Power-electronics converter and power-electronics converter system

Abstract

The invention relates to a power electronics converter (1) having at least one high-voltage unit (5) which has at least one first high-voltage converter unit (11) and at least one second high-voltage converter unit (13), at least one low-voltage unit (9) which has at least one low-voltage converter unit (15), at least one transformer unit (7) which has at least one primary connection (23, 23') and at least one secondary connection (25, 25'), wherein the at least one primary connection (23, 23') is electrically connected to the at least one first high-voltage converter unit (11) and the at least one secondary connection (25, 25') is electrically connected to the at least one low-voltage converter unit (15), wherein at least two high-voltage units (5) are connected to form a double unit (31), wherein the two first high-voltage converter units (11) of the double unit (31) are connected together to form a three-stage high-voltage converter unit (33), wherein the two second high-voltage converter units (13) of the double unit (31) are connected in series at their inputs. The invention further relates to a power electronics converter system (57) having a plurality of power electronics converter cells (3), wherein at least one of the plurality of power electronics converter cells (3) has a power electronics converter (1) of the type described herein and comprising a double unit (31).

Description

[0001] Power electronic converter and power electronic converter system

[0002] The present invention relates to a power electronic converter and a power electronic converter system comprising a plurality of power electronic converter cells.

[0003] Power electronic converters are known from the state of the art and are used, among other things, in solid-state transformers (SSTs). Known power electronic converters are used in modern electrical distribution and transmission systems, as well as in the integration of renewable energy sources and their use in smart grids.

[0004] The known power electronic converters comprise a high-voltage unit, a transformer unit, and a low-voltage unit. The high-voltage unit converts the incoming high voltage into an intermediate stage suitable for the transformer unit. Power electronic components, including switching elements such as IGBT or MOSFET transistors, are used to handle the high voltages efficiently and safely. The transformer unit provides galvanic isolation and voltage matching between the high-voltage and low-voltage units. It transforms the voltage from the intermediate stage of the high-voltage unit to the required level of the low-voltage unit. The low-voltage unit then converts the transformed voltage into the required output voltage. The low-voltage unit also uses power electronic components to regulate and stabilize the output voltage.This ensures that the output power meets the requirements of the connected loads.

[0005] In the case of the power electronic converters mentioned above, high voltage refers to voltage levels significantly higher than the typical voltages in conventional low-voltage systems, for example, a voltage of approximately 20 kV, as used in solid-state transformers (SSTs). Such a voltage level is typical for applications in electrical power transmission and distribution, where high voltages are necessary for the efficient transmission of energy over long distances. The power electronic converters incorporate converter units within the high-voltage and low-voltage sections, which function as rectifiers or inverters, typically employing a full bridge design. A rectifier converts alternating current (AC) to direct current (DC), while an inverter performs the reverse process, converting DC to AC.A full bridge is a specific circuit topology that allows the direction of current flow through a load to be controlled, thus enabling efficient voltage conversion. Using such converter units makes it possible to convert high voltages and transform them according to the requirements of the downstream power grid or connected devices.

[0006] In known power electronic converters, it is also possible to incorporate a multitude of high-voltage units, transformer units, and low-voltage units, with the high-voltage units connected in series and the low-voltage units in parallel. As mentioned, the transformer units are positioned between the high-voltage and low-voltage units. Each high-voltage and low-voltage unit has its own control unit. This control unit enables precise and independent regulation of the individual units. However, this approach results in a complex design with a large number of components. Each control unit requires its own hardware and software, which increases the complexity and cost of the overall system.Furthermore, the large number of control units can impair the reliability and maintainability of the power electronic converters, as each additional unit represents a potential source of failure. The integration and synchronization of these numerous control units also requires complex communication technology to ensure coordinated and efficient operation.

[0007] In general, it is desirable to achieve a simple design for power electronic converters, particularly one that reduces the number of components, leading to a more stable, cost-efficient, and resource-saving design. Therefore, an object of the present invention is to provide a power electronic converter with the simplest possible design, particularly one that reduces the number of components, thus contributing to a more stable, cost-efficient, and resource-saving design.

