Hitachi, Ltd.

Hitachi Appliances, Inc

Junpei Uruno

Hiroyuki Shoji

Mutsuhiro Mori

Akihiko Kanouda

Yasuo Kaminaga

Yasuhiko Kohno

Takae Shimada

Toshikazu Okubo

Yasuhiko Kouno

Masayuki Isogai

A power converting apparatus having a gate drive circuit including a push-pull circuit consisting of two transistors at its output stage; a diode connected in series with the push-pull circuit; a gate power source connected in parallel with the series circuit of the push-pull circuit and the diode; a negative voltage generating circuit connected in parallel with the push-pull circuit; a transistor connected between the output terminal of the negative voltage generating circuit and the negative terminal of the gate power source, wherein the output voltage of the push-pull circuit is switched from positive polarity to negative polarity and vice versa depending on the signal applied to the base terminals of the transistors.

Gate drive circuit of the voltage drive type semiconductor element and power converter

A unidirectional DC-DC converter and method of control thereof. The converter includes a DC power-supply, a buck converter circuit having a first main switching element, a boost converter circuit having a second main switching element, a first snubber capacitor, a first inversely-parallel diode, a control device, and an output diode.

Buck-boost DC-DC converter with auxiliary inductors for zero current switching

A small and efficient DC-DC converter is provided. In this DC-DC converter, passive elements such as an inductor and a capacitor can be reduced in size by reducing switching loss by a soft switching technology and increasing the drive frequency of a switching element. The DC-DC converter has a main switching element, a main diode and an auxiliary circuit that discharges the electric charges of the capacitance between the ends of the main switching element. The DC-DC converter includes an auxiliary inductor magnetically coupled with the main inductor, an auxiliary switching element that stores energy in the auxiliary inductor, and an auxiliary diode that discharges energy stored in the auxiliary inductor to the direct-current power source or the output side. The auxiliary inductor is coupled with the main inductor in the direction in which backward voltage is applied to the auxiliary diode when the main inductor discharges energy.

DC-DC converter

A unidirectional DC-DC converter which has a simple control circuit without using multiple insulated power supplies or a transformer, uses an auxiliary inductor of a comparatively small capacitance, reduces the size and weight of the converter, and has a very great capacitance without switching of supply current. For example, a unidirectional DC-DC converter equipped with main IGBTwhich supplies and shuts off current for first inductorand diodewhich discharges energy from main inductorto an the output. The DC-DC converter is further equipped with auxiliary IGBTwhich applies current to back-to-back-connected diodeby using energy stored in auxiliary inductorwhich is magnetically coupled with main inductor. This applies current to the back-to-back-connected diode in a short period including a time period in which the first switching element is turned on and accomplishes ZVZCS.

Unidirectional DC-DC converter

A soft switching DC-DC converter is provided which includes circuitry for both a buck converter and a boost converter. The buck converter circuitry and the boost converter circuitry share a common transformer including a primary coil and first and second secondary coils. A first switching element is coupled to a first capacitor to provide the buck converter operation while another switching element is provided to provide the boost converting operation. The primary coil of the transformer is commonly used as a choke coil by both the buck converter and the boost converter. In this way, size and cost reduction can be obtained.

Soft switching DC-DC converter including a buck converter and a boost converter sharing a common transformer

An igniter of the present invention has an insulated gate semiconductor device having a collector terminal, an emitter terminal and a gate terminal, a current control circuit which limits current by controlling voltage at the gate terminal when current for flowing through the insulated gate semiconductor device exceeds a fixed value, a voltage monitor circuit for detecting a potential of the collector, and a control current adjusting circuit for controlling current which flows through the gate terminal by receiving output from the voltage monitor circuit.

Car-mounted igniter using IGBT

A circuit for supplying an oscillation suppress current is provided between a collector terminal and gate electrode of a main IGBT. The current supply circuit comprises a resistor and a diode which are connected in series. A bypass MOSFET is connected between the series connection and the emitter terminal. No semiconductor element having different temperature characteristics is provided in the current supply circuit.

Vehicle-mounted ignitor

A circuit incorporated IGBT is provided with a semiconductor substrate having an IGBT area and a circuit area which are adjacent to each other. In a semiconductor layer of one conductivity type in which a circuit element is formed in the circuit area, there is provided another semiconductor layer of another conductivity type which adjoins the circuit element and has an impurity concentration higher than that of the semiconductor layer of the one conductivity type. An electrode contacts the other semiconductor layer and is connected to an electrode of the IGBT. Carriers are ejected from the other semiconductor layer to the electrode of the IGBT, thereby making it possible to prevent an erroneous operation of the circuit.

Growing community of inventors

Tokai, Japan

Junpei Uruno