DC voltage converter and method for operating a DC voltage converter

Abstract

The present invention relates to the control of a DC voltage converter, wherein the gradient of an adjustment parameter used for controlling the DC voltage converter is restricted. By restricting the gradient of the adjustment parameter, the maximum current change in the DC voltage converter can be restricted in order to avoid a dangerous operating state of the DC voltage converter if necessary.

Description

Field of the Invention

[0001] The present invention relates to a DC voltage converter and a method for operating a DC voltage converter. Background Art

[0002] The published document DE 10 2016 219 740 A1 discloses a DC voltage converter having a plurality of DC voltage converter modules connected in parallel. Here, a common voltage regulator is provided for all DC voltage converter modules. In addition, individual current regulation is provided for each DC voltage converter module.

[0003] The DC voltage converter is configured to convert an input DC voltage into an output DC voltage, wherein the voltage level of the input DC voltage can be different from the voltage level of the output DC voltage. By means of regulation, the output voltage and output current of the DC voltage converter can be regulated according to a predefined target value. Summary of the Invention

[0004] The present invention discloses a DC voltage converter and a method for operating a DC voltage converter having the features of the independent claims. Other advantageous embodiments are the subject matter of the dependent claims.

[0005] Accordingly, there is provided:

[0006] A DC voltage converter having a first regulating device, a second regulating device, a combining device, a third regulating device, and at least one DC voltage converter module. The first regulating device is designed to determine a first regulating parameter. In particular, the first regulating parameter can be determined in the case of using the value of the current input voltage, the value of the current input current, and the target value of the output voltage. The second regulating device is designed to determine a second regulating parameter. In particular, the second regulating parameter can be determined in the case of using the target value of the output voltage and the value of the current output voltage. The combining device is designed to combine the first regulating parameter and the second regulating parameter. The combination of the first and second regulating parameters can be output as a target regulating parameter. The third regulating device is designed to limit the gradient of the target parameter, that is, the gradient of the combination of the first and second regulating parameters, to a predefined minimum value and / or maximum value. The target regulating parameter limited by the third regulating device can be provided as an output regulating parameter. The at least one DC voltage converter module is designed to convert an input DC voltage into an output DC voltage in the case of using the output regulating parameter.

[0007] In addition, there is provided:

[0008] A method for operating a DC voltage converter. The method includes steps for determining a first adjustment parameter using the value of the current input voltage, the value of the current input current, and the target value for the output voltage. In addition, the method includes steps for determining a second adjustment parameter using the target value for the output voltage and the value of the current output voltage. Furthermore, the method includes steps for combining the first adjustment parameter and the second adjustment parameter into a target adjustment parameter and for limiting the gradient of the target adjustment parameter. In particular, the target adjustment parameter can be limited to a predetermined minimum value and / or a predetermined maximum value. The target adjustment parameter thus limited can be provided as an output adjustment parameter. Finally, the method can include steps for controlling at least one DC voltage converter module, wherein the DC voltage converter module can be controlled using the output adjustment parameter.

[0009] The present invention is based on the recognition that the current in a DC voltage converter can rise or fall very steeply if necessary according to the regulation characteristics, especially in boost operation. Such a very rapid change in the rise or fall of the current in the DC voltage converter can, if necessary, subject the electrical components in the DC voltage converter to very strong loads. This sometimes leads to damage to the components in the DC voltage converter.

[0010] Therefore, the idea of the present invention is to take this recognition into account and provide a regulation for the DC voltage converter that can prevent operating states with an overly strong rise or fall of the current in the DC voltage converter. For this purpose, it is provided that the gradient of the adjustment parameter used to control the DC voltage converter is limited. For example, the adjustment parameter can be the duty cycle for controlling the switching element in the DC voltage converter. Thus, by limiting the gradient in the adjustment parameter, the maximum rise or fall of the current in the DC voltage converter can also be limited. In addition, while observing the predetermined limits for the rise or fall of the current, the desired target voltage or the desired target current can be adjusted as quickly as possible without exceeding the overload limit for the components in the DC voltage converter.

[0011] According to one embodiment, the third regulating device is designed to limit the gradient of a target regulating parameter using the value for the current input voltage and the value for the current output voltage. The third regulating device can in particular determine the currently set regulating parameter in the DC voltage converter module, for example, from the value of the current input voltage and the value of the current output voltage for the current operating state. Accordingly, the gradient of the regulating parameter to be reset can be determined from the comparison between the current regulating parameter and a predefined target regulating parameter. If this gradient exceeds a predefined limit, the third regulating device can limit the regulating parameter to be reset to the regulating parameter according to the predefined limit.

[0012] According to one embodiment, the at least one DC voltage converter module includes a transformer. The transformer can in particular be arranged between the input connection and the output connection of the DC voltage converter module. In this case, the third regulating device can be designed to limit the gradient of the target regulating parameter using the transformation ratio of the transformer. The transformation ratio can in particular represent the turns ratio between the primary coil and the secondary coil of the transformer. In addition to the current input voltage and the current output voltage, this transformation ratio can also be taken into account for determining the current setting of the DC voltage converter.

