Dc-dc converter

Abstract

Proposed is a DC-DC converter (100) comprising: a transformer (1); an input circuit (2) that is configured to receive an input DC voltage (Ueg) and to provide an input AC voltage (Uew) to the transformer (1); and an output circuit (3) that is configured to receive an output AC voltage (Uaw) from the transformer (1) and to provide an output DC voltage (Uag), wherein a leakage inductance estimating device (4) is provided which is configured to determine and / or to receive operating parameters (P-De, P-T, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag) of the input circuit (2) and of the output circuit (3) and, on the basis of the operating parameters (P-De, P-T, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag), to determine a leakage inductance parameter (P-L) that estimates a leakage inductance of the transformer (1).

Description

[0001] DC-DC converter

[0002] Description

[0003] The present invention relates to a DC-DC converter comprising: a transformer, an input circuit configured to receive an input DC voltage and to provide an input AC voltage to the transformer, and an output circuit configured to receive an output AC voltage from the transformer and to provide an output DC voltage.

[0004] Such DC-DC converters are known from the prior art, with the transformer providing galvanic isolation between the input and output circuits. Due to manufacturing limitations, transformers and transformer circuits generally exhibit a relatively large tolerance with regard to their leakage inductance. The term "leakage inductance" encompasses all inductances electrically connected in series with an input winding of the transformer that generate a magnetic flux that does not flow through an output winding of the transformer, such as line inductances or inductances provided as discrete components connected in series with the input winding of the transformer.Since, in particular, the upper power limit of the DC-DC converter is strongly influenced by the actual leakage inductance of the transformer, the actual leakage inductance of the transformer is typically determined by relatively complex measurements and the DC-DC converter is calibrated based on the measured leakage inductance of the transformer.

[0005] Against this background, the task is to create a DC-DC converter that is relatively easy to calibrate.

[0006] This object is achieved according to the invention by a DC-DC converter having the features of claim 1. The DC-DC converter according to the invention comprises a transformer, i.e., a component with at least one input winding and at least one output winding, which are magnetically coupled such that, when an AC input voltage is applied to the at least one input winding, an AC output voltage is induced in the at least one output winding. The ratio between the AC input voltage and the AC output voltage can be determined, in particular, via the number of turns of the at least one input winding and the at least one output winding.

[0007] The DC-DC converter according to the invention further comprises an input circuit configured to receive, i.e., provide, an input DC voltage from a DC voltage source or an upstream circuit, and to provide an input AC voltage to the transformer, specifically to the at least one input winding of the transformer. The input circuit thus comprises an inverter device that converts the input DC voltage into the input AC voltage. The inverter device can, in principle, be designed in any manner known from the prior art.

[0008] The DC-DC converter according to the invention further comprises an output circuit configured to receive an AC output voltage from the transformer, specifically from the at least one output winding of the transformer, i.e., to be provided by the transformer, and to provide a DC output voltage to a load or a downstream circuit. The output circuit thus comprises a rectifier device that converts the AC output voltage into the DC output voltage. The rectifier device can, in principle, be configured in any manner known from the prior art.

[0009] According to the invention, the DC-DC converter further comprises a leakage inductance estimator configured to determine and / or receive operating parameters of the input circuit and the output circuit. The leakage inductance estimator can be connected, for example, to the input circuit and / or the output circuit via a suitable electrical connection in order to use one or more measuring devices to metrologically determine one or more electrical parameters of the input circuit and / or the output circuit, which parameters can, for example, indicate an electrical voltage or an electrical current of the input circuit or the output circuit, respectively.Alternatively or additionally, the leakage inductance estimation device can also be connected to the input circuit and / or the output circuit, for example via a data line, in order to read out or receive an operating parameter from the input circuit or the output circuit in digital form, for example from a control device or a monitoring device of the input circuit or the output circuit.

[0010] According to the invention, the leakage inductance estimation device is further configured to determine a leakage inductance parameter based on the operating parameters of the input circuit and the output circuit, which parameter estimates the leakage inductance of the transformer. This enables a relatively simple calibration of the DC-DC converter according to the invention, since no special, relatively complex measurements need to be performed to determine or estimate the leakage inductance of the transformer.

