Method for determining at least one characteristic parameter of a component of a DC converter by way of an electronic computer device, and electronic computer device

Abstract

A method for determining at least one characteristic parameter of a component of a DC converter for an on-board electrical system of a motor vehicle by way of an electronic computer device includes determining a first transfer function of an HV/LV DC converter based on a small-signal model of the HV/LV DC converter, determining a second transfer function of the DC converter according to the first transfer function in such a way that the DC converter has at least one characteristic substantially identical to a characteristic of the HV/LV DC converter, and determining the at least one characteristic parameter of the component of the DC converter according to the second transfer function.

Claims

1. A method for determining a characteristic parameter of a component of a DC-DC voltage converter for an on-board electrical system of a motor vehicle by way of an electronic computing device, the method comprising: determining a first transfer function of an HV/LV DC-DC voltage converter based on a small-signal response of the HV/LV DC-DC voltage converter, determining a second transfer function of the DC-DC voltage converter depending on the first transfer function such that the DC-DC voltage converter has a property that is substantially identical to a property of the HV/LV DC-DC voltage converter, determining the characteristic parameter of the component of the DC-DC voltage converter depending on the second transfer function, and adjusting the characteristic parameter such that the property of the HV/LV DC-DC voltage converter is adopted by the DC-DC voltage converter, wherein the HV/LV DC-DC voltage converter and the DC-DC voltage converter are each provided as bidirectional DC-DC voltage converters, such that the DC-DC voltage converter is able to be used in a highly flexible manner within the on-board electrical system of the motor vehicle.

2. The method according to claim 1, wherein: the characteristic parameter is determined such that the DC-DC voltage converter has a step response that is substantially identical to a step response of the HV/LV DC-DC voltage converter.

3. The method according to claim 1, wherein: the characteristic parameter is determined such that the DC-DC voltage converter has a Bode plot that is substantially identical to a Bode plot of the HV/LV DC-DC voltage converter.

4. The method according to claim 1, wherein: the HV/LV DC-DC voltage converter and the DC-DC voltage converter are each provided as a full bridge.

5. The method according to claim 1, wherein: the HV/LV DC-DC voltage converter and the DC-DC voltage converter are each provided as electrically isolated DC-DC voltage converters.

6. The method according to claim 1, wherein: the characteristic parameter is a value of a leakage inductance as the component of the DC-DC voltage converter.

7. The method according to claim 1, wherein: the characteristic parameter is a value of a duty cycle as the component of the DC-DC voltage converter.

8. The method according to claim 1, wherein: a transformation ratio of the HV/LV DC-DC voltage converter and a transformation ratio of the DC-DC voltage converter are taken into account when determining the characteristic parameter.

9. An electronic computing device for determining the characteristic parameter of the component of the DC-DC voltage converter for the on-board electrical system of the motor vehicle, wherein the electronic computing device is configured to carry out the method according to claim 1.

10. A method for determining a characteristic parameter of a component of a DC-DC voltage converter for an on-board electrical system of a motor vehicle by way of an electronic computing device, the method comprising: determining a first transfer function of an HV/LV DC-DC voltage converter based on a small-signal response of the HV/LV DC-DC voltage converter, determining a second transfer function of the DC-DC voltage converter depending on the first transfer function such that the DC-DC voltage converter has a property that is substantially identical to a property of the HV/LV DC-DC voltage converter, determining the characteristic parameter of the component of the DC-DC voltage converter depending on the second transfer function, and adjusting the characteristic parameter such that the property of the HV/LV DC-DC voltage converter is adopted by the DC-DC voltage converter, wherein the characteristic parameter is determined such that the DC-DC voltage converter has a Bode plot that is substantially identical to a Bode plot of the HV/LV DC-DC voltage converter, such that the DC-DC voltage converter can be used highly dynamically even for transient processes within the motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic block diagram of one embodiment of a DC-DC voltage converter.

(2) FIG. 2 shows a schematic flowchart of one embodiment of the method.

DETAILED DESCRIPTION OF THE DRAWINGS

(3) Identical or functionally identical elements are provided with the same reference signs in the figures.

(4) FIG. 1 shows a schematic view of a block diagram of a DC-DC voltage converter 10. In the present case, this block diagram can be considered both for the DC-DC voltage converter 10 and for an HV/LV DC-DC voltage converter 12. In a method for determining at least one characteristic parameter of a component of the DC-DC voltage converter 10 for an on-board electrical system of a motor vehicle 14, which is represented purely schematically, by way of an electronic computing device 16, which is likewise represented purely schematically, a first transfer function of the HV/LV DC-DC voltage converter 12 is determined based on a small-signal response of the HV/LV DC-DC voltage converter 12 and a second transfer function of the DC-DC voltage converter 10 is determined depending on the first transfer function in such a way that the DC-DC voltage converter 10 has at least one property that is substantially identical to that of the HV/LV DC-DC voltage converter 12, and the at least one parameter of the component of the DC-DC voltage converter 10 is determined depending on the second determined transfer function. In particular, provision can be made for the characteristic parameter determined to be a value of a leakage inductance LK as the component of the DC-DC voltage converter 10. Furthermore, the characteristic parameter determined can be a value of a duty cycle d as the component of the DC-DC voltage converter 10. Furthermore, a respective transformation ratio n of the HV/LV DC-DC voltage converter 12 and of the DC-DC voltage converter 10 can also be taken into account when determining the characteristic parameter.

