Direct-current transformer device and method for operating direct-current transformer device

Abstract

The invention relates to a DC-DC transformer arrangement having at least one DC-DC transformer, the DC-DC transformer having a current control and a voltage control. In this case, for the current regulation, the first component is provided for regulation on the basis of the current on the primary side of the DC-DC transformer, and the second component is provided for regulation on the basis of the current on the secondary side of the DC-DC transformer.

Description

Technical Field

[0001] The invention relates to a DC transformer device and a method for operating a DC transformer device. Background Art

[0002] Vehicles that are fully or at least partially electrically driven usually have an electrical energy storage device, such as a traction battery. The traction battery provides the electrical energy required to drive the electric vehicle. The traction battery usually provides an output voltage of several hundred volts and feeds the so-called high-voltage power grid of the vehicle. In addition, such vehicles usually include a plurality of electrical loads, which are supplied with a lower voltage via the low-voltage power grid. In order to couple the high-voltage power grid and the low-voltage power grid and in particular to transfer electrical energy from the high-voltage power grid to the low-voltage power grid, a so-called DC transformer can be provided, which converts the DC voltage of the high-voltage power grid into a DC voltage for the low-voltage power grid.

[0003] The published patent application DE 2009 028 147 A1 describes a circuit arrangement for an onboard power supply of an electric vehicle, in which a DC / DC converter is provided for coupling between two onboard power supplies. Summary of the invention

[0004] The invention discloses a DC transformer arrangement and a method for operating a DC transformer arrangement having the features of the independent claims. Further advantageous embodiments are the subject matter of the dependent claims.

[0005] Set accordingly:

[0006] A DC transformer device, which has at least one DC transformer and a control device. At least one DC transformer is designed to convert an input DC voltage into an output DC voltage. The control device includes a voltage regulator and a current regulator. The voltage regulator is designed to determine a first regulating variable for the DC transformer using a target value for the output voltage of the DC transformer and a measured value for the output voltage of the DC transformer. The current regulator includes a first regulating device and a second regulating device. The first regulating device is designed to determine a first current regulating variable using a current at the input end of the DC transformer. The second regulating device is designed to determine a second current regulating variable using a current at the output end of the DC transformer. The current regulator is designed to determine a second regulating variable using the first current regulating variable and the second current regulating variable; finally, the control device is designed to control the DC transformer using a combination of the first regulating variable and the second regulating variable.

[0007] In addition, set:

[0008] A method for operating a DC converter device having at least one DC converter. The method comprises a step for obtaining a first regulating variable using a target value for an output voltage of the DC converter and a measured value for the output voltage of the DC converter. Further, the method comprises a step for obtaining a first current regulating variable using a current at an input of the DC converter. In addition, the method comprises: a step for obtaining a second current regulating variable using a current at an output of the DC converter; a step for obtaining a second regulating variable for the DC converter using the first current regulating variable and the second current regulating variable; and a step for controlling at least one DC converter using a combination of the first regulating variable and the second regulating variable.

[0009] Advantages of the present invention.

[0010] The invention is based on the knowledge that the current on the output side or the secondary side can also be taken into account for the regulation of the DC transformer. In particular, if a transformer is provided in the DC transformer, the calculation of the output current limit value must be converted taking into account the transformation ratio of the transformer. However, such a conversion requires a certain amount of computing time, which can lead to delays during regulation. Such delays can lead to oscillations in the system.

[0011] The idea of ​​the present invention is therefore to take this knowledge into account and to implement a regulator structure for a DC transformer device, which regulator structure has a robust regulation characteristic. To this end, it is provided according to the invention that two independent parts for current regulation are provided in the regulation structure. In particular, independent current regulation is provided for the current on the input side or primary side and the current on the output side or secondary side. In this way, the detected current value can be directly supplied to the corresponding regulation structure without the need for performing a computationally intensive conversion.

[0012] In particular, the currents on the primary side or input side and on the secondary side or output side can be used independently of one another for the current control.

[0013] By means of such a control structure with separate current regulators for the primary side or input side and the secondary side or output side, requirements regarding hardware protection, such as the current limitation required here, can be implemented more easily. In particular, sensor tolerances and component tolerances have less influence on the system behavior here.

[0014] According to one embodiment, the current regulator is designed to select the smaller value from the first current regulating variable and the second current regulating variable as the second regulating variable. In other words, the current regulator selects the minimum value from the two current regulating variables as the regulating variable, and the two current regulating variables are obtained with respect to the primary side or the secondary side of the DC transformer, respectively. This ensures that the DC transformer is always operated below the maximum permissible current.

