Frenic 4600 is a series of environment friendly medium voltage IGBT inverters. It raises the efficiency and power factor of medium voltage motors by stabilizing motor operations and conserving energy. The multi-phase diode rectifier system reduces harmonics on the power source side. Fuji Electric’s unique multi-level PWM control system reduces the switching surge and even standard motors can be operated. It provides a high-power factor (95% or more) on the power source. Output transformers can be eliminated and that improves total efficiency (approx 97%). High reliability is achieved by reducing the number of inverter cells and using a single-phase, 3-level inverter. Sensorless vector control functions ensure stable operations despite load fluctuations. The control device has a 32-bit MPU for quick response and high accuracy