POWER RECEIVING APPARATUS, POWER SENDING APPARATUS, AND POWER TRANSMISSION METHOD

Abstract

Embodiments of this application provide a power receiving apparatus, a power sending apparatus, and a power transmission method. A battery and protection circuit module is configured to obtain battery impedance. A first microcontroller module is configured to send a driving signal to an impedance transformation module based on a preset optimal value of input impedance of the impedance transformation module and the battery impedance, to adjust a duty cycle of a driving signal in the impedance transformation module, to enable the impedance transformation module to output a target voltage. The duty cycle is a ratio of high-level duration of the driving signal in one cycle to one cycle. When the impedance transformation module outputs the target voltage, the input impedance is at an optimal value of the input impedance.

Description

This application claims priority to Chinese Patent Application No. 202211081847.8, filed with the China National Intellectual Property Administration on Sep. 6, 2022 and entitled “POWER RECEIVING APPARATUS, POWER SENDING APPARATUS, AND POWER TRANSMISSION METHOD”, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments of this application relate to the field of wireless power transmission technologies, and in particular, to a power receiving apparatus, a power sending apparatus, and a power transmission method.

BACKGROUND

With the development of wireless power transmission technologies, an increasing number of electronic devices are wirelessly charged by using wireless power transmission apparatuses. For example, the electronic devices may be mobile phones, wearable devices, styluses, and the like. A wireless power transmission apparatus generally includes a power sending apparatus and a power receiving apparatus, and a wireless power transmission process is achieved through electromagnetic field coupling between a transmit antenna of the power sending apparatus and a receive antenna of the power receiving apparatus.

Since battery impedance changes in a charging process of a battery, load impedance of the power receiving apparatus changes, and the entire power transmission apparatus cannot transmit with optimal transmission efficiency. In conventional solutions, constant-frequency voltage regulation or constant-voltage frequency regulation is usually used to deal with changes in the load impedance of the power receiving apparatus, but this method sacrifices part of the charging efficiency.

However, due to limitations of the operating frequency band of wireless power transmission, some frequency bands have narrow operating bandwidths, and the load impedance cannot be matched to the optimal impedance by regulating the frequency band. Further, it is impossible to achieve optimal efficiency of the power transmission apparatus in the entire transmission state.

SUMMARY

Embodiments of this application provide a power receiving apparatus, a power sending apparatus, and a power transmission method, to resolve the problem that when some frequency bands have narrow operating bandwidths, a power transmission apparatus cannot achieve optimal efficiency in the entire transmission state because load impedance of the power receiving apparatus has a broad change range, and an optimal value of the load impedance cannot be achieved through frequency regulation, so that the load impedance of the power receiving apparatus can be controlled to the optimal value in real time, to optimize the efficiency of the power transmission apparatus in the entire transmission state.

According to a first aspect, an embodiment of this application shows a power receiving apparatus, including: a battery and protection circuit module, a first microcontroller module, and an impedance transformation module. The battery and protection circuit module is configured to obtain battery impedance. The first microcontroller module is configured to send a driving signal to the impedance transformation module based on a preset optimal value of input impedance of the impedance transformation module and the battery impedance, to adjust a duty cycle of a driving signal in the impedance transformation module, to enable the impedance transformation module to output a target voltage. The duty cycle is a ratio of high-level duration of the driving signal in one cycle to one cycle. When the impedance transformation module outputs the target voltage, the input impedance is at the optimal value of the input impedance.

In the technical solution shown in this embodiment of this application, the power receiving apparatus can control load impedance of the power receiving apparatus to an optimal value in real time through the impedance transformation module, to optimize the efficiency of a power transmission apparatus in the entire transmission state.

In some embodiments, the impedance transformation module is a direct-current impedance converter, and the direct-current impedance converter includes at least one of a single-ended primary inductive converter, a direct-current buck-boost converter, and a direct-current boost-buck converter. In the manner of this embodiment, the power receiving apparatus may select a suitable type of direct-current impedance converter to adjust the load impedance.

In some embodiments, the battery and protection circuit module is further configured to receive the target voltage output by the impedance transformation module, and turn on at least one protection circuit if the target voltage is greater than a rated voltage of the battery. The at least one protection circuit includes at least one transient voltage diode. In the manner of this embodiment, when the target voltage is greater than the maximum voltage of the battery, the battery and protection circuit module protects the battery through the protection circuit to avoid damage to the battery due to overcharging.

In some embodiments, the first microcontroller module is further configured to detect a charge state of the battery and protection circuit module, to determine whether charging of the battery and protection circuit module is completed. The first microcontroller module is further configured to perform voltage detection on the battery and protection circuit module once every delay threshold if the charging of the battery and protection circuit module is not completed, to obtain a detected battery voltage. The battery and protection circuit module is further configured to stop, if the charging of the battery and protection circuit module is completed, receiving the target voltage output by the impedance transformation module. In the manner of this embodiment, the first microcontroller module can detect the charge state of the battery and protection circuit module in real time to determine whether the charging is completed.

In some embodiments, a first communication module is further included. The first microcontroller module is further configured to determine whether the detected battery voltage is equal to the maximum voltage of the battery. The first microcontroller module is further configured to determine detected battery impedance based on the detected battery voltage if the detected battery voltage is equal to the maximum voltage of the battery; and perform next detection to determine whether the charging of the battery and protection circuit module is completed. The first communication module is configured to send the detected battery voltage and the detected battery impedance to a power sending apparatus. In the manner of this embodiment, the first communication module may send the detected battery voltage and the detected battery impedance to the power sending apparatus in real time, to enable the power sending apparatus to adjust target power output by the power sending apparatus based on the values that are sent.

In some embodiments, the first microcontroller module is further configured to determine, if the detected battery voltage is less than the maximum voltage of the battery, whether the detected battery voltage falls within a receive threshold range. The receive threshold represents a deviation degree of the target voltage. The first microcontroller module is further configured to detect the charge state of the battery and protection circuit module a next time if the detected battery voltage falls within the receive threshold range, to determine whether the charging of the battery and protection circuit module is completed. The first microcontroller module is further configured to determine the detected battery impedance based on the detected battery voltage if the detected battery voltage does not fall within the receive threshold range, and detect the charge state of the battery and protection circuit module a next time. In the manner of this embodiment, the first microcontroller module may determine whether the battery voltage falls within a proper deviation range by determining whether the detected battery voltage falls within the receive threshold.

According to a second aspect, this application further shows a power sending apparatus, including: a second communication module, a second microcontroller module, and a power amplifier module. The second communication module is configured to receive a battery voltage and battery impedance sent by a power receiving apparatus. The second microcontroller module is configured to send a control signal to the power amplifier module based on the battery voltage and the battery impedance, to control, through the control signal, the power amplifier module to output target power, where the target power is for enabling input impedance of a direct-current impedance converter in the power receiving apparatus to reach an optimal value of the input impedance. In the manner of this embodiment, the power sending apparatus can send the control signal to the power amplifier module based on the received battery voltage and the received battery impedance to adjust the target power output by the power amplifier module, thereby ensuring that the power transmission apparatus has optimal efficiency in the entire transmission state.

According to a third aspect, an embodiment of this application shows a power transmission apparatus. The power transmission apparatus includes the power receiving apparatus in the first aspect and various implementations of the first aspect and the power sending apparatus in the second aspect and various implementations of the second aspect. An operating frequency band used by the power receiving apparatus and the power sending apparatus to transmit radio frequency energy includes 6.78 MHz and/or 13.56 MHz. In the manner of this embodiment, the power transmission apparatus may ensure optimal efficiency of the transmission state when the operating frequency band is 6.78 MHz and/or 13.56 MHz.

According to a fourth aspect, this application further shows a power transmission method applied to a power receiving apparatus. The method includes: obtaining battery impedance; and sending a driving signal to a direct-current impedance converter based on a preset optimal value of input impedance of the direct-current impedance converter and the battery impedance, to adjust a duty cycle of a driving signal in the direct-current impedance converter, to enable the direct-current impedance converter to output a target voltage. The duty cycle is a ratio of high-level duration of the driving signal in one cycle to one cycle. When the direct-current impedance converter outputs the target voltage, the input impedance is at the optimal value of the input impedance. In the manner of this embodiment, the power receiving apparatus can control load impedance of the power receiving apparatus to an optimal value in real time through the direct-current impedance converter, to optimize the efficiency of a power transmission apparatus in the entire transmission state.

