WO2022148545A1

WO2022148545A1 - Transformer and electronic device

Info

Publication number: WO2022148545A1
Application number: PCT/EP2021/050281
Authority: WO
Inventors: Simon WALTON
Original assignee: Abb Schweiz Ag
Priority date: 2021-01-08
Filing date: 2021-01-08
Publication date: 2022-07-14

Abstract

Embodiments of present disclosure relates to a transformer and an electronic device comprising the transformer. The transformer comprises a delta-connected transforming device comprising windings disposed around cores for phases of alternative current (AC) power and configured to transform AC input voltages to AC output voltages. The transformer further comprises a zigzag device comprising windings disposed around the cores and coupled to the delta-connected transforming device to form, a neutral, connection for zero sequence currents of the transformer. With the transformer of the embodiments, it may achieve reduced VA while forming a low impedance zero sequence path.

Description

TRANSFORMER AND ELECTRONIC DEVICE

TECHNICAL FIELD

[0001] Example embodiments of the present disclosure generally relate to electronic devices, in partially to transformers and electronic devices comprising the transformers.

BACKGROUND

[0002] Electronic power converters or inverters are commonly used to generate three- phase voltages for powering commercial and industrial loads. One of the economic configurations for an electronic inverter involves active synthesis of three voltages measured from line to line (3 wires). The three-wire connection permits delivery of positive and negative sequence currents in a three-wire load. In many applications, however, it is necessary to generate a neutral voltage reference which has a low impedance to the zero sequence currents. This is often required in low voltage applications.

[0003] Several approaches have been proposed to meet the requirement. For example, a two-stage configuration comprising an auto transformer aid a zigzag transformer or reactor separated from the auto transformer has been proposed. However, this approach causes increased overall cost and size for the electronic devices. Other approaches, such as US patent No. 7,969,265, propose to embed a star transformer and a zigzag transformer into a single three-phase transformer. However, this may increase complexity in construction, leading to potential security risks.

SUMMARY

[0004] Example embodiments of the present disclosure propose a solution of transformers and electronic devices comprising the transformers.

[0005] In a first aspect, it is provided a transformer. The transformer comprises a delta- connected transforming device comprising windings disposed around cores for phases of alternative current (AC) power and configured to transform AC input voltages to AC output voltages. The transformer further comprises a zigzag device comprising windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer.

[0006] In a second aspect, it is provided an electronic device comprising the transformer of the first aspect,

[0007] In a third aspect, it is provided a method for manufacturing a transformer. The method comprises providing a delta-connected transforming device comprising windings disposed around cores for phases of alternative current (AC) power and configured to 5 transform AC input voltages to AC output voltages. The method further comprises providing a zigzag device comprising windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer.

10008] According to the embodiments of the present disclosure, the solution according 10 to embodiments of the present disclosure may achieve reduced volt-ampere (VA) while forming a low impedance zero sequence path,

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Through the following detailed descriptions with reference to the accompanying 15 drawings, the above and other objectives, features and advantages of the example embodiments disclosed herein will become more comprehensible. In the drawings, several example embodiments disclosed herein will be illustrated in an example and in a non-limiting manner, wherein:

[0010] Fig, 1 illustrates a conventional transformer;

20 [0011] Fig. 2 illustrates a phasor diagram for the conventional transformer of Fig. 1 ;

[0012] Fig. 3 illustrates an environment where example embodiments of the present disclosure can be implemented;

[0013] Fig. 4 illustrates a transformer in accordance with some example embodiments of the present disclosure;

[0014] Fig, 5 illustrates a phasor diagram for the transformer of Fig. 4;

[0015] Fig. 6 illustrates a transformer in accordance with some example embodiments of the present disclosure;

[0016] Fig, 7 illustrates a phasor diagram for the transformer of Fig. 6;

[0017] Fig. 8 illustrates a transformer in accordance with some example embodiments of

50 the present disclosure;

[0018] Fig. 9 illustrates a phasor diagram for the transformer of Fig. 8; and

[0019] Fig. 10 illustrates a flowchart of a method for manufacturing the transformer in accordance with some example embodiments of the present disclosure.

[0020] Throughout the drawings, the same or corresponding reference symbols refer to the same or corresponding parts.

DETAILED DESCRIPTION

[0021] The subject matter described herein will now be discussed with reference to several example embodiments. These embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the subject matter described herein, rather than suggesting any limitations on the scope of the subject matter.

[0022] The term “comprises” or “includes” and its variants are to be read as open terms that mean “includes, but is not limited to.” The term “or” is to be read as “and/or” unless the context clearly indicates otherwise. The term “based on” is to be read as “based at least in part on.” The term “being operable to” is to mean a function, an action, a motion or a state can be achieved by an operation induced by a user or an external mechanism. The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment.” The term “another embodiment” is to be read as “at least one other embodiment.”

