Abstract: A rectifier, a booster circuit configured to boost an output voltage of the rectifier, a smoothing capacitor configured to smooth an output voltage of the booster circuit, and an inverter circuit configured to convert a DC voltage of the smoothing capacitor to an AC voltage and drive a motor forming a part of a device supplied with the voltage after the conversion, are included. In addition, a reactor, a first backflow prevention element, a second backflow prevention element, a first switching element, a second switching element, an intermediate capacitor, and a controller configured to control the first switching element and the second switching element, are included.

Abstract: A power conversion apparatus includes a rectifier, a converter including a reactor, a switching element, and a reverse current prevention element, a smoothing capacitor configured to smooth the output voltage, a current detector configured to detect a reactor current, a voltage detector configured to detect the output voltage, and a converter control unit configured to control operation of the switching element of the converter. The converter-control unit includes a switching command calculation unit configured to calculate a switching command value responsive to a ratio of the rectified voltage to the output voltage in accordance with the output voltage and the reactor current, a switching control unit configured to control operation of the switching element in accordance with the switching command value, and a supply abnormality determination unit configured to determine occurrence of a momentary power failure or voltage sag in accordance with the switching command value.

Abstract: A power conversion apparatus, including: an MLC circuit configured to boost an input voltage from a three-phase rectifier; a smoothing capacitor configured to smooth an output of the MLC circuit; an inverter control unit configured to generate a PWM signal; an inverter circuit configured to convert a DC voltage of the smoothing capacitor into an AC voltage based on an input of the PWM signal and to supply the AC voltage to a motor; a boost mode switching unit having at least three boost modes in which a boost level of the input voltage is selected and configured to switch among the at least three boost modes depending on an operation status of the motor determined for the purpose of controlling a refrigeration cycle; and an MLC control unit configured to control the MLC circuit based on the switching by the boost mode switching unit.

Abstract: An adder adds a phase ?plus, which is n times a size of 60 degrees, to a phase output from a phase switching unit and outputs the phase as a voltage command phase ?. A voltage generation unit generates voltage command value based on the voltage command phase output by the adder and outputs the command value. A drive-signal generation unit, based on an output from the voltage generation unit generates drive signals corresponding to respective switching elements of an inverter, and outputs respective generated drive signals to the corresponding switching elements of the inverter, and generates a high-frequency AC voltage in the inverter.

Abstract: A voltage-command correction-value computation unit outputs a correction value for correcting a voltage command value according to a bus voltage. A multiplier calculates a voltage command value acquired by correcting the voltage command value based on the correction value. A voltage-command generation unit generates and outputs three-phase voltage command values based on the corrected voltage command value calculated by the multiplier and a phase. A PWM-signal generation unit generates six drive signals corresponding to switching elements of an inverter based on the three-phase voltage command values outputted by the voltage-command generation unit and a carrier signal. The PWM-signal generation unit outputs the generated drive signals to the corresponding switching elements of the three-phase inverter, to cause the inerter to generate a high-frequency AC voltage.

Abstract: A backflow preventing device includes a backflow preventing element that is connected between a power supply and a load and that prevents electric current from flowing backward from the load side toward the power supply side, a commutating device that performs a commutation operation for causing the electric current to flow to a commutation path connected in parallel with the backflow preventing element, and a controller that sets a time for performing the commutation operation and causes the commutating device to perform the commutation operation based on the set time. The backflow preventing device has a plurality of the commutation paths and has, for example, elements with small current-carrying capacities disposed in the commutation paths to achieve cost reduction and to cope with, for example, failures, thereby allowing for enhanced reliability for reducing recovery electric current.

Abstract: A voltage/current verifier computes, for each phase, a phase difference between phase voltage and phase current from the phase of phase voltage and the phase of phase current computed for each phase by a phase acquirer, and determines conformity if all of the computed phase differences are within a preset range. A current/current verifier computes phase differences between phase currents from the phase of phase current computed for each phase by the phase acquirer, and determines conformity if all of the computed phase differences are less than 180°. A reporting device reports that a current transformer is incorrectly placed on a power line unless both the voltage/current verifier and the current/current verifier do not determine conformity.

