Abstract: A motor driving device includes an inverter that supplies alternating-current voltage to a motor whose speed is variable due to a load variation caused by a compressor, and a control device. The control device includes a frequency estimation unit estimating a frequency estimation value indicating a rotation of the motor, a speed controlling unit generating a first torque current command value based on a deviation between the frequency estimation value and a frequency command value, a load torque estimation unit estimating a load torque applied to the motor, a compensation value calculation unit calculating a torque current compensation value based on the load torque, where the torque current compensation value causes the motor to accelerate in a period including timing of the maximum load torque, and an adding unit generating a second torque current command value based on the first torque current command and torque current compensation values.

Abstract: A motor driving device includes an inverter and a controller, and the inverter has first switching elements of an upper arm, first freewheeling diodes, second switching elements of a lower arm, and second freewheeling diodes. The controller outputs a control signal for setting all of the second switching elements of the lower arm in an ON state when an open failure of any one of the first switching elements of the upper arm is detected, and outputs a control signal for setting all of the plurality of first switching elements of the upper arm in the ON state when an open failure of any one of the second switching elements of the lower arm is detected.

Abstract: A power conversion apparatus includes: a converter that rectifies a power-supply voltage applied from an AC power supply; a capacitor connected to an output end of the converter; an inverter connected across the capacitor; and a control device that performs vibration reduction control of reducing vibration of a compressor by controlling an operation of the inverter. The control device includes: a ?-axis current compensation unit that reduces pulsation of a capacitor output current output from the capacitor to the inverter; and a ?-axis current compensation limiting unit that limits an excitation current compensation value generated by the ?-axis current compensation unit so as to reduce a harmonic component included in a power-supply current flowing between the AC power supply and the converter.

Abstract: A power converter includes a converter that rectifies a power supply voltage applied from an alternating current power supply, a capacitor connected to an output end of the converter, an inverter connected across the capacitor, and a controller that controls an operation of the inverter. The controller performs first control of reducing vibration of a compressor and performs second control of reducing a ripple component of a capacitor output current that is output from the capacitor to the inverter. The second control is control for causing a loss in a motor.

Abstract: A power conversion apparatus includes a converter that rectifies a power-supply voltage applied from an AC power supply, a capacitor connected to an output end of the converter, an inverter connected across the capacitor, and a control device that controls an operation of the inverter. The control device performs a first control of reducing a pulsatile component of a capacitor output current output from the capacitor to the inverter when the load is driven. The first control is control of causing the motor to generate a loss, and the loss that the motor is caused to generate is performed by using a y-axis current.

Abstract: In a control device performing PWM control over an inverter for driving a motor, voltage command values are generated using voltage values obtained by performing proportional and integral calculation on current deviations and non-interference control during normal operation, and the voltage command values are generated without using the result of the integral calculation and performing only the non-interference control, at the time of over-modulation. Moreover, the voltage command values are corrected based on a modulation factor. A correction coefficient is so determined that the AC voltages applied to the motor become close to values proportional to the modulation factor. The motor can be operated over a wide range within an over-modulation range.