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

Using three-level pulse-width modulation (PWM) control with output voltage at 800 V AC, a single unit rated capacity of 1200 kVA is achieved and a drastic reduction in the output current harmonics. An Insulated Gate Bipolar Transistor (IGBT) device configuration ensures faster control response, lower power loss and a simplified inverter control circuit. It allows precision control ranging from + or -0.01% to a torque control of + or -5%. Weak field control that constantly monitors magnetic flux makes it possible to ensure smooth high-speed operations. In addition, optional features such as observer control (impact drop compensation, shaft torsional vibration suppression), speed control autotuning, and plant control software (mechanical loss setting, torque forcing fixed position stop control) are available to be built in.

In addition, by multiplexing the inverters, up to 3600 kVA (600 kVA x 6 inverter units) can be supported. There is no need for separate cooling fans in each unit and one cooling fan for the control panel is enough. High-efficiency plant operations can be achieved by exchanging power energy and regenerative energy with the DC distribution system over a common DC bus. While the control unit is in operation or stopped it is possible to check various data and status conditions, which makes it extremely easy to review the system operating state including safeguard and abnormal conditions with traceback functions available as an option.