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This is a VVVF inverter system using IGBT elements that are effective in achieving smaller size, lighter weight, less noise and high harmonic frequency reduction. It drives two three-phase induction motors, although four or eight motors are also possible depending on the capacity. The IGBT elements are installed inside the power unit, constituting a VVVF inverter system with the power unit and gate logic section.

Diagram of Circuit

System Unit list
Traction motorPhoto of Traction motorMaintenance involving dismantling of the main motor is simplified.
- Dirt ejection structure using pressure fan
- Long-life new grease
Main TransformerPhoto of Main Transformer Because of the small size and light weight, various measures have been taken including the use of heat-resistant insulating materials, iron core materials with advanced orientation properties (Hi-B materials). In order to contribute to reductions in noise and maintenance work, as shown in the photograph, the wind arising while the cars are in motion is used for cooling the main transformer.
IGBTPhoto of the IGBT This is a module-type IGBT that realizes the world’s maximum dielectric voltage of 3,300 V. As well as reducing the noise of the inverter system, it also enables smaller size, lighter weight and higher efficiency.
Power UnitDiagram of internal insulation
Photo of Power Unit
The constituent parts are arranged in the form of standard modules, thereby facilitating maintenance and enabling response to a wide variety of needs.

The size of the unit is minimized by means of insulation inside the IGBT units and the use of pure water for heat pipes. Attention has also been paid to environmental conservation.
Gate Logic UnitPhoto of Gate Logic Unit A 32-bit multi micro-computer system enables high-precision control, multi-functioning, and smaller size.
VVVF InverterPhoto of VVVF Inverter 
Filter ReactorPhoto of Filter Reactor A self-cooling system is used to do away with the need for maintenance and to reduce noise. Size has been reduced by integrating several coils.