Daikin Industries, Ltd.

Masaki Kono

Reiji Kawashima

Takayuki Fujita

Tomoisa Taniguchi

Masahide Fujiwara

Keisuke Ohta

Ryou Matsuyama

Hirotaka Doi

Hirotaka Saruwatari

Yoshitsugu Koyama

Kazuya Tsubouchi

Jun Takahashi

Koudai Okuzono

Yuu Yoshikawa

Kodai Okuzono

A noise reduction circuit includes: noise canceler circuitry configured to inject a compensation current into a power line and ground to reduce a common mode noise current that flows through the power line and the ground into a commercial power supply from a power converter with a switching element connected to the commercial power supply; and overcurrent inhibitor circuitry provided on a compensation current path through which the compensation current flows, the overcurrent inhibitor circuitry being configured to inhibit application of an overcurrent to the noise canceler circuitry.

Noise reduction circuit, power conversion device, and refrigeration apparatus

A power conversion system includes an inverter circuit, a harmonic reducer, and a synchronizer. The inverter circuit is operable with electric power supplied from an alternating-current power source. The harmonic reducer is connected to the alternating-current power source. The inverter circuit includes a circuit main portion and a conversion control unit configured to control the circuit main portion. The harmonic reducer includes a current control unit configured to perform control to reduce a harmonic current flowing to the alternating-current power source. The synchronizer is configured to synchronize a state of the harmonic reducer with a state of the inverter circuit.

Power conversion system

A converter circuit converts AC electric power into DC power. An inverter circuit converts the DC power into AC power. A capacitor is connected in parallel to each of the converter circuit and the inverter circuit between these circuits. The capacitor allows variation of an output voltage from the converter circuit, and absorbs variation of an output voltage from the inverter circuit due to a switching operation. An overvoltage protection circuit includes a resistor and a semiconductor element connected in series to each other. The overvoltage protection circuit is connected in parallel to the capacitor to protect the inverter circuit from an overvoltage. First and second control units respectively control the inverter circuit and the overvoltage protection circuit.

Power conversion device

An air conditioner is connected to an AC power source. The air conditioner includes an adjustment unit and a control unit. The adjustment unit adjusts apparent power at a power source input terminal of the air conditioner. The control unit controls the adjustment unit, based on information according to a target value of apparent power to be supplied to the AC power source from the air conditioner.

Air conditioner

A power converter includes a power conversion unit for a three-phase alternating current output from an alternating-current power source, and a current compensation unit that supplies a compensating current to the alternating-current power source. The current compensation unit includes a current compensation unit inverter including switching elements, a current compensation unit capacitor, a current compensation unit reactor, a compensation controller that obtains an output voltage command value, and a drive signal generator that generates a drive signal usable to drive the switching elements by a three-phase modulation method. The current compensation unit inverter supplies the compensating current to the alternating-current power source via the current compensation unit reactor. Td≤(34.00/fsw−0.145)(1.55−0.055*Pmax), where fsw represents a carrier frequency employed for generation of the drive signal, Pmax represents a maximum input power of the power conversion unit, and Td represents a dead time for the drive signal.

Power converter and heat pump system provided therewith

A power conversion device () is supplied with an electric power from an alternating current power source (). An active filter device (), which is a power source quality improvement unit, improves a quality of the alternating current power source (). A controller () limits an operation of the power conversion device () so that any one of a power-source electric power, a power-source current, and a power-source harmonic obtained when a failure detection unit () detects a failure of the active filter device () becomes less than or equal to a maximum value of a corresponding one of the power-source electric power, the power-source current, and the power-source harmonic, the maximum value being obtained when no failure has occurred in the active filter device ().

Power source quality management system and air conditioning apparatus

A plurality of active filter devices () that each have an output connected to a harmonic-generating load device () and are capable of generating a compensating current for performing at least one of reduction of a harmonic current of the harmonic-generating load device () and improvement of the power factor of the fundamental wave are provided. The plurality of active filter devices () provide two or more types of capacities, and the number and combination of operating active filter devices among the active filter devices () change in accordance with the magnitude of the compensating current.

Active filter system and air conditioning device

A gate voltage control/gate resistance changing circuit () is accommodated in the same package (P) as a switching element (), and outputs a driving signal to the switching element () to control turning on and off of the switching element (). When an external signal is input from outside of the package (P) to a terminal () of the package (P), a changing unit () accommodated in the package (P) changes the switching speed of the switching element () based on the signal.

Semiconductor device

A controller performs a first control for controlling the power source power factor or a power source harmonic of the harmonic current such that an input power factor of at least one of a plurality of connection devices changes in a direction preceding the power source power factor in a case where the power source power factor changes in a lagging direction, and performs a second control for controlling the power source power factor or the power source harmonic such that the input power factor of at least one of the connection devices changes in a direction lagging behind the power source power factor in a case where the power source power factor changes in a leading direction.

Power source quality management system and air conditioner

A load apparatus is connected to an AC power source and is supplied with power from the AC power source. An operation state control unit controls, based on a target value about a power-source quality including either a power-source power factor of the AC power source or a power-source harmonic of the AC power source and on a present power-source quality, an operation state of the load apparatus.

Power-source power factor control system, phase modifying apparatus, and active filter apparatus

In a device with a built-in active filter, the device incorporating an active filter therein and being connected to an AC power source, the active filter operates based on a value detected by a load information detection unit detecting load information on an AC power source outside the device with a built-in active filter.

Growing community of inventors

Osaka, Japan

Masaki Kono