[0011] Preferably, the leakage inductance estimation device comprises a computing unit to which the operating parameters are provided and which is configured to calculate the leakage inductance parameter based on the operating parameters using a stored algorithm. This enables a relatively simple determination of the leakage inductance parameter. Preferably, the algorithm stored in the computing unit is essentially based on a single mathematical formula encompassing all of the provided operating parameters. The computing unit can be implemented, for example, by a microcontroller or a correspondingly designed ASIC.In a preferred embodiment, the input circuit and / or the output circuit comprises a plurality of semiconductor switches that are interconnected in a known manner in the form of a bridge circuit, wherein at least one control device is provided that is configured to provide periodic control signals to the semiconductor switches of the input circuit and / or to the semiconductor switches of the output circuit for controlling the semiconductor switches. This allows a simple conversion of the input DC voltage into the input AC voltage and / or a simple conversion of the output AC voltage into the output DC voltage in the input circuit.It is expressly pointed out that the term "control device" within the meaning of the present invention refers to both a control device (open path of action) and a control device (closed path of action). The "control device," technically correctly referred to, can therefore also be a control device. Preferably, both the input circuit and the output circuit each comprise a plurality of semiconductor switches connected in the form of a bridge circuit, with the semiconductor switches of the input circuit and the semiconductor switches of the output circuit typically being provided with different periodic control signals, in particular those having different duty cycles.It is conceivable that the semiconductor switches of the input circuit and the semiconductor switches of the output circuit are controlled by a single control device, as well as that the input circuit and the output circuit each have their own control device for controlling the respective semiconductor switches.

[0012] Preferably, the operating parameters present in the leakage inductance estimator include at least one duty cycle parameter that indicates a duty cycle of a periodic control signal provided by the control device to the semiconductor switches of the input circuit or to the semiconductor switches of the output circuit. The duty cycle parameter of the leakage inductance estimator is preferably provided by the control device. However, it is also conceivable for the leakage inductance estimator to be configured to determine the duty cycle parameter by measurement.In the case where both the input circuit and the output circuit each comprise semiconductor switches, the operating parameters preferably comprise two duty cycle parameters, one of which specifies the duty cycle of the periodic control signals provided to the semiconductor switches of the input circuit, and the other of which specifies the duty cycle of the periodic control signals provided to the semiconductor switches of the output circuit. This makes it possible to determine a relatively accurate leakage inductance parameter in a relatively simple manner.

[0013] Preferably, the operating parameters present in the leakage inductance estimator include a period parameter that specifies a period of a periodic control signal provided by the control device to the semiconductor switches of the input circuit and / or to the semiconductor switches of the output circuit. The period parameter of the leakage inductance estimator is preferably provided by the control device. However, it is also conceivable for the leakage inductance estimator to be configured to determine the period parameter by measurement. This makes it possible to determine a relatively accurate leakage inductance parameter in a relatively simple manner.

[0014] In a preferred embodiment, the input circuit and / or the output circuit comprises at least one inductance electrically connected to a bridge point of the bridge circuit of the input circuit or the output circuit located between two of the semiconductor switches, and the operating parameters comprise at least one current parameter indicating an electrical current flowing through the inductance. The current parameter can be provided to the leakage inductance estimator by the input circuit or the output circuit, for example, by a monitoring device of the input circuit or the output circuit, or the leakage inductance estimator can be configured to determine the current parameter by measurement.Particularly preferably, the input circuit or the output circuit comprises a number of inductors corresponding to the number of half-bridges in the bridge circuit, each of which is electrically connected to the bridge point of one of the half-bridges. The operating parameters for each inductor include an individual current parameter that specifies the electrical current flowing through the respective inductor. This makes it possible to determine a relatively accurate leakage inductance parameter in a relatively simple manner.

[0015] Preferably, the control device is provided with the leakage inductance parameter, and the control device is configured to adjust a period of a periodic control signal provided to the semiconductor switches of the input circuit and / or to the semiconductor switches of the output circuit based on the leakage inductance parameter. If the input circuit and the output circuit each have their own control device, the leakage inductance parameter is preferably provided to both control devices, and both control devices are configured to adjust the period of the control signals provided by the respective control device based on the leakage inductance parameter. This makes it possible to easily compensate for the effects of the transformer's leakage inductance.