[0008] According to a first aspect of the invention, the aforementioned problem is solved by a power electronic converter with the features of claim 1. The power electronic converter comprises at least one high-voltage unit, which includes at least one first high-voltage converter unit and at least one second high-voltage converter unit. Furthermore, the power electronic converter comprises at least one low-voltage unit, which includes at least one low-voltage converter unit. The power electronic converter comprises at least one transformer unit, which has at least one primary connection and at least one secondary connection. The at least one primary connection is electrically connected to the at least one first high-voltage converter unit, and the at least one secondary connection is electrically connected to the at least one low-voltage converter unit. At least two high-voltage units are connected to form a dual unit.The first two high-voltage converter units of the dual unit are connected together to form a three-stage high-voltage converter unit. The inputs of the second two high-voltage converter units of the dual unit are connected in series.

[0009] The power electronic converter comprises at least one high-voltage unit, which includes at least one first high-voltage converter unit and at least one second high-voltage converter unit. The first high-voltage converter unit serves to convert an alternating current (AC) entering the power electronic converter into a direct current (DC). Therefore, the first high-voltage converter unit can also be referred to as a rectifier. The second high-voltage converter unit serves to convert the DC voltage generated by the first high-voltage converter unit into a (high-frequency) alternating voltage, which is preferably adapted for the transformer unit. Therefore, the second high-voltage converter unit can also be referred to as an inverter.One advantage of the first and second high-voltage converter units is that the alternating current applied to the input of the power electronic converter, for example at a frequency of 50 Hz or 60 Hz, can be converted to a higher frequency, for example between 10 kHz and 100 kHz. This higher frequency allows for the use of lighter and smaller transformer units, resulting in a more compact design.

[0010] Furthermore, the power electronic converter has at least one low-voltage unit, which in turn includes at least one low-voltage converter unit. The low-voltage converter unit serves to convert the high-frequency alternating current transformed by the transformer unit into direct current, for example, at 700 V. Therefore, the low-voltage converter unit can also be referred to as a rectifier. This has the advantage of providing a stable low-voltage direct current supply.

[0011] The power electronic converter comprises at least one transformer unit, which has at least one primary connection and at least one secondary connection. The primary connection serves as the connection for the high-voltage unit, and the secondary connection serves as the connection for the low-voltage unit. As already mentioned, the transformer unit can be used to convert the high-frequency alternating current from the high-voltage unit. By converting high-frequency alternating current, a transformer unit with high efficiency and a small footprint can be realized.

[0012] Preferably, both the high-voltage unit and the low-voltage unit each have at least one electrical energy storage device, preferably a capacitor. The electrical energy storage device can smooth and / or filter the converted DC voltage, thus generating a DC voltage that is as uniform as possible. This increases the efficiency and performance quality of the power electronic converter.

[0013] Preferably, the first and second high-voltage converter units, as well as the low-voltage converter unit, feature a full bridge. A full bridge is defined in particular as a circuit topology in which two half-bridges are connected to form the full bridge. This allows for the provision of a particularly efficient and reliable power electronic converter.

[0014] The at least one primary connection is electrically connected to the at least one first high-voltage converter unit, and the at least one secondary connection is electrically connected to the at least one low-voltage converter unit. An electrical connection can be understood as direct electrical conductors that enable current flow between the various components. The electrical connection may have suitable insulation and protective devices to prevent short circuits and electrical disturbances. The electrical connection may include a high-voltage cable and terminals or connectors that establish the connection of the second high-voltage converter unit to the primary connection and the low-voltage converter unit to the secondary connection. This allows for a particularly safe and robust electrical connection between the high-voltage unit and the low-voltage unit and the transformer unit.

[0015] At least two high-voltage units are connected to form a dual unit. A dual unit is defined as an electrical unit that, in particular, comprises at least two galvanically connected high-voltage units, preferably connected in such a way that the dual unit can accept and convert the same voltages as two separate high-voltage units. The dual unit can have the same switching elements as two separate high-voltage units. One advantage of the dual unit is that, compared to two separate high-voltage units, only one control unit is required to control the switching elements of the dual unit. This advantageously allows for a reduction in the number of components of the power electronic converter.

[0016] The first two high-voltage converter units of the dual unit are connected together to form a three-stage high-voltage converter unit. A three-stage high-voltage converter unit is understood to be a converter unit that, in particular, enables at least three stages or voltage levels, for example, positive voltage, zero voltage, and negative voltage. Preferably, the three-stage high-voltage converter unit comprises a 3-level NPC (Neutral Point Clamped) full bridge, which includes a neutral point and clamping diodes that serve to generate the three voltage levels. By dividing the input voltage into three stages, a finer voltage division can be achieved. The three-stage high-voltage converter unit is advantageously configured to generate or convert the same voltage as two first high-voltage converter units connected in series.The three-stage high-voltage converter unit therefore enables simple control of the power electronic converter.

