9000 kW-1500Hz Frequency Converter for Hot Bar Heater

Abstract

In the field of a hot strip mill facility of steel industry, there are needs of large power induction-heating equipment for energy saving and improvement of a product quality. We have delivered the 9,000 kW-1,500 Hz frequency converters for induction-heater, the largest in the world. We applied the series connection technology and the parallel connection technology of the thyristor to realize a high-power and high-frequency inverter. The analog-digital hybrid control has been developed to respond the flexible and fast acting control. The developed converter has been delivered to several factories and continues to operate. And more very large inverters up to around 23000 kW have been also realized by paralleling the 9000 kW converters.