Abstract: A switching power-supply circuit includes a second rectifying/smoothing circuit arranged to generate a second output voltage by rectifying and smoothing the output of a second secondary winding, and the second rectifying/smoothing circuit includes a second rectifier circuit and a capacitor, connected to the second secondary winding. A second switching control circuit operates in response to an alternating-current winding voltage occurring in the second secondary winding, and includes a time constant circuit causing a switch mechanism connected to the control terminal of a rectifier switch element to operate, and a second feedback circuit arranged to detect and feed back the second output voltage to the time constant circuit.

Abstract: In a switching power supply apparatus, a switching element is turned on/off to intermittently conduct current input via an inductor. Current input during a period in which the switching element is turned off is supplied to an electrolytic capacitor via a conduction path. A rectifier diode is provided in the conduction path to face toward the electrolytic capacitor. An inductor is provided in the conduction path to be connected in series with the rectifier diode. A high speed diode has a reverse recovery time shorter than the reverse recovery time of the rectifier diode, and is connected in parallel with the inductor to face toward the electrolytic capacitor.

Abstract: A switching power-supply circuit includes a transformer, a first switching element, a first rectifying/smoothing circuit generating a first output voltage by rectifying and smoothing the output of a first secondary winding, a second rectifying/smoothing circuit generating a second output voltage by rectifying and smoothing the output of a second secondary winding, a first feedback circuit generating a feedback signal according to the first output voltage, and a first switching control circuit. When the voltage of the second secondary winding is greater than the second output voltage and the second output voltage is less than the voltage of a reference-voltage circuit, a second rectifier circuit turns on a rectifier switch element, and stabilizes the second output voltage by controlling the number of pulses per unit time in a pulse current flowing through the second rectifier circuit.

Abstract: A power transmitting unit-side resonance circuit including a resonance capacitor connected in series to a power transmitting coil and a power receiving unit-side resonance circuit including a resonance capacitor connected in series to a power receiving coil are caused to resonate with each other so that each resonance circuit resonates. With this, power is transmitted between the power transmitting coil and the power receiving unit making use of magnetic field resonance coupling and electric field resonance coupling. By making use of resonance, only effective power is transmitted from the power transmitting unit side to the power receiving unit side, while reactive power that is reflected is reserved as resonance energy in each resonance circuit.

Abstract: A switching power supply apparatus includes an isolated converter with efficiency characteristics in which power conversion efficiency of a rated load is higher than power conversion efficiency of a light load and that converts power-supply voltage into direct-current voltage to output the direct-current voltage, a secondary battery that stores the direct-current voltage output from the isolated converter; a voltage detector that detects an amount of charge in the secondary battery; and a controller that switches driving and stopping of the isolated converter on the basis of the detected amount of charge.

Abstract: A switching power supply apparatus includes an isolated converter that has efficiency characteristics in which power conversion efficiency at a rated load is higher than power conversion efficiency at a light load and that converts power-supply voltage into direct-current voltage to output the direct-current voltage; an FET that switches supply and shutoff of the power-supply voltage to the isolated converter; a secondary battery that stores the direct-current voltage output from the isolated converter; a voltage detector that detects an amount of charge in the secondary battery; and a controller that switches the FET on the basis of the amount of charge in the secondary battery.

Abstract: In a switching power supply device, a voltage of a counter electromotive force induced in a drive winding as a high side switching element is turned off is output to a ZT terminal of a switching control IC, and thus an OUT terminal of the switching control IC is brought to a high level, and thus a low side switching element is turned on. A constant current circuit charges a capacitor with a constant current through a voltage at the OUT terminal. A comparator in the switching control IC inverts the voltage at the OUT terminal to a low level upon a voltage at an IS terminal exceeding a voltage at an FB terminal. Thus, an on time of the low side switching element is controlled in accordance with a voltage output to the FB terminal, and an output voltage Vo is turned into a constant voltage.

