Receiver and amplitude shift keying modulation method

Abstract

The invention provides a receiver and an amplitude shift keying modulation method, and the receiver comprises a resonant cavity which comprises a receiver coil and a resonant capacitor which are connected in series, and the receiver coil is used for forming wireless power transmission with a transmitter coil of a transmitter in a wireless power transmission system; the rectifying circuit comprises at least one switching tube, the first input end and the second input end of the rectifying circuit are connected with the two ends of the resonant cavity respectively, the output end of the rectifying circuit is used for being connected with a load, and an amplitude shift keying modulation mode is adopted when the receiver transmits signals to the transmitter; the controller is used for controlling the switch-on and switch-off of a switch tube in the rectification circuit in a synchronous rectification control mode, and controlling the switch tube in the rectification circuit when amplitude shift keying modulation is carried out; therefore, a phase difference exists between the voltage of the first input end or the second input end of the rectifying circuit and the resonant current in the resonant cavity.

Description

Technical Field

[0001] This application relates to wireless power transfer, especially receivers and amplitude shift keying modulation methods. Background Art

[0002] With the development of technology, wireless power transfer has become an efficient and convenient mechanism for powering or charging battery-based mobile devices (such as mobile phones, tablet computers, digital cameras, and similar devices).

[0003] Please refer to Figure 1 the schematic diagram of a typical wireless power transfer system shown. The wireless power transfer system includes a transmitter 100 and a receiver 200. The transmitter 100 includes an inverter circuit 110 and a transmitter-side resonator 130 connected in cascade. The transmitter-side resonator 130 includes a transmitter coil L1 and a transmitter-side resonant capacitor C1 connected in series. The receiver 200 includes a receiver-side resonator 230 and a rectifier circuit 210 connected in cascade. The receiver-side resonator 230 includes a receiver coil L2 and a receiver-side resonant capacitor C2 connected in series.

[0004] When the receiver 200 is placed within the output power range of the transmitter 100, magnetic coupling is established between the transmitter coil L1 and the receiver coil L2, and the output power of the transmitter 100 is transmitted to the receiver 200, that is, wireless power transfer is formed between the transmitter 100 and the receiver 200 to charge a load (such as a rechargeable battery and / or battery pack in a mobile device).

[0005] Please refer to again Figure 1 , the transmitter 100 further includes a demodulation device 120, and the receiver 200 further includes a modulation device 220. The demodulation device 120 and the modulation device 220 form a communication device to perform wireless communication between the receiver 200 and the transmitter 100.

[0006] Specifically, the control signal for controlling the operation of the inverter circuit 110 is generated according to the operating parameters transmitted from the receiver 200. In practical applications, signals are usually transmitted between the transmitter 100 and the receiver 200 in the form of a modulation signal, where amplitude shift keying (ASK) is a widely used modulation scheme in wireless power transfer systems.

[0007] ASK is performed by modulating the amplitude of the analog signal in the wireless power transfer system, where Figure 1 the modulation device 220 in is used as an ASK modulator, and the demodulation device 120 is used as an ASK demodulator. The ASK demodulator detects the signal of the ASK modulator and obtains the communication signal by demodulating the state change of the ASK modulator. The inverter circuit 110 generates a control signal for controlling the operation of the inverter circuit 110 according to this communication signal.

[0008] One commonly used ASK modulation method is capacitance modulation. For details, please refer to Figure 2 the schematic diagram of the main circuit of the wireless power transmission system using capacitance modulation in the prior art shown in the figure. Three groups of capacitor switch series branches are symmetrically connected between both ends of the rectifier circuit 210 and the receiver-side resonator 230. By controlling the on and off of the switching tubes therein, the capacitors are cut in and out, and the gain of the receiver-side resonator 230 is changed to achieve the encoding of ASK modulation and realize ASK modulation. The capacitors therein can be called communication capacitors, and the switches are called modulation switches.

[0009] Figure 2 Three groups of capacitor switch series branches are shown in the figure. In practical applications, there can also be two groups. The capacitance modulation method has the advantage of high signal strength. However, since the capacitance value of the capacitor is generally between 10 nF and 47 nF, the capacitor cannot be integrated into the receiver chip like the switching tube and can only be placed outside the chip and connected to the pins of the chip, which results in low integration of the receiver. In addition, the number of pins of the receiver chip is limited by the chip size. Currently, the common receiver chips only support 2 groups, at most 3 groups of communication capacitors and modulation switches, which results in the limitation of capacitance modulation by the number of groups of communication capacitors and modulation switches.

