Transmitting end voltage demodulation circuit and wireless charging device using same

Abstract

The utility model provides a transmitting end voltage demodulation circuit, which is applied to a wireless charging device and comprises a low-pass filter circuit, an operational amplifier circuit and a square wave shaping circuit. The low-pass filter circuit is used for filtering the voltage modulation signal to obtain a first voltage signal; when demodulation fails, the operation amplification circuit is controlled to work, an alternating current signal in the first voltage signal after low-pass filtering is amplified, and the square wave shaping circuit outputs a demodulation signal based on the amplified signal; abnormal communication between the electronic equipment and the transmitting end caused by misalignment of the transmitting coil and the receiving coil or small communication demodulation depth due to other reasons can be avoided, and the reliability of charging is ensured. Before charging or when demodulation is normal, the operational amplifier circuit is controlled not to work, the square wave shaping circuit directly outputs the demodulation signal based on the first voltage signal, and at the moment, the power consumption of the circuit can be saved by controlling the operational amplifier circuit not to work.

Description

Technical Field

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

[0002] Wireless charging is a common charging method in daily life. It transfers energy from the transmitter to the receiver through coil coupling, and converts the energy into electrical energy at the receiver that can power electronic devices such as mobile phones. At the receiver, the signal is generally transmitted to the transmitter by modulation according to the power demand of the electronic device or the status of the electronic device. The transmitter demodulates the modulated signal to adjust the power and other information transmitted to the receiver. When the transmitter demodulates the voltage modulated signal, when the coils between the transmitter and the receiver are not aligned, the mutual inductance will be reduced, resulting in a smaller communication demodulation depth, which may cause the demodulation failure of the transmitter, and the electronic device cannot communicate with the transmitter, resulting in charging interruption. Therefore, it is necessary to provide a new voltage demodulation circuit to solve the problems existing in the prior art. Utility Model Content

[0003] In order to solve the above technical problems, the utility model provides a transmitting end voltage demodulation circuit and a wireless charging device using the same.

[0004] According to a first aspect of the utility model, a transmitting end voltage demodulation circuit is provided, which is applied to a wireless charging device, wherein the transmitting end includes a transmitting coil, an inverter, a voltage demodulation circuit and a transmitting end control module, wherein the voltage demodulation circuit receives a voltage modulation signal via the transmitting coil, and demodulates the voltage modulation signal to obtain a demodulation signal; the transmitting end control module controls the operation of the inverter based on the demodulation signal; and is characterized in that the voltage demodulation circuit includes:

[0005] A low-pass filter circuit receives the voltage modulation signal and is used to filter the voltage modulation signal to obtain a first voltage signal;

[0006] A square wave shaping circuit receives a second voltage signal and obtains a demodulated signal based on a second AC signal in the second voltage signal;

[0007] An operational amplifier circuit, wherein the transmitting end control module receives the demodulated signal and determines whether the demodulation is valid based on the demodulated signal; before charging or when the demodulated signal is valid, the operational amplifier circuit is controlled not to work, at which time, the second voltage signal is the same as the first voltage signal; when the demodulated signal fails, the operational amplifier circuit is controlled to work, and the first AC signal in the first voltage signal is amplified to output a second voltage signal.

[0008] Optionally, before charging or when the demodulation signal is valid, the input end of the operational amplifier circuit is short-circuited to the output end thereof.

[0009] Optionally, the operational amplifier circuit includes a first capacitor and an operational amplifier unit; the first capacitor is used to filter out the DC signal in the first voltage signal to obtain the first AC signal; when the operational amplifier unit is working, the operational amplifier circuit is used to amplify the first AC signal to obtain the second voltage signal.

[0010] Optionally, a first switch is provided between the input terminal and the output terminal of the operational amplifier circuit; a second switch is provided between the power supply terminal and the power supply voltage of the operational amplifier circuit;

[0011] Before charging or when the demodulation signal is valid, the first switch is in the on state and the second switch is in the off state; when the demodulation signal is invalid, the first switch is in the off state and the second switch is in the on state.

[0012] Optionally, the square wave shaping circuit includes a second capacitor and a comparison circuit; the second capacitor is used to filter out the DC signal in the second voltage signal to obtain the second AC signal; the second AC signal is connected to the first input terminal of the comparison circuit, the second input terminal of the comparison circuit is connected to the reference voltage, and the demodulated signal is obtained based on the output of the comparison circuit.

