METHOD AND DEVICE FOR CONTROLLING POWER SEMICONDUCTOR SWITCHES CONNECTED IN PARALLEL

Abstract

The invention relates to a method (200) and a control device (1) for controlling at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel for switching a total current (I_ges). The at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel each have a gate terminal for controlling the respective power semiconductor switch (LHS1 . . . LHS2). An input terminal (EA) for feeding the total current (I_ges), an output terminal (AA) for discharging the total current (I_ges) and a joint control terminal (S) for receiving a joint control signal (SI) that has the state ‘disconnect’ or ‘connect’ are provided. The at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel are connected to the input terminal (EA) at the input end and to the output terminal (AA) at the output end. At least one ascertainment unit (EE) is designed to receive the joint control signal (SI) at the input end, ascertain at least two individual control signals (SI1 . . . SIn) in accordance with the joint control signal (SI) in order to control the at least two power semiconductor switches (LHS1 . . . LHSn), and output the at least two ascertained individual control signals to the gate terminals of the at least two power semiconductor switches at the output end. The at least two individual control signals (SI1 . . . SIn) each have the state ‘disconnect’ or ‘connect’ and differ at least temporarily.

Claims

1. A method (200) for controlling at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel for switching a total current (I_tot), wherein the at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel each have a gate terminal for controlling the respective power semiconductor switch (LHS1 . . . LHSn), the method comprising: providing an input terminal (EA) for feeding the total current (I_tot), an output terminal (AA) for conducting away the total current (I_tot) and a common control terminal (S) for receiving a common control signal (SI) having the states open or close, wherein the at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel are connected to the input terminal (EA) on the input side and to the output terminal (AA) on the output side; providing at least one ascertaining unit (EE) configured to receive the common control signal (SI) on the input side and to ascertain at least two individual control signals (SI1 . . . SIn) depending on the common control signal (SI) for controlling the at least two power semiconductor switches (LHS1 . . . LHSn) and, on the output side, to output the at least two individual control signals ascertained to the respective gate terminals of the at least two power semiconductor switches, wherein the at least two individual control signals (SI1 . . . SIn) each have the states open or close and the at least two individual control signals (SI1 . . . SIn) differ at least at times.

2. The method as claimed in claim 1, wherein the at least two individual control signals (SI1 . . . SIn) have the state open or close for different lengths of time.

3. The method as claimed in claim 1, wherein the at least two individual control signals (SI1 . . . SIn) have the same state open or close at least at times.

4. The method as claimed in claim 1, wherein ascertaining the individual control signals (SI1 . . . SIn) is carried out depending on the control signal (SI) in such a way that with the change in the control signal (SI) from the state open to the state close at least one first of the individual control signals (SI1 . . . SIn) maintains the state open and has the state close only after a first predefinable time (Ta) has elapsed, and that with the change in the control signal (SI) from the state open to the state close, at least one second of the individual control signals (SI1 . . . SIn) has the state close.

5. The method as claimed in claim 4, wherein ascertaining the individual control signals (SI1 . . . SIn) is carried out depending on the control signal (SI) in such a way that with the change in the control signal (SI) from the state close to the state open, the at least first individual control signal (SI1 . . . SIn) maintains the state close and has the state open only after a second predefinable time (Tb) has elapsed, and that with the change in the control signal (SI) from the state close to the state open, the at least second individual control signal (SI1 . . . SIn) has the state open.

6. The method as claimed in claim 4, wherein ascertaining the individual control signals (SI1 . . . SIn) is carried out depending on the control signal (SI) in such a way that with the change in the control signal (SI) from the state close to the state open, the at least second individual control signal (SI1 . . . SIn) maintains the state close and has the state open only after a third predefinable time (Tc) has elapsed, and that with the change in the control signal (SI) from the state close to the state open, the at least first individual control signal (SI1 . . . SIn) has the state open.

7. The method as claimed in claim 5, wherein the first and second predefined times (Ta, Tb) or the first and third predefined times (Ta, Tc) are of the same length.

8. The method as claimed in claim 1, wherein ascertaining the individual control signals (SI1 . . . SIn) is carried out depending on the control signal (SI) in such a way that in the case of successive states close of the control signal (SI), alternately different individual control signals (SI1 . . . SIn) have the states open in an alternating manner.

