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 direct-current power supply device includes a rectifier connected to a power supply, a charge storage unit configured by a first capacitor and a second capacitor connected in series, a switching unit configured by a first switching element 4a and a second switching element connected in series and backflow preventing elements that suppress a backflow of electric charges from the charge storage unit, a reactor, a control unit that controls operations of the first switching element and the second switching element, and a direct-current-voltage detecting unit that detects a first both-end voltage, which is a voltage across the first capacitor, and a second both-end voltage, which is a voltage across the second capacitor. The control unit detects, on the basis of a voltage difference between the first both-end voltage and the second both-end voltage, a short-circuit failure of one of the first switching element and the second switching element.

Abstract: A first reactor is provided on the input side of a rectifying circuit that rectifies AC power (on the side of an AC power supply), and on the output side of the rectifying circuit (on the side of a load), first and second capacitors that are connected in series to each other, and first and second switching elements that switch between charging and not charging of the first and second capacitors, respectively, are provided, a second capacitor group in Y-connection, provided with three capacitors, each of which is connected to each phase-terminal of the first reactor on the side of the rectifying circuit, is connected to the midpoint of the first and second switching elements, and the output voltage to the load is boosted, while the on-duty of the first switching element and the on-duty of the second switching element are controlled to be equal to each other.

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 conversion device according to the present invention includes a power supply, a booster unit (a reactor, a switch) that boosts a voltage supplied from the power supply by switching control, a smoothing circuit that smoothes an output voltage from the booster unit, a rectifier that is arranged between the booster unit and the smoothing circuit to prevent a current reverse flow toward the booster unit, and a commutation unit that is connected to the rectifier in parallel to commutate a current flowing through the rectifier toward itself.

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 direct-current power supply device includes a rectifier connected to a power supply, a charge storage unit configured by a first capacitor and a second capacitor connected in series, a switching unit configured by a first switching element 4a and a second switching element connected in series and backflow preventing elements that suppress a backflow of electric charges from the charge storage unit, a reactor, a control unit that controls operations of the first switching element and the second switching element, and a direct-current-voltage detecting unit that detects a first both-end voltage, which is a voltage across the first capacitor, and a second both-end voltage, which is a voltage across the second capacitor. The control unit detects, on the basis of a voltage difference between the first both-end voltage and the second both-end voltage, a short-circuit failure of one of the first switching element and the second switching element.

Abstract: A direct-current power supply device includes a switching unit constituted by a first switching element and a second switching element and a control unit that controls the operations of the first witching element and the second switching element. The switching unit has a first mode in which on-duty is a first value and a second mode in which the on-duty is a second value larger than the first value. When transitioning the switching unit from the first mode to the second mode, the control unit controls the switching unit such that the time until the on-duty reaches the second value is equal to or longer than a fixed time and controls, after the on-duty reaches the second value, an operation cycle of the switching unit to extend the operation cycle.

Abstract: The DC power-supply device includes a rectifier circuit rectifying an alternating current, a reactor connected to an input or output side of the rectifier circuit, a first capacitor and a second capacitor serially connected between output terminals to a load, and a charging unit that selectively charges one or both of the first capacitor and the second capacitor. A ratio, to a period obtained by combining a charging period and a non-charging period of a pair of the first capacitor and the second capacitor, of the non-charging period, is controlled according to an operating condition of the load, to change a charging frequency of the first capacitor and the second capacitor based on the ratio, at the time of controlling an output voltage to the load.

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: To provide a DC power-supply device that can suppress voltage unbalance of a plurality of capacitors serially connected between both terminals of a load, achieve stable drive of the load and long life of the capacitors, and contribute to high reliability, in a configuration in which an alternating current is converted into a direct current and is supplied to a load, and a refrigeration-cycle application device including the DC power-supply device. The DC power-supply device includes a rectifier circuit, a reactor connected to an input or an output side of the rectifier circuit, a first capacitor and a second capacitor serially connected between output terminals to a load, a charging unit that selectively charges one or both of the first capacitor and the second capacitor, and further includes a control unit that controls the charging unit so that voltage unbalance between the first capacitor and the second capacitor is suppressed.

Abstract: A heat pump device that can efficiently feed a high-frequency current to an electric motor and effectively heat a compressor includes a compressor including a compression mechanism configured to compress a refrigerant and a motor configured to drive the compression mechanism, heat exchangers, an inverter configured to apply a voltage to the motor, and an inverter control unit configured to drive the inverter. The inverter control unit includes a stagnation detecting unit configured to determine whether heating of the compressor is necessary and notify the determination result and a high-frequency-alternating-current-voltage generating unit and a PWM-signal generating unit configured to shift to a heating operation mode when the heating is necessary and, in the heating operation mode, generate PWM signals to provide, based on a heating time carrier signal having two or more frequencies, a period in which a reflux current flows.

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 heat pump apparatus, including: a two-cylinder compressor including: an electric motor; two compression units to be driven by the electric motor, the two-cylinder compressor being structured to switch between two operation modes including single operation in which one of the compression units is brought into a non-compression state, and parallel operation in which both the compression units are brought into a compression state; an inverter drive control device supplying drive power to the electric motor of the two-cylinder compressor; an operation mode detecting-determining unit determining a current operation mode based on an electric signal acquired from the inverter drive control device; and a capacity control device determining a rotating frequency of the electric motor so that a temperature of a target object is brought close to a set value, to thereby control the inverter drive control device based on a result of determination of the operation mode detecting-determining unit.

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: A power converter for converting electrical power from a power source to a load, including: a boosting device including a boost rectifier configured to prevent a backflow of a current from the load to the power source, the boosting device being configured to change a voltage of electrical power from the power source to a predetermined voltage; and a commutation device including: a commutation operation device configured to perform a commutation operation of directing a current flowing through the boosting device to an other path; and a commutation rectifier including a plurality of rectifiers and connected in series on the other path, the commutation rectifier being configured to rectify a current relating to commutation, thereby reducing a capacitance component.

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: A power conversion device located between an AC power source and a load includes: a rectifier circuit unit that rectifies a voltage of the AC power source; a smoothing unit that smooths a DC voltage on the load side of the rectifier circuit unit; a short-circuiting unit that short-circuits the AC power source; a step-up reactor—located on the AC power source side of the short-circuiting unit; at least one of a reactor current detecting unit—that detects the current of the step-up reactor and a bus voltage detecting unit that detects an output voltage of the smoothing unit; a counterflow preventing element that prevents a counterflow of the current from the smoothing unit to the AC power source; a switching control unit that outputs a control signal for the short-circuiting unit; and a switching frequency changing unit that changes a frequency of the control signal using a logic operation.

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.