Wireless charging circuit and wireless charging device

Abstract

The utility model relates to the technical field of charging, in particular to a wireless charging circuit and a wireless charging device. The wireless charging circuit comprises an alternating current input end, a transformer, a transformer control module, a voltage regulation feedback module, a main control chip and a wireless charging output module, the alternating current input end is connected with the primary end of the transformer and the transformer control module, and the secondary end of the transformer is connected with the wireless charging output module and the voltage regulation feedback module. The transformer control module is connected with a primary end of a transformer and the voltage regulation feedback module, the main control chip is connected with the voltage regulation feedback module and the wireless charging output module, the main control chip outputs a PWM signal based on a secondary voltage output by a secondary end of the transformer, and the voltage regulation feedback module outputs a feedback voltage based on the secondary voltage and the PWM signal. And the transformer control module controls and adjusts the secondary voltage output by the secondary end of the transformer based on the feedback voltage. The overall circuit size can be reduced, and the overall circuit cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of charging, in particular to a wireless charging circuit and a wireless charging device. Background Art

[0002] A wireless charger is a device that uses the principle of electromagnetic induction for charging. It is equipped with a coil at both the transmitting end and the receiving end. The transmitting-end coil emits an electromagnetic signal to the outside under the action of electricity, and the receiving-end coil receives the electromagnetic signal and converts it into an electric current, thereby achieving the purpose of wireless charging.

[0003] In the market, to achieve wireless charging of electronic devices, an external power adapter is usually adopted. The power adapter is connected to the AC power supply terminal, and the output terminal of the power adapter is connected to the input terminal of the wireless charger. The wireless charger charges an electronic device such as a mobile phone. In the wireless charger, a DC-DC conversion circuit is usually set. The DC-DC conversion circuit receives the voltage transmitted by the power adapter, and the main control chip in the wireless charger controls and adjusts the DC-DC conversion circuit to output an appropriate voltage to provide an appropriate voltage for subsequent wireless charging.

[0004] However, in the above wireless charging method, the overall circuit for realizing wireless charging has a redundant DC-DC conversion circuit, resulting in a higher circuit cost and a larger circuit volume. Summary of the Utility Model

[0005] The technical problem to be solved by the embodiments of the present utility model is to provide a wireless charging circuit and a wireless charger to solve the problems of redundant circuit structure, high circuit cost, and large circuit volume of the wireless charging circuit in the prior art.

[0006] The present utility model discloses a wireless charging circuit, including an AC input terminal, a transformer, a transformer control module, a voltage regulation feedback module, a main control chip, and a wireless charging output module. The AC input terminal is connected to the primary terminal of the transformer and the transformer control module. The secondary terminal of the transformer is connected to the wireless charging output module and the voltage regulation feedback module. The transformer control module is connected to the primary terminal of the transformer and the voltage regulation feedback module. The main control chip is connected to the voltage regulation feedback module and the wireless charging output module. Among them, the main control chip outputs a PWM signal based on the secondary voltage output by the secondary terminal of the transformer. The voltage regulation feedback module outputs a feedback voltage based on the secondary voltage and the PWM signal. The transformer control module controls and adjusts the secondary voltage output by the secondary terminal of the transformer based on the feedback voltage.

[0007] Optionally, the voltage regulation feedback module includes a voltage regulator chip and a voltage sampling unit. The reference terminal of the voltage regulator chip is connected to the voltage division node of the voltage sampling unit and the main control chip, the anode is grounded, and the cathode is connected to the transformer control module. One end of the voltage sampling unit is connected to the secondary terminal of the transformer, and the other end is grounded.

[0008] Optionally, the voltage sampling unit includes a first resistor, a second resistor, and a third resistor. The first resistor, the second resistor, and the third resistor are connected in series in sequence. The series node of the second resistor and the third resistor is connected to the main control chip, the cathode of the voltage regulator chip, and the reference terminal. The other end of the first resistor is connected to the secondary terminal of the transformer, and the other end of the third resistor is grounded.

