Power delivery system for a tank load characterized by series-connected inverter bridges and a high voltage source

Claim 1

An electric power system for delivering alternating current to a tank load, comprising: a. a source of unipolarity voltage of relatively high magnitude; b. a current smoothing inductor; c. an inverter section having a pair of input terminals connected via said inductor to said source, a pair of output terminals connected to the tank load, and a plurality of current-source, load-commutated electric inverter bridges connected in series with each other across said input terminals, each of said bridges including: i. first and second alternately conducting thyristors, ii. a transformer having its own core and separate primary and secondary windings thereon, said secondary winding being connected between said output terminals, and iii. means for interconnecting said thyristors and said primary winding so that current from said source can flow through said primary winding in one direction when said first thyristor is conducting and in the opposite direction when said second thyristor is conducting; and d. control means independent of the transformers in said inverter bridges for running said inverter section at a desired frequency, said control means being operative periodically to trigger the first thyristors of all of said bridges simultaneously with one another and, alternately with the triggering of the first thyristors, to trigger the second thyristors of all of said bridges simultaneously with one another.