Dual active bridge converter cell with split energy transfer inductor

Abstract

The dual active bridge DC / DC converter according to the present application comprises: a first DC link, preferably comprising a first DC link capacitor; a converter bridge connected to the first DC link; a transformer, preferably a medium frequency transformer, having a primary side and a secondary side; the primary side of the transformer comprises a plurality, i.e. M>1, of primary windings, each of the plurality of primary windings having a first terminal and a second terminal; wherein the dual active bridge DC / DC converter further comprises a first plurality, i.e. M, of energy transfer inductors; and wherein for each of the M primary windings a different energy transfer inductor of the first plurality of energy transfer inductors is connected between said primary winding bridge and the converter bridge.

Description

Technical Field

[0001] This invention relates to the field of power electronics. It specifically relates to a dual active bridge DC / DC converter according to the independent patent claims. Background Technology

[0002] Transformers handling large currents (hundreds of amperes and above, especially above 200A) at high frequencies (especially above 3 kHz) are difficult to manufacture with low-cost and / or off-the-shelf components due to several effects that are negligible at lower frequencies (especially below 1 kHz) and / or for low currents (especially below 100 A). Typical applications involving such high frequencies and / or currents are medium-frequency transformers frequently used in solid-state transformers, particularly for SSTs configured as AC / DC converters for applications such as electric vehicle (EV) fast charging, photovoltaic (PV) solar energy, battery energy storage systems (BESS), onshore and offshore wind power, and connecting distributed power sources to medium-voltage (MV) grids in data centers. However, this typical application can also be in transformers without MV insulation requirements, commonly used in high-power low-voltage DC / DC converters with charging terminals of EV fast chargers that require electrical insulation. A particular example of such a DC / DC converter is a dual active bridge converter, as exemplarily described in Swiss Patent Application Publication CH 707533 A2 or U.S. Patent Application Publication CH 2018 / 0159435 A1 (both applications are incorporated herein by reference in their entirety).

[0003] To minimize high-frequency losses in transformer coils, one approach is to use Ritz wire to form the coil windings. While Ritz wire is several times more expensive than solid copper wire, it can be purchased "off the counter" for AC currents up to 100-200 A (RMS). Ritz wire consists of a large number of transposed steel strands, typically made of copper, and can have a total cross-sectional area up to 0.5 cm². 2 In cases where readily available, this allows for a maximum current of 100-200 A. rms Within the range (assuming a fill factor between 0.4 and 0.9, especially at least about 0.8, and a current density of 2.5…5 A / mm²), 2The larger currents typically found in the applications listed above require larger cross-sections, and bending becomes increasingly difficult. Ritz wires are typically not made of aluminum because it is extremely difficult to reliably contact all the strands on the wire terminals using aluminum (e.g., the 900 strands with a diameter of 0.2 mm in the copper Ritz wire mentioned above). Copper Ritz wire is at least 2-4 times more expensive than pure copper, and copper is about 3 times more expensive than aluminum. For the larger currents (>100 A) typically found in the applications listed above, several copper Ritz wires must be connected in parallel, which often results in circulating currents due to stray magnetic flux between the parallel wires, significantly increasing losses.

[0004] To optimize and / or minimize manufacturing workload and required resources, aluminum foil windings and / or pure copper, commonly used in 50Hz transformers, will be the preferred choice for the coils. At high frequencies, winding losses in foil increase significantly due to the skin effect and proximity effect. If a single foil is used, the frequency defines the required foil thickness, and the desired or required current defines the foil height, which in turn determines the transformer height. Therefore, for high current and high frequencies, the transformer shape will deviate significantly from a cubic shape, resulting in higher weight, core losses, and increased resource and workload requirements (requiring a larger core volume).

[0005] If parallel foils are used, the height of a single foil may be reduced, but strong circulating currents may be generated due to the stray magnetic field between the parallel foils, which will significantly increase losses (similar to the effect of parallel wires).

[0006] A major problem with both copper Ritz wire and copper foil designs is the circulating current between parallel conductors, which typically increases winding losses significantly, thereby reducing transformer rated power and / or significantly increasing transformer costs (USD / kW). In promising distributed energy applications such as EV fast charging, PV solar, battery storage systems, wind power, or data centers, the medium-frequency transformer (MFT) is a critical component. For higher currents (especially above 100A), simply scaling up 50 / 60 Hz technology and / or using off-the-shelf Ritz wire or low-cost foil wire results in significant losses due to high-frequency induced circulating currents, which substantially degrade transformer performance.

