An overvoltage protection circuit, a power receiver, and a power transmission device

Abstract

The application relates to an overvoltage protection circuit, a power receiver and a power transmission device, each protection branch of the overvoltage protection circuit comprising an overvoltage detection circuit and a driving circuit, when the input end of a rectifier bridge or the output end of the rectifier bridge is overvoltage, the overvoltage detection circuit sends a first level signal to the driving circuit, so that the driving circuit drives the upper transistor or the lower transistor in the rectifier bridge to be turned on according to the first level signal, to form a loop in the rectifier bridge, release the overvoltage energy, protect the rectifier bridge, and the overvoltage protection circuit releases the overvoltage energy by actively turning on the MOS transistor in the rectifier bridge, greatly improves the voltage limiting capacity, and saves the chip size.

Description

Technical Field

[0001] This invention relates to the field of overvoltage protection, and in particular to an overvoltage protection circuit, a power receiver, and a power transmission device. Background Technology

[0002] A power receiver includes a rectifier bridge, which contains power switching transistors. To provide overvoltage protection for these transistors, the voltage at the output node of the rectifier bridge is typically limited. Traditional overvoltage protection methods involve adding a load, such as a dummy load or a snubber resistor, to the output node of the rectifier bridge. The added load dissipates some power, thereby reducing the voltage at the output node below the damage voltage of the power switching transistors.

[0003] However, traditional overvoltage protection schemes have limited voltage limiting capabilities due to the limited increase in load resistance and limited power consumption. Furthermore, the increased load is located outside the chip, which increases the size of the external package and restricts PCB layout. Summary of the Invention

[0004] The present invention aims to provide an overvoltage protection circuit, a power receiver, and a power transmission device, which can provide overvoltage protection for the rectifier bridge in the power receiver and improve voltage limiting capability.

[0005] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions:

[0006] In a first aspect, embodiments of the present invention provide an overvoltage protection circuit applied to a power receiver. The power receiver includes a rectifier bridge, which includes a first bridge branch and a second bridge branch. The rectifier bridge includes a first input terminal and a second input terminal. The first input terminal of the rectifier bridge is located at the common node of the upper-level transistor and the lower-level transistor in the first bridge branch. The second input terminal of the rectifier bridge is located at the common node of the upper-level transistor in the first bridge branch and the upper-level transistor in the second bridge branch. The overvoltage protection circuit includes a first protection branch and a second protection branch.

[0007] The input terminal of the first protection branch is connected to the first input terminal of the rectifier bridge, and the input terminal of the second protection branch is connected to the second input terminal of the rectifier bridge; or, the input terminals of both the first protection branch and the second protection branch are connected to the output terminal of the rectifier bridge.

[0008] The output terminal of the first protection branch is connected to the control terminal of the upper-level tube in the first bridge branch, and the output terminal of the second protection branch is connected to the control terminal of the upper-level tube in the second bridge branch; or, the output terminal of the first protection branch is connected to the control terminal of the lower-level tube in the first bridge branch, and the output terminal of the second protection branch is connected to the control terminal of the lower-level tube in the second bridge branch.

[0009] Each protection branch includes an overvoltage detection circuit and a drive circuit;

[0010] The input terminal of the overvoltage detection circuit serves as the input terminal of each protection branch, and the output terminal of the overvoltage detection circuit is connected to the first terminal of the drive circuit. When the input terminal or the output terminal of the rectifier bridge is overvoltageed, the overvoltage detection circuit sends a first level signal to the drive circuit.

[0011] The second end of the driving circuit serves as the output end of each protection branch, and the driving circuit is used to drive the upper transistor or the lower transistor to conduct according to the first level signal.

[0012] In some embodiments, the overvoltage detection circuit includes a voltage regulator unit and a voltage divider unit;

[0013] The first terminal of the voltage regulator unit serves as the input terminal of the overvoltage detection circuit, and the second terminal of the voltage regulator unit is connected to the first terminal of the voltage divider unit. The voltage regulator unit is used to output a stable voltage signal when the input terminal or the output terminal of the rectifier bridge is overvoltaged.

[0014] The second terminal of the voltage divider unit is grounded, and the third terminal of the voltage divider unit is connected to the first terminal of the driving circuit. The voltage divider unit is used to divide the voltage according to the input voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal, or to divide the voltage according to the output voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal.

[0015] In some embodiments, the voltage regulating unit includes a plurality of Zener diodes connected in series, and the voltage dividing unit includes a first resistor;

[0016] The cathode of the first Zener diode among the plurality of Zener diodes serves as the first terminal of the voltage regulation unit. The anode of the last Zener diode among the plurality of Zener diodes is connected to one end of the first resistor and the first terminal of the driving circuit, respectively. The other end of the first resistor is grounded.

[0017] In some embodiments, the driving circuit includes an OR gate unit;

[0018] The power supply terminal of the OR gate unit is connected to the first DC power supply, the first input terminal of the OR gate unit is used to receive the first control signal of the rectifier bridge, the second input terminal of the OR gate unit is connected to the output terminal of the overvoltage detection circuit, and the output terminal of the OR gate unit serves as the second terminal of the drive circuit.

[0019] The OR gate unit is used to perform an OR operation on the first level signal and the first control signal, and output a second control signal to drive the upper-level transistor or the lower-level transistor to conduct.

[0020] In some embodiments, the driving circuit further includes a first unidirectional conduction unit;

[0021] The first terminal of the first unidirectional conduction unit is connected to the first DC power supply, and the second terminal of the first unidirectional conduction unit is connected to the power supply terminal of the OR gate unit. The first unidirectional conduction unit is used to prevent the control terminal voltage of the upper transistor or the control terminal voltage of the lower transistor from leaking to the first DC power supply.

[0022] In some embodiments, the OR gate unit includes a first OR gate, and the first unidirectional conduction unit includes a first diode;

[0023] The power supply terminal of the first OR gate is connected to the cathode of the first diode, and the anode of the first diode is used to connect to the first DC power supply.

[0024] The first input terminal of the first OR gate is used to receive the first control signal of the rectifier bridge, the second input terminal of the first OR gate is connected to the output terminal of the overvoltage detection circuit, and the output terminal of the first OR gate serves as the second terminal of the drive circuit.

[0025] In some embodiments, the driving circuit further includes a second unidirectional conduction unit;

[0026] The first end of the second unidirectional conduction unit is connected to the output end of the overvoltage detection circuit, and the second end of the second unidirectional conduction unit serves as the second end of the driving circuit. The second unidirectional conduction unit is used to output a conduction signal according to the first level signal to drive the upper transistor or the lower transistor to conduct.

[0027] In some embodiments, the second unidirectional conduction unit includes a second diode;

[0028] The anode of the second diode is connected to the output terminal of the overvoltage detection circuit, and the cathode of the second diode serves as the second terminal of the driving circuit.

