Abstract: A power converting apparatus includes a rectifier unit that rectifies a supply voltage applied from a commercial power supply, a capacitor connected to an output end of the rectifier unit, an inverter that converts direct-current power output from the capacitor into alternating-current power and outputs the alternating-current power to a device including a motor, current detection units that detect a power state of the capacitor, and a control unit that performs, by controlling the inverter, load pulsation compensation and power-supply pulsation compensation and adjusts a degree of at least one of the load pulsation compensation and the power-supply pulsation compensation on a basis of detection values of the current detection units. The load pulsation compensation is performed to compensate a load pulsation in a load unit including the inverter and the device. The power-supply pulsation compensation is performed to compensate a power-supply pulsation in the load unit.

Abstract: A power conversion device includes a converter that rectifies a first alternating-current power supplied from an alternating-current power supply and boosts a voltage of the power rectified; a smoothing unit connected to an output end of the converter; and a control unit that controls the converter to cause an input current to the converter to change in accordance with at least one of a first frequency or a second frequency, and that reduces a current flowing to the smoothing unit, the first frequency being a frequency of pulsation of input power to a load unit connected across the smoothing unit, the second frequency being a frequency of pulsation of input power to the converter due to a frequency of the alternating-current power supply.

Abstract: The power converting apparatus includes a rectifier unit rectifying first alternating-current power, a capacitor connected to the rectifier unit, an inverter connected across the capacitor to output second alternating-current power to a motor, a voltage detection unit detecting a power state of the capacitor, and a control unit controlling operations of the inverter and the motor, using a dq-rotational coordinate system rotating in synchronization with a rotor position of the motor. The control unit superimposes a q-axis current pulsation on a drive pattern of the motor in accordance with a detection value of the voltage detection unit to reduce a charge-discharge current of the capacitor, and to cause a d-axis current to the motor to pulsate in synchronization with a frequency that is a positive integer multiple of a frequency of the q-axis current pulsation saturation of a voltage of the inverter.

Abstract: A power converter includes: a rectifier unit that rectifies a power supply voltage applied from a commercial power supply; a capacitor connected to an output end of the rectifier unit; an inverter that converts direct-current power output from the capacitor into alternating-current power and outputs the alternating-current power to a device equipped with a motor; and a control unit that performs power supply ripple compensation control of reducing ripple of a capacitor current, which is a charge/discharge current of the capacitor, by controlling the inverter. The control unit determines whether or not a compensation operation by the power supply ripple compensation control is normal and, when determining that the compensation operation is not normal, performs control of reducing a drive speed of the motor or stopping driving of the motor.

Abstract: A power converter includes a capacitor connected to an output end of a rectifier unit that rectifies first AC power, an inverter that is connected across the capacitor and generates second AC power for output to a motor, and a control unit that controls the operation of the inverter such that pulsation according to the power state of the capacitor is superimposed on a drive pattern of the motor. The control unit performs load pulsation compensation control to reduce the vibration of the motor and power pulsation compensation control to reduce the charging and discharging current of the capacitor while preferentially performing constant current load control to control the rotational speed of the motor, and generates a torque current command for the load pulsation compensation control such that a torque current command allocatable to the power pulsation compensation control remains.

Abstract: A direct current power supply device includes a rectifier circuit that rectifies alternating current power supplied from an alternating current power supply and converts the alternating current power into direct current power, a charge storage unit that includes a function of storing a charge, a charger that charges the charge storage unit, and a heat sink. The charger includes a positive-side switching element, a negative-side switching element, a positive-side backflow prevention diode, and a negative-side backflow prevention diode. The positive-side switching element, the negative-side switching element, the positive-side backflow prevention diode, and the negative-side backflow prevention diode are discrete semiconductor elements. The negative-side backflow prevention diode is a full mold package element. The positive-side switching element, the negative-side switching element, and the positive-side backflow prevention diode are elements that are not full mold packages.

