METHOD AND ARRANGEMENT FOR ACTUATING A METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR

Abstract

The invention relates to a method and an actuating arrangement for controlling a MOSFET, in particular wide-bandgap MOSFET. A change of an actuating variable, which actuates the MOSFET as a function of an operating characteristic variable that influences the switching behavior of the MOSFET is stored in a characteristic block. The change counteracts a reference actuating value of the actuating variable. An actual value of the operating characteristic variable is determined during operation of the MOSFET, The actuating variable is changed from the reference actuating value as a function of the actual value commensurate with the change of the actuating variable stored in the characteristic block. The change stored in the characteristic block can include a change in the switch-on or switch-off voltage or gate resistance of the MOSFET as a function of the operating temperature or the operating voltage of the MOSFET.

Claims

1.-15. (canceled)

16. A method for actuating a metal-oxide-semiconductor field-effect transistor (MOSFET), in particular a wide-bandgap MOSFET, comprising: storing in a characteristic block a change of at least one actuating variable, which actuates the MOSFET as a function of at least one operating characteristic variable that influences the switching behavior of the MOSFET, with the change counteracting a reference actuating value of the actuating variable; ascertaining during operation of the MOSFET an actual value of the at least one operating characteristic variable; and changing the at least one actuating variable from the reference actuating value commensurate with the change of at least one actuating variable stored in the characteristic block, depending on the actual value of the at least one operating characteristic variable.

17. The method of claim 18, further comprising storing in the characteristic block a change of a switch-on actuating voltage for switching on the MOSFET as a function of the at least one operating characteristic variable.

18. The method of claim 18, further comprising storing in the characteristic block a change of a switch-off actuating voltage for switching off the MOSFET as a function of the at least one operating characteristic variable.

19. The method of claim 16, further comprising storing in the characteristic block a change of a switch-on gate resistance for switching on the MOSFET as a function of the at least one operating characteristic variable.

20. The method of claim 16, further comprising storing in the characteristic block a change of a switch-off gate resistance for switching off the MOSFET as a function of the at least one operating characteristic variable.

21. The method of claim 16, further comprising storing in the characteristic block a change of the at least one actuating variable selected from a switch-on actuating voltage for switching on the MOSFET, a switch-off actuating voltage for switching off the MOSFET, a switch-on gate resistance for switching on the MOSFET and a switch-off gate resistance for switching off the MOSFET as a function of an operating voltage of the MOSFET.

22. The method of claim 16, further comprising storing in the characteristic block a change of the at least one actuating variable selected from a switch-on actuating voltage for switching on the MOSFET, a switch-off actuating voltage for switching off the MOSFET, a switch-on gate resistance for switching on the MOSFET and a switch-off gate resistance for switching off the MOSFET as a function of an operating temperature of the MOSFET.

23. An actuating arrangement for controlling a metal-oxide-semiconductor field-effect transistor (MOSFET), in particular a wide-bandgap MOSFET, said actuating arrangement comprising: an evaluation unit receiving at least one operating characteristic variable of the MOSFET that influences a switching behavior of the MOSFET, said evaluation unit comprising a characteristic block storing a change of at least one actuating variable of the MOSFET compared to a reference actuating value as a function of the at least one operating characteristic variable, and a control unit receiving a control signal and producing a changed actuating value of the at least one actuating variable, wherein the changed actuating value is changed from the reference actuating value of the actuating variable commensurate with the change of the at least one actuating variable ascertained by the evaluation unit, and actuating the MOSFET in response to a control signal with the changed actuating value.

24. The actuating arrangement of claim 23, wherein the control unit comprises a controllable switch-on voltage source for generating a variable switch-on actuating voltage for switching on the MOSFET.

25. The actuating arrangement of claim 23, wherein the control unit comprises a controllable switch-off voltage source for generating a variable switch-off actuating voltage for switching off the MOSFET.