[0009] Optionally, the wireless charging circuit further includes an optocoupler. The input terminal of the optocoupler is connected to the secondary terminal of the transformer and the cathode of the voltage regulator chip, and the output terminal of the optocoupler is connected to the transformer control module.

[0010] Optionally, the transformer control module includes a power management chip. The power management chip is connected to the output terminal of the optocoupler, the AC input terminal, and the primary terminal of the transformer. The power management chip controls and adjusts the secondary voltage of the secondary terminal of the transformer based on the feedback voltage transmitted by the optocoupler.

[0011] Optionally, the wireless charging output module includes a full-bridge drive unit and a wireless charging coil. The full-bridge drive unit is connected to the wireless charging coil, the main control chip, and the secondary terminal of the transformer.

[0012] Optionally, the wireless charging circuit further includes a sampling and demodulation circuit module. The sampling and demodulation circuit module is used to collect the modulation signal of the external charging receiving end. The sampling and demodulation circuit module is connected to the main control module and the wireless charging output module.

[0013] Optionally, the wireless charging circuit further includes a rectification and filtering module. The rectification and filtering module is used to convert the low-voltage AC voltage into a low-voltage DC voltage. The input terminal of the rectification and filtering module is connected to the secondary terminal of the transformer, and the output terminal of the rectification and filtering module is connected to the voltage regulation feedback module and the wireless charging output module.

[0014] Optionally, the wireless charging circuit includes a rectification circuit module. The rectification circuit module is used to convert the high-voltage AC voltage into a high-voltage DC voltage. The input terminal of the rectification circuit module is connected to the AC input terminal, and the output terminal of the rectification circuit module is connected to the input terminal of the transformer and the transformer control module.

[0015] The present utility model also discloses a wireless charging device, which includes a housing, a circuit board and the wireless charging circuit as described above. The wireless charging circuit is arranged on the circuit board, and the circuit board is encapsulated in the housing.

[0016] Compared with the prior art, the beneficial effects of the wireless charging circuit and the wireless charging device provided by the embodiments of the present utility model are as follows: by providing an AC input terminal, a transformer, a transformer control module, a voltage regulation feedback module, a main control chip and a wireless charging output module, the AC input terminal is connected to the primary terminal of the transformer and the transformer control module, the secondary terminal of the transformer is connected to the wireless charging output module and the voltage regulation feedback module, the transformer control module is connected to the primary terminal of the transformer and the voltage regulation feedback module, and the main control chip is connected to the voltage regulation feedback module and the wireless charging output module. By adjusting the circuit structure, the main control chip directly adjusts the feedback voltage of the voltage regulation feedback module according to the secondary voltage output by the secondary terminal of the transformer. Furthermore, the transformer control module controls and adjusts the voltage output by the secondary terminal of the transformer to supply a suitable voltage to the wireless charging output module based on the feedback voltage, optimizing the overall wireless charging circuit, saving the original DC-DC conversion circuit of the wireless charger, reducing the overall circuit volume, lowering the overall circuit cost, and since the DC-DC conversion circuit is saved, the circuit efficiency loss is reduced. Description of the Drawings

[0017] The technical solutions of the present utility model will be further described in detail below in conjunction with the drawings. In the drawings:

[0018] Figure 1 is a schematic diagram of the modules of the wireless charging circuit provided by the embodiments of the present utility model Figure 1 ;

[0019] Figure 2 is a schematic diagram of the modules of the wireless charging circuit provided by the embodiments of the present utility model Figure 2 ;

[0020] Figure 3 is a partial circuit schematic diagram of the rectifier circuit module, the transformer, the rectifier and filter module, the transformer control module and the voltage regulation feedback module provided by the embodiments of the present utility model;

[0021] Figure 4 is a partial circuit schematic diagram of the main control chip and its peripheral circuits provided by the embodiments of the present utility model;

[0022] Figure 5 is a partial circuit schematic diagram of the wireless charging output module provided by the embodiments of the present utility model;

[0023] Figure 6 is a partial circuit schematic diagram of the sampling and demodulation circuit module provided by the embodiments of the present utility model.

