Active rectification synchronizing signal generating circuit, receiver and wireless charging system

Abstract

The invention relates to the technical field of wireless charging, in particular to an active rectification synchronizing signal generating circuit, a receiver and a wireless charging system.The active rectification synchronizing signal generating circuit generates a phase synchronizing signal needed by an active rectification circuit in the receiver of the wireless charging system based on the output current of a resonance circuit, and outputs the phase synchronizing signal to the receiver. Comprising a high-frequency current sensor circuit for measuring the output current of a resonance circuit and converting the output current into a corresponding voltage signal; the resonant filter circuit is used for filtering the voltage signal to obtain a processing result; and the high-frequency zero-crossing comparator circuit is used for generating a phase synchronizing signal according to a processing result. According to the invention, an accurate phase synchronization signal can be provided for the active rectification circuit of the wireless charging receiver so as to realize synchronous rectification and phase shift control, the oscillation problem of the active rectification circuit of the wireless charging receiver can be obviously improved in the implementation process, and the phase shift range and the load range of the active rectification circuit are effectively improved.

Description

Technical Field

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

[0002] As a contactless charging method, wireless charging technology can be applied in electric vehicles, automatic guided vehicles, smart phones and other scenarios. The wireless charging system is divided into two parts: the transmitter and the receiver, in which the receiver needs to rectify the high-frequency current.

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

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

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

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

[0007] The active rectification synchronization signal generating circuit generates the phase synchronization signal required by the active rectification circuit based on the output current of the resonant circuit in the receiver of the wireless charging system, including:

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

[0009] A resonant filter circuit performs filtering processing on the voltage signal to obtain a processing result;

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

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

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

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

[0014] Furthermore, the high-frequency current sensor circuit also 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 resonant 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 terminal 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 end, and the other end is connected to the output end of the first operational amplifier.

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

[0020] ;

[0021] 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.

[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 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;

[0024] 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;

[0025] 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.

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

[0027] ;

[0028] 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.

[0029] Further, the resonant filter circuit includes a resistor, an inductor and a capacitor;

[0030] The resistor is connected between the output end of the high-frequency current sensor circuit and the output end of the resonant filter circuit;

[0031] 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.

[0032] Furthermore, when the signal output by the high-frequency current sensor circuit is delayed, 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.

[0033] Furthermore, the parameters of the inductor and capacitor are adjusted according to the following formula:

[0034] ;

[0035] 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.

[0036] Furthermore, 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.

[0037] Furthermore, the transmission gain calculation formula 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, 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.

[0041] Furthermore, 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] Furthermore, 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] Furthermore, the transmission delay of the high-speed zero-crossing comparator is in nanosecond order.

[0044] A receiver for a wireless charging system, comprising a resonant circuit and an active rectification circuit, and also comprising an active rectification synchronization signal generating circuit as described above;

[0045] 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.

[0046] Furthermore, the active rectifier circuit is a bridge rectifier circuit, and each half bridge of the bridge rectifier circuit has two MOSFETs.

[0047] Furthermore, 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.

[0048] Furthermore, 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.

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

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

[0051] 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.

[0052] The technical solution of the present invention can achieve the following technical effects:

[0053] The present invention provides an active rectification synchronization signal generating circuit for a wireless charging system, which can provide an accurate phase synchronization signal for the active rectification circuit of a wireless charging receiver, so as to realize 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 improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 A schematic diagram of an active rectification synchronization signal generating circuit of the present invention;

[0056] Figure 2 For Figure 1 Compared with the high-frequency current sensor circuit, the schematic diagram of the active rectification synchronization signal generation circuit after the change;

[0057] Figure 3 For Figure 1 and Figure 2 Compared with the local part of FIG. 1 , the local schematic diagram of the active rectification synchronization signal generating circuit after the high-frequency zero-crossing comparator circuit changes;

[0058] Figure 4 It is a schematic diagram of output signal comparison of the high-frequency current sensor circuit, the resonant filter circuit, and the 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 For Figure 5 Compared with the above, a schematic diagram of a wireless charging system after the active rectifier circuit is changed;

[0061] Figure 7 For Figure 5 In comparison, another schematic diagram of a wireless charging system after the active rectification circuit is changed. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only 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 those commonly understood by those skilled in the art of the present invention. 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 related listed items.

[0064] Embodiment 1

[0065] The active rectification synchronization signal generating circuit generates the phase synchronization signal required by the active rectification circuit based on the output current of the resonant circuit in the receiver of the wireless charging system, including:

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

[0067] Figures 1 to 3 As shown, in this embodiment, an active rectification synchronization signal generating 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, so that the controller of the wireless charging receiver obtains a stable phase reference, so as to realize 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 improved.

