reducing the voltage transfer gain from the transmitter to the receiver. This quickly lowers the voltage output of the positive output terminal VRECT of the wireless charging receiver circuit. When the voltage at the positive output terminal VRECT of the wireless charging receiver circuit is lower than the safety threshold voltage, comparator A31 outputs a low-level signal to the gate of the N-type MOSFET SP1, controlling SP1 to turn off. This disconnects the parallel connection between the protection capacitor CP and the receiver compensation capacitor C2, and the system returns to its optimal operating state before the overvoltage.

[0047] Based on the overvoltage protection circuits of the above embodiments, in one embodiment of this application, the protection capacitor CP is at least one capacitor connected in parallel. The specific number of capacitors in the protection capacitor CP can be designed as needed to meet different capacitance values.

[0048] The overvoltage protection circuit provided in this embodiment is applied to a wireless charging receiver circuit. It includes an overvoltage detection circuit and a protection capacitor. The first terminal of the protection capacitor serves as the first connection terminal of the overvoltage protection circuit, connecting to the first terminal of the receiver compensation capacitor in the wireless charging receiver circuit. The second terminal of the protection capacitor is connected to the first connection terminal of the overvoltage detection circuit. The second connection terminal of the overvoltage detection circuit serves as the second connection terminal of the overvoltage protection circuit, connecting to the second terminal of the receiver compensation capacitor in the wireless charging receiver circuit. The detection terminal of the overvoltage detection circuit is connected to the positive output terminal of the wireless charging receiver circuit, and the reference terminal of the overvoltage detection circuit is used to input the protection voltage. Specifically, the overvoltage detection circuit detects the voltage at the positive output terminal of the wireless charging receiver circuit. When it determines that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than or equal to the protection voltage, it connects the second terminal of the protection capacitor to the second terminal of the receiver compensation capacitor to activate the protection capacitor. At this point, the protection capacitor is connected in parallel with the receiving end compensation capacitor, increasing the compensation capacitor value at the receiving end. This immediately changes the resonant state of the entire wireless charging system, reduces the system's intrinsic resonant frequency, and consequently lowers the voltage transmission gain from the transmitter to the receiver. This rapidly reduces the output voltage of the wireless charging receiver circuit, enabling overvoltage protection of the wireless charging system's receiving end circuit before overvoltage communication occurs between the receiver and transmitter. Furthermore, the active voltage gain adjustment scheme adopted in this embodiment, compared to related technologies that rely on bleed resistors or current source loads for energy dissipation, avoids heat release issues. It effectively reduces the heat generated during overvoltage protection, thus resolving the system temperature rise problem and the issue of insufficient bleed protection circuit capability leading to continuous overvoltage at the receiving end in severe overvoltage situations.

[0049] Based on the overvoltage protection circuits of the above embodiments, this application also provides a wireless charging receiver circuit. Figure 6 This paper shows one of the structural schematic diagrams of the wireless charging receiver circuit provided in an embodiment of this application. (Refer to...) Figure 6 As shown, the wireless charging receiver circuit may include a receiver coil L2, a receiver compensation capacitor C2, a synchronous rectification circuit 61, and an overvoltage protection circuit 62. The overvoltage protection circuit 62 includes an overvoltage detection circuit 30 and a protection capacitor CP.

[0050] The first end of the receiving end compensation capacitor C2 is connected to the second input end of the synchronous rectification circuit 61 through the receiving end coil L2. The second end of the receiving end compensation capacitor C2 is connected to the first input end of the synchronous rectification circuit 61. The output end of the synchronous rectification circuit 61 is connected to the load RL as the output end of the wireless charging receiving end circuit. The load RL is, for example, a voltage regulation circuit such as an LDO circuit.

[0051] The first terminal of the protection capacitor CP is connected to the first terminal E1 of the overvoltage protection circuit 62 and the first terminal of the receiving compensation capacitor C2. The second terminal of the protection capacitor CP is connected to the first terminal of the overvoltage detection circuit 30. The second terminal of the overvoltage detection circuit 30 is connected to the second terminal E2 of the overvoltage protection circuit 62 and the second terminal of the receiving compensation capacitor C2. The detection terminal of the overvoltage detection circuit 30 is connected to the positive output terminal VRECT of the synchronous rectifier circuit 61. The reference terminal of the overvoltage detection circuit 30 is used to input the protection voltage VOVP.

[0052] The overvoltage protection circuit 62 is the overvoltage protection circuit provided in any of the above embodiments of this application, and will not be described again here.