[0024] The reference numerals in the figures are as follows:

[0025] 10, AC input terminal; 20 (T1), transformer; 30, transformer control module; 40, voltage regulation feedback module; 41 (U1), voltage regulator chip; 42, voltage sampling unit; 50 (U2), main control chip; 60, wireless charging output module; 61, full-bridge drive unit; 62, wireless charging coil; 70, sampling and demodulation circuit module; 80, rectification and filtering module; 90, rectification circuit module;

[0026] R1, first resistor; R2, second resistor; R3, third resistor; U3, optocoupler; U4, power management chip; Q1, first MOS transistor; Q2, second MOS transistor; Q3, third MOS transistor; Q4, fourth MOS transistor; C1, filter capacitor; D1, first diode; D2, second diode; D3, third diode; D4, fourth diode; D5, fifth diode. Specific embodiments

[0027] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Now, with reference to the drawings, the preferred embodiments of the present invention will be described in detail.

[0028] An embodiment of the present invention provides a wireless charging circuit. As Figure 1 shown, the wireless charging circuit includes an AC input terminal 10, a transformer 20 (T1), a transformer control module 30, a voltage regulation feedback module 40, a main control chip 50 (U2), and a wireless charging output module 60. The AC input terminal 10 is connected to the primary terminal of the transformer 20 (T1) and the transformer control module 30. The secondary terminal of the transformer 20 (T1) is connected to the wireless charging output module and the voltage regulation feedback module 40. The transformer control module 30 is connected to the primary terminal of the transformer 20 (T1) and the voltage regulation feedback module 40. The main control chip 50 (U2) is connected to the voltage regulation feedback module 40 and the wireless charging output module 60. Among them, the main control chip 50 (U2) outputs a PWM signal based on the voltage output from the secondary terminal of the transformer 20 (T1). The voltage regulation feedback module 40 outputs a feedback voltage based on the secondary voltage and the PWM signal. The transformer control module 30 controls and adjusts the voltage output from the secondary terminal of the transformer 20 (T1) based on the feedback voltage.

[0029] In the embodiment of the present utility model, by providing an AC input terminal 10, a transformer 20 (T1), a transformer control module 30, a voltage regulation feedback module 40, a main control chip 50 (U2), and a wireless charging output module 60, the AC input terminal 10 is connected to the primary terminal of the transformer 20 (T1) and the transformer control module 30, the secondary terminal of the transformer 20 (T1) is connected to the wireless charging output module and the voltage regulation feedback module 40, the transformer control module 30 is connected to the primary terminal of the transformer 20 (T1) and the voltage regulation feedback module 40, and the main control chip 50 (U2) is connected to the voltage regulation feedback module 40 and the wireless charging output module 60. By adjusting the circuit structure, the main control chip 50 (U2) directly adjusts the feedback voltage of the voltage regulation feedback module 40 according to the secondary voltage output from the secondary terminal of the transformer 20 (T1). Furthermore, the transformer control module 30 controls and adjusts the voltage output from the secondary terminal of the transformer 20 (T1) based on the feedback voltage to supply a suitable voltage to the wireless charging output module 60, optimizing the overall wireless charging circuit, saving the original DC-DC conversion circuit of the wireless charger, reducing the volume of the overall circuit, and lowering the cost of the overall circuit. And because the DC-DC conversion circuit is saved, the circuit efficiency loss is reduced.

[0030] Among them, the main control chip 50 (U2) can output a PWM signal based on a voltage signal through an existing chip. For example, the main control chip 50 (U2) uses chips with models such as CV90367 and CV90368.

[0031] Reference Figure 1 、 Figure 3 and Figure 4 , the voltage regulation feedback module 40 includes a voltage regulator chip 41 (U1) and a voltage sampling unit 42. The reference terminal of the voltage regulator chip 41 (U1) is connected to the voltage division node of the voltage sampling unit 42 and the main control chip 50 (U2), the anode is grounded, the cathode is connected to the transformer control module 30, one end of the voltage sampling unit 42 is connected to the secondary terminal of the transformer 20 (T1), and the other end is grounded.

