Transformer arrangement and method of voltage conversion

Abstract

A transformer arrangement (10) comprises first and second device sides (11, 12) and a transformer (13) having a first winding (14) coupled to the first device side (11) and a second winding (15) having first to fourth taps (17 to 20). The transformer arrangement (10) comprises a converter (22) coupling the first, second and third taps (17 to 19) to the second device side (12), a first filter circuit (34) coupling the first tap (17) to the third tap (19), and a second filter circuit (35) coupling the third tap (19) to the second tap (18).

Description

Technical Field

[0001] This disclosure relates to a transformer device and a method for voltage conversion. Background Technology

[0002] Transformer units perform AC-to-AC conversion. Since the number of windings on the first and second sides of the transformer is constant, the conversion rate is also constant. To change the conversion rate, an on-load tap changer (OLTC) can be used. However, OLTCs result in high manufacturing costs and can only be used to achieve different conversion rate values.

[0003] Document US 2013 / 0207471 A1 describes a power converter based on an estimated DC link unit. The power converter includes a transformer having a first winding and a second winding with four taps. Three taps are coupled to the output of the power converter via the estimated DC link unit and an output filter inductor.

[0004] Document US 2016 / 0099653 A1 describes a power flow controller with a fractional-rated back-to-back converter. The transformer has a secondary winding with four taps. Two of the four taps are coupled to the output of the device via the converter. Summary of the Invention

[0005] The aim is to provide transformer devices with high conversion efficiency flexibility and methods for voltage conversion.

[0006] This objective is achieved through the subject matter of the independent claim. Further improvements are described in the dependent claims.

[0007] A transformer device is provided, comprising first and second device sides, a transformer, a converter, and first and second filter circuits. The transformer includes a first winding coupled to the first device side and a second winding having first, second, third, and fourth taps. The converter couples the first, second, and third taps to the second device side. The first filter circuit couples the first tap to the third tap. The second filter circuit couples the third tap to the second tap.

[0008] Advantageously, the converter receives three voltages at its input side and can use these three voltages to generate a second voltage. The first voltage is connected at the first device side. The second voltage is connected at the second device side. The second voltage can be the output voltage. The second voltage can have multiple different values. The conversion rate of the transformer device can be controlled.

[0009] The first device side can be a high-voltage side, and the second device side can be a low-voltage side; the first voltage is higher than the second voltage. Alternatively, the first device side can be a low-voltage side, and the second device side can be a high-voltage side; the first voltage is lower than the second voltage.

[0010] The first device side can be the source side, and the second device side can be the load side. Therefore, the first device side can be coupled to a source such as a power grid, and the second device side can be coupled to a load such as a motor on another power grid.

[0011] Alternatively, the first device side can be the load side, and the second device side can be the source side. Therefore, the first device side can be coupled to the load, and the second device side can be coupled to the source.

[0012] In the improved transformer assembly, the converter includes: a first arm comprising a first number of units and a first terminal connected to a first tap; a second arm comprising a second number of units and a first terminal connected to a second tap; and a third arm comprising a third number of units and a first terminal connected to a third tap. Advantageously, the first, second, and third taps are each connected to separate arms. By controlling the three arms, the generation of a second voltage as a function of the voltage tapped at the tap can be tuned.

[0013] In the improvement, the transformer assembly includes a filter circuit system. The filter circuit system can be implemented as a low-pass filter. The filter circuit system couples the converter to the second device side. Advantageously, the filter circuit system achieves smoothing of the second voltage.

[0014] In the improved transformer assembly, the second terminal of the first bridge arm, the second terminal of the second bridge arm, and the second terminal of the third bridge arm are coupled to the first terminal on the second device side via a filter circuit system. Therefore, the first, second, and third bridge arms are connected to one terminal of the filter circuit system, and the other terminal of the filter circuit system is coupled to the first terminal on the second device side.

[0015] In the improvement of the transformer unit, the filter circuit system includes a capacitor element connected to the third tap. Additionally, the filter circuit system includes an inductor element.

[0016] In the improvement of the transformer assembly, the fourth tap of the second winding is coupled to the second assembly side. The fourth tap is connected to or coupled to the second terminal on the second assembly side.

[0017] In the improved transformer assembly, the first bridge arm includes a first LF section and a first HF section. The second bridge arm includes a second LF section and a second HF section. The third bridge arm includes a third HF section. The converter includes first and second internal filters. The first internal filter couples the node between the first LF section and the first HF section to a neutral point. The second internal filter couples the node between the second LF section and the second HF section to a neutral point. In this example, the third bridge arm may not have an LF section.

[0018] In the improvement of the transformer unit, the first, second, and third HF sections include units of type 1. The first and second LF sections include units of type 2. LF is an abbreviation for low frequency or low switching frequency, and HF is an abbreviation for high frequency or high switching frequency. The units of type 1 are configured to operate at a higher frequency than the units of type 2. The units of type 1 operate at a high switching frequency. The units of type 2 operate at a low switching frequency.

[0019] In the improved transformer assembly, the converter includes a fourth bridge arm comprising a fourth number of units and a first terminal connected to a third tap. The second terminal of the third bridge arm is connected to a node of the first bridge arm. The second terminal of the fourth bridge arm is connected to a node of the second bridge arm. The second terminals of the first and second bridge arms are coupled to a first terminal on the second assembly side. Advantageously, by using the third and fourth bridge arms, a second voltage can be generated with high flexibility.

[0020] In the improvement of the transformer assembly, the first bridge arm includes a first internal filter. The second bridge arm includes a second internal filter. Advantageously, the second voltage tapped at the first terminal on the second assembly side is smoothed by the first and second internal filters.

[0021] In the improved transformer assembly, the node of the first arm is located between the first LF section and the first HF section of the first arm. The node of the second arm is arranged between the second LF section and the second HF section of the second arm.

[0022] In the improvement of the transformer device, the third number of units is less than the first number of units and less than the second number of units. Advantageously, the voltage on the third arm is less than the voltage on the first arm and the voltage on the second arm. Compared with the first and second arms, the converter can be implemented with fewer units for the third arm. Advantageously, compared with a converter with three arms having the same number of units, the third number of units, which is less than the first number and less than the second number, results in lower losses and lower costs.

[0023] In the improvement of the transformer device, the first number of units is equal to the second number of units. Advantageously, the maximum voltage on the first arm is equal to the maximum voltage on the second arm.

[0024] The quantity of the first unit is, for example, greater than 1. The quantity of the second unit is, for example, greater than 1. The quantity of the third unit is, for example, greater than 1. The quantity of the fourth unit is, for example, greater than 1.

[0025] In improvements to transformer devices, the unit includes devices from the group comprising metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), reverse-conduction insulated-gate bipolar transistors (RC-IBGTs), thyristors, and two-mode insulated-gate transistors (BIGTs). Advantageously, the devices in this group allow the unit to be configured to be in an on- and off-state.

[0026] In the improvement of transformer devices, the thyristor can be one of the following: phase-controlled thyristor (PCT), bidirectional controllable thyristor (BCT), and integrated gate commutation thyristor (IGCT).

[0027] In the improvement of the transformer device, a first number of units in the first arm include at least units of a first type and units of a second type. A second number of units in the second arm include at least units of a first type and units of a second type. The units of the first type are implemented as high-frequency units, and the units of the second type are implemented as low-frequency units. The units of the first type and the units of the second type are implemented in different ways, that is, they include different devices, such as those listed above. The units of the first type are configured to operate at a higher frequency than the units of the second type. In the example, the low switching frequency or operating range of the low-frequency unit can be from 20 Hz to 1 kHz, or from 50 Hz to 600 Hz, or from 60 Hz to 500 Hz. In the example, the high switching frequency or operating range of the high-frequency unit can be from 0.4 kHz to 200 kHz, or from 0.6 kHz to 100 kHz. These are just examples of ranges. There may be overlap between the ranges of the high-frequency unit and the ranges of the low-frequency unit.

[0028] In improvements to transformer units, the first type of unit (also known as the HF unit) includes, for example, wide bandgap devices (abbreviated as WBG devices) and / or devices optimized for low switching losses. These devices can be transistors or thyristors.

