Inverter controller for driving motor and air conditioner using inverter controller

An air conditioner which includes a converter apparatus for converting AC power to DC power and an inverter apparatus for converting the DC power converted by the converter to AC power of a variable voltage and a variable frequency and supplying the AC power to a motor for driving a compressor,

• wherein the inverter apparatus comprises:
• an AC power supply for supplying an AC power;
• a rectifier formed of a diode bridge for rectifying the AC power to be converted to DC power;
• a reactor having a predetermined small capacity which is connected to the rectifier, for improving a power factor of the AC power supply;
• an inverter which converts the DC power to AC power for driving the motor;
• a capacitor having a predetermined small capacity which is connected between DC bus lines of the inverter to absorb regeneration energy from the motor;
• a motor voltage command generator which generates a motor voltage command value of the motor, based on a speed command value of the motor applied from the outside;
• a positive neutral (PN) voltage detector which detects a DC voltage value of the inverter;
• a PN voltage corrector which calculates a ratio of the DC voltage detection value of the inverter obtained by the PN voltage detector to a predetermined DC voltage reference value of the inverter to thereby generate a PN voltage correction factor;
• a first motor voltage command corrector which performs voltage correction of the motor voltage command value by multiplying the motor voltage command value obtained by the motor voltage command generator by the PN voltage correction factor which is an output value of the PN voltage corrector to thereby produce a motor voltage command correction value;
• a motor current detector which detects a motor current of the motor;
• a beat amount corrector which calculates a fluctuation amount of the motor current from the motor current detection value obtained by the motor current detector and generates a reverse phase component of the motor current fluctuation amount;
• and
• a second motor voltage command corrector which performs voltage correction of the motor voltage command correction value by multiplying the motor voltage command correction value obtained by the first motor voltage command corrector, by an output value of the beat amount corrector, and generates a voltage command value to be applied to the motor.