In some embodiments, the method further includes: receiving the target voltage output by the direct-current impedance converter; and turning on at least one protection circuit if the target voltage is greater than a rated voltage of the battery. The at least one protection circuit includes at least one transient voltage diode. In the manner of this embodiment, when the target voltage is greater than the rated voltage of the battery, the power receiving apparatus may protect the battery through the protection circuit to avoid damage to the battery due to overcharging.

In some embodiments, the method further includes: detecting a charge state of the power receiving apparatus, to determine whether charging of the power receiving apparatus is completed; performing voltage detection on the power receiving apparatus once every delay threshold if the charging of the power receiving apparatus is not completed, to obtain a detected battery voltage; and stopping, if the charging of the power receiving apparatus is completed, receiving the target voltage output by the direct-current impedance converter. In the manner of this embodiment, the power receiving apparatus can detect the charge state of the power receiving apparatus in real time to determine whether the charging is completed.

In some embodiments, the method further includes: determining whether the detected battery voltage is equal to the maximum voltage of the battery; determining detected battery impedance based on the detected battery voltage if the detected battery voltage is equal to the maximum voltage of the battery; performing next detection to determine whether the charging of the power receiving apparatus is completed; and sending the detected battery voltage and the detected battery impedance to a power sending apparatus. In the manner of this embodiment, the power receiving apparatus may send the detected battery voltage and the detected battery impedance to the power sending apparatus in real time, to enable the power sending apparatus to adjust target power output by the power sending apparatus based on the values that are sent.

In some embodiments, the method further includes: determining, if the detected battery voltage is less than the maximum voltage of the battery, whether the detected battery voltage falls within a receive threshold range, where the receive threshold represents a deviation degree of the target voltage; detecting the charge state of the power receiving apparatus a next time if the detected battery voltage falls within the receive threshold range, to determine whether the charging of the power receiving apparatus is completed; and determining the detected battery impedance based on the detected battery voltage if the detected battery voltage does not fall within the receive threshold range, and detecting the charge state of the power receiving apparatus a next time. In the manner of this embodiment, the power receiving apparatus may determine whether the battery voltage falls within a proper deviation range by determining whether the detected battery voltage falls within the receive threshold.

According to a fifth aspect, this application further shows a power transmission method, applied to a power sending apparatus. The method includes: receiving a battery voltage and battery impedance sent by a power receiving apparatus; and sending a control signal based on the battery voltage and the battery impedance, to control, through the control signal, the power sending apparatus to output target power. The target power is for enabling input impedance of a direct-current impedance converter in the power receiving apparatus to reach an optimal value of the input impedance. In the manner of this embodiment, the power sending apparatus can send the control signal based on the received battery voltage and the received battery impedance to adjust the target power output by the power sending apparatus, thereby ensuring that load impedance of the power receiving apparatus is controlled at an optimal value in real time.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a simplified schematic diagram of a structure of a power transmission apparatus according to an embodiment of this application;

FIG. 2 is a schematic diagram of a wireless power transmission process according to an embodiment of this application;

FIG. 3 is a schematic diagram of an improved structure of a receiver end impedance transformation module according to an embodiment of this application;

FIG. 4 is a schematic diagram of a structure of a power transmission apparatus 100 according to an embodiment of this application;

FIG. 5 is a schematic diagram of a circuit of a single-ended primary inductive converter according to an embodiment of this application;

FIG. 6 is a schematic diagram of a circuit of a direct-current buck-boost converter according to an embodiment of this application;

FIG. 7 is a schematic diagram of a circuit of a direct-current boost-buck converter according to an embodiment of this application;

FIG. 8 is a partial simplified schematic diagram of a circuit of a power transmission apparatus 100 according to an embodiment of this application; and

FIG. 9 is a flowchart of a power transmission method according to an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following clearly describes technical solutions in embodiments of this application with reference to the accompanying drawings in embodiments of this application.

In the descriptions of this application, “/” means “or” unless otherwise specified. For example, A/B may represent A or B. “And/or” used herein describes only an association relationship for describing associated objects and represents that three relationships may exist. For example, A and/or B may represent the following three cases: Only A exists, both A and B exist, and only B exists. In addition, “at least one” means one or more and “a plurality of” means two or more. The terms, such as “first” and “second”, do not limit a quantity or an execution sequence, and the terms, such as “first” and “second”, do not indicate a definite difference.

It should be noted that in this application, the terms “example” or “for example” is used to represent giving an example, an illustration, or a description. Any embodiment or design solution described by using “example” or “for example” in this application should not be explained as being more preferred or having more advantages than another embodiment or design solution. Exactly, use of the term, such as “example” or “for example”, is intended to present a related concept in a specific manner.

Wireless power transfer (Wireless power transfer, WPT) refers to a power supply-to-load near-field power transfer technology implemented using mechanisms such as magnetic induction, magnetic resonance, and capacitive coupling, to implement wireless power transfer between a power supply and a load, to further charge an electronic device wirelessly.

A type of the electronic device includes, but is not limited to, an electronic device such as a mobile phone, a tablet computer, a notebook computer, a large-screen device (such as a smart TV or a smart screen), a personal computer (personal computer, PC), a handheld computer, a netbook, a personal digital assistant (personal digital assistant, PDA), a wearable electronic device, an in-vehicle device, or a virtual reality device. The electronic device may alternatively be an electronic product such as a wirelessly charged electric vehicle, a wirelessly charged household appliance, and an unmanned aerial vehicle.

FIG. 1 is a simplified schematic diagram of a structure of a power transmission apparatus. As shown in FIG. 1, a power transmission apparatus 100 includes a power sending apparatus (PTU) 101 and a power receiving apparatus (PRU) 102. The power sending apparatus 101 receives input power 103 to generate, through the input power 103, a radiation field 104 for providing energy transfer. The power receiving apparatus 102 is coupled to the radiation field 104 to generate output power 105 for the power receiving apparatus 102 to store or consume.

Further, as shown in FIG. 1, the power sending apparatus 101 may include a power supply module 1011, a transmitter end microcontroller module (Microcontroller Unit, MCU) 1012, a power amplification module 1013, and a transmitter end antenna 1014.

The power supply module 1011 may be configured to receive the input power 103 and input the input power 103 to the power amplification module 1013.

The power amplification module 1013 may be configured to convert direct-current energy of the input power 103 into radio frequency energy.

In this process, the transmitter end microcontroller module 1012 may be configured to adjust an operating frequency of the radio frequency energy converted by the power amplification module 1013, to enable the power amplification module 1013 to generate an operating frequency of a required frequency band. The power amplification module 1013 may be further configured to send the radio frequency energy to the transmitter end antenna 1014 after converting the direct-current energy into the radio frequency energy.

The transmitter end antenna 1014 may be configured to transmit the radio frequency energy to the power receiving apparatus 102.

Correspondingly, the power receiving apparatus 102 includes a receiver end antenna 1021, a receiver end rectifier module 1022, a receiver end impedance transformation module 1023, a receiver end microcontroller module 1024, and a battery module 1025.

When the transmitter end antenna 1014 sends the radio frequency energy to the power receiving apparatus 102, most of the energy in the near field of the transmitter end antenna 1014 can be coupled into the receiver end antenna 1021, so that the transmitter end antenna 1015 and the receiver end antenna 1021 form a near-field coupling mode.

The receiver end antenna 1021 may be configured to send the received radio frequency energy to the receiver end rectifier module 1022 after receiving the radio frequency energy.

The receiver end rectifier module 1022 may be configured to convert the radio frequency energy into direct-current energy, and send the direct-current energy to the receiver end impedance transformation module 1023.

The receiver end impedance transformation module 1023 may be configured to receive a control signal sent by the receiver end microcontroller module 1024, adjust impedance corresponding to the direct-current energy based on the control signal, and generate the output power 105 for the battery module 1025 to store or consume.

