Inverter-type power supply circuit for electrical machining

A power supply circuit for electrical machining, comprising:

• a plurality of inverter circuits connectable in parallel with one another to have their respective input sides connected jointly to a common source of commercial alternating current and their respective output sides connected jointly to a single electrical machining gap, each of said parallel inverter circuits individually comprising:
• a transformerless input means connectable directly to said common source of alternating current of a commercial supply frequency and an original voltage,
• a rectifier means connected to said input means directly for converting said commercial alternating current to a direct current at said original voltage, and
• a high-frequency transformer having a primary winding connected via a high-frequency switch means to the output of said rectifier means and a secondary winding connectable via further rectifier means to said single electrical machining gap;
• a common pulsing means for said plurality of the high-frequency switch means and for supplying thereto in unison a succession of signal pulses and thereby pulsing each of said direct currents at the respective outputs of said plural rectifier means to produce a succession of transformed alternating output pulses of a desired voltage level and with time parameters corresponding to said succession of signal pulses at each of said plural high-frequency transformers and, in turn, to provide at the respective outputs of said plural further rectifiers a concurrently occurring plurality of trains of unidirectional machining pulses with each machining pulse having said desired voltage level and with successive machining pulses corresponding in time parameters to successive signal pulses and eventually to superimpose said machining pulses at the outputs of said plural further rectifier means upon one another to provide a succession of superimposed machining pulses and for applying said succession of the superimposed machining pulses across said single electrical machining gap, at least two of said high-frequency transformers having different ratios of transforming said voltage to said desired voltage level so that said concurrently occurring machining pulses at the outputs of the respective further rectifiers connected to said at least two high-frequency transformers have different voltage levels to be superimposed upon one another to provide desired voltage and current characteristics of said superimposed machining pulses across said single electrical machining gap.