Air conditioner

An air conditioner comprising a refrigerating cycle composed of at least a compressor;

• an electric motor to be used as a power source of said compressor;
• an electric driving circuit (an inverter) for driving said electric motor;
• a in-room heat exchanger;
• an electrically operated expansion valve;
• and an out-room heat exchanger, a flow rate of a refrigerant circulating in said refrigerating cycle being controlled by changing rotating speed of said electric motor and an opening degree of said electrically operated expansion valve, wherein
• said electric motor comprises:
• a stator having a primary winding and a rotor having a field magnet, said field magnet comprising a first field magnet having different polarity magnetic poles sequentially arranged in a rotating direction and a second field magnet having different polarity magnetic poles sequentially arranged in a rotating direction, said second field magnet being capable of rotating relative to said first field magnet, said first and said second field magnets being opposite to magnetic poles of said stator;
• and
• a mechanism for changing a phase of a composite magnetic pole of said first and said second field magnets with respect to the magnetic pole of said first field magnet depending on a direction of torque, said mechanism for changing depending on a direction of torque comprising means for making magnetic pole centers of equal-polarity of said first and said second field magnets in phase by a direction of torque generated in said rotor and by balance of magnetic action forces between said first and said second field magnets;
• and means for making the magnetic pole centers of said first and said second field magnets out of phase when the direction of torque generated in the rotor is reversed.