[0053] The synchronous rectifier circuit 61 can be an H-bridge rectifier circuit. The receiving coil L2 can induce the high-frequency AC power transmitted from the transmitting end. The synchronous rectifier circuit 61 can rectify the high-frequency AC power to obtain DC power, and then output the rectified DC power to the load RL connected to the synchronous rectifier circuit 61.

[0054] according to Figure 6 The wireless charging receiver circuit shown has an overvoltage detection circuit 30 that detects the voltage at the positive output terminal VRECT of the synchronous rectifier circuit 61, which is also the voltage at the positive output terminal VRECT of the wireless charging receiver circuit. When the voltage at the positive output terminal VRECT of the wireless charging receiver circuit is determined to be greater than or equal to the protection voltage VOVP, the second terminal of the protection capacitor CP is connected to the second terminal of the receiving compensation capacitor C2 in the wireless charging receiver circuit. At this time, the protection capacitor CP and the receiving compensation capacitor C2 are connected in parallel, and the compensation capacitance value at the receiving end becomes the sum of the capacitance values ​​of the receiving compensation capacitor C2 and the protection capacitor CP, instantly increasing the compensation capacitance value at the receiving end. The connection of the protection capacitor CP can immediately change the resonant state of the entire wireless charging system, reduce the voltage transmission gain from the transmitter to the receiver, and thus quickly reduce the voltage at the positive output terminal VRECT of the wireless charging receiver circuit. This ensures that the voltage at the positive output terminal VRECT is less than the protection voltage VOVP during the communication delay phase, thereby achieving overvoltage protection of the wireless charging system receiver circuit before overvoltage communication occurs between the receiver and transmitter.

[0055] based on Figure 6The wireless charging receiver circuit shown is as follows. Figure 7 This is a second schematic diagram of the wireless charging receiver circuit provided in an embodiment of this application. (Refer to...) Figure 7 As shown, the wireless charging receiver circuit may further include a controllable voltage source SI and a receiver controller 71. The output terminal of the controllable voltage source SI is connected to the reference terminal of the overvoltage detection circuit 30, and the controlled terminal of the controllable voltage source SI is connected to the first control terminal P1 of the receiver controller 71.

[0056] The receiver controller 71 is used to switch the voltage output from the controllable voltage source SI from the protection voltage VOVP to the safety threshold voltage VOTH when it detects that the voltage at the positive output terminal VRECT of the wireless charging receiver circuit is greater than the protection voltage VOVP. The safety threshold voltage VOTH is the difference between the protection voltage VOVP and the preset safety hysteresis voltage VTH.

[0057] For example, the receiver controller 71 can acquire the voltage of the positive output terminal VRECT of the wireless charging receiver circuit, and then compare the voltage of the positive output terminal VRECT with the protection voltage VOVP. When it is determined that the voltage of the positive output terminal VRECT is greater than the protection voltage VOVP, the first control terminal P1 controls the controllable voltage source SI to output the safety threshold voltage VOTH, and switches the voltage input to the reference terminal of the overvoltage detection circuit 30 from the protection voltage VOVP to the safety threshold voltage VOTH.

[0058] At this time, the overvoltage detection circuit 30 compares the voltage of the positive output terminal VRECT of the wireless charging receiver circuit with the safety threshold voltage VOTH. If it is determined that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit is less than the safety threshold voltage VOTH, the second terminal of the protection capacitor CP is disconnected from the second terminal of the receiving compensation capacitor C2 of the wireless charging receiver circuit, so as to disconnect the protection capacitor CP.

[0059] In this way, after the wireless charging receiver circuit triggers overvoltage protection, by switching the voltage input to the reference terminal of the overvoltage detection circuit 30 from the protection voltage VOVP to the safety threshold voltage VOTH, the overvoltage detection circuit 30 compares the voltage of the positive output terminal VRECT of the wireless charging receiver circuit with the safety threshold voltage VOTH. Based on the comparison result, it determines whether to cut off the protection capacitor CP. This ensures that when the voltage of the positive output terminal VRECT of the wireless charging receiver circuit drops to a certain level, the system returns to its original optimal resonant operating state.

[0060] For example, in combination Figure 4The receiver controller 71 can also directly acquire the signal from the output of comparator A31. When the output of comparator A31 outputs a positive voltage drive signal, the receiver controller 71 can directly determine that the voltage of the positive output of the wireless charging receiver circuit VRECT is greater than the protection voltage VOVP. At this time, the first control terminal P1 controls the controllable voltage source SI to output the safety threshold voltage VOTH, and switches the voltage input to the reference terminal of the overvoltage detection circuit 30 from the protection voltage VOVP to the safety threshold voltage VOTH.