[0029] In the improvement of transformer units, the second type of unit (also known as the LF unit) includes devices optimized for low conduction losses. These devices can be transistors or thyristors.

[0030] In the improvement, the transformer assembly includes a bypass switch that couples a first terminal on the second assembly side to one of a group including first, second, and third taps. The bypass switch can be used for short-circuit protection. The bypass switch may include a thyristor or another switch.

[0031] In the improvement, the transformer assembly includes a box in which the converter is arranged and a enclosure in which the transformer and the box are arranged. Advantageously, a cooling system is provided for both the converter and the transformer.

[0032] In the improved version, the transformer assembly includes a box in which the converter is arranged, a enclosure in which the transformer is arranged, and bushings coupling at least first, second, and third taps to the converter. Advantageously, the enclosure and the box are separate. The box is not inside the enclosure. Therefore, maintenance or replacement of the converter can be performed separately from maintenance or replacement of the transformer.

[0033] A method for voltage conversion is provided, the method comprising:

[0034] -Provide the first voltage to the first winding of the transformer.

[0035] - Voltage is generated at the first to fourth taps of the second winding of the transformer.

[0036] - A second voltage is provided by a converter coupled to the first, second, and third taps.

[0037] - The voltage between the first tap and the third tap is filtered by the first filter circuit, and

[0038] - The voltage between the third tap and the second tap is filtered by the second filter circuit.

[0039] Advantageously, the first filter circuit smooths the voltage between the first and third taps. Correspondingly, the voltage between the third and second taps is smoothed by the second filter circuit. The second voltage can be set to a predetermined value by controlling the converter. The first and second voltages are AC voltages.

[0040] Transformer devices are particularly suitable for voltage conversion methods. Therefore, the characteristics described in conjunction with the transformer device can be used in this method, and vice versa.

[0041] In development, the transformer unit implemented a power electronic AC-AC converter as an OLTC for transformer voltage regulation. Power electronics (sometimes called power electronic devices) are abbreviated as PE. The converter can be implemented as a power electronic converter, abbreviated as PE converter. The power electronic AC-AC converter topology shows benefits in on-load voltage regulation, replacing the traditional electromechanical OLTC of the transformer, thereby reducing transformer manufacturing costs and improving functionality. The transformer unit achieves regulation of the power transformer voltage and / or the power flow through the transformer, for example, through stepped or stepless voltage control. Attached Figure Description

[0042] The following description of the accompanying drawings, which illustrate examples or embodiments, further demonstrates and explains aspects of the transformer apparatus and the method for voltage conversion. Devices, apparatuses, circuits, and units having the same structure and effect are represented by equivalent reference numerals. The function of corresponding devices, apparatuses, circuits, and units in different drawings is not repeated for each of the following drawings.

[0043] Figure 1 , Figure 2A and Figure 2B An exemplary embodiment of the transformer device is shown;

[0044] Figures 3A to 3D An exemplary embodiment of the unit is shown, and Figure 3E and Figure 3F An exemplary embodiment of the filter circuit is shown;

[0045] Figure 4 and Figures 5A to 5D An example of the cell's pattern is shown;

[0046] Figure 6 , Figures 7A to 7C , Figure 8A , Figure 8B , Figure 9 , Figure 10 , Figure 11A and Figure 11B An exemplary embodiment of the transformer device is shown;

[0047] Figure 12 Another exemplary embodiment of a transformer device with three phases is shown;

[0048] Figure 13A and Figure 13B An exemplary embodiment of a transformer device with a housing is shown;

[0049] Figures 14A to 14D Different exemplary embodiments of the transformer device are shown; and

[0050] Figures 15A to 15C , Figures 16A to 16C , Figure 17A and Figure 17B An exemplary mode of a transformer device is shown. Detailed Implementation

[0051] Figure 1 An exemplary embodiment of a transformer assembly 10 is shown. The transformer assembly 10 includes first and second device sides 11, 12, and a transformer 13. The transformer 13 includes a first winding 14 and a second winding 15. The second winding 15 has first to fourth taps 17 to 20. The transformer assembly 10 includes a filter device 21 connected to the first to third taps 17 to 18. Additionally, the transformer assembly 10 includes a converter 22. The converter 22 may be implemented as a power electronic converter. The converter 22 is coupled to the first, second, and third taps 17 to 18 via the filter device 21. The transformer assembly 10 includes a filter circuit system 23 coupled to the converter 22 and coupled to the second device side 12. The second device side includes first and second terminals 24, 25. The first terminal 24 of the second device side 12 is coupled to the first, second, and third taps 17 to 19 via the filter circuit system 23, the converter 22, and the filter device 21. The second terminal 25 of the second device side is connected to the fourth tap 20. The filter circuit 23 may also be referred to as an output filter. The filter device 21 may include an electromagnetic interference filter, abbreviated as EMI filter. The filter device 21 may be referred to as an input filter.

[0052] A first voltage V1 is tapped at the first device side 11. A second voltage V2 is tapped at the second device side 12. The second voltage V2 is tapped between the first and second terminals 24 and 25. The first voltage V1 can be implemented as a high voltage, and the second voltage V2 can be implemented as a low voltage. Therefore, V1 > V2. The second voltage V2 can be supplied to the load. A minimum voltage V2min is tapped between the second tap 18 and the fourth tap 20. A differential voltage DV is tapped between the first terminal 24 and the second tap 18 on the second device side 12. A first current I1 flows through the first winding 14. A second current I2 flows through the second winding 15, specifically through the second terminal 25. The second current I2 can also be referred to as the load current.

[0053] exist Figure 1 In this transformer unit 10, input and output filters 21 and 23 are included. The converter 22 implements an on-load PE tap changer. Input and output filters 21 and 23 are provided according to the rated power and design requirements of the transformer unit 10 (including, for example, requirements for maximum harmonic content). In the case of each tap changer, filters 21 and 23 are designed using reactors, capacitors, and resistors. In the case of many tap changers, input capacitor 21 and output reactor are sufficient.

[0054] Figure 2A and Figure 2B An exemplary embodiment of the transformer device 10 is shown, which is Figure 1 A further improvement to the embodiment shown. The converter 22 includes first, second, and third bridge arms 31, 32, and 33. The first bridge arm 31 has a first terminal connected to a first tap 17. A second terminal of the first bridge arm 31 is coupled to a first terminal 24 of a second device side 12. The second bridge arm 32 has a first terminal connected to a second tap 18. A second terminal of the second bridge arm 32 is coupled to the first terminal 24 of the second device side 12. Correspondingly, the third bridge arm 33 has a first terminal connected to a third tap 19. A second terminal of the third bridge arm 33 is coupled to the first terminal 24 of the second device side 12. The converter 22 may also be referred to as a power electronic on-load tap changer AC-AC converter (abbreviated as PE OLTC AC-AC converter).

[0055] like Figure 2A As shown, the first bridge arm 31 includes a first quantity N1 of units 29, the second bridge arm 32 includes a second quantity N2 of units, and the third bridge arm 33 includes a third quantity N3 of units. The first quantity N1 may be equal to the second quantity N2. The third quantity N3 may be less than the first quantity N1 and less than the second quantity N2.

[0056] The transformer device 10 includes a first filter circuit 34 and a second filter circuit 35. The first and second filter circuits 34 and 35 form a filter device 21. The first and second filter circuits 34 and 35 can be referred to as input filters. Each of the first and second filter circuits 34 and 35 includes capacitors 36 and 37.

[0057] The second voltage V2 can be referred to as the output voltage, transformer output voltage, load voltage, or transformer LV output voltage. Continuous and rapid adjustment of the second voltage V2 can be achieved through… Figure 2A and Figure 2B The transformer unit 10 shown is used for implementation. Within design margins, the converter 22 allows for the elimination of the conventional stepper electromechanical OLTC and reduces transformer manufacturing costs by removing the regulating winding. By removing the regulating winding, transformer design can be improved to save on material and labor costs. This topology allows for simplified requirements on transformer design and the elimination of the electromechanical OLTC to provide at least one of the following: rapid continuous on-load voltage regulation; mitigation of voltage flicker; phase angle control of the second voltage V2 (the phase angle can vary within a specific range); and the modified converter unit can operate as a circuit breaker.