Abstract: A power conversion apparatus includes: a reactor; a rectifier circuit that includes a first leg including switching elements connected in series and a second leg connected in parallel with the first leg, including switching elements connected in series; and a smoothing capacitor that smooths an output voltage of the rectifier circuit. The power conversion apparatus also includes an inverter that converts a direct-current voltage smoothed by the smoothing capacitor into a drive voltage for a motor and applies the drive voltage to the motor; a voltage detection unit that detects the direct-current voltage; and a control unit that controls operation of the rectifier circuit and the inverter. The control unit controls operations of the switching elements on the basis of an induced voltage induced in the motor and a detected value of the direct-current voltage.

Abstract: A DC power supply device includes: a rectifier circuit; a reactor connected at one end to one output terminal of the rectifier circuit; a charging unit including a first and second switching element connected in series between another end of the reactor and another output terminal of the rectifier circuit, the charging unit configured to charge a first and second capacitor connected in series between output terminals to which a load is connected; and a control unit that controls the charging unit. The control unit sets, based on the timing at which the zero-crossing occurs, a dead time in which both the and second switching element are off, and when states of the first and second switching element at a time of occurrence of the zero-crossing match a predetermined set of states, reverses the states of the first switching element and the second switching element.

Abstract: A power converter includes a converter, a smoothing capacitor, an inverter, and a single calculator. The converter includes a switching element and rectifies a power supply voltage applied from an alternating-current power supply. The smoothing capacitor smooths a rectified voltage output from the converter into a direct-current voltage including a ripple. The inverter converts the direct-current voltage smoothed by the smoothing capacitor into an alternating-current voltage for a motor. The calculator performs control such that a first physical quantity representing an operation state of the converter is equal to a second physical quantity representing an operation state of the inverter.

Abstract: A motor drive system includes: an inverter that drives a motor; a current detector that detects and outputs the first signal that is a current value of a current flowing through the inverter; a first low-pass filter that removes a noise frequency component from the first signal and outputs a second signal that is a current value after the noise frequency component has been removed; a demagnetization current determiner that compares a demagnetization current threshold with the second signal, and outputs a demagnetization protection signal when the second signal takes a value larger than the demagnetization current threshold; and a short circuit determiner that compares a third signal with a short circuit and outputs an anomaly signal for stopping the inverter when the third signal takes a value larger than or equal to the short circuit threshold.

Abstract: A power converter includes a converter circuit, a capacitor, and an inverter circuit. The converter circuit includes diodes that are connected in a half-bridge configuration. An alternating-current input end of the converter circuit is connected to one side of an alternating-current power supply. The inverter circuit includes semiconductor switching elements that are connected in a three-phase bridge configuration. An alternating-current output end of the inverter circuit is connected to a motor as a load, and an alternating-current output end is further connected to another side of the alternating-current power supply.

Abstract: A DC power supply device includes a booster circuit generating boosted voltage obtained by boosting DC voltage output from a rectifier circuit and applying the boosted voltage to an inverter circuit, a control unit controlling operation of the booster circuit, and a current detection unit detecting current flowing into and from the inverter circuit. The booster circuit includes a charge accumulation unit including first and second capacitors connected in series and first and second switching elements connected in series. The booster circuit includes a switching unit including backflow prevention elements for preventing backflow of charges from the charge accumulation unit and a current detection unit detecting current flowing into and from the booster circuit. The control unit determines whether to continue driving of an electric motor based on each of detection values of the current detection units.

Abstract: A motor drive apparatus includes: a dq-axis current controller converting phase current flowing through a synchronous motor into d-axis current and q-axis current, and controlling the phase current by determining a voltage command based on the d-axis current and a d-axis current command as well as the q-axis current and a q-axis current command; a voltage amplitude calculating unit obtaining voltage amplitude; a speed controller controlling rotational speed of the motor by determining the q-axis current command based on a speed command, the rotational speed, and a speed droop amount that reduces the speed command; a flux weakening controller performing flux control to limit amplitude of voltage output to the motor by determining the d-axis current command based on the voltage amplitude and a first voltage limit value; and a speed droop controller controlling the speed droop amount based on the voltage amplitude and a second voltage limit value.

Abstract: An estimation device includes a phase current determination unit, a time difference calculation unit, and an estimation unit. The phase current determination unit performs a determination process for determining values of phase currents based on the value of the bus current detected by a bus current detection unit and states of gate pulse signals. The time difference calculation unit calculates a difference between a detection time of the bus current used in a previous determination process and a detection time of the bus current used in a present determination process. The estimation unit estimates at least one of a position and a speed of an AC motor based on the values of the phase currents determined by the phase current determination unit and the difference calculated by the time difference calculation unit.

