Power conversion device, motor drive control device, blower, compressor, and air conditioner

A power conversion device of an interleaving type, comprising:

• a rectifier rectifying an AC voltage output from an AC power supply;
• a booster circuit boosting an output voltage of the rectifier;
• a controller causing the booster circuit to perform synchronous rectification;
• a smoothing capacitor smoothing an output voltage of the booster circuit;
• a bus voltage detector detecting a bus voltage smoothed by the smoothing capacitor;
• and
• a power supply voltage detector detecting a voltage of the AC power supply, wherein
• the booster circuit is constituted by connecting a plurality of chopper circuits in parallel to each other, the chopper circuits each including an upper arm switching element and a lower arm switching element connected in series to a reactor connected to the rectifier, and
• the controller, in a discontinuous mode, generates a drive pulse causing the upper arm switching element to be turned on when a reverse current flows through the upper arm switching element,
• wherein the controller is configured to:
• calculate a first drive pulse driving the lower arm switching element to cause a current output from the AC power supply to be controlled to have a sine wave form and to cause the bus voltage to have a specific value, based on the bus voltage detected by the bus voltage detector and the power supply voltage detected by the power supply voltage detector;
• and
• calculate a second drive pulse driving the upper arm switching element, based on the bus voltage detected by the bus voltage detector, the power supply voltage detected by the power supply voltage detector, and the first drive pulse, wherein
• the second drive pulse satisfies a relationship of Txb≤Txa×{(Vin−2×Vf−R×i−Ron×i)/(Vout−Vin−2×Vf−R×i−Ron×i)}, where
• Txa represents an ON time of the first drive pulse,
• Txb represents an ON time of the second drive pulse,
• Vin represents an absolute value of an instantaneous voltage of the AC power supply,
• Vf represents a forward drop voltage of a diode constituting the rectifier,
• R represents a resistance of the reactor,
• Ron represents an on-resistance of each of the upper arm switching element and the lower arm switching element,
• Vout represents the bus voltage detected by the bus voltage detector, and
• i represents a current flowing through the reactor.