Daikin Industries, Ltd.

Takurou Ogawa

Morimitsu Sekimoto

Nobuo Hayashi

Tomoisa Taniguchi

Eiji Tooyama

Daisuke Ueki

Hiroshi Hibino

Takayuki Miyajima

Masanobu Tomoe

Akiko Sera

An air conditioner includes an indoor unit, outdoor unit, indoor unit power line, and outdoor unit power line. The power lines branch from a common power line. Each of the indoor and outdoor units includes a converter circuit, an inverter circuit, and a capacitor. A total of effective values of integer-order components from second to 40th orders in a total current, which is obtained by adding up an indoor-unit input current and an outdoor-unit input current and which flows through the common power line, is less than a sum of a total of effective values of integer-order components from the second to 40th orders included in the indoor-unit input current that flows through the indoor-unit power line and a total of effective values of integer-order components from the second to 40th orders included in the outdoor-unit input current that flows through the outdoor-unit power line.

Air conditioner

A direct power conversion device includes a control unit. tb=1/|fdc&#x2212;n&#xd7;fL|. fdc is a frequency twice as high as a frequency of an AC power supply, fL is a frequency of periodic load fluctuations, and n is a positive integer that maximizes tb. In a half period of power supply during a period of tb, the half period including a timing at which peaks of a fundamental wave of load torque and an absolute value of a power supply voltage substantially coincide with each other, the control unit being configured to control the switching elements so that two or more local maximum points appear in the half period of power supply, in a waveform obtained by combining a second harmonic, a fourth harmonic, and a sixth harmonic of a power supply frequency contained in a waveform of an absolute value of a motor current vector.

Direct power conversion device

In order to suppress vibration with a motor a load torque of which periodically fluctuates, an output torque of the motor is controlled to be periodically changed. In this case, in order to increase a vibration suppressing component by a direct power conversion apparatus, at least one of first control and second control is performed. In the first control, an output torque having a waveform including a fundamental frequency component of the load torque a fundamental frequency of which is a frequency in accordance with a fluctuation period of the load torque and at least one of a fourth harmonic and a sixth harmonic of a power source frequency of an AC power source is generated. In the second control, the output torque having a waveform including at least one of a second harmonic and a third harmonic of the fundamental frequency of the load torque and a second harmonic of the power source frequency of the AC power source is generated.

Power conversion apparatus

A power converter includes a plurality of switching elements, a converter circuit that rectifies an AC voltage of an AC power source, a DC link that receives output of the converter circuit and generates a DC voltage, an inverter circuit that converts the DC voltage into an AC voltage of a predetermined frequency through a switching operation, and a control unit that controls the switching operation. A capacitance value of a capacitor is set so that a maximum value of the DC voltage becomes twice or more of a minimum value. The control unit controls the switching elements such that two or more extrema appear in a power source half cycle in a waveform synthesized from second, fourth, and sixth harmonics that have a power source frequency as a fundamental frequency and are extracted from a waveform of an absolute value of a motor current vector.

Power conversion device

The voltage detection circuit () is a voltage divider circuit including a plurality of resistances (toandto) and detects voltages (Vac, Vac) correlating with a power source voltage (Vin) of the AC power source (). The calculation unit () obtains the across voltage (VL) of the reactor () using detection results (Vac, Vac) of the voltage detection circuit (), and estimates a power source current (Iin) based on the across voltage (VL). The calculation unit () corrects gains of the detection results (Vac, Vac) so that a value correlating with an average value per predetermined time period of the estimated power source current (Iin) matches a value correlating with an average value per the predetermined time period of a current (Iinv) downstream of the capacitor (), and obtains the across voltage (VL) using the detection results (Vac, Vac).

Current estimating device

Disclosed herein is a power conversion device including a storage and a power conversion controller. The storage stores multiple values, each correlated to a disturbance that causes distortion in a current to a power converter, in association with a phase angle of a voltage of an AC power supply. The power conversion controller controls ON/OFF operations by using the values stored in the storage to compensate for a manipulated variable of control performed by the power converter in association with the phase angle of the voltage of the AC power supply.

Power conversion device with reduced current deviation

A DC voltage value from a DC voltage detection section is input directly to a voltage correction section without passing through a compensator or a filter. Therefore, even when rapid voltage change occurs, such as short power interruptions, instantaneous voltage drop and return from instantaneous voltage drop, the voltage correction section can quickly perform the correction operation in response to the rapid voltage change. Since the amount of link resonance compensation is limited by the limitation section to a certain range, it is possible to prevent the amount of link resonance compensation from fluctuating excessively upon rapid voltage change. Since the amount of link resonance compensation which is limited by the limitation section to a certain range is input to one compensator that has an appropriate control band, among all control calculation sections, the response does not have to be unnecessarily fast, thus realizing a stable control.

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Osaka, Japan

Takurou Ogawa