[0017] The two secondary high-voltage converter units of the dual unit are connected in series at their inputs. This series connection allows the voltage supplied by the three-stage high-voltage converter unit to be divided between the two secondary high-voltage converter units. The combination of the three-stage high-voltage converter unit and the two secondary high-voltage converter units connected in series enables the dual unit to advantageously output the same voltage as two high-voltage units connected in series. Therefore, the dual unit reduces the number of components required for the same voltage output, as only one control unit is needed for the entire dual unit.

[0018] In summary, it can be stated that the present invention provides a power electronic converter which has a simple structure and in which, in particular, the number of components can be reduced, which can contribute to a more stable, cost-efficient and resource-saving design.

[0019] In one embodiment, the transformer unit has a first primary terminal and a second primary terminal, with each of the two second high-voltage converter units of the dual unit being connected at its output to one of the two primary terminals. The first and second primary terminals allow a single transformer unit to be used for voltage transformation of the two outputs of the second high-voltage converter units. This further reduces the number of components in the power electronic converter, resulting in a simpler and more compact design. The dual unit can also include a transformer unit, which may be the aforementioned unit or another transformer unit. In other words, the transformer unit can be an integral part of the dual unit.

[0020] In one embodiment, the transformer unit (optionally the dual unit) has a magnetic core with a first primary winding wound around a first leg and a second primary winding wound around a second leg, wherein the first primary terminal is connected to the first primary winding and the second primary terminal is connected to the second primary winding. Because the first primary winding is wound around a first leg of the magnetic core and the second primary winding is wound around a second leg of the magnetic core, the transformer unit (of the dual unit) requires only a single magnetic core. The magnetic core can have various shapes suitable for accommodating the first primary winding and the second primary winding and for transforming the voltages from the two outputs of the two secondary high-voltage converter units.This arrangement of the first and second primary windings allows for a particularly compact design of the power electronic converter.

[0021] In one embodiment, at least two low-voltage units can be provided, which are connected to the transformer unit (optionally the dual unit), wherein the transformer unit has two secondary terminals, each of which is connected to one of the two low-voltage units (optionally the dual unit). The two secondary terminals of the transformer unit allow the dual unit to be connected to two low-voltage units to form the power electronic converter. This has the advantage that the dual unit can be backward compatible and / or retrofitted into an existing power electronic converter or used with previously known low-voltage units. It can be provided that the dual unit can comprise the at least two low-voltage units.In other words, the at least two low-voltage units can be a component of the double unit. In one embodiment, the transformer unit (of the double unit) has a magnetic core with a first secondary winding wound around a first leg and a second secondary winding wound around a second leg, the first secondary terminal being connected to the first secondary winding and the second secondary terminal being connected to the second secondary winding. The first secondary winding being wound around the first leg and the second secondary winding being wound around the second leg advantageously enable the transformer unit (of the double unit) to transform two voltages each, those of the first and second primary and secondary windings, so that a transformed voltage can be provided at both secondary terminals for the two low-voltage units.This allows for a particularly simple and space-saving design of the power electronic converter.

[0022] In one embodiment, the dual unit comprises a low-voltage unit and the transformer unit a secondary terminal, with one secondary terminal being connected to the low-voltage unit. The transformer unit may have a secondary winding connected to the secondary terminal. This secondary winding may consist of two windings connected in series, configured to transform the voltages of the first and second primary windings and provide a transformed voltage at the secondary terminal. As mentioned previously, the dual unit is advantageously configured to provide the same voltage and current as two high-voltage and low-voltage units. For this purpose, the low-voltage unit (of the dual unit) may include components, such as switching elements, configured to carry twice the current.This has the advantage that the double unit only has one low-voltage unit, which can contribute to a space-saving design.

[0023] In one embodiment, the dual unit comprises two transformer units, with each of the dual unit's two high-voltage inverters connected at its output to one of the two transformer units. The two outputs of the second high-voltage converter unit allow the dual unit to be connected to two transformer units to form the power electronic converter. This has the advantage that the dual unit can be backward compatible and / or retrofitted into an existing power electronic converter or used with previously known transformer units.

[0024] In one embodiment, the high-voltage units and / or the low-voltage units each have a control unit for controlling the high-voltage and / or low-voltage converter units. These control units preferably serve to regulate and monitor the converter units of the high-voltage and / or low-voltage units. In particular, the control unit controls the switching states of the switching elements to achieve the most efficient voltage conversion possible. For example, the control unit can generate PWM (pulse width modulation) signals to achieve or set a desired output voltage and frequency. The control unit advantageously enables particularly effective, reliable, and safe control of the converter units.

