Power converter with improved control of its main switches, and application to a power converter having three or more voltage levels

A power converter comprising at least one arm including, between a positive rail and a negative rail:

• two main switches enabling an outlet leading to a load to be connected either to the positive rail or the negative rail;
• two free-wheel diodes enabling the current through the load to be maintained by coupling the outlet respectively to the positive rail or to the negative rail;
• two snubber capacitors between the outlet and, respectively, the positive rail, and the negative rail;
• and
• an auxiliary circuit comprising, in particular, an auxiliary inductor in series with two oppositely-directed one-way auxiliary switches coupled between the outlet and a midpoint of a capacitive voltage divider itself comprising two voltage-dividing capacitors connected in series between the positive rail and the negative rail, and delivering at said midpoint, a voltage that is nominally a midpoint voltage compared with the voltages of the positive rail and of the negative rail;
• the converter further comprising a detector for detecting current oscillation between said auxiliary inductor and said snubber capacitors in a switchover process intended for causing a corresponding main switch to be switched on, said detector detecting an interruption of said oscillation current after said auxiliary circuit is switched on, and causing said corresponding main switch to be rendered conductive in response to said interruption.