[0061] Or, combine Figure 5 When the output of comparator A31 outputs a negative voltage drive signal, the receiver controller 71 can directly determine that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit is greater than the protection voltage VOVP.

[0062] Based on the above embodiments, this application also provides a wireless charging system, which includes a wireless charging transmitter circuit and a wireless charging receiver circuit as described in any of the above embodiments; wherein, the wireless charging transmitter circuit is a circuit on the charger or charging platform side, and the wireless charging receiver circuit is a circuit on the charging device side. The wireless charging transmitter circuit and the wireless charging receiver circuit are coupled through the transmitter coil of the wireless charging transmitter circuit and the receiver coil of the wireless charging receiver circuit. Energy transfer and communication signal transfer between the transmitter and receiver can be achieved through coil coupling. The energy transfer can be unidirectional or bidirectional.

[0063] For example, Figure 8 This paper shows one of the structural schematic diagrams of a wireless charging system provided in an embodiment of this application. (Refer to...) Figure 8 As shown, the wireless charging system includes a wireless charging transmitter circuit 81 and a wireless charging receiver circuit 82. The wireless charging transmitter circuit 81 may include a DC power supply Vin, an inverter bridge circuit 811, a transmitter compensation capacitor C1, and a transmitter coil L1. The DC power supply Vin is connected between the two input terminals of the inverter bridge circuit 811, and the transmitter compensation capacitor C1 and the transmitter coil L1 are connected in series between the midpoints of the two bridge arms of the inverter bridge circuit 811.

[0064] The wireless charging receiver circuit 82 may include an overvoltage protection circuit 62, a receiver coil L2, a receiver compensation capacitor C2, and a synchronous rectification circuit 61. The overvoltage protection circuit 62 may include an overvoltage detection circuit 30 and a protection capacitor CP. The first end of the receiver compensation capacitor C2 is connected to the second input end of the synchronous rectification circuit 61 via the receiver coil L2. The second end of the receiver compensation capacitor C2 is connected to the first input end of the synchronous rectification circuit 61. The output end of the synchronous rectification circuit 61 serves as the output end of the wireless charging receiver circuit 82 and is connected to the load RL. The first end of the protection capacitor CP serves as the first connection end E1 of the overvoltage protection circuit 62 and is connected to the first end of the receiver compensation capacitor C2. The second end of the protection capacitor CP is connected to the first connection end of the overvoltage detection circuit 30. The second connection end of the overvoltage detection circuit 30 serves as the second connection end E2 of the overvoltage protection circuit 62 and is connected to the second end of the receiver compensation capacitor C2. The detection end of the overvoltage detection circuit 30 is connected to the positive output end VRECT of the synchronous rectification circuit 61. The reference end of the overvoltage detection circuit 30 is used to input the protection voltage VOVP.

[0065] The wireless charging transmitter circuit 81 and the wireless charging receiver circuit 82 are coupled through the transmitter coil L1 and the receiver coil L2.

[0066] according to Figure 8 In the wireless charging system shown, the DC power supply Vin of the wireless charging transmitter circuit 81 can provide energy. The DC voltage provided by Vin is converted into AC power by the inverter bridge circuit 811, which drives the resonant circuit composed of the transmitter compensation capacitor C1 and the transmitter coil L1 to generate a high-frequency magnetic field. According to the law of electromagnetic induction, the receiver coil L2 of the wireless charging receiver circuit 82 can induce a high-frequency AC power. This high-frequency AC power enters the synchronous rectifier circuit 61 after passing through the receiver compensation capacitor C2, and is then rectified and output to the load RL.

[0067] The overvoltage detection circuit 30 in the overvoltage protection circuit 62 can detect the voltage of the positive output terminal VRECT of the synchronous rectifier circuit 61, that is, detect the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82, and compare the voltage of the positive output terminal VRECT with the protection voltage VOVP input to the reference terminal. If it is determined that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82 is greater than or equal to the protection voltage VOVP, the second terminal of the protection capacitor CP is connected to the second terminal of the receiver compensation capacitor C2. At this time, the protection capacitor CP and the receiver compensation capacitor C2 are connected in parallel. Since the wireless charging system originally operates at the optimal resonant frequency, when the wireless charging receiver circuit 82 triggers an overvoltage, the compensation capacitor value of the receiver becomes the sum of the compensation capacitor C2 and the protection capacitor CP. The added protection capacitor CP can drastically increase the compensation capacitor value of the receiver. At this time, the addition of the protection capacitor CP can immediately change the resonant state of the entire wireless charging system, reduce the gain of the wireless charging system, and thus quickly reduce the voltage of the positive output terminal VRECT of the wireless charging receiver circuit. This ensures that the voltage of the positive output terminal VRECT is less than the protection voltage VOVP during the communication delay phase. In this way, overvoltage protection of the receiver of the wireless charging system can be achieved before the overvoltage communication between the receiver and the transmitter.