It should be noted herein that the structure of the power transmission apparatus 100 shown in FIG. 1 is only for illustrative descriptions. In an actual application, based on this structure, a module may be added to or removed from the power transmission apparatus 100 to implement a required function.

To ensure that the loss of radio frequency energy transmitted between the power sending apparatus 101 and the power receiving apparatus 102 is minimal, it is usually necessary to adjust source impedance of the power sending apparatus 101 and/or adjust load impedance of the power receiving apparatus 102, so that both the source impedance and the load impedance are matched to optimal impedance, to maximize the transmission efficiency of the power transmission apparatus 100 in the entire transmission state.

In a process of performing wireless power transmission between the power sending apparatus 101 and the power receiving apparatus 102, the total efficiency of the power transmission apparatus 100 may be defined as a product of efficiency of all modules in the power sending apparatus 101 and the power receiving apparatus 102, which may be specifically the following formula (1):

$\begin{array}{cc}{\eta }_{\mathrm{total}\mathrm{efficiency}\mathrm{of}\mathrm{power}\mathrm{transmission}}={\eta }_{1013}\times {\eta }_{1014}\times {\eta }_{1021}\times {\eta }_{1022}\times {\eta }_{1023}\times {\eta }_{1025},\mathrm{where}& \left(1\right)\end{array}$

• • η₁₀₁₃ is the efficiency of the power amplification module 1013, η₁₀₁₄ is the efficiency of the transmitter end antenna 1014, η₁₀₂₁ is the efficiency of the receiver end antenna 1021, η₁₀₂₂ is the efficiency of the receiver end rectifier module 1022, η₁₀₂₃ is the efficiency of the receiver end impedance transformation module 1023, and η₁₀₂₅ is the efficiency of the battery module 1025.

To improve the total efficiency of the power transmission apparatus 100 in the entire transmission state, all circuits in the power transmission apparatus 100 are usually designed individually and then combined together, and all the circuits are designed to operate at the highest efficiency. However, it is unavoidable that due to the presence of non-ideal capacitors and non-ideal inductors in the circuits, additional power losses may be introduced to both the power sending apparatus 101 and the power receiving apparatus 102.

FIG. 2 is a schematic diagram of a wireless power transmission process. As shown in FIG. 2, a conventional wireless power transmission process is divided into a pre-charge period, a constant-current period, and a constant-voltage period. During the pre-charge period, the current intensity is kept at C/10, and at this time, the voltage in the battery module 1025 gradually increases to 2.5 V. During the constant-current period, the current intensity is maintained at 1 C, during which the voltage in the battery module 1025 gradually increases from 2.5 V to 4.2 V. During the constant-voltage period, the voltage intensity is maintained at 4.2 V, during which the current intensity gradually decreases from 1 C to C/10 and then remains stable. That is to say, due to a battery characteristic in the battery module 1025, when the output voltage received by the battery module 1025 is a constant voltage, constant current intensity cannot be maintained, and battery impedance changes as a charge state changes, causing the load impedance of the power receiving apparatus 102 to change.

It should be noted herein that, using the battery module 1025 being a lithium battery as an example, inherent resistance of the lithium battery includes resistance of an electrode material, an electrolyte, and a diaphragm, and other internal resistance of a material part. During long-term charge and discharge processes of a lithium battery, a loss of an internal electrolyte of the lithium battery and reduction of activity of various chemical substances gradually increase the battery impedance. During a single charge or discharge process of a lithium battery, battery impedance of the lithium battery is related to a change in temperature and a change in polarization internal resistance. The battery characteristic described in this application refers to a characteristic that a battery impedance changes as a charge state changes during a single charge or discharge process.

The power sending apparatus 101 and the power receiving apparatus 102 may introduce additional power losses. In addition, because when the battery module 1025 receives the output power 105, the characteristic of the battery impedance that changes as the charge state changes may cause the total efficiency to change, the power sending apparatus 101 and the power receiving apparatus 102 may not work with designed performance in actual operation. During circuit design, it is necessary to consider a design manner of maximizing the transmission efficiency of the power transmission apparatus 100 in different usage scenarios.

After a design manner of the circuit in a specific scenario is determined, the inherent efficiency of some modules of the power transmission apparatus 100 is maintained. In the foregoing formula (1), the efficiency η₁₀₂₂ of the receiver end rectifier module 1022 and the efficiency η₁₀₂₃ of the receiver end impedance transformation module 1023 are both inherent efficiency and do not change as the load impedance of the power receiving apparatus 102 changes. Only the efficiency η₁₀₁₃ of the power amplification module 1013, the efficiency η₁₀₁₄ of the transmitter end antenna 1014, and the efficiency η₁₀₂₁ of the receiver end antenna 1021 change as the load impedance changes. Therefore, in the improvement solution of the conventional solution, the module that can change the efficiency is usually improved.

To enable the power transmission apparatus 100 to transmit maximum power, the power transmission apparatus 100 may configure circuits in the entire apparatus based on the principle of optimizing the output power efficiency of the power sending apparatus. The source impedance at one end of the power sending apparatus 101 is kept at a constant value, and frequency regulation is performed through the power amplification module 1013 to match the load impedance of the power receiving apparatus 102 to an optimal impedance.

It should be noted herein that according to the “Interim Provisions on Radio Management of Wireless Charging (Power Transmission) Equipment”, current operating frequency bands of wireless charging can only be used in three frequency bands: 100 to 148.5 kHz, 6765 to 6795 kHz, and 13553 to 13567 kHz. Due to frequency band limitations, the load impedance of the power receiving apparatus 102 cannot be matched to optimal impedance through frequency regulation in some frequency bands. Using the operating frequency bands of 6.78 MHz and 13.56 MHz as an example, bandwidths of the frequency bands are narrow. When the load impedance of the power receiving apparatus 102 changes in a large range, even if the bandwidths of the frequency bands are adjusted to maximum bandwidths, the load impedance of the power receiving apparatus 102 cannot be matched to the optimal impedance in the frequency bands through frequency regulation. Consequently, the transmission efficiency of the entire power transmission apparatus 100 cannot be maximized.

FIG. 3 is a schematic diagram of an improved structure of a receiver end impedance transformation module. As shown in FIG. 3, the receiver end impedance transformation module 1023 includes a radio frequency-direct current converter and a direct current-direct current converter. The radio frequency-direct current converter may be at least one of a switchable fixed capacitor, a switchable fixed inductor, and a voltage-variable capacitor, to be configured to adjust impedance transformation caused by device tolerance. The direct current-direct current converter may be at least one of a buck converter or a boost converter, to be configured to adjust direct-current impedance. In the receiver end impedance transformation module 1023 shown in FIG. 3, when the radio frequency-direct current converter is a switchable fixed capacitor or a switchable fixed inductor, there may be an excessive ohmic loss, resulting in poor practicability. However, at present, most voltage-variable capacitors are ferroelectric apparatuses, micro-electromechanical systems, and varactor diodes, resulting in poor generalizability. Such radio frequency energy transmitted based on tolerance of a regulation device cannot achieve the expected transmission efficiency. When the direct current-direct current converter is a buck converter or a boost converter, a range of impedance transformation is limited, and the load impedance in the power receiving apparatus 102 cannot be matched to the optimal impedance in real time. Consequently, the transmission efficiency of the entire power transmission apparatus 100 cannot be maximized.

Therefore, in the conventional solution, in some frequency bands, the power transmission apparatus 100 cannot control the load impedance of the power receiving apparatus 102 to an optimal value in real time, and further, cannot optimize the efficiency of the power transmission apparatus 100 in the entire transmission state.

To resolve the foregoing technical problems, an embodiment of this application provides a power transmission apparatus 100.

Structures of the power transmission apparatus 100 provided in this embodiment of this application will be described below in detail.

FIG. 4 provides a schematic diagram of a structure of the power transmission apparatus 100 according to an embodiment of this application.

As shown in FIG. 4, the power transmission apparatus 100 in this application includes a power sending apparatus 101 and a power receiving apparatus 102.