9. The method as claimed in claim 1, wherein the loading of the power semiconductor switches (LHS1 . . . LHSn) is determined and ascertaining an individual control signal (SI1 . . . SIn) is carried out depending on the respective loading of the power semiconductor switch (LHS1 . . . LHSn) to be controlled.

10. The method as claimed in claim 7, wherein an individual control signal (SI1 . . . SIn) has the state close if it controls a power semiconductor switch (LHS1 . . . LHSn) whose loading is lower than a predefinable loading threshold value.

11. The method as claimed in claim 8, wherein in order to determine a loading of a power semiconductor switch (LHS1 . . . LHSn), the temperature thereof, the power loss thereof, the transmitted quantity of energy thereof or the switching frequency thereof is taken into account.

12. The method as claimed in claim 1, wherein the functionality of the power semiconductor switches (LHS1 . . . LHSn) is determined and an individual control signal (SI1 . . . SIn) has the state close if it controls a functional power semiconductor switch (LHS1 . . . LHSn).

13. The method as claimed in claim 1, wherein at least partly parallel-connected power semiconductor modules are used as power semiconductor switches (LHS1 . . . LHSn) connected in parallel, wherein a power semiconductor module comprises power semiconductor switches (LHS1 . . . LHSn) connected in parallel.

14. A control device (1) for controlling at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel for switching a total current (I_tot), wherein the at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel each have a gate terminal for controlling the respective power semiconductor switch (LHS1 . . . LHSn), and the total current (I_tot) is fed via an input terminal (EA) and is conducted away via an output terminal (AA), and the at least two power semiconductor switches (LHS1 . . . LHSn) connected in parallel are connected to the input terminal (EA) on the input side and to the output terminal (AA) on the output side; comprising a common control terminal (S) for receiving a common control signal (SI) having the states open or close, and at least one ascertaining unit (EE) configured to receive the common control signal (SI) and to ascertain at least two individual control signals (SI1 . . . SIn) depending on the common control signal (SI) for controlling the at least two power semiconductor switches (LHS1 . . . LHSn) and, on the output side, to output the at least two individual control signals ascertained to the respective gate terminals of the at least two power semiconductor switches, wherein the at least two individual control signals (SI1 . . . SIn) each have the states open or close and the at least two individual control signals (SI1 . . . SIn) differ at least at times.

15. An electrical system (10), comprising a control device (1) as claimed in claim 14 and power semiconductor switches (LHS1 . . . LHSn) connected in parallel for switching a total current (I_tot) within a vehicle.

16. A computer program designed to perform all the steps of one of the methods as claimed in claim 1.

17. An electronic storage medium on which the computer program as claimed in claim 16 is stored.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The invention will be explained in greater detail below with reference to some figures; for this purpose, in the figures:

[0055] FIG. 1 shows an electrical system comprising a control device in a schematic illustration.

[0056] FIG. 2 shows an illustration of the control signals against time.

[0057] FIG. 3 shows a flow diagram for a method for controlling power semiconductor switches connected in parallel for switching a total current.

