CN202488359U - A Matrix AC-AC High Voltage Frequency Converter Topology - Google Patents

Abstract

The utility model discloses a matrix AC-AC (Alternate Current to Alternate Current) high voltage frequency converter topological structure. According to the topological structure, the AC-AC high voltage frequency conversion is directly carried out; the four-quadrant operation can be implemented; a nonconventional matrix structure is adopted; the number of power switching devices is greatly reduced; and the cost is reduced. Each input phase of a frequency converter is respectively connected to at least two output phase of the frequency converter by at least two power chains and each output phase is respectively connected to at least two input phases by at least two power chains, wherein each power chain is formed by connecting at least one inductance with at least one H-bridge power unit SM in series. The three-phase/three-phase high voltage frequency converter disclosed by the utility model only needs six power chains, the transformer can be not required, and the cost and the volume are greatly reduced; and the four-quadrant work is implemented and the matrix AC-AC high voltage frequency converter topological structure can be widely used in application places of high voltage motor drive, wind power generation, a renewable energy generation grid-connected interface, power system interconnection, low frequency power transmission, a FACTS (Flexible Alternate Current Transmission System) or DFACTS (Distribution Flexible Alternate Current Transmission System) device, a power electronic transformer and the like.

Description

A Matrix AC-AC High Voltage Frequency Converter Topology

technical field

The utility model relates to a matrix AC-AC high-voltage frequency converter topology structure with a non-traditional matrix structure.

Background technique

High-voltage frequency converter is a special electrical equipment that adopts power electronic conversion technology to steplessly adjust the speed of high-voltage motors to meet the requirements of speed control in the production process. It has the characteristics of high efficiency, good energy-saving effect and high power factor, and is widely used Used in various industrial applications.

Due to the relatively low withstand voltage of power electronic switching devices, the most commonly used topology for high-voltage inverters is the cascaded H-bridge multilevel converter topology. "High-power inverter" is the topology of cascaded H-bridge multilevel converters. High-voltage frequency converters also adopt a diode-clamped three-level converter topology, for example, the Chinese patent publication No. CN1996734 "based on diode-clamped three-level 6kV high-voltage frequency converter". High-voltage inverters also have high-voltage inverter topologies that use IGBTs in direct series connection. For example, the Chinese patent publication No. CN201054550 discloses "IGBT direct series high-voltage inverters" and the Chinese patent publication No. CN101826838A discloses "A High Energy Efficiency IGBT directly connected in series with multi-level high-voltage frequency conversion speed control device". However, all the above-mentioned high-voltage frequency converters require input transformers, and some even require zigzag transformers with complex structures and large volumes. The article "An innovative modular multilevel converter topology suitable for a wide power range" (authored by Lesnicar, A. and Marquardt, R.) published in the international conference Power Tech Conference Proceedings, 2003 IEEE Bologna and published in "Chinese Journal of Electrical Engineering" 2009 "New Multi-level VSC Sub-module Capacitance Parameters and Voltage Equalization Strategy" (author Ding Guanjun, etc.) published on pages 1-6 of Volume 29, Issue 30, 2010, and "A No-Voltage Four-quadrant High-Voltage Frequency Converter Topology of Transformer" proposed a modular cascaded multi-level converter topology using a half-bridge structure, which can achieve four-quadrant operation and does not require a transformer, but the DC side capacitor voltage of each sub-module The fluctuation is greatly affected by the AC frequency, the lower the frequency, the greater the fluctuation of the capacitor voltage, so the inverter is not suitable for starting and running from low frequency.

The high-voltage inverter topology mentioned above belongs to the AC-DC-AC inverter structure, that is, it first changes from AC to DC (called rectification), and then from DC to AC (called inverter). The Chinese Patent Publication No. CN102185490A "Medium Voltage Frequency Converter for AC-AC Direct Conversion" proposes an AC-AC direct conversion frequency converter topology, which can realize direct frequency conversion from AC to AC, but it requires step-up and step-down voltage transformer, increasing the size and cost. "A new family of matrix converters" published in the International Conference Industrial Electronics Society, 2001. IECON '01 (Erickson R. W. and Al-Naseem O. A.) and in "Control and Decision Making" (2004 p. The article "Modeling and Simulation of a Novel Multilevel Matrix Converter" published in Volume 19, Issue 10, pages 1159-1162 (author Zhang Huaqiang, etc.) proposed an H-bridge matrix multilevel conversion Device topology, as shown in Figure 1 and Figure 1a. In this topology, an H-bridge is used to replace the bidirectional switch in the traditional matrix converter, and an inductor is connected in series on each phase of the two AC sides, where SM represents the H-bridge power unit. However, this topology has the risk of direct short circuit of the DC side capacitors of each unit during control. For example, if the four unit branches in the upper left corner of the matrix are in the conduction state, as shown in Figure 2, these four units will form a closed loop, resulting in a short circuit between the DC side capacitors of the four units. In addition, this topology requires nine power chains composed of H-bridge power units in series, and the number of power switching devices is large.