It should be noted that the schematic diagram of the structure shown in FIG. 4 is only for illustrative descriptions, and during actual use, replacement, addition, and removal may be performed on parts of the illustrated structure, to implement specific functions.

The power receiving apparatus 102 includes a receive antenna 11, a first matching filter module 12, a rectifier module 13, an impedance transformation module 14, a first microcontroller module 15, a battery and protection circuit module 16, and a first communication module 17.

The power sending apparatus 101 includes a power supply management module 21, a power amplifier module 22, a second matching filter module 23, a transmit antenna 24, a second microcontroller module 25, and a second communication module 26.

It should be noted herein that control logic of both the first microcontroller module 15 and the second microcontroller module 25 that are shown in this embodiment of this application is set based on the principle of optimizing the transmission efficiency of the receive antenna 11 and the transmit antenna 24. The impedance transformation module 14 performs its function based on the principle of optimizing the transmission efficiency of the receive antenna 11 and the transmit antenna 24.

In this embodiment of this application, the total efficiency of the power transmission apparatus 100 is a product of efficiency of all modules in the power sending apparatus 101 and the power receiving apparatus 102, which may be specifically the following formula (2):

$\begin{array}{cc}{\eta }_{\mathrm{total}\mathrm{efficiency}\mathrm{of}\mathrm{power}\mathrm{transmission}}={\eta }_{11}\times {\eta }_{12}\times {\eta }_{13}\times {\eta }_{14}\times {\eta }_{15}\times {\eta }_{16}\times {\eta }_{17}\times {\eta }_{21}\times {\eta }_{22}\times {\eta }_{23}\times {\eta }_{24}\times {\eta }_{25}\times {\eta }_{26},\mathrm{where}& \left(2\right)\end{array}$

• • η₁₁ is the efficiency of the receive antenna 11, η₁₂ is the efficiency of the first matching filter module 12, η₁₃ is the efficiency of the rectifier module 13, η₁₄ is the efficiency of the impedance transformation module 14, η₁₅ is the efficiency of the first microcontroller module 15, η₁₆ is the efficiency of the battery and protection circuit module 16, η₁₇ is the efficiency of the first communication module 17, η₂₁ is the efficiency of the power supply management module 21, η₂₂ is the efficiency of the power amplifier module 22, η₂₃ is the efficiency of the second matching filter module 23, η₂₄ is the efficiency of the transmit antenna 24, η₂₅ is the efficiency of the second microcontroller module 25, and η₂₆ is the efficiency of the second communication module 26.

In this embodiment of this application, because the efficiency of the first matching filter module 12, the efficiency of the rectifier module 13, the efficiency of the impedance transformation module 14, the efficiency of the first microcontroller module 15, the efficiency of the battery and protection circuit module 16, and the efficiency of the first communication module 17, the efficiency of the power supply management module 21, the efficiency of the second matching filter module 23, the efficiency of the second microcontroller module 25, and the efficiency of the second communication module 26 are constant during actual operation of the power transmission apparatus 100, only the efficiency of the power amplifier module 22, the efficiency of the transmit antenna 24, and the efficiency of the receive antenna 11 may change as the load impedance changes in the actual operation of the power transmission apparatus 100.

It should be noted herein that the total antenna efficiency (that is, a product of efficiency of the transmit antenna 24 and efficiency of the receive antenna 11) does not change after the design manner of the circuits is determined, but a change of the load impedance may cause the total antenna efficiency to change. Therefore, when the total antenna efficiency reaches an optimal value, and the load impedance reaches an optimal value, the power amplifier module 22 is designed to match the load impedance, so that the power amplifier module 22 is enabled to adjust output target power, to optimize a value of the source impedance, and further, optimize the efficiency of the power transmission apparatus 100 in the entire transmission state.

In this embodiment of this application, the power supply management module 21 may be configured to receive input power 103 and modulate the input power 103 to send the modulated input power 103 to the power amplifier module 22. The input power 103 may be alternating-current mains power or direct-current power. When the input power 103 is alternating-current mains power, the power supply management module 21 may be configured to modulate the input power 103 into direct-current energy through a full-bridge rectifier circuit, to input the modulated direct-current energy into the power amplifier module 22.

In this embodiment of this application, the power amplifier module 22 may be configured to convert the direct-current energy into radio frequency energy after receiving the direct-current energy sent by the power supply management module 21. The power amplifier module 22 includes, but is not limited to, a class E amplifier, a class D amplifier, a differential class E amplifier, and a differential class D amplifier. The power amplifier module 22 may be further configured to send the radio frequency energy to the second matching filter module 23.

In this embodiment of this application, the second matching filter module 23 includes an electromagnetic compatibility filter (EMC Filter) and an impedance matching network. Among them, the electromagnetic compatibility filter can filter out noise and high frequency harmonics generated by switching on or off a power supply. The second matching filter module 23 may be configured to filter out unnecessary operating frequencies from the radio frequency energy through the electromagnetic compatibility filter after receiving the radio frequency energy sent by the power amplifier module 22, and matches the radio frequency energy to the transmit antenna 24 through the impedance matching network.

In this embodiment of this application, after receiving the radio frequency energy matched through the impedance matching network, the transmit antenna 24 may be configured to send the radio frequency energy to the receive antenna 11. The transmit antenna 24 includes, but is not limited to, at least one of a flexible printed circuit board (Flexible Printed Circuit, FPC) antenna and a wound coil.

It should be noted here that when the transmit antenna 24 is a wound coil, the transmit antenna 24 may include at least one wound coil. A specific quantity of wound coils is not limited in this embodiment of this application. For example, the transmit antenna 24 may include three wound coils, four wound coils, or a larger quantity of wound coils. During actual operation of the transmit antenna 24, one most efficient wound coil may be selected from a plurality of wound coils to transmit the radio frequency energy, and the remaining wound coils do not work. Since the plurality of wound coils may shield interference signals in the power sending apparatus 101, the wound coil configured to send the radio frequency energy can improve the anti-interference and send the radio frequency energy at a required operating frequency.

In this embodiment of this application, the second microcontroller module 25 may control a transmission process of the power sending apparatus 101. The second microcontroller module 25 may be configured to control the power supply management module 21, to enable the power supply management module 21 to modulate the input power 103 into direct-current energy, and may be further configured to control an operating frequency of radio frequency energy converted by the power amplifier module 22, to enable the power amplifier module 22 to generate an operating frequency of a required frequency band.

In this embodiment of this application, the second communication module 26 may be configured to receive information sent by the first communication module 17, to implement communication between the power sending apparatus 101 and the power receiving apparatus 102. The second communication module 26 may implement a wireless connection to the first communication module 17 in an out-of-band communication manner such as Bluetooth (Bluetooth), wireless broadband (Wireless-Fidelity, Wi-Fi), Zigbee protocol (Zigbee), radio frequency identification (Radio Frequency Identification, RFID), a long range (Long range, Lora) wireless technology, near-field communication (Near-Field Communication, NFC).

In this embodiment of this application, when receiving the radio frequency energy sent by the transmit antenna 24, the receive antenna 11 may be configured to send the received radio frequency energy to the first matching filter module 12. The receive antenna 11 includes, but is not limited to, at least one of a flexible printed circuit board antenna and a wound coil.

In this embodiment of this application, the first matching filter module 12 includes an electromagnetic compatibility filter and an impedance matching network. The first matching filter module 12 may be configured to filter out unnecessary operating frequencies from the radio frequency energy through the electromagnetic compatibility filter after receiving the radio frequency energy, adjust an operating frequency of the radio frequency energy through the impedance matching network, and send the radio frequency energy to the rectifier module 13.

In this embodiment of this application, the rectifier module 13 includes, but is not limited to, at least one of a diode rectifier bridge or a metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor, MOS) rectifier bridge. The rectifier module 13 may be configured to convert the radio frequency energy into direct-current energy, and send the direct-current energy to the impedance transformation module 14.

