Active rectification synchronization signal generation circuit, receiver and wireless charging system

Abstract

The present invention relates to the field of wireless charging technology, and particularly to an active rectification synchronization signal generation circuit, a receiver, and a wireless charging system. The active rectification synchronization signal generation circuit in the receiver of the wireless charging system generates a phase synchronization signal required for the active rectification circuit based on the output current of the resonant circuit, and includes: a high-frequency current sensor circuit that measures the output current of the resonant circuit and converts it into a corresponding voltage signal; a resonant filtering circuit that filters the voltage signal to obtain a processing result; and a high-frequency zero-crossing comparator circuit that generates a phase synchronization signal through the processing result. By means of the present invention, an accurate phase synchronization signal can be provided for the active rectification circuit of the wireless charging receiver, so as to achieve synchronous rectification and phase-shift control. During the implementation process, the oscillation problem of the active rectification circuit of the wireless charging system receiver can be significantly improved, and the phase-shift range and load range of the active rectification circuit can be effectively increased.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging, and particularly to an active rectification synchronization signal generation circuit, a receiver, and a wireless charging system. Background Art

[0002] As a non-contact charging method, wireless charging technology can be applied to scenarios such as electric vehicles, automated guided vehicles, and smart phones. A wireless charging system is divided into two parts: a transmitter and a receiver, where the receiver needs to rectify high-frequency current.

[0003] The active rectification circuit in the receiver has lower losses compared to the traditional diode rectification circuit, which helps to achieve higher transmission efficiency. However, when performing synchronous rectification or phase-shift control, the drive signal of the switching tube needs to be synchronized with the generator. Between the transmitter and the active rectification circuit, the voltage and current output by the resonant circuit of the wireless charging receiver are affected by the load and harmonic current. In the existing methods, directly using it as the synchronization source of the active rectification circuit will cause oscillation problems under high-resistance loads.

[0004] The information disclosed in this background art section is only intended to deepen the understanding of the overall background art of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The present invention provides an active rectification synchronization signal generation circuit, a receiver, and a wireless charging system, thereby effectively solving the problems pointed out in the background art.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An active rectification synchronization signal generation circuit, in the receiver of a wireless charging system, generates a phase synchronization signal required for the active rectification circuit based on the output current of the resonant circuit, including:

[0008] A high-frequency current sensor circuit that measures the output current of the resonant circuit and converts it into a corresponding voltage signal;

[0009] A resonant filter circuit that filters the voltage signal to obtain a processing result;

[0010] A high-frequency zero-crossing comparator circuit that generates the phase synchronization signal through the processing result.

[0011] Further, the high-frequency current sensor circuit measures the output current through a Hall current sensor.

[0012] Further, the bandwidth of the Hall current sensor is higher than the resonance frequency of the wireless charging system.

[0013] Further, the high-frequency current sensor circuit measures the output current through a current sampling resistor.

[0014] Further, the high-frequency current sensor circuit further includes an operational amplifier for amplifying or processing the voltage signal.

[0015] Further, the high-frequency current sensor circuit includes a Hall current sensor, a first input resistor, a first operational amplifier, and a first feedback resistor;

[0016] The input end of the Hall current sensor is connected to the output end of the resonance circuit;

[0017] The first operational amplifier includes an inverting terminal and a non-inverting terminal, and the first input resistor is connected between the output end of the Hall current sensor and the inverting terminal;

[0018] One end of the first feedback resistor is connected between the first input resistor and the inverting terminal, and the other end is connected to the output end of the first operational amplifier.

[0019] Further, the output voltage of the high-frequency current sensor circuit is calculated by the following formula:

[0020] ;

[0021] where V 3 is the output voltage of the high-frequency current sensor circuit, V 1 is the output voltage of the Hall current sensor, V 2 is the reference voltage input to the non-inverting terminal, R 2 is the resistance value of the first input resistor, R 3 is the resistance value of the first feedback resistor.

