Converter and method for matching actual conversion ratio to target conversion ratio - Patents.com

Abstract

There is shown and described a converter 1 for converting an input DC voltage into an output DC voltage, comprising a power unit 3 having a first converter stage 7 with two input terminals 13, a second converter stage 9 connected to the first converter stage 7 and a third converter stage 11 connected to the second converter stage 9 and with two output terminals 15, and a controller unit 5 coupled to the power unit 3, the first converter stage 7, the second converter stage 9 and the third converter stage 11 being configured to provide an output DC voltage at the two output terminals 15 when an input DC voltage is applied to the two input terminals 13 during operation of the converter 1, the actual conversion ratio of the power unit 3 being defined by the ratio between the input DC voltage applied to the two input terminals 13 and the output DC voltage applied to the two output terminals 15 or the ratio between the amount of input current occurring at the two input terminals 13 and the amount of output current occurring at the two output terminals 15, the controller unit 5 being configured to act on the power unit 3 to make the actual transformation ratio match a given target conversion ratio, and a corresponding method.

Description

[Technical field]

[0001] The present invention relates to a converter for converting an input DC voltage to an output DC voltage, comprising a power unit and a controller unit coupled to the power unit, as well as a method for converting an input DC voltage to an output DC voltage. [Background technology]

[0002] Converters with a power unit and a controller unit connected to the power unit are known from the prior art. For example, an input DC voltage can be applied to the power unit, which can be converted into an output DC voltage by means of switching elements of the power unit. For converting the input DC voltage into an output DC voltage, the switching elements are usually switched in phase with one another, each switching element being able to assume a conducting and an electrically insulating state, respectively. Furthermore, converters are known from the prior art, which for example comprise a power unit and can apply an input AC voltage which can be converted into an output AC voltage by means of the switching elements of the power unit. In that case too, the switching elements for converting the input AC voltage into an output AC voltage are usually switched in phase with one another, each switching element being able to assume a conducting and an electrically insulating state, respectively.

[0003] Converters capable of converting an input AC voltage into an output AC voltage, which may also be called AC / AC converters, are used, for example, in so-called AC power networks, to connect different voltage levels, such as extra-high and high, high and medium or medium and low voltage levels, to each other or to provide such voltage levels, which may also be called AC voltage levels. Converters capable of converting an input DC voltage into an output DC voltage, which may also be called DC / DC converters, are likewise used to connect different voltage levels to each other or to provide such voltage levels, which may also be called DC voltage levels. DC / DC converters known from the prior art usually operate as current or voltage sources.

[0004] When a DC / DC converter operates as a current source, the input DC voltage is controlled, i.e. held constant, and the converter creates a current source on the output or secondary side. When a DC / DC converter operates as a voltage source, the output DC voltage is controlled, i.e. held constant, and the converter creates a voltage source on the output or secondary side. When a converter operates as a current or voltage source, depending on the load flow direction, the power provided on the primary side, i.e. the input, is taken off on the secondary side, or the power provided on the secondary side is taken off on the primary side. Control technology models for controlling DC / DC converters, especially designed for converters as current or voltage sources, are known from the prior art. DC / DC converters often require a voltage regulation power network, which limits the flexibility with which DC / DC converters can be used. Furthermore, the voltage regulation operation of a DC / DC converter, i.e. when the converter provides a voltage source on the secondary side, can lead to a complex control of the converter.

[0005] In general, it is desirable to provide a DC / DC converter that is flexible in use and requires little complex control. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above, an object of the present invention is to provide a DC / DC converter that requires almost no complicated control and can be used flexibly.

[0007] In a first aspect of the invention, the problem is solved by a converter having the features of claim 1. The converter is realized to convert an input DC voltage into an output DC voltage. The converter comprises a power unit. The power unit comprises a first converter stage. The first converter stage comprises two input terminals. The power unit comprises a second converter stage connected to the first converter stage. Furthermore, the power unit comprises a third converter stage connected to the second converter stage. The third converter stage comprises two output terminals. The first converter stage, the second converter stage and the third converter stage are configured to provide an output DC voltage at the two output terminals when an input DC voltage is applied to the two input terminals during operation of the converter. The actual conversion ratio of the power unit is defined by the ratio of the input DC voltage applied to the two input terminals and the output DC voltage applied to the two output terminals or the ratio of the amount of input current occurring at the two input terminals and the amount of output current occurring at the two output terminals. Furthermore, the converter comprises a controller unit coupled to the power unit. The controller unit is configured to act on the power unit to cause the actual conversion ratio to match a given target conversion ratio.

[0008] The converter is realized to convert an input DC voltage into an output DC voltage. Both the input DC voltage and the output DC voltage are advantageously DC voltages whose instantaneous values ​​do not change over a longer observation period or change only slightly within a given DC voltage interval extending from a DC voltage minimum to a DC voltage maximum. When the instantaneous values ​​change over time, both the input DC voltage and the output DC voltage do not change their polarity.

