Mitsubishi Electric Corporation

Actis Corporation

Takuya Sakai

Satoshi Azuma

Kenichi Morokuma

Hiroyasu Iwabuki

Hiroshi Nakatake

Kosuke Nakano

Kohei Onda

Noriyuki Haneda

Yoshiaki Higashino

Toshihiro Sano

A drive adjustment circuit for a power semiconductor element includes a differentiating circuit to differentiate a gate voltage of a power semiconductor element, a power supply to generate a comparison reference voltage, a comparator having a first input terminal connected to the differentiating circuit and a second input terminal receiving the comparison reference voltage, and a voltage adjusting circuit to adjust a gate voltage of the power semiconductor element based on an output of the comparator.

Drive adjustment circuit for power semiconductor element, power module, and power conversion device

A detection circuit is provided to output a feedback signal and a adjustment current when a voltage of a high-voltage side main terminal of a semiconductor switching device is equal to or higher than a preset threshold value in a period in which a gate drive circuit turns off the semiconductor switching device to cut off a current, a control circuit diagnoses a state of the semiconductor switching device or controls a signal to be outputted to the gate drive circuit, on the basis of the feedback signal, and a gate current, which is an output of the gate drive circuit, is adjusted by the adjustment current.

Drive circuit for semiconductor switching device

Provided is a power semiconductor element gate driving circuit that performs ON/OFF control on main current of a power semiconductor element having a gate electrode by charging the gate electrode of the power semiconductor element with electric charges and discharging the electric charges on the basis of an inputted gate signal. When the gate signal is switched to an OFF signal, control is performed such that gate current for discharging the electric charges from the gate electrode increases in association with increase in a temperature of the power semiconductor element and decreases in association with increase in the main current.

Gate driving circuit for power semiconductor element

A drive circuit of a power semiconductor element comprises a gate drive voltage generator to generate, based on an ON/OFF drive timing signal input to an input terminal, a gate drive voltage to be applied to a gate electrode of a switching element having the gate electrode for controlling a main current that flows between a first main electrode and a second main electrode, wherein the gate drive voltage generator includes a gate current limiting circuit in which a current limiter to limit a current and a voltage limiter to limit the magnitude of a voltage applied to both ends of the current limiter are connected in parallel.

Drive circuit of power semiconductor element

A power semiconductor device protection circuit includes: a drive circuit that drives a power semiconductor device; a current detector which includes a first resistor and an inductor connected in parallel; and a detection circuit that detects a short-circuit condition of the power semiconductor device. One end of the first resistor and one end of the inductor are connected to one terminal of the power semiconductor device. The detection circuit detects the short-circuit condition of the power semiconductor device by comparing a voltage of the one terminal of the power semiconductor device, which changes as a function of current flow through the first resistor and the inductor, with a short-circuit detection voltage. A reference potential of the drive circuit is connected to the other end of the first resistor and the other end of the inductor.

Power semiconductor device protection circuit and power module

During regenerative control of an inverter circuit, when a path between a DC power supply and a smoothing capacitor is in a disconnection state, a control circuit of a power conversion device performs control while switching between first control in which upper switching elements within the inverter circuit are turned on and all lower switching elements are turned off and second control in which the lower switching elements are turned on and all the upper switching elements are turned off, every predetermined switching period.

Power converter for controlling switching elements during regenerative control of an inverter

A temperature detection circuit for detecting a temperature of a switching element, a current source for causing a forward current to flow to the temperature detection circuit, an amplifier circuit for amplifying a forward voltage of the temperature detection circuit, a current adjustment circuit for adjusting a magnitude of a gate current to the switching element on the basis of an output voltage of the amplifier circuit, and a drive circuit for receiving an external signal and turning ON/OFF the switching element, are included. The magnitude of the gate current caused to flow from the current adjustment circuit to the gate electrode of the switching element is adjusted on the basis of a change in a magnitude of the forward voltage corresponding to a change in the temperature of the temperature detection circuit.

Gate driving circuit including a temperature detection circuit for reducing switching loss and switching noise

A communication speed control system to be placed between service providing servers on the Internet and smartphones, the communication speed control system including: a traffic storing unit a non-regulated IP address storing unit for registering IP addresses of the servers a packet reading unit for extracting an IP address of the server from the packet; a traffic management unit for calculating cumulative data traffic of the IP address in question a handling rule management unit for determining that a band limitation is required when the cumulative data traffic exceeds a threshold value and the IP address in question is not registered as a non-regulated IP address, and determining that a band limitation is not required when the cumulative data traffic does not exceed the threshold value and a packet transmission unit for transmitting a packet at a normal communication speed.

Communication speed control system

In a system supplying power from an AC power supply to a three-phase motor via a converter and an inverter, a leakage current reducing apparatus is connected to a connection line between the AC power supply and the converter. A common mode transformer detects, as common mode voltage, common mode current flowing from the AC power supply to the connection line. The common mode voltage is inputted to a voltage amplifier via a filter apparatus. Output voltage obtained by voltage amplification passes through a capacitor and then is applied as an AC component to a neutral point of capacitors connected in a Y-connection fashion, so as to have the same phase as that of the common mode voltage. Thus, current having the same phase as that of the common mode current is supplied via the capacitors to the converter through the connection line, thereby reducing the common mode current.

Leakage current reducing apparatus

Three-phase windings-and-of a first common-mode transformerand a second common-mode transformerare connected in series through connecting lines-, respectively. The windings-are connected to an unillustrated AC power supply by connecting lines-. The windings-are connected to a three-phase motor by connecting lines-and through a converter and an inverter which are unillustrated. A windingfor common-mode voltage detection detects high-frequency leakage currents flowing through the connecting lines-as a common-mode voltage V, and an output voltage Vobtained by voltage amplification by a voltage amplifieris applied to a windingfor common-mode voltage application in such a manner that the output voltage Vworks in generally the same direction as the common-mode voltage V, thereby canceling out the high-frequency leakage currents through the windings-. Since a voltage amplification method is used, it is possible to reduce the high-frequency leakage currents with a simpler configuration as compared to a conventional current amplification method.

Leakage current reduction apparatus that includes a voltage amplifier and a voltage applicator

First windings of a first common mode transformer and second windings of a second common mode transformer are connected in series via connection lines. The windings are connected to an AC power supply via connection lines. The first windings are connected to a three-phase motor via connection lines, a converter, and an inverter. High-frequency leakage currents flowing in the connection lines are detected as a common mode voltage by a winding for common mode voltage detection. An output voltage is inputted via a filter to a voltage amplifier unit that amplifies the output voltage, and the amplified voltage is applied to a winding via a capacitor in substantially a same direction as a direction of the common mode voltage. As a result, leakage currents are reduced by induced voltages on the windings.

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Tokyo, Japan

Takuya Sakai