JPS62291906A - 3-phase/2-phase conversion transformer - Google Patents

Abstract

PURPOSE:To eliminate a single phase transformer and reduce the size of transformer in case a receiving voltage is low by connecting in series a first phase and a third phase coils of an 3-phase/2-phase conversion transformer, using both ends thereof as the secondary terminals of A seat and using both ends of the 2-phase coil as the secondary terminals of B seat. CONSTITUTION:Primary windings 16U, 16V, 16W of a 3-phase/2phase conversion transformer of a modified Wood bridge connection are connected in triangle and the second phase V of the secondary winding is formed by means of two secondary windings of 17v1, 17v2 with N turns. Moreover, the first phase U and third phase W of the secondary winding are formed by two secondary windings 17u1, 17u2, 17w1, 17w2 with N/3<1/2> turns. The secondary terminals of A seat are defined as TA-NA1. Moreover the secondary windings v1, v2 are secondary terminals TB-NB1, NB2-FB of the B seat. Thereby, a single phase transformer as the voltage booster are no longer necessary and size of transformer receiving a low voltage can be reduced.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention is a three-phase two-phase transformer that is used as a heavy duty transformer, and in particular has an improved two-phase side. This relates to a conversion transformer.

(Prior art) A heavy duty transformer for supplying power to high-speed electric cars includes a three-phase to two-phase conversion transformer 1 and a step-up transformer 2, which are called a modified Woodbridge connection, as shown in Fig. 16. The one composed of is used. This three-phase two-phase conversion transformer 1
The primary winding is star-shaped, and it receives power at three-phase voltage E□.
The next winding is a double triangular connection in which V-phases are connected in parallel.

If the voltage between one set of output terminals ac of this secondary winding is E2, the voltage between the other set of output terminals b'd' is E8/
-/d, and the phase difference between the voltages between the terminals ac and between the terminals b' and d' is 90 degrees.

The step-up transformer 2 has a voltage Ex/
This is an autotransformer that boosts J"l and generates voltage E2 between output terminals bd.

In this modified Woodbridge connected transformer system, the primary neutral point O can be directly grounded, so power can be received directly from the ultra-high voltage line, and the insulation of the primary winding can be significantly reduced.

However, power is not only received from an ultra-high voltage line, but also when the received voltage is 154 KV or less, and in this case, it is not necessarily necessary to draw out the neutral point on the primary side and ground it.

In addition to the three-phase to two-phase conversion transformer 1, there is also a step-up transformer 2.
This requires a large size, high manufacturing cost, a large installation space, and a large amount of construction cost.

Next, the reduction of the insulation class on the secondary side will be explained.

Figure 17 shows a power source 4 connected to the primary side of a single-phase two-winding heavy duty transformer 3, which is equivalent to the valve seat of a modified hood-bridge connected transformer.
is connected to the autotransformer 6A via the breaker 5 on the secondary side.
, 6B, and 6C, and an autotransformer 6A.

The neutral point of 68 and 6G is connected to the rail 7 and grounded via the discharger 8 to supply power to the electric car 9, indicating a conventional autotransformer power system (AT system).

In this system, the secondary side of the heavy duty transformer 3 is non-grounded, so the autotransformers 6A, 6B, and 6C are not connected, that is, they are cut off! Considering that a ground fault occurs on the secondary side when 5 is open, the electric car voltage ET
The insulation class corresponds to the secondary voltage E2, which is twice the voltage E2.

(Problems to be Solved by the Invention) Fig. 18 shows a recently developed new AT system in which the heavy duty transformer 10 has a voltage E2/2 equal to the electric vehicle voltage ET. The autotransformer 6A, which is a single-phase three-winding transformer having a set of secondary windings and is a substation AT (referred to as the first AT), is omitted.