[0022] Further, the high-frequency current sensor circuit includes a current sampling resistor, a second input resistor, a third input resistor, a fourth input resistor, a second operational amplifier, and a second feedback resistor;

[0023] The second operational amplifier includes an inverting terminal and a non-inverting terminal. The second input resistor is connected between one end of the current sampling resistor and the inverting terminal, and the third input resistor is connected between the other end of the current sampling resistor and the non-inverting terminal;

[0024] One end of the second feedback resistor is connected between the second input resistor and the inverting terminal, and the other end is connected to the output terminal of the second operational amplifier.

[0025] One end of the fourth input resistor is connected between the third input resistor and the non-inverting terminal, and the other end is connected to the input terminal of the reference voltage for the non-inverting terminal.

[0026] Further, the output voltage of the high-frequency current sensor circuit is calculated by the following formula:

[0027] ;

[0028] where V 3 is the output voltage of the high-frequency current sensor circuit; V i+ and V i- are respectively the voltages at the connection terminals of the current sampling resistor with the second input resistor and the third input resistor; V 2 is the reference voltage input to the non-inverting terminal; R 4 is the resistance value of the second input resistor; R 5 is the resistance value of the third input resistor; R 6 is the resistance value of the second feedback resistor; R 7 is the resistance value of the fourth input resistor.

[0029] Further, the resonance filtering circuit includes a resistor, an inductor, and a capacitor;

[0030] The resistor is connected between the output terminal of the high-frequency current sensor circuit and the output terminal of the resonance filtering circuit;

[0031] The inductor and the capacitor form a parallel resonance circuit. One end of the parallel resonance circuit is connected to the output terminal of the resonance filtering circuit, and the other end is connected to the negative pole of the power supply.

[0032] Further, when the signal output by the high-frequency current sensor circuit lags, the resonance frequency of the parallel resonance circuit is adjusted to be higher than the resonance frequency of the wireless charging system to compensate for the delay caused by the high-frequency current sensor circuit, and the adjustment is achieved by adjusting the parameters of the inductor and the capacitor.

[0033] Further, the adjustment of the parameters of the inductor and the capacitor is based on the following formula:

[0034] ;

[0035] wherein, f 0 is the resonant frequency of the parallel resonant circuit, with the unit of Hz; L f is the inductance value of the inductor, with the unit of H; C f is the capacitance value of the capacitor, with the unit of F.

[0036] Further, when the transmission gain of the resonant filter circuit changes beyond the set range, the resonant frequency of the parallel resonant circuit is adjusted, and the adjustment amplitude is related to the change amplitude of the transmission gain.

[0037] Further, the calculation formula of the transmission gain of the resonant filter circuit is as follows:

[0038] ;

[0039] ;

[0040] wherein, G(ω) is the transmission gain; ω is the angular frequency of the wireless charging system, with the unit of rad / s; ω 0 is the resonant angular frequency of the parallel resonant circuit, with the unit of rad / s; L f is the inductance value of the inductor, with the unit of H; R f is the resistance value of the resistor, with the unit of Ω; f is the resonant frequency of the wireless charging system.

[0041] Further, the high-frequency zero-crossing comparator circuit includes a high-speed comparator, and the high-speed comparator includes a non-inverting terminal and an inverting terminal; the non-inverting terminal is connected to the output terminal of the resonant filter circuit, and the inverting terminal is connected to the negative pole of the power supply.

[0042] Further, the high-frequency zero-crossing comparator circuit includes a high-speed comparator, and the high-speed comparator includes a non-inverting terminal and an inverting terminal; the inverting terminal is connected to the output terminal of the resonant filter circuit, and the non-inverting terminal is connected to the negative pole of the power supply.

[0043] Further, the transmission delay of the high-speed zero-crossing comparator is in the order of nanoseconds.

[0044] A receiver for a wireless charging system, including a resonant circuit and an active rectifier circuit, further includes the active rectifier synchronization signal generation circuit as described above;

[0045] The active rectification synchronization signal generation circuit generates the required phase synchronization signal for the active rectification circuit based on the output current of the resonant circuit.