[0010] Another commonly used ASK modulation method is load current modulation, which realizes the encoding of ASK modulation by changing the magnitude of the load current. The modulation of the load current is usually realized through semiconductor devices, so it can be integrated into the chip, has the advantage of high integration, and can also achieve multi-gear and multi-gradient modulation compared with capacitance modulation. However, the load current modulation method will increase the loss of the receiver chip. The greater the output voltage and the same magnitude of the load current, the greater the loss. The load current debugging method will also cause the output voltage to drop. If the subsequent stage of the receiver is a charge pump or a buck circuit, there are restrictions on the sinking of the receiver output voltage, which will result in restrictions on the packet sending intensity. And the load current modulation also has the disadvantage of low signal strength. Summary of the Invention

[0011] According to an embodiment, the present application provides a receiver applied to a wireless power transfer system, including: a resonant cavity including a receiver coil and a resonant capacitor connected in series, where the receiver coil is configured to form wireless power transfer with a transmitter coil of a transmitter in the wireless power transfer system; a rectifier circuit including at least one switching tube, where a first input terminal and a second input terminal of the rectifier circuit are respectively connected to two ends of the resonant cavity, and an output terminal of the rectifier circuit is configured to be connected to a load, and where the receiver uses amplitude shift keying modulation when transmitting a signal to the transmitter; a controller configured to control conduction and cutoff of the switching tube in the rectifier circuit in a synchronous rectification control manner, and where, when performing amplitude shift keying modulation, the switching tube in the rectifier circuit is controlled such that there is a phase difference between a voltage at the first input terminal or the second input terminal of the rectifier circuit and a resonant current in the resonant cavity.

[0012] Further, when performing amplitude shift keying modulation, the controller is configured to control a cutoff moment of a switching tube in the rectifier circuit such that there is a phase difference between a voltage at the first input terminal or the second input terminal of the rectifier circuit and the resonant current.

[0013] Further, when performing amplitude shift keying modulation, the controller is configured to control a cutoff moment of a switching tube in the rectifier circuit such that a voltage phase at the first input terminal of the rectifier circuit lags behind or leads ahead of a resonant current phase, or a voltage phase at the second input terminal of the rectifier circuit lags behind or leads ahead of the resonant current phase.

[0014] Further, the controller is configured to: obtain a current flowing through a switching tube in the rectifier circuit or a voltage across the switching tube; and when the current or the voltage reaches a cutoff threshold, control the switching tube to cutoff.

[0015] Further, the cutoff threshold is greater than zero.

[0016] Further, the cutoff threshold is stored in a storage unit in the controller.

[0017] Further, during amplitude shift keying modulation, the controller is configured to change the cutoff threshold through the storage unit to change a cutoff moment of the switching tube in the rectifier circuit.

[0018] According to one embodiment, the present application further provides an amplitude shift keying modulation method for a wireless power transfer system, wherein the receiver in the wireless power transfer system includes a cascaded resonator and a rectifier circuit, and a controller. The rectifier circuit includes at least one switching tube, and the controller is configured to control the conduction and turn-off of the switching tube in the rectifier circuit in a synchronous rectification control manner, including: the controller obtains the current flowing through a switching tube in the rectifier circuit or the voltage across the switching tube; when the current or the voltage reaches a turn-off threshold, the controller controls the switching tube to turn off, where the turn-off threshold is greater than zero.

[0019] Furthermore, it further includes: setting the turn-off threshold such that there is a phase difference between the voltage at one end of the rectifier circuit connected to the resonator and the resonant current in the resonator.

[0020] Furthermore, the turn-off threshold is stored in a storage unit within the controller.

[0021] Furthermore, during amplitude shift keying modulation, the turn-off threshold is changed to change the turn-off moment of the switching tube in the rectifier circuit.

[0022] The features and technical advantages of the present disclosure have been outlined quite extensively above so that the following detailed description of the disclosure can be better understood. The following will describe additional features and advantages of the present disclosure, which form the subject matter of the claims of the present disclosure. Those skilled in the art should understand that the disclosed concepts and specific embodiments can be easily used as a basis for modifying or designing other structures or processes for achieving the same purpose of the present disclosure. Those skilled in the art should also recognize that such equivalent structures do not depart from the spirit and scope of the present disclosure as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To more fully understand the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0024] Figure 1 Shows a schematic diagram of a typical wireless power transfer system;

[0025] Figure 2 Shows a schematic diagram of the main circuit of a wireless power transfer system using capacitance modulation in the prior art;

[0026] Figure 3 Shows a schematic diagram of a typical receiver main circuit;

[0027] Figure 4 Shows a carrier signal diagram of the voltage V1 at the first input terminal of the rectifier circuit in a receiver in the prior art and the resonant current IR in the resonator;

[0028] Figure 5Shows a schematic diagram of a receiver according to an embodiment of the present application;

[0029] Figure 6 Shows a schematic diagram of the internal block diagram of a controller according to an embodiment of the present application;

[0030] Figure 7 Shows a schematic diagram of the waveforms of the voltage V1 at the first input terminal of the rectifier circuit and the resonant current IR in the resonant cavity during one switching cycle according to an embodiment of the present application;

[0031] Figure 8 Shows a schematic diagram of the waveforms of the voltage V1 at the first input terminal of the rectifier circuit and the resonant current IR in the resonant cavity during one switching cycle according to another embodiment of the present application;

[0032] Figure 9 Shows a schematic diagram of the test eye diagram waveform when amplitude shift keying modulation of the present application is adopted;

[0033] Figure 10 Shows a schematic diagram of the internal block diagram of a controller according to another embodiment of the present application;

[0034] Figure 11 Shows a schematic diagram of the waveforms of the voltage V1 at the first input terminal of the rectifier circuit and the resonant current IR in the resonant cavity during one switching cycle according to another embodiment of the present application;

[0035] Figure 12 Shows a schematic diagram of the flow of the amplitude shift keying modulation method of a wireless power transmission system according to an embodiment of the present application.