[0025] In one embodiment, the dual unit includes a (common) high-voltage control unit for controlling the two high-voltage units. The high-voltage control unit of the dual unit can be considered a common control unit for the two high-voltage units of the dual unit. This common high-voltage control unit advantageously reduces the number of control units in the power electronic converter, since not each high-voltage unit has its own control unit, but rather the two high-voltage units can be controlled by a single common high-voltage control unit. This has the advantage of reducing the number of components and the amount of material used in the power electronic converter.

[0026] In one embodiment, the dual unit includes a (common) low-voltage control unit for controlling the two low-voltage units. The low-voltage control unit of the dual unit can be considered a common control unit for the two low-voltage units of the dual unit. This common low-voltage control unit reduces the number of control units of the power electronic converter, since not each low-voltage unit of the dual unit has its own control unit, but rather the two low-voltage units can be controlled by a single common low-voltage control unit. This has the advantage of reducing the number of components and the amount of material used in the power electronic converter.

[0027] Preferably, the dual unit comprises a central control unit that includes both the high-voltage and low-voltage control units. This central control unit allows for a further advantageous reduction in the number of control units, resulting in lower material costs and a further reduction in the number of components.

[0028] In a second aspect of the invention, the aforementioned problem is solved by a power electronic converter system with the features of claim 11. The power electronic converter system comprises a plurality of power electronic converter cells. The plurality of power electronic converter cells comprises at least one high-voltage unit, which includes at least one first high-voltage converter unit and at least one second high-voltage converter unit. The plurality of power electronic converter cells comprises at least one low-voltage unit, which includes at least one low-voltage converter unit. Furthermore, the plurality of power electronic converter cells comprises at least one transformer unit, which has at least one primary connection and at least one secondary connection.At least one of the many power electronic converter cells features a power electronic converter with a dual unit as described here.

[0029] The power electronic converter system can, for example, be an SST of the type mentioned above. The dual unit design allows for a reduction in the number of components, particularly the number of control units, within the power electronic converter system. Compared to two separate power electronic converter cells, each comprising a high-voltage unit, a transformer unit, and a low-voltage unit, each with its own control unit, the dual unit requires only one control unit to manage both high-voltage units. Advantageously, the dual unit can supply and convert the same voltage. Therefore, the number of control units can be halved by using the dual unit compared to two separate power electronic converter cells.

[0030] Further features, advantages, and applications of the present invention will become apparent from the following description of the embodiments and the figures. All features described and / or illustrated, individually and in any combination, constitute the subject matter of the invention, irrespective of their composition in the individual claims or their cross-references. In the figures, the same reference numerals denote identical or similar objects.

[0031] Figure 1 shows a schematic representation of a power electronic converter as known from the prior art,

[0032] Figure 2 shows a schematic representation of a first embodiment of a power electronic converter described herein,

[0033] Figure 3 shows a schematic representation of the transformer unit of the double unit of the first embodiment from Figure 2,

[0034] Figure 4 shows a schematic representation of a second embodiment of a power electronic converter described herein,

[0035] Figure 5 shows a schematic representation of the transformer unit of the double unit of the second embodiment from Figure 4.

[0036] Figure 6 shows a schematic representation of a third embodiment of a power electronic converter described herein, and

[0037] Figure 7 shows a schematic representation of an embodiment of a power electronic converter system described herein. Figure 1 shows a schematic representation of a power electronic converter 1 as known from the prior art. The power electronic converter 1 has two power electronic converter cells 3, each comprising a high-voltage unit 5, a transformer unit 7, and a low-voltage unit 9. The high-voltage units 5 each comprise a first high-voltage converter unit 11 and a second high-voltage converter unit 13. The low-voltage unit 9 comprises a low-voltage converter unit 15.

[0038] The first and second high-voltage converter units 11, 13 and the low-voltage converter unit 15 feature a full bridge. This enables the provision of a particularly powerful and reliable power electronic converter 1.

[0039] The high-voltage unit 5 has two inputs 17 and serves to convert a high voltage input at the inputs 17 into an intermediate stage suitable for the transformer unit 7. For this purpose, the first and second high-voltage converter units 11, 13 have power electronic components, including switching elements 19 such as IGBT or MOSFET transistors. First, the alternating voltage applied to the inputs 17 is converted into a direct voltage by the first high-voltage converter unit 11.