[0068] For example, based on Figure 8 , Figure 9 This is a second schematic diagram of the wireless charging system provided in an embodiment of this application, with reference to... Figure 9 As shown, the wireless charging system may include a wireless charging transmitter circuit 81 and a wireless charging receiver circuit 82.

[0069] The wireless charging transmitter circuit 81 may include a DC power supply Vin, an inverter bridge circuit 811, a transmitter compensation capacitor C1, a transmitter coil L1, a detection circuit 812, a demodulation circuit 813, and a transmitter controller 814. The inverter bridge circuit 811 includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The drains of the first switch S1 and the third switch S3 are connected to the positive terminal of the DC power supply Vin. The sources of the second switch S2 and the fourth switch S4 are connected to a first ground GND1. The source of the first switch S1 and the drain of the second switch S2 are connected, and the source of the third switch S3 and the drain of the fourth switch S4 are connected. Specifically, the first switch S1 and the second switch S2 are connected in series to form the first bridge arm of the inverter bridge circuit 811, and the third switch S3 and the fourth switch S4 are connected in series to form the second bridge arm of the inverter bridge circuit 811. The transmitter compensation capacitor C1 and the transmitter coil L1 are connected in series between the midpoint B1 of the first bridge arm and the midpoint B2 of the second bridge arm.

[0070] The wireless charging receiver circuit 82 may include an overvoltage protection circuit 62, a receiver coil L2, a receiver compensation capacitor C2, a synchronous rectification circuit 61, an output capacitor C0, a controllable voltage source S1, a receiver controller 71, and a modulation circuit 821. The overvoltage protection circuit 62 includes an overvoltage detection circuit 30 and a protection capacitor CP. The overvoltage detection circuit 30 may include an N-type MOSFET SP1 and a comparator A31. The drain of the N-type MOSFET SP1 is connected to the second terminal of the protection capacitor CP, the source of the N-type MOSFET SP1 is connected to the second terminal of the receiver compensation capacitor C2, and the gate of the N-type MOSFET SP1 is connected to the output terminal of the comparator A31.

[0071] The positive input terminal of comparator A31 is connected to the positive output terminal VRECT of synchronous rectifier circuit 61 (which is also the positive output terminal VRECT of wireless charging receiver circuit 82), the negative input terminal of comparator A31 is connected to the output terminal of controllable voltage source SI, and the controlled terminal of controllable voltage source SI is connected to the first control terminal P1 of receiver controller 71.

[0072] The synchronous rectification circuit 61 includes a fifth switch SR1, a sixth switch SR2, a seventh switch SR3, and an eighth switch SR4. The drains of the fifth switch SR1 and the seventh switch SR3 are connected together to serve as the positive output terminal VRECT of the wireless charging receiver circuit 82. The sources of the sixth switch SR2 and the eighth switch SR4 are connected to the second ground GND2. The fifth switch SR1 and the sixth switch SR2 are connected in series to form the first bridge arm of the synchronous rectification circuit 61, and the seventh switch SR3 and the eighth switch SR4 are connected in series to form the second bridge arm of the synchronous rectification circuit 61. The first end of the receiver compensation capacitor C2 is connected to the second input terminal of the synchronous rectification circuit 61 (i.e., the midpoint H2 of the second bridge arm of the synchronous rectification circuit 61) through the receiver coil L2. The second end of the receiver compensation capacitor C2 is connected to the first input terminal of the synchronous rectification circuit 61 (i.e., the midpoint H1 of the first bridge arm of the synchronous rectification circuit 61). The output terminal of the synchronous rectification circuit 61 is connected to the load RL as the output terminal of the wireless charging receiver circuit 82. The output capacitor C0 is connected between the output terminals of the synchronous rectifier circuit 61, that is, between the positive output terminal VRECT of the wireless charging receiver circuit 82 and the second ground GND2.

[0073] The wireless charging transmitter circuit 81 and the wireless charging receiver circuit 82 are coupled through the transmitter coil L1 and the receiver coil L2, where k represents the coupling coefficient.

[0074] For example, the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 in the inverter bridge circuit 811 can be switches with anti-parallel diodes, such as N-type MOS transistors with anti-parallel diodes.

[0075] For example, the fifth switch SR1, the sixth switch SR2, the seventh switch SR3 and the eighth switch SR4 in the synchronous rectifier circuit 61 are rectifier switches, which can be switches with anti-parallel diodes, such as N-type MOS transistors with anti-parallel diodes.

