UPS system capable of reducing input harmonic waves

Abstract

The utility model discloses a UPS system capable of reducing input harmonic waves, which comprises N UPS modules and a transformation module, N is not less than two, the transformation module comprises a plurality of transformer units, a primary side winding of each transformer unit is of a triangular connection structure and is used for being connected with a power supply, and a secondary side winding of each transformer unit is of a triangular connection structure. The secondary side windings of each transformer unit are connected with the input ends of the UPS module in a one-to-one correspondence manner; the plurality of transformer units are respectively a first input transformer, a second input transformer, X third input transformers and Y fourth input transformers, a secondary side winding of the first input transformer is of a triangular connection structure, and a secondary side winding of the second input transformer is of a star connection structure; a secondary side winding of the third input transformer is of a positive zigzag connection structure, a secondary side winding of the fourth input transformer is of a negative zigzag connection structure, the difference value of X and Y is not larger than 1, and the sum of X and Y is N-2. According to the design, harmonic waves can be restrained by controlling the connection structure of the secondary side windings of the transformer units.

Description

Technical Field

[0001] The utility model relates to the technical field of harmonic elimination, in particular to a UPS system capable of reducing input harmonics. Background Art

[0002] As the requirements for power quality in various industries continue to increase, the requirements for improving UPS input harmonics are also increasing. There are generally two commonly used technical means to improve UPS harmonics. One is to combine UPS with multiple filters, and the other is to combine UPS with active filters.

[0003] However, when combining a UPS with a multi-stage filter, the cost is higher due to the high requirements for filter capacitors. When combining a UPS with an active filter, the cost of the product is also higher due to the high price of the active filter. Secondly, since the active filter uses IGBT as a control component, circuit protection devices must be installed to avoid miscompensation problems caused by faults and malfunctions, which also increases costs.

[0004] Therefore, the two existing technical means for improving harmonics in UPS will lead to increased costs, which is not conducive to their promotion and use. Utility Model Content

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a UPS system capable of reducing input harmonics. Each UPS system is equipped with an input transformer at the front end. Harmonics are suppressed by controlling the connection structure on both sides of each input transformer, thereby reducing harmonics and costs.

[0006] According to an embodiment of the first aspect of the present invention, a UPS system capable of reducing input harmonics includes: N UPS modules, where N is not less than two; a transformer module including multiple transformer units, each having a primary winding of a delta connection structure and being connected to a power supply, and each having a secondary winding connected one-to-one to an input terminal of the UPS module; the multiple transformer units respectively comprising a first input transformer, a second input transformer, X third input transformers, and Y fourth input transformers, the secondary winding of the first input transformer having a delta connection structure, the secondary winding of the second input transformer having a star connection structure, the secondary winding of the third input transformer having a forward zigzag connection structure, and the secondary winding of the fourth input transformer having a reverse zigzag connection structure, wherein the difference between X and Y is not greater than 1, and the sum of X and Y is N-2.

[0007] A UPS system capable of reducing input harmonics according to an embodiment of the present invention has at least the following beneficial effects:

[0008] The utility model discloses a UPS system capable of reducing input harmonics, comprising N UPS modules and a transformer module, wherein N is not less than 2, the transformer module comprising a plurality of transformer units, the primary winding of each transformer unit having a delta connection structure and being used to be connected to a power supply, the secondary winding of each transformer unit being connected one-to-one to an input end of the UPS module, and the plurality of transformer units being divided into a first input transformer, a second input transformer, a third input transformer and a fourth input transformer according to the connection structure of the secondary sides, wherein the secondary side of the first input transformer has a delta connection structure and there is only one first input transformer, the secondary side of the second input transformer has a star connection structure and there is only one second input transformer, the number of the third input transformers is S and the secondary side of the third input transformer has a forward zigzag connection structure, and the number of the fourth input transformers is Y and the secondary side of the fourth input transformer has a reverse zigzag connection structure.

[0009] When N is 2, there are only the first input transformer and the second input transformer in the UPS system, and the phase difference of each voltage vector in the UPS system is 30°. Therefore, the harmonics of the UPS system are lower than the case where the input transformers of both UPS modules are the first input transformer.