[0009] The converter comprises a power unit, the power unit comprises a first converter stage, a second converter stage connected to the first converter stage, and a third converter stage connected to the second converter stage, the first converter stage, the second converter stage, and the third converter stage each constituting a part of the converter. In particular, the first converter stage, the second converter stage, and the third converter stage each comprise electronic components connected to each other such that each converter stage is capable of converting a corresponding converter stage input voltage applied to a corresponding input terminal to a corresponding converter stage output voltage applied to a corresponding output terminal. In particular, each converter stage is capable of converting a corresponding converter stage input voltage to a corresponding converter stage output voltage, such that the converter converts an input DC voltage to an output DC voltage. In particular, the input DC voltage corresponds to the converter stage input voltage of the first converter stage, and the output DC voltage corresponds to the converter stage output voltage of the third converter stage. In particular, the converter stage output voltage of the first converter stage, the converter stage input voltage of the second converter stage, the converter stage output voltage of the second converter stage and the converter stage input voltage of the third converter stage may each be an AC voltage. When referring to an AC voltage in the present invention, the instantaneous value of said AC voltage advantageously varies over a longer observation period. The instantaneous value of said AC voltage advantageously varies periodically. In particular, the instantaneous value of said AC voltage varies over time such that said AC voltage repeatedly changes its polarity over time. The converter according to the present invention can in particular be operated bidirectionally, i.e. independently of the load flow direction, so that the terms "input DC voltage", "output DC voltage", "converter stage input voltage" and "converter stage output voltage" should not be understood restrictively but rather denote the corresponding voltages with respect to the operating state of the converter when transferring energy from two input terminals to two output terminals.For the operating state of the converter when transmitting energy from two output terminals to two input terminals, the corresponding voltage expressions would have to be substituted, and in particular the expressions of the terminals, e.g. the input terminals and the output terminals, but this has been abandoned in order to facilitate the description of the components of this converter.

[0010] The first converter stage comprises two input terminals. The third converter stage comprises two output terminals. In particular, the two input terminals and the two output terminals each provide an electrical contact. The two input terminals can be connected to a voltage source, such that an electrical connection between the voltage source and the two input terminals is provided, such that an input DC voltage is applied to the two input terminals. The two output terminals can be connected to an electrical consumer, such that an electrical connection between the electrical consumer and the two output terminals is provided, such that a current can flow through the electrical consumer. In particular, the two input terminals can be connected to a first component of a DC power grid and the two output terminals can be connected to a second component of a DC power grid, the first component being associated with a first DC voltage level and the second component being associated with a second DC voltage level. When referring to two input terminals in the context of the present invention without explicitly indicating that the two input terminals are associated with a converter stage other than the first converter stage, the two input terminals refer to the two input terminals of the first converter stage. In connection with the present invention, when referring to two output terminals without explicitly indicating that the two output terminals correspond to a converter stage other than the third converter stage, those two output terminals refer to the two output terminals of the third converter stage.

[0011] The first, second and third converter stages are configured to provide an output DC voltage at two output terminals when an input DC voltage is applied to the two input terminals during converter operation. The first, second and third converter stages may each comprise one switching element or a number of switching elements. In particular, both the first and third converter stages each comprise a number of switching elements, in particular four switching elements each. Each switching element of the switching elements may comprise a transistor. Advantageously, the transistor is an insulated gate field effect transistor (IGFET), particularly advantageously a metal oxide semiconductor field effect transistor (MOSFET), more advantageously an insulated gate bipolar transistor (IGBT). Each transistor may be configured, for example, as an enhancement or depression type and may comprise an n-channel or a p-channel. Each switching element of the switching elements may comprise a diode. Each switching element of the switching elements in particular comprises a first terminal and a second terminal. Advantageously, the transistor of each switching element is connected to both the first terminal and the second terminal. Furthermore, the diode of each switching element is advantageously connected to both the first terminal and the second terminal. In particular, the transistor and the diode are connected in parallel with each other between the first terminal and the second terminal. In particular, each switching element of the switching elements can occupy a conducting state and an electrically insulating state. When a switching element is in a conducting state, a current can flow through the corresponding switching element. When the corresponding switching element is in an electrically insulating state, a current cannot flow through the corresponding switching element. Each switching element can be switched between the conducting state and the electrically insulating state by a corresponding switching process.

[0012] Advantageously, the switching elements of the first converter stage are connected to one another in a full-bridge arrangement, where two switching elements of the first converter stage are connected to a first of two input terminals, a first of these two switching elements is advantageously connected to a first output terminal of the first converter stage and a second of these two switching elements is advantageously connected to a second output terminal of the first converter stage, two further switching elements of the first converter stage are advantageously connected to a second of the two input terminals, a third of these two switching elements is advantageously connected to a first output terminal of the first converter stage and a fourth of these two switching elements is advantageously connected to a second output terminal of the first converter stage.

[0013] Advantageously, the switching elements of the third converter stage are connected to one another in a full-bridge arrangement. Two switching elements of the third converter stage are advantageously connected to a first output terminal. A first switching element of these two switching elements is advantageously connected to a first input terminal of the third converter stage, and a second switching element of these two switching elements is advantageously connected to a second input terminal of the third converter stage. Two further switching elements of the third converter stage are advantageously connected to a second output terminal. A third switching element of these two switching elements is advantageously connected to a first input terminal of the third converter stage, and a fourth switching element of these two switching elements is advantageously connected to a second input terminal of the third converter stage.

[0014] In particular, the second converter stage can comprise one inductance or multiple inductances. Advantageously, the second converter stage comprises two inductances forming a transformer. This transformer can form an intermediate frequency transformer. With this transformer, the second converter stage can provide electrical isolation, in particular between the first converter stage and the third converter stage. The two inductances of the transformer can comprise windings arranged in the same or opposite senses of the windings. That is to say, the transformer can comprise two windings with the same or opposite phase states. The second converter stage can further comprise a further inductance and a capacitance connected in series or parallel with the inductance, which together form a resonant circuit. With this resonant circuit, it can be ensured that the instantaneous value of the current when the switching element or elements pass from the conducting state to the electrically insulating state is particularly small, so that the power losses of the switching element or elements are particularly small and therefore the efficiency of the converter can be particularly high.