[0023] Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Furthermore, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. In the description below, like reference numerals and labels are used to describe the same, similar or corresponding parts in the Figures. Other definitions, explicit and implicit, may be included below. In addition, electrical components, such as “resistor”, “capacitor”, “inductor” and “winding” may be implemented in various manners, and may include one or more elements without changing electrical nature.

[0024] As describe above, conventional transformers for generating three-phase voltages may suffer from significant cost and/or size or complexity in construction. Fig. 1 illustrates a conventional transformer, and Fig. 2 illustrates a phasor diagram for the conventional transformer of Fig. 1. The main winding is connected as a zigzag set with a star neutral, and the boost windings connected in series with the main windings are also connected as a zigzag set, so that the magneto motive force (MMF) generated by zero sequence currents in the windings sum to zero and create no associated flux.

[0025] Depending on connection of the zigzag boost winding, the transformer can generate a step-up or step-down voltage, with or without phase shift. If different voltage connections are needed, connections need to be arranged to ensure that both the boost windings in each phase are equally adjusted, making the tapping arrangement complex. [0026] Embodiments herein are directed to a novel configuration that combines a delta- connected transforming device and a zigzag device into a single transformer. The configuration may be implanted in various manners to achieve a lower cost than the conventional two-stage configuration, and may be suitable for multiple voltage taps. Other features and advantages will be described hereinafter with reference to the embodiments. [0027] Fig. 3 illustrates an environment where example embodiments of the present disclosure can be implemented. An electronic device 100 is provided to serve as an AC power supply. In an embodiment, the electronic device 100 is an uninterrupted power supply (UPS). Although the embodiments of transformers will be described below with reference to the environment of UPS, it is only for illustration without suggesting limiting scopes of the embodiments herein. The transformers can be applied to other AC power supplies, such as frequency converters.

[0028] The electronic device 100 comprises an energy saving device 10, such as a battery or a bank of capacitors, to store electrical energy. For example, when the main AC power supply is available, it supplies AC power to the AC load and the electronic device 100. The electronic device 100 may rectify the AC power into DC power, such that the energy saving device 10 may store the electrical energy.

[0029] In case that the main AC power supply to the load is interrupted or fails, the electronic device 100 acts as a backup AC power supply to supply power to the load. Specifically, the energy saving device 10 provides direct current (DC) power to the inverter 20 of the electronic device 100, and the inverter 20 converts the DC power to AC power. The AC voltages from the inverter 20 may be not suitable for the AC load in a low voltage system, and a transformer 30 is required to transform the AC voltages to suitable voltages. [0030] In some cases, the output voltage requirements for the AC load are close to the AC output voltage of inverter, and there is no requirement for galvanic isolation . However, there is still a need to match the nominal output AC voltage of the inverter (around 350V rms line to line) which has allowance for battery voltage variation to the required voltage of AC load ranging from 220V to 690V.

(0031) The electronic device 100 further comprises a transformer 30 to receive the converted AC power from the inverter 20. The transformer 30 is configured to transform AC input voltages of the received AC power to appropriate AC output voltages suitable for the load. In an embodiment, the AC power from the inverter 20 is three-phase AC power. In this case, the AC input voltages comprise three AC voltages for the three phases, respectively. Accordingly, the AC output voltages also comprise three AC voltages for the three phases, respectively.

[0032] hi the low voltage system which has a voltage in the range of 220V to 480V to the AC load, it needs a neutral path for the load that may need to continuously support even greater currents than the phase paths without introducing excessive voltage drop. As such, there are four terminals for the AC load in the transformer, including three terminals for the AC connections of three-phase and a terminal for the neutral terminal for the neutral path. Although the inverter 20 and the transformer 30 are illustrated to be separate components, this is only for the illustration without suggesting any limitation to the scopes herein, in another embodiment, the transformer 30 may be incorporated into the inverter 20 as a part of the inverter 20. The transformer 30 herein is especially advantageous, when small voltage corrections, such as a correction in a range of 10% to 40%, are required to optimize the inverter 20 and batery preferred voltages.

[0033] Fig. 4 illustrates a transformer 32 in accordance with some example embodiments of the present disclosure. The transformer 32 is a specific implementation of the transformer 30 of Fig. 3. The transformer 32 comprises a delta-connected transforming device and a zigzag device. The delta-connected transforming device comprises windings disposed around cores for phases of AC power and configured to transform AC input voltages to AC output voltages. The zigzag device comprises windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer. Although Fig. 4 shows a specific configuration of delta-connected auto-transformer together with an incorporated zigzag structure, this is only for illustration without suggesting any limitation to the scopes herein. Other configurations of delta-connected auto-transformer together with an incorporated zigzag structure are possible, as shown in Figs. 6-9.