[0013] According to one embodiment, the third regulating device is designed to limit the maximum current change in the DC voltage converter. The maximum current change can in particular relate to the input current or the output current of the DC voltage converter here. By limiting the current change and thus the current gradient in the DC voltage converter, it can be ensured that overloading of the components in the DC voltage converter can be avoided.

[0014] According to one embodiment, at least one DC voltage converter module of the DC voltage converter is operated in a boost converter operation mode. In particular, in boost converter operation, from a specific regulating parameter, in particular from a specific duty cycle, overloading of the components can occur in the case of strong current changes, and this overloading can always lead to damage to the components. By limiting the regulating parameter and thus the change in the current, such a dangerous operating state can be prevented.

[0015] As long as it makes sense, the above design solutions and improvement solutions can be combined with each other arbitrarily. Other design solutions, improvement solutions and implementation solutions of the present invention also include combinations of features not explicitly mentioned before or below in the description of the embodiments of the present invention. Here, those skilled in the art will in particular also add various aspects as improvements or supplements to the corresponding basic forms of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following explains other features and advantages of the present invention with the aid of the drawings. Among them:

[0017] Figure 1 A schematic diagram showing a block diagram of a DC voltage converter according to an embodiment;

[0018] Figure 2 A schematic diagram showing a block diagram as the basis of a regulating device of a DC voltage converter according to an embodiment; and

[0019] Figure 3 A schematic diagram showing a flowchart as the basis of a method for operating a DC voltage converter according to an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Figure 1 A schematic diagram showing a block diagram as the basis of a DC voltage converter 1 according to an embodiment. The DC voltage converter 1 can include one or more DC voltage converter modules 50, which convert an input DC voltage U_in into an output voltage U_out. Although only a single DC voltage converter module 50 is shown in Figure 1 , in principle, multiple DC voltage converter modules 50 can also be operated in parallel. The output voltage U_out and / or the output current can be adjusted by means of corresponding regulation here. A load, such as a capacitor C, can be connected to the output of the DC voltage converter 1.

[0021] In order to regulate the DC voltage converter 1, in particular the DC voltage converter module 50, a first regulating device 10 can be provided, for example. The first regulating device 10 can determine a first regulating parameter R1 within a pre-control range, for example. This first regulating parameter R1 can be determined, for example, on the basis of the input voltage U_in and the desired target value U_des for the output voltage of the DC voltage converter. In addition, the current in the DC voltage converter, in particular the current I_in at the input of the DC voltage converter module 50, can also be considered in order to determine the first regulating parameter R1. Furthermore, if necessary, the transformation ratio N of the transformer in the DC voltage converter module 50 can also be considered in order to determine the first regulating parameter R1.

[0022] In addition, a second regulating parameter R2 can be determined within a voltage regulation range by means of a second regulating device 20. The second regulating parameter R2 can be determined, in particular, taking into account the target value U_des for the output voltage of the DC voltage converter 1 and the actual current value U_out at the output of the DC voltage converter 1.

[0023] The first regulation parameter R1 from the first regulation device 10 and the second regulation parameter R2 from the second regulation device 20 can be combined, for example added up, in the combination device 40. The combination of the first regulation parameter R1 and the second regulation parameter R2 can be output as a target regulation parameter R3 by the combination device 40. Thus, this target regulation parameter R3 represents a regulation parameter which should be set taking into account the current output voltage U_out and further framework conditions such as, for example, the input voltage U_in, the input current I_in, etc. in order to achieve the desired output voltage U_des. The regulation parameter can, for example, be a specification of the duty cycle for controlling the switching elements in the DC voltage converter module 50.

[0024] Under specific operating conditions, in particular from a specific duty cycle onwards, too rapid a change in the regulation parameter, in particular a rapid change in the duty cycle, can lead to a rapid change in the current and thus to a high current gradient. In order to avoid damage to the components in the DC voltage converter 1, in particular in the DC voltage converter module 50, the change in the gradient of the regulation parameter R3 and thus the change in the current gradient, i.e. the change in the current in the DC voltage converter 1, can be limited by means of the third regulation device 30. If the gradient of the regulation parameter R3 of the combination device 40 exceeds a pre-given maximum value or the (negative) gradient of the regulation parameter R3 is below a minimum value, then the regulation parameter R3 output by the combination device 40 can be limited. In this way, the third regulation device 3 can provide an output regulation parameter R4, the gradient of which fluctuates within a pre-given window between a (positive) maximum value and a (negative) minimum value. Subsequently, this limited regulation parameter R4 can be provided to the DC voltage converter module 50.

[0025] The third regulation device 30 can, for example, calculate the current operating point R_cur from the current input voltage U_in, the transformation ratio N of the transformer in the DC voltage converter module 50 and the current output voltage U_out in the following way:

[0026] .

[0027] If the target regulation parameter R3 is significantly greater than the current operating point R_cur, this can lead to an excessive current in the DC voltage converter. Conversely, if the target regulation parameter R3 is significantly less than the current operating point R_cur, no current flows.