[0007] The generation of circulating current, especially in the configuration of two or more wires, foils, or other conductors forming parallel windings (where each winding comprises multiple turns), can be understood as follows: each turn is exposed to a stray magnetic field, for example, in a winding window formed by the core of a transformer. Parallel Ritz wires forming separate windings connected at the input and output of the transformer form a loop, which is exposed to the stray magnetic field. The stray magnetic field varies with the operating frequency of the MFT, generating a voltage that drives the circulating current in this loop. The circulating current increases the nominal current in the MFT, which may result in a single Ritz wire carrying more than half of the nominal current, while the parallel wires correspondingly carry less than half of the nominal current. If the circulating current is large enough, a single Ritz wire can carry more than the total nominal current, while the parallel wires carry a negative (180° phase shift) current. In this way, not only is the total available copper cross-section effectively reduced by 50%, but additional losses are also introduced, and the maximum output power of the MFT is reduced by two or more times.

[0008] Recent solutions for limiting circulating current require additional components, increased manufacturing effort, and additional space, and may lead to additional problems. One recent solution involves transposing parallel-connected wires or foils (e.g., provided by intertwined or otherwise twisted or interlaced parallel wires). This requires additional manufacturing effort (especially for foil windings), resulting in increased effective wire length, limited efficiency in MFTs with only a few winding turns, and may lead to high-voltage insulation challenges (e.g., due to geometric inhomogeneities near the transposition location). Alternatively, a common-mode filter can be added between the parallel wires or foils. However, this requires additional components, thus potentially leading to higher costs and manufacturing effort, and requiring additional space and / or other resources.

[0009] The object of this invention may be to effectively suppress circulating current in a dual active bridge DC-DC converter. Another object of this invention may be to provide a method to completely block circulating current by changing the topology of a dual active bridge DC / DC converter without any additional components or resources. Summary of the Invention

[0010] According to the independent patent claims, these objectives are achieved by a dual active bridge DC / DC converter with a combination of features. Other exemplary embodiments will become apparent from the dependent claims and the following description, taken in conjunction with the accompanying drawings.

[0011] The dual active bridge DC / DC converter according to the present invention includes: a first DC link, preferably including a first DC link capacitor; a converter bridge connected to the first DC link; a transformer, preferably an intermediate frequency transformer, having a primary side and a secondary side; the primary side of the transformer includes a plurality of (M>1) primary windings, each of the plurality of primary windings having first and second terminals; wherein the dual active bridge DC / DC converter further includes a first plurality of (M) energy transfer inductors; and wherein, for each primary of the M primary windings, different energy transfer inductors of the first plurality of energy transfer inductors are connected between the primary winding bridge and the converter bridge.

[0012] A converter bridge can be considered as part of a DC / AC converter or inverter having an input terminal connected to a first DC link, which in turn can be connected to the grid or a DC power source (e.g., a PV solar system or BESS) via the converter, wherein the DC / AC converter is configured to provide AC voltage and / or current at the output terminal of the DC / AC converter.

[0013] A transformer can be considered as part of an AC intermediate circuit having an input terminal and / or a primary side connected to the output terminal of the DC / AC converter. The AC intermediate circuit may include additional components, particularly inductors, connected in parallel with or in series with the input or output terminal or secondary side of the AC intermediate circuit and the transformer. The transformer may, in particular, be equipped with only a single primary winding and / or a single secondary winding, but will typically include multiple primary windings and / or multiple secondary windings.

[0014] The output and / or secondary side of the AC intermediate circuit can be connected to the input of an AC / DC converter configured to convert the AC current and / or voltage output from the AC intermediate circuit into a DC voltage and / or (intermittent) DC current at the output of the AC / DC converter. The output of the AC / DC converter can then be connected to a second DC link via a second converter bridge. This second DC link preferably includes a second DC link capacitor, at which a load can be connected. If the converter is suitable for bidirectional operation, particularly allowing bidirectional power flow, the load can at least temporarily act as a power source.

[0015] The first DC link can provide at least two voltage levels, specifically a zero or neutral level and a positive level. Specifically, the first DC link can also provide a positive level, a zero level, or a neutral level, and a negative voltage level.

[0016] A dual active bridge DC / DC converter may include more than one converter bridge (especially N>1 converter bridges in total) connected in parallel with a first DC link, and may also include a second plurality (i.e., N) of energy transfer inductors and a common node, wherein each of the second plurality (i.e. N) of energy transfer inductors is connected between one of the converter bridges and the common node; and each of the first plurality (i.e. M) of energy transfer inductors is connected between the common node and a first terminal of a different primary winding in a plurality of primary windings.

[0017] One or more converter bridges may be active bridges with arbitrary topologies that can apply at least one of two voltage levels provided by a first DC link to the input (especially the input terminal) of the AC intermediate circuit. This can include half-bridges, full-bridges, star-point clamped bridges, and any type of multi-stage topology. For example, a three-point bridge allows positive, negative, and zero voltages to be applied to the input of the AC intermediate circuit.

[0018] Therefore, one or more converter bridges may include multiple switches and corresponding switch connections, which allow for the establishment and termination of connections at the input of the AC intermediate circuit and at each voltage level. The switches may operate under the control of a control unit, control system, or controller, which may be internal to the DC / AC converter or located externally. The control may, in particular, be closed-loop control.