[0029] In a second aspect, embodiments of the present invention provide a power receiver, comprising:

[0030] A receiving coil, used for coupling to a transmitting coil;

[0031] A rectifier bridge is connected to the receiving coil; and,

[0032] As described above, the overvoltage protection circuit is used to drive the upper or lower transistor of the rectifier bridge to conduct when the rectifier bridge is overvoltaged.

[0033] In a third aspect, embodiments of the present invention provide a wireless power transmission device, including a power transmitter and a power receiver as described above, wherein the power transmitter includes a transmitting coil and is used to couple electrical energy to the receiving coil via the transmitting coil.

[0034] In a fourth aspect, embodiments of the present invention provide an overvoltage protection circuit applied to a power receiver. The power receiver includes a rectifier bridge, which includes a first bridge branch and a second bridge branch. The input terminal of the rectifier bridge includes a first input terminal, which is located at the common node of the upper transistor and the lower transistor in the first bridge branch. The output terminal of the rectifier bridge is located at the common node of the upper transistor in the first bridge branch and the upper transistor in the second bridge branch. The upper transistor in the first bridge branch is normally open, and the lower transistor in the first bridge branch is normally closed.

[0035] The input terminal of the overvoltage protection circuit is connected to the second input terminal of the rectifier bridge or the output terminal of the rectifier bridge, and the output terminal of the overvoltage protection circuit is connected to the control terminal of the lower transistor in the second bridge branch.

[0036] Alternatively, the input terminal of the rectifier bridge includes a second input terminal, which is located at the common node of the upper and lower transistors in the second bridge branch. The output terminal of the rectifier bridge is located at the common node of the upper transistor in the first and second bridge branches. The upper transistor in the second bridge branch is normally open, and the lower transistor in the second bridge branch is normally closed.

[0037] The input terminal of the overvoltage protection circuit is connected to the first input terminal of the rectifier bridge or the output terminal of the rectifier bridge, and the output terminal of the overvoltage protection circuit is connected to the control terminal of the lower transistor in the first bridge branch.

[0038] The overvoltage protection circuit includes an overvoltage detection circuit and a drive circuit;

[0039] The input terminal of the overvoltage detection circuit serves as the input terminal of the overvoltage protection circuit, and the output terminal of the overvoltage detection circuit is connected to the first terminal of the drive circuit. The overvoltage detection circuit sends a first level signal to the drive circuit when the input terminal or the output terminal of the rectifier bridge is overvoltageed.

[0040] The second terminal of the driving circuit serves as the output terminal of the overvoltage protection circuit, and the driving circuit is used to drive the lower transistor to conduct according to the first level signal.

[0041] In a fifth aspect, embodiments of the present invention provide an overvoltage protection circuit applied to a power receiver. The power receiver includes a rectifier bridge, which includes an upper-level transistor and a lower-level transistor connected in series between the output terminal and the ground terminal of the rectifier bridge. The common node of the upper-level transistor and the lower-level transistor is the input terminal of the rectifier bridge.

[0042] The input terminal of the overvoltage protection circuit is connected to the input terminal or the output terminal of the rectifier bridge, and the output terminal of the overvoltage protection circuit is connected to the control terminal of the lower-level transistor.

[0043] The overvoltage protection circuit includes an overvoltage detection circuit and a drive circuit;

[0044] The input terminal of the overvoltage detection circuit serves as the input terminal of the overvoltage protection circuit, and the output terminal of the overvoltage detection circuit is connected to the first terminal of the drive circuit. The overvoltage detection circuit sends a first level signal to the drive circuit when the input terminal or the output terminal of the rectifier bridge is overvoltageed.

[0045] The second terminal of the driving circuit serves as the output terminal of the overvoltage protection circuit, and the driving circuit is used to drive the lower transistor to conduct according to the first level signal.

[0046] In some embodiments, the overvoltage detection circuit includes a voltage regulator unit and a voltage divider unit;

[0047] The first terminal of the voltage regulator unit serves as the input terminal of the overvoltage detection circuit, and the second terminal of the voltage regulator unit is connected to the first terminal of the voltage divider unit. The voltage regulator unit is used to output a stable voltage signal when the input terminal or the output terminal of the rectifier bridge is overvoltaged.

[0048] The second terminal of the voltage divider unit is grounded, and the third terminal of the voltage divider unit is connected to the first terminal of the driving circuit. The voltage divider unit is used to divide the voltage according to the input voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal, or to divide the voltage according to the output voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal.

[0049] In some embodiments, the driving circuit includes an OR gate unit;

[0050] The power supply terminal of the OR gate unit is connected to the first DC power supply, the first input terminal of the OR gate unit is used to receive the first control signal of the rectifier bridge, the second input terminal of the OR gate unit is connected to the output terminal of the overvoltage detection circuit, and the output terminal of the OR gate unit serves as the second terminal of the drive circuit.

[0051] The OR gate unit is used to perform an OR operation on the first level signal and the first control signal, and output a second control signal to drive the lower-level transistor to conduct.

[0052] In a sixth aspect, embodiments of the present invention provide an overvoltage protection method applied to the overvoltage protection circuit described above, the method comprising:

[0053] When the input or output of the rectifier bridge exceeds a preset voltage threshold, the overvoltage detection circuit sends a first level signal to the drive circuit.

[0054] The driving circuit drives the upper transistor or the lower transistor to conduct according to the first level signal, so as to form a loop in the rectifier bridge.

[0055] In various embodiments of the present invention, each protection branch of the overvoltage protection circuit includes an overvoltage detection circuit and a driving circuit. When the input or output of the rectifier bridge is overvoltageed, the overvoltage detection circuit sends a first level signal to the driving circuit, causing the driving circuit to drive the upper or lower transistor in the rectifier bridge to conduct according to the first level signal, so as to form a loop in the rectifier bridge, release the overvoltage energy, and protect the rectifier bridge. Furthermore, the overvoltage protection circuit releases the overvoltage energy by actively turning on the MOS transistor in the rectifier bridge, which greatly improves the voltage limiting capability and saves chip size. Attached Figure Description

[0056] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0057] Figure 1 This is a schematic diagram of the structure of one of the power transmission systems provided in the embodiments of the present invention;

[0058] Figure 2a This is a schematic diagram of one type of overvoltage protection circuit provided in an embodiment of the present invention;

[0059] Figure 2b This is a schematic diagram of one type of overvoltage protection circuit provided in an embodiment of the present invention;

[0060] Figure 2cThis is a schematic diagram of one type of overvoltage protection circuit provided in an embodiment of the present invention;

[0061] Figure 2d This is a schematic diagram of one type of overvoltage protection circuit provided in an embodiment of the present invention;

[0062] Figure 3 This is a schematic diagram of the structure of one of the protection branches provided in an embodiment of the present invention;

[0063] Figure 4 This is a schematic diagram of the structure of one of the protection branches provided in an embodiment of the present invention;

[0064] Figure 5 This is a schematic diagram of the circuit structure of one of the protection branches provided in an embodiment of the present invention;

[0065] Figure 6 This is a schematic diagram of one type of overvoltage protection circuit provided in an embodiment of the present invention;

[0066] Figure 7 This is a schematic diagram of an overvoltage protection method provided in an embodiment of the present invention. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0068] Please see Figure 1 , Figure 1 This is a schematic diagram of a power transmission system provided in an embodiment of the present invention. The wireless power transmission system 100 includes a power converter 1 and a wireless power transmission device 2 cascaded between an input power source 200 and a load 300. In some embodiments, the power converter 1 is used to further improve the performance of the wireless power transmission system 100. In other embodiments, the power converter 1 is an optional component. In other words, the wireless power transmission device 2 can be directly connected to the input power source 200.