[0015] According to one embodiment, the first regulating device is designed to determine the first current regulating variable by comparing the current at the input of the DC transformer with a predetermined target value for the current at the input of the DC transformer. Correspondingly, the second regulating device can be designed to determine the second current regulating variable by comparing the current at the output of the DC transformer with a predetermined target value for the current at the output of the DC transformer. Furthermore, in this case, the current regulator can be designed to determine the second regulating variable by using the minimum value of the first current regulating variable and the second current regulating variable. In this way, the current regulator can be implemented particularly easily and efficiently.

[0016] According to one embodiment, the first regulating device and the second regulating device of the converter are each designed to output a control signal if the corresponding regulating device is active in an operating mode in which the maximum current in the DC converter is limited. In this case, the voltage regulator is designed to set the first regulating variable using the control signal of the current regulator. In this way, it is possible to limit or interrupt the voltage regulation in the voltage regulator if the DC converter is limited by the current regulation in the current regulator.

[0017] According to one embodiment, the DC transformer device comprises a plurality of DC transformers. In this case, an independent current regulator is provided for each DC transformer in the DC transformer device. In addition, a common voltage regulator is provided for all DC transformers in the DC transformer device. In this way, the power of the DC transformer device can be increased by connecting a plurality of DC transformers in parallel. In this case, the total power can be easily distributed between the individual voltage regulators by independent current regulation for each DC transformer.

[0018] According to one embodiment, the DC transformer comprises a flyback DC transformer. Since such a flyback DC transformer has a transformer in its circuit, the transformation ratio of the transformer used here can be easily and efficiently incorporated into the current control by means of separate current control for the primary side or input side and the secondary side or output side.

[0019] According to one specific embodiment, the control device is designed to output a pulse duty factor for pulse width modulation as a manipulated variable for controlling the DC converter. The DC converter can thus be easily controlled via pulse width modulation (PWM).

[0020] As long as it makes sense, the above-mentioned designs and improvements can be combined with each other arbitrarily. Other designs, improvements and implementations of the present invention also include combinations of features of the present invention described above or below with respect to the embodiments that are not explicitly mentioned. In particular, those skilled in the art will also add various aspects as improvements or supplements to the corresponding basic forms of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following is an explanation of the other features and advantages of the present invention with reference to the accompanying drawings. It is shown here:

[0022] Figure 1 A schematic diagram of a DC transformer device having a control device according to one embodiment is shown;

[0023] Figure 2 shows a schematic diagram of a DC converter device with a control device according to another embodiment, and

[0024] Figure 3 A flow chart is shown on which a method according to one specific embodiment is based.

[0025] In the figures, identical reference signs denote identical or functionally identical components, unless otherwise indicated. DETAILED DESCRIPTION

[0026] Figure 1 A schematic block diagram is shown on which a DC converter device with a control device 1 and a DC converter 2 according to one embodiment can be based. The DC converter 2 converts a DC voltage U_in provided on the input side into an output DC voltage U_out. The DC converter 2 can provide a control variable R, for example in the form of a duty cycle for pulse width modulated (PWM) control. The basic principle of a DC converter with pulse width modulated control is assumed to be known here and is not explained in more detail.

[0027] For example, a manipulated variable R for the DC converter 2 can be provided by means of the control device 1 . For this purpose, the control device 1 can include a voltage regulator 11 and a current regulator 12 .

[0028] The voltage regulator 11 generates a first control variable R1. To this end, the voltage regulator 11 compares the value of the output DC voltage U_out with a predefined target value U_soll. The target value U_soll can be, for example, the value of the target voltage to which the intermediate circuit capacitor 4 should be charged. In addition to the actual voltage regulator 11a, the voltage regulator 11 can also include a further pre-regulator 11b. The pre-regulator 11b can, for example, obtain a control component based on the input DC voltage U_in, the target voltage U_soll and, if necessary, also based on the current at the input and / or output of the DC transformer 2. The control component can be as follows Figure 1 The control components shown in FIG. 1 are combined with the control components of the actual voltage regulator 11 a in order to obtain the first controlled variable R1 .

[0029] The current regulator 12 generates a second control variable R2, which is obtained, for example, based on the current in the DC transformer 2. In this case, both the primary-side current I_p at the input of the DC transformer 2 and the secondary-side current I_s at the output of the DC transformer 2 can be taken into account for current regulation. For such current regulation, two independent regulating devices 12a and 12b are provided in the current regulator 12.