[0013] Optionally, a direct current voltage is superimposed on the first input terminal of the comparison circuit, the direct current voltage is equal to the reference voltage, and the reference voltage is a voltage greater than zero.

[0014] Optionally, the square wave shaping circuit also includes a first resistor to a fourth resistor, the first resistor and the second resistor are arranged between the power supply voltage and the ground terminal, and the common node of the first resistor and the second resistor is connected to the first input terminal of the comparison circuit; the third resistor and the fourth resistor are arranged between the power supply voltage and the ground terminal, and the second input terminal of the comparison circuit is connected to the common node of the third resistor and the fourth resistor.

[0015] Optionally, the bandwidth of the low-pass filter circuit is a first bandwidth, which is smaller than a second bandwidth; the second bandwidth is the bandwidth of the low-pass filter circuit when the voltage demodulation circuit is not added with an operational amplifier circuit.

[0016] The present application also provides a wireless charging device, which includes a transmitting end and a receiving end, wherein the transmitting end includes a transmitting coil, and the receiving end includes a receiving coil, and the energy from the transmitting end is converted into energy that can power a load through the coupling effect between the transmitting coil and the receiving coil, and is characterized in that the transmitting end includes the voltage demodulation circuit described above.

[0017] Optionally, a modulation capacitor and a switch tube connected in series are provided at the receiving end, and the state of the switch tube is controlled to control whether the modulation capacitor is added to the resonant circuit of the receiving end to adjust the voltage modulation signal.

[0018] The beneficial effects of the utility model include at least:

[0019] The utility model provides a transmitting end voltage demodulation circuit and a wireless charging device using the same. The voltage demodulation circuit includes a low-pass filtering circuit, an operational amplifier circuit and a square wave shaping circuit. The low-pass filtering circuit is used to filter the voltage modulation signal to obtain a first voltage signal. When the demodulation fails, the operational amplifier circuit is controlled to work to amplify the AC signal in the first voltage signal after the low-pass filtering, and the square wave shaping circuit outputs a demodulation signal based on the amplified signal. At this time, the abnormal communication between the electronic device and the transmitting end caused by the misalignment of the transmitting coil and the receiving coil or the small communication demodulation depth caused by other reasons can be avoided, thereby ensuring the reliability of charging. Before charging or when the demodulation is normal, the operational amplifier circuit is controlled not to work, and the square wave shaping circuit directly outputs the demodulation signal based on the first voltage signal. At this time, by controlling the operational amplifier circuit not to work, the circuit power consumption can be saved.

[0020] Furthermore, the bandwidth of the low-pass filter circuit can be set to reduce its bandwidth, further filter out noise interference signals, and improve its noise suppression capability.

[0021] It should be noted that the above general description and the following detailed description are merely exemplary and explanatory and cannot limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a transmitter is shown;

[0023] Figure 2 A schematic diagram of a transmitting end voltage demodulation circuit provided by the utility model is shown;

[0024] Figure 3 A schematic diagram of an operational amplifier circuit is shown;

[0025] Figure 4 A schematic diagram of a square wave shaping circuit is shown;

[0026] Figure 5 A schematic diagram of a wireless charging device is shown. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively with reference to the relevant drawings. The drawings provide preferred embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0028] Figure 1 The figure shows a schematic diagram of a voltage demodulation circuit at the transmitting end, which is applied to a wireless charging device; the transmitting end Tx includes a transmitting coil L1, an inverter, a capacitor Cr1, a voltage demodulation circuit 10 and a transmitting end control module; Figure 1 In the embodiment, the inverter is composed of the first switch tube Q1 to the fourth switch tube Q4; the transmitting end Tx is used to convert the power Vin into AC power through the inverter and send it out through the transmitting coil L1; wherein the power Vin can be obtained by AC power conversion. The voltage demodulation circuit 10 receives the voltage modulation signal Vtank through the transmitting coil L1, and demodulates the voltage modulation signal Vtank to obtain a demodulation signal; the transmitting end control module controls the operation of the inverter based on the demodulation signal; in Figure 1 In the embodiment, the transmitter control module outputs the first control signal PWM1 to the fourth control signal PWM4 based on the demodulated signal, and controls the operation of the first switch tube to the fourth switch tube based on the first control signal to the fourth control signal. For example, the power sent by the transmitter Tx can be adjusted by adjusting the frequency and / or duty cycle of the first switch tube to the fourth switch tube.