[0010] When N is an odd number, the phase difference between S and Y in the UPS system is always 1, and the phase difference of the voltage vector of the UPS system includes the phase difference of the voltage vector of the UPS system at N+1 and the phase difference of the voltage vector of the UPS system at N-1.

[0011] When N is an even number greater than 2, S and Y in the UPS system are equal, the phase difference of each voltage vector in the UPS system is less than 30°, and the phase difference decreases as N increases. Therefore, when N is larger, the harmonics of the UPS system are lower.

[0012] Therefore, the present invention provides an input transformer at the front end of each UPS system, and suppresses harmonics by controlling the connection structure on both sides of each input transformer, without adding additional electronic devices, thereby reducing costs while reducing harmonics.

[0013] According to some embodiments of the present invention, the plurality of transformer units are all three-phase transformers.

[0014] According to some embodiments of the present invention, the secondary side winding of the third input transformer includes a winding 4r, a winding 44r, a winding 4t, a winding 44t, a winding 4s and a winding 44s, the head end of the winding 4t is respectively connected to the head end of the winding 4s and the head end of the winding 4r and the head end of the 4r serves as the output end 4N, the head end of the winding 44r serves as the output end 4T, the tail end of the winding 44r is connected to the tail end of the winding 4t, the head end of the winding 44t serves as the output end 4S, the tail end of the winding 44t is connected to the tail end of the winding 4s, the head end of the winding 44s serves as the output end 4R, and the tail end of the winding 44s is connected to the tail end of the winding 4r.

[0015] According to some embodiments of the present invention, the number of turns of the winding 4s, the number of turns of the winding 4r and the number of turns of the winding 4t are the same, and the number of turns of the winding 44s, the number of turns of the winding 44r and the number of turns of the winding 44t are the same.

[0016] According to some embodiments of the present invention, when X is greater than 1, the turns ratio between the winding 4s and the winding 44t in the secondary winding of each of the third input transformers is different, the turns ratio between the winding 4r and the winding 44s in the secondary winding of each of the third input transformers is different, and the turns ratio between the winding 4t and the winding 44r in the secondary winding of each of the third input transformers is different.

[0017] According to some embodiments of the present invention, the secondary side winding of the fourth input transformer includes a winding 2s, a winding 22s, a winding 2t, a winding 22t, a winding 2r and a winding 22r, the head end of the winding 2s is respectively connected to the head end of the winding 2t and the head end of the winding 2r and the head end of the winding 2r serves as the output end 2N, the head end of the winding 22s serves as the output end 2T, the tail end of the winding 22s is connected to the tail end of the winding 2t, the head end of the winding 22r serves as the output end 2S, the tail end of the winding 22r is connected to the tail end of the winding 2s, the head end of the winding 22t serves as the output end 2R, and the tail end of the winding 22t is connected to the tail end of the winding 2r.

[0018] According to some embodiments of the present invention, the number of turns of the winding 2s, the number of turns of the winding 2r and the number of turns of the winding 2t are the same, and the number of turns of the winding 22s, the number of turns of the winding 22r and the number of turns of the winding 22t are the same.

[0019] According to some embodiments of the present invention, when Y is greater than 1, the turns ratio between the winding 22s and the winding 2t in the secondary winding of each of the fourth input transformers is different, the turns ratio between the winding 22r and the winding 2s in the secondary winding of each of the fourth input transformers is different, and the turns ratio between the winding 22t and the winding 2r in the secondary winding of each of the fourth input transformers is different.

[0020] According to some embodiments of the present invention, the phase angles of the plurality of transformer units are different.

[0021] According to some embodiments of the present invention, the plurality of transformer units are isolation transformers.

