Daikin Industries, Ltd.

Kenichi Sakakibara

Reiji Kawashima

Hitoshi Haga

Toshiyuki Maeda

Morimitsu Sekimoto

Takayuki Fujita

Abdallah Mechi

Sumio Kagimura

Tomoisa Taniguchi

Keisuke Ohta

Naoya Yamashita

Kuniomi Oguchi

Isao Tanatsugu

In a first section of a power conversion device, a second switch is turned off, a first duty drec and a third duty dz are selected so that a direct current voltage Vdc to be input to a current source becomes equal to a direct current voltage command value Vdc*, a first conversion operation of supplying power from the voltage source to the current source is performed, and the capacitor is charged by the rectified voltage via the clamp diode. In a second section of the power conversion device, a first switch is turned off, a second duty dc and the third duty dz are selected so that the direct current voltage Vdc to be input to the current source becomes equal to the direct current voltage command value Vdc*, and a second conversion operation of supplying power from the capacitor to the current source is performed.

Power conversion device performing first and second conversion operations

A power converter includes a converter circuit, an inverter circuit, a clamp circuit, a scrubber circuit, and an element including a resistive component. The converter circuit generates from an AC voltage source a DC voltage with AC components superimposed. The inverter circuit has an input connected with an output of the converter circuit. The inverter circuit is configured to convert the DC voltage into an AC voltage by switching, and output the AC voltage to an inductive load. The clamp circuit includes a first capacitor and a first diode connected in series. The clamp circuit is connected between a positive output and a negative output of the converter circuit. The snubber circuit includes a second capacitor and a second diode connected in series. The snubber circuit is connected between the positive output and the negative output of the converter circuit.

Power conversion device

A direct power converter includes a converter that rectifies a single-phase AC voltage, converts AC power into DC power, and outputs first instantaneous power; a power buffer circuit that receives and supplies power between the converter and a DC link and that performs buffering second instantaneous power; and an inverter that converts a DC voltage at the DC link into a second AC voltage and outputs the second AC voltage. A period for which a current that flows from the converter to the power buffer circuit continuously flows in a period shorter than a half-period of the AC voltage is longer when third power input to the inverter, fourth power output by the inverter, or an average value of the first instantaneous power decreases to a value which is less than a first threshold, from a value which is greater than or equal to a second threshold that is greater than or equal to the first threshold.

Direct power converter and control device to improve an input power factor

A duty calculating unit receives a phase, an amplitude, a command value of a voltage across a capacitor, and a command value of a DC voltage, and calculates an original discharge duty and an original rectification duty. A duty correcting unit corrects the original discharge duty and the original rectification duty to obtain a discharge duty and a rectification duty. The duty calculating unit and the duty correcting unit can collectively be regarded as a duty generating unit that generates the discharge duty and the rectification duty.

Control device for direct power converter for reduction of harmonic distortion

A normalized-link-current estimation unit adopts a first value calculated by using a virtual DC voltage command, a phase and an amplitude of a single-phase AC voltage, and a distribution factor, as an estimated value of a value obtained by normalizing a link current flowing from a DC link to an inverter. A calculation unit determines a second value calculated by using the virtual DC voltage command, a rectified voltage, and a both-end voltage. When a normalized current command is less than a product of the first value and the second value, a normalized charge command is set to 0 and a rectifying duty is determined by dividing the normalized current command by the first value.

Control device for direct power converter

In a first section including a point of time when sums of periods while upper arm-side switches in a pair of current paths of a voltage source inverter conduct in one cycle of a carrier are equal to each other at zero, a first voltage command group corresponds to switching signals in which a period while the upper arm-side switches in all of the current paths are nonconductive in this one cycle is adjacently sandwiched by a pair of periods while all of the upper arm-side switches in the pair of current paths are nonconductive and other upper-arm side switch conducts.

Inverter control device

In a first period having a first period length, first data and second data are alternately given to an inverter control unit. The first data has a first value indicating a length of time from the start point of time of the first period to a matching point of time as a point of time when a converter carrier takes a converter threshold value and an inverter threshold value corresponding to a second period having the first value as its length. The second data has a second value indicating a length of time from the matching point of time to the end point of time of the first period and an inverter threshold value corresponding to a second period having the second value as its length.

