Abstract: A non-contact power transmission apparatus is disclosed. The non-contact power transmission apparatus includes an AC power source, a primary coil, a primary side resonance coil, a secondary side resonance coil, a secondary coil, a voltage measuring section, and a distance calculating section. AC voltage of the AC power source is applied to the primary coil. A load is connected to the secondary coil. The voltage measuring section measures the voltage of the primary coil. The distance calculating section calculates the distance between the primary side resonance coil and the secondary side resonance coil based on the voltage measured by the voltage measuring section.

Abstract: A non-contact power transmission apparatus having an AC power source and a resonance system is disclosed. The resonance system has a primary coil connected to the AC power source, a primary side resonance coil, a secondary side resonance coil, a secondary coil, and a load connected to the secondary coil. The primary side resonance coil is separated from the primary coil in an axial direction by a first distance, and the secondary coil is separated from the secondary side resonance coil in the axial direction by a second distance. At least one of the first distance and the second distance is adjusted to be a distance that is determined in advance in accordance with the impedance of the load so that the power transmission efficiency is maintained at a proper value.

Abstract: A resonance type non-contact charging apparatus is disclosed. A charger of the apparatus receives the high frequency power from a secondary side resonance coil of the apparatus. A power ratio detecting section of the apparatus detects the ratio of the reflected power from a primary side resonance coil to the high frequency power source with respect to the output power from the high frequency power source to the primary side resonance coil. A stop control section of the apparatus stops the high frequency power source when the ratio detected by the power ratio detecting section becomes greater than or equal to a predetermined threshold value.

Abstract: A non-contact power transmission apparatus having a resonance system is disclosed. The resonance system includes a primary coil to which an alternating-current voltage from an alternating-current source is applied, a primary-side resonance coil, a secondary-side resonance coil, and a secondary coil to which a load is connected. The impedance of the primary coil is set such that the output impedance of the alternating-current source and the input impedance of the resonance system are matched to each other.

Abstract: A DC-AC converter for converting DC voltage to AC voltage. The converter includes a conversion circuit for converting DC voltage to voltage having a polarity corresponding to AC voltage. A filter circuit receives the converted voltage, smoothes the converted voltage, and outputs the smoothed voltage as AC voltage. A first switch operably connects the voltage conversion circuit and filter circuit. A second switch is arranged between input terminals of the filter circuit. An output current detection circuit detects overcurrent that is greater than a predetermined first threshold. When overcurrent that is greater than the first threshold is detected, the protection circuit stops the supply of power in the voltage conversion circuit, deactivates the first switch, and activates the second switch.

Abstract: A power supply apparatus that supplies voltage of a battery to a load is disclosed. The power supply apparatus includes a booster circuit connected to the battery and a power storage section, which temporarily stores the power output by the booster circuit. The power storage section is connected in parallel with the load.

Abstract: A ground detector includes a pair of lines, a first series circuit, a reference portion, a second series circuit, and a detection point. The first series circuit connects the lines to each other. The first series circuit includes first capacitors that are connected in series. The reference portion is connected to a portion of the first series circuit between two of the first capacitors for DC insulating the lines from the reference portion. The second series circuit connects the lines to each other. The second series circuit includes second capacitors that are connected in series. The detecting point is provided in the second series circuit. Each of the lines is connected to the detecting point through at least corresponding one of the second capacitors. The ground detector detects a change of impedance between the lines and the reference portion based on a change of potential of the detecting point with respect to potential of the reference portion.

Abstract: A power supply unit that allows a main battery and an auxiliary battery to be charged by a system power supply is disclosed. The first and second bridge circuits of the power supply unit are each formed of four switching elements. The transformer of the power supply unit has a primary winding connected to the first bridge circuit, and a secondary winding connected to the second bridge circuit. The DC/DC converter of the power supply unit allows the auxiliary battery to be connected to the first and second circuits. The controller of the power supply unit controls the switching elements of the first bridge circuit, the switching elements of the second bridge circuit, and the switching element of the DC/DC converter such that power that has been charged to the main battery is output as an AC voltage having voltage and frequency for electric appliances.

Abstract: A DC-AC converter directly converts DC voltage to AC voltage. A voltage conversion circuit receives DC voltage at a pair of first input terminals, converts the DC voltage to voltage having a polarity corresponding to the AC voltage, and outputs the converted voltage from a pair of first output terminals insulated from the pair of first input terminals. The filter circuit receives the converted voltage at a pair of second input terminals, smoothes the converted voltage, and outputs the smoothed voltage as an AC voltage from a pair of second output terminals. A first switch circuit is arranged between the pair of first output terminals of the voltage conversion circuit and the pair of second input terminals of the filter circuit to operably connect the voltage conversion circuit and the filter circuit. A second switch circuit is arranged between the second input terminals of the filter circuit.

Abstract: A method for driving a converter that converts DC voltage to AC voltage. A voltage conversion circuit has first input terminals and first output terminals insulated from the first input terminals. A filter circuit has second input terminals and second output terminals. A first switch circuit connects the first output and second input terminals. A second switch circuit connects the first switch circuit and the second input terminals. The method includes supplying the first input terminals with DC voltage, converting the DC voltage to AC voltage and supplying the converted voltage to the first output terminals, supplying the second input terminals with the converted voltage, stopping the supply of the converted voltage, and maintaining the first switch circuit or the second switch circuit in an activated state to output AC voltage from the second output terminals of the filter circuit.

