JPH0690565A - Power converter - Google Patents

Abstract

PURPOSE:To make a power converter a large-capacity one having less higher harmonic waves by multiplying it, using a transformer of the order of the nth power of 2 (n>=2, integer). CONSTITUTION:Open winding sides of converters 10-13 are serially connected to each other through delta.open star connection three-phase transformers 20-23. Open winding sides of converters 14-17 are serially connected to each other through delta.open delta connection three-phase transformers 24-27. A group of converters 100 and a group of converters 200 are connected in series and the connected converter groups are connected to a load or a power system 3. The output of pulse generating circuits 710-717 is inputted as a gate pulse to the converters 10-17 through operation phase difference adding circuits 700-707. The location set values of the operation phase difference adding circuits 700-707 are 0 deg., phi1, phi2 phi1+phi2, 30 deg., 20 deg.+phi1, 30 deg.+phi2, and 30 deg.+phi1+phi2 respectively. By making the output voltages of the two groups of power converters 30 deg. out of phase, a fifth, seventh, 17th, 19th, 29th, 31th... component can be theoretically zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device using a large-capacity semiconductor power converter for general industries, electric power, vehicles, etc., and particularly to a power converter having a large capacity using a multiple transformer. It can be used in various fields.

[0002]

2. Description of the Related Art As a method for increasing the capacity of a semiconductor power converter, for example, IEE, Transaction on Magnetics, Vol. 26, No. 5 (1990)
2247 to 2249 (IEEE Trans Magnetics Vo)
L.26, No.5 (1990), pp2247-224
As discussed in 9), there is a method of multiplexing two converters using two transformers. Two
By operating the converters with a phase difference of 30 degrees, a large capacity and low harmonics are achieved.

The Institute of Electrical Engineers of Japan "Semiconductor power conversion circuit" 1
There is also a method of reducing harmonics using staggered winding transformers, as discussed on pages 00-101.

[0004]

However, according to the above method, a method for further reducing harmonics has not been studied yet.
Further, there is no mention of an effective method for increasing the number of converters to be multiplexed or how the operating phase of each converter can reduce harmonics. Moreover, when using a zigzag winding transformer, the structure of the transformer becomes complicated.

It is an object of the present invention to multiplex converters in the n-th power of 2 (n ≧ 2, integer) by using a transformer that does not use a special winding so that harmonics are reduced. To obtain a large capacity power converter.

[0006]

In order to achieve the above object, the output of the n-th power of 2 (n ≧ 2, an integer) of a three-phase power converter using a self-extinguishing element is converted into a three-phase transformer. In the power converters that are multiplexed by using the power converter group A on the 2 (n-1) th power, they are connected to the delta connection side of the delta open star connection three-phase transformer, respectively, and the other (n-1) -1) The power converter group B on the platform is connected to the delta connection side of the delta / open delta connection three-phase transformer respectively, and the open delta windings of the three-phase transformers of the group B are connected in series in the same phase. Delta connection, the open star windings of the three-phase transformers of the group A are connected in series in the same phase, and one end of each series connection winding of the star windings is connected in the delta connection of the group B. Each of them is connected to a connection point, and electric power is output from the other end of the series connection winding of the star winding, The power converters of the group A and the group B which are connected to the input side of the three-phase transformer of the group B include a power converter having a voltage phase control means for driving the output voltage of the fundamental wave with a phase difference of 30 degrees. To do. Further, the voltage phase is changed in each power converter of each group.

For example, when the number of converters is 8 (n = 3), the phase of 4 units in each group is changed to operate. In this case, four units in each group are A ₁ , A ₂ , A ₃ , A ₄ and B ₁ , B ₂ ,
Assuming that B ₃ and B ₄ , the operating phase difference between A ₁ and A _{2 and} between A ₃ and A _{4 for} group A is φ ₁ . Furthermore A
Set the operating phase difference between ₁ (A ₂ ) and A ₃ (A ₄ ) to φ ₂ . That is, when A ₁ is the reference (0 °), A ₂ is φ ₁ and A ₃ is φ
Operate ₂ and A ₄ at φ ₁ + φ ₂ . The same applies to group B. In this case, the values of φ ₁ and φ ₂ are the (12 × i ± 1) th harmonics (i =
180 ° / (12) so that 1, 2, 3, ...
× i ± 1) (i = 1, 2, 3, ...)

