Sansha Electric Manufacturing Company, Limited

Toshikazu Fujiyoshi

Haruo Moriguchi

Kunio Karino

Kenji Morimoto

Kenzo Danjo

Hideo Ishii

Hajime Katsushima

Satoshi Yamamura

Tetsuro Ikeda

Toru Arai

Atsushi Kinoshita

Masayuki Ono

Masao Katooka

Satoshi Hamada

Masahiro Aoyama

Tetsurou Ikeda

Takashi Hashimoto

Hajime Yamamoto

Shigeru Okamoto

Kunio Shikata

Takeshi Omura

Atushi Kinoshita

A DC-DC converter includes a regeneration snubber circuit. The snubber circuit is connected in parallel with the secondary diode circuit and includes a series circuit of a discharge blocking diode, a snubber capacitor, and a switching element for regeneration connected in parallel with the discharge blocking diode. The DC-DC converter further includes a control unit which turns the switching element for regeneration on a predetermined time period after the timing of turning the primary side switching element off. The predetermined time period is set to approximately the time period during which the charge, accumulated in the snubber capacitor due to reverse recovery time when one of the secondary diodes has been turned off, discharges.

DC-DC converter including regeneration snubber circuit

This inverter circuit includes first and second switching elements and an output transformer which is provided with a first primary winding connected in series between said first and second switching elements, and also with a secondary winding for obtaining an output voltage. The inverter circuit is further provided with a first voltage supply, a second voltage supply, and a control unit. The first voltage supply applies voltage to said first switching element via said first primary winding. And the second voltage supply applies voltage to said second switching element via said second primary winding. The control unit turns said first switching element and said second switching element alternatingly ON and OFF. This inverter circuit also includes first and second regeneration snubber circuits for regenerating the charge charged into snubber capacitors.

Inverter circuit with controller for controlling switching elements based on a magnitude of output power

This DC-DC converter circuit includes: first and second switching elements (S, S); an output transformer (T) that includes a first primary winding (P) connected in series between the positive electrode sides of the first and second switching elements (S, S), a second primary winding (P) connected in series between their negative electrode sides, a secondary winding (S) for obtaining an output voltage, and tertiary windings (n, n); a first voltage source (C), connected between a first connection point at which the first primary winding (P) is connected to the second switching element (S) and the first switching element (S), that applies a voltage to the first switching element via the first primary winding; a second voltage source (C) connected to locations symmetric with those of the first voltage source (C); and a control unit (CT) that turns the first and second switching elements (S, S) alternatingly ON and OFF, and first and second regeneration snubber circuits (SN, SN) for regenerating the charge in snubber capacitors (C, C) to the voltage sources (C, C); and these regeneration snubber circuits (SN, SN) include third and fourth switching elements (S, S) driven by the output voltages of the tertiary windings (n, n).

DC-DC converter circuit

This inverter circuit includes two switching elements which are turned alternately ON and OFF, and a first primary winding connected in series between these switching elements, and also includes an output transformer having a secondary winding for obtaining an output voltage. This inverter circuit also includes a first voltage source and a second voltage source. The first voltage source applies a voltage to the first switching element via the first primary winding. And the second voltage source applies a voltage to the second switching element via the second primary winding. This inverter circuit also includes a regeneration snubber circuit for regenerating charge accumulated in a snubber capacitor. The regeneration snubber circuit includes a regeneration circuit including a voltage boost section which converts the primary side voltage of the output transformer to a predetermined voltage, which it outputs.

Current balanced push-pull inverter circuit with regeneration snubber circuit and voltage boost section

This inverter circuit includes first and second switching elements and an output transformer which has a first primary winding connected in series between the first switching element and the second switching element and a second primary winding for obtaining an output voltage. The inverter circuit also includes a first voltage source, a second voltage source, and a control unit. The first voltage source is connected between a first connection point at which the first primary winding is connected to the second switching element, and the first switching element, and applies a voltage to the first switching element via the first primary winding. And the second voltage source is connected between a second connection point at which the first primary winding is connected to the first switching element, and the second switching element, and applies a voltage to the second switching element via the first primary winding. The control unit alternately turns the first switching element and the second switching element ON and OFF. And this inverter circuit also may include first and second recovery snubber circuits for recovering electrical charge in snubber capacitors.

Current balanced push-pull inverter circuit

This current balanced push-pull type inverter circuit includes first and second switching elements, and an output transformer which includes a first primary winding and a second primary winding connected in series between said first and second switching elements, and also includes a secondary winding for obtaining an output voltage. This inverter circuit also includes a first voltage supply capacitor, a second voltage supply capacitor, and a control unit. A first snubber circuit, in which a first free wheel diode and first and second snubber capacitors are connected in series, is connected in inverse parallel to the first switching element. A first discharge resistor is connected between the first snubber capacitor and a first power supply capacitor, and a second discharge resistor is connected between the second snubber capacitor and a third power supply capacitor. And a second snubber circuit and discharge resistors are connected to the second switching element as well, in a similar manner.

Current balanced push-pull inverter circuit with snubber and discharge circuitry

An input-side rectifier (), a smoothing capacitor (), an inverter (), a transformer () and an output-side rectifier () operate together to convert an AC voltage supplied from an AC power supply to a DC voltage. The DC voltage is coupled through a DC-to-AC converter () to a workpiece () and a torch (). An auxiliary voltage supply () supplies the workpiece () and the torch () with a negative voltage for a short time following the transition of the AC voltage supplied to the workpiece () and the torch () from positive to negative. The negative voltage has a negative peak value larger than the negative peak value of the AC voltage supplied to the workpiece () and the torch (), and rapidly changes from the negative peak value. The auxiliary voltage supply () produces a DC voltage having a negative peak value larger than the negative peak value of the AC voltage supplied to the workpiece () and the torch (), by means of a transformer (), a rectifier () and a smoothing capacitor (). The smoothing capacitor () is coupled to the workpiece () and the torch () through a transistor () and a current-limiting resistor (). A differentiating circuit () is coupled in parallel with the current-limiting resistor (), and includes a resistor () having a smaller resistance value than the current-limiting resistor ().

