Desenvolvimento e análise experimental de um regulador de tensão para o gerador de indução trifásico conectado na forma bifásica

Abstract

This work presents the design and implementation of a digital voltage regulator for a threephase induction generator that is self-excited and connected in a two-phase arrangement using the Fukami configuration. In this configuration, the three-phase induction machine is excited by two capacitors connected between two phases, creating a central point where another capacitor is connected to the remaining phase and to the load, thus forming a two-phase configuration. This allows the induction generator to be used in isolated and portable applications, which is mainly possible due to the fact that the induction machine is more robust and more affordable than the synchronous machine currently used for this purpose. However, the operation of this type of machine as a generator is not able to keep the terminal voltage stable under a load change, since it depends on the reactive power balance of the system. To overcome this problem, a regulator based on the ESP32 microcontroller was proposed, containing a PI (Proportional-Integral) controller developed digitally in the C language. The generator voltage is monitored by a voltage acquisition system at the load, which provides the ESP32 analog-to-digital converter with a DC voltage level proportionally close to the RMS value of the generated voltage. As the actuating element, a configuration with a bidirectional power switch was used, controlled by a PWM signal generated by the ESP32 control circuit. Thus, according to the load variation in the generator, the PI controller continuously adjusts the duty cycle in order to keep the terminal voltage at the desired value of 220 V at the load, acting as a voltage step-down stage.