[0034] In Fig. 4, the delta-connected transforming device comprises a first transforming unit for a first phase, a second transforming unit for a second phase and a third transforming unit for a third phase. The first transforming unit comprises a first core, and a first winding LI 11 and a second winding LI 12 around the first core. The first winding LI 11 comprises a first terminal coupled to a first AC connection terminal Us and a second terminal coupled to a second AC connection terminal Up. The second winding LI 12 comprises a first terminal coupled to the second AC connection terminal Up and a second terminal.

[0035] The second transforming unit comprises a second core, and a third winding L 121 and a fourth winding LI 22 around the second core. The third winding LI 21 comprises a first terminal coupled to a third AC connection terminal Vs and a second terminal coupled to a fourth AC connection terminal Vp and the second terminal of the second winding LI 12. The fourth winding LI 22 comprises a first terminal coupled to the fourth AC connection terminal Vp and a second terminal.

[0036] The third transforming unit comprises a third core, and a fifth winding LI 31 and a sixth winding L132 around Ac third core. The fifth winding L131 comprises a first terminal coupled to a fifth AC connection terminal Ws and a second terminal coupled to a sixth AC connection terminal Wp and the second terminal of the fourth winding LI 22, The sixth winding LI 32 comprises a first terminal coupled to the sixth AC connection terminal Wp and a second terminal coupled to the second AC connection terminal Up. [00371 The zigzag device comprises a first zigzag unit, a second zigzag unit and a third zigzag unit. The first zigzag unit comprises a seventh winding L 113 and an eighth winding LI 14 around the first core. The seventh winding LI 13 comprises a first terminal, and a second terminal coupled to a neutral terminal N for the neutral connection. The eighth winding LI 14 comprises a first terminal and a second terminal coupled to the fourth AC connection terminal Vp.

[0038] The second zigzagunit comprises a ninth winding LI23 and a tenth winding LI 24 around the second core. The ninth winding L 123 comprises a first terminal coupled to the first terminal of the eighth winding LI 14 and a second terminal coupled to the neutral terminal N. The tenth winding comprises a first terminal and a second terminal coupled to the sixth AC connection terminal Wp.

[0039) The third zigzag unit comprises an eleventh winding LI 33 and a twelfth winding L134 around the third core. The eleventh winding L133 comprises a first terminal coupled to the first terminal of the tenth winding LI 24 and a second terminal coupled to the neutral terminal N. The twelfth winding comprises a first terminal coupled to the first terminal of the seventh winding LI 13 and a second terminal coupled to the second AC connection terminal Up. The configuration as shown in Fig. 4 may be used to generate a neutral connection for a three-wire (neutral-less) inverter connection, without the need to use a full isolation delta-star transformer or combine multiple transformers, such as an auto transformer plus a zig-zag reactor.

[0040] Fig. 5 illustrates a phasor diagram for the transformer 32 of Fig. 4. The transformer 32 is configured as a delta connected auto-transformer to achieve the voltage matching requirement for the positive and negative sequence voltage. Depending on the connections, the transformer 32 may be configured to increase or decrease AC voltages. The zig-zag windings on the same transformer limbs provides a low impedance to the zero sequence currents.

[0041] In the transformer 32, the configuration involves 4 windings per phase with at least two different wire sizes. Also, additional voltage taps could be connected to the boost windings. In the embodiment, the boost winding is arranged to produce a phase lead and an increase in voltage. Alternatively, it could also be arranged to produce a phase lag. In some other embodiments, the boost winding produces a decrease in voltage. The boost leg could also be center tapped to provide an option of an increase and decrease in voltage, for example an output at 220V and 480V from a primary supply of 350V.

[0042] As compared to the conventional transformers of star-delta configuration, the transformer 32 may have lower VA rating, and the transformer 32 is more cost effective due to the fact that it does not need to support both the maximum voltage and the maximum current. Specifically, only the boost winding of the transformer 32 needs to carry the full current, and the voltage it supports is only the delta (boost) voltage, causing a reduced VA requirement. In addition, the transformer 32 may have more compact size, and provides a lower zero sequence impedance and better regulation to the neutral current loads.

[0043] As compared to the conventional complex zigzag auto transformers where a tap is needed per phase for the zig and the zag boost windings, the transformer 32 may comprise only one boost winding connected in the delta limb. As such, the transformer 32 can support multiple tap voltage with only one tap per phase per voltage. This could permit a rationalization of transformers over the product range, and may be well suited to multiple voltage taps. [0044] Fig. 6 illustrates a transformer 34 in accordance with some example embodiments of the present disclosure. The transformer 34 is a specific implementation of the transformer 30 of Fig. 3. The transformer 34 comprises a delta-connected transforming device and a zigzag device. The delta-connected transforming device comprises windings disposed around cores for phases of AC power and configured to transform AC input voltages to AC output voltages. The zigzag device comprises windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer. Although Fig. 6 shows a specific configuration of delta-connected auto-transformer together with an incorporated zigzag structure, this is only for illustration without suggesting any limitation to the scopes herein. Other configiirations of delta-connected auto-transformer together with an incorporated zigzag structure are possible.