[0046] Further, the active rectification circuit is a bridge rectification circuit, and each half-bridge of the bridge rectification circuit is two MOSFETs.

[0047] Further, the active rectification circuit is a bridge rectification circuit, the upper transistors of the bridge rectification circuit are two diodes, and the lower transistors are two MOSFETs.

[0048] Further, the active rectification circuit is a bridge rectification circuit, one half-bridge of the bridge rectification circuit is two MOSFETs, and the other half-bridge is two diodes.

[0049] A wireless charging system includes a transmitter and a receiver;

[0050] The receiver includes a resonant circuit and an active rectification circuit, and further includes the active rectification synchronization signal generation circuit as described above;

[0051] The active rectification synchronization signal generation circuit generates the required phase synchronization signal for the active rectification circuit based on the output current of the resonant circuit.

[0052] Through the technical solution of the present invention, the following technical effects can be achieved:

[0053] The present invention provides an active rectification synchronization signal generation circuit for a wireless charging system, which can provide an accurate phase synchronization signal for the active rectification circuit of the wireless charging receiver, so as to achieve synchronous rectification and phase shift control. During the implementation process, the oscillation problem of the active rectification circuit of the wireless charging system receiver can be significantly improved, and the phase shift range and load range of the active rectification circuit can be effectively increased. Description of the Drawings

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0055] Figure 1 It is a schematic diagram of the active rectification synchronization signal generation circuit of the present invention;

[0056] Figure 2 For Figure 1 Compared with

[0057] Figure 3 Compared with Figure 1 and Figure 2 a partial schematic diagram of the active rectification synchronization signal generation circuit after the high-frequency zero-crossing comparator circuit changes;

[0058] Figure 4 a schematic diagram for comparing the output signals of the high-frequency current sensor circuit, resonant filter circuit, and high-speed zero-crossing comparator circuit of the present invention;

[0059] Figure 5 a schematic diagram of a wireless charging system of the present invention;

[0060] Figure 6 Compared with Figure 5 a schematic diagram of a wireless charging system after the active rectification circuit changes;

[0061] Figure 7 Compared with Figure 5 another schematic diagram of a wireless charging system after the active rectification circuit changes. Specific Embodiments

[0062] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0064] Embodiment 1

[0065] An active rectification synchronization signal generation circuit, in a receiver of a wireless charging system, based on the output current of a resonant circuit, generates a phase synchronization signal required for an active rectification circuit, including:

[0066] a high-frequency current sensor circuit that measures the output current of the resonant circuit and converts it into a corresponding voltage signal; a resonant filter circuit that filters the voltage signal to obtain a processing result; a high-frequency zero-crossing comparator circuit that generates a phase synchronization signal through the processing result.

[0067] Figures 1 - 3As shown, in this embodiment, an active rectification synchronization signal generation circuit for a wireless charging system is provided, which can provide an accurate phase synchronization signal for the active rectification circuit of the wireless charging receiver, enabling the controller of the wireless charging receiver to obtain a stable phase reference for realizing synchronous rectification and phase shift control. During the implementation process, the oscillation problem of the active rectification circuit of the wireless charging receiver can be significantly improved, and the phase shift range and load range of the active rectification circuit can be effectively increased.

[0068] For the high-frequency current sensor circuit, the output current can be measured by a Hall current sensor. In this case, it is preferred that the bandwidth of the Hall current sensor is higher than the resonance frequency of the wireless charging system, so as to ensure that when the sensor measures the current, there will be no obvious error in the amplitude or phase of the signal due to bandwidth limitation, improving the overall measurement accuracy and stability of the system and supporting real-time dynamic adjustment; alternatively, the high-frequency current sensor circuit measures the output current through a current sampling resistor. Specifically, the Hall current sensor is suitable for scenarios that require electrical isolation, high safety, and adaptation to complex loads, especially performing excellently in high-frequency and high-voltage applications; the current sampling resistor is suitable for scenarios with higher requirements for cost, accuracy, and response speed, and at the same time allowing direct measurement of the circuit current; during the implementation process, which scheme to choose depends on specific application requirements and requirements for measurement accuracy, safety, cost, and bandwidth, and both methods are within the protection scope of the present invention.