[0069] The wireless power transmission device 2 includes a power transmitter 3 and a power receiver 4. For example... Figure 1 As shown, the power transmitter 3 includes a cascaded transmitter circuit 31 and a transmitter coil L1. The input terminal of the transmitter circuit 31 is coupled to the output terminal of the power converter 1. The power receiver 4 includes a cascaded receiver coil L2, a resonant capacitor Cs, a rectifier circuit 41, and a power converter 42. Figure 1As shown, the resonant capacitor Cs is connected in series with the receiver coil L2 and further connected to the input terminal of the rectifier circuit 41. The output terminal of the rectifier circuit 41 is connected to the input terminal of the power converter 42. The output terminal of the power converter 42 is coupled to the load 300.

[0070] When the power receiver 4 is placed near the power transmitter 3, the power transmitter 3 is magnetically coupled to the power receiver 4 via a magnetic field. A loosely coupled transformer 115 is formed by the transmitter coil L1, which is part of the power transmitter 3, and the receiver coil L2, which is part of the power receiver 4. Therefore, electrical power can be transferred from the power transmitter 3 to the power receiver 4.

[0071] In some embodiments, the power transmitter 3 may be located within a charging pad. A transmitter coil L1 is positioned below the upper surface of the charging pad. A power receiver 4 may be embedded within a mobile phone. When the mobile phone is placed near the charging pad, magnetic coupling can be established between the transmitter coil L1 and the receiver coil L2. In other words, the transmitter coil L1 and the receiver coil L2 can form a loosely coupled transformer through which power is transferred between the power transmitter 3 and the power receiver 4. The strength of the coupling between the transmitter coil L1 and the receiver coil L2 can be quantified by a coupling coefficient k. In some embodiments, k is in the range of about 0.05 to about 0.9.

[0072] In some embodiments, after establishing magnetic coupling between transmitter coil L1 and receiver coil L2, power transmitter 3 and power receiver 4 can form a power system through which power is wirelessly transmitted from input power source 200 to load 300.

[0073] Input power source 200 may be a power adapter for converting public line voltage to direct current (DC) voltage. In other embodiments, input power source 200 may be a renewable power source such as a solar panel array. Furthermore, input power source 200 may be any suitable energy storage device, such as a rechargeable battery, a fuel cell, any combination thereof, and / or similar devices.

[0074] Load 300 represents the power consumed by a mobile device (e.g., a mobile phone) coupled to power receiver 4. In other embodiments, load 300 may refer to one or more rechargeable batteries connected in series / parallel and coupled to the output of power receiver 4. Furthermore, load 300 may be a downstream power converter, such as a battery charger.

[0075] According to some embodiments, transmitter circuit 31 may include the primary-side switch of a full-bridge converter. In other embodiments, transmitter circuit 31 may include the primary-side switch of any other suitable power converter, such as a half-bridge converter, a push-pull converter, any combination thereof, and / or similar devices.

[0076] It should be noted that the power converter described above is merely an example. Those skilled in the art will recognize that, depending on design requirements and different applications, other suitable power converters, such as those based on Class E topology (e.g., Class E amplifiers), may be used alternatively.

[0077] The transmitter circuit 31 may also include a resonant capacitor (not shown). The resonant capacitor and the magneto-inductance of the transmitter coil can form a resonant circuit. Depending on design requirements and different applications, the resonant circuit may also include a resonant inductor. In some embodiments, the resonant inductor may be implemented as an external inductor. In alternative embodiments, the resonant inductor may be implemented as a connecting wire.

[0078] The power receiver 4 includes a receiver coil L2, which is magnetically coupled to the transmitter coil L1 after the power receiver 4 is placed near the power transmitter 3. Therefore, power can be transferred to the receiver coil and further delivered to the load 300 via the rectifier circuit 41. The power receiver 4 may include, for example,... Figure 1 The secondary resonant capacitor Cs is shown. Throughout this description, the secondary resonant capacitor Cs may alternatively be referred to as the receiver resonant capacitor.

[0079] The rectifier circuit 41 converts the alternating polarity waveform received from the resonant circuit, which includes the receiver coil L2 and the receiver resonant capacitor Cs, into a unipolar waveform. In some embodiments, the rectifier circuit 41 includes a rectifier bridge formed by switching elements such as n-type metal-oxide-semiconductor (NMOS) transistors and an output capacitor.

[0080] Furthermore, the rectifier circuit 41 can be formed from other types of controllable devices, such as metal-oxide-semiconductor field-effect transistors (MOSFETs), bipolar junction transistors (BJTs), superjunction transistors (SJTs), insulated-gate bipolar transistors (IGBTs), gallium nitride (GaN)-based power devices, and / or similar devices. The detailed operation and structure of the rectifier circuit 41 are well known in the art and will not be discussed further here.

[0081] Power converter 42 is coupled between rectifier circuit 41 and load 300. Power converter 42 is a non-isolated power converter. In some embodiments, power converter 42 is implemented as a buck power converter, such as a buck-based power converter. In an alternative embodiment, power converter 42 is implemented as a four-switch buck-boost power converter.

[0082] Depending on design requirements and different applications, power converter 42 can operate in different operating modes. More specifically, power converter 42 can operate in buck mode when the load current is less than a predetermined current threshold and / or the input voltage is less than a predetermined voltage threshold. In buck mode, power converter 42 is configured as a buck power converter based on a buck circuit. When the input voltage is greater than a predetermined voltage threshold and / or the load current is greater than a predetermined current threshold, power converter 42 can operate in charge pump mode or hybrid mode. More specifically, in some embodiments, power converter 42 can operate in charge pump mode or hybrid mode when the ratio of the output voltage of power converter 42 to the input voltage of power converter 42 is less than 0.5. In charge pump mode, power converter 42 is configured as a charge pump converter. In hybrid mode, power converter 42 is configured as a power converter.

[0083] In some embodiments, the power converter 42 includes a first switch, a capacitor, and a second switch connected in series between the output of the rectifier circuit 41 and the input of the load 300. The power converter 42 also includes a third switch and a fourth switch. The third switch is connected between the common node of the first switch and the capacitor and the common node of the second switch and the output terminal of the power converter 42. The fourth switch is connected between the common node of the capacitor and the second switch and ground.

