Abstract: A power conversion device includes an inverter configured by arms including phase upper-arm switching elements and phase lower-arm switching elements, a power-supply shunt resistor, lower-arm shunt resistors, and a control unit that generates drive signals corresponding to the phase upper-arm switching elements and the phase lower-arm switching elements from detection values of the voltage detectors. The power conversion device changes a ratio of time in which all of the upper-arm switching elements are in an ON state and time in which all of the lower-arm switching elements are in the ON state in one cycle of switching of the inverter according to a modulation ratio.

Abstract: A switch device in a power conversion device is located between a power supply and a load, wherein the power conversion device includes a shunt resistance and a switching element and is capable of executing stable control, the switch device includes a switching element that includes a gate terminal, a gate drive circuit that applies a drive voltage Vcc to a gate terminal of the switching element, and a control unit that generates a drive signal to the gate drive circuit, wherein a value obtained by subtracting a threshold voltage Vth of the switching element from the drive voltage Vcc to be applied to the gate terminal of the switching element is greater than a product of a resistance value Rsh+Rdc from an emitter of the switching element to a negative electrode of the gate drive circuit and a maximum current value Ipeak that flows through the switching element.

Abstract: An outdoor device of an air conditioner includes a compressor, an outdoor fan, and an outdoor control board. The outdoor device includes: a control unit that controls the compressor and the outdoor fan; and a temperature detector that detects an ambient temperature of an electric component provided on the outdoor control board. The control unit, when the compressor is stopped, stops the outdoor fan and then determines whether a temperature detected by the temperature detector is equal to or higher than a threshold, and, when it is determined that the temperature detected by the temperature detector is equal to or higher than the threshold, operates the outdoor fan at a protective rotation number that is lower than a rotation number of the outdoor fan while the compressor is in operation so as to circulate air, thereby cooling the outdoor control board.

Abstract: A power conversion device includes a power-supply shunt resistance that is provided between an inverter and the negative-voltage side of a DC power supply, and respective-phase lower-arm shunt resistances that are provided between the power-supply shunt resistance and respective-phase lower-arm switching elements. Respective-phase lower-arm voltages, that are respective voltages between the negative-voltage side of the DC power supply and connection points between the respective-phase lower-arm switching elements and the respective-phase lower-arm shunt resistances, are detected to calculate respective-phase currents that flow through a load device in accordance with detection values of the respective-phase lower-arm voltages, and to control a carrier frequency of a carrier signal, which serves as a reference frequency of each drive signal, according to a change in a specific control parameter A.

Abstract: A power conversion device is configured to have reactors and is configured to have chopper circuit units, connected in series, that chop the output of a rectifier configured to rectify an AC voltage from an AC power supply. The power conversion device includes: an AC switch disposed on a side closer to the AC power supply than the chopper circuit units; an AC reactor that is connected in parallel to the AC switch; and a switching control unit that stops the switching of the switching elements when the contact of the AC switch is open.

Abstract: The power conversion device includes a power-supply shunt resistance provided between an inverter and the negative-voltage side of a DC power supply, respective-phase lower-arm shunt resistances provided between the power-supply shunt resistance and respective-phase lower-arm switching elements, a first overcurrent detection unit performing overcurrent detection on a current that flows through the power-supply shunt resistance on the basis of a power-supply shunt-resistance voltage, and a second overcurrent detection unit performing overcurrent detection on each current that flows through the respective-phase lower-arm shunt resistances on the basis of respective-phase lower-arm voltages, wherein overcurrent detection is performed on each phase current using either one of the overcurrent detection result of the first overcurrent detection unit and the overcurrent detection result of the second overcurrent detection unit.

Abstract: The power conversion device includes a power-supply shunt resistor provided between a negative voltage side of a DC power supply and an inverter and phase lower-arm shunt resistors respectively provided between phase lower-arm switching elements of two arms among three arms and the power-supply shunt resistor. The power conversion device detects voltages between connection points of the phase lower-arm switching elements and the phase lower-arm shunt resistors and a negative voltage side of the DC power supply and calculates, on the basis of detection values of the voltages, phase currents flowing to a load device.

Abstract: A power converter includes step-up means for varying a voltage applied by a power supply to a predetermined voltage, commutating means for performing a commutation operation for allowing a current flowing through the step-up means to flow through a second path, smoothing means for smoothing a voltage related to outputs of the step-up means and the commutating means to produce power and supplying the power to a load side, and control means for performing control related to voltage varying, such as stepping up, by the step-up means and controlling the commutation operation of the commutating means on the basis of at least one of a voltage and a current related to the step-up means.

Abstract: A power conversion device includes a switching control unit that controls respective switching elements constituting a plurality of chopper circuits, a rectified-voltage detection unit, a bus-bar voltage detection unit, and a bus-bar current detection unit. The switching control unit includes an on-duty calculation unit that calculates a reference on-duty of respective drive pulses with respect to the switching elements based on a bus-bar voltage and a bus-bar current, an on-duty correction unit that corrects the reference on-duty to output on-duties of the respective drive pulses based on the bus-bar current, so that change amounts of respective reactor currents become substantially the same, and a drive-pulse generation unit that generates the respective drive pulses, based on the respective on-duties.

Abstract: A power converter includes step-up means for varying a voltage applied by a power supply to a predetermined voltage, commutating means for performing a commutation operation for allowing a current flowing through the step-up means to flow through a second path, smoothing means for smoothing a voltage related to outputs of the step-up means and the commutating means to produce power and supplying the power to a load side, and control means for performing control related to voltage varying, such as stepping up, by the step-up means and controlling the commutation operation of the commutating means on the basis of at least one of a voltage and a current related to the step-up means.