[0045] The delta-connected transforming device comprises a first transforming unit, a second transforming unit and a third transforming unit. The first transforming unit comprises a first core, and a first winding L211 , a second winding L212 and a third winding L213 around the first core. The first winding L211 comprises a first terminal coupled to a first AC connection terminal Us and a second terminal coupled to a second AC connection terminal Up. The second winding L212 comprises a first terminal coupled to the second AC connection terminal Up and a second terminal. The third winding L213 comprises a first terminal coupled to the second terminal of the second winding L212 and a second terminal.

[0046] The second transforming unit comprises a second core, a fourth winding L221, and a fifth winding L222 and a sixth winding L223 around the second core. The fourth winding L221 comprises a first terminal coupled to a third AC connection terminal Vs and a second terminal coupled to a fourth AC connection terminal Vp. The fifth winding L222 comprises a first terminal coupled to the fourth AC connection terminal Vp and a second terminal. The sixth winding comprises a first terminal coupled to the second terminal of the fifth winding L222, and a second terminal coupled to the second AC connection terminal Up.

[0047] The third transforming unit comprises a third core, and a seventh winding L231 , an eighth winding L232 and a ninth winding L233 around the third core. The seventh winding L231 comprise a first terminal coupled to a fifth AC connection terminal Ws, and a second terminal coupled to a sixth AC connection terminal Wp and the second terminal of the third winding L213. The eighth winding comprises a first terminal coupled to the sixth AC connection terminal Wp and a second terminal The ninth winding L233 comprises a first terminal coupled to the second terminal of the eighth winding L231 and a second terminal coupled to the fourth AC connection terminal Vp,

[0048] The zigzag device comprises a tenth winding L214 around the first core, an eleventh winding L224 around the second core, and a twelfth winding L234 around the third core. The tenth winding L214 comprises a first terminal coupled to the second terminal of the fifth winding L222, and a second terminal coupled to a neutral terminal N for the neutral connection. The eleventh winding L224 comprises a first terminal coupled to the second terminal of the eighth winding L232, and a second terminal coupled to the neutral terminal N. The twelfth winding 234 comprises a first terminal coupled to the second terminal of the second winding L212 and a second terminal coupled to the neutral terminal N.

[0049] Fig. 7 illustrates a phasor diagram for the transformer 34 of Fig. 6. The transformer 34 is configured as a delta connected auto-transformer to achieve the voltage matching requirement for the positive and negative sequence voltage. Depending on the connections, the transformer 34 may be configured to increase or decrease AC voltages. The zig-zag windings on the same transformer limbs provides a low impedance to the zero sequence currents.

[0050] In the transformer 34, additional voltage taps could be connected to the boost windings. Analogously to the transformer 32, the boost winding is arranged to produce a phase lead and an increase in voltage. Alternatively, it could also be arranged to produce a phase lag. In some other embodiments, the boost winding could produce a decrease in voltage. The boost leg could also be center tapped to provide an option of an increase and decrease in voltage, for example an output at 220V and 480V from a primary supply of 350V.

[0051] As compared to the conventional transformers of star-delta configuration, the transformer 34 may have lower VA rating, and the transformer 34 is more cost effective. In addition, the transformer 34 can support multiple tap voltage with only one tap per phase per voltage. This could permit a rationalization of transformers over the product range, and may be well suited to multiple voltage taps. As compared to the transformer 32 of Fig. 4, the transformer 34 uses a tap connection on the delta lime to act as a part of the zig-zag connection. This may cause an easier construction.

[0052] Fig. 8 illustrates a transformer 36 in accordance with some example embodiments of the present disclosure. The transformer 36 is a specific implementation of the transformer 30 of Fig. 3. The transformer 36 comprises a delta-connected transforming device and a zigzag device. The delta-connected transforming device comprises windings disposed around cores for phases of AC power and configured to transform AC input voltages to AC output voltages. The zigzag device comprises windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer. Although Fig. 8 shows a specific configuration of delta-connected auto-transformer together with an incorporated zigzag structure, this is only for illustration without suggesting any limitation to the scopes herein. Other configurations of delta-connected auto-transformer together with an incorporated zigzag structure are possible.

[0053] The delta-connected transforming device comprises a first transforming unit, a second transforming unit and a third transforming unit. The first transforming unit comprises a first core, and a first winding L31 1 and a second winding L312 around the first core. The first winding L311 comprises a first terminal coupled to a first AC connection terminal Us and a second terminal coupled to a second AC connection terminal Up. The second winding L312 comprises a first terminal coupled to the second AC connection terminal Up and a second terminal.