[0032] By providing the voltage sampling unit 42, the voltage sampling unit 42 can sample and obtain the secondary voltage output from the secondary terminal of the transformer 20 (T1). The main control chip 50 (U2) receives the voltage sampled by the voltage sampling unit 42 and then outputs a PWM signal, and the PWM signal is transmitted to the reference terminal of the voltage regulator chip 41 (U1). The reference terminal of the voltage regulator chip 41 (U1) receives the voltage sampled by the voltage sampling unit 42 and the PWM signal transmitted by the main control chip 50 (U2). Under the action of the two, the voltage regulator chip 41 (U1) changes the internal transistor current through internal reference comparison, thereby changing the feedback voltage output by itself and transmitting the feedback voltage to the transformer control module 30.

[0033] In specific implementation, the voltage regulator chip 41 (U1) can adopt chips such as TL431, LM431, YL431, KA431, etc. In this embodiment, the voltage regulator chip 41 (U1) preferably adopts a TL431 chip. The TL431 chip is a programmable precision voltage reference, a three-terminal programmable integrated circuit, used to provide a stable reference voltage. The TL431 chip contains a comparator and an adjustable voltage reference source, and controls the output by comparing the input voltage and the reference voltage. When the input voltage increases, the internal comparator of the TL431 chip will compare the voltage between the cathode and the reference terminal. If the cathode voltage is higher than the reference voltage, the TL431 chip will adjust its output to reduce the cathode voltage so as to keep the difference between the cathode and the reference voltage within a stable range.

[0034] Further, referring to Figure 1 , Figure 3 and Figure 4 , the voltage sampling unit 42 includes a first resistor R1, a second resistor R2, and a third resistor R3. The first resistor R1, the second resistor R2, and the third resistor R3 are connected in series in sequence. The series connection node of the second resistor R2 and the third resistor R3 is connected to the main control chip 50 (U2), the cathode of the voltage regulator chip 41 (U1), and the reference terminal. The other end of the first resistor R1 is connected to the secondary terminal of the transformer 20 (T1), and the other end of the third resistor R3 is grounded.

[0035] By setting the first resistor R1, the second resistor R2, and the third resistor R3 to be connected in series in sequence to form the voltage sampling unit 42, the secondary voltage output from the primary terminal of the transformer 20 (T1) is sampled and transmitted to the main control chip 50 (U2) and the voltage regulator chip 41 (U1), and the circuit structure is simple.

[0036] Referring to Figure 1 , Figure 3 and Figure 4 , the wireless charging circuit further includes an optocoupler U3. The input terminal of the optocoupler U3 is connected to the secondary terminal of the transformer 20 (T1) and the cathode of the voltage regulator chip 41 (U1), and the output terminal of the optocoupler U3 is connected to the transformer control module 30.

[0037] The optocoupler U3 is an electronic component composed of a light-emitting diode (LED) and a photosensitive diode (photo transistor), used to isolate the input and output parts in the circuit. By setting the optocoupler U3, the feedback voltage output by the voltage regulator chip 41 (U1) is transmitted to the transformer control module 30 connected to the primary terminal of the transformer 20 (T1) through the optocoupler U3, realizing electrical isolation between the high-voltage part circuit and the low-voltage part circuit, realizing isolated transmission of the feedback voltage between the high-voltage part circuit and the low-voltage part circuit, and reducing the mutual interference between the high-voltage part circuit and the low-voltage part circuit.

[0038] Reference Figure 1 、 Figure 3 and Figure 4 , the transformer control module 30 includes a power management chip U4. The power management chip U4 is connected to the output end of the optocoupler U3, the AC input end 10, and the primary end of the transformer 20 (T1). The power management chip U4 controls and adjusts the secondary voltage at the secondary end of the transformer 20 (T1) based on the second voltage transmitted by the optocoupler U3.

[0039] By setting the power management chip U4, a control signal can be output based on the feedback voltage transmitted by the optocoupler U3 to control and adjust the voltage output at the secondary end of the transformer 20 (T1), so as to output an appropriate voltage to supply the wireless charging output module 60.