Abstract: A motor drive device: a power conversion unit; a current detection unit that detects a phase current of the alternating-current motor; a position/speed specifying unit that specifies a magnetic pole position and a rotational speed of the alternating-current motor; a d-axis current pulsation generating unit that generates a d-axis current pulsation command based on q-axis current pulsation or a q-axis current pulsation command, which being in synchronization with the q-axis current pulsation or the q-axis current pulsation command and preventing or reducing an increase or decrease in amplitude of the voltage command; and a dq-axis current control unit that generates the voltage command for controlling the phase current on the dq rotating coordinates, which rotate in synchronization with the magnetic pole position, by using the magnetic pole position, the rotational speed, the phase current, the q-axis current pulsation or the q-axis current pulsation command, and the d-axis current pulsation command.

Abstract: A speed estimating device for an AC motor includes: a model deviation computing unit computing a model deviation based on a voltage, a current, and an estimated angular velocity of the AC motor; a first angular velocity estimating unit computing a first estimated angular velocity based on the model deviation; a second angular velocity estimating unit computing a second estimated angular velocity differing from the first estimated angular velocity in frequency, based on the model deviation; a compensation phase computing unit computing a compensation phase based on a disturbance frequency; and an estimated angular velocity calculator computing an estimated angular velocity of the AC motor based on the first estimated angular velocity and the second estimated angular velocity. Either one of the first estimated angular velocity and the second estimated angular velocity is computed based on the compensation phase.

Abstract: A power conversion apparatus includes: a reactor; a rectifier circuit that includes a first leg including switching elements connected in series and a second leg connected in parallel with the first leg, including switching elements connected in series; and a smoothing capacitor that smooths an output voltage of the rectifier circuit. The power conversion apparatus also includes an inverter that converts a direct-current voltage smoothed by the smoothing capacitor into a drive voltage for a motor and applies the drive voltage to the motor; a voltage detection unit that detects the direct-current voltage; and a control unit that controls operation of the rectifier circuit and the inverter. The control unit controls operations of the switching elements on the basis of an induced voltage induced in the motor and a detected value of the direct-current voltage.

Abstract: A motor drive apparatus includes: a dq-axis current controller converting phase current flowing through a synchronous motor into d-axis current and q-axis current, and controlling the phase current by determining a voltage command based on the d-axis current and a d-axis current command as well as the q-axis current and a q-axis current command; a voltage amplitude calculating unit obtaining voltage amplitude; a speed controller controlling rotational speed of the motor by determining the q-axis current command based on a speed command, the rotational speed, and a speed droop amount that reduces the speed command; a flux weakening controller performing flux control to limit amplitude of voltage output to the motor by determining the d-axis current command based on the voltage amplitude and a first voltage limit value; and a speed droop controller controlling the speed droop amount based on the voltage amplitude and a second voltage limit value.

Abstract: A motor drive system includes: an inverter that drives a motor; a current detector that detects and outputs the first signal that is a current value of a current flowing through the inverter; a first low-pass filter that removes a noise frequency component from the first signal and outputs a second signal that is a current value after the noise frequency component has been removed; a demagnetization current determiner that compares a demagnetization current threshold with the second signal, and outputs a demagnetization protection signal when the second signal takes a value larger than the demagnetization current threshold; and a short circuit determiner that compares a third signal with a short circuit and outputs an anomaly signal for stopping the inverter when the third signal takes a value larger than or equal to the short circuit threshold.

Abstract: An estimation device includes a phase current determination unit, a time difference calculation unit, and an estimation unit. The phase current determination unit performs a determination process for determining values of phase currents based on the value of the bus current detected by a bus current detection unit and states of gate pulse signals. The time difference calculation unit calculates a difference between a detection time of the bus current used in a previous determination process and a detection time of the bus current used in a present determination process. The estimation unit estimates at least one of a position and a speed of an AC motor based on the values of the phase currents determined by the phase current determination unit and the difference calculated by the time difference calculation unit.