[0015] Furthermore, the actual conversion ratio of the power unit is defined by the ratio of the input DC voltage at the two input terminals to the output DC voltage at the two output terminals or the ratio of the amount of input current occurring at the two input terminals to the amount of output current occurring at the two output terminals. The converter preferably comprises a number of detection units. The number of detection units preferably comprises at least one first detection unit configured to detect a voltage. Furthermore, the number of detection units preferably comprises at least one second detection unit configured to detect a current. Advantageously, the first detection unit is connected to the two input terminals. Even more advantageously, the other first detection unit is connected to the two output terminals. Even more advantageously, the other first detection unit is connected to the two output terminals of the first converter stage and to the two input terminals of the second converter stage. Advantageously, the other first detection unit is connected to the two output terminals of the second converter stage and to the two input terminals of the third converter stage. Advantageously, the second detection unit is connected to one of the two input terminals. The other second detection unit is advantageously connected to one of the two output terminals. The further second detection unit is advantageously connected to one of the output terminals of the first converter stage and to one of the input terminals of the second converter stage. The further second detection unit is advantageously connected to one of the output terminals of the second converter stage and to one of the input terminals of the third converter stage. With the first detection unit connected to the two input terminals, an input DC voltage can be detected at these two input terminals. With the second detection unit connected to one of the two input terminals, an input current magnitude occurring at these two input terminals can be detected. In the context of the present invention, an input current magnitude occurring at the two input terminals means in particular that an input current magnitude occurs at least at the input terminal connected to the second detection unit. With the first detection unit connected to the two output terminals, an output DC voltage can be detected at these two output terminals.A second detection unit connected to one of the two output terminals can be used to detect the amount of output current occurring at these two output terminals. In the context of the present invention, an output current amount occurring at the two output terminals means in particular that an output current amount occurs at least at the output terminal connected to the second detection unit.

[0016] The main idea of ​​the present invention is to define a conversion ratio. This conversion ratio can be defined based on an input DC voltage applied to two input terminals and an output DC voltage applied to two output terminals. Alternatively, the conversion ratio can be defined based on a ratio between an amount of input current occurring at the two input terminals and an amount of output current occurring at the two output terminals. In particular, it is provided that the ratio between an amount of input DC voltage applied to the two input terminals and an amount of output DC voltage applied to the two output terminals or the ratio between an amount of input current occurring at the two input terminals and an amount of output current occurring at the two output terminals is defined. In particular, the input DC voltage and the output DC voltage detected by the first detection unit define the actual conversion ratio provided by the power unit at a time. Alternatively, the actual conversion ratio provided by the power unit at a time can be defined by an amount of input current and an amount of output current detected by the second detection unit. In particular, the actual conversion ratio is equal to either the quotient of the input DC voltage (dividend) and the output DC voltage (divisor) or the quotient of the amount of output current (dividend) and the amount of input current (divisor).

[0017] The converter further comprises a controller unit coupled to the power unit. In particular, the controller unit is connected to the switching elements for driving the switching elements. In particular, the controller unit can provide each switching element with a corresponding control signal, so that each switching element of the switching elements can be transferred from a corresponding conducting state to a corresponding electrically insulating state and from a corresponding electrically insulating state to a corresponding conducting state in response to the corresponding control signal. Furthermore, the controller unit is in particular connected to the first detection unit and the second detection unit. The controller unit can be provided with a corresponding detection signal from each first detection unit of the first detection units, which is equal to the actual value of the applied voltage. Furthermore, the controller unit can be provided with a corresponding detection signal from each second detection unit of the second detection units, which is equal to the amount of current produced. The controller unit can thus calculate the actual conversion ratio on the basis of these detection signals.

[0018] The controller unit is configured to act on the power unit to make the actual conversion ratio correspond to a given target conversion ratio. The controller unit can act on the power unit, in particular by driving switching elements. In particular, the conversion ratio to be achieved by the actual conversion ratio is called the target conversion ratio. This target conversion ratio can in particular be constant in time during a defined time period or can in particular be variable in time during a defined time period.

[0019] Advantageously, the actual conversion ratio is matched to a predefined target conversion ratio for a given range of voltages and / or a given range of current magnitudes. For example, for the first converter stage, the controller unit can act on the power unit to match the actual conversion ratio to the given target conversion ratio by defining a minimum and a maximum voltage between which the input DC voltage must lie. Furthermore, for example, for the first converter stage, the controller unit can act on the power unit to match the actual conversion ratio to the given target conversion ratio by defining a minimum and a maximum current between which the input current must lie. Furthermore, for example, for the third converter stage, the controller unit can act on the power unit to match the actual conversion ratio to the given target conversion ratio by defining a minimum and a maximum voltage between which the output voltage must lie. Furthermore, for example, for the third converter stage, the controller unit can act on the power unit to match the actual conversion ratio to the given target conversion ratio by defining a minimum and a maximum current between which the output current must lie. By matching the actual conversion ratio to a predefined target conversion ratio for a given range of voltages and / or a given range of current magnitudes, it can be ensured that the converter is reliably operable.

[0020] In summary, it can be seen that with the converter according to the invention, the actual conversion ratio is matched to a given target conversion ratio, thereby preventing the need to operate the converter as a current source or as a voltage source, as known from the prior art. The converter according to the invention does not require a voltage regulating power network. Furthermore, since the converter according to the invention does not provide a voltage source on the secondary side, the converter according to the invention does not require a complex control. The converter according to the invention can be used flexibly with little complex control. This is achieved in particular by defining an actual conversion ratio and a target conversion ratio and rarely matching the actual conversion ratio to the target conversion ratio. The flexibility of the use of the converter according to the invention is achieved in particular by the fact that it is not necessary to operate the converter as a current source or as a voltage source, thereby preventing the converter, in terms of its configuration and control, to a degree known from the prior art from components that directly interact with the converter, such as components of a power network, for example.

[0021] In one embodiment, the given target conversion ratio is constant in time. A time-constant target conversion ratio ensures that the converter according to the invention can be operated with a constant conversion ratio in a DC power network, similar to a transformer in an AC power network.

