Frequency inverters, also known as frequency converters, are electronic devices that transform the voltage of the alternating sinusoidal network into direct voltage and in conclusion convert the latter into a voltage of variable amplitude and frequency.
The speed of rotation of an induction electric motor requires the frequency of the mains. If frequency is high, the rotation will increase and vice versa. Thus, when an induction motor is fed by a frequency inverter, the speed of the motor shaft can be easily adjusted by the frequency change imposed by the inverter.
The frequency of operation of an inverter is usually between 0.5 and 400Hz, depending on the model and the brand. Frequency inverters have an input connected to the common power supply network, which can be single-phase or three-phase, and an output that is used for the device to be supplied, in this case a three-phase induction motor (MIT).
Frequency inverters not only control the speed of the axis of AC motors, they also adjust other specific parameters of the electric motor, one of which is the torque adjustment.