[0040] The high-voltage unit 5 and the low-voltage unit 9 each have an electrical energy storage device 21 in the form of a capacitor. The electrical energy storage device 21 smooths and filters the converted DC voltage, thus generating a uniform DC voltage. This increases the efficiency and performance of the power electronic converter 1.

[0041] The first high-voltage converter unit 11 serves to convert an alternating current (AC) entering at the inputs 17 of the power electronic converter 1 into a direct current (DC). Therefore, the first high-voltage converter unit 11 can also be called a rectifier when the power flow is from AC to DC. When the power flow is from DC to AC, the first high-voltage converter unit 11 could be called an inverter. The second high-voltage converter unit 13 serves to convert the DC voltage generated by the first high-voltage converter unit 11 into a high-frequency AC voltage, which is preferably adapted for the transformer unit 7. Therefore, the second high-voltage converter unit 13 can also be called an inverter.The advantage of the first and second high-voltage converter units 11, 13 lies in the fact that the alternating current applied to the input 17 of the power electronic converter 1, for example with a frequency of 50 Hz or 60 Hz, can be converted to a higher frequency, for example with a frequency between 10 kHz and 100 kHz. The higher frequency allows for the use of lighter and smaller transformer units 7, resulting in a more compact design.

[0042] The transformer unit 7 has a primary connection 23 and a secondary connection 25. The primary connection 23 serves as the connection for the high-voltage unit 5 or the second high-voltage converter unit 13, and the secondary connection 25 serves as the connection for the low-voltage unit 9 or the low-voltage converter unit 15. The high-voltage unit 5 supplies a high-frequency current to the transformer unit 7, which is why it can be implemented with high efficiency and a small footprint.

[0043] The transformer unit 7 provides galvanic isolation and voltage matching between the high-voltage unit 5 and the low-voltage unit 9. It transforms the voltage from the intermediate stage of the high-voltage unit 5 to the required level of the low-voltage unit 9. The low-voltage unit 9 then converts the transformed voltage into the required output voltage, which is applied to outputs 27 of the power electronic converter cell 3. The low-voltage unit 9 also uses power electronic components, such as switching elements 19, to regulate and stabilize the output voltage. This ensures that the output power meets the requirements of the connected loads.

[0044] The low-voltage converter unit 15 serves to convert the high-frequency alternating current transformed by the transformer unit 7 into a direct current, for example at 700 V. This has the advantage that a stable low-voltage direct current supply can be provided at the outputs 27.

[0045] The high-voltage units 5 and the low-voltage units 9 each have a control unit 29 for controlling the high-voltage and low-voltage converter units 11, 13, 15. This control unit 29 serves to regulate and monitor the converter units of the high-voltage and / or low-voltage units 5, 9. In particular, the control unit 29 controls the switching states of the switching elements 19 to achieve efficient voltage conversion. For example, the control unit 29 can generate PWM (pulse-width modulation) signals to achieve a desired output voltage and frequency. The control unit 29 enables particularly effective, reliable, and safe control of the converter units.

[0046] Figure 2 shows a schematic representation of a first embodiment of a power electronic converter 1 described herein. In the first embodiment shown in Figure 2, two high-voltage units 5 are connected to form a dual unit 31. A dual unit 31 is understood to be an electrical unit comprising at least two galvanically connected high-voltage units 5, which are connected in such a way that the dual unit 31 can receive and convert the same voltages as two separate high-voltage units 5, as shown in Figure 1. The dual unit 31 can have the same switching elements 19 as two separate high-voltage units 5. The advantage of the dual unit 31 is that, compared to two separate high-voltage units 5, only one control unit 29 is required to control the switching elements 19 of the dual unit 31.This allows the number of components of the power electronic converter 1 to be reduced.

[0047] The first two high-voltage converter units 11 of the double unit 31 are connected together to form a three-stage high-voltage converter unit 33. A three-stage high-voltage converter unit 33 is defined as a converter unit that provides at least three stages or voltage levels, for example, positive voltage, zero, and negative voltage. The three-stage high-voltage converter unit 33 features a 3-level NPC (Neutral Point Clamped) full bridge, which includes a neutral point 35 and clamping diodes 37 that serve to generate the three voltage levels. By dividing the input voltage into three stages, a finer voltage division can be achieved. The three-stage high-voltage converter unit 33 is configured to generate or convert the same voltage as two first high-voltage converter units 11 connected in series.The three-stage high-voltage converter unit 33 thus enables simple control of the power electronic converter 1.

