Self-commutating inverter with controlled main valves in a center-tap circuit

Claim 1

In a self commutating inverter circuit comprising, an output transformer, the primary windings of which have a center tap connected to the positive terminal of a source of d-c voltage, the output windings of which are connected to a variable load, two main valves, the anode of each one connected respectively to the ends of said primary winding, the cathode of each connected to the negative terminal of said source of d-c voltage through a series choke inductor, two recovery diodes, the cathode of each one connected respectively to taps on either side of said center tap between said center tap and said ends of said primary winding, the anode of each one connected to said negative terminal of said source of d-c voltage, a series connected commutation capacitor and bidirectional electronic switching member, having a control electrode connected between the anodes of said main valves, and means for generating firing impulses for said main valves, the improvement comprising: first and second potential separating transformers each having a primary winding and a secondary winding, the primaries of said first and second transformers coupled respectively to the outputs of said means generating firing impulses for said two main valves; differentiating means having its output coupled to said control electrode of said bidirectional electronic switching means, an OR gate made up of two blocking diode having its two inputs coupled respectively to the secondaries of said first and second transformers and its output coupled as an input to said differentiating means.