Motor control device and air conditioner

An air conditioner comprising:

• a heat pump system including a compressor, an outdoor side heat exchanger, a decompressor and an indoor side heat exchanger;
• an inverter circuit configured to on-off controlling a plurality of three-phase bridge-connected switching elements according to a predetermined PWM signal pattern, thereby converting a direct current to a three-phase alternating current;
• a current detecting element connected to the direct current side to generate a signal corresponding to a current value;
• a rotor position determination unit configured to determine a rotor position based on phase currents of an electric motor configuring the compressor and driven by the inverter circuit;
• a PWM signal generation unit configured to generate a three-phase PWM signal pattern so that the pattern follows the rotor position;
• a current detection unit configured to detect the phase currents based on a signal generated by the current detecting element and the PWM signal pattern,
• wherein the PWM signal generation unit is configured to increase/decrease a duty in both directions of phase lag side and phase lead side with reference to any phase of the carrier-wave period regarding a first phase of the three-phase PWM signal pattern;
• wherein the PWM signal generation unit is configured to increase/decrease a duty in one of the directions of phase lag side and phase lead side with reference to any phase of the carrier-wave period regarding a second phase of the three-phase PWM signal pattern;
• wherein the PWM signal generation unit is configured to increase/decrease a duty in a direction opposite to the direction of the second phase with reference to any phase of the carrier-wave period regarding a third phase of the three-phase PWM signal pattern;
• and
• wherein the current detection unit has a timing point adjusting unit configured to detect two-phase currents at timing points fixed in the carrier-wave period of the PWM signal and to adjust a detection timing point so that the current is detectable at a variable timing point according to a magnitude of an output voltage supplied to the inverter circuit regarding at least one phase when the two-phase currents become undetectable at the fixed timing points.