[0058] exist Figure 2A and Figure 2B The diagram shows a transformer device 10 that implements the PE OLTC AC / AC converter topology. Figure 2A The basic scheme (with unit 29) is shown, and Figure 2B A matrix scheme (with element 29) is shown. Figure 2B In the middle, the first bridge arm 31 includes a matrix 30 (which is in Figure 3C and Figure 3D (See explanation below). Accordingly, the second and third bridge arms 32 and 33 each include a matrix.

[0059] The converter design will depend on at least one of the following:

[0060] • Voltage and current requirements;

[0061] • Device voltage rating and device current rating;

[0062] • Design factors and margins; and / or

[0063] • Required reliability (redundancy).

[0064] Figures 3A to 3D An exemplary embodiment of the unit 29 and matrix 30 that can be used in the first to third bridge arms 31 to 33 is shown.

[0065] exist Figure 3A In this embodiment, unit 29 includes first and second devices 41 and 42, and a switch 40 (which may be referred to as a bypass switch). The first and second devices 41 and 42 are connected in series. The first and second devices 41 and 42 also form an anti-series device connection. The first and second devices 41 and 42 can be implemented as insulated-gate bipolar transistors (IGBTs). Alternatively, the first and second devices 41 and 42 are fabricated as metal-oxide-semiconductor field-effect transistors (MOSFETs). Unit 29 includes a buffer filter 43. The buffer filter 43 includes a capacitor. Alternatively, unit 29 can be implemented without a buffer filter.

[0066] exist Figure 3B In this context, unit 29 includes device 44. Device 44 is a semiconductor device based on Si or wide-bandgap (e.g., SiC) semiconductors, possessing both bipolar voltage capability and unidirectional current capability. Device 44 is implemented, for example, as a phase-controlled thyristor (PCT). Alternatively, Figure 3B The unit 29 shown includes first and second devices connected in parallel, for example in an anti-parallel circuit. Therefore, unit 29 is implemented by two anti-parallel devices.

[0067] exist Figure 3C and Figure 3DIn this matrix, matrix 30 includes units 29 connected in series and / or in parallel. Units 29 can be implemented as described above or as follows. Typically, different semiconductor device technologies can be used to implement units 29 and / or matrix 30: Si and SiC semiconductor materials, as well as insulated gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and integrated gate-commutated thyristors (IGCTs). For example, matrix 30 includes at least two units 29 connected in parallel.

[0068] Each bridge arm 31 to 33 includes power devices (IGBTs and / or MOSFETs) connected in anti-series, such as... Figures 3A to 3D As shown, this forms a switch that can operate under on-off conditions in two current directions and two blocking voltage polarities, such as... Figure 4 As shown.

[0069] exist Figure 2B and Figure 3C and Figure 3D The same concept is illustrated in the design of matrix 30 by using series and / or parallel connections of switches or units 29 to increase current and / or voltage converter requirements and / or improve system reliability. For example... Figure 4 As shown, matrix 30 also functions as an on-off switch in two current directions and two blocking voltage polarities.

[0070] exist Figure 3C In the matrix 30, there is a matrix arrangement of cells 30 with anti-series devices. The first, second, or third bridge arms 31 to 33 are series / parallel combinations of switches arranged in a matrix.

[0071] Unit 29 can be implemented as either a first type of unit 29' or a second type of unit 29". The first type of unit 29' can also be referred to as a high-frequency unit. The second type of unit 29" can be referred to as a low-frequency unit.

[0072] Unit 29 is implemented as a four-quadrant switch, abbreviated as 4QS.

[0073] The second type of unit 29” operates at low switching frequencies and can be implemented in the following manner:

[0074] - This is achieved by employing semiconductor devices based on Si or wide-bandgap (e.g., SiC) semiconductors, which possess both unipolar voltage capability and bidirectional current capability. Examples of such devices are IGBTs and MOSFETs, such as... Figure 3A As shown.

[0075] - This is achieved by employing semiconductor devices with bipolar voltage capability and unidirectional current capability based on Si or wide-bandgap (e.g., SiC) semiconductors. A phase-controlled thyristor (PCT) is an example of such a device.

[0076] - This is achieved by employing semiconductor devices with bipolar voltage and bidirectional current capabilities based on Si or wide-bandgap (e.g., SiC) semiconductors. A bidirectional controllable thyristor (BCT) is an example of such a device, such as... Figure 3B As shown.

[0077] The second type of unit 29” can be interconnected in the following ways: such as Figure 2A The series connection of unit 29" shown, or as Figure 3C and Figure 3D The matrix 30 shown is a unit 29” (connected in series, in parallel, or in a combination of series and parallel).

[0078] The first type of cell 29' operates at a high switching frequency (abbreviated as HF) and can be implemented by semiconductor devices with unipolar voltage capability and bidirectional current capability based on Si or wide-bandgap (e.g., SiC) semiconductors. Examples of such devices are IGBTs and MOSFETs, such as... Figure 3A As shown. The first type of unit 29' can be interconnected in the following ways: as Figure 2A The series connection of unit 29' shown, or as Figure 3C and Figure 3D The matrix 30 of such unit 29' is shown (connected in series, in parallel, or in a combination of series and parallel).

[0079] Figure 3E and Figure 3F An exemplary embodiment of the first filter circuit 34 is shown, which is Figure 2A and Figure 2B Further improvements to the illustrated embodiment. The second filter circuit 35, buffer filter 43, capacitor element 91, first and second internal filters 97, 98, and internal filter 102 (shown below) can be implemented as such as the first filter circuit 34. A capacitor filter similar to the first filter circuit 34 is indicated by the letter Fc in the figure.

[0080] The first filter circuit 34 is a capacitor filter, which can be implemented, for example, in the following manner:

[0081] • A single capacitor of 36, such as Figure 3E As shown.

[0082] • Capacitors connected in parallel.

[0083] • Capacitors connected in series.

[0084] • A matrix of series and parallel capacitors.

[0085] like Figure 3FAs shown, the first filter circuit 34 is, for example, a resistor / capacitor filter. The first filter circuit 34 includes a resistor 45. The resistor 45 is connected in series with the capacitor 36. All of the above can be combined with resistors 45 (or a resistor matrix) connected in series with each individual capacitor or with any combination (series, parallel, or series and parallel) of capacitors. The introduced resistors are useful for attenuating resonance between the capacitor(s) and the inductive elements connected to the first filter circuit 34 or to other capacitor filters.

[0086] Figure 4 An example of the pattern of the above-mentioned unit 29 or matrix 30 is shown, that is, the equivalent on-off switch of the various anti-series devices or units.

[0087] Figures 5A to 5D An example of the pattern of unit 29 as described above is shown. Figure 5A , Figure 5B , Figure 5C and Figure 5D The normal operating mode of the anti-series switch or unit 29 is shown. The switch and current path in the on state are highlighted with thick lines. The switch in the off state and the connection lines with no current or a small current are shown with normal lines.

[0088] Figure 6 An exemplary embodiment of the transformer assembly 10 is shown, which is a further improvement on the embodiment shown above. In both cases, the dimensions of the third arm 33 can be determined for the transformer's rated current and for a lower voltage than the other two arms (the first and second arms 31, 32). Under normal operating conditions, losses will be lower.

[0089] like Figure 6 As shown, the second voltage V2 can be adjusted within a certain voltage range according to the design and three different normal operating modes, such as... Figures 7A to 7C As shown. Depending on the desired value of the second voltage V2, one or both bridge arms will conduct. LV is an abbreviation for low voltage. HV is an abbreviation for high voltage.

[0090] exist Figure 6 The single-phase PE OLTC AC-AC converter 22 at the LV side is shown. Alternatively, converter 22 is connected to the HV side. For clarity, the input capacitor is omitted. Therefore, for clarity, in Figure 6 , Figures 7A to 7C , Figure 8A , Figure 8B , Figure 9 , Figure 10 , Figure 11A , Figure 11B , Figure 12 , Figure 13A and Figure 13B The filter device 21, the first and second filter circuit systems 34 and 35, and the filter circuit system 23 are omitted.