[0076] according to Figure 9 In the wireless charging system shown, the DC power supply Vin of the wireless charging transmitter circuit 81 can provide energy. The DC voltage provided by Vin is converted into AC power by the inverter bridge circuit 811, which drives the resonant circuit composed of the transmitter compensation capacitor C1 and the transmitter coil L1 to generate a high-frequency magnetic field. According to the law of electromagnetic induction, the receiver coil L2 of the wireless charging receiver circuit 82 can induce a high-frequency AC power. This high-frequency AC power enters the synchronous rectifier circuit 61 after passing through the receiver compensation capacitor C2, and is then rectified and output to the load RL.

[0077] Comparator A31 acquires the voltage of the positive output terminal VRECT of the synchronous rectifier circuit 61, which is also the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82. It compares the voltage of the positive output terminal VRECT with the protection voltage VOVP input to the negative phase input terminal of the controllable voltage source SI. If it is determined that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82 is greater than or equal to the protection voltage VOVP, it is determined that the wireless charging receiver circuit 82 is overvoltage, and the overvoltage protection is triggered. A positive voltage drive signal is output to the gate of the N-type MOSFET SP1 to control the N-type MOSFET SP1 to turn on. At this time, the protection capacitor CP is connected in parallel with the receiver compensation capacitor C2. Since the wireless charging system originally operates at the optimal resonant frequency, when the wireless charging receiver circuit 82 triggers overvoltage protection, the compensation capacitor value at the receiver becomes the sum of the compensation capacitor C2 and the protection capacitor CP. The added protection capacitor CP will drastically increase the compensation capacitor value at the receiver. At this time, the intrinsic resonant frequency of the wireless charging system will decrease, thereby reducing the transmission gain of the system and quickly lowering the voltage at the positive output terminal VRECT of the wireless charging receiver circuit 82. At the same time, since the gain of the wireless charging system is reduced, it can be ensured that the voltage at the positive output terminal VRECT of the wireless charging receiver circuit 82 is less than the VOVP voltage during the communication delay phase.

[0078] During this process, the receiver controller 71 can simultaneously acquire the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82 and compare it with the set protection voltage VOVP. If the voltage of the positive output terminal VRECT is determined to be greater than or equal to the set protection voltage VOVP, the output voltage of the controllable voltage source SI is switched from the protection voltage VOVP to the safety threshold voltage VOTH. At the same time, overvoltage information of the positive output terminal VRECT can be obtained. After the protection capacitor CP is connected across the compensation capacitor C2, the receiver controller 71 starts to continuously send overvoltage information to the wireless charging transmitter circuit 81. After the wireless charging transmitter circuit 81 demodulates the overvoltage information, it immediately reduces the energy of the transmitter, which further reduces the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82.

[0079] Specifically, the receiver controller 71 can send the overvoltage information to the modulation circuit 821 for modulation and encoding. The modulation circuit 821 loads the modulated and encoded overvoltage information into the energy transmission channel and uses the electromagnetic field coupling between the wireless charging transmitter circuit 81 and the wireless charging receiver circuit 82 to send the modulated and encoded overvoltage information to the wireless charging transmitter circuit 81. The detection circuit 812 in the wireless charging transmitter circuit 81 can detect the modulated and encoded overvoltage information transmitted by the wireless charging receiver circuit 82 from the resonant cavity of the wireless charging transmitter circuit 81. After the demodulation circuit 813 decodes the modulated and encoded overvoltage information, it can obtain the overvoltage information and send it to the transmitter controller 814. The transmitter controller 814 can further reduce the energy transmitted from the wireless charging transmitter circuit 81 to the wireless charging receiver circuit 82 based on the demodulated overvoltage information, so that the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82 is further reduced.

[0080] After the protection capacitor CP is connected across the compensation capacitor C2 at the receiving end, the comparator A31 compares the voltage of the positive output terminal VRECT sampled at the non-inverting input terminal with the safety threshold voltage VOTH input from the controllable voltage source SI to the negative input terminal. When the voltage of the positive output terminal VRECT of the wireless charging receiver circuit 82 is less than the safety threshold voltage VOTH, the comparator A31 outputs a low-level signal to the gate of the N-type MOS transistor SP1 to control the N-type MOS transistor SP1 to turn off. At this time, the protection capacitor CP is disconnected from the compensation capacitor C2 at the receiving end, so that the system returns to the optimal resonance working state.