[0084] Furthermore, the power converter 42 may include a cascaded first power stage and a second power stage. The first power stage is configured to operate in different modes to effectively charge the load 300 (e.g., a rechargeable battery). In some embodiments, the first power stage may be implemented as a buck power converter (e.g., a buck-based buck power converter), a four-switch buck-boost converter, the power converter 42, and any combination thereof. The second power stage is configured as a voltage divider or an isolating switch.

[0085] Figure 2a Various embodiments according to the present invention are shown in Figure 1 The diagram shows the structure of the rectifier circuit. The rectifier circuit 41 includes a rectifier bridge, which comprises a first bridge branch 411 and a second bridge branch 412. Figure 2aTaking MOSFETs as an example, the first bridge branch 411 includes MOSFETs Q1 and Q2, and the second bridge branch 412 includes MOSFETs Q3 and Q4. MOSFETs Q1 and Q3 are the upper-level transistors, and MOSFETs Q2 and Q4 are the lower-level transistors.

[0086] Specifically, the rectifier bridge has a first input terminal and a second input terminal. The first input terminal is at the common node AC1 of MOSFETs Q1 and Q2, and the second input terminal is at the common node AC2 of MOSFETs Q3 and Q4. The rectifier bridge has one output terminal, which is at node VRECT.

[0087] The rectifier bridge can operate in full-bridge rectification mode or half-bridge rectification mode. When MOSFETs Q1-Q4 are alternately turned on, the rectifier bridge operates in full-bridge rectification mode. When MOSFETs Q1 and Q2 are alternately turned on, MOSFET Q3 is normally open (off) and MOSFET Q4 is normally closed (on), the rectifier bridge operates in half-bridge rectification mode. Alternatively, when MOSFETs Q3 and Q4 are alternately turned on, MOSFET Q1 is normally open and MOSFET Q2 is normally closed, the rectifier bridge also operates in half-bridge rectification mode.

[0088] To protect the power transistors in the rectifier bridge, the voltage at the VRECT node is typically limited. Traditionally, this can be achieved by adding a dummy load and a snubber resistor. The dummy load, located inside the chip, dissipates energy at the VRECT node when it's conducting, thus reducing the voltage. The snubber resistor, located outside the chip, reduces the VRECT voltage by turning on the internal MOS switch. However, both the dummy load and the snubber resistor are finite resistors with limited power dissipation, thus limiting their effectiveness at the VRECT node. Furthermore, they increase chip size and complicate PCB layout.

[0089] For the reasons mentioned above, embodiments of the present invention provide an overvoltage protection circuit, such as... Figure 2a As shown, the overvoltage protection circuit 43 is connected between the input terminal of the rectifier circuit 41 and the control terminal of the lower-level transistor. In other embodiments, such as... Figure 2b As shown, the overvoltage protection circuit 43 is connected between the input terminal of the rectifier circuit 41 and the control terminal of the upper transistor. In other embodiments, such as... Figure 2c As shown, the overvoltage protection circuit 43 is connected between the output terminal of the rectifier circuit 41 and the control terminal of the lower transistor. In other embodiments, such as... Figure 2d As shown, the overvoltage protection circuit 43 is connected between the output terminal of the rectifier circuit 41 and the control terminal of the upper transistor.

[0090] If the voltage at node VRECT is overvoltage, then the voltages at nodes AC1 and AC2 will also be overvoltage. Therefore, by detecting the voltages at nodes AC1 and AC2, the voltages at nodes AC1 and AC2 can be limited to limit the voltage at node VRECT, thereby protecting the rectifier bridge.

[0091] The overvoltage protection circuit 43 includes a first protection branch 431 and a second protection branch 432. The input terminal of the first protection branch 431 is connected to node AC1, and the input terminal of the second protection branch 432 is connected to node AC2. Alternatively, the input terminals of both the first protection branch 431 and the second protection branch 432 are connected to node VRECT.

[0092] The output terminal of the first protection branch 431 is connected to the control terminal of MOSFET Q1 in the first bridge branch 411, and the output terminal of the second protection branch 432 is connected to the control terminal of MOSFET Q3 in the second bridge branch 412. Alternatively, the output terminal of the first protection branch 431 is connected to the control terminal of MOSFET Q2 in the first bridge branch 411, and the output terminal of the second protection branch 432 is connected to the control terminal of MOSFET Q4 in the second bridge branch 412.

[0093] If the first protection branch 431 is connected between the first input terminal of the rectifier bridge and the control terminal of the upper-level transistor or the control terminal of the lower-level transistor, and the second protection branch 432 is connected between the second input terminal of the rectifier bridge and the control terminal of the upper-level transistor or the control terminal of the lower-level transistor, then when the voltage at node AC1 or node AC2 exceeds the preset voltage threshold, the first protection branch 431 or the second protection branch 432 can drive the corresponding upper-level transistor or lower-level transistor to conduct, so as to form a loop in the rectifier bridge and thus protect the rectifier bridge.

[0094] If both the first protection branch 431 and the second protection branch 432 are connected between the output terminal of the rectifier bridge and the control terminal of the upper-level transistor or the control terminal of the lower-level transistor, then when the voltage at node VRECT exceeds the preset voltage threshold, the first protection branch 431 and the second protection branch 432 can respectively drive the corresponding upper-level transistor or lower-level transistor to conduct, so as to form a loop in the rectifier bridge and thus protect the rectifier bridge.

[0095] If the rectifier bridge operates in half-bridge rectification mode, with MOSFET Q1 in the first bridge branch 411 in a normally open state and MOSFET Q2 in the first bridge branch 411 in a normally closed state, then the first protection branch 431 can be omitted. The input terminal of the second protection branch 432 is connected to the second input terminal of the rectifier bridge or the output terminal of the rectifier bridge, and the output terminal of the second protection branch 432 is connected to the control terminal of MOSFET Q4 in the second bridge branch 412.

[0096] If the rectifier bridge operates in half-bridge rectification mode, with MOSFET Q3 in the second bridge branch 412 in a normally open state and MOSFET Q4 in the second bridge branch in a normally closed state, the second protection branch 432 can be omitted. The input terminal of the first protection branch 431 is connected to the first input terminal or the output terminal of the rectifier bridge, and the output terminal of the first protection branch 431 is connected to the control terminal of MOSFET Q2 in the first bridge branch 411.

[0097] The other connection methods in each protection branch are the same as those in the above embodiments, and will not be described again here.

[0098] The first protection branch 431 and the second protection branch 432 have the same circuit composition and structure. The following embodiment will be described using one of the protection branches as an example.

[0099] Please see Figure 3 , Figure 3 This is a schematic diagram of a protective branch provided in an embodiment of the present invention, such as... Figure 3 As shown, each protection branch 433 includes an overvoltage detection circuit 4331 and a drive circuit 4332. The input terminal of the overvoltage detection circuit 4331 serves as the input terminal of each protection branch 433. The output terminal of the overvoltage detection circuit 4331 is connected to the first terminal of the drive circuit 4332, and the second terminal of the drive circuit 4332 serves as the output terminal of each protection branch 433.

