Patent ID: 8138711

Claim:
A motor controller for an air conditioner, comprising: a converter adapted to convert AC power into DC power; an inverter having a plurality of switching elements and adapted to receive the DC power, convert the received DC power into AC power by switching operations of the switching elements, and supply the AC power to a motor; a current detector adapted to detect a current flowing in the motor controller; a temperature detector adapted to detect a temperature in the motor controller or a temperature ambient to the motor controller; and a controller adapted to: calculate a loading based on at least one of room temperature, setup temperature, and inner unit capacity, and set a final target frequency at which to drive the motor based on the calculated loading and at least one of the detected current and the detected temperature, and wherein the controller comprises: a first target frequency setup unit adapted to set up a first target frequency based on the calculated loading; a second target frequency setup unit adapted to set up a second target frequency based on at least one of the detected current and the detected temperature; and a final target frequency setup unit adapted to set up the final target frequency, wherein the final target frequency is a lower one of the first target frequency and the second target frequency.