That is, the power source 4 of voltage E is connected to the primary winding 11, and the secondary winding 1&! 12T, 12F neutral point side terminal N
A series capacitor 13 is connected in series to N2, a protective gap 14 is connected in parallel to the series capacitor 13, and the connection point N is connected to the rail 7 and grounded via the discharger 8, and the line side terminal T, It is a circuit configuration diagram in which autotransformers 6B and 6C are connected to F via a breaker 5 to supply power to an electric vehicle 9. Series capacitor 13 and protective gap 14
Although not necessarily a necessary device, the purpose of installing the series capacitor 13 is to compensate for the leakage reactance of the transformer winding, reduce voltage fluctuations on the secondary side, and improve the operating characteristics of the electric vehicle 9. When an overcurrent such as a short-circuit current starts to flow to the secondary winding 127.12F, the same current flows to the series capacitor 13, and the voltage e at both terminals rises and exceeds a certain value. Then, the gap discharges and shorts the series capacitor 13. When the series capacitor 13 is shorted by the protective gap 14, the magnitude of the overcurrent is limited to a value determined by the impedance of the power supply and the transformer. This is to ensure that there is no problem with short-circuit strength.In actual use, these circuits are prepared for both circuits, and the phase difference between their output voltages is 90 degrees, so that the load on each circuit is the same. In this case, the current from the three-phase power source on the primary side is designed to achieve three-phase balance.

In this new AT system, even when the breaker 5 is open, the connection point N is connected to the rail 7 and grounded via the discharger 8, so the insulation class on the secondary side is the electric car voltage E. In other words, a value corresponding to one voltage E2/2 of the secondary winding is sufficient, and can be half of that of the conventional system.

Moreover, since the secondary winding is connected at the connection point N and has the function of the autotransformer 6A of the first AT, the autotransformer 6A is unnecessary as shown in Fig. 18. can do.

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to provide a three-phase to two-phase conversion transformer that is compact and can be manufactured at a reduced manufacturing cost when applied to a case where the receiving voltage is 154 KV or less.

[Structure of the Invention] (Means for Solving the Problems) The heavy-duty transformer according to the present invention has a primary winding having a normal triangular connection, and a secondary winding in which the second phase has a number of turns N. It consists of two sets of coils, and two sets of coils in which the first and third phases each have a number of turns N/, /"J, and are connected in a square shape so that the phase difference is 120 degrees, Both ends of the latter's A-shaped connection are the secondary terminals of the A-seat, and both ends of the former second-phase coil are the B-seat's secondary terminals.6 (Function) When a single-phase load is connected to the next terminal, current flows through the primary and secondary windings of the 1st and 3rd phases, and when a single-phase load is connected to the secondary terminal of the B position of the 2nd phase coil,
A current having a phase difference of 90 degrees from the A point flows through the second phase primary winding and secondary winding.

When a load with the same impedance value is connected to the A and B secondary windings, a balanced three-phase current with the same magnitude and 120 degree phase difference will flow from the primary power supply. become.

(Embodiment) The present invention will be described below with reference to an embodiment shown in FIG. 1. The three-phase to two-phase conversion transformer 15 of this embodiment is U.

The primary windings 160, 16V, and 16M of the V and W phases are normally triangularly connected, and a secondary winding group is a special connection described later, and these winding groups are connected to one or more iron cores ( (not shown).

The secondary windings are two windings each (17u, , 17u
, , 17w, .

(1711, Coil 17u□ and 17
Connect w1, 17u, and 17w2 in the shape of A
Secondary terminal TA-NA□ of seat.

Assuming NA2-FA, the winding with the number of turns N is 17v, , 17
v2 to the secondary terminal of B position TB-Net +NBz-FB
shall be.

The shape of the A-shaped connection is the two windings 17u1 and 17i+□
Since the phase difference between 17u2 and 17w2 is 120 degrees, the voltage generated between the two major terminals T^-NA terminal-NA2-FA has a value corresponding to the number of turns N, It is equal to each voltage generated between NBt and between N8z and FB.

Therefore, the voltages generated on the secondary side have the same magnitude, and the phase difference between them is orthogonal at the A and B locations.

An example of the winding arrangement configuration of this transformer 15 is shown in FIG.

That is, on the iron core leg 18, the first group of secondary windings 17u1,1
7v1, 17w1, and the primary winding 160 on the outside.
．． 16V, 1611, and two groups of secondary windings 17u, 17v, 17su2 are wound on the outermost side, which is called a sand inch arrangement, and the structure of the first and third phases is as follows. Although they are exactly the same, the second phase has a different configuration from the other phases.

Next, if the configuration is as in this embodiment, A on the secondary side.

It will be explained that when a single-phase load is balanced on both B seats, a three-phase balanced load is applied to the primary side three-phase power supply.

