St. Onge Steward Johnston & Reens, LLC
Resonant frequency induction furnace system using capacitive voltage division
 An induction furnace having a voltage source series inverter, a load circuit having a combination of an induction coil and a resonating capacitor bank, and control circuitry to phase lock the inverter frequency to the natural resonant frequency of the load. The capacitor bank can be divided into two groups, one across the output of the inverter and the other in series with the load. This arrangement allows for the division of the inverter voltage across the furnace coil according to the ratio of the two capacitances. The inverter uses pulse width modulation and is buffered from the load circuit by means of a small series connected inductor. Additionally, the system can have a common power supply system that supplies power in any desired proportion to a plurality of induction furnaces. 
ABB Metallurgy
Y H H
Y02B H05B H02M
additional inventional inventional
Jan Robert Daniel
Fablanowski Ibach Green