[0022] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0024] Figure 1 This is a connection diagram of a first input transformer of one embodiment of a UPS system capable of reducing input harmonics according to the present invention;

[0025] Figure 2 This is a voltage vector diagram of a first input transformer of one embodiment of a UPS system capable of reducing input harmonics according to the present invention;

[0026] Figure 3 This is a connection diagram of a second input transformer of one embodiment of a UPS system capable of reducing input harmonics according to the present invention;

[0027] Figure 4 In one embodiment of a UPS system capable of reducing input harmonics according to the present invention, a voltage vector synthesis diagram is shown when the transformer module includes a first input transformer and a second input transformer;

[0028] Figure 5 This is a connection diagram of a third input transformer of one embodiment of a UPS system capable of reducing input harmonics according to the present invention;

[0029] Figure 6 In one embodiment of a UPS system capable of reducing input harmonics according to the present invention, a voltage vector synthesis diagram is shown when the transformer module includes a first input transformer, a second input transformer, and a third input transformer;

[0030] Figure 7 This is a connection diagram of a fourth input transformer of one embodiment of a UPS system capable of reducing input harmonics according to the present invention;

[0031] Figure 8 In one embodiment of a UPS system capable of reducing input harmonics according to the present invention, a voltage vector synthesis diagram is shown when the transformer module includes a first input transformer, a second input transformer, and a fourth input transformer;

[0032] Figure 9 This is a voltage vector synthesis diagram of one embodiment of a UPS system capable of reducing input harmonics of the present invention when the transformer module includes a first input transformer, a second input transformer, a third input transformer and a fourth input transformer.

[0033] Description of the drawings: first input transformer 100 ; second input transformer 200 ; third input transformer 300 ; fourth input transformer 400 . DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0035] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientations or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", and "outside", are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0036] In the description of this utility model, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0037] In the description of this utility model, it should be noted that, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0038] like Figure 1 As shown in FIG-9 , according to an embodiment of the first aspect of the present invention, a UPS system capable of reducing input harmonics includes N UPS modules and a transformer module, where N is not less than two. The transformer module includes multiple transformer units, each of which has a primary winding in a delta connection structure and is used to connect to a power supply. The secondary winding of each transformer unit is connected one-to-one to the input terminal of the UPS module. The multiple transformer units are a first input transformer 100, a second input transformer 200, X third input transformers 300, and Y fourth input transformers 400. The secondary winding of the first input transformer 100 is in a delta connection structure, the secondary winding of the second input transformer 200 is in a star connection structure, the secondary winding of the third input transformer 300 is in a forward zigzag connection structure, and the secondary winding of the fourth input transformer 400 is in a reverse zigzag connection structure. The difference between X and Y is not greater than 1, and the sum of X and Y is N-2.

[0039] like Figure 1 、 3 As shown in Figures 5 and 7, in some embodiments of the present design, the multiple transformer units are all three-phase transformers.

[0040] like Figure 1 、 2 As shown, the secondary winding of the first input transformer 100 includes a winding 1t, a winding 1r, and a winding 1s, wherein the number of turns of the winding 1t, the winding 1r, and the winding 1s are the same. The voltage vectors output by the first input transformer 100 are respectively vector IT, vector 1R, vector 1S, vector -IT, vector -1R, and vector -1S. When the UPS system has only the first input transformer 100, no matter how many first input transformers 100 there are, there are only 6 pulses with a phase difference of 60 degrees between each pulse. The total harmonics are approximately 33%, which does not decrease. On the contrary, when there are multiple first input transformers 100, the interference pollution will increase due to the increased capacity.

[0041] like Figure 3 、 4As shown, the secondary winding of the second input transformer 200 includes a winding 3t, a winding 3r, and a winding 3s, wherein the number of turns of the winding 3t, the winding 3r, and the winding 3s are the same. The voltage vectors output by the second input transformer 200 are respectively vector 3T, vector 3R, vector 3S, vector -3T, vector -3R, and vector -3S. When the UPS system includes the first input transformer 100 and the second input transformer 200, there are 12 pulses in total with a phase difference of 30 degrees between each pulse. The total harmonics are approximately 12%, which is much lower than the 33% when the UPS system only includes the first input transformer 100, and the harmonics are reduced.