[0008]

The phase difference between the output voltages of the power converters of groups A and B is set to 3
By setting it to 0 degree, the 5th, 7th, 17th, 19th, 29th, 31st ...
The harmonic components of the series can be made zero. Furthermore φ ₁ , φ
By selecting the values of ₂ ,…, φ _n-1 as above, harmonics are added in opposite phase between the two converters, so these components can theoretically be made zero by multiplexing. . As described above, it is possible to increase the capacity of the device and reduce the harmonics by using the power converter of the power of 2 to the nth power.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration for multiplexing using eight converters. Eight converters 10 to 17 with a common DC power supply 4
Are connected in parallel. The converters 10 to 13 are connected in series on the open winding side by three-phase transformers 20 to 23 of delta open star connection. The converters 14 to 17 are connected in series on the open winding side by three-phase transformers 24 to 27 having a delta / open delta connection. The former converter group 100 and the latter converter group 200 are further connected in series and further connected to the load or the power system 3. Hereinafter, the transformer winding on the converter side is called a primary winding, and the winding on the load side or the power system side is called a secondary winding. The outputs of the pulse generation circuits 710 to 717 are input as gate pulses to the converters 10 to 17 via the operation phase difference adding circuits 700 to 707. Running phase difference adding circuit 70
The phase setting value of 0 to 707 is 0 °, φ ₁ , φ ₂ , φ ₁ + φ ₂ ,
30 °, 30 ° + φ ₁ , 30 ° + φ ₂ , 30 ° + φ ₁ + φ
_Set to ₂ . The operation phase difference adding circuits 700 to 707 can be easily realized by using a timer, and each may generate a time delay corresponding to the operation phase. Usually, a microcomputer is used to perform software processing, so that it can be easily realized without adding a special circuit. FIG. 2 shows the winding configuration of the transformers 20 to 27. All primary windings are delta connected to zero the third harmonic component. Secondary windings are connected in series as shown to obtain three-phase output terminals U, V, W. Winding group a1 to a8, b1 to b8, c1 to c8 and winding group A1
-A4, B1-B4, C1-C4 and winding group A5-A
8, B5-B8, C5-C8 turns ratio is 1: a: √3a
, Converters 10 and 14, 11 and 15, 12 and 16,
13 and 17 are operated with a phase difference of 30 degrees. In this way, the transformer secondary side line voltage v _UV of the 5th, 7th, 17th, 1st
9, 29, 31 ... The next component can theoretically be zero. As described above, the harmonic components included in the transformer secondary side line voltage v _UV can be limited to the (12 × i ± 1) th order component.

Generally, the transformer primary voltage v can be expressed as the sum of the harmonic components as follows.

[0011]

[Equation 1]

At this time, since the transformer secondary side line voltage v _UV includes only the (12 × i ± 1) th order harmonic component, it can be expressed as the following equation.

[0013]

[Equation 2]

In the equation (2), k ₁ and k _{12i ± 1} are voltage reduction coefficients of each order component, and are shown in the equation (3).

