Frequency inverters control the speed of three-phase alternating current electric motors as well as control other parameters essential to the electric motor, one of which is torque control. This versatile and dynamic equipment is widely used in many different areas and equipment such as elevators, machine tools, pumps, mechanical traction. Frequency inverters are electronic devices that convert the voltage from the alternating sinusoidal network into direct voltage and finally convert the latter into a voltage of variable amplitude and frequency.
The speed of rotation of an induction motor depends on the frequency of the mains, as the higher the frequency, the greater the rotation and vice versa. Thus, when an induction motor is fed by a frequency inverter, it is possible to naturally control the speed of the motor shaft by means of the frequency variation imposed by the inverter. The frequency of operation of an inverter is usually between 0.5 and 400Hz, which will depend on the model and the brand. The frequency inverters have an input connected to the common power supply network, which may be single-phase or three-phase, and an output which is applied to the device to be fed, in this case a three-phase induction motor.