High frequency inverter

An inverter for supplying high frequency alternating current to a load having resistance and inductance connected in parallel with capacitance means to form a tank circuit having an impedance which is subject to variations during operation, said inverter comprising a DC voltage source provided with a center tap, first and second sets of thyristors and capacitors, each of said sets having at least one pair of parallel branches with at least two series-connected thyristors in each branch and capacitance means connected between the midpoints of the branches of each said pair, the first said set being connected to the positive side of said voltage source, the second said set being connected to the negative side of said voltage source, one side of said load being connected to said center tap, a first inductance means connected in series between said first set and the other side of said load, a second inductance means connected in series between said second set and said other side of said load, said inductance means forming tuned circuits with said load and said capacitance means, a first diode means having its anode connected to the negative side of said voltage source and its cathode connected to the terminal of said first inductance means which is not connected to the load, a second diode means having its cathode connected to the positive side of said voltage source and its anode connected to the terminal of said second inductance means which is not connected to the load, and means for firing said thyristors in a predetermined sequence alternating between the first and second of said sets to cause an alternating current to flow in the load, the thyristors of each set being fired in pairs, each pair consisting of thyristors in different parallel branches of the set, the thyristors of each pair being in series relation with the capacitance means, and the pairs of each set being fired alternately, whereby the polarity of the voltage across the capacitance means within each said set reverses with each half-cycle of current delivered by said set.