26. The actuating arrangement of claim 23, wherein the control unit comprises a controllable switch-on resistance unit for generating a variable switch-on gate resistance for switching on the MOSFET.

27. The actuating arrangement of claim 23, wherein the control unit comprises a controllable switch-off resistance unit for generating a variable switch-off gate resistance for switching off the MOSFET.

28. The actuating arrangement of claim 23, further comprising a measurement apparatus configured to measure actual values of the at least one operating characteristic variable which affects the switching behavior of the MOSFET.

29. The actuating arrangement of claim 28, wherein the actual values includes at least one actual value selected from a measured operating voltage and a measured operating temperature of the MOSFET.

30. A current converter, in particular a traction current converter, comprising: at least one metal-oxide-semiconductor field-effect transistor (MOSFET) and; and an actuating arrangement for controlling the MOSFET, said actuating arrangement comprising: an evaluation unit receiving at least one operating characteristic variable of the MOSFET that influences a switching behavior of the MOSFET, said evaluation unit comprising a characteristic block storing a change of at least one actuating variable of the MOSFET compared to a reference actuating value as a function of the at least one operating characteristic variable, and a control unit receiving a control signal and producing a changed actuating value of the at least one actuating variable, wherein the changed actuating value is changed from the reference actuating value of the actuating variable commensurate with the change of the at least one actuating variable ascertained by the evaluation unit, and actuating the MOSFET in response to a control signal with the changed actuating value.

Description

[0015] The above-described properties, features and advantages of this invention, as well as the manner in which they are realized, will become clearer and more intelligible in conjunction with the following description of exemplary embodiments which are explained in more detail in conjunction with the drawings, in which:

[0016] FIG. 1 shows a circuit diagram of a MOSFET and a first exemplary embodiment of an actuating arrangement for actuating the MOSFET,

[0017] FIG. 2 shows a circuit diagram of a control unit for actuating a MOSFET,

[0018] FIG. 3 shows a characteristic curve for a change to a switching-on actuating voltage as a function of an operating voltage of a MOSFET,

[0019] FIG. 4 shows a circuit diagram of a current converter,

[0020] FIG. 5 shows a flow diagram of a method for actuating a MOSFET.

[0021] Parts which correspond to one another are provided with the same reference characters in the figures.

[0022] FIG. 1 shows a circuit diagram of a MOSFET 1 and a first exemplary embodiment of an actuating arrangement 3 according to the invention for actuating the MOSFET 1.

[0023] The MOSFET 1 is embodied as a normally blocking n-channel MOSFET, which is based on a semiconductor with a wide band gap, for example on silicon carbide or gallium nitride.

[0024] The actuating arrangement 3 comprises a control unit 5, an evaluation unit 7 and a measurement apparatus 9.

[0025] The measurement apparatus 9 is embodied to capture an operating temperature T and an operating voltage U of the MOSFET 1 as operating variables T, U. In order to capture the operating temperature T, the measurement apparatus 9 has a temperature sensor 11, for example an NTC resistor (negative temperature coefficient thermistor). The operating voltage U, for example, is measured as a drain-source voltage of the MOSFET 1 between drain D and source S in the switched-off state of the MOSFET 1.

[0026] FIG. 2 shows a schematic circuit diagram of the control unit 5. The control unit 5 comprises a controllable switching-on voltage source 13 for generating a variable switching-on actuating voltage U1 for switching on the MOSFET 1, a controllable switching-off voltage source 15 for generating a variable switching-off actuating voltage U2 for switching off the MOSFET 1, a controllable switching-on resistance unit 17 for generating a variable switching-on gate resistance R1 for switching on the MOSFET 1, a controllable switching-off resistance unit 19 for generating a variable switching-off gate resistance R2 for switching off the MOSFET 1, a first terminal 21 connected to the gate G of the MOSFET 1 and a second terminal 23 connected to the source S of the MOSFET 1. The switching-on resistance unit 17 and the switching-off resistance unit 19, for example, each have a $ large number of individual resistors, wherein in order to set a particular switching-on gate resistance R1 or switching-off gate resistance R2, a number of individual resistors required for this purpose can be interconnected to one another in each case.