First, in order to simplify the analysis of the current flowing through each part, the number of turns of each winding is determined by the ratio shown in Figure 3, that is, the winding 1
60, 16V, 16M to 1, windings 17u1, 17u2
゜On the secondary side, terminals TA are connected in series to both A and B.
-FA and TB-FB each correspond to 1.

In Figures 4 to 6, a three-phase power supply 19 is connected to the primary side, and A
This is the current distribution when the load 20 is taken only at the base, and the current flowing through the load 20 is assumed to be 1.

In FIG. 4, there is a load 20 between secondary terminals TA and NAi.

The flow rate of the secondary load current of 1 in the secondary winding 1t 17 w t is determined from the condition that the ampere turns of each phase are the same in the first and third phases. In Fig. 5, the secondary terminal When there is a load of 20 between NA2 and FA, the relationship is similar to that shown in Figure 4, but what is important here is that Figures 4 and 5
Under the conditions shown in the figure, the transformer must be designed so that its leakage impedance is approximately equal.

Figure 6 shows a case where both the conditions in Figures 4 and 5 are superimposed, and since the currents in the primary windings 160 and 161 are in phase, the current line in the primary winding 16U is calculated by the sum of the currents. 17u□,
Secondary current I flowing through 17w□ and 17u, , 17v
zA is naturally 1.

Figures 7 to 9 show the current distribution when a load 20 is applied only to the B position, but since the voltage generated at the B position is delayed by 90 degrees in phase with respect to the voltage generated at the A position, the current flowing Also 90
There is a phase difference of degrees, -j is added, and the subscript of each code/symbol is shown with B added instead of A. In Fig. 7, there is a load 20 between the secondary terminals TB and NBt, and the secondary winding 1
7V, and the secondary side load current -j1 flows through the load 20, and the primary current of -jl flows through the primary winding 16V, but this relationship is It is found under the condition that .

In Fig. 8, there is a load 20 between the secondary terminals NB2 and FB, and the relationship is the same as in Fig. 7, but what is important here is the conditions in Figs. 7 and 8. The goal is to make the leakage impedance almost equal.

Figure 9 shows a case where both the conditions in Figures 7 and 8 are superimposed, and since each current of the primary winding and the power supply are in phase, it can be found by the calculated sum, and the current IVB of the primary winding 16V Power supply V phase, W
The phase current IV11+IIB becomes -j1. The secondary side load current 12B is naturally -j1.

Figure 10 shows the current distribution in each part of the circuit, which is equivalent to when the same load 20 is connected to the A and B locations simultaneously and is applied to the new AT method, and the positive direction of each current is indicated by the arrow. It is displayed as . This figure 10 shows the case where both the conditions of figure 6 and figure 9 are superimposed, so the power supply current is ↑. +IVw↑
V has a phase difference of 90 degrees between each current in FIG. 6 and FIG. 9, and is determined by vector sum, and the vector diagram is as shown in FIG. 11.

In other words, the U-phase current iu of the power supply is ItlA+ItlB,
V phase current iv is -IVA+IVB, W phase current) y=-
Each is determined by IvA-Iva.

Therefore, as shown in Figures 10 and 11, if the same load is applied to the A and B locations on the secondary side, the electrical phase difference will be 1.
Since the angles are 20 degrees each, it can be seen that the three-phase currents are balanced.

Even if the secondary side has a special connection, since the primary side has a triangular connection, the third harmonic current included in the excitation current will circulate,
It works like a normal three phase transformer.

There are no inconveniences.

Next, the utilization factor of the winding will be explained. Since the voltage element can be known from FIG. 3 and the current element from FIG. 1O, the capacity of the winding can be determined by multiplying them. For the primary winding, the 1st phase (16U) and the 3rd phase (16V) are: I/Lz't'1.0 (= l 1 phase coil 17u1,1
7u.

The two-phase capacity of the third phase coils 17w□ and 17w2 is 1.
155 (= ±X2X4), 2nd phase coil 17V, 17
Since the capacity of V22J'J is 1.0 (= I It makes sense from a logical standpoint.

The capacity of the second phase coil is v3 times the capacity of each coil of the first or third phase, and the ratio is the same for the primary and secondary windings.

The total output of both seats on the secondary side is 2 (=-!-1x 4 x
), but the capacity input from the primary side is also 2 (=ν ton ×
11) and are consistent.