[0081] The wireless charging system provided in this application, when detecting an overvoltage at the positive output terminal VRECT of the wireless charging receiver circuit, inserts an additional protective capacitor across the compensation capacitor at the receiver. This drastically increases the compensation capacitor value at the receiver, immediately altering the resonant state of the entire wireless charging system, reducing the transmission gain, and thus rapidly lowering the voltage at the positive output terminal VRECT. Simultaneously, after inserting the protective capacitor, the receiver can continuously send overvoltage information to the transmitter without interruption. Upon receiving the overvoltage information, the transmitter reduces energy transmission on the primary side, further lowering the voltage at the positive output terminal VRECT. The protective capacitor is disconnected when the voltage at the positive output terminal VRECT falls below the safety threshold voltage, allowing the system to return to its original optimal resonant operating state. This ensures that the voltage at the positive output terminal VRECT of the wireless charging receiver circuit is below the protection voltage during the communication delay phase, enabling overvoltage protection at the receiver before overvoltage communication occurs between the receiver and transmitter.

[0082] The wireless charging system provided in this application embodiment directly reduces the voltage at the positive output terminal VRECT of the wireless charging receiver circuit by actively adjusting the system's resonant state and transmission gain, thus achieving overvoltage protection at the receiver. Compared to passive energy dissipation schemes, this avoids the problem of system overheating or even thermal damage that may occur during overvoltage protection. It also avoids the situation where the receiver experiences continuous overvoltage due to insufficient dissipation protection circuit capability in severe overvoltage cases, effectively improving the system's overvoltage protection capability.

[0083] This application also provides a chip that includes an overvoltage protection circuit as provided in any of the above embodiments, or a wireless charging receiver circuit as provided in any of the above embodiments. This chip can detect the voltage output by the receiver in the wireless charging system. When it is determined that the voltage output by the receiver is greater than or equal to a set protection voltage, it switches the protection capacitor to the receiver compensation capacitor, that is, connects the protection capacitor in parallel across the receiver compensation capacitor, rapidly increasing the value of the receiver compensation capacitor, thereby reducing the intrinsic resonant frequency of the wireless charging system, and thus quickly reducing the voltage output by the receiver, achieving overvoltage protection for the receiver. Moreover, compared to energy dissipation schemes in related technologies, it does not introduce heat release problems, effectively reducing the heat generated during overvoltage protection, thereby solving the system temperature rise problem and the situation where the dissipation protection circuit is insufficient in severe overvoltage cases, causing continuous overvoltage at the receiver.

[0084] This application also provides an electronic device, which includes an overvoltage protection circuit as provided in any of the above embodiments, or a wireless charging receiver circuit as provided in any of the above embodiments, or a chip as described above. The electronic device is an electronic device on the charging side, and may include at least one of the following: mobile phone, wearable device, laptop computer, tablet computer, wireless headset, in-vehicle device, smart home device, virtual reality (VR) terminal device, and augmented reality (AR) terminal device, but is not limited thereto. The electronic device can detect the voltage output by the wireless charging receiver circuit. When it is determined that the voltage is greater than or equal to a set protection voltage, it switches the protection capacitor to the receiver compensation capacitor, that is, connects the protection capacitor in parallel across the receiver compensation capacitor, rapidly increasing the compensation capacitor value of the wireless charging receiver circuit, thereby reducing the intrinsic resonant frequency of the wireless charging system, and thus quickly reducing the output voltage of the wireless charging receiver circuit, achieving overvoltage protection for the wireless charging receiver circuit. Moreover, compared to energy release solutions in related technologies, this method does not introduce heat release issues, effectively reducing the heat generated during overvoltage protection. This solves the problem of system temperature rise and the situation where insufficient discharge protection circuit capability causes continuous overvoltage in electronic devices during wireless charging under severe overvoltage conditions.

[0085] In one embodiment of this application, the electronic device may include a processor, an external memory interface, internal memory, a Universal Serial Bus (USB) interface, a charging management module, a power management module, a battery, an antenna, a mobile communication module, a wireless communication module, an audio module, a speaker, a microphone, a headphone jack, a sensor module, buttons, a motor, an indicator, a camera, a display screen, and a Subscriber Identification Module (SIM) card interface, etc. The sensor module may include motion sensors and gyroscopes, etc.

[0086] It is understood that the structures exemplified in the embodiments of this application do not constitute a specific limitation on the electronic device. In other embodiments of this application, the electronic device may include more or fewer components, or combine some components, or split some components, or have different component arrangements. These components may be implemented in hardware, software, or a combination of software and hardware.