[0091] Figures 7A to 7C A mode of an exemplary embodiment of the transformer device 10 shown above is illustrated. Figures 7A to 7C The normal operating mode of the proposed on-load PE tap changer is shown in the figure.

[0092] exist Figure 7A In Mode 1, the first and third bridge arms 31 and 33 are active and switch alternately.

[0093] V2nom <V2<V2max

[0094] exist Figure 7B In Mode 2, the second and third bridge arms 32 and 33 are active and alternate between each other.

[0095] V2min <V2<V2nom

[0096] exist Figure 7C In Mode 3, the third bridge arm 33 is movable.

[0097] V2 = V2nom

[0098] V2 is the second voltage. V2min is the minimum value of the second voltage and is connected at the second tap 18. V2max is the maximum value of the second voltage and is connected at the first tap 17. V2nom is the nominal value of the second voltage and is connected at the third tap 19.

[0099] Figure 8A and Figure 8B An exemplary embodiment of the voltage and control scheme of the transformer assembly 10 is shown, which is a further improvement on the embodiment shown above. N1 is the number of windings in the first winding 14. N2 is the number of windings in the second winding 15 from the third tap 19 to the fourth tap 20. n It is a ratio. k is a factor less than 1. The third tap 19 is located between the first tap 17 and the second tap 18 at the second winding 15. The winding of the second winding 15 couples the third tap 19 to the second tap 18. The number of these windings is, for example, N2·k or N2·k2 (e.g., Figure 10 (As shown). An additional winding of the second winding 15 couples the third tap 19 to the first tap 17. Multiple additional windings, such as N2·k or N2·k1, may also be present. An additional winding of the second winding 15 couples the second tap 18 to the fourth tap 20. V 2a This is the voltage between the second tap 18 and the fourth tap 20. V 2bThis is the voltage connected between the third tap 19 and the second tap 18. V 2c It is the voltage connected between the first tap 17 and the second tap 18. V1 n This is the nominal value of the first voltage, V1. V2 n (=V2nom) is the nominal value of the second voltage V2. V2 min (=V2min) is the minimum value of the second voltage. V2 max (=V2max) is the maximum value of the second voltage.

[0100] Several possible control schemes exist. A constant switching frequency f can be implemented. sw Simple voltage control under the condition that, for a given desired value V of the second voltage V2, ref Select the operating mode and duty cycle (mode 1 to mode 3) and δ = t on / T sw To obtain the expected value V ref As described below, the second voltage V2 can be adjusted within half a cycle of the mains frequency. δ is the duty cycle. T sw It refers to the duration of a period as a cycle. t on It is a period of conduction between bridge arms 31 and 33.

[0101] Figure 9 Further exemplary embodiments of the transformer assembly 10 are shown, which are further improvements to the embodiments shown above. The transformer assembly 10 includes a bypass switch 50. The bypass switch 50 is implemented by two switches 51, 52, such as two thyristors connected in an anti-parallel circuit. The bypass switch 50 couples the first terminal 24 of the second device side 12 to another node, such as a first tap 17, a second tap 18, or a third tap 19. To reduce cost and size, the converter 22 is protected from external short-circuit currents. During a fault, the anti-parallel thyristors of the bypass converter can be used as follows: Figure 9 The implementation is shown. Terminal X can be connected to node A, B, or C (depending on the design). Therefore, bypass switch 50 or more bypass switches are configured for short-circuit protection (thyristors or other technologies can be used).

[0102] As described above, the basic objectives of the transformer assembly 10 (with OLTC PE AC-AC converter 22) are, for example, rapid and continuous voltage regulation of the transformer; and / or mitigation of voltage flicker.

[0103] The transformer unit 10 will be designed based on its rated power, voltage, and system short-circuit current. For example, the main considerations are:

[0104] - The converter voltage rating will depend on the voltage regulation range (ΔV)max Requirements for rated current;

[0105] The device current rating of the -PE AC-AC OLTC converter 22 should withstand the system short-circuit current;

[0106] - Different combinations of semiconductor device types can be used: IGBT, dual-mode insulated gate transistor (BIGT), MOSFET, IGCT, and the semiconductor material can be Si or SiC;

[0107] - Redundant switches (and additional necessary devices) that allow converter operation in the event of some switch failures.

[0108] The number of redundant switches depends on reliability / availability requirements;

[0109] - Appropriate control over reliable switching during normal operation;

[0110] - Depends on the outer loop controller of the regulation function;

[0111] - Rapid response to fault current (bypassing of short-circuit current (SCC));

[0112] - Protection against voltage pulses (e.g., due to lightning or switching transients in the power grid); and / or

[0113] - The converter can also be implemented with low-cost conventional air cooling or two-phase cooling concepts (no conventional liquid cooling environment required).

[0114] Further variations of the transformer assembly 10 are shown in the following figures:

[0115] Figure 10 An exemplary embodiment of the transformer device 10 is shown, which is a further improvement on the embodiment shown above. Depending on requirements and design, the second voltage V2 can be controlled between a maximum value (V2max = V2nom + DV1) and a minimum value (V2min = V2nom - DV). The upper and lower limits can be different (DV1 ≠ DV), such as... Figure 10 As shown. In this case, the first quantity N1 units 29 can be different from the second quantity N2 units 29. Figure 10 In this embodiment, transformer unit 10 realizes a single-phase AC-ACPE converter as an OLTC connected at the LV side (or it can be connected at the HV side).

[0116] Figure 11A and Figure 11B An exemplary embodiment of the transformer device 10 is shown, which is a further improvement on the embodiment shown above. The transformer device 10 can be as follows: Figure 11AThe connection to ground 54 or the reference potential terminal, as explained and shown, or as... Figure 11B As shown, it is floating. The transformer assembly 10 can have a grounded PE converter or a floating PE OLTC AC-AC converter. The first terminal 24 of the second device side 12 ( Figure 11A ) or the second terminal 25 of the second device side 12 ( Figure 11B Connect to ground 54.

[0117] Figure 12 Further exemplary embodiments of a three-phase transformer assembly 10 are shown, which are further improvements to the embodiments shown above. The transformer assembly 10 includes an additional transformer 55 corresponding to the transformer 13. The additional transformer 55 includes first and second windings 56, 57. The second winding 57 includes first to fourth taps 58 to 61. Furthermore, the transformer assembly 10 includes an additional converter 62 coupled to the first, second, and third taps 58 to 60. Additionally, the second side 12 of the transformer assembly 10 includes a third terminal 63. The terminals of the additional converter 62 are connected to a first terminal 24 of the second assembly side 12.

[0118] Additionally, the transformer assembly 10 includes an additional transformer 70 having first and second windings 71, 70. The second winding 72 includes first to fourth taps 73 to 76. The transformer assembly 10 includes an additional converter 77 connected to the first, second, and third taps 73 to 75. Terminals of the additional converter 77 are connected to the first terminal 24 of the second assembly side 12. The fourth terminal 78 of the second assembly side 12 is connected to the fourth tap 76. Therefore, at the second assembly side 12, three phases a, b, and c can be tapped at the second, third, and fourth terminals 25, 36, and 78. The neutral phase n can be tapped at the first terminal 24 of the second assembly side 12.

[0119] A third voltage V3 is supplied to the first winding 56 of another transformer 55. An additional converter 62 generates a fourth voltage V4. A fifth voltage V5 is supplied to the first winding 71 of an additional transformer 70. An additional converter 77 generates a sixth voltage V6. The voltage differences DV4, DV6 and the minimum voltages V4min, V6min can be tapped at the other converter 62 and the additional converter 77.

[0120] The converter 22 for single-phase transformers can be used with three-phase transformer banks, or three-phase transformers in any of the following connections: star-delta YD, delta-star DY, delta-delta DD, or star-star YY, or others, and connections at the HV or LV side. For example... Figure 12As shown, the three-phase connection (YY) of transformer assembly 10 is implemented on the LV side. Other three-phase connections (such as YD, DY, and DD) are also possible. The connections of converters 22, 52, and 77 on the HV side are also possible.