[0019] Preferably, if multiple converter bridges are connected in parallel to the first DC link, all such converter bridges have the same topology. Preferably, the corresponding switches of all converter bridges are configured to operate in a manner that is at least substantially synchronous. Specifically, the controller or control system can turn all corresponding switches on at least substantially synchronously and can turn all corresponding switches off at least substantially synchronously.

[0020] The switch can be a semiconductor switch, including transistors, especially BJT (bipolar junction transistor), MOSFET (metal-oxide-semiconductor field-effect transistor), IGBT (integrated gate bipolar transistor); or thyristors, especially GTO (gate turn-off thyristor), GCT (gate commutation thyristor), or IGCT (integrated gate commutation thyristor).

[0021] The foregoing aspects, as well as other aspects of the invention, will become apparent from the embodiments described in conjunction with the following drawings, and will be explained with reference thereto. Attached Figure Description

[0022] The subject matter of the invention will now be described in more detail with reference to exemplary embodiments shown in the accompanying drawings.

[0023] Figure 1A basic, prior art DC / DC dual active bridge (DAB) converter is shown.

[0024] Figure 2 A schematic diagram of a dual active bridge DC / DC converter according to an embodiment of the present invention is shown.

[0025] Figure 3 A schematic diagram of an exemplary dual active bridge DC / DC converter according to another embodiment of the present invention is shown.

[0026] Figure 4 A schematic diagram of an exemplary dual active bridge DC / DC converter according to yet another embodiment of the present invention is shown.

[0027] In principle, the same reference symbols in a diagram represent the same features or elements. Detailed Implementation

[0028] Figure 1 a) A basic, prior art dual active bridge DC / DC (DAB) converter 1 is shown, which can be considered a potential starting point for the present invention. The DC / AC converter 12 is configured to convert a DC voltage and / or current from a DC source (preferably including a DC link capacitor) connected to its input into an intermediate frequency (i.e., preferably in the frequency range between 500 Hz and 500 kHz) AC voltage and / or current. The AC voltage and / or current is fed into an AC intermediate circuit 14, which includes a transformer 141, particularly an intermediate frequency transformer (MFT), comprising a primary side and a secondary side, providing electrical insulation between the sides. Furthermore, the transformer may feature a coupling inductor L. m and L m' And stray inductance Ls, wherein one or more of its primary-side windings are connected via an inductance L DAB An inductor (sometimes called an energy transfer inductor) is connected to the DC / AC converter. The transformer converts the voltage and / or current on its primary side to the voltage and / or current on its secondary side in a known manner. The secondary-side voltage and / or current is then converted by the AC / DC converter 16 to a DC voltage and / or current at the output of the AC / DC converter 16. An optional inductor connected between the secondary side of the transformer and the AC / DC converter preferably has an inductance L'. DAB Its preferred form is at least substantially the same as L. DAB Equal, especially for a 1:1 transformer turns ratio. The DC / AC converter 12 may in particular include a plurality of semiconductor switches configured in a half-bridge configuration (corresponding to...). Figure 1 The configuration shown in b) is arranged or in a full-bridge configuration (corresponding to Figure 1The configuration shown in c) is arranged similarly. Similarly, the AC / DC converter 16 may in particular include a plurality of semiconductor switches configured in a half-bridge configuration (corresponding to...). Figure 1 The configuration shown in b) is arranged either in a full-bridge configuration (corresponding to...) Figure 1 The configuration shown in c) is arranged as follows.

[0029] Figure 2 A schematic diagram of a dual active bridge DC / DC converter according to an embodiment of the present invention is shown. The converter includes a first DC link 10, a DC / AC converter 112 including a pair of semiconductor switches S1 and S2, an AC intermediate circuit 114, an AC / DC converter 116, and a second DC link 18. Two parallel windings are provided on both the primary side 1001 and the secondary side 1002 of the transformer, and an energy transfer inductor L... DAB and L' DAB It is divided and distributed among parallel windings, wherein each winding has an inductance of L. DAB / 2 or L' DAB / 2 energy transfer inductors are used for the primary and secondary sides, respectively. For background information purposes only, a voltage source connected to the first DC link 10 and a resistive load (characterized by a resistance value R) connected to the second DC link 18 are also shown. load ), as well as the magnetic reluctance network 19 (grey) of the iron core, and the stray magnetic flux of the transformer.

