Technology for Next-generation Reduced-size High-performance Inverter

INTRODUCTION IT is about 30 years since electric trains using VVVF (variable voltage variable frequency) inverter control first appeared in Japan. Since then, VVVF inverters for rolling stock (referred to below as “inverters”) have undergone a steady stream of improvements. The driving forces behind this development have been the high degree of safety and reliability demanded for social infrastructure and the pursuit of better economics through energy efficiency and low maintenance. On top of this, the growing concern about global environmental protection in recent years has added an extra impetus to the improvement of environmental performance. Against this background, Hitachi has developed an inverter that suits modern requirements. This article describes the next-generation reducedsize high-performance inverter developed by Hitachi (see Fig. 1).