[0036] Unless otherwise specified, corresponding numbers and symbols in different drawings generally refer to corresponding parts. These drawings are drawn to clearly illustrate relevant aspects of various embodiments and are not necessarily drawn to scale. Detailed implementation manners

[0037] Next, the technical solutions in the present application will be described clearly and completely in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0038] In practical applications, the rectifier circuit includes at least one switching tube, and the rectification function is realized by controlling the on and off of the switching tube. Usually, a diode is connected in parallel at both ends of the switching tube, and the diode can be the body diode of the switching tube or a separate diode.

[0039] Please refer to Figure 3A schematic diagram of the main circuit of a receiver is shown. The rectifier circuit 210 therein is a typical full-bridge rectifier circuit, including a first bridge arm formed by series connection of a first switching tube Q1 and a third switching tube Q3, a second bridge arm formed by series connection of a second switching tube Q2 and a fourth switching tube Q4, and the first bridge arm and the second bridge arm are connected in parallel. Among them, the common node of the first switching tube Q1 and the third switching tube Q3 is the first input end AC1 of the rectifier circuit, the common node of the second switching tube Q2 and the fourth switching tube Q4 is the second input end AC2 of the rectifier circuit, and the first input end AC1 and the second input end AC2 are respectively connected to both ends of the receiver-side resonator 230. The receiver-side resonator 230 includes a receiver coil L2 and a receiver-side resonant capacitor C2 connected in series. Both ends of the first bridge arm and the second bridge arm connected in parallel can form the output end of the receiver for connecting a load and supplying power to the load.

[0040] In practical applications, in order to improve the efficiency of the rectifier circuit, the on and off of the switching tubes in the rectifier circuit are controlled in a synchronous rectification control manner. Specifically, when the resonant current IR commutes, once it is detected that the current flowing through the conducting switching tube decreases to or the voltage drop across its two ends decreases to near zero, the conducting switching tube is controlled to turn off, or once it is detected that there is current flowing through the diode in parallel with the switching tube to be operated or there is a voltage drop across the switching tube, the switching tube to be operated is controlled to turn on, that is, when the resonant current IR passes through the zero point, the conducting switching tube is controlled to turn off and the switching tube to be operated is controlled to turn on, so as to realize the switching of the on or off of the switching tube, so as to realize the synchronous commutation between the voltage of the first input end AC1 or the second input end AC2 of the rectifier circuit and the resonant current IR in the resonator. We know that the voltage drop generated by the equivalent impedance of the switching tube (such as MOS tube) is very small, so the loss is small, and the efficiency can be improved, especially prominent under large current.

[0041] Since in each switching cycle, the voltage of the first input end AC1 or the second input end AC2 of the rectifier circuit and the resonant current IR in the resonator are synchronously commutated, their carrier signals are also synchronously commutated. Please refer to Figure 4 as shown in Figure 3 the schematic diagram of the carrier signals of the voltage of the first input end of the rectifier circuit in the receiver in

[0042] For Figure 2 the wireless power transmission system adopting capacitance modulation shown, when the communication capacitor is connected, the commutation of the voltage of the first input end AC1 or the second input end AC2 of the rectifier circuit will lag behind the resonant current IR in the resonator. As Figure 4The line labeled V1 as shown represents the carrier signal of the voltage at the first input terminal AC1 when a communication capacitor with a certain capacitance value is connected. It can be seen that it rises slowly when the resonant current IR commutes, which is equivalent to having a phase lagging behind the resonant current IR, thereby causing the gain of the resonant cavity 230 on the receiver side to change and enabling ASK modulation.

[0043] In actual implementation, the value of the connected communication capacitor can be controlled by controlling the modulation switch, thereby adjusting the phase of the voltage at the first input terminal AC1 or the second input terminal AC2 lagging behind the resonant current IR, and adjusting the gain of the resonant cavity 230 on the receiver side.

[0044] As above, Figure 2 Although the wireless power transmission system as shown can implement the ASK modulation method, since the communication capacitor cannot be integrated into the receiver chip, the integration degree of the receiver is low. In addition, the number of pins of the receiver chip is limited by the chip size, resulting in capacitance modulation being limited by the communication capacitor and the number of groups of modulation switches.

[0045] In an embodiment of the present application, it is to provide a receiver applied to a wireless power transmission system. Specifically, please refer to Figure 5 the schematic diagram of the receiver according to an embodiment of the present application as shown, and please combine with Figure 1 , the receiver includes:

[0046] A resonant cavity 230, including a receiver coil L2 and a resonant capacitor C2 connected in series. The receiver coil L2 is used to form wireless power transmission with the transmitter coil of the transmitter in the wireless power transmission system;

[0047] A rectifier circuit 210, including at least one switching tube. The first input terminal AC1 and the second input terminal AC2 of the rectifier circuit are respectively connected to both ends of the resonant cavity 230. The output terminal of the rectifier circuit 210 is used to connect to a load, and the receiver uses amplitude shift keying modulation when transmitting signals to the transmitter;

[0048] A controller 240, used to control the on and off of the switching tube in the rectifier circuit 210 in a synchronous rectification control manner. When performing amplitude shift keying modulation, the switching tube in the rectifier circuit 210 is controlled so that there is a phase difference between the voltage at the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit 210 and the resonant current IR in the resonant cavity 230.