[0042] like Figure 5 、 6 As shown, in some embodiments of the present design, the secondary winding of the third input transformer 300 includes a winding 4r, a winding 44r, a winding 4t, a winding 44t, a winding 4s and a winding 44s, the head end of the winding 4t is respectively connected to the head end of the winding 4s and the head end of the winding 4r and the head end of 4r serves as the output end 4N, the head end of the winding 44r serves as the output end 4T, the tail end of the winding 44r is connected to the tail end of the winding 4t, the head end of the winding 44t serves as the output end 4S, the tail end of the winding 44t is connected to the tail end of the winding 4s, the head end of the winding 44s serves as the output end 4R, and the tail end of the winding 44s is connected to the tail end of the winding 4r.

[0043] like Figure 5 As shown, in some embodiments of the present design, the number of turns of winding 4s, the number of turns of winding 4r, and the number of turns of winding 4t are the same, and the number of turns of winding 44s, the number of turns of winding 44r, and the number of turns of winding 44t are the same, so that the vectors 4s, 4r, and 4t generated by the third input transformer 300 are of the same size, and the vectors 44s, 44r, and 44t are of the same size.

[0044] The phase voltage 4a is the voltage of the winding 4r minus the voltage of the winding 44s, the phase voltage 4b ​​is the voltage of the winding 4s minus the voltage of the winding 44t, and the phase voltage 4c is the voltage of the winding 4t minus the voltage of the winding 44r.

[0045] When the UPS system includes three UPS modules and the plurality of transformer units include a first input transformer 100, a second input transformer 200, and a third input transformer 300, as shown in FIG. Figure 6As shown, the composite diagram of the voltage vectors correspondingly includes vector IT, vector 1R, vector 1S, vector -IT, vector -1R, vector -1S, vector 3T, vector 3R, vector 3S, vector -3T, vector -3R, vector -3S, vector 4T, vector 4R, vector 4S, vector -4T, vector -4R and vector -4S, where vector 4T is composed of vector -4a and vector 4c, vector 4S is composed of vector -4c and vector 4b, and vector 4R is composed of vector -4b and vector 4b, and vector -4R and vector 4R have the same magnitude and opposite direction, vector -4S and vector 4S have the same magnitude and opposite direction, and vector -4T and vector 4T have the same magnitude and opposite direction.

[0046] In order to reduce harmonics, vector 4R should be located between vector -1S and vector 3R to form a new pulse, and as Figure 5 As shown, vector 4r and vector 1R are in phase, and vector -44s and vector 1S are in opposite phase. Figure 6 As shown, the phase angle of vector 4r differs from that of vector 4a by 15 degrees, and since the line voltage 4R is obtained by subtracting voltage 4b ​​from voltage 4a, the phase angle of vector 4R leads the phase angle of vector 4a by 30 degrees and lags the phase angle of vector -1S by 15 degrees. Therefore, voltage 4a is the same as the voltage of winding 3r, thereby deriving the corresponding settings of winding 4r and winding 44s. Similarly, the positions of vector 4T, vector 4S, vector -4T, vector -4R and vector -4S in the voltage vector synthesis diagram and the corresponding settings of winding 44r, winding 4t, winding 44t and winding 4s can be obtained, thereby deriving the structure of the third input transformer 300, wherein the derivation process of the positions of vector 4T, vector 4S, vector -4T, vector -4R and vector -4S in the voltage vector synthesis diagram and the corresponding settings of winding 44r, winding 4t, winding 44t and winding 4s will not be described in detail here.

[0047] In some embodiments of the present design, when X is greater than 1, the turns ratio between the winding 4s and the winding 44t in the secondary winding of each third input transformer 300 is different, so that the phase angles of the voltage vector of the phase voltage 4b ​​formed by combining the voltage vector of the winding 4s and the voltage vector of the winding 44t in each third input transformer 300 are different; the turns ratio between the winding 4r and the winding 44s in the secondary winding of each third input transformer 300 is different, so that the phase angles of the voltage vector of the phase voltage 4a formed by combining the voltage vector of the winding 4r and the voltage vector of the winding 44s in each third input transformer 300 are different; the turns ratio between the winding 4t and the winding 44r in the secondary winding of each third input transformer 300 is different, so that the phase angles of the voltage vector of the phase voltage 4c formed by combining the voltage vector of the winding 4t and the voltage vector of the winding 44r in each third input transformer 300 are different, thereby increasing the number of pulses and reducing harmonics.