In this embodiment of this application, the impedance transformation module 14 may be configured to receive a driving signal sent by the first microcontroller module 15 to adjust a duty cycle of a driving signal of the impedance transformation module 14 and output a target voltage for storage or consumption by the battery and protection circuit module 16. The impedance transformation module 14 may be a direct-current impedance converter. The direct-current impedance converter includes at least one of a single-ended primary inductive converter (Single-ended Primary Inductive converter, SEPIC), a direct-current buck-boost (Care Unite Skin, CUK) converter, and a direct-current boost-buck (Boost-Buck) converter.

FIG. 5 is a schematic diagram of a circuit of a single-ended primary inductive converter according to an embodiment of this application. As shown in FIG. 5, in the single-ended primary inductive converter, a transformer is replaced with two inductors, so that magnetic elements may be used in a circuit in which the single-ended primary inductive converter is located, which saves the costs of using a dedicated transformer.

FIG. 6 is a schematic diagram of a circuit of a direct-current buck-boost converter according to an embodiment of this application. As shown in FIG. 6, in the direct-current buck-boost converter, there is only one switch, leading to easy control, a duty cycle may be greater than 0.5, and one capacitor transmits energy between the input and the output, which is beneficial to reducing the size and increasing the power density. Moreover, there are inductors at both an input end and an output end, which effectively reduces current pulses at the input end and output end, so that both input and output currents are continuous. A switching current is limited inside the converter, and generates small output ripples and electromagnetic interference.

FIG. 7 is a schematic diagram of a direct-current boost-buck converter according to an embodiment of this application. As shown in FIG. 7, in the direct-current boost-buck converter, input and output currents are continuous, an output voltage has a large adjustable range, and the output voltage may be greater or less than the output voltage, leading to good practicability.

Therefore, for different scenarios, different types of direct-current impedance converters may be arranged on the power receiving apparatus 102 to adjust the target voltage.

In this embodiment of this application, the first microcontroller module 15 may be configured to adjust the duty cycle of the driving signal of the impedance transformation module 14 and detects changes of a battery voltage and battery impedance of the battery and protection circuit module 16.

In this embodiment of this application, the battery and protection circuit module 16 may be configured to receive the target voltage output by the impedance transformation module 14, to store or consume the direct-current energy corresponding to the target voltage.

In this embodiment of this application, the first communication module 17 may be configured to receive the battery voltage and the battery impedance that are detected by the first microcontroller module 15, and transmit the battery voltage and the battery impedance to the second communication module 26, to enable the power receiving apparatus 102 to output target power based on the received battery voltage and the received battery impedance. The first communication module 17 may implement a wireless connection to the second communication module 26 in an out-of-band communication manner such as Bluetooth (Bluetooth), wireless broadband (Wireless-Fidelity, Wi-Fi), Zigbee protocol (Zigbee), radio frequency identification (Radio Frequency Identification, RFID), a long range (Long range, Lora) wireless technology, near-field communication (Near-Field Communication, NFC).

Based on the foregoing manner of arranging the power transmission apparatus, a specific manner in which the first microcontroller module 15 is configured to adjust the duty cycle of the driving signal of the impedance transformation module 14 is as follows:

In this embodiment of this application, an optimal value of input impedance of the impedance transformation module is preset in the first microcontroller module 15. The optimal value of input impedance may be obtained in the following manner:

First, total antenna efficiency is obtained based on a product of efficiency of the receive antenna 11 and efficiency of the transmit antenna 24. Antenna efficiency refers to a ratio of power radiated by an antenna to active power input to the antenna.

FIG. 8 provides a partial simplified schematic diagram of a circuit of the power transmission apparatus 100 according to an embodiment of this application.

In the circuit shown in FIG. 8, efficiency of the receive antenna 11 is:

$\begin{array}{cc}{\eta }_{11}=\frac{R_r}{R_r+R_L},\mathrm{where}& \left(3\right)\end{array}$

• • η₁₁ is the efficiency of the receive antenna 11, R_r is internal resistance of the receive antenna 11, and R_L is equivalent load impedance in the power receiving apparatus.

It should be noted herein that equivalent impedance is a concept in the transmission line theory. In a process of designing a power transmission apparatus, impedance at a specified position on a transmission line, that is, a ratio of voltage to current at this position, needs to be specifically learned of. The equivalent impedance refers to a ratio of an incident wave and a reflected wave after superposition, and exists in a form of a position function. The equivalent impedance changes with as the position changes. The equivalent impedance relates to a perspective problem. For example, impedance from a perspective toward a load is equivalent load impedance, and impedance from a perspective toward a source is equivalent source impedance. In this embodiment of this application, R_L is load impedance.

The efficiency of the transmit antenna 24 is:

$\begin{array}{cc}{\eta }_{24}=\frac{R_{\mathrm{eq}}}{R_{\mathrm{eq}}+R_t},\mathrm{where}& \left(4\right)\end{array}$

• • η₂₄ is efficiency of the transmit antenna 24, R_eq is equivalent load impedance of the power receiving apparatus in the power sending apparatus, R_t is internal resistance of the transmit antenna 24.

In this case, total antenna efficiency η_total is:

$\begin{array}{cc}{\eta }_{\mathrm{total}}={\eta }_{24}\times {\eta }_{11}=\frac{R_{\mathrm{eq}}}{R_{\mathrm{eq}}+R_t}\times \frac{R_r}{R_r+R_L}.& \left(5\right)\end{array}$ $\begin{array}{cc}\mathrm{Let}{Q}_t=\frac{\omega L_t}{R_t}& \left(6\right)\end{array}$ $\begin{array}{cc}\mathrm{and}{Q}_r=\frac{\omega L_r}{R_r},\mathrm{where}& \left(7\right)\end{array}$

• • Q_t is a quality factor of the transmit antenna 24, Q_r is a quality factor of the receive antenna 11, ω is an angular frequency, L_t is inductance of the transmit antenna 24, and L_r is inductance of the receive antenna 11.

In this case,

$\begin{array}{cc}{\eta }_{\mathrm{total}}=\frac{\frac{{\omega }^2{M}^2}{R_r+R_L}}{\frac{{\omega }^2{M}^2}{R_r+R_L}+R_t}\times \frac{R_r}{R_r+R_L}=\frac{k^2{Q}_t{Q}_r{R}_L}{\frac{{R_L}^2}{R_r}+R_L\left(2+k^2{Q}_t{Q}_r\right)+R_r\left(1+k^2{Q}_t{Q}_r\right)},\mathrm{where}& \left(8\right)\end{array}$

• • k is a coupling coefficient between coils.

By deriving a formula (8), an extremum can be obtained.

Letting η′_total=0, it can be obtained that a maximum of the total antenna efficiency is:

$\begin{array}{cc}{\eta }_{\mathrm{total}}=\frac{k^2{Q}_t{Q}_r}{(1+\sqrt{1+{\left(k^2{Q}_t{Q}_r\right)}^2}}.& \left(9\right)\end{array}$

In this case, let:

$\begin{array}{cc}{R}_L=R_r\sqrt{1+{\left(k^2{Q}_t{Q}_r\right)}^2}.& \left(10\right)\end{array}$

Subsequently, using the rectifier module 13 being a diode rectifier bridge as an example, an impedance transformation rule corresponding to the rectifier module 13 is:

$\begin{array}{cc}{Z}_L=\frac{8}{{\pi }^2}{R}_L,\mathrm{where}& \left(11\right)\end{array}$

• • Z_L is load impedance from a perspective the rectifier module, and in addition, is equal to input impedance of the impedance transformation module 14.

To ensure that the input impedance Z_L of the impedance transformation module 14 is fixed at an optimal value,

$\begin{array}{cc}{Z}_L=\left(1-D^2\right)\frac{R}{D^2}=\frac{8}{{\pi }^2}{R}_r\sqrt{1+{\left(k^2{Q}_t{Q}_r\right)}^2},\mathrm{where}& \left(12\right)\end{array}$

• • R is the battery impedance, and D is the duty cycle of the driving signal in the impedance transformation module 14.

An optimal value of the input impedance of the impedance transformation module 14 may be obtained based on the calculation method of the formula (12).

The first microcontroller module 15 presets the optimal value of the input impedance of the impedance transformation module 14.