[0022] In one embodiment, the given target conversion ratio varies over time. This ensures that the converter according to the invention can be operated in a DC power grid with a varying conversion ratio, similar to a transformer in an AC power grid. The time-varying target conversion ratio allows the target conversion ratio to be adjusted in particular in the short term to external conditions, such as, for example, changes in the voltage applied to the input or output terminals or changes in the amount of current flowing through the input or output terminals.

[0023] In one embodiment, the first converter stage comprises an inverter electronic circuit. As already mentioned, the converter according to the invention can in particular be operated bidirectionally, so that the term "inverter" is not to be understood restrictively and only performs the function of an inverter with respect to the energy transfer from the input terminals to the output terminals. With respect to the energy transfer from the output terminals to the input terminals, the electronic circuit of the first converter stage performs the function of a rectifier. If the first converter stage comprises an inverter electronic circuit, a particularly simple electronic circuit is provided.

[0024] In one embodiment, the second converter stage is configured to provide electrical isolation. If the second converter stage is configured to provide electrical isolation, this is particularly advantageous when the input terminals are connected to a first power grid part and the output terminals are connected to a second power grid part, since the second converter stage ensures that the first and second power grid parts are electrically isolated from each other. The converter according to the invention therefore ensures an electrical isolation function, similar to that of a conventional transformer in an AC power grid.

[0025] In one embodiment, the second converter stage comprises a transformer. If the second converter stage comprises a transformer, a particularly simple construction of the electronic circuitry of the second converter stage is provided.

[0026] In one embodiment, the second converter stage comprises a voltage converter electronic circuit. If the second converter stage comprises a voltage converter electronic circuit, a particularly simple electronic circuit as a transformer replacement is provided.

[0027] In one embodiment, the third converter stage comprises a rectifier electronic circuit. As already mentioned, the converter according to the invention can in particular be operated bidirectionally, so that the term "rectifier" should not be understood restrictively and in fact only performs the function of a rectifier with respect to the energy transfer from the input terminals to the output terminals. With respect to the energy transfer from the output terminals to the input terminals, the electronic circuit of the third converter stage performs the function of an inverter. If the third converter stage comprises a rectifier electronic circuit, a particularly simple electronic circuit is provided.

[0028] In one embodiment, the converter comprises a first energy store connected to two input terminals. When a voltage source is connected to the two input terminals, the voltage source can provide charged particles to the first energy store, so that energy can be temporarily stored in the first energy store. When the converter requires a large amount of energy for a short time, the charged particles stored in the first energy store are released from the store, so that sufficient charged particles can be provided for a large energy demand for a short time. The first energy store can comprise at least one capacitance. The at least one capacitance can electrostatically store charged particles, so that the charged particles can be released in a particularly short time.

[0029] In one embodiment, the converter comprises a second energy store connected to two output terminals. When an electrical consumer is connected to these two output terminals, the converter can provide the second energy store with charged particles, so that energy can be temporarily stored in the second energy store. When the electrical consumer requires a large amount of energy for a short time, the charged particles stored in the second energy store can be released from said store, so that sufficient charged particles can be provided for a large energy demand for a short time. The second energy store can comprise at least one capacitance. The at least one capacitance can store the charged particles electrostatically, so that the charged particles can be released in a particularly short time.

[0030] In one embodiment, the controller unit comprises a first pilot control unit, which is configured to adjust the control variable provided by the controller unit taking into account the detected first actual value, so that the actual conversion ratio corresponds to a given target conversion ratio. The control variable provided by the controller unit can also be called the first control variable. The first control variable is defined so that the actual conversion ratio corresponds to a given target conversion ratio. The first pilot control unit is configured to adjust the control variable taking into account the detected first actual value. The detected first actual value can be, for example, an input DC voltage at the two input terminals, an output DC voltage at the two output terminals, an input current amount occurring at the two input terminals or an output current amount occurring at the two output terminals. The detected first actual value is particularly preferably an output current amount occurring at the two output terminals. The first pilot control unit ensures that the power unit can be operated at a suitable operating point, for example, depending on a load current, which can be defined by a load state.

[0031] In one embodiment, the controller unit comprises an adjustment unit configured to adjust a given target conversion ratio, so that the controller unit acts on the power unit to make the detected second actual value correspond to a given first setpoint value. The adjustment unit is configured to adjust the given target conversion ratio. The given target conversion ratio is adjusted by the adjustment unit, so that the controller unit acts on the power unit to make the detected second actual value correspond to the given first setpoint value. The detected second actual value can be, for example, an input DC voltage applied to the two input terminals, an output DC voltage applied to the two output terminals, an input current amount occurring at the two input terminals or an output current amount occurring at the two output terminals. Particularly preferably, the detected second actual value is an output DC voltage applied to the two output terminals. With the adjustment unit, the input DC voltage applied to the two input terminals, the output DC voltage applied to the two output terminals, the input current occurring at the two input terminals or the output current occurring at the two output terminals can be optimized.

[0032] In one embodiment, the controller unit comprises a second pilot control unit, which is configured to adjust the control variable provided by the adjustment unit in consideration of the detected third actual value so that the second actual value corresponds to a given first setpoint value. The control variable provided by the adjustment unit can also be called the second control variable. The second control variable is defined in order to match the second actual value to a given first setpoint value. The second pilot control unit is configured to adjust the second control variable in consideration of the detected third actual value. The detected third actual value can be, for example, an input DC voltage at the two input terminals, an output DC voltage at the two output terminals, an input current amount occurring at the two input terminals or an output current amount occurring at the two output terminals. Particularly preferably, the detected third actual value is an input current amount occurring at the two input terminals. The second pilot control unit ensures that the operating point at which the power unit operates can be optimized.

[0033] In one embodiment, the first setpoint value is defined by a characteristic curve or a family of characteristic curves. By defining the first setpoint value by a characteristic curve or a family of characteristic curves, additional control and / or protection functions can be realized.