[0100] Taking the output terminal of each protection branch 433 connected to the control terminal of MOSFET Q2 and the control terminal of MOSFET Q4 respectively as an example, if one of the overvoltage detection circuits 4331 is connected between node AC1 and the control terminal of MOSFET Q2, when the voltage at node AC1 exceeds the preset voltage threshold, the overvoltage detection circuit 4331 outputs a first level signal to the drive circuit 4332. The drive circuit 4332 drives MOSFET Q2 to conduct according to the first level signal, so that node AC1, MOSFET Q2, the body diode of MOSFET Q4 and node AC2 form a first loop, releasing the overvoltage energy and limiting the voltage at VRECT to protect the rectifier bridge.

[0101] Another overvoltage detection circuit 4331 is connected between node AC2 and the control terminal of MOSFET Q4. When the voltage at node AC2 exceeds the preset voltage threshold, the overvoltage detection circuit 4331 outputs a first level signal to the drive circuit 4332. The drive circuit 4332 drives MOSFET Q4 to conduct according to the first level signal, so that node AC2, MOSFET Q4, the body diode of MOSFET Q2 and node AC1 form a second loop, releasing the overvoltage energy and limiting the voltage at VRECT to protect the rectifier bridge.

[0102] In overvoltage protection mode, rectifier circuit 41 operates in a non-rectifying state and has no rectified output. The voltages at nodes AC1 and AC2 switch between the positive and negative overvoltage values, and rectifier circuit 41 also switches between the first and second circuits.

[0103] If one overvoltage detection circuit 4331 is connected between node VRECT and the control terminal of MOSFET Q2, and the other overvoltage detection circuit 4331 is connected between node VRECT and the control terminal of MOSFET Q4, then when the voltage at node VRECT exceeds a preset voltage threshold, the overvoltage detection circuit 4331 outputs a first level signal to the drive circuit 4332. The drive circuit 4332 drives both MOSFET Q2 and MOSFET Q4 to conduct according to the first level signal, so that node AC1, MOSFET Q2, MOSFET Q4 and node AC2 form a third loop, releasing overvoltage energy and limiting the voltage at VRECT to protect the rectifier bridge.

[0104] The output terminal of each protection branch 433 is connected to the control terminal of MOSFET Q1 and the control terminal of MOSFET Q3 respectively. The working principle is the same as that in the above embodiment, and will not be repeated here.

[0105] When the voltage at the VRECT node of the rectifier bridge is over-voltage, the overvoltage energy is discharged by actively turning on the upper or lower transistor. Compared with linearly improving the voltage limiting capability by adding virtual load and absorption resistor, this overvoltage protection circuit can improve the voltage limiting capability exponentially or by turning point, which greatly improves the voltage limiting capability and saves chip size.

[0106] In summary, each protection branch in this overvoltage protection circuit includes an overvoltage detection circuit and a driving circuit. When an overvoltage occurs at the input or output of the rectifier bridge, the overvoltage detection circuit sends a first-level signal to the driving circuit, causing the driving circuit to turn on the upper or lower transistor in the rectifier bridge according to the first-level signal, thereby forming a loop in the rectifier bridge, releasing the overvoltage energy, and protecting the rectifier bridge. Furthermore, this overvoltage protection circuit releases overvoltage energy by actively turning on the MOS transistor in the rectifier bridge, which greatly improves the voltage limiting capability and saves chip size.

[0107] Please see Figure 4 , Figure 4 This is a schematic diagram of an overvoltage protection circuit provided in an embodiment of the present invention, as shown below. Figure 4As shown, the overvoltage detection circuit 4331 includes a voltage regulator unit 43311 and a voltage divider unit 43312. The first terminal of the voltage regulator unit 43311 serves as the input terminal of the overvoltage detection circuit 4331, and the second terminal of the voltage regulator unit 43311 is connected to the first terminal of the voltage divider unit 43312. The second terminal of the voltage divider unit 43312 is grounded, and the third terminal of the voltage divider unit 43312 is connected to the first terminal of the drive circuit 4332.

[0108] When the input terminal of the rectifier bridge is overvoltage, the voltage regulator unit 43311 outputs a stable voltage signal to provide a regulated value, and the voltage divider unit 43312 divides the difference between the input voltage signal of the rectifier bridge and the regulated value to provide a divided voltage signal as the first level signal.

[0109] When the output of the rectifier bridge is over-voltage, the voltage regulator unit 43311 outputs a stable voltage signal to provide a regulated value. The voltage divider unit 43312 divides the difference between the output voltage signal of the rectifier bridge and the regulated value to provide a divided voltage signal as the first level signal.

[0110] In some embodiments, the driving circuit 4332 includes an OR gate unit 43321. The power supply terminal of the OR gate unit 43321 is connected to the first DC power supply 400. The first input terminal of the OR gate unit 43321 is used to receive the first control signal of the rectifier bridge. The second input terminal of the OR gate unit 43321 is connected to the output terminal of the overvoltage detection circuit 4331. The output terminal of the OR gate unit 43321 serves as the second terminal of the driving circuit 4332.

[0111] The first control signal is the control signal when the rectifier bridge is working normally. When the second input terminal of the OR gate unit 43321 receives the first level signal, the OR gate unit 43321 performs an OR operation on the first level signal and the first control signal, and outputs the second control signal to drive the upper or lower transistor to conduct.

[0112] In some embodiments, the driving circuit 4332 further includes a first unidirectional conduction unit 43322, wherein a first end of the first unidirectional conduction unit 43322 is connected to the first DC power supply 400, and a second end of the first unidirectional conduction unit 43322 is connected to the power supply terminal of the OR gate unit 43321.

[0113] The first DC power supply 400 can be applied to the power supply terminal of the OR gate unit 43321 via the first unidirectional conduction unit 43322, enabling the OR gate unit 43321 to operate normally. At the same time, the first unidirectional conduction unit 43322 can prevent the control terminal voltage of the upper transistor or the control terminal voltage of the lower transistor from leaking to the first DC power supply 400, thus protecting it.

[0114] The first DC power supply 400 is an externally controlled power supply, which can be set as needed. In this embodiment of the invention, the voltage of the first DC power supply 400 is 5V.

[0115] In some embodiments, the first DC power supply 400 may experience a power outage, or when the entire system just starts working, the rectifier bridge input is already powered, but the first DC power supply 400 has not yet been established. At this time, the OR gate unit 43321 is in a de-energized state and cannot work normally, and cannot provide overvoltage protection for the rectifier bridge.

[0116] For the reasons mentioned above, the driving circuit 4332 further includes a second unidirectional conduction unit 43323, wherein the first end of the second unidirectional conduction unit 43323 is connected to the output end of the overvoltage detection circuit 4331, and the second end of the second unidirectional conduction unit 43323 serves as the second end of the driving circuit 4332.

[0117] When the overvoltage detection circuit 4331 outputs a first-level signal, the second unidirectional conduction unit 43323 outputs a conduction signal to drive the upper-level transistor or the lower-level transistor to conduct. Simultaneously, the second unidirectional conduction unit 43323 can also prevent the control terminal voltage of the upper-level transistor or the lower-level transistor from leaking to the overvoltage detection circuit 4331.

