Abstract: The invention concerns the transformation of alternating or direct current input power to alternating current output power with intermediary transformation in direct current by means of static converters.According to the invention, an adapter placed in the direct current intermediary circuit (4) comprises a branch connected between the output terminals of the input converter (5), and contains in series a free wheel thyristor (18) and an inductance (16) whose value is equal to the total loss inductance of the motor (1) connected to the reversible output inverter (20).The purpose is to reduce the current wave harmonics in the power supply.

Abstract: An adjustable current input inverter-induction motor drive using a commutation bridge associated with a common commutating capacitor and four commutating thyristors. Capacitive means is provided for transferring energy during commutation from one main thyristor branch to the next in sequence through the inverter, and a capacitor inputting in a transformer and full wave rectifier bridge is provided coupled to said capacitive means for recuperating excess energy and for restitution thereof into the DC link of the inverter.