[0034] In a second aspect of the invention, the problem stated at the outset is solved by a method having the features of claim 15. The method is defined for converting an input DC voltage into an output DC voltage using a converter according to the first aspect of the invention. The method comprises the steps of applying an input DC voltage to two input terminals of a first converter stage of the power unit, providing an output DC voltage to two output terminals of a third converter stage of the power unit, detecting the input DC voltage and the output DC voltage or detecting the amount of input current at the two input terminals and the amount of output current at the two output terminals, and acting on the power unit by means of a controller unit to match the actual conversion ratio to a given target conversion ratio. The features, technical effects and / or advantages mentioned in connection with the converter according to the first aspect of the invention at least equally apply to the method according to the second aspect of the invention, so that the corresponding repetition here is omitted.

[0035] Further features, advantages and applicability of the invention will become apparent from the following description of the embodiments and the drawings, in which all the features described and / or illustrated in the drawings, either alone or in any combination, constitute the subject matter of the invention, regardless of their incorporation or reference in the individual claims. Moreover, in the drawings, the same reference numerals represent the same or similar objects. [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 shows a schematic diagram of one embodiment of a converter according to the invention with a power unit and a controller unit. [Diagram 2] FIG. 1 is a schematic diagram of a first embodiment of a controller unit of a converter according to the invention; [Diagram 3]FIG. 2 is a schematic diagram of a second embodiment of the controller unit of the converter according to the invention; [Figure 4] FIG. 3 is a schematic diagram of a third embodiment of the controller unit of the converter according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Figure 1 shows a schematic diagram of one embodiment of a converter 1 according to the invention with a power unit 3 and a controller unit 5. Figure 2 shows a schematic diagram of a first embodiment of the controller unit 5 of the converter 1 according to the invention, Figure 3 shows a schematic diagram of a second embodiment of the controller unit 5 of the converter 1 according to the invention and Figure 4 shows a schematic diagram of a third embodiment of the controller unit 5 of the converter 1 according to the invention. Figures 2, 3 and 4 each likewise show the power unit 3 in a schematic diagram.

[0038] The converter 1 comprises a power unit 3 and a controller unit 5 coupled to the power unit 3. The power unit 3 comprises a first converter stage 7, a second converter stage 9 and a third converter stage 11. The first converter stage 7 is connected to the second converter stage 9, which is further connected to the third converter stage 11. The first converter stage 7 comprises two input terminals 13. The third converter stage 11 comprises two output terminals 15. The converter 1 further comprises a first energy store 17 connected to the two input terminals 13. The converter 1 further comprises a second energy store 19 connected to the two output terminals 15.

[0039] The converter 1 comprises a number of detection units. The number of detection units comprises a first detection unit 21, each configured to detect a voltage, and a second detection unit 23, each configured to detect a current amount. One first detection unit 21 is connected to two input terminals 13. Another first detection unit 21 is connected to two output terminals 15. Another first detection unit 21 is connected to two output terminals of the first converter stage 7, which are not explicitly shown in FIG. 1, and to two input terminals of the second converter stage 9, which are not explicitly shown in FIG. 1. Another first detection unit 21 is connected to two output terminals of the second converter stage 9, which are not explicitly shown in FIG. 1, and to two input terminals of the third converter stage 11, which are not explicitly shown in FIG. 1. One second detection unit 23 is connected to one of the two input terminals 13. Another second detection unit 23 is connected to one of the two output terminals 15. Another second detection unit 23 is connected to one of two output terminals not explicitly shown in FIG. 1 of the first converter stage 7 and to one of two input terminals not explicitly shown in FIG. 1 of the second converter stage 9. Another second detection unit 23 is connected to one of two output terminals not explicitly shown in FIG. 1 of the second converter stage 9 and to one of two input terminals not explicitly shown in FIG. 1 of the third converter stage 11. The converter 1 shown in FIG. 1 can in particular be operated bidirectionally, i.e. independently of the load flow direction, so that the terms "input terminal" and "output terminal" should not be understood in a restrictive manner and in fact only constitute "input terminal" or "output terminal" with respect to the energy transmission from left to right in FIG. 1.For energy transmission from right to left in Figure 1, similarly, each input terminal (for energy transmission from left to right in Figure 1) constitutes an output terminal (for energy transmission from right to left in Figure 1), and each output terminal (for energy transmission from left to right in Figure 1) constitutes an input terminal (for energy transmission from right to left in Figure 1).

[0040] The first converter stage 7 comprises four switching elements 25. The third converter stage 11 comprises four switching elements 25. Each switching element 25 of both the first converter stage 7 and the third converter stage 11 comprises a transistor 27, preferably an insulated gate field effect transistor (IGFET), particularly preferably a metal oxide semiconductor field effect transistor (MOSFET), and a diode 29. Particularly preferably, each transistor 27 is a bipolar transistor with insulated gate electrode (IGBT). Bipolar transistors with insulated gate electrodes provide good forward operation, high reverse voltage, high robustness and operation with low power demand. The transistor 27 and the diode 29 of each switching element 25 are respectively connected to the first and second terminals of the corresponding switching element 25, and these transistors 27 and diodes 29 are connected in parallel with each other between the first and second terminals. Each transistor 27 can be configured as an enhancement or depletion type and can comprise an n-channel or a p-channel, for example. Each of these switching elements 25 can occupy a conducting state and an electrically insulating state. When a switching element 25 is in a conducting state, current can flow through the corresponding switching element 25. When the corresponding switching element 25 is in an electrically insulating state, current cannot flow through the corresponding switching element. Each switching element 25 can be switched between the conducting state and the electrically insulating state by a corresponding switching process.