[0069] Regardless of which form of the above high-frequency current sensor circuit is adopted, preferably, the high-frequency current sensor circuit further includes an operational amplifier to amplify or process the voltage signal to enhance the signal output ability. The main functions of the operational amplifier include increasing the signal amplitude, reducing signal distortion, and enhancing the anti-interference ability. In specific implementation, the operational amplifier can amplify the weak signal from the sensor to make it reach the level required by the subsequent circuit, ensuring the integrity and accuracy of signal transmission; at the same time, the operational amplifier can eliminate high-frequency noise and DC bias signals through the filtering function, thereby optimizing the signal quality; in addition, by carefully designing the feedback network, such as adjusting the feedback resistor, the gain can be flexibly controlled to meet the signal amplification requirements of different systems.

[0070] As a specific optimized implementation manner of the high-frequency current sensor circuit, refer to Figure 1 , the high-frequency current sensor circuit measures the output current of the resonance circuit and converts it into a corresponding voltage signal. The high-frequency current sensor circuit includes a Hall current sensor, a first input resistor, a first operational amplifier, and a first feedback resistor;

[0071] The input end of the Hall current sensor is connected to the output end of the resonant circuit; the first operational amplifier includes an inverting end and a non-inverting end, and the first input resistor is connected between the output end of the Hall current sensor and the inverting end; one end of the first feedback resistor is connected between the first input resistor and the inverting end, and the other end is connected to the output end of the first operational amplifier.

[0072] Based on the above circuit structure form, as a further optimization, the output voltage of the high-frequency current sensor circuit is calculated by the following formula:

[0073] ;

[0074] Wherein, V 3 is the output voltage of the high-frequency current sensor circuit, V 1 is the output voltage of the Hall current sensor, V 2 is the reference voltage input to the non-inverting end, R 2 is the resistance value of the first input resistor, R 3 is the resistance value of the first feedback resistor.

[0075] During the implementation process, it is only necessary to ensure that R 2 and R 3 have the same unit, V 1 , V 2 and V 3 have the same unit. In Figure 1 except for the above symbols, the R 1 shown is the resistance value of the output load of the Hall current sensor, i 1 is the output current of the resonant circuit, while U 1 is used to represent the first operational amplifier in this circuit.

[0076] In addition to the above optimization method, as another specific optimization implementation method of the high-frequency current sensor circuit, see Figure 2 , the high-frequency current sensor circuit includes a current sampling resistor, a second input resistor, a third input resistor, a fourth input resistor, a second operational amplifier, and a second feedback resistor;

[0077] The second operational amplifier includes an inverting terminal and a non-inverting terminal. The second input resistor is connected between one end of the current sampling resistor and the inverting terminal, and the third input resistor is connected between the other end of the current sampling resistor and the non-inverting terminal. One end of the second feedback resistor is connected between the second input resistor and the inverting terminal, and the other end is connected to the output terminal of the second operational amplifier. One end of the fourth input resistor is connected between the third input resistor and the non-inverting terminal, and the other end is connected to the input terminal of the reference voltage for the non-inverting terminal.

[0078] Based on the above circuit structure, as a further optimization, the output voltage of the high-frequency current sensor circuit is calculated using the following formula:

[0079] ;

[0080] Wherein, V 3 is the output voltage of the high-frequency current sensor circuit; V i+ and V i- are the voltages at the connection terminals of the current sampling resistor with the second input resistor and the third input resistor respectively; V 2 is the reference voltage input to the non-inverting terminal; R 4 is the resistance value of the second input resistor; R 5 is the resistance value of the third input resistor; R 6 is the resistance value of the second feedback resistor; R 7 is the resistance value of the fourth input resistor.

