Welding device

A welding device comprising:

• a switching circuit having switching elements;
• a current detector and a voltage detector that detect a welding output;
• a controller programmed to calculate an output-on period of the switching circuit based on a setting output and the welding output;
• a frequency controller programmed to determine and change an inverter frequency based on the output-on period;
• and
• a driver controller programmed to control an on/off operation of the switching elements based on the inverter frequency and the output-on period,
• wherein the output-on period is a proportion of time of a duty cycle during which the welding output is on,
• when the duty cycle of the output-on period is a first ratio, the inverter frequency is determined and set, by the frequency controller, to a first frequency, and the switching elements are driven, by the driver controller, at the first frequency,
• when the duty cycle of the output-on period is a second ratio smaller than the first ratio, the inverter frequency is changed, by the frequency controller, to a second frequency higher than the first frequency, and the switching elements are driven, by the driver controller, at the second frequency, and
• when the duty cycle of the output-on period is a third ratio smaller than each of the first ratio and the second ratio, the inverter frequency is changed, by the frequency controller, to a third frequency higher than each of the first frequency and the second frequency, and the switching elements are driven, by the driver controller, at the third frequency.