[0049] That is, when performing amplitude shift keying modulation, the present application controls the switching tube in the rectifier circuit 210 through the controller 240 so that there is a phase difference between the voltage at the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit 210 and the resonant current IR in the resonant cavity 230, which is similar to Figure 2 the capacitance modulation as shown, and has a phase difference, and its effect is equivalent toFigure 2 The relationship between V1 and IR in [reference] can adjust the gain of the resonant cavity 230 to achieve ASK modulation.

[0050] The controller 240 is an essential control unit of the receiver. Therefore, compared with Figure 3 the typical receiver shown in [reference], Figure 5 the receiver of the present application shown in [reference] realizes ASK modulation on the basis of maintaining the original high integration of the receiver, and there is no need to change the hardware, so the design is simple. In actual implementation, when performing amplitude shift keying modulation, the controller 240 controls the switching tube in the rectification circuit 210 to make there be a phase difference between the voltage of the first input terminal AC1 or the second input terminal AC2 of the rectification circuit and the resonant current IR in the resonant cavity, so as to achieve ASK modulation. During the normal power transmission process, the controller 240 controls the on and off of the switching tube in the rectification circuit 210 in the synchronous rectification control mode. Therefore, the receiver provided by the present application also has the advantage of high efficiency possessed by the synchronous rectification control mode.

[0051] Furthermore, compared with the traditional capacitance modulation, it does not need to occupy the chip pins of the controller 240, and there is no need to arrange capacitors outside the chip, so the integration of the receiver is improved.

[0052] Furthermore, compared with the traditional load current modulation, it does not need to change the magnitude of the load current, so there are no disadvantages such as the output voltage drop and large loss caused by the load current modulation.

[0053] In a specific embodiment, when performing amplitude shift keying modulation, the controller 240 is configured to control the turn-off moment of a switching tube in the rectification circuit 210 so that there is a phase difference between the voltage of the first input terminal AC1 or the second input terminal AC2 of the rectification circuit 210 and the resonant current IR.

[0054] The following will take Figure 5 the rectification circuit shown in [reference] including a full-bridge rectification unit composed of four switching tubes as an example to illustrate its working principle. For Figure 5 the full-bridge rectification unit shown in [reference], the first switching tube Q1 and the fourth switching tube Q4 are a pair of tubes, and their drive signals are the same, that is, the first switching tube Q1 and the fourth switching tube Q4 are turned on and off simultaneously; the second switching tube Q2 and the third switching tube Q3 are a pair of tubes, and their drive signals are the same, that is, the second switching tube Q2 and the third switching tube Q3 are turned on and off simultaneously; the first switching tube Q1 and the third switching tube Q3 work complementarily; the second switching tube Q2 and the fourth switching tube Q4 work complementarily. Then for Figure 5 the full-bridge rectification unit shown in [reference], the controller 240 can obtain the control signals of other switching tubes according to the control signal of one of the switching tubes.

[0055] Specifically, for a rectifier circuit operating in a synchronous rectification control mode, the controller 240 obtains the current flowing through at least one switching device in the rectifier circuit or the voltage across its two ends as a sampling signal, and obtains a switching control signal for controlling the operation of the switching devices in the rectifier circuit according to the sampling signal. As Figure 5 shown, in one embodiment, a sampling signal representing the electrical signal of the third switching device Q3 as the lower transistor is obtained, and a switching control signal for controlling the first switching device Q1 to the fourth switching device Q4 is obtained according to the sampling signal. The following will illustrate the principle by taking the phase relationship between the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 and the resonant current IR as an example.

[0056] Specifically, please refer to Figure 6 the schematic diagram of the internal block diagram of the controller according to an embodiment of the present application shown in the figure. The controller 240 includes a comparator 241, a storage unit 242, a subtractor 243, and a control signal generation unit 244. The positive input terminal of the subtractor 243 is connected to the first terminal of the third switching device Q3, and the negative input terminal of the subtractor 243 is connected to the storage unit 242 to receive the voltage reference signal Vref output by the storage unit 242. The output terminal of the subtractor 243 is connected to the positive input terminal of the comparator 241. The negative input terminal of the comparator 241 is connected to the second terminal of the third switching device Q3. The output terminal of the comparator 241 is connected to the control signal generation unit 244. The control signal generation unit 244 outputs a control signal for controlling the third switching device Q3 according to the output result of the comparator 241. In this way, the control signal generation unit 244 generates a control signal for controlling the third switching device Q3 according to the comparison result between the voltage sampling signal across the two ends of the third switching device Q3 and the voltage reference signal Vref.

[0057] As Figure 6 shown, taking the third switching device Q3 as a MOSFET as an example, the first terminal of the third switching device Q3 is the drain, and the second terminal of the third switching device Q3 is the source. In practical applications, the specific type of the switching device is not limited.

[0058] In traditional synchronous rectification control, when the resonant current IR changes from a negative value to a positive value, once it is detected that the voltage across the two ends of the third switching device Q3 drops to zero, the output signal of the comparator 241 is inverted, which is equivalent to the voltage reference signal Vref being zero. The control signal of the third switching device Q3 is switched to a low level, and at the same time, the second switching device Q2 is synchronously turned off, and the first switching device Q1 and the fourth switching device Q4 that work complementarily are synchronously turned on. The voltage V1 at the first input terminal AC1 of the rectifier circuit 210 and the resonant current IR are in the same phase.