Abstract: A device for converting AC voltage to DC voltage. The device includes an AC input circuit, a rectifier circuit, a first switch, and a second switch. The AC input circuit includes a pair of first input terminals to which AC current is input, a pair of first output terminals, and at least one inductance element arranged in a path extending from the first input terminals to the first output terminals. The rectifier circuit includes a pair of second input terminals, a pair of second output terminals from which DC current is output, a transformer connected to the second input terminals, and a rectifier arranged between the transformer and the second output terminals. The first switch is connected between the first output terminals and the second input terminals. The second switch is connected between the first output terminals.

Abstract: An inverter device has a DC/AC inverter section that converts input DC voltage into AC voltage with a rectangular wave and outputs the AC voltage. A duty cycle setting section sets a duty cycle for controlling turning on and off of a switching element of the DC-AC inverter section by a controller. The duty cycle setting section determines the duty cycle using a signal based on the value of the DC voltage and a charging curve determined by a CR circuit. Accordingly, regardless of changes in the input voltage, the effective value of the output voltage approximates to a theoretical value compared to the conventional art.

Abstract: A DC-AC converter for converting DC voltage to AC voltage. The converter includes a conversion circuit for converting DC voltage to voltage having a polarity corresponding to AC voltage. A filter circuit receives the converted voltage, smoothes the converted voltage, and outputs the smoothed voltage as AC voltage. A first switch operably connects the voltage conversion circuit and filter circuit. A second switch is arranged between input terminals of the filter circuit. An output current detection circuit detects overcurrent that is greater than a predetermined first threshold. When overcurrent that is greater than the first threshold is detected, the protection circuit stops the supply of power in the voltage conversion circuit, deactivates the first switch, and activates the second switch.

Abstract: A ground detector includes a pair of lines, a first series circuit, a reference portion, a second series circuit, and a detection point. The first series circuit connects the lines to each other. The first series circuit includes first capacitors that are connected in series. The reference portion is connected to a portion of the first series circuit between two of the first capacitors for DC insulating the lines from the reference portion. The second series circuit connects the lines to each other. The second series circuit includes second capacitors that are connected in series. The detecting point is provided in the second series circuit. Each of the lines is connected to the detecting point through at least corresponding one of the second capacitors. The ground detector detects a change of impedance between the lines and the reference portion based on a change of potential of the detecting point with respect to potential of the reference portion.

Abstract: A driver for a switching device has a plurality of driver circuits for driving the switching device and a control circuit. The control circuit selectively operates the driver circuits in response to a plurality of predetermined drive modes. Alternatively, a driver for a switching device has a driver circuit and a control circuit. The driver circuit is connected to a plurality of power sources. Each of the power sources has a different voltage. The control circuit selects one of the power sources for operating the driver circuit in response to a plurality of predetermined drive modes.

Abstract: A driver for a switching device has a plurality of driver circuits for driving the switching device and a control circuit. The control circuit selectively operates the driver circuits in response to a plurality of predetermined drive modes. Alternatively, a driver for a switching device has a driver circuit and a control circuit. The driver circuit is connected to a plurality of power sources. Each of the power sources has a different voltage. The control circuit selects one of the power sources for operating the driver circuit in response to a plurality of predetermined drive modes.

Abstract: A driver for a switching device has a plurality of driver circuits for driving the switching device and a control circuit. The control circuit selectively operates the driver circuits in response to a plurality of predetermined drive modes. Alternatively, a driver for a switching device has a driver circuit and a control circuit. The driver circuit is connected to a plurality of power sources. Each of the power sources has a different voltage. The control circuit selects one of the power sources for operating the driver circuit in response to a plurality of predetermined drive modes.

Abstract: A transformer has a primary winding and a secondary winding. A center tap of the primary winding is connected with one end of a d.c. power supply. Both ends of the primary winding are connected to the drains of transistors (Q1) and (Q2) that constitute switching elements, respectively. Also, the sources of the transistors (Q1) and (Q2) are connected to the other ends of the d.c. power supply. The gates of the transistors (Q1) and (Q2) are connected to one ends of gate resistors (R1) and (R2), respectively. The other ends of the gate resistors (R1) and (R2) are connected to a control circuit, and the resistance of the gate resistor (R2) is larger than the resistance of the gate resistor (R1).

Abstract: A transformer has a primary winding and a secondary winding. A center tap of the primary winding is connected with one end of a d.c. power supply. Both ends of the primary winding are connected to the drains of transistors (Q1) and (Q2) that constitute switching elements, respectively. Also, the sources of the transistors (Q1) and (Q2) are connected to the other ends of the d.c. power supply. The gates of the transistors (Q1) and (Q2) are connected to one ends of gate resistors (R1) and (R2), respectively. The other ends of the gate resistors (R1) and (R2) are connected to a control circuit, and the resistance of the gate resistor (R2) is larger than the resistance of the gate resistor (R1).

Abstract: A high frequency switching is performed while FETs 21 and 24, and FETs 22 and 23 are alternately switched on according to FET switching signals L and R. For example, a high frequency drive signal F is provided for transistors 31 and 32 through an OR gate 30 while FETs 22 and 23 are in an ON state, thereby alternately turning on and off the transistors 31 and 32 and driving the FET 22 at a high frequency. Similarly, a high frequency drive signal F is provided for two transistors through an OR gate while FETs 21 and 24 are in an ON state, thereby alternately turning on and off the two transistors and driving the FET 24 at a high frequency.