The first microcontroller module 15 may be further configured to send the driving signal to the impedance transformation module 14 based on the preset optimal value of the input impedance and the battery impedance to adjust the duty cycle of the driving signal in the impedance transformation module 14. A value of the duty cycle is calculated based on the following formula (13):

$\begin{array}{cc}D=\sqrt{\frac{R}{R+\frac{{\pi }^2}{8}{R}_r\sqrt{\sqrt{1+{\left(k^2{Q}_t{Q}_r\right)}^2}}}}.& \left(13\right)\end{array}$

It should be noted herein that a duty cycle is a ratio of high-level duration of a driving signal in one cycle to one cycle. For example, if one driving cycle of a driving signal is 2 microseconds, where high-level duration is 1 microsecond, a duty cycle is 50%.

In a specific implementation, the first microcontroller module 15 controls a voltage average of a voltage signal by adjusting the duty cycle of the driving signal in the impedance transformation module 14, to enable the impedance transformation module 14 to output the target voltage. When the impedance transformation module 14 outputs the target voltage, the input impedance of the impedance transformation module 14 is at the optimal value of the input impedance. It should be noted herein that the duty cycle is determined based on the optimal value of the input impedance and the battery impedance. Since the optimal value of the input impedance is a preset value, and the battery impedance is a variable obtained in real time, the duty cycle changes as the battery impedance changes, the target voltage output by the impedance transformation module 14 changes as the duty cycle changes. In this case, load impedance from the perspective of the rectifier module 13 is fixed at an optimal value, and the impedance transformation module 14 fixes the input impedance at the optimal value, so that load impedance of the power receiving apparatus 102 is fixed at an optimal value.

To ensure that the load impedance of the power receiving apparatus is at the optimal value, radio frequency energy received by the power receiving apparatus 102 should have a constant value. According to the energy conservation law, operating power of the battery and protection circuit module 16 remains unchanged, that is:

$P_{\mathrm{power}}=\frac{{V_{\mathrm{out}}}^2}{R},$

where

• • P_power is the operating power of the battery and protection circuit module 16, V_out is the battery voltage, and R is the battery impedance.

P_power is a constant value. When the battery impedance increases, the battery voltage increases. When the battery impedance decreases, the battery voltage decreases. Due to a limited range of an operating voltage of the battery, when the battery voltage increases, it is possible that the battery voltage exceeds a maximum voltage. In addition, the power sending apparatus 101 needs to adjust the target power output by the transmit antenna 24 in real time based on the battery voltage and the battery impedance, to enable the load impedance from the perspective of the rectifier module 13 to at the optimal value.

Based on this, the first microcontroller module 15 is further configured to detect the battery and protection circuit module 16 to avoid overcharging of the battery and protection circuit module 16, and transmit the battery impedance and the battery voltage to the power sending apparatus 101 in real time. A specific manner is as follows:

The first microcontroller module is 15 further configured to detect a charge state of the battery and protection circuit module 16, to determine whether charging of the battery and protection circuit module 16 is completed.

In a specific implementation, the charging is performed with a voltage that is a constant voltage, and the charging is performed with a current that is a trickle. The charging of the battery and protection circuit module 16 is considered to be completed until the electric current is less than a specific set value.

In this embodiment of this application, the first microcontroller module 15 is further configured to perform voltage detection on the battery and protection circuit module once every delay threshold if the charging of the battery and protection circuit module 16 is not completed, to obtain a detected battery voltage. For example, the delay threshold may be set to 3 microseconds, and in this embodiment of this application, the delay threshold is only for illustrative descriptions, and may be specifically set according to actual conditions. The delay threshold is actually duration of communication between the first communication module 17 and the second communication module 26. The setting of the delay threshold may ensure a frequency of communication between the first communication module 17 and the second communication module 26, to enable the transmit antenna 24 to adjust the output target power in real time.

In this embodiment of this application, the battery and protection circuit module 16 is further configured to stop, if the charging of the battery and protection circuit module 16 is completed, receiving the target voltage output by the impedance transformation module 14. For example, a maximum voltage of the battery of the battery and protection circuit module 16 is 5 V. When the target voltage received by the battery and protection circuit module 16 is 5 V and the current is less than C/10, receiving of the target voltage output by the impedance transformation module 14 is stopped.

In this embodiment of this application, the battery and protection circuit module 16 may be further configured to receive the target voltage output by the impedance transformation module 14, and turn on at least one protection circuit if the target voltage is greater than the maximum voltage of the battery, where the at least one protection circuit includes at least one transient voltage diode (Transient Voltage Suppressor, TVS). In this way, when the battery impedance increases, the equivalent load impedance of the power receiving apparatus increases, and the target voltage output by the impedance transformation module 14 increases. Using the maximum voltage being 5 V as an example, when the target voltage is 5.5 V, that is, is greater than 5 V, at least one protection circuit is immediately turned on to avoid overcharge damage to the battery.

In this embodiment of this application, the first microcontroller module 15 may be further configured to determine whether the detected battery voltage is equal to the maximum voltage of the battery, determine detected battery impedance based on the detected battery voltage if the detected battery voltage is equal to the maximum voltage of the battery, and perform next detection to determine whether the charging of the battery and protection circuit module is completed.

For example, the maximum voltage of the battery and protection circuit module 16 is set to 5 V, and the delay threshold is set to 3 microseconds. When detecting that a voltage value of the battery is 4.8 V, the first microcontroller module 15 may detect the battery voltage again after 3 microseconds, and obtain a detected voltage value of 5 V. Therefore, after the detected battery voltage is equal to the maximum voltage of the battery, the first microcontroller module 15 also needs to detect a charge state of the battery and protection circuit module 16 to determine whether the charging is completed, to avoid overcharging.

In this embodiment of this application, the first microcontroller module 15 may be further configured to determine, if the detected battery voltage is less than the maximum voltage of the battery, whether the detected battery voltage falls within a receive threshold range, where a receive threshold represents a deviation degree of the target voltage; detect the charge state of the battery and protection circuit module a next time if the detected battery voltage falls within the receive threshold range, to determine whether the charging of the battery and protection circuit module is completed; and determine the detected battery impedance based on the detected battery voltage if the detected battery voltage does not fall within the receive threshold range, and detect the charge state of the battery and protection circuit module a next time.

It should be noted herein that the target voltage fluctuates in an actual output process, which will cause a voltage deviation when the battery voltage receives the target voltage. Based on this, the first microcontroller module 15 sets a receive threshold to determine whether the battery voltage exceeds a proper deviation degree.

For example, the receive threshold may be set to [0.95×V_nominal, 1.05×V_nominal], where V_nominal is the target voltage. For example, the target voltage is 4.2 V, the battery voltage is 4.1 V, and the receive threshold is [0.95×4.2 V, 1.05×4.2 V]. In this case, the battery voltage falls within the receive threshold range, indicating that the battery voltage falls within a proper deviation range.

If the battery voltage exceeds the receive threshold, battery impedance corresponding to a current battery voltage needs to be recalculated based on the current battery voltage, to enable the power sending apparatus 101 to output the target power based on the current battery voltage and the battery impedance corresponding to the current battery voltage.

In this embodiment of this application, the first communication module 17 may be further configured to send the detected battery voltage and the detected battery impedance to the power sending apparatus 101, to enable the power sending apparatus 101 to adjust the output target power.

Since the first communication module 17 sends the detected battery voltage and the detected battery impedance to the second communication module 26 in real time, when a value of the target voltage output by the impedance transformation module 14 is too high, the power sending apparatus 101 adjusts the output target power based on the received battery voltage and the received battery impedance, to reduce the target voltage. It should be noted that it is possible that the power sending apparatus 101 cannot immediately reduce the target voltage to an expected range based only on the battery voltage and the battery impedance that are sent once, and instead, the power sending apparatus 101 needs to perform adjustment a plurality of times based on the battery voltages and the battery impedance that are sent a plurality of times, to reduce the target voltage to the expected range.

To optimize the efficiency of the power receiving apparatus 102 in the transmission state, it is necessary to ensure that the source impedance is also at an optimal value when the load impedance is an optimal value. The first communication module 17 may be configured to send the battery voltage and the battery impedance to the second communication module 26, to enable the power amplifier module 22 to output the target power based on the battery voltage and the battery impedance.