[0059] In this application, when performing amplitude shift keying (ASK) modulation, the controller 240 is configured to control the turn-off time of the switching transistors in the rectifier circuit so that it is not synchronized with the commutation of the resonant current IR, so that there is a phase difference between the voltage V1 at the first input terminal AC1 of the rectifier circuit and the resonant current IR, thereby realizing ASK modulation.

[0060] Specifically, please refer to Figure 7 the schematic diagram of the waveforms of the voltage V1 at the first input terminal of the rectifier circuit and the resonant current IR in the resonant cavity in one switching cycle of an embodiment of this application shown in Figure 5 and Figure 6 . Before the moment t1, the third switching transistor Q3 and the second switching transistor Q2 are turned on, then the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 is pulled to the ground and is zero, and the resonant current IR is negative (with the current direction in Figure 5 being positive) and changes in a similar sine wave. At the moment t1, the resonant current IR changes to zero, and the resonant current IR starts to commutate, that is, it changes from negative to positive. The voltage drops across the third switching transistor Q3 and the second switching transistor Q2 decrease to zero. At this time, unlike traditional synchronous rectification control where the control causes the third switching transistor Q3 and the second switching transistor Q2 to turn off, and the corresponding control causes the first switching transistor Q1 and the fourth switching transistor Q4 to turn on, instead, the control still causes the third switching transistor Q3 and the second switching transistor Q2 to remain turned on and the first switching transistor Q1 and the fourth switching transistor Q4 to remain turned off, that is, to control the turn-off time of the third switching transistor Q3 and the second switching transistor Q2 to delay the turn-off time of the third switching transistor Q3 and the second switching transistor Q2. Then the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 still remains zero, the current flowing through the third switching transistor Q3 and the second switching transistor Q2 reverses and gradually increases from zero. For example, when the third switching transistor Q3 and the second switching transistor Q2 are MOSFETs, the current flows from the drain to the source, and the voltage drop across them also gradually increases from zero, as shown in Figure 7When the voltage drop across the third switching transistor Q3 increases to (reaches) the first voltage threshold Vref1 provided by the storage unit 242, that is, at time t2, the third switching transistor Q3 and the second switching transistor Q2 are controlled to turn off. The corresponding control causes the first switching transistor Q1 and the fourth switching transistor Q4 to conduct. Then, the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 switches to positive only at time t2. In this way, a first phase difference θ1 is achieved between the voltage V1 at the first input terminal AC1 of the rectifier circuit and the resonant current IR. That is, at this time, a sampling signal representing the electrical signal of the third switching transistor Q3 as the lower transistor is obtained, and the switching control signals for controlling the first switching transistor Q1 to the fourth switching transistor Q4 are obtained according to this sampling signal. The sampling signal of the electrical signal of the second switching transistor Q2 corresponds to that of the third switching transistor Q3. Therefore, the switching control signals for controlling the first switching transistor Q1 to the fourth switching transistor Q4 can also be obtained by obtaining a sampling signal representing the electrical signal of the second switching transistor Q2 as the upper transistor and according to this sampling signal.

[0061] Continuing, when the resonant current IR changes from positive to negative for commutation at time t3, the voltage drops across the first switching transistor Q1 and the fourth switching transistor Q4 decrease to zero. At this time, unlike traditional synchronous rectification control where the first switching transistor Q1 and the fourth switching transistor Q4 are controlled to turn off and the third switching transistor Q3 and the second switching transistor Q2 are controlled to conduct correspondingly, the first switching transistor Q1 and the fourth switching transistor Q4 are still controlled to remain conducting, and the third switching transistor Q3 and the second switching transistor Q2 are still controlled to remain off. That is, the turn-off times of the first switching transistor Q1 and the fourth switching transistor Q4 are controlled to delay the turn-off times of the first switching transistor Q1 and the fourth switching transistor Q4. Then, the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 remains positive, and the current flowing through the first switching transistor Q1 and the fourth switching transistor Q4 reverses and gradually decreases from zero. For example, when the first switching transistor Q1 and the fourth switching transistor Q4 are MOSFETs, the current flows from the drain to the source, and the voltage drop across them also gradually increases from zero, as Figure 7When the voltage drop across the fourth switching transistor Q4 increases to (reaches) the first threshold Vref1, that is, at time t4, the first switching transistor Q1 and the fourth switching transistor Q4 are controlled to turn off, and the third switching transistor Q3 and the second switching transistor Q2 are controlled to turn on. Then, the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 becomes zero at time t4. In this way, a first phase difference θ1 is also present between the voltage V1 at the first input terminal AC1 of the rectifier circuit and the resonant current IR. That is, at this time, a sampling signal representing the electrical signal of the fourth switching transistor Q4 as the lower transistor is obtained, and based on this sampling signal, the switching control signals for controlling the first switching transistor Q1 to the fourth switching transistor Q4 are obtained. The sampling signal of the electrical signal of the first switching transistor Q1 corresponds to the fourth switching transistor Q4. Therefore, it is also possible to obtain a sampling signal representing the electrical signal of the first switching transistor Q1 as the upper transistor, and based on this sampling signal, the switching control signals for controlling the first switching transistor Q1 to the fourth switching transistor Q4 are obtained.

