Patent AT-E400924-T1: [Translated] METHOD FOR DYNAMIC SYMMETIZATION OF SERIES AND PARALLEL-CONNECTED POWER SEMICONDUCTOR SWITCHES

A method for dynamically balancing the loads in a circuit ( 1, 4 ) of semiconductor power switches arranged in series or in parallel is disclosed. Individual switching signals (i<SUB>G1</SUB>, i<SUB>G2</SUB>) for the semiconductor power switches (S<SUB>1 </SUB>. . . S<SUB>4</SUB>) are generated by determining a system-widely valid synchronous sampling time (ts<SUB>j</SUB>) independently for each semiconductor power switch (S<SUB>1 </SUB>. . . S<SUB>4</SUB>) due to a synchronous event (es) of the whole circuit ( 1, 4 ). Control loop offsets between actual values (a<SUB>i</SUB>) measured synchronously at the sampling time (ts<SUB>j</SUB>) and given desired values (a<SUB>s</SUB>) of an asynchronous state variable (a(t)) of the semiconductor power switches (S<SUB>1 </SUB>. . . S<SUB>4</SUB>) are reduced in the same or in following switching cycles. Alternatively, control loop offsets between actual time values (ta<SUB>i</SUB>) and desired time values (ta<SUB>s</SUB>) are minimized, wherein the actual time values (ta<SUB>i</SUB>) are measured upon exceeding a globally provided threshold value (epsilon<SUB>a</SUB>) of an asynchronous state variable (a(t)) of the semiconductor power switches (S<SUB>1 </SUB>. . . S<SUB>4</SUB>). Embodiments relate to: Offsetting the sampling time (ts<SUB>j</SUB>) in time by a globally provided time interval (Deltat 0 ), providing desired values locally or globally, e.g. by averaging of actual values (a<SUB>i</SUB>, ta<SUB>i</SUB>), additional balancing of the gradients of asynchronous time variables (a(t)). A central sampling command can be dispensed with and the switching synchronicity is improved, switching times are shortened and dynamic switching losses are reduced.