[0015]

[Equation 3]

As shown in FIG. 3, the operation phase difference adding circuit 7
The set values of 00 to 707 are all 0 degrees in the converter group 100,
In the converter group 200, if it is set to 30 degrees (φ ₁ = φ ₂ = 0 °), an output voltage that is four times as large as that of one converter in each group is obtained, and the capacity of the converter is increased. be able to. In this case, all the voltage reduction coefficients of the equation (3) are "1". Next, consider the case where four converters in each group are operated in different phases. As shown in FIG. 1, the converter 10 is used as a reference (0
°), the converter 11 is φ ₁ , the converter 12 is φ ₂ , and the converter 1 is
Run 3 at φ ₁ + φ ₂ . The same applies to the converter group 200. In this way, the converter 10 and the converter 11
, The operating phase difference between the converter 12 and the converter 13 is φ ₁ , and the operating phase difference between the converters 10 and 11 and the converters 12 and 13 is φ.
It becomes ₂ . If φ ₁ and φ ₂ are set to 180 ° / (12 × i ± 1), the 2nd inverter (12 × i ± 1)
1) Since the second harmonic voltage has an opposite phase and can be canceled by multiplexing, this component can theoretically be made zero. If φ ₁ and φ ₂ are set to different values, the two types of harmonic components can be made zero. Usually, in order to downsize the harmonic filter equipment, components of low order are removed. Therefore, φ ₂ should be set so that the 11th and 13th components should be zero.
= 180 ° / 11 and φ ₁ = 180 ° / 13. In this case, k ₁₁ = k ₁₃ = 0, and the 11th and 13th order components can be made zero. FIG. 4 shows the relationship between the selection method of φ ₁ and φ ₂ and the voltage reduction coefficient k _{12i ± 1} .

In the above embodiment, φ ₁ = 180 ° / 13,
Although φ ₂ = 180 ° / 11 (case 1 in FIG. 4) is set, φ ₁ and φ ₂ are selected from FIG. 4 so that i is different. For example, as shown in FIG. 5, φ ₁ = 180 ° / 25, φ ₂ = 1
If 80 ° / 13 (case 5), then k ₂₅ and k from FIG.
₁₃ can be made zero, and voltage reduction coefficient k of other orders
₁₁ and k ₂₃ can also be made small. Therefore, there is an effect that harmonic components can be reduced as a whole. This means that if i of 12 × i ± 1 is the same and the double sign is different, 180 ° / (12 × i +
1) and the value of 180 ° / (12 × i−1) are small, the operation phase difference of 180 ° / (12 × i + 1) causes
This is because if the 2 × i + 1) -order higher harmonic wave is made to have an opposite phase and is canceled, the other (12 × i−1) th-order harmonic wave also has a substantially opposite phase relationship.