[0027] In each case, a first pole of the switching-on voltage source 13 and a first pole of the switching-off voltage source 15 are permanently connected to the second terminal 23. In order to switch on the MOSFET 1, the second pole of the switching-on voltage source 13 is connected to the first terminal 21 via the switching-on resistance unit 17 by closing a first switch 25, and the second pole of the switching-off voltage source 15 is disconnected from the switching-off resistance unit 19 and the first terminal 21 by opening a second switch 27. In order to switch off the MOSFET 1, the second pole of the switching-off voltage source 15 is connected to the first terminal 21 via the switching-odd resistance unit 19 by closing the second switch 27, and the switching-on voltage source 13 is disconnected from the switching-on resistance unit 17 and the first terminal 21 by opening the first switch 25. The switching on and off of the MOSFET 1 is triggered by a binary control signal 12 supplied to the control unit 5.

[0028] The switching-on actuating voltage U1 used to switch on the MOSFET 1 and the switching-on gate resistance R1 used to switch on the MOSFET 1, as well as the switching-off actuating voltage U2 used to switch off the MOSFET 1 and the switching-off gate resistance R2 used to switch off the MOSFET 1 are actuating variables U1, U2, R1, R2 for actuating the MOSFET 1, which are each set as a function of the operating temperature T and the operating voltage U of the MOSFET 1. To this end, stored in the evaluation unit 7 is a characteristic block, in which changes ΔU1, ΔU2, ΔR1, ΔR2 to said actuating variables U1. U2. R1, R2 compared to a reference actuating value as a function of the operating temperature T and the operating voltage U are recorded in each case, which changes counteract a change in the switching behavior of the MOSFET 1 caused by the operating temperature T or operating voltage U.

[0029] For the operating temperature T and the operating voltage U, which are captured by the measurement apparatus 9, the evaluation unit 7 uses the characteristic block to ascertain changes ΔU1, ΔU2, ΔR1, ΔR2 to the actuating variables U1, U2, R1, R2 compared to the respective reference actuating values thereof and transmits the changes ΔU1, ΔU2, ΔR1 ΔR2 to the control unit 5. The control unit 5 sets the switching-on actuating voltage U1, the switching-off actuating voltage U2, the switching-on gate resistance R1 and the switching-off gate resistance R2 to the respective actuating value which is changed compared to the reference actuating value.

[0030] FIG. 3 shows, by way of example, a characteristic curve of the characteristic block for a change ΔU1 to the switching-on actuating voltage U1 as a function of the operating voltage U compared to the reference actuating value for the switching-on actuating voltage U1, The value ΔU1 resulting from the characteristic curve for an operating voltage U is added to the reference actuating value for the switching-on actuating voltage U1.

[0031] FIG. 4 shows a circuit diagram of a current converter 30 with a MOSFET 1 and a second exemplary embodiment of an actuating arrangement 3 according to the invention for actuating the MOSFET 1. The current converter 30, for example, is a traction current converter with further MOSFETs 1 (not shown here), which are interconnected to form half bridges or full bridges in a known manner, and a further actuating arrangement 3 for each further MOSFET 1. The actuating arrangements 3 of this exemplary embodiment only differ from the exemplary embodiment shown in FIG. 1 in that they have no measurement apparatus 9 for capturing the operating temperature T and the operating voltage U of the MOSFET 1. Instead, actual values of the operating temperature T and the operating voltage U are supplied to the evaluation unit 7 of each actuating arrangement 3 by a controller 29 of the current converter 30, which also sends the control signal 12 to the control unit 6 of the actuating arrangement 3.