[0028] In order to avoid possible core saturation of the transformer in the DC voltage converter module 50, the gradient of the target adjustment parameter R3 can first be limited between a positive gradient d_up and a negative gradient d_down with the aid of a ramp function f().

[0029] In addition, the current gradient can be limited, for example, to a maximum of 10%:

[0030] 。

[0031] If 1.0 is added to this equation and the formula is used for the current operating point, then the following is obtained as a general condition between a low gradient d_min and a high gradient d_max:

[0032] 。

[0033] For this case, the gradient of the adjustment parameter for the DC voltage converter module 50 can be further limited to a maximum gradient d_slow with the aid of the ramp function f().

[0034] Figure 2 A schematic diagram of a block diagram of a third adjustment device 30 for limiting the gradient of the adjustment parameter for the DC voltage converter module 50 is shown, as previously described.

[0035] As can be seen in Figure 2 It is possible to limit the target adjustment parameter R3, for example, a combination of a first adjustment parameter R1 and a second adjustment parameter R2, in order to limit the gradient of the adjustment parameter R4 for controlling the DC voltage converter module 50. For this purpose, the current operating point can be determined from the input DC voltage U_in, the transformation ratio of the transformer in the DC voltage converter module 50, and the output DC voltage U_out. Subsequently, the current operating point can be limited according to the limits d_min, d_max and the predefined values for the maximum gradients d_up, d_down and d_slow. Subsequently, the adjustment parameter R4 limited in terms of its gradient can be output for controlling the DC voltage converter module 50.

[0036] Figure 3 A schematic diagram of a flowchart is shown as the basis for a method for operating a DC voltage converter 1 according to an embodiment.

[0037] In step S1, a first adjustment parameter is determined using the value of the current input voltage U_in, the value of the current input current I_in, and the target value for the output voltage U_des.

[0038] In step S2, a second adjustment parameter R2 is determined using the target value for the output voltage U_des and the value for the current output voltage U_out.

[0039] In step S3, the first adjustment parameter R1 and the second adjustment parameter R2 are combined into a target adjustment parameter R3.

[0040] In step S4, the gradient of the target adjustment parameter R4 is limited to a pre-determined maximum value and / or a pre-determined minimum value, and the target adjustment parameter R3 thus limited is provided as the output adjustment parameter R4.

[0041] Subsequently, the output adjustment parameter R4 limited in terms of gradient can be used to control one or more DC voltage converter modules 50 in step S5.

[0042] In summary, the present invention relates to the control of a DC voltage converter, wherein the gradient of the adjustment parameter used to control the DC voltage converter is limited. By limiting the gradient of the adjustment parameter, the maximum current change in the DC voltage converter can be limited in order to avoid dangerous operating states of the DC voltage converter if necessary.

Claims

1. A DC voltage converter (1), comprising: a first regulating device (10) designed to determine a first regulating parameter (R1) using the value of the current input voltage (U_in), the value of the current input current (I_in), and the target value for the output voltage (U_des); a second regulating device (20) designed to determine a second regulating parameter (R2) using the target value for the output voltage (U_des) and the value of the current output voltage (U_out); a combining device (40) designed to combine the first regulating parameter (R1) and the second regulating parameter (R2) and output a target regulating parameter (R3); a third regulating device (30) designed to limit the gradient of the target regulating parameter (R3) to a predetermined minimum value and / or a predetermined maximum value and provide the limited target regulating parameter (R3) as an output regulating parameter (R4); and at least one DC voltage converter module (50) designed to convert the input DC voltage (U_in) into an output DC voltage (U_out) using the output regulating parameter (R4).

2. The DC voltage converter (1) according to claim 1, wherein the third regulating device (30) is designed to limit the gradient of the target regulating parameter (R3) using the value of the current input voltage (U_in) and the value of the current output voltage (U_out).

3. The DC voltage converter (1) according to claim 1 or 2, wherein each of the at least one DC voltage converter module (50) includes a transformer, and the transformer is arranged between the input terminal and the output terminal, and wherein the third regulating device (30) is designed to limit the gradient of the target regulating parameter (R3) using the turns ratio (N) of the transformer.

4. The DC voltage converter (1) according to any one of claims 1 to 3, wherein the third regulating device (30) is designed to limit the maximum current change in the DC voltage converter (1).

5. The DC voltage converter (1) according to any one of claims 1 to 4, wherein the at least one DC voltage converter module (50) is operated in a boost chopper mode.

6. A method for operating a DC voltage converter (1), comprising the following steps: determining (S1) a first regulating parameter (R2) using the value of the current input voltage (U_in), the value of the current input current (I_in), and the target value for the output voltage (U_out); determining (S2) a second regulating parameter (R2) using the target value for the output voltage (U_des) and the value of the current output voltage (U_out); Combine the first adjustment parameter (R1) and the second adjustment parameter (R2) (S3) into a target adjustment parameter (R3); Limit (S4) the gradient of the target adjustment parameter (R3) to a predetermined minimum value and / or a predetermined maximum value, and provide the limited target adjustment parameter (R3) as an output adjustment parameter (R4); and Control (S5) a certain number of at least one DC voltage converter module (50) in the case of using the output adjustment parameter (R4).

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