[0041] The first converter stage 7 comprises an electronic circuit of an inverter. As already mentioned, the converter 1 shown in FIG. 1 can in particular be operated bidirectionally, so that the term "inverter" should not be understood restrictively and in fact only performs the function of an inverter with respect to the energy transfer from left to right in FIG. 1. With respect to the energy transfer from right to left in FIG. 1, the electronic circuit of the first converter stage 7 performs the function of a rectifier. The switching elements 25 of the first converter stage 7 are connected to one another in a full-bridge arrangement. Two switching elements 25 of the first converter stage 7 are connected to a first input terminal 13. A first switching element 25 of these two switching elements 25 is connected to a first output terminal of the first converter stage 7, which is not explicitly shown in FIG. 1, and a second switching element 25 of these two switching elements 25 is connected to a second output terminal of the first converter stage 7, which is not explicitly shown in FIG. 1. Two further switching elements 25 of the first converter stage 7 are connected to a second input terminal 13. The third switching element 25 of these two switching elements 25 is connected to a first output terminal of the first converter stage 7, and the fourth switching element 25 of these two switching elements 25 is connected to a second output terminal of the first converter stage 7.

[0042] The third converter stage 11 comprises an electronic circuit of a rectifier. As already mentioned, the converter 1 shown in FIG. 1 can in particular be operated bidirectionally, so that the term "rectifier" should not be understood restrictively and in fact only performs the function of a rectifier with respect to the energy transfer from left to right in FIG. 1. With respect to the energy transfer from right to left in FIG. 1, the electronic circuit of the third converter stage 11 performs the function of an inverter. The switching elements 25 of the third converter stage 11 are connected to one another in a full-bridge arrangement. Two switching elements 25 of the third converter stage 11 are connected to a first output terminal 15. A first switching element 25 of these two switching elements 25 is connected to a first input terminal of the third converter stage 11, which is not explicitly shown in FIG. 1, and a second switching element 25 of these two switching elements 25 is connected to a second input terminal of the third converter stage 11, which is not explicitly shown in FIG. 1. Two further switching elements 25 of the third converter stage 11 are connected to a second output terminal 15. The third switching element 25 of these two switching elements 25 is connected to a first input terminal of the third converter stage 11, and the fourth switching element 25 of these two switching elements 25 is connected to a second input terminal of the third converter stage 11.

[0043] The second converter stage 9 comprises three inductances 31, two of which form a transformer, i.e. the second converter stage 9 comprises a transformer which in this embodiment is configured as an intermediate frequency transformer. With this transformer, the second converter stage 9 can in particular provide electrical isolation between the first converter stage 7 and the third converter stage 11. The two inductances 31 of the transformer have windings arranged in the same direction, i.e. the transformer has two windings in the same phase state. In addition to the inductance 31 which is not part of the transformer, a capacitance can be arranged in series with it, in which case the inductance 31 and the capacitance form a series resonant circuit. With this series resonant circuit, it can be ensured that the instantaneous value of the current when the switching element or elements 25 pass from the conducting state to the electrically insulating state is particularly small, so that the power losses of the switching element or elements 25 are particularly small and therefore the efficiency of the converter 1 can be particularly increased. Instead of the two inductances 31 forming this transformer, the second converter stage 9 can also comprise the electronic circuitry of a voltage converter.

[0044] The converter 1 is configured to convert an input DC voltage into an output DC voltage. The input DC voltage can be applied to two input terminals 13. The output DC voltage can be provided at two output terminals 15. The first converter stage 7, the second converter stage 9 and the third converter stage 11 are configured to provide an output DC voltage at the two output terminals 15 when an input DC voltage is applied to the two input terminals 13 during operation of the converter 1.

[0045] A first detection unit 21 connected to the two input terminals 13 can be used to detect an input DC voltage applied to the two input terminals 13. A second detection unit 23 connected to one of the two input terminals 13 can be used to detect an input current amount occurring at the two input terminals 13. In the context of the present invention, the input current amount occurring at the two input terminals 13 particularly means that the input current amount occurs at least at the input terminal 13 to which the second detection unit 23 is connected.

[0046] A first detection unit 21 connected to the two output terminals 15 can be used to detect the output DC voltage applied to these two output terminals 15. A second detection unit 23 connected to one of the two output terminals 15 can be used to detect the amount of output current generated at these two output terminals 15. In the context of the present invention, an amount of output current generated at the two output terminals 15 particularly means that an amount of output current is generated at least at the output terminal 15 to which the second detection unit 23 is connected.

[0047] The main idea of ​​the present invention is to define a conversion ratio. This conversion ratio can be defined based on the input DC voltage applied to the two input terminals 13 and the output DC voltage applied to the two output terminals 15. Alternatively, this conversion ratio can be defined based on the input currents occurring at the two input terminals 13 and the output currents occurring at the two output terminals 15. In particular, it is provided to define either the ratio of the input DC voltages occurring at the two input terminals 13 and the output DC voltages occurring at the two output terminals 15 or the ratio of the input currents occurring at the two input terminals 13 and the output currents occurring at the two output terminals 15. The input DC voltages and the output DC voltages detected by the first detection unit 21 define the actual conversion ratio provided by the power unit 3 at a single time. Alternatively, the actual conversion ratio provided by the power unit 3 at a single time can be defined by the input currents and the output currents detected by the second detection unit 21. In particular, the actual conversion ratio of the power unit 3 is defined by the ratio of the input DC voltage applied to the two input terminals 13 to the output DC voltage applied to the two output terminals 15, or the ratio of the amount of input current occurring at the two input terminals 13 to the amount of output current occurring at the two output terminals 15. In particular, the actual conversion ratio is equal to either the quotient of the input DC voltage (dividend) and the output DC voltage (divisor), or the quotient of the amount of output current (dividend) and the amount of input current (divisor).

