Abstract: A contactless power transmission apparatus includes a secondary device that includes a resonant circuit including a second transmitter coil that transmits and receives electric power to and from a first transmitter coil included in a primary device and a resonant capacitor connected in parallel to the second transmitter coil, a second converter circuit connected to the resonant circuit to convert alternating current power flowing through the resonant circuit to direct current power and convert direct current power to alternating current power flowing through the resonant circuit, a coil connected in series to the second transmitter coil between the resonant circuit and the second converter circuit, and a capacitor connected in series to the second transmitter coil between the second transmitter coil and the second converter circuit.

Abstract: Provided is a transformer (1), which includes: a core (10) which forms a magnetic circuit and has a middle leg (10a) and a plurality of side legs (10b, 10c) branched from the middle leg (10a); primary windings (11) respectively wound around a first winding leg (10a) and a second winding leg (10b), which are selected from the middle leg (10a) and the side legs (10b, 10c); and a secondary winding (12) wound around either of the first winding leg (10a) or the second winding leg (10b), wherein a first magnetic flux generated by the primary windings (11) from the first winding leg (10a) and a second magnetic flux generated by the primary windings (11) from the second winding leg (10b) differ from each other by a predetermined value or more at a position at which the fluxes do not intersect with the secondary winding (12).

Abstract: A power transmission device of this noncontact power supply apparatus has a transmission coil for supplying power to a power reception device, and a power supply circuit that supplies AC power to the transmission coil. A power reception device of the noncontact power supply apparatus has a reception coil for receiving power from the power transmission device, a variable capacity circuit that is connected to the reception coil in parallel and that can adjust capacitance, a resonance circuit that resonates with a frequency corresponding to the inductance of the reception coil and the capacitance of the variable capacity circuit, a voltage detection circuit that detects an output voltage from the resonance circuit, and a control circuit that controls the capacitance of the variable capacity circuit according to the output voltage.

Abstract: A power receiver device a noncontact power supply apparatus short-circuits a resonance suppressing coil provided so as to be electromagnetically coupled to a receiver coil and notifies a power transmitter device of an output voltage abnormality when a measured value of output voltage becomes equal to or greater than an upper limit threshold, the measured value of output voltage being obtained by rectifying power received via a resonance circuit including a receiver coil configured to receive power from a transmitter coil of the power transmitter device and a resonance capacitor connected in parallel with the receiver coil. Upon receipt of the notification of the output voltage abnormality, the power transmitter device changes at least one of a voltage and switching frequency of AC power applied to the transmitter coil.

Abstract: A contactless power transmission apparatus includes a transmitter that includes a transmitter coil that supplies electric power to a receiver and a power supply circuit that supplies alternating current power to the transmitter coil. The receiver includes a resonant circuit including a receiver coil that receives electric power from the transmitter and a resonant capacitor connected in series to the receiver coil, a rectifier circuit that rectifies electric power output from the resonant circuit, and a coil connected in parallel to the resonant circuit between the resonant circuit and the rectifier circuit.

Abstract: A contactless power transmission apparatus includes a receiver that includes a resonant circuit that receives electric power from a transmitter. The receiver causes, in response to a measurement value of an output voltage of electric power output from the resonant circuit being out of a predetermined allowable range of voltages, a short circuit to short-circuit the resonant circuit and transmits determination information indicating that the contactless power transmission apparatus is not outputting a constant voltage. In response to the determination information, the transmitter in the contactless power transmission apparatus detects a switching frequency of alternating current power to be supplied to a transmitter coil from a power supply circuit at which the contactless power transmission apparatus outputs a constant voltage in accordance with a measurement value of a current through the transmitter coil.

Abstract: A contactless power transmission apparatus includes a receiver that includes a resonant circuit including a receiver coil that receives electric power from a transmitter coil included in a transmitter and a resonant capacitor connected in parallel to the receiver coil. The receiver outputs, through an output coil having fewer turns than the receiver coil and a coil connected to the output coil, electric power received by the resonant circuit and rectifies the output power with a rectifier circuit. The transmitter includes a control circuit that controls a voltage and a switching frequency of alternating current power to be supplied to the transmitter coil from a power supply circuit to allow the contactless power transmission apparatus to continuously perform a constant voltage output operation.

Abstract: A non-contact feeding device has a power transmission device, and a power receiving device to which power is transmitted from the power transmission device in a non-contact manner. The power transmission device includes a transmission coil configured to supply the power to the power receiving device, a power supply circuit configured to supply AC power to the transmission coil and to be capable of adjusting at least one of a switching frequency and voltage of the AC power supplied to the transmission coil, a first communicator configured to receive an output voltage abnormal signal from the power receiving device, and a control circuit configured to change at least one of the switching frequency and the voltage of the AC power supplied from the power supply circuit to the transmission coil when the first communicator receives the output voltage abnormal signal.

Abstract: A power reception device 3 of a noncontact power supply apparatus 1 has a resonance circuit 20 that resonates at a first frequency, a voltage detection circuit 27 that measures an output voltage from the resonance circuit 20 and calculates a measured value of the output voltage, and a transmitter 28 that transmits a signal including information about the measured value of the output voltage to a power transmission device 2.

Abstract: A power transmission device of this noncontact power supply apparatus has a transmission coil for supplying power to a power reception device, and a power supply circuit that supplies AC power to the transmission coil. A power reception device of the noncontact power supply apparatus has a reception coil for receiving power from the power transmission device, a variable capacity circuit that is connected to the reception coil in parallel and that can adjust capacitance, a resonance circuit that resonates with a frequency corresponding to the inductance of the reception coil and the capacitance of the variable capacity circuit, a voltage detection circuit that detects an output voltage from the resonance circuit, and a control circuit that controls the capacitance of the variable capacity circuit according to the output voltage.

