Abstract: In order to achieve a power conversion device with which a motor can be stably driven, a power conversion device is provided with: an inverter, which converts supplied DC voltage to an AC output voltage and supplies the AC output voltage to windings, and which, in accordance with the DC voltage, changes the saturation level at which the output voltage is saturated, in order to drive a motor equipped with a stator having the windings and a rotor having permanent magnets; and a controller which, when the output voltage is lower than the saturation level, increases the output current of the inverter such that a magnetic flux that weakens or strengthens the magnetic flux generated by the permanent magnets is generated in the windings. An air conditioner including the power conversion device is also disclosed.

Abstract: A motor drive that enables the elimination of distortion of a motor current caused by direct current voltage ripples with the use of a smoothing capacitor having a small capacity and refrigeration equipment. A motor drive includes a rectifier circuit, a smoothing capacitor, voltage detector, an inverter circuit, current sensor, and a controller configured to control the inverter circuit. The controller has a voltage controller configured to generate a voltage command value used for controlling the motor, a ripple frequency arithmetic unit configured to operate a ripple frequency included in the direct current voltage signal, and a harmonic suppressor configured to process a signal based on the direct current signal using an S controller having a gain near the ripple frequency and output a corrected amount. The inverter circuit is controlled based on a signal that the voltage command value is corrected using the corrected amount.

Abstract: In order to achieve a power conversion device with which a motor can be stably driven, a power conversion device is provided with: an inverter, which converts supplied DC voltage to an AC output voltage and supplies the AC output voltage to windings, and which, in accordance with the DC voltage, changes the saturation level at which the output voltage is saturated, in order to drive a motor equipped with a stator having the windings and a rotor having permanent magnets; and a controller which, when the output voltage is lower than the saturation level, increases the output current of the inverter such that a magnetic flux that weakens or strengthens the magnetic flux generated by the permanent magnets is generated in the windings. An air conditioner including the power conversion device is also disclosed.

Abstract: A motor drive that enables the elimination of distortion of a motor current caused by direct current voltage ripples with the use of a smoothing capacitor having a small capacity and refrigeration equipment. A motor drive includes a rectifier circuit, a smoothing capacitor, voltage detector, an inverter circuit, current sensor, and a controller configured to control the inverter circuit. The controller has a voltage controller configured to generate a voltage command value used for controlling the motor, a ripple frequency arithmetic unit configured to operate a ripple frequency included in the direct current voltage signal, and a harmonic suppressor configured to process a signal based on the direct current signal using an S controller having a gain near the ripple frequency and output a corrected amount. The inverter circuit is controlled based on a signal that the voltage command value is corrected using the corrected amount.