Electric Motor Frequency Converters

A frequency converter is a power electronics device, which is used in adjusting the rotation speed of an alternating current (AC) motor, such as the short circuit motor. The frequency converter increases the rotation speed of a controlled motor above the normal frequency of an electric motor. The frequency converter is equipped with two converters, a rectifier and an inverter, between which is provided a direct voltage or a direct current intermediate circuit.   

Frequency converters for electric motors include two types of configurations, including the pulse-width-modulated frequency converter (PWM frequency converter) and the pulse-amplitude-modulated frequency converter (PAM frequency converter). Both not only change the frequency of the voltage lying at the motor but also the voltage itself to control the rotational speed of the motor with low losses and to be able to operate the motor with an essentially constant torque.