# US 2019/0379230 A1 · Increasing efficiency in wireless chargers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0379230 A1 - Document ID: US20190379230A1 - Status: Published application - Kind: A1 - Application number: 16/004,768 - Filed: 2018-06-11 - Published: 2019-12-12 - Earliest claimed: 2018-06-11 - Applicants: Google LLC - Inventors: Xuelin Wu; Honggang Sheng - Web page: https://patentgrep.com/patent/US20190379230A1 ## CPC - H02J 7/933: {the cycle being controlled or terminated in response to electric parameters} - H02J 7/06: using discharge tubes or semiconductor devices - H02J 50/12: of the resonant type - H02J 50/80: involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices - H02J 7/42: with electronic devices having internal batteries, e.g. mobile phones - H02J 2207/20: Charging or discharging characterised by the power electronics converter - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY ## Abstract Methods, systems, and apparatus for high-efficiency wireless charging are presented. The system can include a transmitter for generating a transmitted power signal and a receiver for converting the transmitted power signal to a DC signal for charging a battery. The receiver can include (i) an inductive coil, which generates an AC signal in the presence of the transmitted power signal, (ii) a conversion circuit, which converts the AC signal generated by the coil to a DC output signal, (iii) a charging circuit comprising one or more switched capacitors, which converts the DC output signal to a DC charging signal, and (iv) a controller, which measures a signal of the battery indicating a charge level of the battery. Based on determining that the relationship between the DC charging signal and the signal of the battery satisfies the predetermined criterion, the controller generates a control signal to adjust the AC signal. ## Claims ### Claim 1 A receiver for a wireless charging system comprising: an inductive coil configured to generate an AC signal in the presence of a magnetic field; a conversion circuit configured to convert the AC signal generated by the inductive coil to a DC output signal, wherein a voltage level of the DC output signal is a function of one or more characteristics of the AC signal generated by the inductive coil; a charging circuit configured to: convert the DC output signal to a DC charging signal, wherein the voltage level of the DC charging signal has a fixed relationship to the voltage level of the DC output signal and the voltage level of the DC charging signal is less than the voltage level of the DC output signal; and provide the DC charging signal to a battery; and a controller configured to: measure a signal of the battery that corresponds to a charge level of the battery; based on the signal of the battery, determine that a relationship between the DC charging signal and the signal of the battery satisfies a predetermined criterion; and based on determining that the relationship between the DC charging signal and the signal of the battery satisfies the predetermined criterion, generate a control signal to adjust the AC signal. ### Claim 2 (depends on 1) The receiver of claim 1, wherein the conversion circuit comprises: an impedance matching circuit; a rectifying circuit; and a voltage regulating circuit. ### Claim 3 (depends on 2) The receiver of claim 2, wherein the rectifying circuit comprises one or more of a full-wave diode bridge rectifier or an active switching rectifier. ### Claim 4 (depends on 2) The receiver of claim 2, wherein the voltage regulating circuit comprises one or more of a linear voltage regulator or a switching voltage regulator. ### Claim 5 (depends on 1) The receiver of claim 1, wherein the voltage level of the DC output signal is determined based on one or more characteristics of the AC signal generated by the inductive coil comprises the voltage level of the DC output signal is determined based on one or more of a voltage level of the AC signal or a frequency of the AC signal. ### Claim 6 (depends on 1) The receiver of claim 1, wherein the charging circuit comprises one or more switched capacitor circuits. ### Claim 7 (depends on 1) The receiver of claim 1, wherein the voltage level of the generated DC charging signal is one half or one quarter of the voltage level of the DC output signal. ### Claim 8 (depends on 1) The receiver of claim 1, wherein the signal of the battery that indicates a charge level of the battery comprises a current signal of the battery or a voltage signal of the battery. ### Claim 9 (depends on 1) The receiver of claim 1, wherein the signal of the battery that indicates a charge level of the battery is a voltage signal of the battery; and determining that a relationship between the DC charging signal and the signal of the battery satisfies a predetermined criterion comprises: determining a target charging voltage based on the voltage signal of the battery; and determining that a voltage level of the DC charging signal is less than the target charging voltage. ### Claim 10 (depends on 1) The receiver of claim 1, wherein the signal of the battery that indicates a charge level of the battery is a current signal of the battery; and determining that a relationship between the DC charging signal and the signal of the battery satisfies a predetermined criterion comprises: determining a target battery current and a threshold voltage level; determining that a current level of the current signal of the battery is less than the target battery current; and determining that a voltage level of the DC charging signal is less than the threshold voltage level. ### Claim 11 (depends on 1) The receiver of claim 1, wherein