Converter, inverter, AC motor driving apparatus, and air conditioner using the same

An inverter comprising:

• an inverter circuit comprising an upper switch element and a lower switch element connected in series to the upper switch element, the inverter circuit connected to an alternating current (AC) motor;
• a current detecting section configured to detect current flowing through the inverter circuit;
• and
• a diagnostic device configured to:
• determine an abnormality of the inverter circuit by controlling turn-on and turn-off of the upper switch element and the lower switch element,
• turn on or turn off the upper switch element and the lower switch element,
• diagnose a short-circuit fault of the AC motor or a short-circuit fault of connection of the inverter circuit to the AC motor based on the current obtained from the current detecting section, and
• diagnose an open-circuit fault of each of the upper and lower switch elements based on a measurement result pattern of the current detected by the current detecting section.

An alternating current (AC) motor driving apparatus comprising:

• a converter circuit configured to convert an AC voltage output by an AC power supply to a direct current (DC) voltage;
• an inverter circuit configured to convert a DC voltage output from the converter circuit to an AC voltage by using a switch element, the inverter circuit connected to an AC motor;
• and
• a diagnostic device configured to diagnose an abnormality of the converter circuit, an abnormality of the inverter circuit, an open-circuit fault of the switch element of the inverter circuit, an abnormality of the AC motor, or an abnormality of a connection between the inverter circuit and the AC motor.

An air conditioner comprising:

• a converter circuit comprising:
• a rectifying section configured to rectify an alternating current (AC) voltage, and
• a smoothing section configured to smooth a direct voltage (DC) voltage rectified by the rectifying section;
• an inrush current preventing section configured to prevent an inrush current from being supplied into the smoothing section;
• a switching section configured to supply the AC voltage to the converter circuit through a path different from a voltage supply path of the inrush current preventing section;
• and
• a diagnostic device configured to:
• diagnose an abnormality of the converter circuit, and
• determine an abnormal region of the converter circuit by controlling the inrush current preventing section and the switching section.