[0032] FIG. 5 shows a flow diagram of an exemplary embodiment of the method according to the invention for actuating a MOSFET 1 with an actuating arrangement 3 designed according to FIG. 1 or FIG. 4.

[0033] In a first method step S1, a characteristic block is created, in which a change ΔU1 to the switching-on actuating voltage U1, a change ΔU2 to the switching-off actuating voltage U2, a change ΔR1 to the switching-on gate resistance R1 and a change ΔR2 to the switching-off gate resistance R2, in each case as a function of the operating temperature T and the operating voltage U of the MOSFET 1, are recorded. The characteristic block is stored in the evaluation unit 7 of the actuating arrangement 3.

[0034] In a second method step S2, the instantaneous operating temperature T and the instantaneous operating voltage U of the MOSFET 1 (i.e. actual values of the operating temperature T and the operating voltage U) are ascertained and supplied to the evaluation unit 7.

[0035] In a third method step S3, for the values of the operating temperature T and the operating voltage U ascertained in the second method step S2, the evaluation unit 7 uses the characteristic block to ascertain changes ΔU1, ΔU2, ΔR1, ΔR2 to the switching-on actuating voltage U1, the switching-off actuating voltage U2, the switching-on gate resistance R1 and the switching-off gate resistance R2 compared to the respective reference actuating values thereof and transmit these to the control unit 5.

[0036] In a fourth method step S4, the control unit 5 sets the switching-on actuating voltage U1, the switching-off actuating voltage U2, the switching-on gate resistance R1 and the switching-off gate resistance R2 to an actuating value in each case, which is changed compared to the respective reference actuating value by adding the change ΔU1, ΔU2, ΔR1, ΔR2 ascertained in the third method step S3 to the reference actuating value. Following the fourth method step S4, the method is continued with the second method step S2.

[0037] The exemplary embodiments of an actuating arrangement 3 according to the invention and the method according to the invention, which are described on the basis of the figures, can be modified in various ways to form alternative exemplary embodiments. For example, changes ΔU1, ΔU2, ΔR1, ΔR2 to the switching-on actuating voltage U1, the switching-off actuating voltage U2, the switching-on gate resistance R1 and the switching-off gate resistance R2 compared to respective reference actuating values may be ascertained and set as a function of either only the operating temperature T or only the operating voltage U, instead of as a function of both the operating temperature T and the operating voltage U. Furthermore, provision may be made to ascertain and set changes ΔU1, ΔU2, ΔR1, ΔR2 only to a subset of the actuating variables U2, U2, R1, R2 compared to respective reference actuating values as a function of the operating temperature T and/or the operating voltage U, for example only changes ΔU1, ΔU2 to the switching-on actuating voltage U1 and the switching-off actuating voltage U2 or only changes ΔR1, ΔR2 to the switching-on gate resistance R1 and the switching-off gate resistance R2. Furthermore, in the case of taking into consideration the operating temperature T, provision may be made to ascertain the instantaneous operating temperature T of the MOSFET 1 on the basis of a temperature-dependent electrical parameter of the MOSFET 1, for example as in M. Denk and M. M. Bakran, “IGBT Gate Driver with Accurate Measurement of Junction Temperature and Inverter Output Current,” PCIM Europe 2017; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg, Germany, 2017, pp. 1-8, or to determine the instantaneous operating temperature T with the aid of a model which estimates the operating temperature T using other operating conditions.

[0038] Exemplary embodiments of a current converter 19 alternative to FIG. 4 result from replacing the actuating arrangement 3 shown in FIG. 4 with an actuating arrangement 3 of the exemplary embodiment described in FIG. 1 or one of the modified exemplary embodiments previously mentioned.

[0039] Although the invention has been illustrated and described in greater detail on the basis of preferred exemplary embodiments, the invention is not limited by the disclosed examples and other variations can be derived herefrom by the person skilled in the art without departing from the scope of protection of the invention.