Abstract: In a switching power supply apparatus, when it is detected at time t1 that a voltage Vis has exceeded a first threshold Vth1, a timer counting a period of time T1 is started, and the number times the input voltage Vis does not exceed Vth1 is started to be counted. When the timer expires before the count reaches a predetermined number, a first overcurrent protection operation is performed. When it is detected at time t2 that Vis has exceeded a second threshold Vth2, a second overcurrent protection operation is immediately performed. As a result, appropriate overcurrent protection is performed in accordance with the operating state of a load.

Abstract: A power-transmission-unit-side resonant circuit includes a resonant capacitor connected in series with a power transmission coil and a power-reception-unit-side resonant circuit including a resonant capacitor connected in series with a power reception coil resonate with each other to cause sympathetic vibration. This allows power to be transferred using two kinds of coupling via the magnetic field and the electric field between the power transmission coil and the power reception coil. Also, operation is performed at a switching frequency that is higher than a specific resonant frequency of the entire multi-resonant circuit, such that a ZVS operation is performed. As a result, a switching loss is reduced by a large amount and a highly efficient operation is performed thus enabling a power transfer system with a reduced size and an increased power conversion efficiency to be provided.

Abstract: A power conversion circuit includes multiple input-side capacitors connected in series between input terminals; series circuits composed of high-side switching elements and low-side switching elements connected in parallel to the multiple input-side capacitors; and output-side capacitors connected between nodes and a node. The circuit further includes an output-side inductor connected to the node and a controller that alternately turns on and off the high-side switching elements and the low-side switching elements. Each of the low-side switching elements and the high-side switching elements is a MOSFET and causes current to flow from the low side to the high side using a body diode. Accordingly, there is provided a power conversion circuit that has high conversion efficiency and that is capable of realizing reduction in size, a power transmission system, and a power conversion system.

Abstract: In a switching power supply device, a partition portion that includes a slit divides a winding portion of a bobbin. A primary winding of a transformer is wound to a height h1 in a first section, and a secondary winding is wound to a height h2 in a second section. A low side drive winding and a high side drive winding are wound around the primary winding to a height h3 with the high side drive winding being located toward the secondary winding.

Abstract: A power transmitter and a power receiver are disposed with a space provided therebetween, and a power transmission device produces an electromagnetic field that periodically changes using the AC current in a space and forms a vibrating electromagnetic resonance field in which the space itself has energy. By obtaining electrical energy from the resonance field, a power reception device produces a resonance current, and a new electromagnetic resonance field is formed by the resonance current. The power transmission device or the power reception device is constituted of a conductor having a Peano curve shape that covers a surface having a given spread by passing through all regions obtained by dividing the surface having a given spread without intersecting with itself, and the electromagnetic field energy of a space in the periphery of the fractal-shaped device is increased.

Abstract: A power transmitter and a power receiver are arranged with a space therebetween. A power transmitting device generates a resonant current by taking out electric energy from a DC power supply through an operation of a power transmitting switch circuit, directly creating, in a space, by using the resonant current, an electromagnetic field that periodically changes at a switching frequency, and forms an electromagnetic resonance field in which the space itself has energy and vibrates. A power receiving device generates a resonant current by obtaining electric energy from the resonance field and forms a new electromagnetic field on the basis of this resonant current. The power transmitting device or the power receiving device, when viewed as a geometric figure, is a fractal-shaped device formed of a line conductor pattern in which a portion is similar to the whole, and increases electromagnetic field energy in a space surrounding the fractal-shaped device.

Abstract: A power transmitter coil, a power transmitter circuit, and a direct-current power source constitute a power transmitter unit. Further, a power receiver coil, a power receiver circuit, and a load constitute a power receiver unit. Further, a resonator coil and a resonator circuit constitute a resonator unit. In the power transmitter unit, electric energy of the direct-current power source is directly converted into electromagnetic energy, a resonant field is expanded by making resonance currents of the same frequency to flow in the power transmitter coil and the resonator coil, and in the power receiver unit, electromagnetic energy of the resonant field is directly converted into electric energy, thereby transmitting electric power from the power transmitter unit to the power receiver unit.

