A system and method for controlling the output power of a heat source. The system includes a user interface so that a user may select the power required from the heat source, a power supply, and a controller that receives a rectified signal having a work ratio that corresponds to a nominal voltage of an alternating voltage signal corresponding to a phase of a power supply. The controller is configured to control the output power of the heat source in accordance with the power selected by the user, and modifies, if necessary, the work cycle of a power signal linked to the heat source in accordance with the work ratio in order to compensate possible differences in the nominal voltage between different power supplier.