[0029] Figure 2The figure shows a schematic diagram of a voltage demodulation circuit at the transmitting end provided by the utility model, wherein the voltage demodulation circuit 10 includes a low-pass filter circuit and a square wave shaping circuit 30. The low-pass filter circuit receives a voltage modulation signal Vtank, and is used to filter the voltage modulation signal Vtank to obtain a first voltage signal V1; wherein the first voltage signal V1 is a quasi-sine wave with a small amplitude and a DC bias. The square wave shaping circuit receives a second voltage signal V2 at its input end, and obtains a demodulation signal VDMO based on a second AC signal in the second voltage signal V2. In the present application, according to the working state of the circuit, the second voltage signal V2 can be the same signal as the first voltage signal V1, or it can be a signal after the first voltage signal V1 is amplified. The working principle is further explained below. The voltage demodulation circuit 10 also includes an operational amplifier circuit 20. The transmitter control module receives the demodulation signal VDMO and determines whether the demodulation is valid based on the demodulation signal VDMO (the transmitter control module can decode the demodulation signal VDMO based on the communication protocol to determine whether the demodulation is invalid); before charging or when the demodulation signal is valid, the operational amplifier circuit 20 is controlled not to work. At this time, the second voltage signal is the same as the first voltage signal; when the demodulation signal fails (for example, due to the small demodulation depth, the demodulation fails due to the limitation of the hysteresis threshold of the comparison circuit in the square wave shaping circuit), the operational amplifier circuit is controlled to work. At this time, the input end of the operational amplifier circuit receives the first voltage signal, amplifies the first AC signal in the first voltage signal, and outputs the second voltage signal at its output end. That is, when the voltage demodulation circuit is working, the present application determines whether the operational amplifier circuit is working based on whether the demodulation signal fails. When the demodulation fails, the operational amplifier circuit is controlled to work, and the AC signal in the first voltage signal after low-pass filtering is amplified. The square wave shaping circuit then outputs the demodulation signal based on the amplified signal. At this time, the abnormal communication between the electronic device and the transmitting end can be avoided, and the reliability of charging can be ensured; before charging or when the demodulation is normal, the operational amplifier circuit is controlled not to work, and the square wave shaping circuit directly outputs the demodulation signal based on the first voltage signal (at this time, the second voltage signal is the same as the first voltage signal). At this time, by controlling the operational amplifier circuit not to work, the circuit power consumption can be saved.

[0030] like Figure 2 As shown in the figure, a first switch S1 is provided at the input and output ends of the operational amplifier circuit, and the first switch S1 is controlled by a first switch control signal K1; the transmitting end control module outputs a first switch control signal K1 and a second switch control signal K2 based on the demodulation signal VDMO; when the demodulation signal fails, the first switch S1 is controlled to be in a disconnected state by the first switch control signal K1, and the operational amplifier circuit is controlled to be in a working state by the second control signal K2; before charging or when demodulation is effective, the first switch S1 is controlled to be in a conducting state by the first switch control signal K1, and the operational amplifier circuit is controlled to be non-working by the second switch control signal K2.

[0031] Furthermore, the operational amplifier circuit 20 includes a first capacitor C1 and an operational amplifier unit U1. The first capacitor C1 is used to filter out the DC voltage signal in the first voltage signal V1 to obtain a first AC signal. The power supply end of the operational amplifier unit U1 is connected to the power supply voltage VCC through the second switch S2, and the second switch S2 is controlled by the second switch control signal K2; when the operational amplifier unit U1 is required to work, the second switch S2 is controlled to be closed, and the power supply voltage VCC can act normally on the power supply end of the operational amplifier unit U1, so that the operational amplifier unit U1 can work normally; when the operational amplifier unit U1 is not required to work, the second switch S2 is controlled to be disconnected, at this time, the operational amplifier unit U1 cannot be powered normally, so that the operational amplifier unit U1 does not work. Specifically, Figure 3 FIG. 2 is a schematic diagram of an operational amplifier circuit 20. Figure 3 As shown in, the first voltage signal V1 is connected to the first input terminal of the operational amplifier unit U1 after passing through the first capacitor C1; the operational amplifier circuit 20 is also provided with resistors R5 to R8 and capacitor C4; the second switch S2 and resistors R5 and R6 are connected in series between the power supply voltage VCC and the ground terminal, and the common node of resistors R5 and R6 is also connected to the first input terminal of the operational amplifier unit U1; resistors R7, R8 and capacitor C4 are connected between the output terminal of the operational amplifier unit U1 and the ground terminal. When the operational amplifier circuit needs to work, the first switch S1 is opened, the second switch S2 is closed, and the Figure 3 The circuit structure can amplify the first AC signal and obtain a second voltage signal V2 at its output end. Figure 3 The structure of the operational amplifier circuit is only one example in the present application, and the present application is not limited thereto, and other circuit structures may also be used to achieve the same function.