[0081] During the implementation process, it is only necessary to ensure that R 4 , R 5 , R 6 and R 7 have the same unit, V i+ , V i- , V 2 and V 3 have the same unit. In Figure 2 except for the above symbols, the R s is used to represent the current sampling resistor, U 3 is used to represent the second operational amplifier in this circuit, while i1 is the output current of the resonant circuit.

[0082] As an optimization method of the resonant filter circuit, as Figure 1 and 2 shown in, the resonant filter circuit includes a resistor, an inductor, and a capacitor;

[0083] The resistor is connected between the output terminal of the high-frequency current sensor circuit and the output terminal of the resonant filter circuit; the inductor and the capacitor form a parallel resonant circuit, one end of the parallel resonant circuit is connected to the output terminal of the resonant filter circuit, and the other end is connected to the negative pole of the power supply.

[0084] In the figure, V4 is the output voltage of the resonant filter circuit, and V5 is the output voltage of the high-frequency zero-crossing comparator circuit; in an ideal state, the resonant frequency of the parallel resonant circuit is the same as the resonant frequency of the wireless charging system, but in the actual implementation process, the signal output by the high-frequency current sensor circuit may have a lag. When the signal output by the high-frequency current sensor circuit lags, the resonant frequency of the parallel resonant circuit is adjusted to be higher than the resonant frequency of the wireless charging system to compensate for the delay caused by the high-frequency current sensor circuit, and the adjustment is achieved by adjusting the parameters of the inductor and the capacitor. In this preferred solution, the purpose of adjusting the resonant frequency of the parallel resonant circuit is to make the phase of the voltage output by the resonant filter circuit consistent with the fundamental wave component phase of the current input to the active rectifier circuit. At this time, the active rectifier circuit can achieve the maximum current utilization rate. The high-frequency current sensor circuit in the front stage of the resonant filter circuit usually has a delay due to bandwidth reasons, and the phase can be compensated by adjusting the resonant frequency of the parallel resonant circuit. Compared with the case of delay, phase compensation can reduce the demand for the output current of the resonant filter circuit when the output current is determined, thereby reducing losses and improving efficiency.

[0085] As a preference of the above embodiment, the parameter adjustment of the inductor and the capacitor is based on the following formula:

[0086] ;

[0087] wherein, f 0 is the resonant frequency of the parallel resonant circuit, with the unit of Hz; L f is the inductance value of the inductor, with the unit of H; C f is the capacitance value of the capacitor, with the unit of F.

[0088] In the specific implementation process, preferably, when the transmission gain of the resonant filter circuit changes beyond the set range, the resonant frequency of the parallel resonant circuit is adjusted, and the adjustment amplitude is related to the change amplitude of the transmission gain. Specifically, the adjustment amplitude and the change amplitude of the transmission gain are in a positive correlation relationship, that is, the greater the change in the transmission gain, the more serious the deviation of the resonant circuit from the optimal resonant frequency. Therefore, a larger amplitude of resonant frequency adjustment is required to re-match the resonant conditions and make up for the deviation.

[0089] Among them, the calculation formula for the transmission gain of the resonant filter circuit is as follows:

[0090] ;

[0091] ;

[0092] Among them, G(ω) is the transmission gain; ω is the angular frequency of the wireless charging system, with the unit of rad / s; ω 0 is the resonant angular frequency of the parallel resonant circuit, with the unit of rad / s; L f is the inductance value of the inductor, with the unit of H; R f is the resistance value of the resistor, with the unit of Ω; f is the resonant frequency of the wireless charging system.

[0093] As a preference of the above embodiment, as Figure 1 and 2 shown, the high-frequency zero-crossing comparator circuit includes a high-speed comparator, and the high-speed comparator includes a non-inverting terminal and an inverting terminal; the non-inverting terminal is connected to the output terminal of the resonant filter circuit, and the inverting terminal is connected to the negative pole of the power supply.

[0094] And as another implementation manner of the high-frequency zero-crossing comparator circuit, as Figure 3 shown, the high-frequency zero-crossing comparator circuit includes a high-speed comparator, and the high-speed comparator includes a non-inverting terminal and an inverting terminal; the inverting terminal is connected to the output terminal of the resonant filter circuit, and the non-inverting terminal is connected to the negative pole of the power supply.

