Voltage converter

A voltage conversion circuit for conversion of an input d.c. voltage (UE) into a three-phase a.c. current (UR, US, UT) in a mains frequency range having at least one inductor (L1, L2) and several switches (S1, . . . , S9) controlled by a drive circuit (AST), comprising:

• a first converter section for producing positive output voltage portions and a second converter section for producing negative output voltage portions, and
• output of the first converter section via one of a plurality of first longitudinal phase circuit breakers (S4, S5, S6) and output of the second converter section via one of a plurality of second longitudinal phase circuit breakers (S7, S8, S9) are connected to produce three-phase current outputs (R, S, T), wherein:
• a ground pole (m) of the d.c. voltage (UE) is directly connected to a PEN conductor (N) of the three-phase outputs,
• a first series connection of a first transverse switch (S3) and a transverse inductor (L2) is between a non-ground pole (p) of the d.c. voltage and ground,
• a junction point of the first series connection (S3, L2) is connected via one of the second longitudinal phase circuit breakers (S7, S8, S9) to the three-phase outputs (R, S, T),
• the non-ground pole (p) of the d.c. voltage is also connected in a second series connection via a longitudinal circuit breaker (S1) and in series with it a longitudinal inductor (L1) via one of the first longitudinal phase circuit breakers (S4, S5, S6) so the three-phase outputs (R, S, T) and via a second transverse switch (S2) to ground, and a junction point of the second series connection of the longitudinal circuit breaker (S1) with the longitudinal inductor (L1) is connected to ground via a diode (D1) that is in the blocking direction in relation to the input voltage,
• the longitudinal inductor (L1) together with the longitudinal circuit breaker (S1) and the second transverse switch (S2) and one of the first longitudinal phase circuit breakers (S4, S5, S6) and diode (D1) defining a step-up/step-down converter forming the first converter section (S1, D1, L1, S2), and the second transverse inductor (L2) together with the first transverse switch (S3) and one of the second longitudinal phase circuit breakers (S7, S8, S9) defining an inverting converter forming the second converter section (S3, L2).