[0032] Furthermore, based on the introduction of the operational amplifier circuit, the bandwidth of the low-pass filter circuit can be set to reduce its bandwidth, further filter out noise interference signals, and enhance its noise suppression capability.

[0033] Furthermore, the square wave shaping circuit 30 includes a second capacitor C2 and a comparison circuit U2; the second capacitor C2 is used to filter out the DC signal in the second voltage signal V2 to obtain a second AC signal; the second AC signal is connected to the first input terminal of the comparison circuit U2, and the second input terminal of the comparison circuit U2 is connected to the reference voltage, and the demodulation signal VDMO is obtained based on the output of the comparison circuit U2. Furthermore, a DC voltage can be superimposed on the first input terminal of the comparison circuit U2, and the DC voltage is equal to the reference voltage. At this time, the reference voltage can be a voltage greater than zero. Specifically, Figure 4 A schematic diagram of a square wave shaping circuit 30 is shown. Figure 4As shown in , the square wave shaping circuit 30 also includes a first resistor R1 to a fourth resistor R4. The first resistor R1 and the second resistor R2 are arranged between the power supply voltage VCC and the ground terminal, and the common node of the first resistor R1 and the second resistor R2 is connected to the first input terminal of the comparison circuit U2; the third resistor R3 and the fourth resistor R4 are arranged between the power supply voltage VCC and the ground terminal, and the second input terminal of the comparison circuit U2 is connected to the common node of the third resistor R3 and the fourth resistor R4. At this time, the DC voltage superimposed on the first input terminal of the comparison circuit U2 is the voltage on the second resistor R2; by setting the resistance values ​​of the first resistor R1 to the fourth resistor R4, the DC voltages at both ends of the comparison circuit U2 can be made equal. Compared with the method of directly comparing the second AC signal with the zero voltage to obtain the demodulated signal VDMO, the method of using Figure 4 The method shown can make the comparison circuit U2 easier to design and the output reliability higher.

[0034] Furthermore, the present application also provides a wireless charging device, wherein the transmitting end of the wireless charging device includes the voltage demodulation circuit described above, Figure 5 The figure shows a schematic diagram of a wireless charging device. Figure 5 As shown in the figure, the wireless charging device includes a transmitter Tx and a receiver Rx, wherein the configuration of the transmitter Tx is described above and will not be repeated here. The receiver Rx includes a receiving coil L2 and a capacitor Cr2, and the energy from the transmitter is converted into energy that can power the load RL through the coupling effect of the transmitter coil L1 and the receiving coil L2 ( Figure 5 Vout is used as an indicator in the figure). Figure 5 The diagram shows how the energy from the transmitter is converted into energy that can power the load through the rectifier module in the receiver. Figure 5 As shown in the figure, the receiving end is also provided with a modulation capacitor C3 and a switch tube Q5 connected in series, and a modulation capacitor C4 and a switch tube Q6 connected in series. By controlling the switching state of the switch tube Q5 and the switch tube Q6, it is possible to control whether the corresponding modulation capacitor is added to the resonant circuit of the receiving end, that is, the voltage modulation signal Vtank can be adjusted by controlling whether the capacitor C3 and the capacitor C4 are connected or not.

[0035] In summary, the present application provides a transmitting end voltage demodulation circuit and a wireless charging device using the same, wherein the voltage demodulation circuit includes a low-pass filtering circuit, an operational amplifier circuit and a square wave shaping circuit; the low-pass filtering circuit is used to filter the voltage modulation signal to obtain a first voltage signal; when the demodulation fails, the operational amplifier circuit is controlled to work, and the AC signal in the first voltage signal after the low-pass filtering is amplified, and the square wave shaping circuit then outputs a demodulated signal based on the amplified signal. At this time, the abnormal communication between the electronic device and the transmitting end caused by the misalignment of the transmitting coil and the receiving coil or the small communication demodulation depth caused by other reasons can be avoided, thereby ensuring the reliability of charging; before charging or when the demodulation is normal, the operational amplifier circuit is controlled not to work, and the square wave shaping circuit directly outputs a demodulated signal based on the first voltage signal. At this time, by controlling the operational amplifier circuit not to work, the circuit power consumption can be saved.