Power converter control device

A control device includes a charge controller. The charge controller includes an amplitude determining unit, a charge command generating unit, and a charging operation controller. The amplitude determining unit determines an amplitude of a current to be input to a converter by performing at least proportional-integral control on a deviation between a voltage across the buffer capacitor and an average voltage command value that is a command value of an average of the voltage across the buffer capacitor. The charge command generating unit determines a charge command by multiplying by the amplitude a function determined according to a discharge duty, a rectifying duty, and a distribution factor of power. The charging operation controller controls a charging operation of the buffer capacitor on the basis of the charge command.

Direct-power-converter control device

A discharge duty that is a duty at which a switch is conductive takes a value obtained by dividing a product of a crest value of a single-phase AC voltage and a square of a cosine value of a phase of the single-phase AC voltage by a both-end voltage across a capacitor. A sum of a product of a rectifying duty that is a duty at which a converter is conductive and a rectified voltage output from the converter and a product of the both-end voltage and the discharge duty varies in a period that is a half of the period of the single-phase AC voltage.

Power converter

A converter full-wave rectifies a single-phase voltage, and outputs the rectified voltage across DC power supply lines. An inverter receives the rectified voltage, and supplies a three-phase AC current to an inductive load. A power buffer circuit is connected between the DC power supply lines. The power buffer circuit includes a discharge circuit and a charge circuit. The discharge circuit includes a capacitor and a switch connected in series to each other. The discharge circuit is configured, for example, by a boost chopper, and includes a switch, a reactor, and a diode. The power buffer circuit provides and receives part of pulsations of a power input into the converter to and from the DC power supply lines.

Power converter with a power buffer circuit whose buffered power is smaller than an AC component of a pulsating power

A converter performs full-wave rectification on a single-phase voltage, thus outputting a rectified voltage across DC power supply lines. An inverter receives the rectified voltage and then supplies a three-phase AC current to an inductive load. Between the DC power supply lines is connected a charge and discharge circuit. The charge and discharge circuit includes a buffer circuit and a boost circuit. The buffer circuit includes a series connection between a capacitor and a switch. The boost circuit, which may be configured by a boost chopper, includes a switch, a reactor and a diode. The charge and discharge circuit provides and receives part of pulsations of the power input to the converter between the DC power supply lines.

Control method for direct power converter

A plurality of capacitors are interposed between ones of a plurality of input lines. The clamp capacitor is connected between two DC power supply lines. A current-source converter includes a plurality of switch devices, where x represents r, s and t. The switch device selects conduction/non-conduction through a first diode between corresponding one of the input lines and the first DC power supply line and conduction/non-conduction through a second diode between said corresponding one of input lines and the second DC power supply line based on external signals and brings corresponding one of the input lines with the first and second DC power supply lines in a state of not receiving the signals.

Power converter with clamp capacitor on DC power supply line

In a first period when a cosine value is positive that is a cosine value of a value twice a phase angle determined while an AC waveform output from a single-phase AC power source is regarded as a sine value of the phase angle, a discharge duty for making a first switch conducting is set to be higher than a first value determined by dividing the product of an amplitude of an AC voltage of the single-phase AC power source and the cosine value by the product of an across voltage of a capacitor and &#x221a;2. In addition to or alternatively to this, in a second period when the cosine value is negative, a rectifying duty for making a diode rectifier conducting is set to be higher than a second value that is the reciprocal of the product of the absolute value of the sine value and &#x221a;2.

Method of controlling direct power converter

A first capacitor is provided between a first power supply line and a second power supply line. A charge/discharge circuit includes a second capacitor provided between the first power supply line and the second power supply line and a first switch connected in series to the second capacitor on the side of the first power supply line. A booster circuit boosts the rectified voltage from a diode rectifier to charge the second capacitor. A current blocking part is provided on the first power supply line or the second power supply line between the first capacitor and the second capacitor and blocks flowing of the current from the second capacitor to the first capacitor.

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Kusatsu, Japan

Kenichi Sakakibara