[0118] In summary, this overvoltage protection circuit releases overvoltage energy by actively turning on the MOSFETs in the rectifier bridge, thus providing overvoltage protection for the rectifier bridge. It also significantly improves voltage limiting capability and saves chip size.

[0119] The following description uses one of the protection branches, 433, as an example to illustrate the specific circuit composition and working principle of the protection branch 433.

[0120] Please see Figure 5 , Figure 5 This is a schematic diagram of a protection branch circuit provided by an embodiment of the present invention. The voltage regulation unit 43311 includes a plurality of Zener diodes. The number of Zener diodes is determined according to the voltage rating of the power transistors in the rectifier bridge. In one embodiment, the voltage regulation value of a single Zener diode is 5.5V. In this embodiment, as... Figure 5As shown, the connection method and working principle of the voltage regulator unit 43311, which includes two Zener diodes, are described as an example. Specifically, the voltage regulator unit 43311 includes a first Zener diode D1 and a second Zener diode D2, and the voltage divider unit 43312 includes a first resistor R1. The cathode of the first Zener diode D1 serves as the first terminal of the voltage regulator unit 43311, used to connect to node AC1, node AC2, or node VRECT. The anode of the first Zener diode D1 is connected to the cathode of the second Zener diode D2. The anode of the second Zener diode D2 is connected to one end of the first resistor R1 and the first terminal of the drive circuit 4332, respectively. The other end of the first resistor R1 is grounded.

[0121] OR gate unit 43321 includes a first OR gate OR1, and the first unidirectional conduction unit 43322 includes a first diode. The first input terminal of the first OR gate OR1 is used to receive the first control signal of the rectifier bridge, and the second input terminal of the first OR gate OR1 is connected to the output terminal of the overvoltage detection circuit 4331. Specifically, the second input terminal of the first OR gate OR1 is connected to the anode of the second Zener diode D2, and the output terminal of the first OR gate OR1 serves as the second terminal of the drive circuit 4332, used to connect to the control terminal of the corresponding upper-level transistor or the control terminal of the lower-level transistor (lower-level transistor Q2 or Q4 is shown in the figure).

[0122] The power supply terminal of the first OR gate OR1 is connected to the cathode of the first diode D3, and the anode of the first diode D3 is used to connect to the first DC power supply VDD.

[0123] The second unidirectional conduction unit 43323 includes a second diode D4. The anode of the second diode D4 is connected to the output terminal of the overvoltage detection circuit 4331. Specifically, the anode of the second diode D4 is connected to the anode of the second Zener diode D2. The cathode of the second diode D4 serves as the second terminal of the drive circuit 4332, which is used to connect to the control terminal of the corresponding upper-level transistor or the control terminal of the lower-level transistor (lower-level transistor Q2 or Q4 is shown in the figure).

[0124] Combination Figure 5 The working principle of the protection branch 433 can be described as follows:

[0125] When the voltage at node AC1 exceeds the preset voltage threshold, the first Zener diode D1 and the second Zener diode D2 are reverse-broken down, and they output a stable voltage signal. The voltage value of the stable voltage signal is the sum of the first regulated voltage value and the second regulated voltage value. The first resistor R1 divides the voltage at node AC1 and the voltage of the stable voltage signal, and outputs the first level signal AC_OV. The voltage of the first level signal AC_OV is the voltage at node AC1 minus the first regulated voltage value and the second regulated voltage value.

[0126] The first level signal AC_OV is a high level signal. The first level signal AC_OV acts on the second input terminal of the first OR gate OR1. The first OR gate OR1 performs an OR operation on the first control signal Normal Control and the first level signal AC_OV. The first OR gate OR1 outputs a high level second control signal. The second control signal acts on the control terminal of MOSFET Q1 or MOSFET Q2, driving MOSFET Q1 or MOSFET Q2 to turn on.

[0127] If the first DC power supply VDD is de-energized or not powered on, the first OR gate OR1 will not function properly. The first level signal AC_OV can also be applied to the control terminal of MOSFET Q1 or MOSFET Q2 via the second diode D4, driving MOSFET Q1 or MOSFET Q2 to conduct.

[0128] If the voltage at node AC2 exceeds the voltage threshold, the drive circuit 4332 drives MOSFET Q3 or MOSFET Q4 to conduct. The working principle of the overvoltage detection circuit 4331 and the drive circuit 4332 is the same as in the above embodiment, and will not be repeated here.

[0129] If the voltage at node VRECT exceeds the voltage threshold, the driving circuit 4332 drives MOSFETs Q1 and Q3 to conduct or drives MOSFETs Q2 and Q4 to conduct. The working principle of the overvoltage detection circuit 4331 and the driving circuit 4332 is the same as in the above embodiment, and will not be repeated here.

[0130] If the rectifier bridge operates in half-bridge mode, and MOSFET Q3 is normally open and MOSFET Q4 is normally closed, then when the voltage at node AC1 exceeds the voltage threshold or the voltage at node VRECT exceeds the voltage threshold, the driver circuit 4332 drives MOSFET Q2 to conduct. If MOSFET Q1 is normally open and MOSFET Q2 is normally closed, then when the voltage at node AC2 exceeds the voltage threshold or the voltage at node VRECT exceeds the voltage threshold, the driver circuit 4332 drives MOSFET Q4 to conduct.

[0131] In some embodiments, such as Figure 6 As shown, the rectifier bridge is in half-bridge mode, and the rectifier bridge includes a master MOSFET Q connected in series between the output terminal and the ground terminal of the rectifier bridge. A and the lower-level MOSFET Q B upper-level MOSFET Q A With the lower-level MOSFET Q B The common node is the input terminal of the rectifier bridge. The input terminal of the overvoltage protection circuit is connected to either the input terminal or the output terminal of the rectifier bridge (not shown in the figure). The output terminal of the overvoltage protection circuit is connected to the lower-level MOSFET Q. B The control terminal.

[0132] The overvoltage protection circuit 433 includes an overvoltage detection circuit 4331 and a drive circuit 4332. The input terminal of the overvoltage detection circuit 4331 serves as the input terminal of the overvoltage protection circuit 433, the output terminal of the overvoltage detection circuit 4331 is connected to the first terminal of the drive circuit 4332, and the second terminal of the drive circuit 4332 serves as the output terminal of the overvoltage protection circuit 433.

[0133] When an overvoltage occurs at the input or output of the rectifier bridge, the overvoltage detection circuit 4331 sends a first-level signal to the drive circuit 4332, causing the drive circuit 4332 to drive the lower-level MOSFET Q according to the first-level signal. B The circuit is turned on. The input terminal of the rectifier bridge is at node AC, and the output terminal of the rectifier bridge is at node VRECT. That is, when the voltage at node AC exceeds the voltage threshold or the voltage at node VRECT exceeds the voltage threshold, the driving circuit 4332 drives the MOSFET Q. B Conduction.