[0030] Figure 3 A schematic diagram of a dual active bridge DC / DC converter according to another embodiment of the present invention is shown. The primary coil includes a plurality of (i.e., M=2) parallel windings (i.e., windings electrically connected in parallel), wherein each winding is formed by transformer wire, and wherein each wire or winding is connected to a second plurality of (i.e., M=2) inductors L. DAB2 A single inductor in the converter is connected to a common node C. The converter includes a first DC link 10, a DC / AC converter 212 (including multiple semiconductor switches S1, S2, S3, ..., S6), an AC intermediate circuit 214, an AC / DC converter 216, and a second DC link 18. The converter includes multiple active half-bridges connected to a single first DC link 10, and each of their outputs is connected via a first plurality of (i.e., N=3) inductors L. DAB1 A single inductor and a common node C are connected to the primary winding of an intermediate frequency transformer 2141, which also provides electrical insulation between the primary and secondary sides of the transformer. A common node C is provided as a single coupling point (wherein, inductor L...). DAB1 and inductor L DAB2 (All connected at this coupling point) allows for independent optimization of semiconductor switch and transformer wiring. The first multiple inductors L DAB1The inductances of all the inductors can be at least substantially the same, especially for a 1:1 transformer turns ratio. Similarly, the second or more inductors L DAB2 The inductances of all inductors can be at least substantially the same as each other, although not necessarily the same as the first plurality of inductors L. DAB1 The inductance is the same. For background information purposes only, a voltage source connected to the first DC link 10 and a resistive load (characterized by a resistor R) connected to the second DC link 18 are also shown. load ), and stray magnetic flux of the (gray) iron core magnetoresistive network 19 and transformer 2141.

[0031] Figure 4 A schematic diagram of an exemplary dual active bridge DC / DC converter according to another embodiment of the present invention is shown. The converter includes a first DC link 10, a DC / AC converter 312, an AC intermediate circuit 314, an AC / DC converter 316, and a second DC link 18. The DC / AC converter 312 of the dual active bridge DC / DC converter includes a plurality of (i.e., N) active half-bridges, where N is an integer multiple of the number M of the parallel primary windings of the transformer, and vice versa (e.g., N = M = 2). It can be seen that the energy transfer inductor L... DAB1 They are not connected to each other on their transformer sides, but are directly connected to the transformer windings respectively in the absence of a common node (as in the previous embodiment). Similarly, all energy transfer inductors L DAB1 The inductances can be at least substantially the same, especially for a 1:1 transformer turns ratio.

[0032] exist Figures 2 to 4 In the embodiment shown, the energy transfer inductor L DAB1 and (if present) L DAB2 replace Figure 1 a) Energy transfer inductor L DAB These inductors, together, act as energy transfer inductors in intermediate circuits 114, 214, and 314. Therefore, the energy transfer inductors can be considered as split-type energy transfer inductors, where each individual inductor acts as a partial energy transfer inductor.

[0033] Connecting the transformer windings in parallel using a split energy transfer inductor prevents circulating currents in the transformer windings, which would otherwise cause significant losses and / or significantly degrade converter performance in the MFT.

[0034] Furthermore, if a dual active bridge DC / DC converter comprises multiple (i.e., N>1) active half-bridges, the current through each active half-bridge or leg is no longer defined by power module parasitics, uneven temperature distribution, and / or semiconductor characteristics (not all chips are exactly the same) (due to the presence of partial energy transfer inductors), but by a split energy transfer inductor (within a specified range, the maximum deviation of this split energy transfer inductor from the reference inductor is limited, for example, 5%). This results in a uniform and stable current distribution without the need for additional measures or effort.

[0035] In all embodiments shown in the figure, the secondary side of the DC / DC converter (e.g.) Figures 2 to 4 (As shown on the right) can be implemented similarly to the primary side of the same or any other embodiment.

[0036] The advantageous features of the dual active bridge DC / DC converter according to the present invention are: • No additional components are required. The proposed split-type energy transfer inductor keeps the overall inductor size (especially the total / sum inductance) constant.

[0037] • An MFT with a single output or secondary-side terminal that connects all parallel windings internally can be used. For example, when the windings are made of foil (especially low-cost foil), the MFT is easier to manufacture while still meeting the stringent insulation requirements of high-voltage applications.

[0038] • As the maximum current that a single MFT can handle increases, the maximum and / or nominal power of each MFT may also increase. This is key to building cost-effective MFTs. In higher power (and therefore larger) MFTs, insulation effort (especially the volume required for sufficient insulation) is relatively reduced. Another way to provide higher power with higher current is to parallel the entire resonant converter or dual active bridge converter unit in the SST, or even the entire SST, to obtain the desired number of MFTs. However, this does not increase the power level of a single MFT.

[0039] • The circulating current in the windings of a parallel transformer, which consists of parallel conductors, is effectively suppressed by a split-type energy transfer inductor that blocks such currents—which also makes it possible to use the more common, smaller cross-section Litz wire, which is cheaper and can be manufactured with less effort and resources.

[0040] • Allows for low-cost implementation of dual active bridge DC / DC converter units by simply adding more half-bridges, enabling and / or activating existing high-performance semiconductor switches for high-current applications.

