Inverter control apparatus and inverter apparatus

An inverter control method applied to an inverter apparatus including an inverter which converts a DC voltage into an AC voltage and outputs the AC voltage to an AC motor, and a current sensor which measures a DC current on the input side of the inverter, the inverter control method comprising:

• a phase current calculation step of calculating each of phase currents flowing into the AC motor by using measurement results of the current sensor;
• a voltage command calculation step of calculating three-phase voltage commands supplied to the AC motor by using the phase currents calculated in the phase current calculation step;
• a command modulation step of mutually comparing the phase voltage commands generated in the voltage command calculation step, to specify a full-on phase or a full-off phase on the basis of a comparison result and then to set the voltage command of the specified phase to a full-on voltage corresponding to duty 100% or a full-off voltage corresponding to duty 0%, and offsetting the voltage commands of the other two phases according to the full-on voltage or the full-off voltage to modulate the voltage commands into voltage commands allowing the line voltage between the other two phases to be kept constant;
• a carrier wave generation step of generating a first carrier wave as a reference, a second carrier wave delayed from the first carrier wave by a fixed time, and a third carrier wave advanced from the first carrier wave by the fixed time;
• and
• a PWM signal generation step of generating PWM signals by comparing, according to a predetermined rule set in advance, each of the phase voltage commands modulated in the command modulation step with the three carrier waves generated in the carrier wave generation step.

An inverter control method applied to an inverter apparatus including an inverter which converts a DC voltage into an AC voltage and outputs the AC voltage to an AC motor, and a current sensor which measures a DC current on the input side of the inverter, the inverter control program making a computer execute:

• calculating each of the phase currents flowing into the AC motor by using measurement results of the current sensor;
• calculating three-phase voltage commands supplied to the AC motor by using the phase currents calculated in the phase current calculation process;
• mutually comparing the phase voltage commands generated in the voltage command calculation process, to specify a full-on phase or a full-off phase on the basis of a comparison result and then setting the voltage command of the specified phase to a full-on voltage corresponding to duty 100% or a full-off voltage corresponding to duty 0%, and offsetting the voltage commands of the other two phases according to the full-on voltage or the full-off voltage to modulate the voltage commands into voltage commands allowing the line voltage between the other two phases to be kept constant;
• generating a first carrier wave as a reference, a second carrier wave delayed from the first carrier wave by a fixed time, and a third carrier wave advanced from the first carrier wave by the fixed time;
• and
• generating PWM signals by comparing, according to a predetermined rule set in advance, each of the phase voltage commands modulated in the command modulation process with the three carrier waves generated in the carrier wave generation process.