[0121] Figure 13A and Figure 13B An exemplary embodiment of a transformer assembly 10 having a housing 80 is shown, which is a further improvement on the embodiment shown above. Figure 13A As shown, the transformer assembly 10 includes a housing 80. A converter 22 is inserted into the housing 80. Additionally, first and second filter circuit systems 34, 35 and filter circuit system 23 (not shown) can also be inserted into the housing 18. The transformer assembly 10 includes a case 81. A transformer 13 is inserted into the case 81. Additionally, the housing 80 is also inserted into the case 81.

[0122] like Figure 13B As shown, box 80 is not inserted into enclosure 81. Box 80 is outside enclosure 81. Therefore, enclosure 81 does not have box 80. Transformer assembly 10 includes bushings 82 to 84 that couple enclosure 81 to box 80. Bushings 82 to 84 couple first to third taps 17 to 18 to converter 22.

[0123] The OLTC AC-AC PE converter 22 can be constructed as a separate unit and connected to the transformer 13 in the substation. It can also be integrated inside the transformer box 81 or assembled in an external box 80, which can be referred to as a container, as separate units. Figure 13A and Figure 13B The modular backpack solution shown. Figure 3A In this configuration, transformer 13 and converter 22 are installed in the same enclosure 81. Figure 13B In this design, transformer 13 and converter 22 are implemented using a backpack modular solution.

[0124] Figures 14A to 14D Different exemplary embodiments of the transformer device 10 are shown, which are further improvements to the embodiments shown above. Figure 1 , Figure 2A and Figure 2B The PE converter 22 shown represents one way of implementing basic voltage regulation by employing three transformer taps 17 to 19. However, the same function can be implemented by other circuit variations, which will be briefly described in the following paragraphs and figures. For example, in Figures 3A to 3F The symbols used to describe and define circuit variations are summarized below.

[0125] Figure 14A An exemplary embodiment of the transformer device 10 is shown, which is a further improvement upon the above-described embodiment. Figure 14A In the middle, transformer device 10 represents Figure 1 , Figure 2A and Figure 2B The changes to the initial circuit are shown in the diagram. Figure 14A In the diagram, each bridge arm 31 to 33 is represented by the 4QS ​​symbol (in...). Figures 3A to 3D (as defined and described in the text), and adds filter device 21 and filter circuit system 23. First and second filter circuits 34 and 35 form filter device 21, also referred to as input filter.

[0126] The filter device 21 is primarily capacitive. For example... Figure 3F As shown, the filter device 21 may include a resistive element that is introduced to attenuate electrical resonance.

[0127] The filter circuit system 23 that couples the converter 22 to the second side 12 of the transformer assembly 10 is a low-pass filter. The filter circuit system 23 includes an inductor 90 and a capacitor 91, as shown in Figures 2E and 2F (it is possible to introduce a resistor to attenuate oscillations between the inductor 90 and capacitor 91 in the filter circuit system 23). This is only one possible implementation of the filter. Other implementations are also possible. Furthermore, the lower end of the capacitor 91 in the filter circuit 23 is connected to the neutral point NP. The neutral point NP is connected to the third tap 19. Alternatively, this terminal can be connected to the upper terminal of the top auxiliary winding or to the lower terminal of the bottom auxiliary winding, meaning that this terminal can be connected to the first or second taps 17, 18.

[0128] exist Figure 14A In this context, the circuit change indicates Figure 2A The diagram shows a supplementary circuit for a low-pass LC filter 23 used to filter out the switching harmonics of the converter 22. The capacitor element 91 and the first and second filters 34, 35 can be implemented as the first filter 34, which... Figure 3E and Figure 3F as well as Figure 3E and 3F The description explains this and is indicated by the letter Fc. Each of the first to third bridge arms 31 to 33 is implemented with at least one four-quadrant switch, their combination... Figures 3A to 3D Explanation is provided and indicated by the letter 4QS.

[0129] The first bridge arm 31 is composed of unit 29 (e.g., as shown in the example). Figure 3A and Figure 3B As shown), the series circuit of unit 29 (such as...) Figure 2A (as shown) or matrix 30 of unit 29 (as shown) Figure 2B , Figure 3C and Figure 3D(As shown) is implemented. The second and third arms 32 and 33 are implemented as, for example, the first arm 31.

[0130] Figure 14B An exemplary embodiment of the transformer device 10 is shown, which is a further improvement of the above embodiment. Figure 14B The circuit changes shown are based on Figure 14A The circuit changes are shown in the diagram. However, the upper and lower bridge arms, namely the first and second bridge arms 31 and 32, are divided into two parts; notably, one part 92 and 94 operate at a low switching frequency (abbreviated as LF), while the other part 93 and 95 operate at a high switching frequency (abbreviated as HF). Therefore, the first bridge arm 31 includes a first LF part 92 and a first HF part 93. The second bridge arm 32 includes a second LF part 94 and a second HF part 95. The third bridge arm 33 includes a third HF part 96. The first and second LF parts 92 and 94 include second-type units 29'. Furthermore, the first, second, and third HF parts 93, 95, and 96 include first-type units 29'. LF is an abbreviation for low frequency, and HF is an abbreviation for high frequency. The HF part can be referred to as the first-type part. The LF part can be referred to as the second-type part. One or more HF parts are implemented differently from one or more LF parts. The third bridge arm 33, for example, does not have an LF part.

[0131] Regarding the operation, this change is related to Figure 2A The difference in the initial circuit shown is that the first, second, and third HF sections 93, 95, and 96 regulate the second voltage V2, while the first and second LF sections 92 and 94 clamp the first and second HF sections 93 and 95 to one of the auxiliary windings. Therefore, all switching operations are performed by the first, second, and third HF sections 93, 95, and 96, while the first and second LF sections 92 and 94 remain in the ON state. In one example, one of the first and second LF sections 92 and 94 is in the ON state, while the other is in the ON state. Figures 15A to 15C The operation of this transformer device 10 is briefly described in the text.

[0132] The HF or LF section can be accessed through unit 29 (e.g., as shown in the image). Figure 3A and Figure 3B As shown), the series circuit of unit 29 (such as...) Figure 2A (as shown) or matrix 30 of unit 29 (as shown) Figure 2B , Figure 3C and Figure 3D As shown in the diagram, this is achieved. In Figures 14B to 14D In the letter 4QS[HF], the HF part is indicated by the letter 4QS[LF] and the LF part is indicated by the letter 4QS[LF].

[0133] This change and Figure 2A , Figure 2B The difference in the initial circuit shown is that the separation of the bridge arms in the LF and HF sections provides an opportunity to minimize total losses by employing different devices. Notably, devices optimized for low conduction losses (e.g., IGBTs, BIGTs, PCTs, BCTs at 4.5 and 6.5 kV voltage levels) can be used in the LF sections 92 and 94, while devices optimized for low switching losses (e.g., Si-based IGBTs, SiC-based IGBTs, SiC-based MOSFETs at 1.2 and 1.7 kV voltage levels) are used in the HF sections 93, 95, and 96.

[0134] This change is similar in the following ways. Figure 1 , Figure 2A and Figure 2B The initial circuit shown in the figure has the same total voltage rating for the semiconductor devices, and if the second voltage V2 must be equal to the nominal voltage V2nom, then the third bridge arm 33 (referred to as the middle bridge arm) provides a path with low conduction loss. The filter circuit system 23, referred to as the output L-Fc filter, can be connected to the neutral point NP or another terminal, such as the second tap 18 (referred to as the upper terminal of the top auxiliary winding) or the first tap 17 (referred to as the lower terminal of the bottom auxiliary winding).