[0016] In a preferred embodiment, the operating parameters comprise at least one input circuit voltage parameter that specifies an electrical voltage of the input circuit, and at least one output circuit voltage parameter that specifies an electrical voltage of the output circuit. The input circuit voltage parameter and the output circuit voltage parameter can be provided to the leakage inductance estimator by the input circuit and the output circuit, for example, by monitoring devices of the input circuit and the output circuit, or the leakage inductance estimator can be configured to determine the input circuit voltage parameter and the output circuit voltage parameter by measurement. This makes it possible to determine a relatively accurate leakage inductance parameter in a relatively simple manner.An embodiment of the present invention is described below with reference to the attached figure, which shows a schematic diagram of a DC-DC converter according to the invention.

[0017] The figure shows a DC-DC converter 100 according to the invention, which comprises a transformer 1, an input circuit 2, an output circuit 3, and a leakage inductance estimator 4.

[0018] The transformer 1 comprises an input winding 1 .1 with a number of turns N1 , an output winding 1 .2 with a number of turns N2 , and a transformer inductance 1 .3, which in the schematic diagram shown is intended to illustrate a leakage inductance of the transformer 1.

[0019] The input circuit 2 is configured to receive an input DC voltage lie at input terminals 2.1 a, 2.1 b.

[0020] The input circuit 2 comprises four semiconductor switches 2.2a - 2.2d, which are connected in the form of a bridge circuit 2.3, wherein a first semiconductor switch 2.2a and a second semiconductor switch 2.2b are arranged in a first half-bridge 2.3.1a of the bridge circuit 2.3, and wherein a third semiconductor switch 2.2c and a fourth semiconductor switch 2.2d are arranged in a second half-bridge 2.3.1b of the bridge circuit 2.3.

[0021] The two half-bridges 2.3.1 a, 2.3.1 b of the bridge circuit 2.3 are each electrically connected to a terminal circuit 2.6, which comprises one or more capacitors (not shown here for reasons of clarity).

[0022] The bridge circuit 2.3 is electrically connected to the transformer inductance 1.3 and the input winding 1.1 of the transformer 1 via a first bridge point 2.3.2a located on the first half-bridge 2.3.1a between the first semiconductor switch 2.2a and the second semiconductor switch 2.2b and a second bridge point 2.3.2b located on the second half-bridge 2.3.1b between the third semiconductor switch 2.2c and the fourth semiconductor switch 2.2d.

[0023] The input circuit 2 further comprises a control device 2.4 which is electrically connected to the control inputs of all four semiconductor switches 2.2a - 2.2d (not shown here for reasons of clarity) and which is configured to provide periodic control signals with a duty cycle De and a period duration T to the control inputs of the four semiconductor switches 2.2a - 2.2d in order to control the four semiconductor switches 2.2a - 2.2d.

[0024] The control device 2.4 is configured to control the four semiconductor switches 2.2a - 2.2d in a known manner such that an input alternating voltage Uew is present between the bridge points 2.3.2a, 2.3.2b of the bridge circuit 2.3 during operation and is thus provided to the transformer 1.

[0025] The input circuit 2 further comprises a first input circuit inductance 2.5a and a second input circuit inductance 2.5b, wherein the first input circuit inductance 2.5a is electrically connected on one side to the first bridge point 2.3.2a and on the other side to the first input terminal 2.1a, and wherein the second input circuit inductance 2.5b is electrically connected on one side to the second bridge point 2.3.2b and on the other side to the first input terminal 2.1a.

[0026] The input circuit 2 further comprises a monitoring device 2.7 which is configured to metrologically determine a first input circuit current parameter P-Ie1 which indicates an electrical input circuit current Ie1 flowing through the first input circuit inductance 2.5a, a second input circuit current parameter P-Ie2 which indicates an electrical input circuit current Ie2 flowing through the second input circuit inductance 2.5b, and an input circuit voltage parameter P-Ueg which indicates the input DC voltage lieg applied to the input terminals 2.1a, 2.b. The output circuit 3 comprises four semiconductor switches 3.1 a - 3.1 d, which are connected in the form of a bridge circuit 3.2, wherein a first semiconductor switch 3.1 a and a second semiconductor switch 3.1 b are arranged in a first half-bridge 3.2.1 a of the bridge circuit 3.2, and wherein a third semiconductor switch 3.1 c and a fourth semiconductor switch 3.1 d are arranged in a second half-bridge 3.2.1 b of the bridge circuit 3.2.

[0027] The two half-bridges 3.2.1 a, 3.2.1 b of the bridge circuit 3.2 are each electrically connected to output terminals 3.3a, 3.3b of the output circuit 3.