In the above embodiment, the operation phase difference is set so that the harmonic component of a specific order is zero, but an embodiment in which the specific order is not zero will be described below. The harmonic reduction coefficient is a function of φ ₁ and φ ₂ , and as shown in (Equation 3), the COS
Can be expressed by the product of (nφ _1/2) and COS (nφ _2/2). Figure 6 shows the relationship between COS (nφ / 2) and φ. (A) is n = 11, (b) is n = 13, (c) is n = 23,
(D) shows the case where n = 25. Horizontal axis is the operation phase difference φ
, Two values can be selected. This value is φ ₁ ,
φ ₂ It can be seen that one φ can be set near the region 2 to reduce the 11th and 13th order components, and the other φ can be set near the region 1 to reduce the 23rd and 25th order components. FIG. 7 shows an enlargement in the vicinity of regions 1 and 2. (A) shows the values of | COS (23φ / 2) | and | COS (25φ / 2) |, and (b) shows | COS (11φ / 2) | and | COS (13φ /
2) Indicates the value of |. If we focus only on the 11th harmonic and set it to zero, set _one of φ ₁ and φ ₂ to 180 ° / 1.
1 (the right end of region 2) and the other at 0 ° | COS (11
φ / 2) | = 0 and | COS (13φ / 2) | = 0.28. Therefore, | k ₁₁ | = 0, | k ₁₃ | = 0.28, and the effect of reducing the 13th harmonic component is 28%. Conversely, if only _one of φ ₁ and φ ₂ is set to 180 ° / 13 (the left end of region 2) and the other is set to 0 ° in order to make only the 13th harmonic zero, then | COS (11φ / 2) | = 0.24, | COS
(13φ / 2) | = 0. Therefore, | k ₁₁ | = 0.24, |
Since k ₁₃ | = 0, the effect of reducing the 11th harmonic component is 24
%. The same can be said for region 1.
φ ₁ . If one of φ ₂ is 180 ° / 23 (the right end of region 1) and the other is 0 °, then | COS (23φ / 2) | = 0 and the 23rd harmonic can be made zero, but | k ₂₅ | = 0.1
4 and the effect of reducing the 25th harmonic is 14%.
Conversely, if one value is 180 ° / 25 (the left end of region 1) and the other is 0 °, then | COS (23φ / 2) | = 0.13, and the 25th harmonic can be made zero, but | k ₂₃ | = 0.13, and the effect of reducing the 23rd harmonic is 13%. In the above-described embodiment, the method of selecting the values at the left and right ends in each area was described. However, selecting values between the areas does not make both values zero, but the values of the two functions are Can be made small at the same time. For example, assuming that the intermediate value is 180 ° / 24 in the region 1, | COS (23φ / 2) | = | COS
(25φ / 2) | = 0.065, which is about 1/2 of the value at both ends. In region 2, assuming 180 ° / 12, | COS (11φ / 2) | = | COS (13φ / 2) |
= 0.13, which is about 1/2 of the value at both ends
Becomes Finally, the product of the values selected from the two regions becomes the harmonic reduction coefficient k _{12i ± 1} , so if the operating phase difference is set to 180 ° / 24 in region ₁ and 180 ° / 12 in region 2, , The 11th, 13th, 23rd, and 25th order components can be reduced as a whole. In this case, the harmonic reduction coefficient of each order is | k ₁₁ | ≈0.10, |
k ₁₃ | ≈0.09, | k ₂₃ | ≈0.07, | k ₂₅ | ≈0.07
And the components of any order can be reduced on average.

In the above embodiment, the value of each area is 180
Although a value of ° / (12 × i) is selected, almost the same effect can be obtained by selecting a value in the middle of each area. φ
₁ is between 180 ° / 25 and 180 ° / 23, φ ₂ is 1
A value may be selected between 80 ° / 13 and 180 ° / 11.

In the above embodiment, n = 3, that is, the number of converters is 8, but 16 (n = 4), 3
If the number increases to 2 (n = 5), selectable angle φ
The number of 3 is increased to 3 and 4, and the effect of reducing harmonics is further increased accordingly. In the case of 16 units, the selectable angles are φ ₁ , φ ₂ , and φ ₃ , and by combining these,
The operating phase of each converter is as shown in FIG.

Further, if pulse width (PWM) control is also used, the harmonic voltage V _{12i ± 1} itself generated by one converter in the equation (2) can be reduced, so that the harmonic can be further reduced. it can.

In the above embodiments, the configuration of the inverse converter side is multiplexed to reduce the harmonic voltage on the load side or the power system side, but the forward converter side has the same configuration as shown in FIG. It can also be applied to circuit configurations. A forward converter is connected to the power system 6 and is connected to the reverse converter via the capacitors 4 and 5 in the DC part. In the present embodiment, the harmonics on the side of the power system 6 can also be reduced, so that there is an effect that the harmonic interference to the devices connected to the same power system can be reduced.

[0023]

According to the present invention, the capacity of a power converter can be increased to a power of 2n times the capacity of a single unit by multiplexing with a transformer, and harmonic components contained in the output voltage can be achieved. It is possible to reduce the noise, and to that extent, it is possible to reduce the harmonic interference given to other devices. Also,
This also has the effect of reducing the installed capacity of the filter for removing the generated harmonics.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main circuit according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a transformer winding according to an embodiment of the present invention.

FIG. 3 is a diagram showing voltage waveforms for explaining the operation of the present invention.