[0030] The first regulating device 12a can determine a first current regulating variable R_i_1. Here, the first current regulating variable R_i_1 is determined based on the current I_p on the primary side of the DC transformer 2. By means of the first current regulating variable R_i_1, for example, the current at the input of the DC transformer 2 can be limited to a predetermined maximum value. If necessary, the limit value can be adapted taking into account other parameters, such as, for example, the temperature in or at the DC transformer 2.

[0031] The second regulating device 12b can also obtain a second current regulating variable R_i_2. Here, the second current regulating variable R_i_2 is obtained based on the current I_s on the secondary side at the output of the DC transformer 2. By means of the second current regulating variable R_i_2, for example, the current at the output of the DC transformer 2 can be limited to a predetermined maximum value. If necessary, the limit value can also be adapted taking into account other parameters, such as, for example, the temperature at the DC transformer 2.

[0032] Thus, the current regulator 12 can determine the second control variable R2 from the acquired current control variables R_i_1 and R_i_2. The second control variable R2 can be formed, for example, by the minimum value of the first current control variable R_i_1 and the second current control variable R_i_2. In this way, it is ensured that the current in the DC converter 2 does not exceed the limit set by the current control variables R_i_1 and R_i_2.

[0033] If the current in the DC transformer 2 is limited by the current regulator 2, this can be signaled at the current regulator 11 by a corresponding signal C_1 of the first regulating device 12a and a signal C_2 of the second regulating device 12b. In this case, the regulation of the current regulator 11 can be adapted or deactivated in a suitable manner. This ensures that the regulation of the current regulator 11 does not have a counter-effect on the current regulation of the current regulator 12.

[0034] The first manipulated variable R1 of the voltage regulator 11 and the second manipulated variable R2 of the current regulator 12 can be combined with one another, for example added together, and the result can be made available as manipulated variable R to the DC converter 2 .

[0035] The DC transformer 2 can be, for example, a so-called flyback DC transformer. However, since the basic structure of such DC transformers, in particular flyback DC transformers, is also known, it will not be discussed in more detail here.

[0036] It is also possible to arrange multiple DC transformers 2 in parallel in the DC transformer device. In this case, an independent current regulator 12 can be provided for each DC transformer in the DC transformer 2, as described above. In addition, a common current regulator 11 can be provided for the entire DC transformer device.

[0037] Figure 2 1 shows a schematic block diagram on which a DC converter arrangement with a control device 1 and a DC converter 2 according to another embodiment can be based. Figure 1 The aforementioned embodiments of the DC converter arrangement already described also apply in principle.

[0038] according to Figure 2 The DC transformer device of the present invention is different from the DC transformer device described above in that, in the first regulating device 12a, the current I_p on the primary side is first compared with a predetermined target value I_p_target. For this purpose, for example, a difference between the current I_p on the primary side and the predetermined target value I_p_target can be formed. If necessary, the result of this comparison can also be weighted with a weighting factor g1. The first regulating device 12a can provide a first current regulating variable R_i_1 as an output value.

[0039] Similarly, in the second regulating device 12b, the current I_s on the secondary side can be compared with a predetermined target value I_s_target. For this purpose, a difference between the current I_s on the secondary side and the corresponding predetermined target value I_s_target can also be formed. If necessary, this result of the comparison can also be weighted with a weighting factor g2. The second regulating device 12b provides a second current regulating variable R_i_2 as an output value.

[0040] Thus, one of the two current manipulated variables R_i_1 or R_i_2 can be selected from the first current manipulated variable R_i_1 and the second current manipulated variable R_i_2. For example, the smaller of the two R_i_1 or R_i_2 can be selected and provided to the common controller logic 12c. The controller logic thus acquires the second manipulated variable R2. This second manipulated variable R2 can be combined with the first manipulated variable R1, as has already been described in connection with Figure 1 As described.

[0041] Figure 3 A flow chart is shown on which a method for operating a DC converter device according to one embodiment is based. The method can in principle include the above-described method in combination with the method according to Figure 1 and Figure 2 Similarly, the DC transformer device described above can also have any suitable components required to implement the method described below.

[0042] In a first step S1 , a first manipulated variable R1 is first determined. The first manipulated variable R2 can be determined using a target value U_target for the output voltage of the DC converter 2 and a measured value U_out for the output voltage of the DC converter 2 .

[0043] In step S2 , a first current manipulated variable R_i_1 is determined using the current I_p at the input of the DC converter 2 .