[0135] Converter 22 includes first and second internal filters 97 and 98. The first and second internal filters 97 and 98 are implemented, for example, as a first filter circuit 34. The first and second internal filters 97 and 98 can be low-pass filters. The first internal filter 97 couples the node between the first LF portion 92 and the first HF portion 93 of the first bridge arm 31 to the neutral point NP. Correspondingly, the second internal filter 98 couples the node between the second LF portion 94 and the second HF portion 95 of the second bridge arm 32 to the neutral point NP. The internal filters 97 and 98 can be introduced to reduce voltage stress on the HF portion during switching operations (e.g., as a buffer). Figure 14B As shown by the dashed line, internal filters 97 and 98 are optional. Figure 14B In this configuration, converter 22 divides the first and second bridge arms 31, 32 into two parts: one operating at a low switching frequency [LF] and the other operating at a high switching frequency [HF]. The input and output capacitors can be replaced with capacitors connected in series with resistors (see [link]). Figure 3E and Figure 3F ).

[0136] Figure 14C An exemplary embodiment of the transformer device 10 is shown, which is a further improvement upon the above embodiment. For example... Figure 14CAs shown, the third bridge arm 33 couples the third tap 19 to a node of the first bridge arm 31. This node is located between the first LF portion 92 and the first HF portion 93 of the first bridge arm 31. The first number of units N1 in the first bridge arm 31 is greater than 1. The node of the first bridge arm 31 is coupled to a first terminal of the first bridge arm 31 via at least one unit, and is coupled to a second terminal of the first bridge arm 31 via at least one unit. The third bridge arm 33 includes an LF portion 99. The converter 22 includes a fourth bridge arm 100 that couples the third tap 19 to a node of the second bridge arm 32. This node is arranged between the second LF portion 94 and the second HF portion 95 of the second bridge arm 32. The second number of units N2 in the second bridge arm 32 is greater than 1. The node of the second bridge arm 32 is coupled to a first terminal of the second bridge arm 32 via at least one unit, and is coupled to a second terminal of the second bridge arm 32 via at least one unit. The fourth bridge arm 100 includes an LF portion 101.

[0137] Figure 14C The transformer device 10 shown is based on the structure of an active neutral point clamping converter.

[0138] Similar to the previous circuit variations, there are two types of components: one type operates at a low switching frequency [LF] and the other at a high switching frequency [HF]. HF sections 93 and 95 perform voltage regulation, while LF sections 92, 94, 99, and 101 clamp HF sections 93 and 95 to one of the first or second taps 17 and 18 (achieved by the auxiliary winding). Therefore, all switching operations are performed by HF sections 93 and 95, while LF sections 92, 94, 99, and 101 remain continuously on. Figures 16A to 16C The operation of this circuit change is briefly described in the text. For example... Figures 16A to 16C As shown, if the second voltage V2 must be equal to the nominal voltage V2nom, the parallel connection of the two LF-HF branches can provide a path with low conduction loss. Converter 22 may include an internal filter 102, which can be implemented as the first filter circuit 43 (in...). Figure 3E or Figure 3F (as shown in the diagram). However, if an optional internal filter 102 is present, the activation of this path is carefully performed to avoid inrush current due to the discharge of the capacitors of the internal filter 102 (e.g., activation can be performed at the zero-crossing point of the voltage on the internal filter 102).

[0139] Similar to Figure 14BThe circuit changes provide opportunities to minimize total losses by employing different devices. For example, devices optimized for low conduction losses (e.g., 4.5kV and 6.5kV voltage ratings of IGBTs, BIGTs, PCTs, and BCTs) can be used in the LF sections 92, 94, 99, and 101, while devices optimized for low switching losses (e.g., 1.2kV and 1.7kV voltage ratings of Si-based IGBTs, SiC-based IGBTs, and SiC-based MOSFETs) can be used in the HF sections 93 and 95.

[0140] The total voltage rating of the semiconductor devices in this circuit is higher than... Figure 14A and Figure 14B The circuit varies the voltage rating. The filter circuit system 23 (referred to as the output L-Fc filter) can be connected to the neutral point NP or other terminals, such as the second tap 18 (upper terminal of the top auxiliary winding) or the first tap 17 (lower terminal of the bottom auxiliary winding), or to one of the midpoints between the upper or lower LF and HF sections. An optional internal filter 102 can be introduced (in... Figure 14C (Represented by dashed lines), used to reduce voltage stress on HF components during switching operations (e.g., as a buffer). Figure 14C In this circuit, the changes are based on an active neutral point clamping structure. The HF sections 93 and 95 perform voltage regulation, while the LF sections 92, 94, 199, and 101 clamp the HF sections 93 and 95 to either of the two auxiliary windings for voltage Δv.

[0141] Figure 14D An exemplary embodiment of the transformer device 10 is shown, which is a further improvement of the above embodiment. Figure 14D The transformer device 10 shown is based on Figure 14C The transformer assembly has been modified, but the placement of the HF and LF sections has been swapped. Specifically, the HF section is now positioned closer to taps 17 to 19 (i.e., closer to the auxiliary winding). Figure 14C Compared to the circuit changes, this change has no effect on the total voltage rating of the semiconductor device. However, it affects the internal filters 97 and 98. The converter 22 includes first and second internal filters 97 and 98. The first internal filter 97 is coupled to the first tap 17 via the first HF portion 93 of the first bridge arm 31, and to the third tap 19 via the third bridge arm 33. The first internal filter 97 is coupled to the first terminal 24 of the second device side 12 via the first LF portion 92 of the first bridge arm 31. The third bridge arm 33 includes an HF portion 103.

[0142] Accordingly, the second internal filter 98 is coupled to the second tap 18 via the second portion 95 of the second bridge arm 32, and to the third tap 19 via the fourth bridge arm 100. The fourth bridge arm 100 includes the HF portion 104. The second internal filter 98 is coupled to the first terminal 24 of the second device side 12 via the second LF portion 94 of the second bridge arm 33. The first and second internal filters 97 and 98 each include inductor elements 90 and 90' and capacitor elements 91 and 91'. The first and second internal filters 97 and 98 are arranged close to the HF portions 93, 95, 103, and 104 for filtering harmonics of the HF portions 93, 95, 103, and 104. The first and second internal filters 97 and 98 replace the filter circuit system 23 or the output L-Fc filter.

[0143] One terminal of the first internal filter 97 is connected to point B. One terminal of the second internal filter 98 is connected to point A. The potentials at points A and B can float relative to the neutral phase NP, and in this example, can be equal to Δv. Therefore, with Figure 14C Compared to the circuit changes, a larger input capacitor may be required. Furthermore, the aforementioned terminals of the L-Fc filter connected to points A and B can alternatively be connected to the first and second taps 17, 18 (the lower terminal of the bottom auxiliary winding and the upper terminal of the top auxiliary winding) or both connected to the neutral point or neutral phase NP.

[0144] The first filter circuit 34 includes first and second filter elements 106 and 107 interconnected by point B in a series connection. The second filter circuit 35 includes third and fourth filter elements 108 and 109 interconnected by point A in a series connection.

[0145] Regarding the operation of this change, only one HF and one LF section are active at a time. It is worth noting that one of the HF sections is performing voltage regulation, while the corresponding LF section clamps the output of the HF section to the second terminal 24 of the second device side 12. Figure 17A and 17B The operation of this circuit change is briefly described below. The internal filter 102 is optional (in...). Figure 14B (represented by dashed lines in the middle), and can be introduced to reduce voltage stress on HF components during switching operations (e.g., as a buffer).

[0146] exist Figure 14D In this embodiment, the transformer unit 10 is based on an active neutral point clamping structure, but differs from the previous one in the positions of the LF and HF sections. Figure 14C The circuit changes in the converter 22 are as follows: the HF section that performs voltage regulation is placed closer to the auxiliary winding; the LC filters 97 and 98 required for filtering HF harmonics are placed closer to the HF section of the converter 22.

[0147] In the proposals and designs described in this disclosure, at least one of the following features is implemented: the power electronic AC-AC converter topology allows for transformer voltage and flicker mitigation. The converter 22 can be assembled using anti-series connected Si / SiC-based devices (such as IGBTs, BIGTs, and / or MOSFETs). The control strategy includes three operating modes (see...). Figures 7A to 7C The converter 22 is assembled in the same housing 81 as the transformer 13, or as a modular backpack solution outside the housing 81 of the transformer 13. Figure 13A and 13B (or as a separate unit). Figures 14A to 14D The circuit changes presented in the middle were implemented with Figure 1 , Figure 2A and Figure 2B The circuit shown in the diagram has the same function.

