Power transforming apparatus and air conditioner including the same

An operating method of a power transforming apparatus for driving an inverter to drive a motor, the operating method comprising:

• detecting a magnitude of input power and a speed of the motor when the inverter is driven;
• based on the detected magnitude of input power and the speed of the motor, determining a number of target converter channels to perform a PFC operation among a plurality of converter channels;
• changing the target converter channels corresponding to the determined number of converter channels and controlling the PFC operation to be performed at a time satisfying a preset condition,
• based on the input power and the speed of the motor, determining whether to start the PFC operation, wherein the plurality of converter channels comprise a first converter channel, a second converter channel, and a third converter channel, wherein each converter channel is coupled to a reactor, and the reactor is disposed between a switching device of each converter channel and a diode;
• detecting a zero-crossing of a current flowing through a reactor in response to the PFC operation of a target converter channel corresponding to a predetermined sequence,
• based on the PFC operation being started, performing an initial switching operation with at least one converter channel selected using a random function;
• and
• based on the zero-crossing being detected, controlling a switching operation to be performed by changing a target converter channel according to a switching sequence determined based on the selected at least one converter channel.

An air conditioner comprising a compressor to which a power transforming apparatus is applied, wherein the power transforming apparatus comprises:

• a rectifier configured to rectify an input AC voltage;
• a power factor improving unit configured to perform a power factor correction (PFC) operation that improves a power factor on a rectified voltage output from the rectifier, the power factor improving unit comprising a plurality of converter channels;
• a DC link capacitor configured to store an output voltage of the power factor improving unit;
• a current sensor disposed between the rectifier and the power factor improving unit;
• and
• a controller configured to (i) based on an input power and a speed of a motor calculated using the current sensor when an inverter is driven, determine a number of target converter channels to perform a PFC operation among the plurality of converter channels, and (ii) perform the PFC operation while changing the target converter channels corresponding to the determined number of converter channels at a time satisfying a preset condition,
• wherein the power factor improving unit comprises a first converter channel, a second converter channel, and a third converter channel, wherein each converter channel is coupled to a reactor, and the reactor is disposed between a switching device of each converter channel and a diode,
• wherein the controller is configured to (i) based on the calculated input power and the speed of the motor, determine whether to start the PFC operation, and (ii) detect a zero-crossing of a current flowing through the reactor in response to the PFC operation of target converter channels corresponding to a predetermined sequence, and
• wherein the controller is configured to (i) based on the PFC operation being started, perform an initial switching operation with at least one converter channel selected using a random function, and (ii) based on the zero-crossing being detected, perform a switching operation by changing a target converter channel according to a switching sequence determined based on the selected at least one converter channel.