Abstract: A first condenser is connected between output terminals of a rectifier circuit which receives an AC power as an input, and a three phase inverter is connected in parallel with respect to the first condenser, and output of the three phase inverter is supplied to a motor, and a second condenser is connected in parallel to the input side of the three phase inverter, and a current detector is connected between the first condenser and the second condenser, and a third condenser is connected in parallel to the first condenser at a position slightly power side with respect to the current detector, and the capacitance of the second condenser is determined as small as possible within the range in which power devices are not destroyed by surge voltage due to switching, therefore, ringing is suppressed, and taking of current is performed rapidly and with high accuracy.

Abstract: The phase current detection apparatus comprises an output time detection section 6a for receiving a voltage vector command as input, and for detecting a voltage vector which should be enlarged its output time, output time enlargement section 6bfor receiving the voltage vector command and the voltage vector detected by the output time detection section 6a as input, and for carrying out enlargement processing for output time (enlarge the output time up to a length allowing the current detector 5 to detect the voltage vector), subtraction section 6c for subtracting the length of actually output voltage vector from the voltage vector command, and for outputting an error, output error integrating section 6d for integrating the error from the subtraction section 6g and for calculating an integrated error of an output with respect to the voltage vector command, reverse vector generation section 6e for outputting a vector (reverse vector) which is obtained by replacing the ON/OFF in Table 1 for the enlarged voltage v

Abstract: A first condenser (2a) is connected between output terminals of a rectifier circuit (2) which receives an AC power (1) as an input, and a three phase inverter (3) is connected in parallel with respect to the first condenser (2a), and output of the three phase inverter (3) is supplied to a motor (4), and a second condenser (3a) is connected in parallel to the input side of the three phase inverter (3), and a current detector (5) is connected between the first condenser (2a) and the second condenser (3a), and a third condenser is connected in parallel to the first condenser (2a) at a position slightly power side with respect to the current detector (5), and the capacitance of the second condenser (3a) is determined as small as possible within the range in which power devices are not destroyed by surge voltage due to switching, therefore, ringing is suppressed, and taking of current is performed rapidly and with high accuracy.

Abstract: 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.

Abstract: 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.