[0148] Advantageously, the transformer assembly 10 offers benefits such as being faster, cheaper, and safer. The transformer assembly 10 replaces the conventional stepper electromechanical OLTC; it simplifies the design requirements for the transformer 13 (simplified transformer design); it reduces transformer manufacturing costs (mechanical design, fewer additional windings); it reduces power electronic losses compared to existing technologies; and it achieves and improves the compactness of a unified transformer-PE block compared to conventional OLTC solutions. The transformer assembly 10 includes extended transformer functionality (i.e., flicker mitigation).

[0149] Figures 15A to 15C It shows Figure 14B An example of the pattern of transformer device 10. Figure 14B The circuit operation is illustrated in the diagram. For example... Figure 15A As shown, the second voltage V2 should be in the range of 0.9 to 1 p.u. (pu represents the second voltage V2 provided in the unit system). The second LF portion 94 of the second bridge arm 32 remains on. The second HF portion 95 of the second bridge arm 32 and the third HF portion 96 of the third bridge arm 33 switch.

[0150] exist Figure 15B In this configuration, the second voltage V2 should be within the range of 1.0 to 1.1 pu. The first LF section 92 of the first bridge arm 31 remains continuously conducting. The first HF section 93 of the first bridge arm 31 and the third HF section 96 of the third bridge arm 33 switch.

[0151] exist Figure 15C In the middle, the second voltage V2 should be approximately 1.0 pu. The third HF section 96 of the third bridge arm 33 is turned on. The output filter impedance is interposed in the current path.

[0152] Figures 16A to 16C It shows Figure 14C An example of the mode of a transformer device. For example... Figure 16A As shown, the second voltage V2 should be in the range of 0.9 to 1 p.u. The upper auxiliary winding, with second and third taps 18 and 19, is connected to the HF sections 93 and 95 via two continuously conducting LF sections 94 and 99. Switching the HF sections 93 and 95 adjusts the second voltage V2.

[0153] exist Figure 16B In this configuration, the second voltage V2 should be in the range of 1.0 to 1.1 pu. The lower auxiliary winding, with first and third taps 17 and 19, is connected to the HF sections 93 and 95 via two continuously conducting LF sections 94 and 101. Switching the HF sections 93 and 95 adjusts the second voltage V2.

[0154] exist Figure 16C In this configuration, the second voltage V2 should be approximately 1.0 pu. Low conduction losses are achieved through parallel connection of the LF and HF sections. Care should be taken when implementing the activation of this path to avoid short-circuiting the dummy capacitor. The input and output capacitors can be replaced by capacitors connected in series with resistors (see [link to relevant documentation]). Figure 3E and Figure 3F ).

[0155] Figure 17A and Figure 17B It shows Figure 14D An exemplary model of the transformer device 10. The input and output capacitors can be replaced by capacitors connected in series with resistors (see [reference]). Figure 3E and Figure 3F ).

[0156] like Figure 17A As shown, the second voltage V2 should be in the range of 0.9 to 1 p.u. The HF portions 95 and 104 of the second and fourth bridge arms 32 and 100 are switched to regulate the second voltage V2. The second LF portion 94 of the second bridge arm 32 remains continuously on.

[0157] exist Figure 17B In this configuration, the second voltage V2 should be within the range of 1.0 to 1.1 pu. The HF sections 93 and 103 of the first and third bridge arms 31 and 33 switch to regulate the second voltage V2. The first LF section 92 of the first and third bridge arms 31 remains continuously on.

[0158] As described Figures 1 to 17B The embodiments shown represent exemplary embodiments of improved transformer devices and methods for voltage conversion; therefore, they do not constitute a complete list of all embodiments according to improved transformer devices and methods for voltage conversion. Actual transformer devices and methods may differ from the illustrated embodiments, for example, in terms of apparatus, devices, circuits, units, and voltage.

[0159] This patent application claims priority to European Patent Application 20200063.4, the disclosure of which is incorporated herein by reference.

[0160] Further aspects of this disclosure are described in detail below. These aspects are listed for ease of reference to features of the other aspects.

[0161] 1. A transformer device, comprising:

[0162] -First and second device sides (11, 12),

[0163] - A transformer (13) having a first winding (14) coupled to a first device side (11) and a second winding (15) having first to fourth taps (17 to 20),

[0164] - A converter (22) that couples the first, second, and third taps (17 to 19) to the second device side (12),

[0165] - A first filter circuit (34) that couples a first tap (17) to a third tap (19), and

[0166] - A second filter circuit (35) that couples a third tap (19) to a second tap (18).

[0167] 2. According to the transformer device in aspect 1,

[0168] The converter (22) includes:

[0169] - First bridge arm (31), the first bridge arm includes a first number of units (29) and a first terminal connected to a first tap (17),

[0170] - Second bridge arm (32), which includes a second number of units (29) and a first terminal connected to a second tap (18), and

[0171] - The third bridge arm (33) includes a third number of units (29) and a first terminal connected to the third tap (19).

[0172] 3. According to the transformer device in aspect 2,

[0173] The transformer device (10) includes a filter circuit system (23), and

[0174] The second terminal of the first bridge arm (31), the second terminal of the second bridge arm (32), and the second terminal of the third bridge arm (33) are coupled to the first terminal (24) of the second device side (12) via the filter circuit system (23).

[0175] 4. According to the transformer device in aspect 3,

[0176] The filter circuit system (23) includes a capacitor element (91) connected to the third tap (19).

[0177] 5. According to the transformer device in aspect 2,

[0178] The converter (22) includes a fourth bridge arm (100), which includes a fourth number of units (29) and a first terminal connected to a third tap (19).

[0179] The second terminal of the third bridge arm (33) is connected to the node of the first bridge arm (31).

[0180] The second terminal of the fourth bridge arm (100) is connected to the node of the second bridge arm (32), and

[0181] The second terminal of the first bridge arm (31) and the second terminal of the second bridge arm (32) are coupled to the first terminal (24) of the second device side (12).

[0182] 6. According to the transformer device in aspect 5,

[0183] The first bridge arm (31) includes a first internal filter (97), and the second bridge arm (32) includes a second internal filter (98).

[0184] 7. A transformer device according to any one of aspects 2 to 6,

[0185] The third number of units (29) is less than the first number of units (29) and less than the second number of units (29).

[0186] 8. A transformer assembly according to any one of aspects 2 to 7,

[0187] Among them, the first quantity of unit (29) is equal to the second quantity of unit (29).

[0188] 9. A transformer assembly according to any one of aspects 2 to 8,

[0189] Unit (29) includes devices in the group comprising metal-oxide-semiconductor field-effect transistors, insulated-gate bipolar transistors, thyristors and dual-mode insulated-gate transistors.

[0190] 10. A transformer device according to any one of aspects 2 to 9,

[0191] The first number of units (29) of the first bridge arm (31) includes at least units of a first type (29') and units of a second type (29”), and

[0192] The second number of units (29) of the second bridge arm (32) includes at least the first type of unit (29') and the second type of unit (29”).

[0193] 11. A transformer device according to any one of aspects 1 to 10,

[0194] The transformer assembly (10) includes a bypass switch (50) that couples the first terminal (24) of the second assembly side (24) to a tap in a group including first, second and third taps (17 to 19).

[0195] 12. A transformer device according to any one of aspects 1 to 11,

[0196] The transformer device (10) includes:

[0197] -A box (80) containing a converter (22) and

[0198] -The box (81) contains a transformer (13) and a box (80).

[0199] 13. A transformer device according to any one of aspects 1 to 11,

[0200] The transformer device (10) includes:

[0201] -A box (80) containing a converter (22) is arranged therein.

[0202] -Including a box (81) containing a transformer (13), and

[0203] - Sleeves (82 to 84) that couple at least the first, second and third taps (17 to 19) to the converter (22).

[0204] 14. A method for voltage conversion, comprising:

[0205] -Provide a first voltage (V1) to the first winding (14) of the transformer (13),

[0206] - A voltage is generated at the first to fourth taps (17 to 19) of the second winding (15) of the transformer (13).