[0054] The second transforming unit comprises a second core, and a third winding L321 and a fourth winding L322 around the second core. The third winding L321 comprises a first terminal coupled to a third AC connection terminal Vs and the second terminal of the first winding L31 1 , and a second terminal coupled to a fourth AC connection terminal Vp. The fourth winding L322 comprises a first terminal coupled to the fourth AC connection terminal Vp and the second terminal of the third winding L321, and a second terminal. [0055] The third transforming unit comprises a third core, and a fifth winding L331 and a sixth winding L332 around the third core. The fifth winding L331 comprises a first terminal coupled to a fifth AC connection terminal Ws and the second terminal of the fourth winding L322, and a second terminal coupled to the sixth AC connection terminal Wp. The sixth winding L332 comprises a first terminal coupled to the sixth AC connection terminal Wp and the second terminal of the fifth winding L331, and a second terminal coupled to the first AC connection terminal Us and the first terminal of the first winding L311.

[0056] The zigzag device comprises a seventh winding L3I3 around the first core, an eighth winding L323 around the second core, and a ninth winding L333 around the third core. The seventh winding L313 comprises a first terminal coupled to the sixth AC connection terminal Wp and a second terminal coupled to a neutral terminal N for the neutral connection. The eighth winding L323 comprises a first terminal coupled to the second AC connection terminal Up and a second terminal coupled to the neutral terminal N. The ninth winding L333 comprises a first terminal coupled to the fourth AC connection terminal Vp, and a second terminal coupled to the neutral terminal N.

[0957] Fig. 9 illustrates a phasor diagram for the transformer 36 of Fig. 8. The transformer 36 is configured as a delta connected auto-transformer to achieve the voltage matching requirement for the positive and negative sequence voltage. Depending on the connections, the transformer 36 may be configured to increase or decrease AC voltages. The zig-zag windings on the same transformer limbs provides a low impedance to the zero sequence currents.

[0058] In the transformer 36, additional voltage taps could be connected to the boost windings. Analogously to the transformers 32 and 34, the boost winding is arranged to produce a phase lead and an increase in voltage. Alternatively, it could also be arranged to produce a phase lag. In some other embodiments, the boost winding could produce a decrease in voltage. The boost leg could also be center tapped to provide an option of an increase and decrease in voltage, for example an output at 220V and 480V from a primary supply of 350V.

[0059] In an embodiment, the transformer 36 is configured to transform with a ratio of about V3 . The term “about” herein refers to a variation of ±10%, preferably a variation of ±5%. Such a ratio is well matched to a 600V or 220V system operating from an AC voltage of near 350V. In some embodiments, the delta-connected transforming device is configured to transform the AC input voltage in a range of 330V- 390V to the AC output voltage in a first range of 190V-225V or in a second range of 570V-675V. Alternatively, the delta-connected transforming device is configured to transform the AC input voltage in the first range of 190V-225V or in the second range of 570V-675V to the AC output voltage in the range of 330V- 390V.

P [0060] As compared to the conventional transformers of star-delta configuration, the transformer 36 may have lower VA rating, and the transformer 34 is more cost effective. In addition, the transformer 36 can support multiple tap voltage with only one tap per phase per voltage. This could permit a rationalization of transformers over the product range, and may be well suited to multiple voltage taps. As compared to the transformers 32 and 34, the transformer 36 comprises 3 windings per phase. This may reduce cost for the transformer, and simplify connections and constructions.

(0061 ] Fig. 10 illustrates a flowchart of a method 1000 for manufacturing the transformer in accordance with some example embodiments of the present disclosure. The transformer of Fig. 10 may be any of the transformers 30, 32, 34 and 36 in an embodiment. Thus, the features described with reference to Figs. 4-9 may be applied to the method 900 of Fig. 10. [00621 In 1002, it is provided a delta-connected transforming device comprising windings disposed around cores for phases of AC power and configured to transform AC input voltages to AC output voltages. In 1004, it is provided a zigzag device comprising windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer.

(0063) Hereinafter, some example implementations of the subject matter described herein will be listed.

[0064] Item 1. It is provided a transformer. The transformer comprises a delta- connected transforming device and a zigzag device. The delta-connected transforming device comprises windings disposed around cores for phases of AC power and configured to transform AC input voltages to AC output voltages. The zigzag device comprises windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer.