[0041] There is no theoretical limit to the number (N or N') of parallel converter bridges (i.e., power semiconductor switches).

[0042] • This allows for the low-cost implementation of resonant converter units and dual active bridges using wide-bandgap semiconductor switches designed for high-current applications, which would otherwise become increasingly difficult due to the high switching speed and small chip size (compared to non-wide-bandgap semiconductor switches).

[0043] • Simple and reliable, requiring no active current balancing control.

[0044] • A general concept of a dual active bridge DC / DC converter that must handle hundreds of amperes of current; applicable not only to units in MV grid-connected SSTs, but also to high-power low-voltage applications such as those required by various EV fast charger topologies.

[0045] Preferred embodiments of the invention (especially those described above) may be advantageously implemented in conjunction with one or more features detailed above, based on the items listed below, or in detail in the embodiments according to the further claims set forth below.

[0046] • A dual active bridge DC / DC converter, comprising: The first DC link 10 preferably includes a first DC link capacitor; The converter bridge connects to the first DC link; The transformer, preferably a medium-frequency transformer, has a primary side and a secondary side; The primary side of the transformer includes a plurality of (i.e., M>1) primary windings, each of the plurality of primary windings having first and second terminals; characterized in that: The first plurality of (i.e., M) energy transfer inductors; among which For each of the M primary windings, different inductors in the first plurality of energy transfer inductors are connected between the primary winding bridge and the converter bridge.

[0047] • A dual active bridge DC / DC converter, comprising: The first DC link preferably includes a first DC link capacitor; A DC / AC converter, connected to a first DC link, includes: The converter bridge connects to the first DC link; AC intermediate circuit, connected to the DC / AC converter and including: A transformer, preferably a medium-frequency transformer, has a primary side and a secondary side; The primary side includes multiple (i.e., M>1) primary windings; The first plurality of (i.e., M) energy transfer inductors; among which For each primary winding, a different inductor of the first plurality of energy transfer inductors is connected between said primary winding bridge and the converter bridge; an AC / DC converter, connected to the secondary side of the AC intermediate circuit, a second DC link, preferably comprising a second DC link capacitor, connected to the output end of the AC / DC converter.

[0048] • The dual active bridge DC / DC converter according to the preceding embodiment, wherein: said dual active bridge DC / DC converter comprises: a first plurality (i.e., N>1) of converter bridges (in particular, a total of N>1 converter bridges), connected in parallel to the first DC link; and the converter further comprises a second plurality (i.e., N) of energy transfer inductors, wherein each of the second plurality (i.e., N) of energy transfer inductors is connected between one of the converter bridges and a common node (C); each of the first plurality (i.e., M) of energy transfer inductors is connected between the common node and the first terminal of a different primary winding of the plurality of primary windings.

[0049] • The dual active bridge DC / DC converter according to any of the preceding embodiments, wherein each converter bridge is an inverter half-bridge comprising a first input terminal, a second input terminal, and an inverter bridge output end (said inverter bridge output end may optionally be conductively connected to the first or second input terminal via a plurality of semiconductor switches), wherein, for each inverter half-bridge, a different energy transfer inductor of the first plurality of energy transfer inductors is connected in series with the inverter bridge output end.

[0050] • The dual active bridge DC / DC converter according to any of the preceding embodiments, having: a plurality (i.e., O) of common nodes, in particular a total of O common nodes, wherein O<N and O<M; wherein each of the first plurality (i.e., N) of energy transfer inductors is connected between one of the converter bridges and one of the common nodes; each of the second plurality (i.e., M) of energy transfer inductors is connected between one of the common nodes and the first terminal of a different primary winding of the plurality of primary windings.

[0051] • The dual active bridge DC / DC converter according to any of the preceding embodiments, wherein M≠N, preferably M<N.

[0052] • A dual active bridge DC / DC converter according to the embodiments listed in the first and second items, wherein the converter includes a first plurality of (i.e., M>1) converter bridges, wherein the converter bridges and the primary winding are connected in pairs via different energy transfer inductors of the first plurality of energy transfer inductors, the different energy transfer inductors of the first plurality of energy transfer inductors being connected between each connection pair including one of the converter bridges and one of the primary windings.

[0053] • A dual active bridge DC / DC converter according to any of the foregoing embodiments, wherein: Each converter bridge is an inverter half-bridge, which includes a first input terminal, a second input terminal, and an inverter bridge output terminal (the inverter bridge output terminal may optionally be electrically connected to the first or second input terminal via multiple semiconductor switches). Each energy transfer inductor has a first terminal and a second terminal, and wherein For each inverter half-bridge, the first terminal of each corresponding energy transfer inductor among the multiple energy transfer inductors is connected to the corresponding inverter bridge output, and The second terminal of each of the first plurality of (i.e., M) energy transfer inductors is connected to a different primary winding.