[0028] The bridge circuit 3.2 is electrically connected to the output winding 1 .2 of the transformer 1 via a first bridge point 3.2.2a located on the first half-bridge 3.2.1a between the first semiconductor switch 3.1a and the second semiconductor switch 3.1b and a second bridge point 3.2.2b located on the second half-bridge 3.2.1b between the third semiconductor switch 3.1c and the fourth semiconductor switch 3.1d, so that an output alternating voltage Uaw is present between the bridge points 3.2.2a, 3.2.2b of the output circuit 3 during operation, the amplitude of which voltage depends on the ratio N1 / N2 between the number of turns N1 of the input winding 1 .1 of the transformer 1 and the number of turns N2 of the output winding 1 .2 of the transformer 1.

[0029] During operation, the output circuit 3 therefore receives the output alternating voltage Uaw from the transformer 1 via the bridge points 3.2.2a, 3.2.2b.

[0030] The output circuit 3 further comprises a control device 3.4, which is electrically connected to the control inputs of all four semiconductor switches 3.1a - 3.1d (not shown here for reasons of clarity), and which is configured to provide periodic control signals with a duty cycle Da and period duration T to the control inputs of the four semiconductor switches 3.1a - 3.1d for controlling the four semiconductor switches 3.1a - 3.1d. The control device 3.4 is configured to control the four semiconductor switches 3.1a - 3.1d in a known manner such that, during operation, a DC output voltage Uag is present between the output terminals 3.3a, 3.3b of the output circuit 3 and is thus provided by the output circuit 3 via the output terminals 3.3a, 3.3b.

[0031] The output circuit 3 further comprises a monitoring device 3.5 which is configured to determine by measurement an output circuit voltage parameter P-Uag which indicates the DC output voltage Uag present between the output terminals 3.3a, 3.3b.

[0032] The leakage inductance estimation device 4 is connected to the control device 2.4 and the monitoring device 2.7 of the input circuit 2 as well as to the control device 3.4 and the monitoring device 3.5 of the output circuit 3.

[0033] The leakage inductance estimation device 4 is configured to receive, as operating parameters of the input circuit 2, from the control device 2.4 of the input circuit 2 a duty cycle parameter P-De indicating the duty cycle De and a period duration parameter PT indicating the period duration T, and to receive the first input circuit current parameter P-Ie1, the second input circuit current parameter P-Ie2 and the input circuit voltage parameter P-Ueg from the monitoring device 2.7 of the input circuit 2.

[0034] The leakage inductance estimation device 4 is further configured to receive, as operating parameters of the output circuit 3, a duty cycle parameter P-Da indicating the duty cycle Da from the control device 3.4 of the output circuit 3 and to receive the output circuit voltage parameter P-Uag from the monitoring device 3.5 of the output circuit 3.

[0035] The leakage inductance estimation device 4 comprises a computing unit 4.1, which is provided with the aforementioned operating parameters of the input circuit 2 and the output circuit 3 and which is configured to calculate, by means of an algorithm based on the operating parameters, a leakage inductance parameter PL, which estimates an inductance value of the transformer inductance 1.3 and thus the leakage inductance of the transformer 1.

[0036] The computing unit 4 is specifically designed to calculate the leakage inductance parameter P- L according to the following mathematical formula:

[0037] ( KP- -U -ago), 2 • P - -T - ZP-Da

[0038] PL = - - - (1 - P-De) • — - - (1 - P-De)

[0039] The leakage inductance estimation device 4 is further configured to provide the determined leakage inductance parameter PL to the control device 2.4 of the input circuit 2 and to the control device 3.4 of the output circuit 3, wherein the control device 2.4 of the input circuit 2 and the control device 3.4 of the output circuit 3 are configured to adjust the period T of the control signals provided to the four semiconductor switches 2.2a - 2.2d of the input circuit 2 and to the four semiconductor switches 3.1a - 3.1d of the output circuit 3, respectively, based on the received leakage inductance parameter PL in order to compensate for the effects of the leakage inductance of the transformer 1 as well as possible.

