Abstract: Provided is a power conversion device that does not require adaptation work and can suppress a current beat regardless of an operation state of a motor. The power conversion device includes an inverter 1 that converts a DC voltage into an AC voltage and drives an AC motor 2, and beat compensation units 46 and 49 that suppress a current beat component of an output current of the inverter 1. The beat compensation units 46 and 49 include beat extraction units 50, 51, and 52 that calculate beat components of the output current of the inverter 1, and beat compensation voltage calculation units 53 and 54 that estimate beat compensation voltages from the beat components calculated by the beat extraction units 50, 51, and 52. The current beat component of the output current of the inverter 1 is suppressed based on the beat compensation voltages estimated by the beat compensation voltage calculation units 53 and 54.

Abstract: There is provided a synchronous machine control device capable of improving the performance of a motor without complicating a control system. The synchronous machine control device controls a power converter (2) that supplies electric power to a synchronous machine (1). The synchronous machine control device includes a first magnetic flux command computation unit (21) that computes a first magnetic flux command value (?d*, ?q*) from a current command value (Id*, Iq*) of the synchronous machine (1), a magnetic flux estimation unit (23) that estimates a magnetic flux value (?dc, ?qc) of the synchronous machine (1) from a current detection value (Idc, Iqc) of the synchronous machine (1), and a voltage computation unit (19) that creates a voltage command value (Vd*, Vq*) of the power converter such that the first magnetic flux command value (?d*, ?q*) coincides with the magnetic flux value (?dc, ?qc).

Abstract: Provided is a power conversion system that can suppress a fault in a short-circuiting switch that bypasses a fault unit and enhance the reliability and redundancy of the system. The power conversion system is provided with a plurality of power converter units that are formed by using semiconductor switch elements and are connected in series, and comprises: switch elements that are provided to input terminals and/or output terminals of the power converter units and bypass the power converter units; and overvoltage suppressing elements which are connected in parallel with the switch elements and in which conducting states are changed by an application of a prescribed voltage.

Abstract: A motor drive device includes a power conversion circuit that drives an AC motor and a controller that controls the power conversion circuit. The controller includes a command current calculation unit generating a command current according to command torque for the AC motor and a current control unit that performs feedback control for adjusting a current applied to the AC motor to the command current. The controller also includes a control gain setting unit that calculates a control gain used for the feedback control based on the command torque and sets the calculated control gain in the current control unit. The control gain setting unit performs control such that a time from a decrease of an absolute value of the command torque to switching of the control gain is longer than a time from an increase of the absolute value of the command torque to switching of the control gain.

Abstract: Provided is a power conversion device that does not require adaptation work and can suppress a current beat regardless of an operation state of a motor. The power conversion device includes an inverter 1 that converts a DC voltage into an AC voltage and drives an AC motor 2, and beat compensation units 46 and 49 that suppress a current beat component of an output current of the inverter 1. The beat compensation units 46 and 49 include beat extraction units 50, 51, and 52 that calculate beat components of the output current of the inverter 1, and beat compensation voltage calculation units 53 and 54 that estimate beat compensation voltages from the beat components calculated by the beat extraction units 50, 51, and 52. The current beat component of the output current of the inverter 1 is suppressed based on the beat compensation voltages estimated by the beat compensation voltage calculation units 53 and 54.

Abstract: A motor drive device (200) includes: a power conversion circuit (204) that drives an AC motor; and a controller (203) that controls the power conversion circuit. The controller includes: a command current calculation unit (206) that generates a command current according to command torque for the AC motor; a current control unit (208) that performs feedback control for adjusting a current applied to the AC motor to the command current; and a control gain setting unit (207) that calculates a control gain used for the feedback control based on the command torque and sets the calculated control gain in the current control unit. The control gain setting unit performs control such that a time from a decrease of an absolute value of the command torque to switching of the control gain is longer than a time from an increase of the absolute value of the command torque to switching of the control gain. As a result, deterioration of control stability of motor torque during a transient response is avoided.

Abstract: Stable current control is performed even at the time of occurrence of disturbance, while the steadily occurring current pulsation is suppressed. A motor drive device 100 includes a power conversion circuit 103 that drives an alternating-current motor 101, and a controller 102 that controls the power conversion circuit 103. The controller 102 includes a voltage command calculation unit 108, a control state judgement unit 112, and a control gain change unit 113.

Abstract: Stable current control is performed even at the time of occurrence of disturbance, while the steadily occurring current pulsation is suppressed. A motor drive device 100 includes a power conversion circuit 103 that drives an alternating-current motor 101, and a controller 102 that controls the power conversion circuit 103. The controller 102 includes a voltage command calculation unit 108, a control state judgement unit 112, and a control gain change unit 113.