Abstract: In a non-contact power supply device, a power reception device includes a first resonant circuit that resonates at a first frequency, a voltage detection circuit that measures an output voltage from the first resonant circuit to obtain a measurement value of the output voltage, and a transmitter that transmits a signal including information representing the measurement value to a power transmission device. The power transmission device includes a second resonant circuit that resonates at a second frequency lower than the first frequency, a power supply circuit that supplies AC power having an adjustable switching frequency to the second resonant circuit, a receiver that receives the signal including the information representing the measurement value, and a control circuit that controls the switching frequency in accordance with the measurement value, such that the second resonant circuit and the power supply circuit continue a soft switching operation.

Abstract: A power transmission device of the non-contact feeding device includes the transmission coil that supplies power to a power receiving device, a power supply circuit that supplies AC power obtained by boosting or stepping down the input voltage to the transmission coil, a voltage detection circuit that measures the voltage input to the power supply circuit, and a control circuit that controls a degree of boosting or step-down with respect to the input voltage by the power supply circuit according to the input voltage measured. The power receiving device includes a resonance circuit including a receiving coil that receives the power from the power transmission device and a resonance capacitor that resonates with the receiving coil according to the power from the power transmission device and a rectifier circuit that rectifies the power output from the resonance circuit.

Abstract: A non-contact feeding device has a power transmission device, and a power receiving device to which power is transmitted from the power transmission device in a non-contact manner. The power transmission device includes a transmission coil configured to supply the power to the power receiving device, a power supply circuit configured to supply AC power to the transmission coil and to be capable of adjusting at least one of a switching frequency and voltage of the AC power supplied to the transmission coil, a first communicator configured to receive an output voltage abnormal signal from the power receiving device, and a control circuit configured to change at least one of the switching frequency and the voltage of the AC power supplied from the power supply circuit to the transmission coil when the first communicator receives the output voltage abnormal signal.

Abstract: Provided is a transformer (1), which includes: a core (10) which forms a magnetic circuit and has a middle leg (10a) and a plurality of side legs (10b, 10c) branched from the middle leg (10a); primary windings (11) respectively wound around a first winding leg (10a) and a second winding leg (10b), which are selected from the middle leg (10a) and the side legs (10b, 10c); and a secondary winding (12) wound around either of the first winding leg (10a) or the second winding leg (10b), wherein a first magnetic flux generated by the primary windings (11) from the first winding leg (10a) and a second magnetic flux generated by the primary windings (11) from the second winding leg (10b) differ from each other by a predetermined value or more at a position at which the fluxes do not intersect with the secondary winding (12).

Abstract: A switching power supply unit of the present invention a timing generating circuit (121) which receives a first control signal formed by a rectifier-transistor driving circuit (104), forms a second control signal based on the first control signal, and supplies the second control signal to a control electrode of the rectifier transistor (113). The first control signal is synchronized with the switching operation of a half-bridge circuit (102), and the second control signal exceeds a threshold voltage of a rectifier transistor (113) at a timing substantially equal to the timing that one edge of the first control signal is generated and falls below the threshold voltage of the rectifier transistor (113) at a timing earlier by predetermined time than the timing that the other edge of the first control signal is generated.

Abstract: A switching power supply unit of the present invention a timing generating circuit (121) which receives a first control signal formed by a rectifier-transistor driving circuit (104), forms a second control signal based on the first control signal, and supplies the second control signal to a control electrode of the rectifier transistor (113).

Abstract: A multi-stage DC—DC converter is provided that utilizes multiple loops in the control system to perform stable operation. The multi-stage DC—DC converter includes: a first DC—DC converter, a second DC—DC converter provided as a latter stage to said first DC—DC converter and a control circuit that controls the switching operation performed by said first DC—DC converter based on at least the output voltage of said first DC—DC converter and the output voltage of said second DC—DC converter.

Abstract: A switching power supply unit of the present invention a timing generating circuit (121) which receives a first control signal formed by a rectifier-transistor driving circuit (104), forms a second control signal based on the first control signal, and supplies the second control signal to a control electrode of the rectifier transistor (113). The first control signal is synchronized with the switching operation of a half-bridge circuit (102), and the second control signal exceeds a threshold voltage of a rectifier transistor (113) at a timing substantially equal to the timing that one edge of the first control signal is generated and falls below the threshold voltage of the rectifier transistor (113) at a timing earlier by predetermined time than the timing that the other edge of the first control signal is generated.

Abstract: A multi-stage DC-DC converter is provided that utilizes multiple loops in the control system to perform stable operation. The multi-stage DC-DC converter includes: a first DC-DC converter, a second DC-DC converter provided as a latter stage to said first DC-DC converter and a control circuit that controls the switching operation performed by said first DC-DC converter based on at least the output voltage of said first DC-DC converter and the output voltage of said second DC-DC converter.

Abstract: A DC/DC converter is provided that includes a switch device for converting a DC voltage into an AC voltage, a piezoelectric transformer for changing the AC voltage and a current doubler type rectification-smoothing device, which includes a first diode, a second diode, a first inductor, a second inductor, and a capacitor. The piezoelectric transformer has one output terminal connected to a cathode of the first diode and to one terminal of the first inductor, and the other output terminal connected to a cathode of the second diode and to one terminal of the second inductor. Anodes of the first and the second diodes are respectively grounded. The other terminal of the first inductor is connected at a predetermined connection point to the other terminal of the second inductor. The connection point is connected to one terminal of the capacitor, whose other terminal is grounded.