[0048] As already mentioned, the controller unit 5 is coupled to the power unit 3. In particular, the controller unit 5 is connected to the switching elements 25 in order to drive the switching elements 25. In particular, the controller unit 5 can provide each switching element 25 with a corresponding control signal, so that each switching element 25 of the switching elements 25 can be transferred from a corresponding conducting state to a corresponding electrically insulating state and from a corresponding electrically insulating state to a corresponding conducting state in response to the corresponding control signal. The controller unit 5 can act on the power unit 3 by driving the switching elements 25. Furthermore, the controller unit 5 is in particular connected to the first detection unit 21 and the second detection unit 23. The controller unit 5 can be provided with a corresponding detection signal from each first detection unit 21 of the first detection unit 21, which is equal to the actual value of the applied voltage. Furthermore, the controller unit 5 can be provided with a corresponding detection signal from each second detection unit 23 of the second detection unit 23, which is equal to the actual value of the generated current amount. In other words, the controller unit 5 can calculate the actual conversion ratio based on the detection signals. The conversion ratio to be achieved by the actual conversion ratio is called the target conversion ratio. This target conversion ratio can in particular be constant in time for a defined time period or can in particular be variable in time for a defined time period. The controller unit 5 is configured to act on the power unit 3 to make the actual conversion ratio correspond to a given target conversion ratio.

[0049] In particular, it is provided that the actual conversion ratio is matched to a given target conversion ratio for a given range of voltages and / or a given range of current magnitudes. In order for the controller unit 5 to act on the power unit 3 in order to match the actual conversion ratio to a given target conversion ratio, it can for example define for the first converter stage 7 a minimum and a maximum voltage between which the input DC voltage must be. Furthermore, in order for the controller unit 5 to act on the power unit 3 in order to match the actual conversion ratio to a given target conversion ratio, it can for example define for the first converter stage 7 a minimum and a maximum current between which the input current must be. Furthermore, in order for the controller unit 5 to act on the power unit 3 in order to match the actual conversion ratio to a given target conversion ratio, it can for example define for the third converter stage 11 a minimum and a maximum voltage between which the output DC voltage must be. Furthermore, for the third converter stage 11, a minimum and a maximum current magnitude can be defined, between which the output current magnitude must lie, in order for this controller unit 5 to act on the power unit 3 to match the actual conversion ratio to a given target conversion ratio. By matching the actual conversion ratio to a given target conversion ratio for a given range of voltages and / or a given range of current magnitudes, it can be ensured that the converter 1 is reliably operable.

[0050] As already mentioned, FIG. 2 illustrates a schematic diagram of a first implementation configuration of the controller unit 5 of the converter 1 according to the present invention, FIG. 3 illustrates a schematic diagram of a second implementation configuration of the controller unit 5 of the converter 1 according to the present invention, and FIG. 4 illustrates a schematic diagram of a third implementation configuration of the controller unit 5 of the converter 1 according to the present invention.

[0051] The first embodiment of the controller unit 5 of FIG. 2 comprises a first pilot control unit 33. This first pilot control unit 33 is configured to adjust a control variable 35, which may also be called a first control variable, provided by the controller unit 5. This control variable 35 is defined in order to adjust an actual conversion ratio, designated by reference 37 in FIGS. 2, 3 and 4, to a given target conversion ratio, designated by reference 39 in FIGS. 2, 3 and 4. The first pilot control unit 33 is configured to adjust the control variable 35 taking into account a detected first actual value 41. This detected first actual value 41 can be, for example, an input DC voltage at the two input terminals 13, an output DC voltage at the two output terminals 15, an input current amount occurring at the two input terminals 13 or an output current amount occurring at the two output terminals 15. Particularly preferably, this detected first actual value 41 is an output current amount occurring at the two output terminals 15. The first pilot control unit 33 ensures that the power unit 3 can operate at a suitable operating point depending on the load current, which can be defined by the load condition, for example.

[0052] The second embodiment of the controller unit 5 of Fig. 3 further comprises an adjustment unit 43, which is configured to adjust a given target conversion ratio 39. The given target conversion ratio 39 is adjusted by the adjustment unit 43, such that the controller unit 5 acts on the power unit 3 to make the detected second actual value 45 correspond to a given first target value 47. That is to say, the adjustment unit 43 is configured to adjust the given target conversion ratio, such that the controller unit 5 acts on the power unit 3 to make the detected second actual value 45 correspond to the given first target value 47. The detected second actual value 45 can be, for example, an input DC voltage at the two input terminals 13, an output DC voltage at the two output terminals 15, an input current amount occurring at the two input terminals 13 or an output current amount occurring at the two output terminals 15. Particularly preferably, the detected second actual value 45 is an output DC voltage at the two output terminals 15. Using this adjustment unit 43, the input DC voltage applied to the two input terminals 13, the output DC voltage applied to the two output terminals 15, the amount of input current occurring at the two input terminals 13, or the amount of output current occurring at the two output terminals 15 can be optimized.

[0053] Furthermore, the second embodiment of the controller unit 5 of FIG. 3 further comprises a second pilot control unit 49. This second pilot control unit 49 is configured to adjust a control variable 51, which can also be called a second control variable, provided by the adjustment unit 43. This control variable 51 is defined in order to make the second actual value 45 correspond to a given first setpoint value 47. The second pilot control unit 49 is configured to adjust the control variable 51 taking into account a detected third actual value 53. This detected third actual value 53 can be, for example, an input DC voltage at the two input terminals 13, an output DC voltage at the two output terminals 15, an input current magnitude occurring at the two input terminals 13 or an output current magnitude occurring at the two output terminals 15. Particularly preferably, this detected third actual value 53 is an input current magnitude occurring at the two input terminals. The second pilot control unit 49 ensures that the operating point at which the power unit 3 operates can be further optimized.