generating a control signal to adjust the AC signal comprises generating a control signal to adjust the magnetic field. ### Claim 12 (depends on 11) The receiver of claim 11, wherein: the conversion circuit comprises one or more switches; and the controller is further configured to provide, to a transmitter, the control signal to adjust the magnetic field by generating a signal to change a state of one or more switches of the conversion circuit. ### Claim 13 (depends on 11) The receiver of claim 11, further comprising: a communication module configured to electronically communicate with a transmitter; and wherein the controller is further configured to provide, to the communication module, the control signal to adjust the magnetic field. ### Claim 14 A wireless charging system comprising: a transmitter configured to generate a magnetic field; and a receiver comprising: an inductive coil configured to generate an AC signal in the presence of the magnetic field; a conversion circuit configured to convert the AC signal generated by the inductive coil to a DC output signal, wherein the voltage level of the DC output signal is a function of one or more characteristics of the AC signal generated by the inductive coil; a charging circuit configured to: convert the DC output signal to a DC charging signal, wherein the voltage level of the DC charging signal has a fixed relationship to the voltage level of the DC output signal and the voltage level of the DC charging signal is less than the voltage level of the DC output signal; and provide the DC charging signal to a battery; and a controller configured to: measure a signal of the battery that indicates a charge level of the battery; based on the signal of the battery, determine that a relationship between the signal of the battery and the DC charging signal satisfies a predetermined criterion; and based on determining that the relationship between the DC charging signal and the signal of the battery satisfies the predetermined criterion, generate a control signal to adjust the magnetic field; wherein the receiver is configured to provide the control signal to adjust the magnetic field to the transmitter. ### Claim 15 (depends on 14) The system of claim 14, wherein: the signal of the battery that indicates a charge level of the battery is a voltage signal of the battery; and determining that a relationship between the DC charging signal and the signal of the battery satisfies a predetermined criterion comprises: determining a target charging voltage based on the voltage signal of the battery; and determining that a voltage level of the DC charging signal is less than the target charging voltage. ### Claim 16 (depends on 14) The system of claim 14, wherein: the signal of the battery that indicates a charge level of the battery is a current signal of the battery; and determining that a relationship between the DC charging signal and the signal of the battery satisfies a predetermined criterion comprises: determining a target battery current and a threshold voltage level; determining that a current level of the current signal of the battery is less than the target battery current; and determining that a voltage level of the DC charging signal is less than the threshold voltage level. ### Claim 17 (depends on 14) The system of claim 14, wherein: the conversion circuit further comprises one or more switches; and the receiver is configured to provide the control signal to adjust the magnetic field to the transmitter by changing a state of one or more of the switches of the conversion circuit. ### Claim 18 (depends on 14) The system of claim 14, wherein: the receiver further comprises: a communication module configured to electronically communicate with the transmitter; and the receiver is configured to provide the control signal to adjust the magnetic field to the transmitter by providing the control signal to adjust the magnetic field to the communication module. ### Claim 19 A method for wirelessly charging a battery, the method comprising: measuring, by a controller, a signal of the battery that corresponds to a charge level of the battery; receiving, by the controller, a signal representing a characteristic of a DC charging signal, wherein the DC charging signal is generated by a receiver, the receiver comprising: an inductive coil configured to generate an AC signal in the presence of a magnetic field; a conversion circuit configured to convert the AC signal generated by the inductive coil to a DC output signal, wherein a voltage level of the DC output signal is a function of one or more characteristics of the AC signal generated by the inductive coil; a charging circuit configured to: convert the DC output signal to the DC charging signal, wherein a voltage level of the DC charging signal has a fixed relationship to the voltage level of the DC output signal and the voltage level of the DC charging signal is less than the voltage level of the DC output signal; and provide the DC charging signal to the battery; and based on the signal of the battery and the signal representing the characteristic of the DC charging signal, determining, by the controller, that a relationship between the DC charging signal and the signal of the battery satisfies a predetermined criterion; and based on determining that the relationship between the DC charging signal and the signal of the battery satisfies the predetermined criterion, generating, by the controller a control signal to adjust the AC signal. ### Claim 20 (depends on 19) The method of claim 19, wherein the signal representing a characteristic of a DC charging signal comprises a signal representing a voltage level of a DC charging signal.