[0062] For the second input terminal AC2 of the rectifier circuit 210, when the voltage at the first input terminal AC1 of the rectifier circuit 210 is zero, the voltage at the second input terminal AC2 is positive, and when the voltage at the first input terminal AC1 of the rectifier circuit 210 is positive, the voltage at the second input terminal AC2 is zero. Therefore, there is also a phase difference between it and the resonant current IR, which will not be elaborated here.

[0063] For a carrier signal having a carrier frequency (such as 1 KHZ) that is relatively low compared to the switching frequency (such as 200 KHZ), there is also a phase difference between the voltage V1 at the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit and the resonant current IR, achieving the same function as capacitance modulation and realizing ASK modulation.

[0064] In practical applications, different thresholds can be given through the storage unit 242 to achieve different phase differences between the voltage at the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit and the resonant current IR. Please refer to Figure 8 the schematic diagram of the waveforms of the voltage V1 at the first input terminal of the rectifier circuit and the resonant current IR in the resonant cavity in one switching cycle in another embodiment of the present application shown, and please combine with Figure 5 and Figure 6When the commutation of the resonant current IR changes from negative to positive, when the voltage drop across the third switching transistor Q3 is sampled to increase to (reach) the second voltage threshold Vref2 provided by the storage unit 242, that is, at time t5, the third switching transistor Q3 and the second switching transistor Q2 are controlled to turn off. The corresponding control causes the first switching transistor Q1 and the fourth switching transistor Q4 to conduct. Then, the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 switches to positive only at time t5, and the resonant current IR has switched at time t1. In this way, a second phase difference θ2 is achieved between the voltage V1 at the first input terminal AC1 of the rectifier circuit and the resonant current IR to achieve ASK modulation.

[0065] In one embodiment, the controller 240 is a digital controller, such as a DSP. In digital control, the storage unit 242 can provide voltage thresholds at different levels according to its number of bits. For example, for a six-bit storage unit, it can provide 2 6 -1 (that is, 63) voltage thresholds. It can be seen that the ASK modulation provided by this application has the advantages of multiple levels and multiple gradients, unlike the capacitance modulation method in the prior art, which can only switch between 2 groups, at most 3 groups of communication capacitors and modulation switches. Further, in one embodiment, during the amplitude shift keying modulation, the controller 240 is configured to change the turn-off threshold through the storage unit 242 to change the switching time of the switching transistors in the rectifier circuit. So that during the amplitude shift keying modulation, even for a short period of time, such as including more steps in the data packet of the same bit to optimize packet transmission, which is beneficial to the transmitter to unpack the packet and improves the quality of the ASK modulation packet transmission signal. Please refer to Figure 9 As shown, the amplitude of the unpacked signal is consistent and good, approximately a square wave or a sine wave, so the signal-to-noise ratio (SNR) of the eye diagram is also good.

[0066] In practical applications, the number of bits stored in the storage unit 242 can be determined according to the required level and the quality of the transmitted wave.

[0067] In practical applications, in another embodiment, the turn-off of the switching transistor can be controlled by sampling the current flowing through the switching transistor. For details, please refer to Figure 10Schematic diagram of the internal block diagram of the controller according to another embodiment of the present application. The controller 240 includes a comparator 241, a storage unit 242, and a control signal generation unit 244. The positive input terminal of the comparator 241 is connected to one end of the third switching transistor Q3 to sample the current flowing through the third switching transistor Q3. The negative input terminal of the comparator 241 is connected to the storage unit 242 to receive the current reference signal Iref output by the storage unit 242. The output terminal of the comparator 241 is connected to the control signal generation unit 244. The control signal generation unit 244 outputs a control signal for controlling the third switching transistor Q3 according to the output result of the comparator 241. In this way, the control signal generation unit 244 generates a control signal for controlling the third switching transistor Q3 according to the comparison result between the current sampling signal flowing through the third switching transistor Q3 and the current reference signal Iref.

[0068] Specifically, reference can also be made to Figure 7 , at time t1, when the resonant current IR changes from negative to positive for commutation, the third switching transistor Q3 and the second switching transistor Q2 are still kept conducting until time t2. The current flowing through the third switching transistor Q3 increases to (reaches) the first current threshold Iref1 before controlling the third switching transistor Q3 and the second switching transistor Q2 to turn off. Correspondingly, the control makes the first switching transistor Q1 and the fourth switching transistor Q4 conduct. That is, the turn-off time of the third switching transistor Q3 and the second switching transistor Q2 is controlled to delay the turn-off time of the third switching transistor Q3 and the second switching transistor Q2. In this way, a first phase difference θ1 is achieved between the voltage V1 of the first input terminal AC1 of the rectifier circuit and the resonant current IR.

[0069] Continuing, when the resonant current IR changes from positive to negative for commutation, the first switching transistor Q1 and the fourth switching transistor Q4 still remain conducting, and the third switching transistor Q3 and the second switching transistor Q2 still remain off until the current amplitude flowing through the third switching transistor Q3 increases to (reaches) the first current threshold Iref1 before controlling the first switching transistor Q1 and the fourth switching transistor Q4 to turn off and the third switching transistor Q3 and the second switching transistor Q2 to conduct. That is, the turn-off time of the first switching transistor Q1 and the fourth switching transistor Q4 is controlled to delay the turn-off time of the first switching transistor Q1 and the fourth switching transistor Q4. In this way, a first phase difference θ1 is achieved between the voltage V1 of the first input terminal AC1 of the rectifier circuit and the resonant current IR.