[0040] List of reference symbols

[0041] 100 DC-DC converters

[0042] 1 transformer

[0043] 1.1 Input winding

[0044] 1.2 Output winding

[0045] 1.3 Transformer inductance

[0046] 2 input circuit

[0047] 2.1 a, 2.1 b input terminals

[0048] 2.2a - 2.2d Semiconductor switches

[0049] 2.3 Bridge circuit

[0050] 2.3.1 a, 2.3.1 b Half bridges

[0051] 2.3.2a, 2.3.2b Bridge points

[0052] 2.4 Control device

[0053] 2.5a, 2.5b Input circuit inductances

[0054] 2.6 Terminal circuit

[0055] 2.7 Monitoring device

[0056] 3 Output circuit

[0057] 3.1 a - 3.1 d Semiconductor switches

[0058] 3.2 Bridge circuit

[0059] 3.2.1 a, 3.2.1 b Half bridges

[0060] 3.2.2a, 3.2.2b Bridge points

[0061] 3.3a, 3.3b Output terminals

[0062] 3.4 Control device

[0063] 3.5 Monitoring device

[0064] 4 Leakage inductance estimator

[0065] 4.1 Calculation unit Ie1 , Ie2 input circuit currents

[0066] Uag output DC voltage

[0067] Uaw AC output voltage lieg DC input voltage

[0068] Uew input AC voltage

Claims

Patent claims 1 . DC-DC converter (100) comprising: a transformer (1), an input circuit (2) configured to receive an input DC voltage (Ueg) and to provide an input AC voltage (Uew) to the transformer (1), and an output circuit (3) configured to receive an output AC voltage (Uaw) from the transformer (1) and to provide an output DC voltage (Uag), characterized in that a leakage inductance estimation device (4) is provided, which is configured to determine and / or receive operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag) of the input circuit (2) and the output circuit (3) and, based on the operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag), to determine a leakage inductance parameter (PL) that represents a leakage inductance of the transformer (1). estimates.

2. DC-DC converter (100) according to claim 1, wherein the leakage inductance estimation device (4) comprises a computing unit (4.1) to which the operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag) are provided, and which is configured to calculate the leakage inductance parameter (PL) based on the operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag).

3. DC-DC converter (100) according to one of the preceding claims, wherein the input circuit (2) and / or the output circuit (3) comprises a plurality of semiconductor switches (2.2a - 2.2d, 3.1a - 3.1d) which are connected in the form of a bridge circuit (2.3, 3.2), and wherein a Control device (2.4, 3.4) is provided which is arranged to send periodic control signals to the semiconductor switches (2.2a - 2.2d) of the input circuit (2) and / or to the semiconductor switches (3.1 a - 3.1 d) of the output circuit (3) to provide.

4. DC-DC converter (100) according to claim 3, wherein the operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag) comprise a duty cycle parameter (P-De, P-Da) which indicates a duty cycle (De, Da) of a periodic control signal provided by the control device (2.4, 3.4) to the semiconductor switches (2.2a - 2.2d) of the input circuit (2) or to the semiconductor switches (3.1a - 3.1d) of the output circuit (3).

5. DC-DC converter (100) according to claim 3 or 4, wherein the operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag) comprise a period parameter (PT) which indicates a period (T) of a periodic control signal provided by the control device (2.4, 3.4) to the semiconductor switches (2.2a - 2.2d) of the input circuit (2) and / or to the semiconductor switches (3.1a - 3.1d) of the output circuit (3).

6. DC-DC converter (100) according to one of claims 3 to 5, wherein the input circuit (2) and / or the output circuit (3) comprises an inductance (2.5a, 2.5b) which is electrically connected to a bridge point (2.3.2a, 2.3.2b) located between two of the semiconductor switches (2.2a - 2.2d), and wherein the operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag) comprise a current parameter (P-Ie1, P-Ie2) which indicates an electrical current (Ie1, Ie2) flowing through the inductance (2.5a, 2.5b).

7. DC-DC converter (100) according to one of claims 3 to 6, wherein the control device (2.4, 3.4) is provided with the leakage inductance parameter (PL), and wherein the control device (2.4, 3.4) is configured to determine a period duration (T) of a signal applied to the semiconductor switches (2.2a - 2.2d) of the Input circuit (2) and / or to the semiconductor switches (3.1 a - 3.1 d) of the output circuit (3) provided periodic control signal based on the leakage inductance parameter (PL).

8. DC-DC converter (100) according to one of the preceding claims, wherein the operating parameters (P-De, PT, P-Ie1, P-Ie2, P-Ueg, P-Da, P-Uag) comprise an input circuit voltage parameter (P-Ueg) indicating an electrical voltage (Ueg) of the input circuit (2), and an output circuit voltage parameter (P-Uag) indicating an electrical voltage (Uag) of the output circuit (3).

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