[0065] Item 2. Hie transformer of Item 1 , wherein the delta-connected transforming device comprises a first transforming unit, a second transforming unit and a third transforming unit. The first transforming unit comprises a first core of the cores; a first winding around the first core, comprising a first terminal coupled to a first AC connection terminal and a second terminal coupled to a second AC connection terminal; and a second winding around the first core, comprising a first terminal coupled to the second AC connection terminal and a second terminal. The second transforming unit comprises a second core of the cores; a third winding around the second core, comprising a first terminal coupled to a third AC connection terminal and a second terminal coupled to a fourth AC connection terminal and the second terminal of the second winding; and a fourth winding around the second core, comprising a first terminal coupled to the fourth AC connection terminal and a second terminal. The third transforming unit comprises a third core of the cores; a fifth winding around the third core, comprising a first terminal coupled to a fifth AC connection terminal and a second terminal coupled to a sixth AC connection terminal and the second terminal of the fourth winding; and a sixth winding around the third core, comprising a first terminal coupled to the sixth AC connection terminal and a second terminal coupled to the second AC connection terminal.

[0066] Item 3. The transformer of Item 1 or 2, wherein the zigzag device comprises a first zigzag unit, a second zigzag unit and a third zigzag unit. The first zigzag unit comprises a seventh winding around the first core, comprising a first terminal and a second terminal coupled to a neutral terminal for the neutral connection; and an eighth winding around the first core, comprising a first terminal and a second terminal coupled to the fourth AC connection terminal . The second zigzag unit comprises a ninth winding around the second core, comprising a first terminal coupled to the first terminal of the eighth winding and a second terminal coupled to the neutral terminal; and a tenth winding around the second core, comprising a first terminal and a second terminal coupled to the sixth AC connection terminal. The third zigzag unit comprises an eleventh winding around the third core, comprising a first terminal coupled to the first terminal of the tenth winding and a second terminal coupled to the neutral terminal; and a twelfth winding around the third core, comprising a first terminal coupled to the first terminal of the seventh winding and a second terminal coupled to the second AC connection terminal.

[0067] Item 4. The transformer of any of Items 1-3, wherein the delta-connected transforming device comprises a first transforming unit, a second transforming unit and a third transforming unit. The first transforming unit comprises a first core of the cores; a first winding around the first core, comprising a first terminal coupled to a first AC connection terminal and a second terminal coupled to a second AC connection terminal; a second winding around the first core, comprising a first terminal coupled to the second AC connection terminal and a second terminal; and a third winding around the first core, comprising a first terminal coupled to the second terminal of the second winding and a second terminal. The second transforming unit comprises a second core of the cores; a fourth winding around the second core, comprising a first terminal coupled to a third AC connection terminal and a second terminal coupled to a fourth AC connection terminal; a fifth winding around the second core, comprising a first terminal coupled to the fourth AC connection terminal and a second terminal; and a sixth winding around the second core, comprising a first terminal coupled to the second terminal of the fifth winding and a second terminal coupled to the second AC connection terminal. The third transforming unit comprises a third core of the cores; a seventh winding around the third core, comprising a first terminal coupled to a fifth AC connection terminal and a second terminal coupled to a sixth AC connection terminal and the second terminal of the third winding; an eighth winding around the third core, comprising a first terminal coupled to the sixth AC connection terminal and a second terminal; and a ninth winding around the third core, comprising a first terminal coupled to the second terminal of the eighth winding and a second terminal coupled to the fourth AC connection terminal.

[0068] Item 5. The transformer of any of Items 1-4, wherein the zigzag device comprises a tenth winding around the first core, comprising a first terminal coupled to the second terminal of the fifth winding and a second terminal coupled to a neutral terminal for the neutral connection; an eleventh winding around the second core, comprising a first terminal coupled to the second terminal of the eighth winding and a second terminal coupled to the neutral terminal; and a twelfth winding around the third core, comprising a first terminal coupled to the second terminal of the second winding and a second terminal coupled to the neutral terminal.

[0069] Item 6. The transformer of any of Items 1-5, wherein the delta-connected transforming device comprises a first transforming unit, a second transforming unit, and a third transforming unit. The first transforming unit comprises a first core of the cores; a first winding around the first core, comprising a first terminal coupled to a first AC connection terminal and a second terminal coupled to a second AC connection terminal; and a second winding around the first core, comprising a first terminal coupled to the second AC connection terminal and a second terminal. The second transforming unit comprises a second core of the cores; a third winding around the second core, comprising a first terminal coupled to a third AC connection terminal and the second terminal of the first winding, and a second terminal coupled to a fourth AC connection terminal ; and a fourth winding around the second core, comprising a first terminal coupled to the fourth AC connection terminal and the second terminal of the third winding, and a second terminal. The third transforming unit comprises a third core of the cores; a fifth winding around the third core, comprising a first terminal coupled to a fifth AC connection terminal and the second terminal of the fourth winding, and a second terminal coupled to the sixth AC connection terminal; a sixth winding around the third core, comprising a first terminal coupled to the sixth AC connection terminal and the second terminal of the fifth winding, and a second terminal coupled to the first AC connection terminal and the first terminal of the first winding.

