Inductive heater for ferromagnetic material

摘要

The appts. incorporates a primary coil (20) which is supplied with variable frequency AC. The ferromagnetic body acts as the secondary coil (22). Signals from a temp. regulator (16) are fed to a temp. regulating circuit (14) connected to a reference value circuit (15). The output of the temp. regulator passes to a control circuit (11). The 3-phase power supply is connected to a DC + line and line by rectifier diodes (4,5), and the DC is smoothed by an LC circuit (6,7). There are two transistors (9,10) with their collector-emitter paths in series between the + and lines, and their bases connected to the control circuit (11). The mid-point between the transistor is converted to the primary coil, and there are diodes (17,18) in parallel with the transistors.