Abstract: In a switching control circuit, a length of a soft start period is set in accordance with a time constant of an external circuit connected to a soft start terminal of a switching control IC. A current flowing through a switching element is detected at a current detection terminal. When the value of the current exceeds a first predetermined current value, a second overcurrent protection function is performed, so that a switching operation is stopped. When the value of the current exceeds a second predetermined current value, a second overcurrent protection function is performed, so that the switching element is quickly turned off and a current peak value is limited. On the basis of a voltage at the soft start terminal after the soft start period has elapsed, one of the setting and non-setting of the first overcurrent protection function is selected.

Abstract: A primary side resonant circuit is formed by a primary side resonant inductor and a primary side resonant capacitor, and secondary side resonant circuits are formed by secondary side resonant inductors and secondary side resonant capacitors. Mutual inductances are formed equivalently through magnetic field resonant coupling between a primary winding and secondary windings, and a multi-resonant circuit that includes two or more LC resonant circuits is formed by a primary side circuit and a secondary side circuit. Electric power is transmitted from the primary side circuit to the secondary side circuit; resonant energy that is not transmitted from the primary winding and, of energy which the secondary winding has received, resonant energy that is not supplied to an output are each retained in the multi-resonant circuit; and, at the secondary side, the resonant energy is retained in a current path in which a rectifying element is not formed in series.

Abstract: In a switching power supply device with reduced size and increased power conversion efficiency, a first resonant circuit including a series resonant inductor and a series resonant capacitor, and a second resonant circuit including a series resonant inductor and a series resonant capacitor, are caused to resonate with each other to cause sympathetic vibration of each resonant circuit, such that transmission is performed by utilizing both magnetic field coupling and electric field coupling between a primary winding and a secondary winding. Operation at a switching frequency higher than a specific resonant frequency of an overall multi-resonant circuit allows a ZVS operation to be performed, enabling a significant reduction in switching loss and high-efficiency operation.

Abstract: A power sending loop coil disposed in a power sending device takes out electric energy from DC power and generates periodically-varying electromagnetic field resonance energy in a space. A power receiving loop coil disposed in a power receiving device takes out, as electric energy, the periodically-varying electromagnetic field resonance energy from the space and supplies electric power to a load. The power sending loop coil and the power receiving loop coil are coupled to each other through electromagnetic field resonant coupling, whereby electric power is wirelessly transferred from the power sending device to the power receiving device.

Abstract: An external circuit is connected to a polarity detection terminal of a switching control IC. An increased value of the voltage of a pulse signal input to the polarity detection terminal at the time of the activation of a power supply changes in response to this external circuit. Accordingly, owing to the external circuit connected to the polarity detection terminal, the validity/invalidity of a standby mode is set. When the standby mode is validated, a blanking frequency changes in response to the voltage of a feedback terminal, and a switching loss in a light load is reduced. Accordingly, a switching control circuit and a switching power supply apparatus are configured that are able to set the validity/invalidity of the standby mode or select the method of the standby mode without using a dedicated terminal.

Abstract: A primary side resonant circuit is formed by a primary side resonant inductor and a primary side resonant capacitor, and secondary side resonant circuits are formed by secondary side resonant inductors and secondary side resonant capacitors. Equivalent mutual inductances and equivalent mutual capacitances are formed through electromagnetic field resonant coupling between a primary winding and secondary windings, and a multi-resonant circuit including an LC resonant circuit formed in each of the primary side and the secondary side is formed. Electric power is transmitted from the primary side circuit to the secondary side circuit, and resonant energy that is not transmitted from the primary winding and, of energy which the secondary winding has received, resonant energy that is not supplied to an output are each retained in the multi-resonant circuit.