[0070] Item 7. The transformer of any of Items 1 - 6, wherein the zigzag device comprises a seventh winding around the first core, comprising a first terminal coupled to the sixth AC connection terminal and a second terminal coupled to a neutral terminal for the neutral connection; an eighth winding around the second core, comprising a first terminal coupled to the second AC connection terminal, and a second terminal coupled to the neutral terminal; and a ninth winding around the third core, comprising a first terminal coupled to the fourth AC connection terminal, and a second terminal coupled to the neutral terminal.

[0071] Item 8. The transformer of any of Items 1-7, wherein the first, second and third cores comprise first, second, and third cores of a three-phase magnetic core structure.

[0072] Item 9. The transformer of any of Items 1-8, wherein the AC input voltage is about V3 times of the AC output voltage,

[0073] Item 10. The transformer of any of Items 1-9, wherein the delta-connected transforming device is further configured to transform the AC input voltage in a range of

330V- 390V to the AC output voltage in a first range of 190V-225V or in a second range of 570V-675V.

[0074] Item 11 . It is provided an electronic device comprising the transformer of any of Items 1-10.

[0075] Item 12. The electronic device of Item 11 , wherein the electronic device is an AC power supply device.

[0076] Item 13. The electronic device of Item 12, wherein the AC power supply device is UPS.

[0077] Item 14. The electronic device of Item 13 , wherein the UPS comprises an inverter comprising the transformer.

[0078] Item 15. It is provided a method for manufacturing a transformer. The method comprises providing a delta-connected transforming device comprising windings disposed around cores for phases of AC power and configured to transform AC input voltages to AC output voltages; and providing a zigzag device comprising windings disposed around the three cores and coupled to the delta-connected transforming device to form a neutral 5 connection for zero sequence currents of the transformer,

[0079] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be 10 advantageous. Likewise, while several specific implementation details are contained in the above discussions,, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. On the other hand, 15 various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination. [0080] Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A transformer (30) comprising: a delta-connected transforming device comprising windings disposed around cores for phases of alternative current (AC) power and configured to transform AC input voltages to AC output voltages; and a zigzag device comprising windings disposed around the cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer,

2, The transformer of Claim 1, wherein the delta-connected transforming device comprises a first transforming unit comprising: a first core of the cores; a first winding (LI 11) around the first core, comprising a first terminal coupled to a first AC connection terminal (Us) and a second terminal coupled to a second AC connection terminal (Up); and a second winding (LI 12) around the first core, comprising a first terminal coupled to the second AC connection terminal (Up) and a second terminal; a second transforming unit comprising: a second core of the cores; a third winding (L 121) around the second core, comprising a first terminal coupled to a third AC connection terminal (Vs) and a second terminal coupled to a fourth AC connection terminal (Vp) and the second terminal of the second winding (LI 12); and a fourth winding (LI 22) around the second core, comprising a first terminal coupled to the fourth AC connection terminal (Vp) and a second terminal; and a third transforming unit comprising: a third core of the cores; a fifth winding (L131) around the third core, comprising a first terminal coupled to a fifth AC connection terminal (Ws) and a second terminal coupled to a sixth AC connection terminal (Wp) and the second terminal of the fourth winding (Ll 22); and a sixth winding (LI 32) around the third core, comprising a first terminal coupled to the sixth AC connection terminal (Wp) and a second terminal coupled to the second AC connection terminal (Up),

3. The transformer of Claim 2, wherein the zigzag device comprises a first zigzag unit comprising: a seventh winding (LI 13) around the first core, comprising a first terminal and a second terminal coupled to a neutral terminal (N) for the neutral connection; and an eighth winding (LI 14) around the first core, comprising a first terminal and a second terminal coupled to the fourth AC connection terminal (Vp); a second zigzag unit comprising: a ninth winding (LI 23) around the second core, comprising a first terminal coupled to the first terminal of the eighth winding (LI 14) and a second terminal coupled to the neutral terminal (N); and a tenth winding (LI 24) around the second core, comprising a first terminal and a second terminal coupled to the sixth AC connection terminal (Wp); and a third zigzag unit comprising: an eleventh winding (LI 33) around the third core, comprising a first terminal coupled to the first terminal of the tenth winding (LI 24) and a second terminal coupled to the neutral terminal (N); and a twelfth winding (LI 34) around the third core, comprising a first terminal coupled to the first terminal of the seventh winding (LI 13) and a second terminal coupled to the second AC connection terminal (Up).