[0068] For high-frequency current sensor circuits, the output current can be measured by a Hall current sensor. In this way, the bandwidth of the Hall current sensor is preferably higher than the resonant frequency of the wireless charging system, so as to ensure that when the sensor measures the current, there will be no significant error in the amplitude or phase of the signal due to bandwidth limitation, thereby improving the overall measurement accuracy and stability of the system, while 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 adaptability to complex loads, especially in high-frequency and high-voltage applications; the current sampling resistor is suitable for scenarios that have higher requirements for cost, accuracy, and response speed, while allowing direct measurement of circuit current; in the implementation process, which solution to choose depends on the specific application requirements and the requirements for measurement accuracy, safety, cost, and bandwidth, when both methods are within the scope of protection of the present invention.

[0069] Regardless of the form of the high-frequency current sensor circuit, preferably, the high-frequency current sensor circuit also includes an operational amplifier to amplify or process the voltage signal to enhance the signal output capability. The main functions of the operational amplifier include increasing the signal amplitude, reducing signal distortion, and enhancing anti-interference capability. In a specific implementation, the operational amplifier can amplify the weak signal from the sensor to reach the level required by the subsequent circuit to ensure the integrity and accuracy of signal transmission; at the same time, the operational amplifier can eliminate high-frequency noise and DC bias signals through filtering functions, thereby optimizing 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 of the high-frequency current sensor circuit, see Figure 1 The high-frequency current sensor circuit measures the output current of the resonant 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 and the inverting end of the Hall current sensor; 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, as a further optimization, the output voltage of the high-frequency current sensor circuit is calculated using the following formula:

[0073] ;

[0074] 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.

[0075] In the implementation process, it is only necessary to ensure that the units of R2 and R3 are the same, and the units of V1, V2 and V3 are the same. Figure 1 In addition to the above symbols, R1 is the resistance of the output load of the Hall current sensor, i1 is the output current of the resonant circuit, and U1 is used to represent the first operational amplifier in the 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 non-inverting terminal reference voltage.

[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, V3 is the output voltage of the high-frequency current sensor circuit; V i+ and V i- are the voltages at the connection ends of the current sampling resistor and the second input resistor and the third input resistor respectively; V2 is the reference voltage input to the in-phase terminal; 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.

[0081] In the implementation process, it is only necessary to ensure that the units of R4, R5, R6 and R7 are the same, V i+ 、V i- , V2 and V3 can be the same. Figure 2 In addition to the above symbols, the R s It is used to represent the current sampling resistor, U3 is used to represent the second operational amplifier in the circuit, and i1 is the output current of the resonant circuit.

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

[0083] 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 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 consistent with 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 be delayed. When the signal output by the high-frequency current sensor circuit is delayed, 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. The adjustment is achieved by adjusting the parameters of the inductor and the capacitor. In this preferred embodiment, the purpose of adjusting the resonant frequency of the parallel resonant circuit is to make the voltage phase output by the resonant filter circuit consistent with the fundamental component phase of the current input to the active rectifier circuit, and the active rectifier circuit can achieve the maximum current utilization. The high-frequency current sensor circuit at the front stage of the resonant filter circuit usually has a delay due to bandwidth reasons, and the phase can be compensated back 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 preferred embodiment of the above embodiment, the parameters of the inductor and the capacitor are adjusted according to the following formula:

[0086] ;

[0087] Where 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.

[0088] In the specific implementation process, preferably, when the transmission gain change of the resonant filter circuit exceeds 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 is positively correlated with the change amplitude of the transmission gain, that is, the greater the change in the transmission gain, the more serious the degree of deviation of the resonant circuit from the optimal resonant frequency, and therefore, a larger amplitude of resonant frequency adjustment is required to re-match the resonant condition and compensate for the deviation.

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

[0090] ;

[0091] ;

[0092] Where 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 fis 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.

[0093] As a preferred embodiment of the above, Figure 1 and 2 As 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 electrode of the power supply.

[0094] As another implementation of the high-frequency zero-crossing comparator circuit, Figure 3 As shown, the high-frequency zero-crossing comparator circuit includes a high-speed comparator, which 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.

[0095] like Figure 4 As shown, a schematic diagram of the output signal comparison of the high-frequency current sensor circuit, the resonant filter circuit and the 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 the signal waveform should be basically consistent with the output current waveform of the wireless charging receiver resonant circuit; signal 2 is a schematic diagram of the output signal waveform of the resonant filter circuit, and the signal waveform retains the fundamental component in the high-frequency current sensor circuit and filters the harmonic component and the DC component; signal 3 is a schematic diagram of the output signal waveform of the high-speed zero-crossing comparator circuit, and the signal is high when signal 2 is greater than 0, and is low when signal 2 is less than 0.