Power supply apparatus

Capacitors () are connected in series across a DC power supply (). IGBTs () are connected in series across the DC power supply (), too. The IGBTs () are rendered conductive alternately. A transformer () is connected between the junction of the capacitors () and the junction of the IGBTs (). Snubber capacitors () are connected in parallel with the IGBTs (), respectively. Diodes () are connected in series with respective ones of the snubber capacitors () in such a manner that said snubber capacitors () can be charged when the IGBTs () are rendered nonconductive. A secondary winding (SA) of a transformer () is connected between the DC power supply () and the junction of the snubber capacitor () and the diode (), and converts a secondary voltage of the transformer () and returns the converted voltage to the DC power supply () when the IGBT () is conductive. A secondary winding (SB) of the transformer () is connected between the DC power supply () and the junction of the snubber capacitor () and the diode (), and converts a secondary voltage of the transformer () and returns the converted voltage to the DC power supply () when the IGBT () is conductive.

Metallic coils sheets ( ) are planar and include center windows ( ). Slits ( ) extend outward through the respective sheets from the windows. Connection terminals ( ) are provided on the sheets at locations facing across the respective slits. The metallic coil sheets are stacked, and adjacent ones of the stacked metallic coil sheets are electrically connected by means of the connection terminals. A core ( ) is disposed in the windows of the stacked metallic coil sheets. The metallic coil sheets are individually covered with an insulating coating.

Coil

A high-frequency large current handling transformer includes a stack of plural metal planar coil members with a window formed in a center portion of each of the planar coil member. A slit extends outward from the window in each planar coil member. First and second terminals are provided for each planar coil member at locations on opposite sides of the slit. An insulating sheet having a window formed in its center portion is disposed between adjacent ones of the planar coil members. Some of the planar coil members are connected in series to provide a higher-voltage side coil, and the remaining planar coil members are connected in parallel to provide a lower-voltage side coil. An 8-shaped high-frequency core is operatively combined with the coils.

High-frequency large current handling transformer

A conductor is wound around a magnetic core to form a plurality of conductor turns. The conductor turns are spaced from one another by a substantially equal spacing d. An insulating layer is disposed between the conductor turns and the magnetic core. An insulating member is wound around the magnetic core in such a manner as to be located in the spaces between and in contact with adjacent ones of the conductor turns.

A DC power supply apparatus includes a rectifier circuit which rectifies an input commercial AC voltage. The rectifier output voltage is smoothed in a smoothing capacitor. The DC voltage from the capacitor is converted to a high-frequency voltage in an inverter. The high-frequency voltage from the inverter is voltage-transformed by a transformer into a voltage-transformed, high-frequency voltage, which is then converted back into a DC voltage in a high-frequency-to-DC converter circuit. When an input commercial AC voltage is applied to the DC power supply apparatus, a pre-charging circuit pre-charges the smoothing capacitor from the input AC voltage. If a voltage having a magnitude larger than a prescribed value is applied to the DC power supply apparatus, an overvoltage protection circuit renders the rectifier circuit and the pre-charging circuit inoperative.

DC power supply apparatus

An AC voltage applied among power input supply terminals is rectified by a rectifier, and the rectified voltage is adapted to be reduced in a voltage-reducing converter with a switch connected in parallel with it. A switching circuit connect smoothing capacitors in series or parallel to the voltage-reducing converter. Inverters are connected in parallel with the respective smoothing capacitors. The output voltages of the inverters are voltage-transformed by transformers. The transformed voltages from the transformers are converted to DC voltages by converters. A control unit renders the voltage-reducing converter operative and causes the switching circuit to connect the smoothing capacitors in series when a third AC voltage is applied among the power supply input terminals. When a second AC voltage lower than the third AC voltage is applied among the power supply input terminals, the control unit causes the switch connected in parallel with the voltage-reducing converter to be closed and causes the switching circuit to connect the smoothing capacitors in series. If a first AC voltage about one-half as high as the second AC voltage is applied, the control unit causes the switch to be closed and causes the switching circuit to connect the smoothing capacitors in parallel.

DC power supply apparatus for arc-utilizing apparatuses

An input-side rectifier of a DC power supply apparatus receives and rectifies an AC voltage selected from first and second groups of AC voltages. The AC voltages in the second group are lower than those of the first group. A voltage boosting/lowering converter boosts or lowers the output voltage of the input-side rectifier to a voltage having a predetermined value. An inverter converts the output voltage of the voltage boosting/lowering converter to a high-frequency voltage. A voltage transformer transforms the high-frequency voltage from the inverter. An output-side rectifier rectifies the transformed high-frequency voltage from the transformer.

DC power supply apparatus including boosting/lowering converter unit and

An inverter includes a series circuit of two current conducting units connected between two input terminals adapted to be connected to a DC power supply. Two first capacitors are connected in series between the two input terminals. A primary winding of a transformer is connected between the junction of the current conducting units and the junction of the first capacitors. Each of the current conducting units includes a parallel circuit of an IGBT, a diode and a second capacitor. The IGBT has a collector, an emitter and a gate and is rendered conductive when a control signal is applied to the gate while a voltage of a predetermined polarity is applied between the collector and the emitter. The diode is connected in inverse parallel with the IGBT. An inverter control circuit applies alternately the control signals to the respective IGBTs with a predetermined quiescent period disposed between the respective control signals applied.

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Kawanishi, Japan

Toshikazu Fujiyoshi