Abstract: A selection unit switches between a phase ?p and a phase ?n different from the phase ?p substantially by 180 degrees, and outputs one of them in synchronization with a carrier signal. A voltage-command generation unit generates and outputs three-phase voltage command values Vu*, Vv* and Vw* based on the phase outputted by the selection unit. A PWM-signal generation unit generates three-phase voltage command values Vu*?, Vv*? and Vw*? by correcting the three-phase voltage command values Vu*, Vv* and Vw* outputted by the voltage-command generation unit according to a predetermined method, and generates six drive signals corresponding to switching elements of the inverter based on the three-phase voltage command values Vu*?, Vv*? and Vw*? and the carrier signal. The PWM-signal generation unit outputs the generated drive signals to the corresponding switching elements of the three-phase inverter, to cause the inverter to generate a high-frequency AC voltage.

Abstract: A motor drive control device includes a three-phase rectifier; a boosting circuit including a reactor, a switching element, and a backflow preventing element and boosts a direct-current bus voltage supplied from the three-phase rectifier; a smoothing capacitor; an inverter circuit; a boosting control unit; an inverter control unit; and a circuit protecting unit suppresses a ripple current flowing through the smoothing capacitor. In the circuit protecting unit, a correlation of an on-duty ratio of the switching element included in the boosting circuit, the output power of the inverter circuit, and an estimated ripple current are set. On the basis of the on-duty ratio of the switching element, output power of the inverter circuit, and the correlation, the circuit protecting unit determines an estimated ripple current flowing through the smoothing capacitor. When the estimated ripple current exceeds a preset threshold, the circuit protecting unit suppresses the ripple current.

Abstract: A harmonic current compensator is connected in parallel with a harmonic generating load to a system power supply and supplies a compensation current Ia to limit a harmonic component contained in a load current IL to be input from the system power supply to the harmonic generating load. The harmonic current compensator includes: a load current detector that detects the load current IL; a compensation current detector that detects the supplied compensation current Ia; a control amount computing portion that computes a control amount of the compensation current Ia based on the harmonic component contained in the load current IL detected by the load current detector and the compensation current Ia detected by the compensation current detector; and a limiter that limits an upper limit of the compensation current Ia.

Abstract: A backflow preventing device includes a backflow preventing element that is connected between a power supply and a load and that prevents electric current from flowing backward from the load side toward the power supply side, and a commutating device that performs a commutation operation for causing the electric current to flow to a commutation path connected in parallel with the backflow preventing element. A plurality of elements including at least one or more of elements constituting the commutating device are configured as a module, so that, for example, the device can be reduced in size. Moreover, a simplified heat-dissipation design and a simplified air-duct design can be achieved.

Abstract: Provided is a power conversion device configured to convert electric power from a power source to a load, including: a boosting device including a boost rectification unit configured to prevent backflow of a current from the load side to the power source side, the boosting device being configured to change a voltage of power from the power source to a predetermined voltage based on a drive signal; a commutation device configured to perform commutation operation in which a current flowing through the boosting device is caused to flow into an other path based on a commutation signal; and a signal generating module device configured as a module to generate and send an output signal based on an input signal that is input thereto. The input signal has an on-pulse width greater than a length of time where the output signal generated by the signal generating module device is turned on.

Abstract: A motor drive control apparatus according to the present invention includes: a three-phase rectifier to rectify an AC voltage supplied from a three-phase AC source; a booster circuit including a reactor, a switching element, and a backflow preventing element, to boost a DC bus voltage supplied from the three-phase rectifier; a smoothing capacitor to smooth an output of the booster circuit; and an inverter circuit to convert the DC bus voltage smoothed by the smoothing capacitor into an AC voltage and supplying the AC voltage to a motor. During a starting operation of a boosting operation of the booster circuit or a stopping operation of the boosting operation thereof, a rotation speed of the motor is fixed.

Abstract: Provided is a power converter for converting electric power between a power source and a load, including: a boosting device including a boost rectifier configured to prevent a backflow of a current from the load side to the power source side, the boosting device being configured to change a voltage of electric power supplied from the power source to a predetermined voltage; a commutation device configured to perform a commutation operation of directing a current flowing through the boosting device to another path; and a controller configured to perform control related to the voltage change of the boosting device and control related to the commutation operation of the commutation device, in which the commutation device is configured to flow, when the commutation device performs the commutation operation, a current generating a voltage causing reverse recovery of the boost rectifier to the commutation device side.