4, The transformer of Claim 1, wherein the delta-connected transforming device comprises a first transforming unit comprising: a first core of the cores; a first winding (L211) around the first core, comprising a first terminal coupled to a first AC connection terminal (Us) and a second terminal coupled to a second AC connection terminal (Up); a second winding (L212) around the first core, comprising a first terminal coupled to the second AC connection terminal (Up) and a second terminal; and a third winding (L213) around the first core, comprising a first terminal coupled to the second terminal of the second winding (L212) and a second terminal; a second transforming unit comprising: a second core of the cores; a fourth winding (L221) around the second core, comprising a first terminal coupled to a third AC connection terminal (Vs) and a second terminal coupled to a fourth AC connection terminal (Vp); a fifth winding (L222) around the second core, comprising a first terminal coupled to the fourth AC connection terminal (Vp) and a second terminal; and a sixth winding (L223) around the second core, comprising a first terminal coupled to the second terminal of the fifth winding (L222) and a second terminal coupled to the second AC connection terminal (Up); and a third transforming unit comprising: a third core of the cores; a seventh winding (L231) around the third core, comprising a first terminal coupled to a fifth AC connection terminal (Ws) and a second terminal coupled to a sixth AC connection terminal (Wp) and the second terminal of the third winding (L213); an eighth winding (L232) around the third core, comprising a first terminal coupled to the sixth AC connection terminal (Wp) and a second terminal; and a ninth winding (L233) around the third core, comprising a first terminal coupled to the second terminal of the eighth winding (L231 ) and a second terminal coupled to the fourth AC connection terminal (Vp),

5. The transformer of Claim 4, wherein the zigzag device comprises a tenth winding (L214) around the first core, comprising a first terminal coupled to the second terminal of the fifth winding (L222) and a second terminal coupled to a neutral terminal (N) for the neutral connection; an eleventh winding (L224) around the second core, comprising a first terminal coupled to the second terminal of the eighth winding (L232) and a second terminal coupled to the neutral terminal (N); and a twelfth winding (234) around the third core, comprising a first terminal coupled to the second terminal of the second winding (L212) and a second terminal coupled to the neutral terminal (N).

6. The transformer of Claim 1, wherein the delta-connected transforming device comprises a first transforming unit comprising; a first core of the cores; a first winding (L311) around the first core, comprising a first terminal coupled to a first AC connection terminal (Us) and a second terminal coupled to a second AC connection terminal (Up); and a second winding (LI 12) around the first core, comprising a first terminal coupled to the second AC connection terminal (Up) and a second terminal; a second transforming unit comprising; a second core of the cores; a third winding (L321) around the second core, comprising a first terminal coupled to a third AC connection terminal (Vs) and the second terminal of the first winding (L311 ), and a second terminal coupled to a fourth AC connection terminal (Vp); and a fourth winding (L322) around the second core, comprising a first terminal coupled to the fourth AC connection terminal (Vp) and the second terminal of the third winding (L32I), and a second terminal; and a third transforming unit comprising: a third core of the cores; a fifth winding (L331 ) around the third core, comprising a first terminal coupled to a fifth AC connection terminal (Ws) and the second terminal of the fourth winding (L322), and a second terminal coupled to the sixth AC connection terminal (Wp); a sixth winding (L332) around the third core, comprising a first terminal coupled to the sixth AC connection terminal (Wp) and the second terminal of the fifth winding (L331), and a second terminal coupled to the first AC connection terminal (Us) and the first terminal of the first winding (L311 ).

7, The transformer of Claim 6, wherein the zigzag device comprises a seventh winding (L313) around the first core, comprising a first terminal coupled to the sixth AC connection terminal (Wp) and a second terminal coupled to a neutral terminal (N) for the neutral connection; an eighth winding (L323) around the second core, comprising a first terminal coupled to the second AC connection terminal (Up), and a second terminal coupled to the neutral terminal (N); and a ninth winding (234) around the third core, comprising a first terminal coupled to the fourth AC connection terminal (Vp), and a second terminal coupled to the neutral terminal (N).

8. The transformer of any of Claims 2-7, wherein the first, second and third cores comprise first, second, and third cores of a three-phase magnetic core structure,

9. The transformer of claim 6 or 7, wherein the AC input voltage is about V3 or times of the AC output voltage.

10. The transformer of claim 9, wherein the delta-connected transforming device is further configured to transform the AC input voltage in a range of 330V- 390V to the AC output voltage in a first range of 190V-225 V or in a second range of 570V-675V.

11. An electronic device comprising the transformer of any of Claims 1-10.

12. The electronic device of Claim 11 , wherein the electronic device is an AC power supply device.

13. The electronic device of Claim 12, wherein the AC power supply device is uninterrupted power supply (UPS).

14. The electronic device of Claim 13, wherein the UPS comprises an inverter comprising the transformer,

15. A method for manufacturing a transformer, comprising: providing a delta-connected transforming device comprising windings disposed around cores for phases of alternative current (AC) power and configured to transform AC input voltages to AC output voltages; and providing a zigzag device comprising windings disposed around the three cores and coupled to the delta-connected transforming device to form a neutral connection for zero sequence currents of the transformer.