[0054] A third embodiment of the controller unit 5 of the converter 1 according to the invention, which is shown diagrammatically in FIG. 4, is essentially the same as the second embodiment of the controller unit 5, which is shown diagrammatically in FIG. 3, except that in the second embodiment the given first setpoint value 47 is a given constant value, and in the third embodiment the given first setpoint value 47 is defined by a characteristic curve or a family of characteristic curves. If the given first setpoint value 47 is a given constant value, a solution with a particularly low computational effort is provided. If the given first setpoint value 47 is defined by a characteristic curve or a family of characteristic curves, a protection function can be provided, for example, in particular if a correspondence is provided between the characteristic curve or family of characteristic curves and the input DC voltage applied to the two input terminals 13, the output DC voltage applied to the two output terminals 15, the amount of input current occurring at the two input terminals 13 and / or the amount of output current occurring at the two output terminals 15.

[0055] A method for converting an input DC voltage into an output DC voltage can be implemented with the converter 1 according to the invention. As already mentioned at least as well when describing the operating mode of the converter 1 according to the invention, the method can comprise the steps of applying an input DC voltage to the two input terminals 13 of the first converter stage 7 of the power unit 3, providing an output DC voltage to the two output terminals 15 of the third converter stage 11 of the power unit 3, detecting the input DC voltage and the output DC voltage or detecting the amount of input current at the two input terminals 13 and the amount of output current at the two output terminals 15, and acting on the power unit 3 by means of the controller unit 5 in order to match the actual conversion ratio to a given target conversion ratio.

[0056] Additionally, it should be noted that "comprising" does not exclude other elements or steps, and "a" does not exclude a plurality. Furthermore, it should be noted that a feature described with reference to one of the above embodiments can also be used in combination with another feature of another embodiment described above. The reference signs in the claims should not be considered as limiting the invention. [Explanation of symbols]

[0057] 1 Converter 3. Power unit 5 Controller unit 7 First Converter Stage 9 Second Converter Stage 11 Third Converter Stage 13 Input terminal 15 Output terminal 17 First Energy Storage 19 Second Energy Storage 21 First detection unit 23 Second detection unit 25 Switching elements 27 Transistor 29 Diode 31 Inductance 33 First Pilot Control Unit 35 First control variable 37 Actual conversion ratio 39 Target Conversion Ratio 41 First actual value detected 43 Adjustment unit 45 Second actual value detected 47 Given first target value 49 Second Pilot Control Unit 51 Second control variable 53 Third actual value detected

Claims

1. A converter (1) for converting an input DC voltage into an output DC voltage, comprising a power unit (3) having a first converter stage (7) with two input terminals (13), a second converter stage (9) connected to the first converter stage (7), and a third converter stage (11) connected to the second converter stage (9) and having two output terminals (15), and a controller unit (5) coupled to the power unit (3), wherein the first converter stage (7), the second converter stage (9), and the third converter stage (11) are configured to provide an output DC voltage at the two output terminals (15) when an input DC voltage is applied to the two input terminals (13) during operation of the converter (1), and the actual conversion ratio of the power unit (3) is defined by the ratio of the input DC voltage applied to the two input terminals (13) to the output DC voltage applied to the two output terminals (15) or the ratio of the input current amount generated at the two input terminals (13) to the output current amount generated at the two output terminals (15), and the controller unit (5) is configured to act on the power unit (3) to match the actual transformation ratio to a given target transformation ratio. Converter.

2. The converter (1) according to claim 1, wherein the given target conversion ratio is constant over time.

3. The converter (1) according to claim 1, wherein the given target conversion ratio is variable over time.

4. The converter (1) according to any one of claims 1 to 3, wherein the first converter stage (7) comprises an electronic circuit of an inverter.

5. The converter (1) according to any one of claims 1 to 3, wherein the second converter stage (9) is configured to provide an electrical insulation part.

6. The converter (1) according to claim 5, wherein the second converter stage (9) comprises a transformer.

7. The converter (1) according to any one of claims 1 to 3, wherein the second converter stage (9) comprises an electronic circuit of a voltage converter.

8. The converter (1) according to any one of claims 1 to 3, wherein the third converter stage (11) comprises an electronic circuit of a rectifier.

9. The converter (1) according to any one of claims 1 to 3, A converter further comprising a first energy storage device (17) connected to the two input terminals (13) described above.

10. In the converter (1) according to any one of claims 1 to 3, A converter further comprising a second energy storage device (19) connected to the two output terminals (15) described above.

11. In the converter (1) according to any one of claims 1 to 3, The controller unit (5) described above includes a first pilot control unit (33), and this first pilot control unit is configured to adjust a control variable (35) provided from the controller unit (5) in order to match the actual conversion ratio with a given target conversion ratio in consideration of the detected first actual value (41). A converter configured as such.

12. In the converter (1) according to any one of claims 1 to 3, The controller unit (5) described above includes an adjustment unit (43), and this controller unit (5) acts on the power unit (3) so that the detected second actual value (45) matches a given first target value (47). A converter configured such that this adjustment unit adjusts a given target conversion ratio.

13. In the converter (1) according to claim 12, The controller unit (5) described above includes a second pilot control unit (49), and this second pilot control unit is configured to adjust a control variable (51) provided from the adjustment unit (43) in order to match the second actual value (45) with a given first target value (47) in consideration of the detected third actual value (53). A converter configured as such.

14. In the converter (1) according to claim 12, A converter in which the first target value (47) is defined by a characteristic curve or a group of characteristic curves.

15. A method for converting an input DC voltage into an output DC voltage using the converter (1) according to any one of claims 1 to 3, comprising: Applying an input DC voltage to two input terminals (13) of a first converter stage (7) of the power unit (3); Providing an output DC voltage to two output terminals (15) of a third converter stage (11) of the power unit (3); Detecting the input DC voltage and the output DC voltage, or detecting the input current amount at the two input terminals (13) and the output current amount at the two output terminals (15). A step of the controller unit (5) acting on the power unit (3) so that the actual transformation ratio matches a given target transformation ratio, A method having the above.

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