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.

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 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 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 motor drive system can detect a misconnection. A motor drive system for driving a motor including a plurality of stator windings includes: an inverter that converts a DC voltage supplied from a DC voltage source into an AC voltage and applies the AC voltage to the motor; a connection switching device that is disposed between the inverter and the motor and can switch a connection state of the stator windings; and a controller that performs abnormality determination on a connection state of the connection switching device on the basis of a current value of a current flowing in each of the stator windings.

Abstract: A converter device includes a rectifier circuit to rectify an AC voltage output from an AC power supply, a booster circuit including a plurality of reactors, a plurality of switching elements, and a plurality of backflow prevention elements to boost an output voltage of the rectifier circuit, a smoothing capacitor to smooth an output voltage of the booster circuit, a bus-current detection circuit to detect a value of a current that flows between the rectifier circuit and the booster circuit, a first filter circuit having a first filter time constant, a second filter circuit having a second filter time constant shorter than the first filter time constant, and a control unit to control an operation of the switching elements as a current value detected by the bus-current detection circuit is input to the control unit via the first filter circuit and the second filter circuit.

Abstract: A synchronous motor control device includes: a DC power supply; an inverter main circuit; a three-phase synchronous motor; and an inverter control unit that outputs a PWM signal used to control the inverter main circuit. The inverter control unit includes: a PWM signal generation unit; a start-up control unit that outputs a start-up voltage command value to the PWM signal generation unit at the time of start-up; a steady state control unit that calculates a steady state voltage command value in a steady state and outputs the value to the PWM signal generation unit; and a steady state control parameter initial value calculation unit that outputs an initial value of a control parameter to the steady state control unit such that an output voltage vector from the inverter main circuit to the three-phase synchronous motor is consistent before and after switching from the start-up to the steady state.