[0040] In specific implementation, the power management chip U4 can adopt an existing flyback power management chip U4. The flyback power management chip U4 integrates a PWM / PFM circuit, a MOS drive circuit, a MOS transistor and a current detection circuit, a voltage feedback circuit, etc. After receiving the feedback voltage transmitted by the optocoupler U3, the power management chip U4 adjusts the drive pulse width or frequency of the internal MOS transistor. The internal MOS transistor performs switching actions according to the adjusted drive pulse width or frequency, adjusts the working state of the transformer 20 (T1), and adjusts the voltage output at the secondary end of the transformer 20 (T1). The power management chip U4 has a high circuit integration degree and occupies a relatively small circuit volume, further simplifying the circuit structure.

[0041] Reference Figure 1 、 Figures 3 to 5 , the wireless charging output module 60 includes a full-bridge drive unit 61 and a wireless charging coil 62. The full-bridge drive unit 61 is connected to the wireless charging coil 62, the main control chip 50 (U2), and the secondary end of the transformer 20 (T1).

[0042] The secondary end of the transformer 20 (T1) is connected to the full-bridge drive unit 61 to provide an appropriate voltage for the full-bridge drive unit 61. By setting the full-bridge drive unit 61, the main control chip 50 (U2) can control the full-bridge drive unit 61 to make the wireless charging coil 62 adapt to the resonance points at different frequencies. The alternating current at both ends of the wireless charging coil 62 is induced to the receiving coil, thereby performing power transmission. The circuit schematic diagram of the full-bridge drive unit 61 is as Figure 5As shown, the full-bridge drive unit includes four full-bridge drive MOS transistors, namely the first MOS transistor Q1Q1, the second MOS transistor Q2Q2, the third MOS transistor Q3Q3, and the fourth MOS transistor Q4Q4. The main control chip 50 (U2) outputs control signals to the four gate pins of the first MOS transistor Q1Q1 and the second MOS transistor Q2Q2, alternately turning on the first MOS transistor Q1Q1 and the second MOS transistor Q2Q2, causing the wireless charging coil 62 and the capacitor connected to the wireless charging coil 62 to resonate. The alternating current at both ends of the wireless charging coil 62 induces the receiving coil at the charging receiving end, thereby enabling power transmission. The third MOS transistor Q3Q3 and the fourth MOS transistor Q4Q4 serve as resonant capacitor switching MOS transistors. The main control chip 50 (U2) controls the conduction of the third MOS transistor Q3Q3 or the fourth MOS transistor Q4Q4, corresponding to the capacitor outside the third MOS transistor Q3Q3 or the capacitor outside the fourth MOS transistor Q4Q4, so as to achieve resonance points at different frequencies.

[0043] Reference Figures 2 to 6 , the wireless charging circuit further includes a sampling and demodulation circuit module 70. The sampling and demodulation circuit module 70 is used to collect the modulation signal of the external charging receiving end. The sampling and demodulation circuit module 70 is connected to the main control module and the wireless charging output module 60.

[0044] By setting the sampling and demodulation circuit module 70, the main control chip 50 (U2) demodulates the modulation signal of the external charging receiving end in combination with the sampling and demodulation circuit module 70. The main control chip 50 (U2) outputs a PWM drive level in combination with the voltage output from the secondary side of the transformer 20 (T1) and the signal demodulated by the sampling and demodulation circuit module 70 to control the full-bridge drive unit 61 to output different powers. The circuit schematic diagram of the sampling and demodulation circuit module 70 is as Figure 6 shown. The sampling and demodulation circuit module 70 can be implemented by an operational amplifier and its peripheral circuits. The chip model of the operational amplifier is such as LM358.

[0045] Reference Figure 2 and Figure 3 , the wireless charging circuit further includes a rectification and filtering module 80. The rectification and filtering module 80 is used to convert the low-voltage alternating current voltage into a low-voltage direct current voltage. The input end of the rectification and filtering module 80 is connected to the secondary side of the transformer 20 (T1), and the output end of the rectification and filtering module 80 is connected to the voltage regulation and feedback module 40 and the wireless charging output module 60.