(5) In particular, it is further shown that the DC-DC voltage converter 10 and the HV/LV DC-DC voltage converter 12 are respectively in the form of a full bridge 18. The HV/LV DC-DC voltage converter 12 and the DC-DC voltage converter 10 are in particular provided as electrically isolated DC-DC voltage converters 10, 12. In particular, the HV/LV DC-DC voltage converter 12 and the DC-DC voltage converter 10 thus have a transformer element 20. The HV/LV DC-DC voltage converter 12 and the DC-DC voltage converter 10 can in particular each be provided as bidirectional DC-DC voltage converters 10, 12. The HV/LV DC-DC voltage converter 12 and the DC-DC voltage converter 10 each have an input voltage Vin and an output voltage Vo. For example, the HV/LV DC-DC voltage converter 12 can have an input voltage Vin of 400 volts and the output voltage Vo can be 12 volts.

(6) The method according to embodiments of the invention now has provision for the DC-DC voltage converter 10 to be designed in such a way that, for example, the property of this described HV/LV DC-DC voltage converter 12 is adopted by the DC-DC voltage converter 10, wherein the DC-DC voltage converter 10 then has an input voltage Vin of 48 volts, for example, and has an output voltage Vo of 12 volts. These numbers are purely exemplary and are in no way to be regarded as definitive. Other input voltages Vin and output voltages can also be replicated. This applies to the input voltages Vin and output voltages Vo both for the HV/LV DC-DC voltage converter 12 and for the DC-DC voltage converter 10. It is known that an applicable DC-DC voltage converter 10 cannot be as dynamic as the HV/LV DC-DC voltage converter 12. In the present case, provision is now made for a dynamic performance that is identical to that of the HV/LV DC-DC voltage converter 12 to be found in the DC-DC voltage converter 10 by virtue of appropriate adjustment of the parameter.

(7) To this end, provision is in particular made for the HV/LV DC-DC voltage converter 12 to be formulated in state space as a small-signal model. The respective transfer functions of the HV/LV DC-DC voltage converter 12 and of the DC-DC voltage converter 10, which should have an identical response in both DC-DC voltage converters 10, 12, are established. The voltage, for example, is then scaled in such a way and the transfer function is examined for sensitivities. The sensitive transfer functions are then analyzed and the adjusted parameters are parameterized and determined.

(8) FIG. 2 shows a schematic flowchart of one embodiment of the method. In a first step, the respective parameters of the HV/LV DC-DC voltage converter 12 are determined. In particular, the input voltage Vin and the output voltage Vo of the HV/LV DC-DC voltage converter 12 are determined. Furthermore, the transformation ratio n, the leakage inductance LK and the duty cycle d are determined. In a second step S2, a factor Kv is determined depending on the input voltage Vin of the HV/LV DC-DC voltage converter 12 and of the DC-DC voltage converter 10 and the output voltages Vo of the HV/LV DC-DC voltage converter 12 and of the DC-DC voltage converter 10. To this end, the desired parameters 22 of the DC-DC voltage converter 10 are in particular taken into account. In a third step S3, the transformation ratio n of the HV/LV DC-DC voltage converter 12 is expressed in relation to the factor Kv and gives the new transformation ration of the DC-DC voltage converter 10. A fourth step S4 comprises checking whether the transformation ratio n of the DC-DC voltage converter 10 is also viable. Should this be the case, a further factor Kn corresponds to the factor Kv and the leakage inductance LK can be determined in a fifth step S5. In a sixth step S6, the leakage inductance LK of the DC-DC voltage converter 10 is then determined by expressing the leakage inductance LK of the HV/LV DC-DC voltage converter 12 in relation to the factor Kn squared. The seventh step S7 then comprises checking whether the determined leakage inductance LK of the DC-DC voltage converter 10 is determined to be too large or too small. Should this not be the case, the respective characteristic parameters of the DC-DC voltage converter 10 can be determined in an eighth step S8.

(9) Should it be determined in the fourth step S4 that the transformation ratio n of the DC-DC voltage converter 10 is viable, the transformation ratio n can be rounded in a ninth step S9. A new further factor Kn can then be determined, wherein this factor is in turn determined as the rounded transformation ratio depending on the transformation ratio n of the HV/LV DC-DC voltage converter 12. This is shown in particular in a tenth step S10. From the tenth step S10 it is then in turn possible to move to the sixth step S6 and the applicable leakage inductance LK can be determined.

(10) Should it be determined in the seventh step S7 that the determined leakage inductance LK is too large or too small, the transformation ratio n of the DC-DC voltage converter 10 can be re-adjusted in an eleventh step S11, wherein from the eleventh step S11 it is then in turn possible to move to the tenth step S10 and the new further factor Kn can be determined. Proceeding from the seventh step S7, should it be determined that the factor Kvis not equal to the factor Kn, the duty cycle d can be adjusted in a twelfth step S12. In particular, the ratio of Kv and Kn can be expressed in relation to the old duty cycle d of the HV/LV DC-DC voltage converter 12. From the twelfth step 12, it is then in turn possible to move to the eighth step S8.

(11) On the whole, the invention provides a method for voltage scaling of power electronic converters.

LIST OF REFERENCE SIGNS

(12) 10 DC-DC voltage converter 12 HV/LV DC-DC voltage converter 14 motor vehicle 16 electronic computing device 18 full bridge 20 transformer element 22 parameter S1 first step S2 second step S3 third step S4 fourth step S5 fifth step S6 sixth step S7 seventh step S8 eighth step S9 ninth step S10 tenth step S11 eleventh step S12 twelfth step n transformation ratio d duty cycle