[0048] like Figure 7 、 8 As shown, in some embodiments of the present design, the secondary winding of the fourth input transformer 400 includes a winding 2s, a winding 22s, a winding 2t, a winding 22t, a winding 2r and a winding 22r, the head end of the winding 2s is respectively connected to the head end of the winding 2t and the head end of the winding 2r and the head end of the winding 2r serves as the output end 2N, the head end of the winding 22s serves as the output end 2T, the tail end of the winding 22s is connected to the tail end of the winding 2t, the head end of the winding 22r serves as the output end 2S, the tail end of the winding 22r is connected to the tail end of the winding 2s, the head end of the winding 22t serves as the output end 2R, and the tail end of the winding 22t is connected to the tail end of the winding 2r.

[0049] like Figure 7 As shown, in some embodiments of the present design, the number of turns of winding 2s, the number of turns of winding 2r, and the number of turns of winding 2t are the same, and the number of turns of winding 22s, the number of turns of winding 22r, and the number of turns of winding 22t are the same, so that the vectors 2s, 2r, and 2t generated by the fourth input transformer 400 are of the same size, and the vectors 22s, 22r, and 22t are of the same size.

[0050] The phase voltage 2a is the voltage of the winding 2r minus the voltage of the winding 22t, the phase voltage 2b is the voltage of the winding 2s minus the voltage of the winding 22r, and the phase voltage 2c is the voltage of the winding 2t minus the voltage of the winding 22s.

[0051] When the UPS system includes three UPS modules and the plurality of transformer units include a first input transformer 100, a second input transformer 200, and a fourth input transformer 400, as shown in FIG. Figure 8 As shown, the composite diagram of the voltage vectors includes vector IT, vector 1R, vector 1S, vector -IT, vector -1R, vector -1S, vector 3T, vector 3R, vector 3S, vector -3T, vector -3R, vector -3S, vector 2T, vector 2R, vector 2S, vector -2T, vector -2R and vector -2S, where vector 2T is composed of vector -2a and vector 2c, vector 2S is composed of vector -2c and vector 2b, vector 2R is composed of vector -2b and vector 2b, and vector -2R is the same size as vector 2R but in opposite directions, vector -2S is the same size as vector 2S but in opposite directions, and vector -2T is the same size as vector 2T but in opposite directions.

[0052] In order to reduce harmonics, vector 2R should be located between vector 1R and vector 3R to form a new pulse, and as Figure 7 As shown, vector 2r and vector 1R are in phase, and vector -22t and vector 1T are in opposite phase. Figure 8As shown, the phase angle of vector 2a lags the phase angle of vector 1R by 15 degrees, and since the line voltage 2R is obtained by subtracting the voltage 2b from the voltage 2a, the phase angle of vector 2R leads the phase angle of vector 2a by 30 degrees. It can be seen that the phase angle of vector 2R leads the phase angle of vector 1R by 15 degrees and lags the phase angle of vector 3R by 15 degrees. Therefore, the voltage 2a is the same as the voltage of winding 3r, which leads to the setting of winding 2r and winding -22t. Similarly, vector 2T, vector 2S, and vector -2T, vector -2R and vector -2S are located at the positions of the voltage vector synthesis diagram and the corresponding settings of winding 22r, winding 2t, winding 22s and winding 2s, thereby deriving the structure of the fourth input transformer 400, wherein the derivation process of the positions of vector 2T, vector 2S, vector -2T, vector -2R and vector -2S at the positions of the voltage vector synthesis diagram and the settings of winding 22r, winding 2t, winding 22s and winding 2s is not repeated here.

[0053] In some embodiments of the present design, when Y is greater than 1, the turns ratio between the winding 22s and the winding 2t in the secondary winding of each fourth input transformer 400 is different, so that the phase angles of the voltage vector of the phase voltage 2c formed by combining the voltage vector of the winding 22s and the voltage vector of the winding 2t in each fourth input transformer 400 are different; the turns ratio between the winding 22r and the winding 2s in the secondary winding of each fourth input transformer 400 is different, so that the phase angles of the voltage vector of the phase voltage 2b formed by combining the voltage vector of the winding 22r and the voltage vector of the winding 2s in each fourth input transformer 400 are different; the turns ratio between the winding 22t and the winding 2r in the secondary winding of each fourth input transformer 400 is different, so that the phase angles of the voltage vector of the phase voltage 2a formed by combining the voltage vector of the winding 22t and the voltage vector of the winding 2r in each fourth input transformer 400 are different, thereby increasing the number of pulses and reducing harmonics.