Therefore, if the winding capacity is 100% for the total secondary load 2, then both the primary winding and the secondary winding will be 107.7%, and their equivalent capacity will be 107.7%.

On the other hand, in the modified Woodbridge connection transformer shown in FIG. is 2
1.1% (= standing: "muri-) X 1 )," so the total equivalent capacity of both transformers is 121.1%.

Therefore, the transformer 15 of this embodiment requires 88.9% of the equivalent capacity. Furthermore, since there is no need to separately provide the e-step-up transformer 2, the etanta type is used, which allows the device to be smaller and lighter, and requires less space for installation.

Next, as a transformer for converting three-phase to two-phase, there is a conventional one using Scotto connection, an example of which is shown in FIG. 13, and will be explained by comparing it with the one of this embodiment.

In Fig. 13, the primary windings are the main seat coil 21M and the T seat coil 21T, and the secondary winding is the main seat coil 22M.
and a T-zashu coil 22T.

The secondary winding 22M for the main seat is divided into two parts and cross-connected to form a circulation circuit when the primary current for the T seat flows through the main seat fi21M.

Between terminals of secondary winding 22M and 22T (u-Ou, V-Ov
), the voltage between them is 1, the flowing current is 1, the primary winding is 1,
The voltage between the terminals of 121M and 21T (between U, V, and W) is 1
In each case, the terminals U-M of the primary winding 21M
During this period, the voltage between terminals M and W becomes 1/2, and the flowing current becomes 2/2.
√3, and the voltage between terminals V and M of the primary winding 21T is ν
At 1/2, the current flowing becomes 2/1, the voltage of the primary winding 922M of the main seat becomes 1, and the flowing current becomes 1/4'J.

Therefore, the Scotto connection transformer as shown in FIG. 13 is 1.
0 (= I X 1), so the total is 4.3
It becomes 1. The total output from the main seat on the secondary side and both seats on the T seat is 2.
0 (=IXIX2), so if this is taken as 100%, the equivalent capacity of this cost connection transformer is 107.7
% (=4.31/(2X2)), which is the same equivalent capacity as the transformer 15 of this embodiment.

The following two combinations of the core and windings of the Scotto connection transformer shown in FIG. 13 are employed. One method is to wind the main seat windings 21M and 22M and the T seat windings 21T and 22T on separate single-phase cores, but this method requires two cores with different dimensions. Since the cores are independent, it is difficult to stabilize each core during transportation, and a work space between each core and a space to provide insulation distance between the windings are required, which increases the size of the tank. There are some unlucky situations where the amount of oil increases or the weight/dimensions exceed the limit values, making it difficult to transport freight cars. Another method is to install windings 21M, 21T, 2
2M.

In the case of winding 22T, main winding 21M, 22
Since there is a 90 degree phase difference between the magnetic flux generated by M and the magnetic flux generated by the T coils 21T and 22T, the cross-sectional area of the yoke part and side leg part of the iron core 23 needs to be 1/v7 times that of the main leg part. be. Also, the winding capacity of main windings 21M and 22M is T winding 2.
The winding capacity of main seat windings 21M and 22M is 1.155 times the winding capacity of 1τ and 22 windings, and is designed so that the leakage impedance of the main seat and T seat is almost the same. Its outer diameter is larger than that of the state windings 21T and 22T. Therefore, the width dimension of the window on the side leg of the iron core 23 is tt1.
V, and there is a disadvantage that there are more types depending on the width dimension of the short rectangular core that constitutes the core than the general triple-walled core.

Point 1: In the transformer 15 of this embodiment, each winding is wound on the iron core 24, as shown in FIG.
vinegar,.

Since 16w and 17su2 have exactly the same configuration, they are symmetrical left and right with respect to the center line, and the width dimension V of the iron core window may be the same. Further, since the cross-sectional area of the yoke portion may be the same as the cross-sectional area of the leg portion, the structure of the connecting portion of the leg portion of the yoke portion is easy.

As described above, since the core according to this embodiment can be a normal three-phase iron core, the product price can be reduced.

It is clear that the insulation class of the secondary winding can be half that of the conventional one since its neutral point N is connected to the rail 7 and grounded via the discharger 8 during use. Similarly, circuit breakers, disconnectors, lightning arresters, and the like used in the secondary circuit may also be devices with low insulation class.