Abstract: A backflow preventing device includes a backflow preventing element that is connected between a power supply and a load and that prevents electric current from flowing backward from the load side toward the power supply side, a commutating device that performs a commutation operation for causing the electric current to flow to a commutation path connected in parallel with the backflow preventing element, and a controller that sets a time for performing the commutation operation and causes the commutating device to perform the commutation operation based on the set time. The backflow preventing device has a plurality of the commutation paths and has, for example, elements with small current-carrying capacities disposed in the commutation paths to achieve cost reduction and to cope with, for example, failures, thereby allowing for enhanced reliability for reducing recovery electric current.

Abstract: An air conditioner includes: an outdoor fan provided in an outdoor unit; a permanent magnet synchronous motor that drives the outdoor fan; an inverter that uses a DC power source as a power source and applies a voltage to the permanent magnet synchronous motor; an inverter control means that controls the output voltage of the inverter; and a shunt resist connected between the DC power source and the inverter. If the outdoor fan is rotating due to an external force while the inverter is stopped, the inverter control means causes the inverter to operate using a brake sequence that brakes the rotation of the outdoor fan, and then causes the inverter to operate using a drive sequence that power-drives the outdoor fan.

Abstract: A power conversion device includes: a rectifier, a converter unit including a reactor, a backflow prevention element, and a switching element, the converter unit being configured to boost a DC voltage rectified by the rectifier, a smoothing capacitor, a reactor current detection unit, a bus voltage detection unit, a temperature detection unit, and a control unit. The control unit includes a converter control unit configured to calculate a switching command value for driving the switching element, on the basis of a target command voltage which is the bus voltage to be targeted, the bus voltage detected by the bus voltage detection unit, and the reactor current detected by the reactor current detection unit, and a temperature correction unit configured to correct the temperature of the switching element detected by the temperature detection unit, on the basis of the switching command value calculated by the converter control unit.

Abstract: A power conversion device configured to convert electric power from a power source to a load, the power conversion device including: a voltage boosting device including a boost rectification unit configured to prevent backflow of a current from a side of the load to a side of the power source, the voltage boosting device being configured to change voltage of power from the power source to a predetermined voltage; and a commutation device including a transformer and configured to perform commutation operation, in the commutation operation, the transformer applying a voltage induced by a current flowing through a primary-side winding to a secondary-side winding, which is on an other path different from that for the voltage changing device, wherein the transformer includes at least part of windings that are wound such that an inter-winding distance is uniform.

Abstract: A heat pump device capable of efficiently and reliably preventing a liquid refrigerant from stagnating in a compressor an air conditioner, a heat pump water heater, a refrigerator, and a freezing machine including the heat pump device. The configuration is such that, when the compressor is under operation standby, a high-frequency voltage synchronizing with a carrier signal is supplied to the compressor motor to carry out the locked energization of the compressor motor. From respective inter-phase voltages, respective phase voltages, or respective phase currents of the compressor motor for a plurality of high-frequency energization cycles, the detection values for one high-frequency energization cycle are restored. A power value calculated using the restored detection values for one high-frequency energization cycle is controlled to coincide with a heating power command necessary for discharging the liquid refrigerant stagnated in the compressor to the outside of the compressor.

Abstract: A power conversion apparatus includes a rectifier, a converter including a reactor, a switching element, and a reverse current prevention element, a smoothing capacitor configured to smooth the output voltage, a current detector configured to detect a reactor current, a voltage detector configured to detect the output voltage, and a converter control unit configured to control operation of the switching element of the converter. The converter-control unit includes a switching command calculation unit configured to calculate a switching command value responsive to a ratio of the rectified voltage to the output voltage in accordance with the output voltage and the reactor current, a switching control unit configured to control operation of the switching element in accordance with the switching command value, and a supply abnormality determination unit configured to determine occurrence of a momentary power failure or voltage sag in accordance with the switching command value.