[0054] • A dual active bridge DC / DC converter according to any of the foregoing embodiments, wherein, Each converter bridge is an inverter half-bridge, which includes a first input terminal, a second input terminal, and an inverter bridge output terminal (the inverter bridge output terminal may optionally be electrically connected to the first or second input terminal via multiple semiconductor switches). Each energy transfer inductor has a first terminal and a second terminal, and wherein For each inverter half-bridge, the first terminal of each of the multiple energy transfer inductors is connected to the corresponding inverter bridge output, and The second terminals of all the energy transfer inductors in the second plurality (i.e., N) energy transfer inductors are connected together at a common node.

[0055] • A dual active bridge DC / DC converter according to any of the foregoing embodiments, wherein the second terminals of all primary windings of a plurality of primary windings are connected together.

[0056] • A dual active bridge DC / DC converter according to any of the foregoing embodiments, wherein: The first DC link has a positive terminal and a negative terminal. The first input terminal of all inverter half-bridges is connected to the positive terminal, and The second input terminal of all inverter half-bridges is connected to the negative terminal.

[0057] • A dual active bridge DC / DC converter according to any of the above embodiments, wherein the first DC link further has a neutral terminal, and the second terminal of all the primary windings of the plurality of primary windings is connected to the neutral terminal.

[0058] • The dual active bridge DC / DC converter according to any of the foregoing embodiments further includes: The second DC link preferably includes a second DC link capacitor.

[0059] • The dual active bridge DC / DC converter according to any of the foregoing embodiments further includes: The second converter bridge is connected to the second DC link; The secondary side of the transformer includes a plurality of (i.e., M'>1) secondary windings, each of which has first and second terminals; A third, multiple (i.e., M') energy transfer inductors; and among them For each of the M' secondary windings, a different energy transfer inductor from the third plurality of energy transfer inductors is connected between the secondary winding bridge and the second converter bridge.

[0060] • The dual active bridge DC / DC converter according to any of the foregoing embodiments has: A fourth plurality of (i.e., N'>1) converter bridges, specifically a total of N'>1 converter bridges, are connected in parallel to the second DC link; wherein The converter also includes a fourth (i.e., N') energy transfer inductors, in which For each of the fourth plurality of converter bridges (i.e., N'>1), different inductors in the fourth plurality of energy transfer inductors are connected between the converter bridge and the plurality of secondary windings.

[0061] • The dual active bridge DC / DC converter according to any of the foregoing embodiments has: A fourth set of multiple (i.e., N'>1) converter bridges are connected in parallel to the second DC link; The converter also includes a fourth (i.e., N') energy transfer sensors, in which Each of the fourth (i.e., N') energy transfer sensors is connected between one of the converter bridges and another common node (C); Each of the third plurality of (i.e., M') energy transfer inductors is connected between the first terminals of the different secondary windings in the other common node and the plurality of secondary windings.

[0062] • A dual active bridge DC / DC converter according to any of the foregoing embodiments, wherein: Each of the first plurality of (i.e., N>1) converter bridges is an inverter bridge; The secondary side of the transformer includes at least one secondary winding; the converter also includes: The fourth set of multiple (i.e., N'>1) rectifier bridges are connected in parallel to the second DC link; The fourth multiple (i.e., N') energy transfer inductors, of which For each rectifier bridge, a different energy transfer inductor among the fourth plurality of energy transfer inductors is connected between the rectifier bridge and the plurality of secondary windings.

[0063] • A dual active bridge DC / DC converter according to any of the foregoing embodiments, wherein the converter bridge in the first plurality of (i.e., N>1) converter bridges is an active bridge, preferably configured to operate in at least substantially synchronous manner, and if present, the converter bridge in the second plurality of converter bridges is also an active bridge, preferably configured to operate in at least substantially synchronous manner.

[0064] Unless otherwise specified, a connection (especially a connection between any two entities, including nodes, points, terminals, components, devices, etc., or combinations thereof) means a conductive connection, particularly a trace or line on wires, cables, busbars, conductive rails, such as (printed) circuit boards, solder, etc. A conductive connection is preferably at least substantially direct, especially without any discrete components, particularly resistors, capacitors, inductors, or other passive or active components or devices connected between the connected entities. Therefore, a conductive connection has at least substantially negligible resistance, capacitance, and inductance, preferably at least substantially zero resistance, capacitance, and inductance. In particular, the resistance, capacitance, and inductance of a conductive connection are essentially parasitic. Furthermore, the resistance, capacitance, and inductance of a conductive connection are much smaller (preferably by a factor of 1 / 100, 1 / 1000, or 1 / 10000) than the resistance, capacitance, and impedance of resistors, capacitors, or inductors connected through and / or composed of circuits or networks containing conductive connections.

[0065] Unless otherwise specified, electrical connections or wiring connections are the same as those defined above.

