Daikin Industries, Ltd.

Morimitsu Sekimoto

Toshiyuki Maeda

Takurou Ogawa

Hiroshi Hibino

Tomoisa Taniguchi

Nobuo Hayashi

Reiji Kawashima

Hiroyuki Yamai

Eiji Tooyama

Kenichi Sakakibara

Abdallah Mechi

Hitoshi Haga

Daisuke Ueki

Kazushi Hisayama

Sumikazu Matsuno

Yasutaka Taguchi

Akiko Sera

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

An inverter circuit () is configured so as to perform synchronous rectification by six switching elements (). The switching element () is formed of an unipolar device (SiC MOSFET in this case) using a wideband gap semiconductor. The inverter circuit () uses the body diode () of SiC MOSFET () as a freewheeling diode during synchronous rectification.

Power converter having switching elements formed of unipolar devices using a wideband gap semiconductor

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

An electric power conversion device includes: a converter circuit which includes a boost chopper; a capacitor which is connected between output terminals of the converter circuit; a boost chopper which boosts a terminal voltage of the capacitor; a multiphase inverter circuit; and a boost chopper controller. In a case where the operation of the boost chopper is continuously stopped, the capacitor has a capacitance allowing the terminal voltage of the capacitor to have a pulse frequency twice as high as that of the AC power source. The multiphase inverter circuit has an output power which is allowed to fluctuate in synchronization with a power source.

Electric power conversion 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 power conversion apparatus is equipped with switching devices to perform power conversion of input AC power supplied from an AC power supply to output AC power having a predetermined voltage and a predetermined frequency, and to supply the power to a motor connected thereto. The apparatus includes a controller controlling switching of the switching devices, a capacitor smoothing a ripple generated by the switching of the switching devices, a current controller controlling a current flowing to the motor, and a voltage distortion corrector detecting a harmonic component caused by distortion in motor input power, and superimposing compensation values on an output of the current controller in accordance with a value of the harmonic component.

A DC link is provided, which includes a capacitor connected in parallel to an output of a converter circuit, and outputs a pulsating DC link voltage. An inverter circuit is provided, which converts an output of the DC link to AC by switching, and supplies the AC to a motor connected thereto. A controller is provided, which controls switching of the inverter circuit so that motor currents pulsate in synchronization with pulsation of a power-supply voltage. The controller controls the switching of the inverter circuit in accordance with a load of the motor or an operational state of the motor, and reduces pulsation amplitude of the motor currents.

A bidirectional switch circuit includes two switching elements connected to conduct a current in both directions. The two switching elements are connected in series to each other. Of the two switching elements, the switching element to which a reverse voltage is applied, a voltage of a source of one of the switching elements being higher than a voltage of a drain of the one, is configured to conduct a current from the source to the drain even when an on-drive signal is not being input to a gate terminal of the one.

Bidirectional switch circuit configured to conduct current in reverse direction without applying an on-drive signal and power converter including the same

A power converter circuit includes a diode group, a relay, a DC section and an inverter. The diode group includes a plurality of diodes arranged to rectify an output voltage of an alternating-current power supply. The relay is provided at a point located closer to the alternating-current power supply than the diode group. The DC section is where an output voltage of the diode group is applied. The inverter is arranged to output a three-phase alternating-electric current to a three-phase load. The DC section has a maximum pulse voltage twice as great as a minimum pulse voltage of the DC section. The DC section includes an energy-absorbing circuit having an electrolytic capacitor. The DC section further has a pathway arranged to apply the output voltage of the alternating-current power supply from the alternating-current power supply to the electrolytic capacitor via a rectifying circuit, not via the relay.

Power converter circuit

A power converter includes a power converter section () (e.g., an inverter circuit) having a plurality of switching elements (S, S) in which a current can flow in a reverse direction, and a control section () which determines on-state time of each of the switching elements (S, S) according to an output voltage of the power converter section (), thereby switching on/off states of the switching elements (S, S). The control section () instructs the power converter section () to perform synchronous rectification, and corrects the on-state time according to a drop of an on-state voltage of each of the switching elements (S, S).

Power converter

A multiphase current supplying circuit according to the present invention includes a diode bridge, an intervening circuit, an inverter, a control circuit, and a lightning arrester. The diode bridge is connected to a single-phase AC power supply system via the lightning arrester, and performs full-wave rectification on a single-phase AC voltage. The intervening circuit includes a capacitor and an inductor, and is constituted by a choke input type low-pass filter. More specifically, one end of the inductor and one end of the capacitor are connected, output from the diode bridge is received between the other end of the inductor and the other end of the capacitor, and a rectified voltage generated at both ends of the capacitor is output to the inverter.

Multiphase current supplying circuit, driving apparatus, compressor, and air conditioner

A motor control unit () includes: a power converter () having a rectifier circuit () which rectifies an AC voltage from an AC power supply (), a capacitor circuit () which receives an output of the rectifier circuit () and outputs a rectified voltage having pulses from both ends of a capacitor () and an inverter circuit () which receives the rectified voltage and outputs an AC voltage to the motor (); and a motor controller () controlling the motor () by controlling the inverter circuit (). The motor controller () performs torque control to vary an output toque of the motor () in response to variation in load torque of the motor ().

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Shiga, Japan

Morimitsu Sekimoto