[0048] The two second high-voltage converter units 13 of the dual unit 31 are connected in series at their inputs. This series connection of the second high-voltage converter units 13 allows the voltage provided by the three-stage high-voltage converter unit 33 to be distributed between the two second high-voltage converter units 13. The three-stage high-voltage converter unit 33 and the two second high-voltage converter units 13 connected in series enable the dual unit 31 to output the same voltage as two high-voltage units 5 connected in series. Therefore, the dual unit 31 reduces the number of components required for the same voltage output, as only one control unit 29 is needed for the dual unit 31.

[0049] As just mentioned, the dual unit 31 includes the control unit 29, which can also be referred to as the high-voltage control unit for controlling the two high-voltage units. The high-voltage control unit of the dual unit 31 can be considered the common control unit 29 of the two high-voltage units 5 of the dual unit 31. The common high-voltage control unit reduces the number of control units 29 of the power electronic converter 1, since not each high-voltage unit 5 has its own control unit 29, but rather the two high-voltage units 5 can be controlled by a common high-voltage control unit. This has the advantage of reducing the number of components and the amount of material used in the power electronic converter 1.

[0050] In the first embodiment shown in Figure 2, the dual unit 31 comprises a single low-voltage unit 9 with a low-voltage converter unit 15. The transformer unit 7 of the dual unit 31 has a secondary connection 25, one of which is connected to the low-voltage unit 9. The dual unit 31 includes a transformer unit 7 having a first primary connection 23 and a second primary connection 23', with each of the two second high-voltage converter units 13 of the dual unit 31 being connected at its outputs to one of the two primary connections 23 and 23'. The first primary connection 23 and the second primary connection 23' allow a single transformer unit 7 to be used for voltage transformation of the two outputs of the second high-voltage converter units 13.This allows the number of components of the power electronic converter 1 to be further reduced, resulting in a simpler and more space-saving design. The transformer unit 7 of the double unit 31 of the first embodiment is described below with reference to Figure 3.

[0051] Figure 3 shows a schematic representation of the transformer unit 7 of the double unit 31 of the first embodiment shown in Figure 2. The transformer unit 7 of the double unit 31 has a magnetic core 39 with a first leg 41 and a second leg 43. A first primary winding 45 is wound around the first leg 41 and a second primary winding 47 is wound around the second leg 43, with the first primary terminal 23 being connected to the first primary winding 45 and the second primary terminal 23' being connected to the second primary winding 47. By winding the first primary winding 45 around the first leg 41 of the magnetic core 39 and the second primary winding 47 around the second leg 43 of the magnetic core 39, the transformer unit 7 of the double unit 31 requires only a single magnetic core 39.

[0052] The transformer unit 7 has a first secondary winding 49 wound around the first leg 41 and a second secondary winding 51 wound around the second leg 43. In the first embodiment, the first and second secondary windings 49, 51 are connected in series and connected to the secondary terminal 25. The two secondary windings 49, 51 connected in series are configured to transform the voltages of the first and second primary windings 45, 47 and to provide a transformed voltage at the secondary terminal 25. As already mentioned, the double unit 31 is configured to provide the same voltage and current as two high-voltage and low-voltage units 5, 9. For this purpose, the low-voltage unit 9 of the double unit 31 can have components, such as switching elements 19, which are configured to carry twice the current.This has the advantage that the double unit 31 only has one low-voltage unit 9, resulting in a space-saving design.

[0053] The first and second legs 41, 43 are connected via a first yoke 53 and a second yoke 55, so that the magnetic core 39 has a closed shape. The magnetic core 39 can have various shapes suitable for accommodating the first primary winding 45, the first secondary winding 49, the second primary winding 47, and the second secondary winding 51, and for transforming the voltages from the two outputs of the two second high-voltage converter units 13. This arrangement of the first and second primary windings 45, 47 allows for a particularly compact design of the power electronic converter 1.

[0054] Figure 4 shows a schematic representation of a second embodiment of a power electronic converter 1 described herein. The second embodiment differs from the first embodiment in that the power electronic converter 1 comprises a double unit 31 and two low-voltage units 9, which are connected to the transformer unit 7 of the double unit 31. The transformer unit 7 has two secondary terminals 25, 25', each of which is connected to one of the two low-voltage units 9. The two secondary terminals 25, 25' of the transformer unit 7 enable the double unit 31 to be connected to two low-voltage units 9 to form the power electronic converter 1.This has the advantage that the double unit 31 is backward compatible and can be retrofitted into existing power electronic converters 1 or used with already known low voltage units 9.