In this embodiment of this application, the second communication module 26 is configured to receive the battery voltage and the battery impedance that are sent by the first communication module 17.

The second microcontroller module 25 may be configured to send a control signal to the power amplifier module 22 based on the battery voltage and the battery impedance after the second communication module 26 receives the battery voltage and the battery impedance, to adjust the operating frequency of the power amplifier module 22, so that the power amplifier module 22 transmits the target power when the source impedance is at an optimal value.

The target power may be obtained in the following manner:

$P_{\mathrm{output}}=\frac{{V_{\mathrm{nominal}}}^2}{R\times {\eta }_{\mathrm{total}}},$

where

• • P_output is the target power, V_nominal is the target voltage, R is the battery impedance, and η_total is the total antenna efficiency.

It should be noted that, because a communication duration delay exists between the first communication module 17 and the second communication module 26, the target power is usually adjusted based on an expected voltage rather than the target voltage.

In this embodiment of this application, the operating frequency band of the power transmission apparatus includes 6.78 MHz and/or 13.56 MHz. This embodiment of this application may also be applied to other operating frequency bands. The technical solution shown in this embodiment of this application may cover more frequency bands to optimize efficiency of the power transmission apparatus 100 in the entire transmission state.

It can be learned from the foregoing technical solution that the power transmission apparatus shown in this embodiment of this application can resolve the problem that when some frequency bands have narrow operating bandwidths, the power transmission apparatus cannot achieve optimal efficiency in the entire transmission state because load impedance of the power receiving apparatus has a broad change range, and an optimal value of the load impedance cannot be achieved through frequency regulation, so that the load impedance of the power receiving apparatus can be controlled to the optimal value in real time, to optimize the efficiency of the power transmission apparatus in the entire transmission state.

An embodiment of this application further provides a power transmission method.

FIG. 9 is a schematic flowchart of a power transmission method according to an embodiment of this application. As shown in FIG. 9, the power transmission method provided in this embodiment of this application is applied to a power receiving apparatus. The method includes the following steps:

S1: Obtain battery impedance.

S2: Send a driving signal to a direct-current impedance converter based on a preset optimal value of input impedance of the direct-current impedance converter and the battery impedance, to adjust a duty cycle of a driving signal in the direct-current impedance converter, to enable the direct-current impedance converter to output a target voltage, where the duty cycle is a ratio of high-level duration of the driving signal in one cycle to one cycle, and when the direct-current impedance converter outputs the target voltage, the input impedance is at the optimal value of the input impedance.

S3: Send a battery voltage and the battery impedance to a power sending apparatus.

In some embodiments, the method further includes: receiving the target voltage output by the direct-current impedance converter; and turning on at least one protection circuit if the target voltage is greater than a rated voltage of the battery. The at least one protection circuit includes at least one transient voltage diode.

In some embodiments, the method further includes: detecting a charge state of the power receiving apparatus, to determine whether charging of the power receiving apparatus is completed; performing voltage detection on the power receiving apparatus once every delay threshold if the charging of the power receiving apparatus is not completed, to obtain a detected battery voltage; and stopping, if the charging of the power receiving apparatus is completed, receiving the target voltage output by the direct-current impedance converter.

In some embodiments, the method further includes: determining whether the detected battery voltage is equal to the maximum voltage of the battery; determining detected battery impedance based on the detected battery voltage if the detected battery voltage is equal to the maximum voltage of the battery; performing next detection to determine whether the charging of the battery and protection circuit module is completed; and sending the detected battery voltage and the detected battery impedance to the power sending apparatus.

In some embodiments, the method further includes: determining, if the detected battery voltage is less than the maximum voltage of the battery, whether the detected battery voltage falls within a receive threshold range, where a receive threshold represents a deviation degree of the target voltage; detecting the charge state of the power receiving apparatus a next time if the detected battery voltage falls within the receive threshold range, to determine whether the charging of the power receiving apparatus is completed; and determining the detected battery impedance based on the detected battery voltage if the detected battery voltage does not fall within the receive threshold range, and detecting the charge state of the power receiving apparatus a next time.

The power transmission method provided by this embodiment of this application is also applied to the power sending apparatus. The method includes:

S4: Receive the battery voltage and the battery impedance sent by the power receiving apparatus.

S5: Send a control signal based on the battery voltage and the battery impedance, to control, through the control signal, the power sending apparatus to output the target power, where the target power is for enabling the input impedance of the direct-current impedance converter in the power receiving apparatus to reach an optimal value of the input impedance.

In the power transmission method provided in this embodiment of this application, the operating frequency band used to transmit radio frequency energy includes 6.78 MHz and/or 13.56 MHz.

It can be learned from the foregoing technical solution that the power transmission method shown in this embodiment of this application can resolve the problem that when some frequency bands have narrow operating bandwidths, the power transmission apparatus cannot achieve optimal efficiency in the entire transmission state because load impedance of the power receiving apparatus has a broad change range, and an optimal value of the load impedance cannot be achieved through frequency regulation, so that the load impedance of the power receiving apparatus can be controlled to the optimal value in real time, to optimize the efficiency of the power transmission apparatus in the entire transmission state.

An embodiment of this application further provides a wireless charger, including the power sending apparatus provided in an embodiment of this application and any implementation thereof.

An embodiment of this application further provides an electronic device, including the power receiving apparatus provided in an embodiment of this application and any implementation thereof, and/or the power sending apparatus (configured to implement a wireless reverse charge function) provided in an embodiment of this application and any implementation thereof. A type of the electronic device includes, but is not limited to, an electronic device such as a mobile phone, a tablet computer, a notebook computer, a large-screen device (such as a smart TV or a smart screen), a personal computer (personal computer, PC), a handheld computer, a netbook, a personal digital assistant (personal digital assistant, PDA), a wearable electronic device, an in-vehicle device, or a virtual reality device. The electronic device may alternatively be an electronic product such as a wirelessly charged electric vehicle, a wirelessly charged household appliance, a wirelessly charged headphone, and an unmanned aerial vehicle.

It should be understood that in various embodiments of embodiments in this application, an order of sequence numbers of the foregoing processes does not indicate an execution sequence, and execution sequences of the processes should be determined according to functions and internal logic thereof and should not impose any limitation on an implementation process of the embodiments.

The parts of this specification are all described in a progressive manner, for same or similar parts in the embodiments, refer to such embodiments, and descriptions of each embodiment focus on a difference from other embodiments. Especially, apparatus and system embodiments are basically similar to a method embodiment, and therefore are described briefly. For related parts, reference may be made to partial descriptions in the method embodiment.

The foregoing specific implementations further describe the objectives, technical solutions in detail, and beneficial effects of the present invention. It should be appreciated that the foregoing descriptions are merely specific implementations of the present invention, but are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, or improvement made based on the technical solutions of the present invention should fall within the protection scope of the present invention.

Claims

1-14. (canceled)

15. A power receiving apparatus, comprising: a battery and protection circuit apparatus, a first microcontroller apparatus, an impedance transformation apparatus, and a first communication apparatus, wherein the first microcontroller apparatus is configured to perform voltage detection on the battery and protection circuit apparatus to obtain a battery voltage, determine battery impedance based on the battery voltage, and send a driving signal to the impedance transformation apparatus based on a preset constant value and the battery impedance, wherein the constant value represents a value of input impedance of the impedance transformation apparatus;the impedance transformation apparatus is configured to output a target voltage to the battery and protection circuit apparatus based on the driving signal, wherein the target voltage is an output voltage of the impedance transformation apparatus obtained by adjusting an input voltage of the impedance transformation apparatus based on the driving signal;the battery and protection circuit apparatus is further configured to receive the target voltage output by the impedance transformation apparatus; andthe first communication apparatus is configured to send the target voltage and the battery impedance to a power sending apparatus, the target voltage and the battery impedance are used to enable the power sending apparatus to calculate target power based on the target voltage and the battery impedance, and adjust the target voltage based on the target power.