[0087] The processor may include one or more processing units, such as, but not limited to, an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and a neural network processing unit (NPU). Different processing units may be independent devices or integrated into one or more processors. The controller can generate operation control signals based on instruction opcodes and timing signals to control instruction fetching and execution. The processor may also include memory for storing instructions and data. In some embodiments, the memory in the processor may be a cache memory. This memory can store instructions or data that the processor has just used or that are used repeatedly. If the processor needs to reuse the instruction or data, it can retrieve it from memory. This avoids repeated accesses, reduces processor waiting time, and thus improves system efficiency.

[0088] The charging management module receives charging signals from a charger, which may include a wireless charger. In some wireless charging embodiments, the charging management module includes a wireless charging receiver circuit, which receives wireless charging input through its receiving coil. While charging the battery, the charging management module can also supply power to the electronic device via the power management module.

[0089] The power management module connects the battery, the charging management module, and the processor. It receives input from the battery and / or the charging management module to power the processor, internal memory, display screen, camera, and wireless communication module. The power management module can also monitor parameters such as battery capacity, battery cycle count, and battery health status (leakage current, impedance). In some embodiments, the power management module may be located within the processor. In other embodiments, the power management module and the charging management module may be located in the same device.

[0090] Wireless communication functionality in electronic devices can be implemented through antennas, mobile communication modules, wireless communication modules, modem processors, and baseband processors. Antennas are used to transmit and receive electromagnetic wave signals. Mobile communication modules can provide solutions for wireless communication applications in electronic devices, including 2G / 3G / 4G / 5G. In some embodiments, at least some functional modules of the mobile communication module can be housed in the same device as at least some modules of the processor.

[0091] Wireless communication modules can provide solutions for at least one of the following wireless communication technologies used in electronic devices: Wireless Local Area Networks (WLANs) (such as Wireless Fidelity (Wi-Fi) networks), Bluetooth (BT), Global Navigation Satellite System (GNSS), Frequency Modulation (FM), Near Field Communication (NFC), and Infrared (IR), but are not limited to these. A wireless communication module can be one or more devices integrating at least one communication processing module. The wireless communication module receives electromagnetic waves via an antenna, modulates and filters the electromagnetic wave signal, and sends the processed signal to a processor. The wireless communication module can also receive signals to be transmitted from the processor, modulate and amplify them, and then radiate them as electromagnetic waves via the antenna.

[0092] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations thereof that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

Claims

1. An overvoltage protection circuit, characterized in that, This invention relates to a wireless charging receiver circuit, comprising a receiver coil, a receiver compensation capacitor, and a synchronous rectification circuit. The first end of the receiver compensation capacitor is connected to the second input terminal of the synchronous rectification circuit via the receiver coil. The second end of the receiver compensation capacitor is connected to the first input terminal of the synchronous rectification circuit. The output terminal of the synchronous rectification circuit serves as the output terminal of the wireless charging receiver circuit and is connected to the load. The overvoltage protection circuit includes an overvoltage detection circuit and a protection capacitor. The first end of the protection capacitor serves as the first connection terminal of the overvoltage protection circuit and is connected to the first end of the receiving end compensation capacitor; the second end of the protection capacitor is connected to the first connection terminal of the overvoltage detection circuit. The second connection terminal of the overvoltage detection circuit serves as the second connection terminal of the overvoltage protection circuit and is connected to the second terminal of the compensation capacitor at the receiving end. The detection terminal of the overvoltage detection circuit is connected to the positive output terminal of the wireless charging receiving end circuit, and the reference terminal of the overvoltage detection circuit is used to input the protection voltage. The overvoltage detection circuit is used to detect the voltage at the positive output terminal of the wireless charging receiver circuit. When it is determined that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than or equal to the protection voltage, the second terminal of the protection capacitor is connected to the second terminal of the receiver compensation capacitor to switch the protection capacitor.

2. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage detection circuit includes a comparator and a switching circuit; The first input terminal of the comparator serves as the detection terminal of the overvoltage detection circuit and is connected to the positive output terminal of the wireless charging receiver circuit. The second input terminal of the comparator serves as the reference terminal of the overvoltage detection circuit and is used to input the protection voltage. The output terminal of the comparator is connected to the controlled terminal of the switching circuit. The first terminal of the switching circuit is connected to the second terminal of the protection capacitor as the first connection terminal of the overvoltage detection circuit, and the second terminal of the switching circuit is connected to the second terminal of the receiving compensation capacitor as the second connection terminal of the overvoltage detection circuit. The comparator is used to detect the voltage at the positive output terminal of the wireless charging receiver circuit. When it is determined that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, the comparator controls the switching circuit to turn on. When the switching circuit is turned on, it connects the second terminal of the protection capacitor with the second terminal of the receiver compensation capacitor.