Utility model content

The purpose of this utility model is to solve the above problems, to provide a matrix AC-AC high-voltage frequency converter topology, which directly performs AC-AC high-voltage frequency conversion, can realize four-quadrant operation, and adopts a non-traditional matrix structure. The number of power switching devices is reduced, and the cost is reduced.

In order to achieve the above object, the utility model adopts the following technical solutions:

A matrix AC-AC high-voltage inverter topology, each input phase of the inverter is connected to at least two output phases of the inverter through at least two power chains, and each output phase is connected to at least two power chains respectively connected to at least two input phases; wherein each power chain is composed of at least one inductor connected in series with at least one H-bridge power unit SM.

The power chain is composed of two inductors L connected in series with at least one H-bridge power unit SM, wherein the two inductors L are arranged symmetrically at the outer terminals of the H-bridge power unit SM at both ends.

The H-bridge power unit consists of four power electronic switches with anti-parallel diodes and capacitors.

The input end of the frequency converter is connected to a power supply directly or through a transformer, and the output end is connected to a motor or a transformer or another power supply.

The input/output phases of the frequency converter are three-phase/three-phase, three-phase/two-phase, two-phase/three-phase or two-phase/two-phase.

Compared with the prior art, the novelty and creativity of the utility model are embodied in:

1) The three-phase/three-phase high-voltage inverter only needs six power chains, which is one-third less than the nine power chains required by the existing matrix high-voltage inverter, greatly reducing the cost and volume;

2) Each power chain contains an inductor, which avoids the risk of direct short circuit of the DC side capacitor of the H-bridge power unit;

3) The high-voltage frequency converter does not need a transformer, which reduces the size and cost.

4) Perform AC-AC frequency conversion directly, without converting AC into DC, and then converting DC into AC, which improves efficiency.

The utility model relates to a matrix AC-AC high-voltage inverter topology structure, which has low cost and small volume, can realize four-quadrant work, and can be widely used in high-voltage motor drive, wind power generation, new energy power generation grid-connected interface, Applications such as grid interconnection, low-frequency power transmission, FACTS or DFACTS devices, and power electronic transformers.

Description of drawings

Fig. 1 is the topological structure of the existing matrix AC-AC high voltage frequency converter.

FIG. 1 a is a diagram of the H-bridge power unit of FIG. 1 .

Fig. 2 is the short circuit phenomenon of the existing matrix AC-AC high voltage inverter topology.

Fig. 3 is a topology structure of the three-phase/three-phase inverter of the present invention.

FIG. 3 a is a power chain topology of FIG. 3 .

Fig. 3b is another connection diagram of the three-phase/three-phase inverter topology shown in Fig. 3 of the present invention.

Fig. 3c is another connection diagram of the three-phase/three-phase inverter topology shown in Fig. 3 of the present invention.

Fig. 3d is another connection diagram of the three-phase/three-phase inverter topology shown in Fig. 3 of the present invention.

Fig. 3e is another connection diagram of the three-phase/three-phase inverter topology shown in Fig. 3 of the present invention.

Fig. 3f is another connection diagram of the three-phase/three-phase inverter topology shown in Fig. 3 of the present invention.

Fig. 4 is the topology structure of the three-phase/two-phase inverter of the present invention.

Fig. 5 is the topology structure of the two-phase/three-phase inverter of the present invention.

Fig. 6 is another topological structure of the power chain in the frequency converter of the present invention.

Fig. 7 is a three-phase/three-phase frequency converter of the present invention used for motor drive.

Fig. 8 is the frequency converter of the present invention used for direct drive wind power generation grid connection.

Fig. 9 is that the frequency converter of the present invention is used in the unified power flow controller.

Fig. 10 shows that the frequency converter of the present invention is used for grid interconnection.

Fig. 11 is an embodiment of the frequency converter of the present invention used in a power electronic transformer.

Fig. 12 is another embodiment of the frequency converter of the present invention used in power electronic transformers.

Among them, 1. H-bridge power unit SM, 2. Power chain, 3. Frequency converter topology.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

Figure 1 and Figure 1a show the topological structure of the H-bridge power unit SM, which consists of four power electronic switches (S1, S2, S3 and S4) with anti-parallel diodes and a capacitor C. S1 and S2, S3 and S4 are respectively connected in series first and then connected in parallel with capacitor C.

Example 1:

3-3f show a topology structure and a power chain topology structure of the three-phase/three-phase inverter of the present invention, including six power chains 2 . Among them, the power chain 2 is composed of an inductor L connected in series with N H-bridge power units SM1, and N≥1; the input terminal A phase is connected to the output terminal U and V phase through two power chains 2, and the input terminal B phase passes through The two power chains 2 are connected to the output terminals V and W respectively, and the input terminal C phase is connected to the output terminal W and the U phase through two power chains 2 respectively; or in other words, the output terminal U phase is connected to the The input terminals C and A are connected, the output terminal V is connected to the input terminals A and B through two power chains 2 , and the output W phase is connected to the input terminals B and C through two power chains 2 . The input and output meet: each input phase is respectively connected to two output phases through two power chains 2 , and each output phase is respectively connected to two input phases through two power chains 2 .