[0055] The dual unit 31 includes a control unit 29 for controlling the two high-voltage units 5. The two low-voltage units 9 each have their own control unit 29 for controlling the low-voltage converter units 15. In an alternative embodiment, the dual unit 31 includes the two low-voltage units 9, so that the dual unit 31 forms a self-contained unit with the two high-voltage units 5, the transformer unit 7, and the two low-voltage units 9. This has the advantage that, firstly, one control unit 29 can be used to control the dual unit 31, and secondly, that the dual unit 31 itself can be used as a power electronic converter 1 for voltage conversion. The transformer unit 7 of the dual unit 31 is described below with reference to Figure 5.

[0056] Figure 5 shows a schematic representation of a transformer unit 7 of the second embodiment shown in Figure 4. The transformer unit 7 of the double unit 31 has a magnetic core 39, a first primary winding 45 wound around a first leg 41, a first secondary winding 49 wound around the first leg 41, a second primary winding 47 wound around a second leg 43 and a second secondary winding 51 wound around a second leg 43, wherein the first secondary terminal 25 is connected to the first secondary winding 49 and the second secondary terminal 25' is connected to the second secondary winding 51.The first secondary winding 49, wound around the first leg 41, and the second secondary winding 51, wound around the second leg 43, enable the transformer unit 7 of the double unit 31 to transform two voltages each, from the first and second primary and secondary windings 45, 47, 49, 51, so that a transformed voltage can be provided at both secondary terminals 25, 25' for the two low-voltage units 9. This allows for a particularly simple and space-saving design of the power electronic converter 1.

[0057] Figure 6 shows a schematic representation of a third embodiment of a power electronic converter 1 described herein. The third embodiment differs from the second embodiment in that the dual unit 31 comprises two transformer units 7 and two low-voltage units 9, with the two secondary high-voltage inverters 13 of the dual unit 31 each being connected at their outputs to one of the two transformer units 7. The two outputs of the two secondary high-voltage converter units 13 allow the dual unit 31 to be connected to two transformer units 7 to form the power electronic converter 1. This has the advantage that the dual unit 31 is backward compatible and can be retrofitted into existing power electronic converters 1 or used with previously known transformer units 7 and low-voltage units 9.

[0058] A further difference between the third embodiment shown in Figure 6 and the second embodiment is that the dual unit 31 has a single control unit 29, which can also be referred to as a low-voltage control unit, for controlling the two low-voltage units 9. The low-voltage control unit of the dual unit 31 can be considered a common control unit 29 for the two low-voltage units 9 of the dual unit 31. This common low-voltage control unit reduces the number of control units 29 of the power electronic converter 1, since not each low-voltage unit 9 of the dual unit 31 has its own control unit 29, but rather the two low-voltage units 9 can be controlled by a single common low-voltage control unit. This has the advantage of reducing the number of components and the amount of material used in the power electronic converter 1.

[0059] In summary, it can be stated that the present invention provides a power electronic converter 1 which has a simple structure and in which, in particular, the number of components can be reduced, leading to a more stable, cost-efficient and resource-saving design.

[0060] Figure 7 shows a schematic representation of an embodiment of a power electronic converter system 57 described herein. The power electronic converter system 57 comprises a plurality of power electronic converter cells 3. The plurality of power electronic converter cells 3 comprises at least one high-voltage unit 5, which includes at least one first high-voltage converter unit 11 and at least one second high-voltage converter unit 13. The plurality of power electronic converter cells 3 comprises at least one low-voltage unit 9, which includes at least one low-voltage converter unit 15. Furthermore, the plurality of power electronic converter cells 3 comprises at least one transformer unit 7, which has at least one primary connection 23 and at least one secondary connection 25.At least one of the multiple power electronic converter cells 3 has a power electronic converter 1 described here with a double unit 31.

[0061] The power electronic converter system 57 can, for example, be an SST. The dual unit 31 allows for a reduction in the number of components, particularly the number of control units 29, in the power electronic converter system 57. Compared to two separate power electronic converter cells 3, each comprising a high-voltage unit 5, a transformer unit 7, and a low-voltage unit 9, each with its own control unit 29, the dual unit 31 has only one control unit 29 for controlling both high-voltage units 5, while the dual unit 31 can supply or convert the same voltage. Therefore, the number of control units 29 can be halved by the dual unit 31 compared to two power electronic converter cells 59.