[0036] Furthermore, the bandwidth of the low-pass filter circuit can be set to reduce its bandwidth, further filter out noise interference signals, and improve its noise suppression capability.

[0037] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A transmitting end voltage demodulation circuit, applied to a wireless charging device, wherein the transmitting end comprises a transmitting coil, an inverter, a voltage demodulation circuit and a transmitting end control module, wherein the voltage demodulation circuit receives a voltage modulation signal via the transmitting coil and demodulates the voltage modulation signal to obtain a demodulated signal; The transmitting end control module controls the operation of the inverter based on the demodulated signal; characterized in that: The voltage demodulation circuit comprises: A low-pass filter circuit receives the voltage modulation signal and is used to filter the voltage modulation signal to obtain a first voltage signal; A square wave shaping circuit receives a second voltage signal and obtains a demodulated signal based on a second AC signal in the second voltage signal; An operational amplifier circuit, wherein the transmitting end control module receives the demodulated signal and determines whether the demodulation is valid based on the demodulated signal; before charging or when the demodulated signal is valid, the operational amplifier circuit is controlled not to work, at which time, the second voltage signal is the same as the first voltage signal; when the demodulated signal fails, the operational amplifier circuit is controlled to work, and the first AC signal in the first voltage signal is amplified to output a second voltage signal.

2. The voltage demodulation circuit according to claim 1, characterized in that: Before charging or when the demodulation signal is valid, the input end of the operational amplifier circuit is short-circuited with its output end.

3. The voltage demodulation circuit according to claim 1, characterized in that: The operational amplifier circuit includes a first capacitor and an operational amplifier unit; the first capacitor is used to filter out the DC signal in the first voltage signal to obtain the first AC signal; when the operational amplifier unit is working, the operational amplifier circuit is used to amplify the first AC signal to obtain the second voltage signal.

4. The voltage demodulation circuit according to claim 2, characterized in that: A first switch is provided between the input terminal and the output terminal of the operational amplifier circuit; a second switch is provided between the power supply terminal and the power supply voltage of the operational amplifier circuit; Before charging or when the demodulation signal is valid, the first switch is in the on state and the second switch is in the off state; when the demodulation signal is invalid, the first switch is in the off state and the second switch is in the on state.

5. The voltage demodulation circuit according to claim 1, characterized in that: The square wave shaping circuit includes a second capacitor and a comparison circuit; the second capacitor is used to filter out the DC signal in the second voltage signal to obtain the second AC signal; the second AC signal is connected to the first input terminal of the comparison circuit, the second input terminal of the comparison circuit is connected to the reference voltage, and the demodulated signal is obtained based on the output of the comparison circuit.

6. The voltage demodulation circuit according to claim 5, characterized in that: A direct current voltage is also superimposed on the first input terminal of the comparison circuit. The direct current voltage is equal to the reference voltage, and the reference voltage is a voltage greater than zero.

7. The voltage demodulation circuit according to claim 6, characterized in that: The square wave shaping circuit further includes a first resistor to a fourth resistor, the first resistor and the second resistor are arranged between the power supply voltage and the ground terminal, and a common node of the first resistor and the second resistor is connected to the first input terminal of the comparison circuit; The third resistor and the fourth resistor are arranged between the power supply voltage and the ground terminal, and the second input terminal of the comparison circuit is connected to a common node of the third resistor and the fourth resistor.

8. The voltage demodulation circuit according to claim 1, characterized in that: The bandwidth of the low-pass filter circuit is a first bandwidth, which is smaller than a second bandwidth; the second bandwidth is the bandwidth of the low-pass filter circuit when the voltage demodulation circuit is not added with an operational amplifier circuit.

9. A wireless charging device, comprising a transmitting end and a receiving end, wherein the transmitting end comprises a transmitting coil, and the receiving end comprises a receiving coil, and the energy from the transmitting end is converted into energy that can supply power to a load through the coupling effect between the transmitting coil and the receiving coil, characterized in that: The transmitting end comprises the voltage demodulation circuit according to any one of claims 1-8.

10. The wireless charging device according to claim 9, characterized in that: A modulation capacitor and a switch tube connected in series are provided at the receiving end. The state of the switch tube is controlled to control whether the modulation capacitor is added to the resonant circuit of the receiving end to adjust the voltage modulation signal.

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