Practical tests on a novel series-connected CSI prototype for controlled induction heating application

Induction heating is commonly used in the industry for the metal heating, melting, hardening etc. The power converter used is a current source inverter (CSI). High power medium frequency application like melting use thyristor based CSIs, while in medium power and high frequency induction heating application (like surface heat treatment) IGBT based CSIs are increasingly preferred. In this paper simulated and experimental performance of an SCR-based CSI and IGBT based CSI in series cascade (with common dc-link) have been presented. Two laboratory prototypes of rating 2kW, 10kHz each have been fabricated and tested, both individually and then in series cascade. Cascade mode operation of CSIs may find important application in multi-stage surface heat treatment of metals.