[0095] As Figure 4As shown, a schematic diagram for comparing the output signals of a high-frequency current sensor circuit, a resonant filter circuit, and a high-frequency zero-crossing comparator circuit is provided; Signal 1 in the figure is a schematic diagram of the output signal waveform of the high-frequency current sensor circuit, and this signal waveform should be basically the same as the output current waveform of the resonant circuit of the wireless charging receiver; Signal 2 is a schematic diagram of the output signal waveform of the resonant filter circuit, and this signal waveform retains the fundamental wave component in the high-frequency current sensor circuit and filters out the harmonic components and DC components; Signal 3 is a schematic diagram of the output signal waveform of the high-speed zero-crossing comparator circuit, and this signal is at a high level when Signal 2 is greater than 0 and at a low level when Signal 2 is less than 0.

[0096] For the implementation effect, it is preferred that the transmission delay of the high-speed zero-crossing comparator is at the nanosecond level, so as to be able to support the precise processing of high-frequency signals, improve the phase synchronization accuracy, meet the high-frequency working requirements, and at the same time reduce the dynamic response problems caused by error accumulation and delay. These advantages together ensure the high efficiency and stable operation of the wireless charging system.

[0097] Embodiment 2

[0098] As a specific application mode of the active rectification synchronization signal generation circuit in Embodiment 1:

[0099] A receiver for a wireless charging system includes a resonant circuit and an active rectification circuit, and also includes the active rectification synchronization signal generation circuit as described in Embodiment 1; The active rectification synchronization signal generation circuit generates the required phase synchronization signal for the active rectification circuit based on the output current of the resonant circuit.

[0100] The technical effects achieved in this embodiment are as described in Embodiment 1 above and will not be elaborated here. Specifically, as Figures 5 - 7 shown in, the resonant compensation circuit shown in the figure is a specific implementation form of the resonant circuit, and the phase synchronization signal generated by the active rectification synchronization signal generation circuit is sent to the active rectification circuit through the controller.

[0101] As a preference of this embodiment, three specific implementation modes are provided for the active rectification circuit in this embodiment:

[0102] Such as Figure 5As shown, the active rectifier circuit is a bridge rectifier circuit. Each half-bridge of the bridge rectifier circuit consists of two MOSFETs, such as MOSFETs S5 and S6 in one half-bridge of the circuit topology shown in the figure, and MOSFETs S7 and S8 in the other half-bridge. The circuit in this embodiment is a full-MOSFET circuit. The wireless charging system using this circuit is topologically symmetric between the primary and secondary sides, that is, it can achieve bidirectional power transmission. This full-bridge circuit can be used as the active rectifier circuit at the receiving end and can be used as an inverter circuit when the power is transmitted in the reverse direction. In addition, in the rectification mode, the full-MOSFET circuit can achieve full-cycle synchronous rectification, with lower losses compared to diode rectification, which is beneficial to achieving higher efficiency. This circuit form is applicable to scenarios such as electric vehicle V2G and V2X that require bidirectional power transmission.

[0103] As Figure 6 shown, the active rectifier circuit is a bridge rectifier circuit. The upper tubes of the bridge rectifier circuit are two diodes, and the lower tubes are two MOSFETs, such as diodes D1 and D2 in the upper tubes of the circuit topology shown in the figure, and MOSFETs S6 and S8 in the lower tubes. The circuit in this embodiment has the lowest control complexity. The MOSFETs can share the drive power supply, without considering the dead zone, and there is no risk of shoot-through of the bridge arm. This circuit form can be used in scenarios of small power and unidirectional energy transmission, such as wireless charging of portable electronic devices, electric bicycles, unmanned inspection vehicles, and drones.