DETAILED DESCRIPTION

[0058] FIG. 1 shows an electrical system 10 in a schematic illustration. A total current I_tot is fed to the electrical system 10 at an input terminal EA. Power semiconductor switches LHS1 . . . LHSn connected in parallel are connected to the input terminal EA on the input side and to the output terminal AA on the output side. The total current I_tot is divided among the power semiconductor switches which are closed, that is to say have the state close. Accordingly, the sum of the individual currents I1 . . . In through the respective power semiconductor LHS1 . . . LHSn connected in parallel always corresponds to the total current I_tot. The total current I_tot is conducted away via the output terminal AA. The power semiconductor switches LHS1 . . . LHSn connected in parallel serve both for current carrying and interruption of the current flow from the input terminal EA to the output terminal AA. The power semiconductor switches LHS1 . . . LHSn connected in parallel each have a gate terminal. The gate terminals among one another are separated from one another, in particular. By way of example, the drawing illustrates that each individual power semiconductor switch has an individual gate terminal. Furthermore, the electrical system 10 comprises a control device 1 having a common control terminal S for receiving a common control signal SI. The control device comprises an ascertaining unit EE, to which the control signal SI is fed. The control signal has the states open or close. The ascertaining unit EE ascertains individual control signals SI1 . . . SIn depending on the control signal SI. The individual control signals (SIL.SIn) each have the states open or close. The individual control signals SI1 . . . SIn are output by the ascertaining unit EE and transmitted to the gate terminals for controlling the power semiconductor switches. This advantageously makes it possible to transmit the common control signal SI over a plurality of mutually independent single individual control signals SI1 . . . SIn. In this regard, for the current carrying of the total current I_tot from the input terminal EA to the output terminal AA, in a targeted manner individual or a subset of the power semiconductor switches LHS1 . . . LHSn connected in parallel can be controlled and used for the current carrying by means of the individual control signals SI1 . . . SIn. The same correspondingly holds true in particular also for the use of power semiconductor modules connected in parallel instead of the power semiconductor switches LHS1 . . . LHSn connected in parallel.

[0059] FIG. 2 shows various control signals plotted against the time axis t. The topmost line reveals the, for example clocked, common control signal SI, which has the state close in each case between the points in time T0 and T1, and T2 and T3 and otherwise has the state open. Depending on the control signal SI, the ascertaining unit EE ascertains individual control signals SI1 . . . SIn. By means of the electrical system 10, at the points in time at which the control signal SI has the state close, the total current I_tot is intended to be passed from the input terminal to the output terminal. FIG. 2 furthermore illustrates by way of example the individual control signals SI1 . . . SIn for overlapping operation of the power semiconductor switches LHS1 . . . LHSn. In this regard, during the first state close of the control signal SI, the individual control signal SI1 likewise has the state close. Consequently, the power semiconductor switch LHS1 is controlled for transmitting the total current. At the point in time T0, the individual control signal SI2 initially maintains the state open. After the first predefined time Ta has elapsed, the individual control signal SI2 also has the state close. The individual control signal SI2 furthermore has the state close until after the point in time T1, at which the state of the control signal SI changes from close to open, and after the subsequent second predefined time Tb has elapsed. In this example, the power semiconductor switch LHS1 accepts the switch-on and current-conducting losses during the first predefined time Ta and the power semiconductor switch LHS2 accepts the switch-off and current-conducting losses during the second predefined time Tb.

[0060] Upon the subsequent change in the state of the control signal SI from open to close at the point in time T2, a further power semiconductor switch LHS3 is controlled by means of the individual control signal SI3 with the state close. The power semiconductor switch LHS3 is controlled for transmitting the total current. The individual control signal SIn initially maintains the state open. After a time has elapsed after the point in time T2, in this example once again having the duration of the first predefined time Ta, the individual control signal SIn has the state close. After the point in time T3, at which the state of the control signal SI changes from close to open, the individual control signal SIn has the state open. The individual control signal SI3 furthermore has the state close until after the point in time T3 and the subsequent third predefined time Tc has elapsed. In this example, the power semiconductor switch LHS3 accepts both the switch-on and current-conducting losses during the predefined time Ta and the switch-off and current-conducting losses during the third predefined time Tc. Since, in this example, the switch-on and current-conducting losses during the first predefined time Ta and also the switch-off and current-conducting losses during the third predefined time Tc are distributed over the power semiconductor switch(es) LHS3 controlled with the individual control signal SI3, these power semiconductor switches in this example are loaded to a greater extent than the power semiconductor switches LHSn controlled with the individual control signal SIn. Depending on the choice or ascertainment of the individual control signals, the loading can be distributed among the power semiconductor switches LHS1 . . . LHSn in a targeted manner.

[0061] FIG. 3 shows a method 200 for controlling power semiconductor switches connected in parallel for switching a total current I_tot. The method starts in step 210. The common control signal SI is received in step 220. In step 230, the individual control signals SI1 . . . SIn are ascertained depending on the control signal SI. In step 240, the individual control signals SI1 . . . SIn are output for controlling the power semiconductor switches. The method ends with step 250.