# US 2015/0145346 A1 · Contactless power transmission circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0145346 A1 - Document ID: US20150145346A1 - Status: Published application - Kind: A1 - Application number: 14/555,188 - Filed: 2014-11-26 - Published: 2015-05-28 - Earliest claimed: 2013-11-28 - Assignees: TDK Corporation - Applicants: TDK Corporation - Inventors: Masahide OHNISHI; Takeshi KAMONO - Web page: https://patentgrep.com/patent/US20150145346A1 ## CPC - H02J 50/12: of the resonant type - H01F 38/14: Inductive couplings - H02J 50/90: involving detection or optimisation of position, e.g. alignment - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract The present invention provides a contactless power transmission circuit which is capable of narrowing a fluctuation extent of an output voltage output by a over receiving coil via a rectifier circuit. The contactless power transmission circuit controls a period of an alternating voltage output from a driving circuit based on a smaller one of either of a first command value and a second command value. Here, the first command value is one based on a difference between a detected value of the output voltage from the rectifier circuit and a target value. The second command value is one calculated based on a difference between a detected value of a transmission current flowing through the power transmitting coil and a target value. ## Claims ### Claim 1 A contactless power transmission circuit for transmitting a power via a magnetic field from a power transmitting coil to a power receiving coil, comprising: a driving circuit for supplying an alternating voltage to the power transmitting coil, a rectifier circuit for rectifying a voltage generated in the power receiving coil with a magnetic field generated by the power transmitting coil, a transmission current detecting circuit for detecting a transmission current flowing through the power transmitting coil, an output voltage detecting circuit for detecting an output voltage of the rectifier circuit, and a control circuit for controlling a period of the alternating voltage output from the driving circuit, wherein the control circuit is set to calculate a first command value and a second command value which are command values for the period of the alternating voltage, and use a smaller one of either of the first command value and the second command value as a command value for the period of the alternating voltage, the first command value is a command value based on a difference between a detected value of the output voltage detected by the output voltage detecting circuit and a target value of the output voltage, and the second command value is a command value calculated based on a difference between a detected value of the transmission current detected by the transmission current detecting circuit and a target value of the transmission current. ### Claim 2 (depends on 1) The contactless power transmission circuit of claim 1, wherein, the target value of the transmission current is set to a maximum allowable current value of the power transmitting coil. ### Claim 3 (depends on 1) The contactless power transmission circuit of claim 1, further comprising: an output current detecting circuit for detecting an output current of the rectifier circuit, wherein the control circuit sets a target value of the output voltage based on a detected value of the output current which is detected by the output current detecting circuit and uses the target value to calculate the first command value. ### Claim 4 (depends on 3) The contactless power transmission circuit of claim 3, wherein, when the output current of the rectifier circuit exceeds a predetermined current value, the target value of the output voltage is set in such a way that an output power of the rectifier circuit is at a certain value or the output current of the rectifier circuit is at a certain value. ### Claim 5 A contactless power transmission circuit for transmitting a power via a magnetic field from a power transmitting coil to a power receiving coil, comprising: a driving circuit for supplying an alternating voltage to the power transmitting coil, a rectifier circuit for rectifying a voltage generated in the power receiving coil with a magnetic field generated by the power transmitting coil, a transmission current detecting circuit for detecting a transmission current flowing through the power transmitting coil, an output voltage detecting circuit for detecting an output voltage of the rectifier circuit, and a control circuit for controlling a period of the alternating voltage output from the driving circuit, wherein the control circuit comprises a target voltage setter for outputting a target value of the output voltage, a target current setter for outputting a target value of the transmission current, a first subtracter for subtracting an output of the output voltage detecting circuit from an output of the target voltage setter, a second subtracter for subtracting an output of the transmission current detecting circuit from an output of the target current setter, a first PFM controller which is connected to an output of the first subtracter and outputs a first command value which is a command value for the period of the alternating voltage, a second PFM controller which is connected to an output of the second subtracter and outputs a second command value which is a command value for the period of the alternating voltage, a comparator which connects an output of the first PFM controller to an inverted input and connects an output of the second PFM controller to a non-inverted input, a multiplexer which connects the output of the first PFM controller and the output of the second PFM controller to an input and connects an output of the comparator to a selection control input, wherein the multiplexer is set to select the output of the first PFM controller when the output of the comparator is a high level, and to select the output of the second PFM controller when the output of the comparator is a low level. ### Claim 6 (depends on 5) The contactless power transmission circuit of claim 5, wherein, the target current setter outputs a maximum allowable current value of the power transmitting coil as the target value of the transmission current. ### Claim 7 (depends on 5) The contactless power transmission circuit of claim 5, further comprising: an output current detecting circuit for detecting an output current of the rectifier circuit, wherein the target voltage setter outputs the target value of the output voltage based on a detected value of the output current which is detected by the output current detecting circuit. ### Claim 8 (depends on 7) The contactless power transmission circuit of claim 7, wherein, when the output current of the rectifier circuit exceeds a predetermined current value, the target voltage setter adjusts and outputs the target value of the output voltage in such a way that an output power of the rectifier circuit is at a certain value or a way that the output current of the rectifier circuit is at a certain value. ### Claim 9 (depends on 2) The contactless power transmission circuit of claim 2, further comprising: an output current detecting circuit for detecting an output current of the rectifier circuit, wherein the control circuit sets a target value of the output voltage based on a detected value of the output current which is detected by the output current detecting circuit and uses the target value to calculate the first command value. ### Claim 10 (depends on 6) The contactless power transmission circuit of claim 6, further comprising: an output current detecting circuit for detecting an output current of the rectifier circuit, wherein the target voltage setter outputs the target value of the output voltage based on a detected value of the output current which is detected by the output current detecting circuit.