16. The power receiving apparatus according to claim 15, wherein the first microcontroller apparatus is specifically configured to adjust a duty cycle of the driving signal based on a preset constant value and the battery impedance, wherein the duty cycle is a ratio of high-level duration of the driving signal in one cycle to one cycle; andwhen the impedance transformation apparatus outputs the target voltage, the input impedance of the impedance transformation apparatus is at the preset constant value.

17. The power receiving apparatus according to claim 15, wherein the target power is a ratio of a square of the target voltage to a product of the battery impedance and total antenna efficiency.

18. The power receiving apparatus according to claim 17, wherein the first communication apparatus is specifically configured to send the target voltage and the battery impedance to the power sending apparatus, to enable the power sending apparatus to calculate the target power based on the target voltage, the battery impedance, and the total antenna efficiency, and adjust the target voltage based on the target power.

19. The power receiving apparatus according to the claim 15, wherein the impedance transformation apparatus is a direct-current impedance converter, and the direct-current impedance converter comprises at least one of a single-ended primary inductive converter, a direct-current buck-boost converter, and a direct-current boost-buck converter.

20. The power receiving apparatus according to claim 15, wherein the battery and protection circuit apparatus is further configured to receive the target voltage output by the impedance transformation apparatus; and turn on at least one protection circuit if the target voltage is greater than a maximum voltage of the battery, wherein the at least one protection circuit comprises at least one transient voltage diode.

21. The power receiving apparatus according to claim 15, wherein the first microcontroller apparatus is specifically configured to detect a charge state of the battery and protection circuit apparatus, to determine whether charging of the battery and protection circuit apparatus is completed; and perform voltage detection on the battery and protection circuit apparatus once every delay threshold if the charging of the battery and protection circuit apparatus is not completed, to obtain the battery voltage; andthe battery and protection circuit apparatus is further configured to stop, if the charging of the battery and protection circuit apparatus is completed, receiving the target voltage output by the impedance transformation apparatus.

22. The power receiving apparatus according to claim 21, wherein the first microcontroller apparatus is further configured to determine whether the battery voltage is equal to the maximum voltage of the battery;the first microcontroller apparatus is further configured to determine the battery impedance based on the detected battery voltage if the battery voltage is equal to the maximum voltage of the battery, and detect the charge state of the battery and protection circuit apparatus again.

23. The power receiving apparatus according to claim 22, wherein the first microcontroller apparatus is further to determine, if the detected battery voltage is less than the maximum voltage of the battery, whether the detected battery voltage falls within a receive threshold range, wherein a receive threshold represents a deviation degree of the target voltage;the first microcontroller apparatus is further configured to detect the charge state of the battery and protection circuit apparatus again if the detected battery voltage falls within the receive threshold range, to determine whether the charging of the battery and protection circuit apparatus is completed; andthe first microcontroller apparatus is further configured to determine the battery impedance based on the detected battery voltage if the detected battery voltage does not fall within the receive threshold range, and detect the charge state of the battery and protection circuit apparatus again.

24. A power sending apparatus, comprising: a second communication apparatus, a second microcontroller apparatus, and a power amplifier apparatus, wherein the second communication apparatus is configured to receive a target voltage and battery impedance that are sent by the power receiving apparatus; wherein the receiving apparatus comprising a battery and protection circuit apparatus, a first microcontroller apparatus, an impedance transformation apparatus, and a first communication apparatus, whereinthe first microcontroller apparatus is configured to perform voltage detection on the battery and protection circuit apparatus to obtain a battery voltage, determine battery impedance based on the battery voltage, and send a driving signal to the impedance transformation apparatus based on a preset constant value and the battery impedance, wherein the constant value represents a value of input impedance of the impedance transformation apparatus;the impedance transformation apparatus is configured to output a target voltage to the battery and protection circuit apparatus based on the driving signal, wherein the target voltage is an output voltage of the impedance transformation apparatus obtained by adjusting an input voltage of the impedance transformation apparatus based on the driving signal;the battery and protection circuit apparatus is further configured to receive the target voltage output by the impedance transformation apparatus; andthe first communication apparatus is configured to send the target voltage and the battery impedance to a power sending apparatus, the target voltage and the battery impedance are used to enable the power sending apparatus to calculate target power based on the target voltage and the battery impedance, and adjust the target voltage based on the target power;the second microcontroller apparatus is configured to send a control signal to the power amplifier apparatus based on the target voltage and the battery impedance, to control, through the control signal, the power amplifier apparatus to output target power, wherein the target power is for adjusting the target voltage, the target voltage is an output voltage of a direct-current impedance converter in the power receiving apparatus, and input impedance of the direct-current impedance converter is a preset constant value.

25. The power sending apparatus according to claim 24, wherein the target power is a ratio of a square of the target voltage to a product of the battery impedance and total antenna efficiency.

26. (canceled)

27. A power transmission method applied to a power receiving apparatus, wherein the method comprises: performing voltage detection on the battery and protection circuit apparatus to obtain a battery voltage, determine battery impedance based on the battery voltage, and send a driving signal to an impedance transformation apparatus based on a preset constant value and the battery impedance, wherein the constant value represents a value of input impedance of the impedance transformation apparatus;outputting a target voltage to the battery and protection circuit apparatus based on the driving signal, wherein the target voltage is an output voltage of the impedance transformation apparatus obtained by adjusting an input voltage of the impedance transformation apparatus based on the driving signal;obtaining the target voltage output by the impedance transformation apparatus; andsending the target voltage and the battery impedance to a power sending apparatus, the target voltage and the battery impedance are used to enable the power sending apparatus to calculate target power based on the target voltage and the battery impedance, and adjust the target voltage based on the target power.

28. The power transmission method according to claim 27, wherein the outputting a target voltage to the battery and protection circuit apparatus based on the driving signal comprises: adjust a duty cycle of the driving signal based on a preset constant value and the battery impedance, wherein the duty cycle is a ratio of high-level duration of the driving signal in one cycle to one cycle; andwhen the impedance transformation apparatus outputs the target voltage, the input impedance of the impedance transformation apparatus is at the preset constant value.

29. The power transmission method according to claim 27, wherein the target power is a ratio of a square of the target voltage to a product of the battery impedance and total antenna efficiency.

30. The power transmission method according to claim 29, wherein the sending the target voltage and the battery impedance to a power sending apparatus, to enable the power sending apparatus to calculate target power based on the target voltage and the battery impedance, and adjust the target voltage based on the target power, comprises: sending the target voltage and the battery impedance to the power sending apparatus, to enable the power sending apparatus to calculate the target power based on the target voltage, the battery impedance, and the total antenna efficiency, and adjust the target voltage based on the target power.

31. The power transmission method according to claim 27, wherein the method further comprises: receiving the target voltage output by the direct-current impedance converter; and turning on at least one protection circuit if the target voltage is greater than a rated voltage of the battery, wherein the at least one protection circuit comprises at least one transient voltage diode.

32. The power transmission method according to claim 31, wherein the performing voltage detection on the battery and protection circuit apparatus to obtain a detected battery voltage comprises: detecting a charge state of the power receiving apparatus, to determine whether charging of the power receiving apparatus is completed;performing voltage detection on the power receiving apparatus once every delay threshold if the charging of the power receiving apparatus is not completed, to obtain the detected battery voltage; andstopping, if the charging of the power receiving apparatus is completed, receiving the target voltage output by the direct-current impedance converter.

33. The power transmission method according to claim 32, wherein the method further comprises: determining whether the detected battery voltage is equal to the maximum voltage of the battery; anddetermining the battery impedance based on the detected battery voltage if the detected battery voltage is equal to the maximum voltage of the battery, and performing detection again to determine whether the charging of the power receiving apparatus is completed.

34. The power transmission method according to claim 32, wherein the method further comprises: determining, if the detected battery voltage is less than the maximum voltage of the battery, whether the detected battery voltage falls within a receive threshold range, wherein the receive threshold represents a deviation degree of the target voltage;detecting the charge state of the power receiving apparatus again if the detected battery voltage falls within the receive threshold range, to determine whether the charging of the power receiving apparatus is completed; anddetermining the battery impedance based on the detected battery voltage if the detected battery voltage does not fall within the receive threshold range, and detecting the charge state of the power receiving apparatus again.

35. (canceled)