Method for operating a power converter, and power converter control unit

1. A method for operating a power converter including at least one power converter half-bridge, in which controllable switching elements and freewheeling diodes connected parallel thereto and in a blocking direction are provided respectively between a first direct voltage terminal and an alternating voltage terminal, as well as between the alternating voltage terminal and a second direct voltage terminal, the method comprising:

controlling the switching elements of the at least one half-bridge in alternating fashion and in each case interrupted by controlling pauses; and

setting a duration of the controlling pauses on the basis of a determined voltage drop at at least one of the freewheeling diodes;

wherein the method further comprises determining the voltage drop at the at least one of the freewheeling diodes, and wherein the duration of the controlling pauses is set based on the determined voltage drop exceeding a threshold value.

2. The method as recited in claim 1 , further comprising:

operating the power converter in an inversion operating mode, in which a direct voltage present at the first and second direct voltage terminals is converted into an alternating voltage.

3. The method as recited in claim 2 , further comprising:

applying the alternating voltage to an inductive load.

4. The method as recited in claim 3 , wherein the inductive load includes a stator winding of an electric machine.

5. The method as recited in claim 1 , further comprising:

determining the voltage drop at the at least one freewheeling diode by a comparator.

6. The method as recited in claim 5 , wherein the comparator has hysteresis.

7. The method as recited in claim 1 , wherein the duration of the controlling pauses is set in that when none of the switching elements is controlled, a waiting first takes place until a voltage drop is determined at the at least one freewheeling diode, and only then is a control signal outputted to one of the switching elements.

8. The method as recited in claim 1 , wherein the duration of the controlling pauses is additionally set on the basis of at least one of a predetermined time period and a calculated time period.

9. The method as recited in claim 1 , further comprising:

determining a direction of a current at the alternating voltage terminal by determining at which of the freewheeling diodes a voltage is dropped.

10. A power converter control unit for controlling a plurality of controllable switching elements in at least one power converter half-bridge of a power converter using control signals, and for setting controlling pauses between the control signals, the power converter control unit comprising:

an arrangement for controlling the switching elements of the at least one half-bridge in alternating fashion and in each case interrupted by the controlling pauses; and

an arrangement for setting a duration of the controlling pauses on the basis of a determined voltage drop at at least one freewheeling diode;

wherein the method further comprises determining the voltage drop at the at least one of the freewheeling diodes, and wherein the duration of the controlling pauses is set based on the determined voltage drop exceeding a threshold value.

11. A power converter system comprising:

a power converter including at least one power converter half-bridge in which controllable switching elements and freewheeling diodes connected parallel thereto and in a blocking direction are provided respectively between a first direct voltage terminal and an alternating voltage terminal, as well as between the alternating voltage terminal and a second direct voltage terminal; and

a power converter control unit including:

an arrangement for controlling the switching elements of the at least one half-bridge in alternating fashion and in each case interrupted by controlling pauses, and

an arrangement for setting a duration of the controlling pauses on the basis of a determined voltage drop at at least one of the freewheeling diodes;

wherein the method further comprises determining the voltage drop at the at least one of the freewheeling diodes, and wherein the duration of the controlling pauses is set based on the determined voltage drop exceeding a threshold value.

12. The power converter system as recited in claim 11 , wherein at least one of the controllable switching elements, together with the freewheeling diodes connected in parallel, includes a MOSFET.

13. A motor vehicle generator, comprising:

an electric machine; and

a power converter system connected to the electric machine, the power converter system including:

a power converter including at least one power converter half-bridge in which controllable switching elements and freewheeling diodes connected parallel thereto and in a blocking direction are provided respectively between a first direct voltage terminal and an alternating voltage terminal, as well as between the alternating voltage terminal and a second direct voltage terminal, and

a power converter control unit including:

an arrangement for controlling the switching elements of the at least one half-bridge in alternating fashion and in each case interrupted by controlling pauses, and

an arrangement for setting a duration of the controlling pauses on the basis of a determined voltage drop at at least one of the freewheeling diodes;

wherein the method further comprises determining the voltage drop at the at least one of the freewheeling diodes, and wherein the duration of the controlling pauses is set based on the determined voltage drop exceeding a threshold value.

14. A non-transitory machine-readable storage medium having a computer program stored thereon that has a program code that causes a power converter control unit to carry out a method for operating a power converter including at least one power converter half-bridge, in which controllable switching elements and freewheeling diodes connected parallel thereto and in a blocking direction are provided respectively between a first direct voltage terminal and an alternating voltage terminal, as well as between the alternating voltage terminal and a second direct voltage terminal, the method comprising:

controlling the switching elements of the at least one half-bridge in alternating fashion and in each case interrupted by controlling pauses; and

setting a duration of the controlling pauses on the basis of a determined voltage drop at at least one of the freewheeling diodes;

wherein the method further comprises determining the voltage drop at the at least one of the freewheeling diodes, and wherein the duration of the controlling pauses is set based on the determined voltage drop exceeding a threshold value.