Electric motor drive device and air conditioner

An electric motor drive device comprising:

• a three-phase diode bridge to rectify a three-phase alternating-current (AC) voltage, to convert the AC voltage into a direct-current (DC) voltage;
• a smoothing capacitor to smooth the DC voltage;
• a DC reactor provided between the three-phase diode bridge and the smoothing capacitor;
• an inverter to convert the DC voltage smoothed by the smoothing capacitor into an AC voltage, and output the AC voltage to a motor;
• a voltage detector to detect a DC voltage output from the three-phase diode bridge;
• an inverter controller to detect an imbalanced state of the three-phase AC voltage based on a DC voltage value, and control the inverter based on a detection result of the imbalanced state, the DC voltage value being a detection value of the DC voltage obtained by the voltage detector, and
• a zero-cross point detector to detect a zero-cross point of any one phase of the three-phase AC voltage, wherein
• the inverter controller detects an imbalanced state of the three-phase AC voltage based on the DC voltage value and the zero-cross point detected by the zero-cross point detector.