[0044] In step S3 , a second current manipulated variable R_i_2 is determined using the current I_s at the output of the DC converter 2 .

[0045] Thus, in step S4 , a second manipulated variable R2 is determined for the DC converter 2 using the first current manipulated variable R_i_1 and the second current manipulated variable R_i_2 .

[0046] Finally, in step S5 , the DC converter 2 can be controlled using a combination of the first manipulated variable R1 and the second manipulated variable R2 .

[0047] In summary, the invention relates to a DC transformer device having at least one DC transformer, wherein the DC transformer has current regulation and voltage regulation. In this case, for the current regulation, a first component is provided for regulation based on the current on the primary side at the DC transformer, and a second component is provided for regulation based on the current on the secondary side at the DC transformer.

Claims

1. A DC transformer device having: a DC transformer (2) designed to convert an input DC voltage into an output DC voltage; and A control device (1) comprising: A voltage regulator (11) is designed to determine a first control variable (R1) for the DC converter (2) using a target value (U_target) for the output voltage of the DC converter (2) and a measured value (U_out) for the output voltage of the DC converter (2), and A current regulator (12) which is designed to determine a second control variable (R2) for the DC transformer (2); in, The current regulator (12) comprises a first regulating device (12a) and a second regulating device (12b), The first regulating device (12a) is designed to determine a first current regulating variable (R_i_1) using the current (I_p) at the input of the DC transformer (2), The second regulating device (12b) is designed to determine a second current regulating variable (R_i_2) using the current (I_s) at the output of the DC transformer (2), and The current regulator (12) is designed to determine the second manipulated variable (R2) using the first current manipulated variable (R_i_1) and the second current manipulated variable (R_i_2); and The control device (1) is designed to control the DC converter (2) using a combination (R) of the first manipulated variable (R1) and the second manipulated variable (R2).

2. The DC transformer device according to claim 1, wherein: The current regulator (12) is designed to select the smaller value of the first current manipulated variable (R_i_1) and the second current manipulated variable (R_i_2) as a second manipulated variable (R2).

3. The DC transformer device according to claim 1 or 2, wherein: The first regulating device (12a) and the second regulating device (12b) of the current regulator (12) are respectively designed to output a control signal (C1, C2) if the corresponding regulating device (12a, 12b) is activated in an operating mode in which a maximum current in the DC transformer (2) is limited, and the voltage regulator (11) is designed to set the first regulating variable (R1) using the control signal (C1, C2) of the current regulator (12).

4. The DC transformer device according to claim 1, wherein: The first regulating device (12a) is designed to determine the first current regulating variable (R_i_1) by comparing the current (I_p) at the input of the DC transformer (2) with a predetermined target value (I_p_target) for the current at the input of the DC transformer (2). The second regulating device (12b) is designed to determine the second current regulating variable (R_i_2) by comparing the current (I_s) at the output of the DC transformer (2) with a predetermined target value (I_s_target) for the current at the output of the DC transformer (2), and The current regulator (12) is designed to determine the second manipulated variable (R2) using a minimum value of the first current manipulated variable (R_i_1) and the second current manipulated variable (R_i_2).

5. The DC transformer device according to any one of claims 1 to 4, wherein: The DC transformer device comprises a plurality of DC transformers (2), wherein an independent current regulator (12) is provided for each DC transformer (2) in the DC transformer device, and wherein a common voltage regulator (11) is provided for all DC transformers (2) of the DC transformer device.

6. The DC transformer device according to any one of claims 1 to 5, wherein: The DC transformer (2) comprises a flyback DC transformer.

7. The DC transformer device according to any one of claims 1 to 6, wherein: The control device (1) is designed to output a pulse duty factor for pulse width modulation as a manipulated variable (R) for actuating the DC converter (2).

8. A method for operating a DC converter device having at least one DC converter (2), the method comprising the steps of: Acquiring (S1) a first control variable (R1) using a target value (U_target) for the output voltage of the DC transformer (2) and a measured value (U_out) for the output voltage of the DC transformer; Acquiring (S2) a first current regulating variable (R_i_1) using the current (I_p) at the input end of the DC transformer (2); Acquiring (S3) a second current regulating variable (R_i_2) using the current (I_s) at the output end of the DC transformer (2); Acquiring (S4) a second regulating variable (R_2) for the DC converter (2) using the first current regulating variable (R_i_1) and the second current regulating variable (R_i_2); and The at least one DC converter (2) is controlled (S5) using a combination (R) of the first manipulated variable (R1) and the second manipulated variable (R2).

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