[0066] Unless otherwise specified, if two entities (including nodes, points, terminals, elements, devices, etc., or combinations thereof) are referred to as a connection, electrical connection, or (electrically) connected together, then there is a connection as defined above between the two entities.

[0067] Unless otherwise specified, if a first entity and a second entity (including in particular a first and a second node, point, terminal, element, device, etc., or combinations thereof) are referred to as being connected via a third entity (including in particular a third node, point, terminal, element, device, or a third entity interposed therebetween), the connection as described above exists between the first entity and the third entity and between the third entity and the second entity. However, no connection as described above exists between the first entity and the second entity (at least there is substantially no substantially direct connection). Where explicitly specified, the third element may also be a connecting member, in particular a conductor, wire, cable, busbar, or the like. In this case, it can be considered that none of the above-mentioned connecting members exist except for the specified connecting member.

[0068] Unless otherwise stated, it is assumed in this patent application that the statement a≈b means |a-b| / (|a|+|b|)<10, preferably |a-b| / (|a|+|b|)<100, where a and b may represent any variable described and / or defined anywhere in this patent application or any variable otherwise known to a person skilled in the art. Furthermore, the statement that a is at least approximately equal to or at least approximately equivalent to b means that a≈b, preferably a=b. Furthermore, unless otherwise stated, it is assumed in this patent application that the statement a>>b means a>10b, preferably a>100b; and the statement a<<b means 10a<b, preferably 100a<b.

[0069] Unless otherwise stated, N, M, O, N', M', O' are used in this patent application to denote integers.

[0070] This description and the drawings which set forth aspects and embodiments of the present invention should not be considered as limiting the claims defining the protected invention. In other words, although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Various mechanical, compositional, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present specification and claims. In some instances, well-known circuits, structures, and techniques have not been shown in detail in order not to obscure the present invention. It is therefore to be understood that within the scope of the following claims, a person of ordinary skill in the art may make changes and modifications. In particular, the present invention covers further embodiments with any combination of features from different and / or separate embodiments as described above and below. Embodiments according to the invention may in particular include further and / or additional features, elements, aspects, etc. that are not shown in the drawings or described above.

[0071] This invention also separately covers all other features shown in the accompanying drawings, although they may not have been described in the foregoing or following description. Furthermore, the descriptions of various alternative embodiments and their features described in the figures, and the various alternatives themselves, can be omitted from the subject matter of this invention or the disclosed subject matter. This invention includes subject matter consisting of features defined in the claims or exemplary embodiments, as well as subject matter including said features.

[0072] Furthermore, in the claims, the word "comprising" does not exclude further or additional features, elements, steps, etc., and the indefinite articles "a" or "an" do not exclude plural. A single unit or step can perform the function of several features listed in the claims. The fact that certain measures are stated in mutually different dependent claims does not indicate that a combination of these measures cannot be used for advantageous purposes. Terms such as "substantially," "about," "probably," etc., relating to attributes, characteristics, or values ​​also specifically and accurately include the said attribute, characteristic, or value, respectively. In the context of a given numerical value or range, the terms "about" or "probably" refer to a numerical value or range, for example, within 20%, 10%, 5%, or 2% of a given numerical value or range, and particularly include the exact numerical value or range. Components described as coupled or connected may be electrically or mechanically directly coupled, or they may be indirectly coupled through one or more intermediate components. No reference marks in the claims shall be construed as limiting the scope.

Claims

1. A dual active bridge DC / DC converter, comprising: a) a first DC link (10); b) a first plurality of, i.e. N converter bridges, connected to the first DC link (10); c) a transformer (2141), the transformer having a primary side and a secondary side; d) the primary side of the transformer (2141) comprises a second plurality of, i.e. M>1 primary windings, each primary winding of the plurality of primary windings having a first terminal and a second terminal; characterized in that: e) The first multiple, i.e., N energy transfer inductors (L DAB1 The connection is made at the common node (C); where: f) The first plurality of energy transfer inductors (L DAB1 Different energy transfer inductors are connected between the common node (C) and the plurality of converter bridges; and g) Each first terminal of the M primary windings is connected to a second plurality of energy transfer inductors (L DAB2 The primary winding is connected to the common node (C), and the second terminals of all the primary windings in the plurality of primary windings are connected together.

2. The dual active bridge DC / DC converter according to claim 1, wherein: a) the plurality of, i.e. N>1 converter bridges are connected in parallel with the first DC link (10).

3. The dual active bridge DC / DC converter according to claim 1 or 2, wherein, Each of the converter bridges is an inverter half-bridge, which includes a first input terminal, a second input terminal, and an inverter bridge output terminal. For each inverter half-bridge, the first plurality of energy transfer inductors (L...) DAB1 Different energy transfer inductors in the inverter bridge are connected in series with the output terminal of the inverter bridge.

4. The dual active bridge DC / DC converter according to claim 3, wherein, The inverter bridge output end can be conductively connected to the first input terminal or the second input terminal via a plurality of semiconductor switches.