[0070] Reference can also be made to Figure 8 , and the current threshold Iref output by the storage unit 242 can also be changed to the second current threshold Iref2, so that it has a different phase difference from Figure 7 the phase difference between the voltage V1 of the first input terminal AC1 of the rectifier circuit described above and the resonant current IR.

[0071] Such as Figure 10Taking the third switching transistor Q3 as an MOSFET as an example, the positive input terminal of the comparator 241 is connected to the source of the third switching transistor Q3. In practical applications, the specific type of the switching transistor is not limited.

[0072] As described above, when performing amplitude shift keying modulation, the controller 240 is configured to control the turn-off moment of the switching transistor in the rectifier circuit, so that the switching of the internal switching transistor is not synchronized with the resonance current IR change, so that the voltage V1 phase of the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit lags behind the resonance current IR phase, thereby realizing ASK modulation.

[0073] The above voltage threshold Vref and current threshold Iref can be referred to as turn-off thresholds, that is, the controller 240 is configured to change the turn-off threshold through the storage unit 242 therein to change the turn-off moment of the switching transistor in the rectifier circuit.

[0074] As above, taking the rectifier circuit as a full-bridge rectifier circuit and taking the lower transistors (the third switching transistor Q3 and the fourth switching transistor Q4) therein adopting the above control method as an example to illustrate the principle of the present application. For this embodiment, in actual implementation, the second switching transistor Q2 and the third switching transistor Q3 are paired transistors, so the second switching transistor Q2 and the third switching transistor Q3 adopt synchronous control signals. The first switching transistor Q1 is the upper transistor of the same bridge arm as the third switching transistor Q3, so the first switching transistor Q1 and the third switching transistor Q3 adopt complementary control signals. The first switching transistor Q1 and the fourth switching transistor Q4 are paired transistors, so the first switching transistor Q1 and the fourth switching transistor Q4 adopt synchronous control signals.

[0075] It can be seen that the controller 240 of the present application is configured to: obtain the current flowing through a switching transistor in the rectifier circuit or the voltage across the switching transistor; when the current or voltage reaches the turn-off threshold, control the switching transistor to turn off. Further, the turn-off threshold is greater than zero. Further, the turn-off threshold is stored in the storage unit 242 in the controller 240.

[0076] As above, by controlling the switching transistor in the rectifier circuit, the voltage V1 phase of the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit lags behind the resonance current IR phase, thereby realizing ASK modulation. In practical applications, the switching transistor in the rectifier circuit can also be controlled so that the voltage V1 phase of the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit leads the resonance current IR phase, which also changes the gain of the receiver-side resonator 230 and realizes ASK modulation.

[0077] Please refer to Figure 11 the schematic diagram of the waveforms of the voltage V1 at the first input terminal of the rectifier circuit and the resonance current IR in the resonator within one switching period in an embodiment of the present application shown, and please combine Figure 5 、 Figure 6 andFigure 10 When the resonant current IR switches from negative to positive, before time t4, the third switch Q3 and the second switch Q2 are turned on. Then, the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 is zero, and the resonant current IR is negative (with the current direction in Figure 5 being positive) and varies in a sine-wave-like manner. At time t6, when it is sampled that the voltage drop across the third switch Q3 decreases to (i.e., reaches) the third voltage threshold Vref3 provided by the storage unit 242 or the current flowing through the third switch Q3 decreases to (i.e., reaches) the third current threshold Iref3 provided by the storage unit 242, the control is then made such that the third switch Q3 and the second switch Q2 are turned off. Correspondingly, the control makes the first switch Q1 and the fourth switch Q4 turned on. That is, the turn-off time of the third switch Q3 and the second switch Q2 is controlled to turn off the third switch Q3 and the second switch Q2 in advance. Then, the voltage at the first input terminal AC1 of the rectifier circuit 210 is switched to positive in advance. At this time, the resonant current IR is still negative and continues to decrease as it flows through the turned-on first switch Q1 and fourth switch Q4 until time t1 when the resonant current IR sinusoidally changes to zero. Only then does the resonant current IR commutate, causing the voltage V1 at the first input terminal AC1 of the rectifier circuit to lead the resonant current IR in phase.

[0078] For the resonant current IR switching from positive to negative, when it is sampled that the voltage drop across the fourth switch Q4 decreases to (i.e., reaches) the third voltage threshold Vref3 provided by the storage unit 242 or the current flowing through the fourth switch Q4 decreases to (i.e., reaches) the third current threshold Iref3 provided by the storage unit 242, the control is then made such that the first switch Q1 and the fourth switch Q4 are turned off. Correspondingly, the control makes the third switch Q3 and the second switch Q2 turned on. That is, the turn-off time of the first switch Q1 and the fourth switch Q4 is controlled to turn off the first switch Q1 and the fourth switch Q4 in advance. Then, the voltage V1 at the first input terminal AC1 of the rectifier circuit 210 is switched to zero in advance. At this time, the resonant current IR is still positive and continues to decrease as it flows through the turned-on third switch Q3 and second switch Q2 until the resonant current IR sinusoidally changes to zero. Only then does the resonant current IR commutate, causing the voltage V1 at the first input terminal AC1 of the rectifier circuit to lead the resonant current IR in phase.