FIG. 4 is a diagram showing a relationship between an operation phase difference and a voltage reduction coefficient.

FIG. 5 is a diagram showing voltage waveforms for explaining the operation of the present invention.

FIG. 6 is a diagram showing a relationship between an operation phase difference and a voltage reduction coefficient for each order.

FIG. 7 is an enlarged view showing a relationship between an operation phase difference and a voltage reduction coefficient for each order.

FIG. 8 is a main circuit configuration diagram showing another embodiment of the present invention.

FIG. 9 is a main circuit configuration diagram showing another embodiment of the present invention.

[Explanation of symbols]

3 ... Load or power system, φ ₁ , φ ₂ , φ ₃ , ..., φ _n-1
… Phase difference, k ₁ … fundamental wave reduction coefficient, k _{12i ± 1} … the (12
Xi ± 1) Reduction coefficient of the harmonic component of the order 700 to 707 ... Operation phase difference adding circuit, a ... Transformer turn ratio, 710 to 717
... pulse generator circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akiteru Ueda 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (7)

[Claims] 1. The output of the n-th power of 2 (n ≧ 2, integer) of a three-phase power converter using a self-extinguishing element is multiplexed using a three-phase transformer, and (n-1) of 2 is used. The power converter group A on the platform is connected to the Delta connection side of the Delta / Open star connection three-phase transformer, and the power converter group B on the other 2 (n-1) platform is connected to the Delta / Open Delta connection. The three-phase transformers are respectively connected to the delta connection side, and the open delta windings of the three-phase transformers of the group B are connected in series in the same phase to form a delta connection, and the three-phase transformers of the group A are opened. The star windings are connected in series in the same phase, one end of each of the series connection windings of the star winding is connected to each of the delta connection points of the group B, and the series connection windings of the star windings are connected. In a power converter that outputs power from the other end, the output voltage phase control means for the fundamental wave of each power converter is provided in each converter. A power conversion device characterized by being provided for each. 2. The voltage phase control means of the power converter according to claim 1, wherein the phase difference of the output voltage is made different in each of the power converters of group A, and the output voltage of each of the power converters of group B is changed. The phase difference is such that each phase difference of the group A is further provided with a phase difference of 30 degrees. 3. The voltage phase of any one of the power converters of each group is used as a reference, and the voltage phases of the remaining power converters are 180 ° / (12 × i ± 1). ) (I
= 1, 2, ..., N-1), and sets based on n-1 kinds of angles obtained. 4. The voltage phase of the remaining power converter according to claim 3, wherein the voltage phase is 180 ° / (12 × i ± 1) (i = 1, 2,
, N-1) is selected as only one of the double signs over each i. 5. The voltage phase of any one power converter of the power converters of each group is used as a reference, and the voltage phases of the remaining power converters are i (= 1, 2, …, N-1)
About 180 ° / (12 × i + 1) to 180 ° /
N−1 having a value selected from the middle of (12 × i−1)
Each of the n-th power 3 phase power converters of the n-th power of 2 is provided with a voltage phase control means which is set on the basis of the angle of the type and the angle of the (2 (n-1) th power-n) type which is a combination thereof. A power converter characterized by the above. 6. The voltage phase of any one of the power converters in each group is used as a reference, and the voltage phases of the remaining power converters are i (= 1, 2, …, N-1)
About 180 ° × {1 / (12 × i + 1) + 1 / (1
The phase of the voltage phase control means is set based on (n-1) kinds of angles of 2 × i-1) / 2 and (2 (n-1) th power-n) kinds of angles formed by combining these. A power conversion device characterized by: 7. The voltage phase of any one power converter of the power converters of each group is used as a reference, and the voltage phases of the remaining power converters are i (= 1, 2, …, N-1)
About 180 ° / (12 × i) of (n−1) types of angles and combinations thereof ((n−2 of 2
1) A power conversion device characterized in that the phase of the voltage phase control means is set based on the angle of the power-n) type.