[0054] like Figure 9As shown, in some embodiments of the present design, when the UPS system includes four UPS modules, the plurality of transformer units include a first input transformer 100, a second input transformer 200, a third input transformer 300, and a fourth input transformer 400, and the composite diagram of the voltage vectors correspondingly includes vector IT, vector 1R, vector 1S, vector -IT, vector -1R, vector -1S, vector 2T, vector 2R, vector 2S, vector -2T, vector -2R, vector -2S, vector 3T, vector 3R, vector 3S, vector -3T, vector -3R, vector -3S, vector 4T, vector 4R, vector 4S, vector -4T, vector -4R and vector -4S, that is, at this time the UPS system has a total of 24 pulses, and the phase angle of each pulse differs by 15 degrees, and the total harmonics are reduced to 7%. Compared with the case where N is less than 4, that is, compared with the three cases where the UPS system only includes the first input transformer 100 and the second input transformer 200, the UPS system only includes the first input transformer 100 and the second input transformer 200, or the UPS system only includes the first input transformer 100, the second input transformer 200 and the fourth input transformer 400, the effect of reducing harmonics is better.

[0055] In some embodiments of the present design, if the multiple transformer units are all three-phase transformers, when N is a power of 2, the number of pulses in the UPS system is 6 multiplied by N, and the phase angle difference of each phase is 360 degrees divided by the number of pulses. Among them, when N is 8, there are 48 pulses in the UPS system, the phase angle difference of each phase is 7.5 degrees, and the total harmonics are approximately 5%.

[0056] In some embodiments of the present design, the phase angles of the transformer units are different. If there are multiple transformer units with the same phase angle in the transformer module, the number of pulses in the UPS system is less than the product of 6 and N, and the harmonic suppression effect is reduced.

[0057] In some embodiments of the present design, the plurality of transformer units are isolation transformers, which are used to isolate the input and output of the UPS module, thereby suppressing interference.

[0058] The utility model discloses a UPS system capable of reducing input harmonics, comprising N UPS modules and a transformer module, wherein N is not less than 2. The transformer module comprises a plurality of transformer units, wherein the primary winding of each transformer unit has a delta connection structure and is used to be connected to a power supply, and the secondary winding of each transformer unit is connected one-to-one to the input end of the UPS module. The plurality of transformer units are divided into a first input transformer 100, a second input transformer 200, a third input transformer 300, and a fourth input transformer 400 according to the connection structure of the secondary sides. The secondary side of the first input transformer 100 has a delta connection structure, and there is only one first input transformer 100. The secondary side of the second input transformer 200 has a star connection structure, and there is only one second input transformer 200. There are S third input transformers 300, and the secondary side of the third input transformer 300 has a forward zigzag connection structure. There are Y fourth input transformers 400, and the secondary side of the fourth input transformer 400 has a reverse zigzag connection structure.

[0059] When N is 2, there are only the first input transformer 100 and the second input transformer 200 in the UPS system, and the phase difference between the voltage vectors in the UPS system is 30°. Therefore, the harmonics of the UPS system are lower than the case where the input transformers of the two UPS modules are both the first input transformer 100.

[0060] When N is an odd number, the phase difference between S and Y in the UPS system is always 1, and the phase difference of the voltage vector of the UPS system includes the phase difference of the voltage vector of the UPS system at N+1 and the phase difference of the voltage vector of the UPS system at N-1.

[0061] When N is an even number greater than 2, S and Y in the UPS system are equal, the phase difference of each voltage vector in the UPS system is less than 30°, and the phase difference decreases as N increases. Therefore, when N is larger, the harmonics of the UPS system are lower.

[0062] Therefore, the present invention provides an input transformer at the front end of each UPS system, and suppresses harmonics by controlling the connection structure on both sides of each input transformer, without adding additional electronic devices, thereby reducing costs while reducing harmonics.