[0096] For the purpose of implementation, the transmission delay of the high-speed zero-crossing comparator is preferably in the nanosecond level, so as to support the accurate processing of high-frequency signals, improve the phase synchronization accuracy, adapt to the high-frequency working requirements, and 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 of the active rectification synchronization signal generating circuit in the first embodiment:

[0099] A receiver, used in a wireless charging system, comprises a resonant circuit and an active rectifier circuit, and also comprises an active rectifier synchronization signal generating circuit as described in the first embodiment; the active rectifier synchronization signal generating circuit generates a required phase synchronization signal for the active rectifier circuit based on an output current of the resonant circuit.

[0100] The technical effects achieved by this embodiment are as described in the above embodiment 1, and will not be repeated here. Figures 5 to 7As shown in the figure, 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 generating circuit is sent to the active rectification circuit through the controller.

[0101] As a preferred embodiment of this embodiment, this embodiment provides three specific implementation methods for the active rectifier circuit:

[0102] like Figure 5 As shown, the active rectifier circuit is a bridge rectifier circuit, and each half-bridge of the bridge rectifier circuit is two MOSFETs, such as MOSFETs S5 and S6 in one half-bridge of the circuit topology, and MOSFETs S7 and S8 in the other half-bridge. The circuit in this embodiment is a full MOSFET circuit, and the wireless charging system using this circuit is topologically symmetrical between the primary and secondary sides, that is, it can achieve bidirectional power transmission. The full-bridge circuit can be used as an active rectifier circuit at the receiving end, and can be used as an inverter circuit when the power is transmitted in reverse; in addition, in the rectification mode, the full MOSFET circuit can achieve full-cycle synchronous rectification, which has lower losses than diode rectification, and is conducive to achieving higher efficiency. This circuit form is suitable for scenarios such as electric vehicles V2G and V2X that require bidirectional power transmission.

[0103] like Figure 6 As shown, 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, such as the diodes D1 and D2 in the upper tube of the circuit topology, and the MOSFETS6 and S8 in the lower tube. The circuit control complexity in this embodiment is the lowest, the MOSFET can share the driving power supply, there is no need to consider the dead zone, and there is no risk of bridge arm direct connection. This circuit form can be used in scenarios with low power and unidirectional energy transmission, such as wireless charging of portable electronic devices, electric bicycles, unmanned inspection vehicles, drones and other equipment.

[0104] like Figure 7 As shown, 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, 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. The circuit in this embodiment is similar to Figure 6 Compared with the circuit shown in the figure, the conduction time of the upper and lower tubes in one cycle is half a cycle, and the heat generation of the upper and lower tubes is balanced, but the driving dead zone of the MOAFET half-bridge needs to be considered to avoid direct conduction. Figure 6 The circuit shown is consistent, and it is also a scenario of low power and unidirectional energy transmission.

[0105] The above three active rectification circuits can effectively eliminate the oscillation problem caused by modulation after applying the synchronization signal generating circuit of the present invention, and broaden the load range of stable operation of the wireless charging system.

[0106] Embodiment 3

[0107] A wireless charging system including a transmitter and a receiver;

[0108] The receiver includes a resonant circuit and an active rectifier circuit, and also includes an active rectifier synchronization signal generating circuit as described in Example 1; the active rectifier synchronization signal generating 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 that can be achieved by this embodiment are the same as those described in Embodiment 1 and will not be repeated here.

[0110] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached 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.

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 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.

11. The active rectification synchronization signal generating circuit according to claim 10, characterized in that: When the signal output by the high-frequency current sensor circuit is delayed, 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.

12. The active rectification synchronization signal generating circuit according to claim 11, 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.

13. The active rectification synchronization signal generating circuit according to claim 11, characterized in that: 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.

14. The active rectification synchronization signal generating circuit according to claim 13, 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.

15. 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.

16. 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.

17. The active rectification synchronization signal generating circuit according to claim 15 or 16, characterized in that: The transmission delay of the high-speed zero-crossing comparator is in nanosecond order.

18. 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 17; 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.

19. The receiver according to claim 18, characterized in that The active rectifier circuit is a bridge rectifier circuit, and each half bridge of the bridge rectifier circuit comprises two MOSFETs.

20. The receiver according to claim 18, 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.

21. The receiver according to claim 18, 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.

22. 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 17; 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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