[0134] In summary, this overvoltage protection circuit releases overvoltage energy by actively turning on the MOSFETs in the rectifier bridge, thus providing overvoltage protection for the rectifier bridge. It also significantly improves voltage limiting capability and saves chip size.

[0135] Please see Figure 7 This invention provides an overvoltage protection method applied to the aforementioned overvoltage protection circuit, such as... Figure 7 As shown, the overvoltage protection method S700 includes:

[0136] S71. When the input terminal or the output terminal of the rectifier bridge exceeds a preset voltage threshold, the overvoltage detection circuit sends a first level signal to the drive circuit.

[0137] S72. The driving circuit drives the upper transistor or the lower transistor to conduct according to the first level signal, so as to form a loop in the rectifier bridge.

[0138] In some embodiments, step S72 includes:

[0139] The driving circuit drives the upper transistor in the first bridge branch to conduct according to the first level signal, so that the first input terminal of the rectifier bridge, the upper transistor in the first bridge branch, the body diode of the upper transistor in the second bridge branch, and the second input terminal of the rectifier bridge form a first circuit; or...

[0140] The driving circuit drives the upper transistor in the second bridge branch to conduct according to the first level signal, so that the second input terminal of the rectifier bridge, the upper transistor in the second bridge branch, the body diode of the upper transistor in the first bridge branch, and the first input terminal of the rectifier bridge form a second circuit; or...

[0141] The driving circuit drives the upper transistors in the first bridge branch and the second bridge branch to conduct according to the first level signal, so that the first input terminal of the rectifier bridge, the upper transistors in the first bridge branch, the upper transistors in the second bridge branch, and the second input terminal of the rectifier bridge form a third circuit.

[0142] In some embodiments, step S72 further includes:

[0143] The driving circuit drives the upper transistor in the first bridge branch to conduct according to the first level signal, so that the first input terminal of the rectifier bridge, the upper transistor in the first bridge branch, the body diode of the upper transistor in the second bridge branch, and the second input terminal of the rectifier bridge form a first circuit; or...

[0144] The driving circuit drives the upper transistor in the second bridge branch to conduct according to the first level signal, so that the second input terminal of the rectifier bridge, the upper transistor in the second bridge branch, the body diode of the upper transistor in the first bridge branch, and the first input terminal of the rectifier bridge form a second circuit; or...

[0145] The driving circuit drives the upper transistors in the first bridge branch and the second bridge branch to conduct according to the first level signal, so that the first input terminal of the rectifier bridge, the upper transistors in the first bridge branch, the upper transistors in the second bridge branch, and the second input terminal of the rectifier bridge form a third circuit.

[0146] In some embodiments, step S72 further includes:

[0147] The driving circuit drives the lower-level transistor to conduct according to the first level signal, so that the input terminal of the rectifier bridge, the lower-level transistor, and the ground terminal of the rectifier bridge form a fourth circuit.

[0148] It should be noted that since the overvoltage protection method S700 described above is based on the same inventive concept as the overvoltage protection circuit in the above embodiment, the corresponding content of the overvoltage protection circuit described above is also applicable to the embodiment of the overvoltage protection method S700, and will not be described in detail here.

[0149] In summary, this overvoltage protection method releases overvoltage energy by actively turning on the MOSFETs in the rectifier bridge, thus providing overvoltage protection for the rectifier bridge and significantly improving its voltage limiting capability.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An overvoltage protection circuit, applied to a power receiver, characterized in that, The power receiver includes a rectifier bridge, which includes a first bridge branch and a second bridge branch. The rectifier bridge includes a first input terminal and a second input terminal. The first input terminal of the rectifier bridge is located at the common node of the upper-level transistor and the lower-level transistor in the first bridge branch. The second input terminal of the rectifier bridge is located at the common node of the upper-level transistor in the first bridge branch and the upper-level transistor in the second bridge branch. The overvoltage protection circuit includes a first protection branch and a second protection branch. The input terminal of the first protection branch is connected to the first input terminal of the rectifier bridge, and the input terminal of the second protection branch is connected to the second input terminal of the rectifier bridge; or, the input terminals of both the first protection branch and the second protection branch are connected to the output terminal of the rectifier bridge. The output terminal of the first protection branch is connected to the control terminal of the upper-level tube in the first bridge branch, and the output terminal of the second protection branch is connected to the control terminal of the upper-level tube in the second bridge branch; or, the output terminal of the first protection branch is connected to the control terminal of the lower-level tube in the first bridge branch, and the output terminal of the second protection branch is connected to the control terminal of the lower-level tube in the second bridge branch. Each protection branch includes an overvoltage detection circuit and a drive circuit; The input terminal of the overvoltage detection circuit serves as the input terminal of each protection branch, and the output terminal of the overvoltage detection circuit is connected to the first terminal of the drive circuit. When the input terminal or the output terminal of the rectifier bridge is overvoltageed, the overvoltage detection circuit sends a first level signal to the drive circuit. The second end of the driving circuit serves as the output end of each protection branch, and the driving circuit is used to drive the upper transistor or the lower transistor to conduct according to the first level signal. The driving circuit includes an OR gate unit; The power supply terminal of the OR gate unit is connected to the first DC power supply, the first input terminal of the OR gate unit is used to receive the first control signal of the rectifier bridge, the second input terminal of the OR gate unit is connected to the output terminal of the overvoltage detection circuit, and the output terminal of the OR gate unit serves as the second terminal of the drive circuit. The OR gate unit is used to perform an OR operation on the first level signal and the first control signal, and output a second control signal to drive the upper-level transistor or the lower-level transistor to conduct.

2. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage detection circuit includes a voltage regulator unit and a voltage divider unit; The first terminal of the voltage regulator unit serves as the input terminal of the overvoltage detection circuit, and the second terminal of the voltage regulator unit is connected to the first terminal of the voltage divider unit. The voltage regulator unit is used to output a stable voltage signal when the input terminal or the output terminal of the rectifier bridge is overvoltaged. The second terminal of the voltage divider unit is grounded, and the third terminal of the voltage divider unit is connected to the first terminal of the driving circuit. The voltage divider unit is used to divide the voltage according to the input voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal, or to divide the voltage according to the output voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal.

3. The overvoltage protection circuit according to claim 2, characterized in that, The voltage regulator unit includes a plurality of Zener diodes connected in series, and the voltage divider unit includes a first resistor; The cathode of the first Zener diode among the plurality of Zener diodes serves as the first terminal of the voltage regulation unit. The anode of the last Zener diode among the plurality of Zener diodes is connected to one end of the first resistor and the first terminal of the driving circuit, respectively. The other end of the first resistor is grounded.

4. The overvoltage protection circuit according to claim 1, characterized in that, The driving circuit also includes a first unidirectional conduction unit; The first terminal of the first unidirectional conduction unit is connected to the first DC power supply, and the second terminal of the first unidirectional conduction unit is connected to the power supply terminal of the OR gate unit. The first unidirectional conduction unit is used to prevent the control terminal voltage of the upper transistor or the control terminal voltage of the lower transistor from leaking to the first DC power supply.