Fig. 3b-Fig. 3f have given the other five topological structures of the three-phase/three-phase frequency converter of the present invention, wherein all meet: each input phase is all connected to two output phases respectively through two power chains, each Both output phases are connected to two input phases via two power chains respectively.

Example 2:

Fig. 4 has provided a kind of topological structure of the three-phase/two-phase frequency converter of the present invention, wherein satisfies: each input phase all connects to two output phases respectively through two power chains 2, each output phase all passes through The three power chains 2 are respectively connected to the three input phases.

Example 3:

Fig. 5 has provided a kind of topological structure of the two-phase/three-phase frequency converter of the present invention, wherein satisfies: each input phase is all connected to three output phases respectively through three power chains 2, and each output phase is all connected to three output phases through two power chains 2 Each power chain 2 is connected to the two input phases respectively.

Example 4:

In this embodiment, the frequency converter can adopt the structural form of Embodiment 1-3, but the power chain is replaced by another topology of the power chain 2 in the frequency converter of the present invention shown in Figure 6, which consists of two inductors It is formed in series with N H-bridge power units SM1, and the two inductors are arranged symmetrically at the two external terminals respectively.

Example 5:

Figure 7 shows the implementation of the three-phase/three-phase frequency converter of the present invention for motor drive, wherein the input terminals A, B and C are connected to the power grid in parallel, and the output terminals U, V and W are connected to the motor to realize the four-quadrant high-voltage motor Variable frequency drive.

Embodiment 6:

Figure 8 shows the implementation scheme of the inverter of the present invention for direct drive wind power generation grid connection, in which the input terminals A, B and C are connected to the grid in parallel, and the output terminals U, V and W are connected to the generator to realize direct AC- Grid-connected wind power generation.

Embodiment 7:

Fig. 9 has provided the implementation scheme that the frequency converter of the present invention is used for unified power flow controller, and wherein input terminal A, B and C are connected to grid in parallel, and output terminal U, V and W are connected to series transformer and are connected in series to circuit, and to circuit Perform power flow control or dampen oscillations.

Embodiment 8:

Figure 10 shows the implementation scheme of the inverter of the present invention for "back-to-back" grid connection, in which the input terminals A, B and C are connected to the grid 1, and the output terminals U, V and W are connected to the grid 2, so as to realize the non-connection of the two grids. Synchronous grid connection.

Embodiment 9:

Fig. 11 shows an embodiment of the frequency converter of the present invention used in a power electronic transformer, including two three-phase/three-phase frequency converters and one three-phase medium/high frequency transformer. The input terminals A, B and C of the first inverter are connected to the grid 1, and the output terminals U, V and W are connected to the primary side of the three-phase medium/high frequency transformer; the input terminals A2, B2 of the second inverter and C2 are connected to another grid 2, and its output terminals U2, V2 and W2 are connected to the secondary side of the medium/high frequency transformer. The number of H-bridge power units in the power chain of two frequency converters depends on the voltage level of the grid to which they are connected.

Example 10:

Figure 12 shows an implementation of the inverter of the present invention used in power electronic transformers, including two three-phase/two-phase inverters and a single-phase medium/high frequency transformer. The input terminals A, B and C of the first inverter are connected to the grid 1, and the output terminals U and V are connected to the primary side of the single-phase medium/high frequency transformer; the input terminals A2, B2 and C2 of the second inverter Another grid 2 is connected, and its output terminals U2 and V2 are connected to the secondary side of the single-phase medium/high frequency transformer. The number of H-bridge power units in the power chain of two frequency converters depends on the voltage level of the grid to which they are connected.

Claims (5)

1. A matrix AC-AC high-voltage frequency converter topology, characterized in that each input phase of the frequency converter is connected to at least two output phases of the frequency converter through at least two power chains, and each output phase is It is respectively connected to at least two input phases through at least two power chains; wherein each power chain is composed of at least one inductor connected in series with at least one H-bridge power unit SM. 2. The matrix AC-AC high-voltage converter topology according to claim 1, wherein the power chain is formed by connecting two inductors L and at least one H-bridge power unit SM in series, wherein the two inductors L In a symmetrical manner, they are respectively arranged at the outer terminals of the H-bridge power unit SM at the two ends. 3. The matrix AC-AC high-voltage frequency converter topology according to claim 1 or 2, wherein the H-bridge power unit is composed of four power electronic switches and capacitors with anti-parallel diodes. 4. The topology structure of matrix AC-AC high voltage frequency converter according to claim 1, characterized in that the input end of the frequency converter is directly connected to a power supply or through a transformer, and the output end is connected to a motor or a transformer or another power supply. 5. The matrix AC-AC high-voltage frequency converter topology according to claim 1, wherein the input/output phases of the frequency converter are three-phase/three-phase, three-phase/two-phase, two-phase/three-phase phase or two-phase/two-phase.

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