[0046] By setting up the rectification and filtering module 80, the low-voltage alternating current voltage output from the secondary terminal of the transformer 20 (T1) is converted into a low-voltage direct current voltage, which facilitates the wireless charging output module 60 to directly use the appropriate low-voltage direct current voltage for subsequent power supply. The rectification and filtering module 80 can also smooth the output direct current voltage, reduce voltage fluctuations, and ensure a stable voltage output, providing a stable voltage for the wireless charging output module 60 and the voltage regulation and feedback module 40.

[0047] Specifically, referring to Figure 2 and Figure 3 , the rectification and filtering module 80 includes a filtering capacitor C1 and a first diode D1. The positive pole of the filtering capacitor C1 is connected to the voltage regulation and feedback module 40, the wireless charging output module 60, and the negative pole of the first diode D1. The negative pole of the filtering capacitor C1 is connected to the secondary terminal of the transformer 20 (T1) and the ground terminal, and the positive pole of the first diode D1 is connected to the secondary terminal of the transformer 20 (T1).

[0048] By setting up the filtering capacitor C1 and the first diode D1, the low-voltage alternating current voltage output from the secondary terminal of the transformer 20 (T1) is converted into a low-voltage direct current voltage, and the high-frequency noise and fluctuations in the low-voltage alternating current voltage are removed through the filtering capacitor C1 to provide a more stable direct current output.

[0049] Referring to Figure 2 and Figure 3 , the wireless charging circuit includes a rectification circuit module 90, which is used to convert the high-voltage alternating current voltage into a high-voltage direct current voltage. The input terminal of the rectification circuit module 90 is connected to the alternating current input terminal 10, and the output terminal of the rectification circuit module 90 is connected to the input terminal of the transformer 20 (T1) and the transformer control module 30.

[0050] By setting up the rectification circuit module 90, the high-voltage alternating current voltage at the alternating current input terminal 10 is converted into a high-voltage direct current voltage to meet the subsequent demand for the direct current voltage.

[0051] Specifically, referring to Figure 2 and Figure 3 , the rectification circuit module 90 includes a second diode D2, a third diode D3, a fourth diode D4, and a fifth diode D5. The second diode D2 is connected in parallel with the third diode D3, and the fourth diode D4 is connected in parallel with the fifth diode D5. The parallel positive node of the second diode D2 and the third diode D3 is connected to the alternating current input terminal 10, and the parallel negative node is connected to the primary terminal of the transformer 20 (T1). The parallel positive node of the fourth diode D4 and the fifth diode D5 is connected to the ground terminal, and the negative node is connected to the alternating current input terminal 10.

[0052] By setting the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5, a rectifier bridge can be formed to rectify the high-voltage alternating current voltage input at the AC input terminal 10 and convert it into a high-voltage direct current voltage to provide the high-voltage direct current voltage for the transformer 20 (T1).

[0053] An embodiment of the present invention also provides a wireless charging device, including a wireless charging device housing, a circuit board, and the wireless charging circuit as described above. The wireless charging circuit is disposed on the circuit board, and the circuit board is encapsulated in the housing.

[0054] Reference Figures 1 to 6 , in this application, by integrating and optimizing the existing power adapter and wireless charger, adjusting the overall circuit structure, in the wireless charging circuit, the main control chip 50 (U2) directly adjusts the feedback voltage of the voltage regulation feedback module 40 according to the voltage output from the secondary end of the transformer 20 (T1). Furthermore, the transformer control module 30 controls and adjusts the voltage output from the secondary end of the transformer 20 (T1) to supply a suitable voltage to the wireless charging output module 60 based on the feedback voltage, optimizing the overall wireless charging circuit, saving the original DC-DC conversion circuit of the wireless charger, reducing the volume of the overall circuit, and lowering the cost of the overall circuit. Since the DC-DC conversion circuit is saved, the circuit efficiency loss is reduced, the circuit efficiency of the wireless charging device is improved, and the wireless charging circuit is disposed on the circuit board, and the circuit board is encapsulated in the housing, overall saving the mold and material costs of the housing required for the original power adapter. The user does not need to carry an additional power adapter, bringing a certain degree of convenience to the user.

