To solve the difficulty of medium voltage variable frequency drive of fan or pump, a technique, rotor-side variable frequency drive (RVFD), is introduced that a less power (0.2-0.3P/sub N/) low voltage (<400 V) IGBT converter is used to adjust speed of a full power medium voltage (6-10 kV) motor. The features of the technique are: simple circuit, less large devices, better power factor and smaller harmonics. An improved RVFD based on PFC technique is proposed, it can remove the influence caused by diode rectifier.

Xiaoliang Ma

Papers

Use a less power low voltage IGBT converter to adjust speed of a full power medium voltage induction motor of fan or pump