METHOD OF CONTROLLING PREHEATING POWER AND MECHANISM FOR PROVIDING PREHEATING

摘要

The present invention relates to a motor and especially to a technique for maintaining constant power consumption in preheating a compressor motor in an air conditioner. An object thereof is to permit constant preheating of the motor irrespective of variations in receiving voltage. To accomplish this object, switching control of an inverter (15) that applies a three-phase current to a motor (30) is performed by a control circuit (20) in accordance with a duty based on detected values of voltage (Vm) and current (Im). This duty decreases with increasing receiving voltage.