[0207] - A second voltage (V2) is provided by a converter (22) coupled to the first, second, and third taps (17 to 19).

[0208] - The voltage between the first tap (17) and the third tap (19) is filtered by the first filter circuit (34), and

[0209] - The voltage between the third tap (19) and the second tap (18) is filtered by the second filter circuit (35).

[0210] List of reference numerals

[0211] 10 Transformer Unit

[0212] 11 First device side

[0213] 12 Second device side

[0214] 13 Transformers

[0215] 14 First Winding

[0216] 15 Second winding

[0217] 17 First tap

[0218] 18 First tap

[0219] 19 Third tap

[0220] 20 Fourth tap

[0221] 21 Filter Device

[0222] 22 Converters

[0223] 23 Filter Circuit System

[0224] 24 First terminal

[0225] 25 Second terminal

[0226] Unit 29

[0227] 30 matrix

[0228] 31 First bridge arm

[0229] 32 Second bridge arm

[0230] 33 Third bridge arm

[0231] 34 First Filter Circuit

[0232] 35 Second Filter Circuit

[0233] 36, 37 capacitors

[0234] 40 switches

[0235] Devices 41 and 42

[0236] 43 Buffer Filter

[0237] 44 Devices

[0238] 45 resistor

[0239] 50 Bypass switch

[0240] Switches 51 and 52

[0241] 54 locations

[0242] 55 Other Transformers

[0243] 56, 57 windings

[0244] 58 to 61 taps

[0245] 62 Other converters

[0246] 63 Third terminal

[0247] 70 Additional Transformer

[0248] 71, 72 windings

[0249] 73 to 76 taps

[0250] 77 Additional Converters

[0251] 78 Fourth terminal

[0252] 80 boxes

[0253] 81 boxes

[0254] 82 to 84 casing

[0255] 90, 90' inductor element

[0256] 91, 91' capacitor elements

[0257] 92 First LF Part

[0258] 93 Part 1 HF

[0259] 94 Part 2 LF

[0260] 95 Part 2 HF

[0261] 96 Part 3HF

[0262] 97 First Internal Filter

[0263] 98 Second Internal Filter

[0264] 99 LF section

[0265] 100 Fourth bridge arm

[0266] 101 LF section

[0267] 102 Internal Filter

[0268] 103, 104HF sections

[0269] 106 to 109 filter elements

[0270] Points A and B

[0271] a, b, c phases

[0272] Differential voltage of DV, DV1, and DV4

[0273] DV6 differential voltage

[0274] I1 First Current

[0275] I2 Second Current

[0276] N, n neutral phase

[0277] NP neutral point

[0278] V1 First Voltage

[0279] V2 Second Voltage

[0280] V2min, V4min minimum voltage

[0281] V6min minimum voltage

[0282] V3 to V6 voltage

Claims

1. A transformer device (10), comprising: - First device side and second device side (11, 12). - Transformer (13), the transformer having a first winding (14) coupled to the first device side (11) and a second winding (15) having first to fourth taps (17 to 20). - Converter (22), which couples the first tap, the second tap and the third tap (17 to 19) to the second device side (12). - A first filter circuit (34) that couples the first tap (17) to the third tap (19), and - Second filter circuit (35), which couples the third tap (19) to the second tap (18). The converter (22) includes: - First bridge arm (31), the first bridge arm includes a first number of units (29) and a first terminal connected to the first tap (17), - Second bridge arm (32), the second bridge arm includes a second number of units (29) and a first terminal connected to the second tap (18), and - The third bridge arm (33) includes a third number of units (29) and a first terminal connected to the third tap (19). The third number of units (29) is less than the first number of units (29) and less than the second number of units (29). The converter (22) includes a fourth bridge arm (100), which includes a fourth number of units (29) and a first terminal connected to the third tap (19). The second terminal of the third bridge arm (33) is connected to a node of the first bridge arm (31). Wherein, the second terminal of the fourth bridge arm (100) is connected to the node of the second bridge arm (32), and The second terminal of the first bridge arm (31) and the second terminal of the second bridge arm (32) are coupled to the first terminal (24) of the second device side (12). The node of the first bridge arm (31) is located between the first LF portion (92) and the first HF portion (93) of the first bridge arm (31). The nodes of the second bridge arm (32) are arranged between the second LF portion (94) and the second HF portion (95) of the second bridge arm (32). Wherein, the first HF portion and the second HF portion include portions of a first type, and the first LF portion and the second LF portion include portions of a second type; and The portion of the first type is configured to operate at a higher frequency than the portion of the second type.

2. The transformer device according to claim 1, in, The transformer device (10) also includes a filter circuit system (23).

3. The transformer device according to claim 2, in, The filter circuit system (23) includes a capacitor element (91) connected to the third tap (19).

4. The transformer device according to claim 1, in, The first bridge arm (31) includes a first internal filter (97), and the second bridge arm (32) includes a second internal filter (98).

5. The transformer device according to any one of claims 1 to 4, in, The first number of units (29) is equal to the second number of units (29).

6. The transformer device according to any one of claims 1 to 4, in, Unit (29) includes devices in the group comprising metal-oxide-semiconductor field-effect transistors, insulated-gate bipolar transistors, thyristors and dual-mode insulated-gate transistors.

7. The transformer device according to any one of claims 1 to 4, in, The first number of units (29) of the first bridge arm (31) includes at least units of a first type (29') and units of a second type (29"). Wherein, the second number of units (29) of the second bridge arm (32) includes at least a first type of unit (29') and a second type of unit (29"), and The first type of unit (29') is configured to operate at a higher frequency than the second type of unit (29").

8. The transformer device according to any one of claims 1 to 4, in, The transformer device (10) includes a bypass switch (50) that couples the first terminal (24) of the second device side (12) to one of a group including the first tap, the second tap and the third tap (17 to 19).

9. The transformer device according to any one of claims 1 to 4, in, The transformer device (10) includes: - A box (80), in which the converter (22) is arranged, and - Box (81), in which the transformer (13) and the box (80) are arranged.

10. The transformer device according to any one of claims 1 to 4, in, The transformer device (10) includes: - Box (80), in which the converter (22) is arranged. - Box (81), in which the transformer (13) is arranged, and - A sleeve (82 to 84) that couples at least the first tap, the second tap and the third tap (17 to 19) to the converter (22).

11. A method for voltage conversion, comprising: - Provide a first voltage (V1) to the first winding (14) of the transformer (13). - Voltage is generated at the first to fourth taps (17 to 19) of the second winding (15) of the transformer (13). - A second voltage (V2) is provided to the second device side (12) by a converter (22) coupled to the first tap, the second tap and the third tap (17 to 19). - The voltage between the first tap (17) and the third tap (19) is filtered by the first filter circuit (34), and - The voltage between the third tap (19) and the second tap (18) is filtered by the second filter circuit (35). The converter (22) includes: - First bridge arm (31), the first bridge arm includes a first number of units (29) and a first terminal connected to the first tap (17), - Second bridge arm (32), the second bridge arm includes a second number of units (29) and a first terminal connected to the second tap (18), and - The third bridge arm (33) includes a third number of units (29) and a first terminal connected to the third tap (19). The third number of units (29) is less than the first number of units (29) and less than the second number of units (29). The converter (22) includes a fourth bridge arm (100), which includes a fourth number of units (29) and a first terminal connected to the third tap (19). The second terminal of the third bridge arm (33) is connected to a node of the first bridge arm (31). Wherein, the second terminal of the fourth bridge arm (100) is connected to the node of the second bridge arm (32), and The second terminal of the first bridge arm (31) and the second terminal of the second bridge arm (32) are coupled to the first terminal (24) of the second device side (12). The node of the first bridge arm (31) is located between the first LF portion (92) and the first HF portion (93) of the first bridge arm (31). The nodes of the second bridge arm (32) are arranged between the second LF portion (94) and the second HF portion (95) of the second bridge arm (32). Wherein, the first HF portion and the second HF portion include portions of a first type, and the first LF portion and the second LF portion include portions of a second type; and The portion of the first type is configured to operate at a higher frequency than the portion of the second type.

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