[0104] As Figure 7 shown, the active rectifier circuit is a bridge rectifier circuit. One half-bridge of the bridge rectifier circuit consists of two MOSFETs, and the other half-bridge consists of two diodes, such as MOSFETs S5 and S6 in one half-bridge of the circuit topology shown in the figure, and diodes D1 and D2 in the other half-bridge. Compared with the circuit shown in Figure 6 shown, the conduction time of the upper and lower tubes in one cycle is half a cycle, and the heating of the upper and lower tubes is balanced. However, the drive dead zone of the MOAFET half-bridge needs to be considered to avoid shoot-through. The applicable scenarios of this circuit are the same as those of the circuit shown in Figure 6 shown, which are also scenarios of small power and unidirectional energy transmission.

[0105] After applying the synchronous signal generation circuit of the present invention, the above three active rectifier circuits can effectively eliminate the oscillation problem caused by modulation and broaden the load range for the stable operation of the wireless charging system.

[0106] Embodiment 3

[0107] The wireless charging system includes a transmitter and a receiver;

[0108] The receiver includes a resonant circuit and an active rectifier circuit, and further includes an active rectifier synchronization signal generation circuit as described in Embodiment 1; the active rectifier synchronization signal generation circuit generates the required phase synchronization signal for the active rectifier circuit based on the output current of the resonant circuit.

[0109] The technical effects achievable in this embodiment are the same as those described in Embodiment 1, and will not be elaborated here.

[0110] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. An active rectification synchronization signal generating circuit, characterized in that: In the receiver of the wireless charging system, the phase synchronization signal required by the active rectification circuit is generated based on the output current of the resonant circuit, including: A high-frequency current sensor circuit measures the output current of the resonant circuit and converts it into a corresponding voltage signal; A resonant filter circuit performs filtering processing on the voltage signal to obtain a processing result; A high-frequency zero-crossing comparator circuit generates the phase synchronization signal through the processing result; The resonant filter circuit includes a resistor, an inductor and a capacitor; The resistor is connected between the output end of the high-frequency current sensor circuit and the output end of the resonant filter circuit; The inductor and the capacitor form a parallel resonant circuit, one end of the parallel resonant circuit is connected to the output end of the resonant filter circuit, and the other end is connected to the negative electrode of the power supply; When the signal output by the high-frequency current sensor circuit lags behind, the resonant frequency of the parallel resonant circuit is adjusted to be higher than the resonant frequency of the wireless charging system to compensate for the delay caused by the high-frequency current sensor circuit, wherein the adjustment is achieved by adjusting the parameters of the inductor and the capacitor; When the transmission gain variation of the resonant filter circuit exceeds a set range, the resonant frequency of the parallel resonant circuit is adjusted, and the adjustment amplitude is related to the variation amplitude of the transmission gain.

2. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The high-frequency current sensor circuit measures the output current through a Hall current sensor.

3. The active rectification synchronization signal generating circuit according to claim 2, characterized in that: The bandwidth of the Hall current sensor is higher than the resonant frequency of the wireless charging system.

4. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The high-frequency current sensor circuit measures the output current through a current sampling resistor.

5. The active rectification synchronization signal generating circuit according to claim 2 or 4, characterized in that: The high-frequency current sensor circuit also includes an operational amplifier for amplifying or processing the voltage signal.

6. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The high-frequency current sensor circuit includes a Hall current sensor, a first input resistor, a first operational amplifier and a first feedback resistor; The input end of the Hall current sensor is connected to the output end of the resonant circuit; The first operational amplifier includes an inverting terminal and a non-inverting terminal, and the first input resistor is connected between the output terminal of the Hall current sensor and the inverting terminal; One end of the first feedback resistor is connected between the first input resistor and the inverting end, and the other end is connected to the output end of the first operational amplifier.

7. The active rectification synchronization signal generating circuit according to claim 6, characterized in that: The output voltage of the high-frequency current sensor circuit is calculated using the following formula: ； Among them, V3 is the output voltage of the high-frequency current sensor circuit, V1 is the output voltage of the Hall current sensor, V2 is the reference voltage input to the in-phase terminal, R2 is the resistance value of the first input resistor, and R3 is the resistance value of the first feedback resistor.

8. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The high-frequency current sensor circuit includes a current sampling resistor, a second input resistor, a third input resistor, a fourth input resistor, a second operational amplifier and a second feedback resistor; The second operational amplifier comprises an inverting terminal and a non-inverting terminal, the second input resistor is connected between one end of the current sampling resistor and the inverting terminal, and the third input resistor is connected between the other end of the current sampling resistor and the non-inverting terminal; One end of the second feedback resistor is connected between the second input resistor and the inverting end, and the other end is connected to the output end of the second operational amplifier; One end of the fourth input resistor is connected between the third input resistor and the in-phase end, and the other end is connected to the input end of the in-phase end reference voltage.

9. The active rectification synchronization signal generating circuit according to claim 8, characterized in that: The output voltage of the high-frequency current sensor circuit is calculated using the following formula: ； Wherein, V3 is the output voltage of the high-frequency current sensor circuit; V i+ and V i- are respectively the voltages at the connection ends of the current sampling resistor and the second input resistor and the third input resistor; V2 is the reference voltage input to the in-phase end; R4 is the resistance value of the second input resistor; R5 is the resistance value of the third input resistor; R6 is the resistance value of the second feedback resistor; and R7 is the resistance value of the fourth input resistor.

10. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The parameters of the inductor and capacitor are adjusted according to the following formula: ； Wherein, f0 is the resonant frequency of the parallel resonant circuit, in Hz; L f is the inductance value of the inductor, in H; C f is the capacitance value of the capacitor, in F.

11. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The transmission gain calculation formula of the resonant filter circuit is as follows: ； ； Wherein, G(ω) is the transmission gain; ω is the angular frequency of the wireless charging system, in rad / s; ω0 is the resonant angular frequency of the parallel resonant circuit, in rad / s; L f is the inductance value of the inductor, in H; R f is the resistance value of the resistor, in Ω; f is the resonant frequency of the wireless charging system.

12. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The high-frequency zero-crossing comparator circuit includes a high-speed comparator, and the high-speed comparator includes a non-inverting terminal and an inverting terminal; the non-inverting terminal is connected to the output terminal of the resonant filter circuit, and the inverting terminal is connected to the negative electrode of the power supply.

13. The active rectification synchronization signal generating circuit according to claim 1, characterized in that: The high-frequency zero-crossing comparator circuit includes a high-speed comparator, and the high-speed comparator includes a non-inverting terminal and an inverting terminal; the inverting terminal is connected to the output terminal of the resonant filter circuit, and the non-inverting terminal is connected to the negative electrode of the power supply.

14. The active rectification synchronization signal generating circuit according to claim 12 or 13, characterized in that: The transmission delay of the high-speed comparator is in nanosecond order.

15. A receiver, characterized in that Used in a wireless charging system, comprising a resonant circuit and an active rectification circuit, and also comprising an active rectification synchronization signal generating circuit as claimed in any one of claims 1 to 14; The active rectification synchronization signal generating circuit generates a required phase synchronization signal for the active rectification circuit based on the output current of the resonance circuit.

16. The receiver according to claim 15, characterized in that The active rectifier circuit is a bridge rectifier circuit, and each half bridge of the bridge rectifier circuit comprises two MOSFETs.

17. The receiver according to claim 15, characterized in that The active rectifier circuit is a bridge rectifier circuit, the upper tube of the bridge rectifier circuit is two diodes, and the lower tube is two MOSFETs.

18. The receiver according to claim 15, characterized in that The active rectifier circuit is a bridge rectifier circuit, one half-bridge of the bridge rectifier circuit is two MOSFETs, and the other half-bridge is two diodes.

19. A wireless charging system, characterized in that: Includes a transmitter and a receiver; The receiver includes a resonant circuit and an active rectification circuit, and also includes an active rectification synchronization signal generating circuit as described in any one of claims 1 to 14; The active rectification synchronization signal generating circuit generates a required phase synchronization signal for the active rectification circuit based on the output current of the resonance circuit.

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