Omron Corporation

Chiba University

Taichi Mishima

Takeshi Uematsu

Shingo Nagaoka

Yuki Ito

Goro Nakao

Hiroo Sekiya

Yusuke Kawai

Ken Onozaka

Hiroaki Ota

A resonance-type power converter circuit includes: a resonance circuit including a first LC resonance circuit and a switching element, and outputting an output voltage or current to a load; a detector circuit detecting output information; an calculation controller searching for a maximum point in a characteristic of the output information at an operating frequency based on the detected output information, and determining an operating frequency corresponding to the searched maximum point; and a signal generator generating a drive control signal having the determined operating frequency, and controlling the frequency based on the drive control signal. The resonance circuit has a characteristic of output information at the operating frequency having a load independent point not depending on the load and corresponding to the maximum point and feeds back a drive control signal including the output information to the switching element and drives it at the load independent point by frequency control.

Resonance-type power converter circuit provided with resonance circuit including LC resonance circuit and switching element

A contactless power feed apparatushas a relay circuitrelaying power transmitted from a power transmission deviceto a power reception devicein a contactless manner. The power transmission devicehas: a transmission coiltransmitting AC power to the relay circuit. The relay circuithas: a first coil, electromagnetically coupled with the transmission coiland receiving the AC power from the transmission coil; a second coil, transmitting the AC power to the power reception device; and a resonant capacitor, resonating with the AC power supplied to the transmission coiltogether with the first and second coils. The power reception devicehas: a resonant circuit, having a reception coilreceiving AC power from the second coilby being electromagnetically coupled with the second coilof the relay circuit

Contactless power feed apparatus

A power reception deviceincludes: an estimation circuitestimating a load resistance of an entire contactless power feed apparatus; and a reception-side communicatortransmitting an estimated value of the load resistance of the entire contactless power feed apparatusto a power transmission device. The power transmission devicehas a power supply circuitsupplying AC power to a transmission coilsupplying power to the power reception device. The power transmission devicefurther includes a control circuitdecreasing an input/output gain of a transmission-side DC-DC converterincluded in the power supply circuitby a predetermined amount when the estimated value of the load resistance is less than a predetermined allowed lower limit, and maintaining or increasing the input/output gain when the estimated value of the load resistance is equal to or greater than the predetermined allowed lower limit.

Contactless power feed apparatus and power transmission method

A foreign matter detection device includes: a plurality of detection coils (-to-) between a transmission coil () of a power transmission device () and a reception coil () of a power reception device (), through which power is transmitted in a contactless manner; a plurality of capacitors (-to-) forming, for each of the detection coils, a resonance circuit together with the detection coil; a power supply circuit () supplying AC power having a predetermined frequency to each detection coil; and a detection circuit () detecting a voltage output from each detection coil and detecting a foreign matter entering between the transmission coil () and the reception coil () according to the voltage detected. Then, each detection coil is arranged to overlap by a predetermined amount that allows electromagnetic coupling between adjacent two of the detection coils (-to-) to be ignored.

Foreign matter detection device

A control circuit controls a power supply circuit to generate transmitting power having a frequency varying within a frequency range. The control circuit determines a stably transmitting frequency based on a detected output voltage of a power receiver apparatus, the stably transmitting frequency indicating a frequency of the transmitting power at which dependency of the output voltage on a load value of the power receiver apparatus is at least locally minimized within the frequency range. The control circuit determines a transmitting voltage based on the detected output voltage, the transmitting voltage indicating a voltage of the transmitting power at which the output voltage reaches a target voltage when generating transmitting power having the stably transmitting frequency. The control circuit controls the power supply circuit to generate transmitting power having the stably transmitting frequency and the transmitting voltage.

Contactless power transmission system capable of controlling power transmitter apparatus to stably supply load device with required power

A power transmitting apparatus included in a contactless power feeding apparatus includes a power supply circuit that supplies AC power having a predetermined drive frequency to a transmission coil for supplying power to a power receiving apparatus, a power receiving circuit that receives returning power transmitted from the power receiving apparatus, a control circuit that controls, according to a voltage of the returning power, the power supply circuit such that an output voltage of the power receiving apparatus is in a predetermined allowable range. Also, the power receiving apparatus includes a resonant circuit for receiving power via the transmission coil of the power transmitting apparatus, a rectifier circuit that rectifies power received via the resonant circuit, and a power transmitting circuit that transmits the returning power according to a voltage of power output from the rectifier circuit to the power transmitting apparatus.

Contactless power feeding apparatus

A first detector detects a value of a current or voltage generated by an auxiliary coil. A second detector detects a value of a current flowing through a power transmitting coil. A coupling coefficient estimator estimates a first coupling coefficient between the power transmitting coil and a power receiving coil, based on the value of the current or voltage generated by the auxiliary coil, and estimates a second coupling coefficient between the power transmitting coil and the power receiving coil, based on the value of the current flowing through the power transmitting coil. A control circuit controls a power supply circuit to stop power transmission to a power receiver apparatus when a difference between the coupling coefficients is greater than a threshold.

Contactless power transmission system for transmitting power from power transmitter apparatus to power receiver apparatus, and detecting foreign object

A detection circuit detects at least one of a value of a current flowing through a power transmitting coil, and a value of a current or voltage generated by an auxiliary coil. A control circuit determines a transmitting frequency based on the value detected by the detection circuit, the transmitting frequency at least locally minimizing load dependence. The control circuit determines a voltage for the transmitting power at which an output voltage of a power receiver apparatus is equal to a predetermined target voltage when generating the transmitting power having the transmitting frequency determined, and controls the power supply circuit to generate the transmitting power having the transmitting frequency and voltage determined.

Contactless power transmission system for transmitting power from power transmitter apparatus to power receiver apparatus, and supplying load device with desired voltage

A resonance oscillator circuit is provided to include first and second oscillators. The first oscillator includes a first LC resonator circuit and an amplifier element, and oscillates by shifting a phase of an output voltage with a predetermined phase difference and feeding the output voltage back to the amplifier element. The second oscillator oscillates by generating a gate signal, which has a frequency identical to that of the output voltage, and drives the amplifier element, by shifting the phase of the output voltage with the phase difference and feeding the gate signal back to an input terminal of the amplifier element, by using the amplifier element as a switching element and using the first oscillator as a feedback circuit. The phase difference is a value substantially independent of an inductance of the first LC resonator circuit and a load, to which the output voltage is applied.

Growing community of inventors

Kizugawa, Japan

Taichi Mishima