[0055] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features can be equivalently replaced; and all such modifications and replacements should fall within the protection scope of the appended claims of the present invention.

Claims

1. A wireless charging circuit, characterized in that, It includes an AC input terminal, a transformer, a transformer control module, a voltage regulation feedback module, a main control chip, and a wireless charging output module. The AC input terminal is connected to the primary terminal of the transformer and the transformer control module. The secondary terminal of the transformer is connected to the wireless charging output module and the voltage regulation feedback module. The transformer control module is connected to the primary terminal of the transformer and the voltage regulation feedback module. The main control chip is connected to the voltage regulation feedback module and the wireless charging output module. Among them, the main control chip outputs a PWM signal based on the secondary voltage output from the secondary terminal of the transformer. The voltage regulation feedback module outputs a feedback voltage based on the secondary voltage and the PWM signal. The transformer control module controls and adjusts the secondary voltage output from the secondary terminal of the transformer based on the feedback voltage.

2. The wireless charging circuit according to claim 1, wherein The voltage regulation feedback module includes a voltage regulator chip and a voltage sampling unit. The reference terminal of the voltage regulator chip is connected to the voltage division node of the voltage sampling unit and the main control chip, the anode is grounded, and the cathode is connected to the transformer control module. One end of the voltage sampling unit is connected to the secondary terminal of the transformer, and the other end is grounded.

3. The wireless charging circuit according to claim 2, wherein The voltage sampling unit includes a first resistor, a second resistor, and a third resistor. The first resistor, the second resistor, and the third resistor are connected in series in sequence. The series connection node of the second resistor and the third resistor is connected to the main control chip, the cathode of the voltage regulator chip, and the reference terminal. The other end of the first resistor is connected to the secondary terminal of the transformer, and the other end of the third resistor is grounded.

4. The wireless charging circuit according to claim 3, characterized in that, The wireless charging circuit further includes an optocoupler. The input terminal of the optocoupler is connected to the secondary terminal of the transformer and the cathode of the voltage regulator chip, and the output terminal of the optocoupler is connected to the transformer control module.

5. The wireless charging circuit according to claim 4, wherein, The transformer control module includes a power management chip. The power management chip is connected to the output terminal of the optocoupler, the AC input terminal, and the primary terminal of the transformer. The power management chip controls and adjusts the secondary voltage of the secondary terminal of the transformer based on the feedback voltage transmitted by the optocoupler.

6. The wireless charging circuit according to any one of claims 1 to 5, characterized in that The wireless charging output module includes a full-bridge drive unit and a wireless charging coil. The full-bridge drive unit is connected to the wireless charging coil, the main control chip, and the secondary terminal of the transformer.

7. The wireless charging circuit according to any one of claims 1 to 5, characterized in that The wireless charging circuit further includes a sampling and demodulation circuit module. The sampling and demodulation circuit module is used to collect the modulation signal of an external charging receiving end. The sampling and demodulation circuit module is connected to the main control chip and the wireless charging output module.

8. The wireless charging circuit according to any one of claims 1 to 5, characterized in that, The wireless charging circuit further includes a rectification and filtering module. The rectification and filtering module is used to convert a low-voltage AC voltage into a low-voltage DC voltage. The input terminal of the rectification and filtering module is connected to the secondary terminal of the transformer, and the output terminal of the rectification and filtering module is connected to the voltage regulation feedback module and the wireless charging output module.

9. The wireless charging circuit according to any one of claims 1 to 5, characterized in that, The wireless charging circuit includes a rectification circuit module. The rectification circuit module is used to convert a high-voltage AC voltage into a high-voltage DC voltage. The input terminal of the rectification circuit module is connected to the AC input terminal, and the output terminal of the rectification circuit module is connected to the input terminal of the transformer and the transformer control module.

10. A wireless charging device, characterized in that, It includes a housing, a circuit board, and the wireless charging circuit as described in any one of claims 1-9. The wireless charging circuit is disposed on the circuit board, and the circuit board is encapsulated in the housing.

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