[0062] The power electronic converter system 57 can comprise a plurality of power electronic converter cells 3 and a plurality of power electronic converters 1 with a dual unit 31. The power electronic converter system 57 can comprise one or more power electronic converters 1 according to one of the embodiments described herein. (List of reference symbols)

[0063] power electronic converter, power electronic converter cell, high-voltage unit, transformer unit, low-voltage unit

[0064] first high-voltage converter unit second high-voltage converter unit low-voltage converter unit input

[0065] Switching element

[0066] Energy storage

[0067] , 23' Primary connection

[0068] , 25' Secondary connection

[0069] Exit

[0070] control unit

[0071] Double unit

[0072] three-stage high-voltage converter unit neutral point

[0073] Terminal diode

[0074] magnetic core

[0075] first thigh

[0076] second thigh

[0077] first primary winding

[0078] second primary winding

[0079] first secondary winding

[0080] second secondary winding

[0081] first yoke

[0082] second yoke

[0083] power electronic converter system

Claims

Patent claims 1. Power electronic converter (1 ) with at least one high-voltage unit (5) comprising at least one first high-voltage converter unit (11) and at least one second high-voltage converter unit (13), at least one low-voltage unit (9) comprising at least one low-voltage converter unit (15), at least one transformer unit (7) having at least one primary terminal (23, 23') and at least one secondary terminal (25, 25'), wherein the at least one primary connection (23, 23') is electrically connected to the at least one first high-voltage converter unit (11) and the at least one secondary connection (25, 25') is electrically connected to the at least one low-voltage converter unit (15), wherein at least two high-voltage units (5) are connected to form a double unit (31), wherein the first two high-voltage converter units (11) of the double unit (31) are connected together to form a three-stage high-voltage converter unit (33), wherein the two second high-voltage converter units (13) of the double unit (31) are connected in series at their inputs.

2. Power electronic converter (1) according to claim 1, wherein the transformer unit (7) has a first primary connection (23) and a second primary connection (23'), wherein the two second high-voltage converter units (13) of the double unit (31) are each connected at their outputs to one of the two primary connections (23, 23').

3. Power electronic converter (1) according to claim 2, wherein the transformer unit (7) has a magnetic core (39) with a first primary winding (45) wound around a first leg (41) and a second primary winding (47) wound around a second leg (43), wherein the first 22 The primary terminal (23) is connected to the first primary winding (45) and the second primary terminal (23') is connected to the second primary winding (47).

4. Power electronic converter (1) according to one of claims 1 to 3, wherein at least two low-voltage units (9) are provided which are connected to the transformer unit (7), wherein the transformer unit (7) has two secondary connections (25, 25'), wherein one of the two secondary connections (25, 25') is connected to one of the two low-voltage units (9).

5. Power electronic converter (1) according to claim 4, wherein the transformer unit (7) has a magnetic core (39) with a first secondary winding (51) wound around a first leg (41) and a second secondary winding (53) wound around a second leg (43), wherein the first secondary terminal (25) is connected to the first secondary winding (51) and the second secondary terminal (25') is connected to the second secondary winding (53).

6. Power electronic converter (1) according to claim 1 or 2, wherein the double unit (31) has a low-voltage unit (9) and the transformer unit (7) has a secondary connection (25), wherein the one secondary connection (25) is connected to the one low-voltage unit (9).

7. Power electronic converter (1 ) according to claim 1 , wherein the double unit (31) comprises two transformer units (7), wherein the two second high-voltage converter units (13) of the double unit (31) are each connected at their outputs to one of the two transformer units (7).

8. Power electronic converter according to one of the preceding claims, wherein the high-voltage units (5) and / or the low-voltage units (9) each have a control unit (29) for controlling the high-voltage and / or low-voltage converter units (11, 13, 15).

9. Power electronic converter (1) according to one of the preceding claims, wherein the double unit (31) comprises a high-voltage control unit (29) for controlling the two high-voltage units (5).

10. Power electronic converter (1 ) according to one of claims 4 and 9, wherein the double unit (31) has a low voltage control unit (29) for controlling the two low voltage units (9).

11. Power electronic converter system (57) comprising a plurality of power electronic converter cells (3), wherein the plurality of power electronic converter cells (3) comprise: at least one high-voltage unit (5) comprising at least one first high-voltage converter unit (11) and at least one second high-voltage converter unit (13), at least one low-voltage unit (9) comprising at least one low-voltage converter unit (15), at least one transformer unit (7) having at least one primary connection (23) and at least one secondary connection (25), wherein at least one of the plurality of power electronic converter cells (3) has a power electronic converter (1) according to claims 1 to 10 with a double unit (31).

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