Omron Corporation

Satoshi Iwai

Wataru Okada

Noriyuki Nosaka

Takeo Nishikawa

Hironori Nakada

Takanori Ishii

Gun Eto

Mamoru Sueki

Kenji Kobayashi

Takayoshi Tawaragi

Yuhki Kamatani

Hironori Tauchi

Takuro Hashimoto

Hiroki Kawano

Kuniyuki Hirai

Keiji Shiraishi

The overcurrent protection circuit includes: a first transistor having an emitter connected to a control voltage; and a second transistor having a base connected to a collector of the first transistor, a collector connected to a base of the first transistor and pulled up to a voltage, and a grounded emitter. When the control voltage exceeds a first threshold voltage, the first and second transistors are turned on, the control voltage decreases as a result of decrease in the pull-up voltage, and a protection operation to turn a switching element off is started, and the overcurrent protection circuit includes a first diode connected between the control voltage and the emitter of the first transistor, and an element circuit connected between the emitter and the base thereof. The element circuit includes any of a second diode, a first resistor, and a parallel circuit including the second diode and the first resistor.

Overcurrent protection circuit for protecting semiconductor device from overcurrent at high speed, and switching circuit provided with the overcurrent protection circuit

A driving circuit that drives a switching element, the driving circuit includes: a controller that includes a first terminal connected to a gate terminal of the switching element and a second terminal connected to a source terminal of the switching element, and outputs a control signal from the first terminal to the gate terminal; a first capacitor and a first resistor connected in parallel; and a second capacitor and a second resistor connected in parallel, in which the first capacitor and the first resistor are connected in series to a first connecting wire for connecting the gate terminal and the first terminal on the gate terminal side of the first connecting wire, and in which the second capacitor and the second resistor are connected in series to the first connecting wire on the first terminal side of the first connecting wire.

Driving circuit for switching element and switching circuit

An overcurrent protection circuit is provided for protecting an overcurrent flowing through a switching element that is controlled to be turned on and off based on a drive signal. The overcurrent protection circuit includes: a first transistor that is an N-channel field effect transistor (FET) having a drain connected to a control terminal of the switching element and a grounded source; a second transistor that is a PNP bipolar transistor having an emitter connected to the control terminal of the switching element, a collector connected to a gate of the first transistor and grounded via a first capacitor, and a base pulled up to a predetermined pull-up voltage; and a ground circuit connected in parallel with the first capacitor.

Overcurrent protection circuit for protecting overcurrent flowing through switching element and switching circuit with the overcurent protection circuit

A driving circuit for a switching element that drives a switching element of a current-driven type. The driving circuit includes a controller including a first terminal and a second terminal and that outputs a control signal to a gate terminal of the switching element. A first resistor, which regulates a current serving as the control signal, is connected to the first terminal, and a first capacitor is connected in parallel to the first resistor. A second resistor and a second capacitor are connected in parallel, and a current path extends from the first resistor and the first capacitor to the gate terminal and from a source terminal of the switching element to the second terminal of the controller. The second resistor and the second capacitor are in the current path.

A power converter apparatus includes a switching circuit generating an AC voltage by switching a DC voltage at a predetermined switching frequency, and a filter circuit converting the AC voltage from the switching circuit into the DC voltage by low-pass filtering the AC voltage. The filter circuit includes first and second bypass capacitors, and an inductor. The first bypass capacitor bypasses noise of a first frequency component of the AC voltage from the switching circuit, and the second bypass capacitor bypasses noise of a second frequency component of the AC voltage from the switching circuit, which is lower than the first frequency component. The inductor is between the first and second bypass capacitors, and the inductance thereof is set so that a resonance frequency of the filter circuit is lower than multiple times the switching frequency by insertion of the inductor, thereby reducing the switching noise flowing to the load.

Power converter apparatus provided with low-pass filter circuit for reducing switching frequency components

An overcurrent protection circuit is provided for a switching element turned on/off based on a control voltage. The overcurrent protection circuit includes a first transistor and a second transistor. The first transistor is a PNP bipolar transistor and has an emitter connected to the control voltage. The second transistor is an NPN bipolar transistor and has a base connected to a collector of the first transistor, a collector connected to a base of the first transistor and pulled up to a predetermined pull-up voltage, and a grounded emitter. When the control voltage exceeds a predetermined first threshold voltage, the first and second transistors are turned on, the control voltage is dropped by drop of the pull-up voltage, and thus the overcurrent protection circuit starts a protection operation of turning off the switching element.

Overcurrent protection circuit for switching element turned on and off based on control voltage

A driver circuit controls a first switch element. A first resistor is connected between the driver circuit and the first switch element. A second switch element is connected to the first switch element. An overcurrent detector circuit controls the second switch element based on an overcurrent current flowing through the first switch element. A second resistor is connected between the overcurrent detector circuit and the second switch element. The first and second resistor is set such that a turn-off time of the first switch element when the second switch element is turned on by the overcurrent detector circuit is longer than a turn-off time of the first switch element when the first switch element is turned off by the driver circuit.

Switch circuit capable of overcurrent protection with small and simple circuit, and with simple operation, without affecting normal operation

A power converter apparatus is provided to include a switching circuit, and a filter circuit. The switching circuit generates an AC voltage by switching a DC voltage at a predetermining switching frequency, and the filter circuit converts the AC voltage from the switching circuit into the DC voltage by low-pass filtering the AC voltage. The filter circuit induces first and second bypass capacitors, and an inductor. The first bypass capacitor bypasses noise of a first frequency component of the AC voltage from the switching circuit, and the second bypass capacitor bypasses noise of a second frequency component of the AC voltage from the switching circuit, which is lower than the first frequency component. The inductor is inserted between the first and second bypass capacitors, and the inductance thereof is set so that a resonance frequency of the filter circuit is lower than the switching frequency by insertion of the inductor.

A switching elementhas a gate terminal connected to an output end Vout of a driving circuitvia a capacitorand a resistorconnected in parallel. The switching elementhas a source terminal connected to the driving circuitvia a capacitorand a Zener diodeconnected in parallel. The Zener diodehas an anode terminal connected to the source terminal of the switching elementand a cathode terminal connected to the driving circuit

Driving circuit for switching element, and switching circuit

A switching elementhas a gate terminal connected to an output endof a driving circuitvia a capacitorand a resistorconnected in parallel. The switching elementhas a source terminal connected to the driving circuitvia a capacitor. A diodeconnected in series with a resistorhas a cathode terminal connected to a section between the capacitorand the resistor, and the gate terminal and an anode terminal connected, via the resistor, to a section between the source terminal and the capacitor

An inverter has a plurality of switching elements, the states of which are each switched by a pulse signal supplied in accordance with a power grid voltage. The inverter is provided with: a switching circuit that converts an input DC voltage to an AC voltage and outputs the AC voltage to a pair of output lines; a filter circuit having output coils inserted in the output lines; a current detection sensor that detects the current flowing through the output coils; and a high-speed pulse control circuit that, when an absolute value of the detected current is a threshold value or more, stops the supply of the pulse signal to the switching circuit.

Inverter device capable of suppressing overcurrent without increasing a load and operation control method

An inverter circuit provided in a power conversion device includes a full-bridge inverter, and a short circuit part. The short circuit part includes switching elements and clamp elements connected to the switching elements. The clamp elements suppress application of an excessive voltage such as a surge voltage to the switching elements.

Growing community of inventors

Hirakata, Japan

Satoshi Iwai