[0063] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A UPS system capable of reducing input harmonics, characterized in that: include: N UPS modules, where N is not less than two; A transformer module comprising a plurality of transformer units, wherein the primary winding of each transformer unit is a delta-connected structure and is used to connect to a power source, and the secondary winding of each transformer unit is connected one-to-one to the input terminal of the UPS module; The multiple transformer units are respectively a first input transformer, a second input transformer, X third input transformers, and Y fourth input transformers; the secondary winding of the first input transformer is a delta connection structure, the secondary winding of the second input transformer is a star connection structure, the secondary winding of the third input transformer is a forward zigzag connection structure, and the secondary winding of the fourth input transformer is a reverse zigzag connection structure; wherein the difference between X and Y is not greater than 1, and the sum of X and Y is N-2.

2. The UPS system capable of reducing input harmonics according to claim 1, characterized in that: The plurality of transformer units are all three-phase transformers.

3. The UPS system capable of reducing input harmonics according to claim 2, characterized in that: The secondary side winding of the third input transformer includes a winding 4r, a winding 44r, a winding 4t, a winding 44t, a winding 4s and a winding 44s. The head end of the winding 4t is respectively connected to the head end of the winding 4s and the head end of the winding 4r, and the head end of the 4r serves as the output end 4N, the head end of the winding 44r serves as the output end 4T, the tail end of the winding 44r is connected to the tail end of the winding 4t, the head end of the winding 44t serves as the output end 4S, the tail end of the winding 44t is connected to the tail end of the winding 4s, the head end of the winding 44s serves as the output end 4R, and the tail end of the winding 44s is connected to the tail end of the winding 4r.

4. The UPS system capable of reducing input harmonics according to claim 3, characterized in that: The number of turns of the winding 4s, the number of turns of the winding 4r, and the number of turns of the winding 4t are the same, and the number of turns of the winding 44s, the number of turns of the winding 44r, and the number of turns of the winding 44t are the same.

5. The UPS system capable of reducing input harmonics according to claim 3, characterized in that: When X is greater than 1, the turns ratio between the winding 4s and the winding 44t in the secondary windings of each of the third input transformers is different, the turns ratio between the winding 4r and the winding 44s in the secondary windings of each of the third input transformers is different, and the turns ratio between the winding 4t and the winding 44r in the secondary windings of each of the third input transformers is different.

6. The UPS system capable of reducing input harmonics according to claim 2, characterized in that: The secondary side winding of the fourth input transformer includes a winding 2s, a winding 22s, a winding 2t, a winding 22t, a winding 2r and a winding 22r. The head end of the winding 2s is respectively connected to the head end of the winding 2t and the head end of the winding 2r, and the head end of the winding 2r serves as the output end 2N. The head end of the winding 22s serves as the output end 2T. The tail end of the winding 22s is connected to the tail end of the winding 2t. The head end of the winding 22r serves as the output end 2S. The tail end of the winding 22r is connected to the tail end of the winding 2s. The head end of the winding 22t serves as the output end 2R, and the tail end of the winding 22t is connected to the tail end of the winding 2r.

7. The UPS system capable of reducing input harmonics according to claim 6, characterized in that: The number of turns of the winding 2s, the number of turns of the winding 2r, and the number of turns of the winding 2t are the same, and the number of turns of the winding 22s, the number of turns of the winding 22r, and the number of turns of the winding 22t are the same.

8. The UPS system capable of reducing input harmonics according to claim 7, characterized in that: When Y is greater than 1, the turns ratio between the winding 22s and the winding 2t in the secondary winding of each of the fourth input transformers is different, the turns ratio between the winding 22r and the winding 2s in the secondary winding of each of the fourth input transformers is different, and the turns ratio between the winding 22t and the winding 2r in the secondary winding of each of the fourth input transformers is different.

9. The UPS system capable of reducing input harmonics according to claim 1, characterized in that: The phase angles of the multiple transformer units are different.

10. The UPS system capable of reducing input harmonics according to claim 1, characterized in that: The plurality of transformer units are all isolation transformers.

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