5. The overvoltage protection circuit according to claim 4, characterized in that, The OR gate unit includes a first OR gate, and the first unidirectional conduction unit includes a first diode; The power supply terminal of the first OR gate is connected to the cathode of the first diode, and the anode of the first diode is used to connect to the first DC power supply. The first input terminal of the first OR gate is used to receive the first control signal of the rectifier bridge, the second input terminal of the first OR gate is connected to the output terminal of the overvoltage detection circuit, and the output terminal of the first OR gate serves as the second terminal of the drive circuit.

6. The overvoltage protection circuit according to any one of claims 1-5, characterized in that, The driving circuit also includes a second unidirectional conduction unit; The first end of the second unidirectional conduction unit is connected to the output end of the overvoltage detection circuit, and the second end of the second unidirectional conduction unit serves as the second end of the driving circuit. The second unidirectional conduction unit is used to output a conduction signal according to the first level signal to drive the upper transistor or the lower transistor to conduct.

7. The overvoltage protection circuit according to claim 6, characterized in that, The second unidirectional conduction unit includes a second diode; The anode of the second diode is connected to the output terminal of the overvoltage detection circuit, and the cathode of the second diode serves as the second terminal of the driving circuit.

8. A power receiver, characterized in that, include: A receiving coil, used for coupling to a transmitting coil; The rectifier bridge is connected to the receiving coil; as well as, The overvoltage protection circuit as described in any one of claims 1-7 is used to drive the upper or lower transistor of the rectifier bridge to conduct when the rectifier bridge is overvoltaged.

9. A wireless power transmission device, characterized in that, The device includes a power transmitter and a power receiver as described in claim 8, wherein the power transmitter includes a transmitting coil for coupling electrical energy to the receiving coil via the transmitting coil.

10. An overvoltage protection circuit, applied to a power receiver, characterized in that, The power receiver includes a rectifier bridge, which includes a first bridge branch and a second bridge branch. The input terminal of the rectifier bridge includes a first input terminal, which is located at the common node of the upper-level transistor and the lower-level transistor in the first bridge branch. The output terminal of the rectifier bridge is located at the common node of the upper-level transistor in the first bridge branch and the upper-level transistor in the second bridge branch. The upper-level transistor in the first bridge branch is normally open, and the lower-level transistor in the first bridge branch is normally closed. The input terminal of the overvoltage protection circuit is connected to the second input terminal of the rectifier bridge or the output terminal of the rectifier bridge, and the output terminal of the overvoltage protection circuit is connected to the control terminal of the lower transistor in the second bridge branch. Alternatively, the input terminal of the rectifier bridge includes a second input terminal, which is located at the common node of the upper and lower transistors in the second bridge branch. The output terminal of the rectifier bridge is located at the common node of the upper transistor in the first and second bridge branches. The upper transistor in the second bridge branch is normally open, and the lower transistor in the second bridge branch is normally closed. The input terminal of the overvoltage protection circuit is connected to the first input terminal of the rectifier bridge or the output terminal of the rectifier bridge, and the output terminal of the overvoltage protection circuit is connected to the control terminal of the lower transistor in the first bridge branch. The overvoltage protection circuit includes an overvoltage detection circuit and a drive circuit; The input terminal of the overvoltage detection circuit serves as the input terminal of the overvoltage protection circuit, and the output terminal of the overvoltage detection circuit is connected to the first terminal of the drive circuit. The overvoltage detection circuit sends a first level signal to the drive circuit when the input terminal or the output terminal of the rectifier bridge is overvoltageed. The second terminal of the driving circuit serves as the output terminal of the overvoltage protection circuit, and the driving circuit is used to drive the lower transistor to conduct according to the first level signal. The driving circuit includes an OR gate unit; The power supply terminal of the OR gate unit is connected to the first DC power supply, the first input terminal of the OR gate unit is used to receive the first control signal of the rectifier bridge, the second input terminal of the OR gate unit is connected to the output terminal of the overvoltage detection circuit, and the output terminal of the OR gate unit serves as the second terminal of the drive circuit. The OR gate unit is used to perform an OR operation on the first level signal and the first control signal, and output a second control signal to drive the lower-level transistor to conduct.

11. An overvoltage protection circuit, applied to a power receiver, characterized in that, The power receiver includes a rectifier bridge, which comprises an upper-level transistor and a lower-level transistor connected in series between the output terminal and the ground terminal of the rectifier bridge. The common node of the upper-level transistor and the lower-level transistor is the input terminal of the rectifier bridge. The input terminal of the overvoltage protection circuit is connected to the input terminal or the output terminal of the rectifier bridge, and the output terminal of the overvoltage protection circuit is connected to the control terminal of the lower-level transistor. The overvoltage protection circuit includes an overvoltage detection circuit and a drive circuit; The input terminal of the overvoltage detection circuit serves as the input terminal of the overvoltage protection circuit, and the output terminal of the overvoltage detection circuit is connected to the first terminal of the drive circuit. The overvoltage detection circuit sends a first level signal to the drive circuit when the input terminal or the output terminal of the rectifier bridge is overvoltageed. The second terminal of the driving circuit serves as the output terminal of the overvoltage protection circuit, and the driving circuit is used to drive the lower transistor to conduct according to the first level signal. The driving circuit includes an OR gate unit; The power supply terminal of the OR gate unit is connected to the first DC power supply, the first input terminal of the OR gate unit is used to receive the first control signal of the rectifier bridge, the second input terminal of the OR gate unit is connected to the output terminal of the overvoltage detection circuit, and the output terminal of the OR gate unit serves as the second terminal of the drive circuit. The OR gate unit is used to perform an OR operation on the first level signal and the first control signal, and output a second control signal to drive the lower-level transistor to conduct.

12. The overvoltage protection circuit according to claim 10 or 11, characterized in that, The overvoltage detection circuit includes a voltage regulator unit and a voltage divider unit; The first terminal of the voltage regulator unit serves as the input terminal of the overvoltage detection circuit, and the second terminal of the voltage regulator unit is connected to the first terminal of the voltage divider unit. The voltage regulator unit is used to output a stable voltage signal when the input terminal or the output terminal of the rectifier bridge is overvoltaged. The second terminal of the voltage divider unit is grounded, and the third terminal of the voltage divider unit is connected to the first terminal of the driving circuit. The voltage divider unit is used to divide the voltage according to the input voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal, or to divide the voltage according to the output voltage signal of the rectifier bridge and the stable voltage signal to generate the first level signal.

13. An overvoltage protection method, characterized in that, Applied to an overvoltage protection circuit as described in any one of claims 1-7 or any one of claims 10-12, the method comprises: When the input or output of the rectifier bridge exceeds a preset voltage threshold, the overvoltage detection circuit sends a first level signal to the drive circuit. The driving circuit drives the upper transistor or the lower transistor to conduct according to the first level signal, so as to form a loop in the rectifier bridge.

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