The KEB COMBIVERT is a frequency inverter with DC-voltage link. The unit is exclusively designed as stepless speed control of three-phase AC motors. Its functionality is based on PWM (pulse-width modulation).

The internal circuit of a frequency inverter contains basically only three stages:

•  a mains rectifier;
• the DC-link;
• an inverter at the output.

The mains rectifier takes the single or three-phase main power supply and via a rectifying bridge converts the AC-voltage into a DC-voltage.