[0079] In practical applications, the turn-off threshold can be positive or negative, which is related to the position of the sampling circuit that samples the electrical signal representing the switch tube. This will not be elaborated here.

[0080] In an embodiment of the present application, a method for amplitude shift keying modulation of a wireless power transmission system is further provided. In the wireless power transmission system, the receiver includes a cascaded resonator and a rectifier circuit, and a controller. The rectifier circuit includes at least one switching tube, and the controller is configured to control the conduction and turn-off of the switching tube in the rectifier circuit in a synchronous rectification control manner. Please refer to Figure 12 the schematic flow chart of the amplitude shift keying modulation method of the wireless power transmission system according to an embodiment of the present application shown in Figures 5 to 11 , and in combination with

[0081] Furthermore, the turn-off threshold is set such that there is a phase difference between the voltage at one end of the rectifier circuit connected to the resonator (i.e., the first input terminal AC1 or the second input terminal AC2 of the rectifier circuit) and the resonant current in the resonator.

[0082] Furthermore, the turn-off threshold is stored in the storage unit in the controller.

[0083] Furthermore, during the amplitude shift keying modulation, the turn-off threshold is changed to change the turn-off moment of the switching tube in the rectifier circuit.

[0084] Its principle and advantages are the same as those of the above receiver and will not be elaborated here.

[0085] Although the embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure defined by the appended claims.

[0086] In addition, the scope of the present application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, devices, methods, and steps described in the specification. As will be readily understood by those of ordinary skill in the art from the disclosure of the present disclosure, processes, machines, manufactures, compositions of matter, means, methods, or steps that perform substantially the same functions, currently existing or to be developed or implemented later, can achieve substantially the same results as the corresponding embodiments described herein that can be utilized according to the present disclosure. Therefore, the appended claims are intended to include these processes, machines, manufactures, compositions of matter, devices, methods, or steps within their scope.

Claims

1. A receiver, applied to a wireless power transmission system, characterized in that: include: A resonant cavity, comprising a receiver coil and a resonant capacitor connected in series, wherein the receiver coil is used to form wireless power transmission with a transmitter coil of a transmitter in a wireless power transmission system; A rectifier circuit, comprising at least one switch tube, wherein a first input terminal and a second input terminal of the rectifier circuit are respectively connected to two ends of the resonant cavity, and an output terminal of the rectifier circuit is used to connect a load, wherein the receiver adopts an amplitude shift keying modulation mode when transmitting a signal to the transmitter; A controller is used to control the on and off of the switch tube in the rectifier circuit in a synchronous rectification control manner, wherein when performing amplitude shift keying modulation, the switch tube in the rectifier circuit is controlled so that there is a phase difference between the voltage at the first input terminal or the second input terminal of the rectifier circuit and the resonant current in the resonant cavity.

2. The receiver according to claim 1, characterized in that When performing amplitude shift keying modulation, the controller is configured to control the turn-off moment of a switch tube in the rectifier circuit so that there is a phase difference between the voltage at the first input terminal or the second input terminal of the rectifier circuit and the resonant current.

3. The receiver according to claim 2, characterized in that When performing amplitude shift keying modulation, the controller is configured to control the turn-off moment of a switch tube in the rectifier circuit so that the voltage phase at the first input terminal of the rectifier circuit lags behind or leads the resonant current phase, or the voltage phase at the second input terminal lags behind or leads the resonant current phase.

4. The receiver according to claim 2, characterized in that The controller is configured to: Obtaining a current flowing through a switch tube in the rectifier circuit or a voltage across the switch tube; When the current or the voltage reaches a turn-off threshold, the switch tube is controlled to be turned off.

5. The receiver according to claim 4, characterized in that The shutdown threshold is greater than zero.

6. The receiver according to claim 4, characterized in that The shutdown threshold is stored in a storage unit in the controller.

7. The receiver according to claim 6, characterized in that During the amplitude shift keying modulation period, the controller is configured to change the turn-off threshold through the storage unit to change the turn-off moment of the switch tube in the rectifier circuit.

8. An amplitude shift keying modulation method for a wireless power transmission system, wherein the receiver in the wireless power transmission system comprises a resonant cavity and a rectifier circuit connected in cascade, and a controller, the rectifier circuit comprises at least one switch tube, and the controller is used to control the on and off of the switch tube in the rectifier circuit in a synchronous rectification control mode, characterized in that: include: The controller obtains a current flowing through a switch tube in the rectifier circuit or a voltage across the switch tube; When the current or the voltage reaches a turn-off threshold, the switch tube is controlled to be turned off, wherein the turn-off threshold is greater than zero.

9. The amplitude shift keying modulation method of the wireless power transmission system according to claim 8, characterized in that: Also includes: The turn-off threshold is set so that there is a phase difference between the voltage at one end of the rectifier circuit connected to the resonant cavity and the resonant current in the resonant cavity.

10. The amplitude shift keying modulation method of the wireless power transmission system according to claim 9, characterized in that: The shutdown threshold is stored in a storage unit in the controller.

11. The amplitude shift keying modulation method of the wireless power transmission system according to claim 9, characterized in that: During the amplitude shift keying modulation period, the turn-off threshold is changed to change the turn-off moment of the switch tube in the rectifier circuit.

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