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: 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 converting apparatus outputs an alternating-current power to drive an electric motor, and includes: a switching circuit that converts an input direct-current power to an alternating-current power based on driving of MOS-FETs and outputs the alternating-current power; and a driving control unit capable of controlling a carrier frequency and controlling the driving of the MOS-FETs. The driving control unit controls the carrier frequency on the basis of a noise level of a carrier noise obtained by combining noises that occur in the electric motor and the power converting apparatus due to the driving of the MOS-FETs at the carrier frequency and a noise level of driving noises from a plurality of noise sources that occur irrespective of the carrier frequency in the same housing in which the power converting apparatus and the electric motor are contained.

Abstract: A power supply switching device and switch board checks whether or not a primary-side voltage of a remote shutoff breaker and a secondary-side voltage thereof become a rated voltage after a commercial power system is recovered from a blackout. Next, when both primary-side voltage and secondary-side voltage become the rated voltage, a contactor is actuated to interconnect a home power system with the commercial power system. Hence, charging of the home power system without causing a user to notice such a charging upon recovery of the commercial power system from a blackout can be prevented. As a result, the safety for the user can be ensured.

Abstract: A drive device driving a power converter that includes a switching element formed from a wide bandgap semiconductor, includes a PWM-signal output unit that generates a drive signal that drives the switching element with PWM; an on-speed reducing unit that, when the switching element is changed from off to on, reduces a change rate of the drive signal; and an off-speed improving unit that, when the switching element is changed from on to off, draws charge from the switching element at a high speed and with a charge drawing performance higher than that at a time when the switching element is changed from off to on.

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 leak-current detecting unit detects a zero-phase current flowing from an electric-motor driving device, which drives an electric motor with electric power from an alternating-current power supply, or the electric motor to a ground, a leak-current control unit that, on the basis of the zero-phase current detected by the leak-current detecting unit, generates a control signal having cyclicity synchronized with the alternating-current power supply, and an anti-phase generating unit that generates an anti-phase current that is in anti-phase to the zero-phase current on the basis of the control signal from the leak-current control unit, and outputs the anti-phase current.

Abstract: The present invention includes a plurality of fan motors, first and second inverters for individually driving the fan motors, respectively, and one and a common control unit that performs a control arithmetic for each of the fan motors and generates an individual driving signal given to each of the inverters.

Abstract: A motor drive apparatus driving a motor as a three-phase motor converting direct power into three-phase alternating power, includes: inverter modules equivalent in number to phases of the motor; and a control unit generating PWM signals used to drive the inverter modules with PWM. The inverter modules each include a plurality of switching element pairs connected in parallel, each of the switching element pairs including two switching elements connected in series.

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 motor drive apparatus driving a motor as a three-phase motor converting direct current into three-phase alternating current, includes: inverter modules and equivalent in number to phases of the motor; and a control unit generating PWM signals used to drive the inverter modules with PWM. The inverter modules each include a plurality of switching element pairs connected in parallel, each of the switching element pairs including two switching elements connected in series.

Abstract: A power conversion apparatus includes: an inverter to drive a motor, using a first carrier signal; an inverter connected in parallel to the inverter, to drive a motor, using a second carrier signal; respective phase lower arm shunt resistors to detect a first current flowing inside the inverter; respective phase lower arm shunt resistors to detect a second current flowing in the inverter; and a control unit to control the inverters. A phase difference is set between the first carrier signal and the second carrier signal to prevent a detection period for the first current in the first carrier signal and a detection period for the second current in the second carrier signal from overlapping each other when the inverters are controlled.

Abstract: A heat pump apparatus includes a compressor compressing a refrigerant, a motor driving the compressor, an inverter device, and an inverter control unit controlling the inverter device. The inverter device includes the same number of bridge circuits as those of phases of the motor, and each of the bridge circuits includes plural pairs of series-connected switching elements. The pairs of switching elements are connected in parallel. The inverter device applies to the motor a high-frequency voltage of a frequency at which the motor does not rotate.

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: 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: A power converting apparatus outputs an alternating-current power to drive an electric motor, and includes: a switching circuit that converts an input direct-current power to an alternating-current power based on driving of MOS-FETs and outputs the alternating-current power; and a driving control unit capable of controlling a carrier frequency and controlling the driving of the MOS-FETs. The driving control unit controls the carrier frequency on the basis of a noise level of a carrier noise obtained by combining noises that occur in the electric motor and the power converting apparatus due to the driving of the MOS-FETs at the carrier frequency and a noise level of driving noises from a plurality of noise sources that occur irrespective of the carrier frequency in the same housing in which the power converting apparatus and the electric motor are contained.

Abstract: A charging/discharging device includes a charging/discharging connector that electrically connects a storage battery and the charging/discharging device, a cable that is connected to the charging/discharging connector at one end and is connected to the charging/discharging device at the other end, a power conversion unit, a control unit that controls an operation of the power conversion unit, and an abnormality detection unit that outputs an abnormality detection signal for stopping an operation of the power conversion unit to at least any of the control unit and the power conversion unit, when an output from a comparator and an ON signal from the control unit are input to an AND circuit.

Abstract: A direct-current power supply device is a direct-current power supply device that converts a three-phase alternating current to a direct current and supplies the direct current to a load, and includes a first capacitor and a second capacitor connected in series between output terminals to the load, a charge unit that selectively charges one or both of the first capacitor and the second capacitor, and a control unit that controls the charge unit. The control unit controls an output voltage of the direct-current power supply device by a charging period of the charge unit, and also controls a power factor and a harmonic current of the direct-current power supply device by a charge timing with respect to a reference phase of the three-phase alternating current of the charge unit as a reference.

Abstract: A power conversion device includes a rectifier circuit that converts an AC power from an AC power supply, into a DC power, a short-circuit unit that short-circuits the AC power supply via a reactor connected between the AC power supply and the rectifier circuit, a control unit that generates a plurality of drive signals to control the short-circuit unit in a half cycle of the AC power supply, and a smoothing capacitor. The control unit stepwise varies threshold values that limit a value of a power-supply current of the AC power supply, in an on-section or an off-section of the plurality of drive signals.

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.