Heating power supply apparatus for polycrystalline semiconductor rods

A heating power supply apparatus for manufacturing polycrystalline semiconductor rods, comprising:

• a power transformer having a primary winding and a secondary winding, said secondary winding having plural portions;
• anti-parallel thyristor unit groups having input terminals connected to respective portions of the secondary winding of said power transformer and having commonly connectd output terminals;
• at least a first group of plural balance transformers having respective primary and secondary windings, said balance transformer primary windings connected to said anti-parallel thyristor group output terminals;
• semiconductor rod connecting terminals connected to respective of said rods and to the secondary windings of said first group of balance transformers;
• wherein the secondary winding of each balance transformer is connected in series with the primary winding of a different balance transformer and in series with respective of said semiconductor rod connecting terminals so that a constant secondary current flows in each of said balance transformer and in each of said semiconductor rods;
• feedback control means for detecting the secondary current in said secondary windings of said first group of balance transformers and for selecting at least one of said anti-parallel thyristor unit groups to drive said first group of balance transformers such that said secondary current is maintained within a predetermined range during manufacture of said rods to a predetermined size.