3. The overvoltage protection circuit according to claim 2, characterized in that, The switching circuit includes an N-type MOSFET, the first input terminal of the comparator is the positive input terminal, and the second input terminal of the comparator is the negative input terminal; The drain of the N-type MOS transistor is connected to the second terminal of the protection capacitor as the first terminal of the switching circuit. The source of the N-type MOS transistor is connected to the second terminal of the receiving compensation capacitor in the wireless charging receiver circuit as the second terminal of the switching circuit. The gate of the N-type MOS transistor is connected to the output terminal of the comparator as the controlled terminal of the switching circuit. When the comparator determines that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, it outputs a positive voltage drive signal to the gate of the N-type MOS transistor to control the N-type MOS transistor to turn on.

4. The overvoltage protection circuit according to claim 2, characterized in that, The switching circuit includes a P-type MOS transistor, the first input terminal of the comparator is the negative input terminal, and the second input terminal of the comparator is the positive input terminal; The drain of the P-type MOS transistor is connected to the second terminal of the protection capacitor as the first terminal of the switching circuit. The source of the P-type MOS transistor is connected to the second terminal of the receiving compensation capacitor in the wireless charging receiver circuit as the second terminal of the switching circuit. The gate of the P-type MOS transistor is connected to the output terminal of the comparator as the controlled terminal of the switching circuit. When the comparator determines that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, it outputs a negative voltage drive signal to the gate of the P-type MOS transistor to control the P-type MOS transistor to turn on.

5. The overvoltage protection circuit according to any one of claims 1 to 4, characterized in that, When the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage, the voltage input to the reference terminal of the overvoltage detection circuit switches from the protection voltage to the safety threshold voltage. The safety threshold voltage is the difference between the protection voltage and the preset safety hysteresis voltage; The overvoltage detection circuit is further configured to disconnect the second terminal of the protection capacitor from the second terminal of the receiver compensation capacitor when it is determined that the voltage at the positive output terminal of the wireless charging receiver circuit is less than the safety threshold voltage, thereby disconnecting the protection capacitor.

6. The overvoltage protection circuit according to any one of claims 1 to 4, characterized in that, The protective capacitor is at least one capacitor, and the at least one capacitor is connected in parallel.

7. A wireless charging receiver circuit, characterized in that, It includes a receiving coil, a receiving compensation capacitor, a synchronous rectification circuit, and an overvoltage protection circuit as described in any one of claims 1 to 6, wherein the overvoltage protection circuit includes an overvoltage detection circuit and a protection capacitor; The first end of the receiving end compensation capacitor is connected to the second input end of the synchronous rectification circuit through the receiving end coil. The second end of the receiving end compensation capacitor is connected to the first input end of the synchronous rectification circuit. The output end of the synchronous rectification circuit serves as the output end of the wireless charging receiving end circuit. The first end of the protection capacitor is connected to the first end of the receiving end compensation capacitor, and the second end of the protection capacitor is connected to the first connection end of the overvoltage detection circuit; the second connection end of the overvoltage detection circuit is connected to the second end of the receiving end compensation capacitor, the detection end of the overvoltage detection circuit is connected to the positive output end of the synchronous rectification circuit, and the reference end of the overvoltage detection circuit is used to input the protection voltage.

8. The wireless charging receiver circuit according to claim 7, characterized in that, The wireless charging receiver circuit also includes a controllable voltage source and a receiver controller. The output terminal of the controllable voltage source is connected to the reference terminal of the overvoltage detection circuit, and the controlled terminal of the controllable voltage source is connected to the first control terminal of the receiver controller. The receiver controller is used to switch the voltage output from the controllable voltage source from the protection voltage to the safety threshold voltage when it detects that the voltage at the positive output terminal of the wireless charging receiver circuit is greater than the protection voltage. The safety threshold voltage is the difference between the protection voltage and the preset safety hysteresis voltage.

9. A wireless charging system, characterized in that, It includes a wireless charging transmitter circuit and a wireless charging receiver circuit as described in claim 7 or 8; the wireless charging transmitter circuit and the wireless charging receiver circuit are coupled through the transmitter coil of the wireless charging transmitter circuit and the receiver coil of the wireless charging receiver circuit.

10. A chip, characterized in that, It includes the overvoltage protection circuit as described in any one of claims 1 to 6, or the wireless charging receiver circuit as described in claim 7 or 8.

11. An electronic device, characterized in that, It includes the overvoltage protection circuit as described in any one of claims 1 to 6, or the wireless charging receiver circuit as described in claim 7 or 8, or the chip as described in claim 10.

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