FIG. 12 shows a modification of the secondary winding, and A
The first phase coils 17u, l 17u and the third phase coils 17w, 17w2 of the counter are in the same shape, but their electrical characteristics are the same as in the present case, and their effects are also the same. .

As an example of the winding arrangement, a sand inch arrangement is shown in Fig. 2, but one group of secondary windings 17u, , 17v1°1
7v1 to the outside of the primary winding 160, 16V, 16M, 2
The group 17u2゜171/, , 1711+, is the primary winding 16
0,16V, may be placed inside the 1611 and one group of secondary windings 17u1.17v1.17w.

The two groups 17u, 17v, 17v2 may be separated and wound around separate core legs, or a split arrangement may be used in which both groups are arranged above and below and wound.

Which one to adopt is determined based on the manufacturing cost and the relationship between impedance voltage values, and the present invention does not particularly limit the winding arrangement.

〔Effect of the invention〕

As explained above, according to the present invention, the secondary winding is
Since one end can be grounded, it can be applied to new AT system circuits, and the insulation class on the secondary side can be halved.

In addition, because it does not require a special step-up transformer and can use a general-purpose triple core, it has a simple structure, can be made smaller and lighter, reduces manufacturing costs, and requires less space for installation. It is possible to provide a transformer for three-phase to two-phase conversion that is easy to use.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing one embodiment of a three-phase to two-phase conversion transformer according to the present invention, FIG. 2 is a schematic configuration diagram showing an example of the winding arrangement of the transformer shown in FIG. 1, and FIG. The figure is an explanatory diagram showing the turn ratio of each winding in the transformer shown in Fig. 1, and Figs. 4 to 6 are current distributions when the load is applied only to the A position in the transformer shown in Fig. 1. Explanatory diagrams showing, Figures 7 to 9
The figure is an explanatory diagram showing the current distribution when the load is applied only to the B position. Figure 10 is an explanatory diagram showing the current distribution and the positive direction of each current when the same load is applied to the A and B positions at the same time. 11
The figure is a vector diagram of the current in FIG. FIG. 12 is a wiring diagram showing a two-side winding according to another embodiment of the present invention, FIG. 13 is an explanatory diagram showing the wiring of a conventional Scott-connected transformer, the turns ratio and current flowing in each winding, and FIG. The figure is number 13
15 is a schematic diagram showing an example of the transformer shown in the figure, FIG. 15 is a schematic diagram showing an embodiment of the three-phase to two-phase conversion transformer according to the present invention, and FIG. 16 is a diagram of the conventional modified Woodbridge connection. Wiring diagram of a heavy duty transformer. Figure 17 shows AT in the conventional modified Woodbridge connection.
Figure 18 is a circuit diagram of the new AT system using a new three-phase to two-phase converter. 1... Three-phase to two-phase conversion transformer with modified Woodbridge connection 2... Step-up transformer 3.
10... Heavy duty transformer 4.19... Power supply 5... Breaker 6A, 6B, 5C... Auto transformer 7... Rail 8... Discharger 9... Electric car 13...Series capacitor 14...Protection gap 15...Three-phase two-phase conversion transformer 160.16V, 16V-primary winding 17u1, 17uit17v1, 17v2, 17w1,
17w2-Secondary winding 18... Core leg 20... Load 21M, 21T... Primary winding 2 of Scotto connection transformer
2M, 22T... 〃 〃 secondary winding 23
...Special core 24 for I...
・Mika Tetsushin agent for general three-phase Patent attorney Nori Ken Chika Yudo Hirofumi Mitsumata Fig. 7 Fig. 8 Fig. 9 Fig. 10 77 Gin Fig. 11 Fig. Nana B Fig. 12 Fig. 13 Fig. 15 Fig. 16

Claims (1)

[Claims] The primary winding is a triangular connection with the same number of turns for all three phases.
The secondary winding consists of two sets of coils in which the second phase has a number of turns of N, and two sets of coils each in which the first and third phases have a number of turns of N/√3. In a three-phase to two-phase conversion transformer having a coil group consisting of two sets of coils each connected in series so that the phase difference is 120 degrees, the first phase and the third phase are A transformer for three-phase to two-phase conversion, characterized in that both ends of the coils connected in series are used as secondary terminals at the A position, and both ends of the second phase coil are used as the secondary terminals at the B position.