Patent ID: 8069685

Claim:
An air conditioning system provided with a plurality of compressors, a condenser, a four-way valve, and a plurality of heat exchangers, wherein at least one of the plurality of compressors is a capacity modulation compressor comprising: an electromotive driving unit including a stator having a coil winding portion to which power is supplied, and a rotor that has conductive bars, flux barriers, and permanent magnets inserted in the flux barriers, wherein the rotor rotates due to interactive electromagnetic forces, wherein an induction torque is generated between the conductive bars and the coil winding portion of the stator, wherein a reluctance torque is generated between the flux barriers and the coil winding portion of the stator and wherein a magnetic torque is generated between the permanent magnets and the coil winding portion of the stator, and the rotor has different load torques assigned in a startup operation and in a normal operation, and wherein a capacitor is electrically connected to the coil winding portion of the stator; and a plurality of compression units capable of selectively compressing a working fluid so that the compressing capacity of the plurality of compression units may be varied; and wherein the air conditioning system includes a controller for controlling operation of the plurality of heat exchangers, and for controlling operation of the plurality of compressors and a compressing capacity of the capacity modulation compressor according to a change in a required cooling capacity for the plurality of heat exchangers, so as to modulate a total capacity of the plurality of compressors in multiple steps.