Frequency converters

A frequency converter or inverter or drive in the jargon for short is an electronic power circuit that is able to change the frequency of a supplied power supply while varying the voltage so that the torque is maintained.
Variable speed drives are usually used to control the speed of a three-phase asynchronous motor by changing the frequency of the rotating field. The controller can also be used as a starting device.
The principle is to adjust the frequency to control the speed:

Danfoss Inverters & Soft starters

Nastec Inverters

Mitsubishi Inverters

Omron Inverters

Siemens Soft-starters

Yaskawa Inverters