5. The dual active bridge DC / DC converter according to claim 2, further comprising: a) a plurality of, i.e. O common nodes, wherein O<N and O<M, and wherein b) each energy transfer inductor of the first plurality of, i.e. N energy transfer inductors is connected between one converter bridge of the converter bridges and one common node of the common nodes; c) each energy transfer inductor of the second plurality of, i.e. M energy transfer inductors is connected between one common node of the common nodes and the first terminal of a different primary winding of the plurality of primary windings.

6. The dual active bridge DC / DC converter according to claim 2, wherein, M≠N.

7. The dual active bridge DC / DC converter according to claim 6, wherein, M<N.

8. The dual active bridge DC / DC converter according to claim 1, wherein, The converter bridges and the primary windings are connected in pairs via different energy transfer inductors of the first plurality of energy transfer inductors, wherein a different energy transfer inductor of the first plurality of energy transfer inductors is connected between each connection pair comprising one converter bridge of the converter bridges and one primary winding of the primary windings.

9. The dual active bridge DC / DC converter according to claim 2, wherein: a) each converter bridge of the converter bridges is an inverter half-bridge, the inverter half-bridge comprising a first input terminal, a second input terminal, and an inverter bridge output end; b) each energy transfer inductor has a first terminal and a second terminal; and wherein c) for each inverter half-bridge, the first terminal of each respective energy transfer inductor among the first plurality of energy transfer inductors is connected to the corresponding inverter bridge output end; and d) the second terminals of all energy transfer inductors of the first plurality of, i.e. N energy transfer inductors are connected together at the common node (C).

10. The dual active bridge DC / DC converter according to claim 9, wherein, The inverter bridge output end can be conductively connected to the first input terminal or the second input terminal via a plurality of semiconductor switches.

11. The dual active bridge DC / DC converter according to claim 1 or 2, wherein: a) each converter bridge of the converter bridges is an inverter half-bridge, the inverter half-bridge comprising a first input terminal, a second input terminal, and an inverter bridge output end; b) each energy transfer inductor has a first terminal and a second terminal, and wherein: c) For each inverter half-bridge, the first terminal of each of the first plurality of energy transfer inductors is connected to the corresponding inverter bridge output. and d) The second terminal of each of the second plurality of energy transfer inductors, namely M energy transfer inductors, is connected to a different primary winding.

12. The dual active bridge DC / DC converter according to claim 11, wherein, The inverter bridge output can be electrically connected to the first input terminal or the second input terminal through multiple semiconductor switches.

13. The dual active bridge DC / DC converter according to claim 1 or 2, wherein: a) The first DC link has a positive terminal and a negative terminal; b) The first input terminals of all inverter half-bridges are connected to the positive terminal; and c) The second input terminal of all inverter half-bridges is connected to the negative terminal.

14. The dual active bridge DC / DC converter according to claim 1 or 2, wherein, The first DC link also has a neutral terminal, and the second terminal of all the primary windings of the plurality of primary windings is connected to the neutral terminal.

15. The dual active bridge DC / DC converter according to claim 1 or 2, further comprising: a) Second DC link.

16. The dual active bridge DC / DC converter according to claim 15, wherein, The second DC link includes a second DC link capacitor.

17. The dual active bridge DC / DC converter according to claim 15, further comprising: a) A second converter bridge, which is connected to the second DC link; b) The secondary side of the transformer, which includes a plurality of secondary windings, i.e., M'>1 secondary windings, each of the plurality of secondary windings having a first terminal and a second terminal; c) A third, or M', energy transfer inductors; and in d) For each of the M' secondary windings, different energy transfer inductors of the third plurality of energy transfer inductors are connected between the secondary winding bridge and the second converter bridge.

18. The dual active bridge DC / DC converter according to claim 17, comprising: a) A fourth, i.e., N'>1, converter bridge, which is connected in parallel with the second DC link; b) The converter also includes a fourth, or N', energy transfer inductors; in c) Each of the fourth plurality of, i.e., N' energy transfer inductors, is connected between one of the converter bridges and another common node (C') in the converter bridge; d) Each of the third plurality of energy transfer inductors, namely M', is connected between the other common node and the first terminal of a different primary winding in the plurality of primary windings.

19. The dual active bridge DC / DC converter according to claim 2, wherein, The converter bridges in the first plurality of converter bridges, i.e., N>1, are active bridges, and if they exist, the converter bridges in the second plurality of converter bridges are also active bridges.

20. The dual active bridge DC / DC converter according to claim 19, wherein, The active bridge is configured to operate in a manner that is at least substantially synchronous.

21. The dual active bridge DC / DC converter according to claim 1 or 2, wherein, The first DC link (10) includes a first DC link capacitor.

22. The dual active bridge DC / DC converter according to claim 1 or 2, wherein, The transformer is a medium-frequency transformer.

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