阅读说明：本技术 一种九电平变换器 (Nine-level converter ) 是由 吴军科 熊攀 刘阳升 范兴明 于 2021-01-08 设计创作，主要内容包括：本发明公开了一种九电平变换器,包括串联电容组、串联双向开关组、开关电容单元和滤波电路；所述开关电容单元一侧分别与串联电容组中相邻电容的连接点连接,所述开关电容单元的另一侧与串联双向开关组中的相邻双向开关的连接点中的首末连接点分别连接；所述串联电容组的中间连接点与地连接；所述双向开关组的中间连接点与滤波电路连接；所述串联电容组的一端与串联双向开关组的一端连接；所述串联电容组的另一端与串联双向开关组的另一端连接。本发明提供的九电平变换器,通过开关电容单元可以产生九电平的输出电压,该电路结构所需的制作器件数量少,结构简单,可靠性高。(The invention discloses a nine-level converter, which comprises a series capacitor bank, a series bidirectional switch bank, a switch capacitor unit and a filter circuit, wherein the switch capacitor unit is connected with the filter circuit; one side of the switched capacitor unit is respectively connected with the connection points of adjacent capacitors in the series capacitor group, and the other side of the switched capacitor unit is respectively connected with the first and last connection points in the connection points of the adjacent bidirectional switches in the series bidirectional switch group; the middle connecting point of the series capacitor bank is connected with the ground; the middle connecting point of the bidirectional switch group is connected with the filter circuit; one end of the series capacitor bank is connected with one end of the series bidirectional switch bank; and the other end of the series capacitor bank is connected with the other end of the series bidirectional switch bank. The nine-level converter provided by the invention can generate nine-level output voltage through the switched capacitor unit, and the circuit structure has the advantages of less manufacturing device quantity, simple structure and high reliability.)

1. A nine-level converter, characterized by: the filter comprises a series capacitor bank, a series bidirectional switch bank, a switch capacitor unit and a filter circuit;

one side of the switched capacitor unit is respectively connected with the connection points of adjacent capacitors in the series capacitor group, and the other side of the switched capacitor unit is respectively connected with the first and last connection points in the connection points of the adjacent bidirectional switches in the series bidirectional switch group; the middle connecting point of the series capacitor bank is connected with the ground; the middle connecting point of the bidirectional switch group is connected with the filter circuit; one end of the series capacitor bank is connected with one end of the series bidirectional switch bank; and the other end of the series capacitor bank is connected with the other end of the series bidirectional switch bank.

2. The nine-level converter of claim 1, wherein: the filter circuit comprises an energy storage inductor and a filter capacitor, one end of the energy storage inductor is connected with the middle connection point of the bidirectional switch group, the other end of the energy storage inductor is connected with the filter capacitor, and the other end of the filter capacitor is connected with the ground.

3. The nine-level converter of claim 1, wherein: the series capacitor bank comprises a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4;

one end of the first capacitor C1 is connected to one end of the series switch group, the other end of the first capacitor C1 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the third capacitor C3, the other end of the third capacitor C3 is connected to one end of the fourth capacitor C4, and the other end of the fourth capacitor C4 is connected to the other end of the series switch group.

4. The nine-level converter of claim 1, wherein: the series bidirectional switch group comprises a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4;

one end of the first switch tube S1 is connected to one end of the series capacitor bank, the other end of the first switch tube S1 is connected to one end of the second switch tube S2, the other end of the second switch tube S2 is connected to one end of the third switch tube S3, the other end of the third switch tube S3 is connected to one end of the fourth switch tube S4, and the other end of the fourth switch tube S4 is connected to the other end of the series capacitor bank.

5. The nine-level converter of claim 1, wherein: one end of the energy storage inductor is connected with a connection point of the second switching tube S2 and the third switching tube S3, the other end of the energy storage inductor is connected with the filter capacitor, and the other end of the filter capacitor is connected with the ground.

6. The nine-level converter of claim 1, wherein: the switched capacitor unit comprises a middle positive level control module, a middle negative level control module and a switched capacitor module;

one end of the middle positive level control module is connected with a connection point between a first capacitor C1 and a second capacitor C2; the other end is connected with the connection point between the first switch tube S1 and the second switch tube S2;

one end of the middle negative level control module is connected with a connection point between a first capacitor C3 and a second capacitor C4; the other end is connected with the connection point between the first switch tube S3 and the second switch tube S4;

one end of the switched capacitor module is connected with a connection point between a first capacitor C2 and a second capacitor C3; the other end is connected with the connection point between the first switch tube S2 and the second switch tube S3.

7. The nine-level converter of claim 1, wherein: the middle positive level control module comprises a seventh switching tube and a diode; the collector of the seventh switching tube is connected with a connection point between a first capacitor C1 and a second capacitor C2; the emitter of the seventh switch tube is connected with the anode of a diode, and the cathode of the diode is connected with the connection point between the first switch tube S1 and the second switch tube S2.

8. The nine-level converter of claim 1, wherein: the middle negative level control module comprises an eighth switching tube and a diode; the cathode of the diode is connected with the connection point between the third capacitor C3 and the fourth capacitor C4; the anode of the diode is connected with the emitter of an eighth switching tube, and the collector of the eighth switching tube is connected with the connection point between the third switching tube S3 and the fourth switching tube S4.

9. The nine-level converter of claim 1, wherein: the switched capacitor module comprises a fifth switching tube S5, a sixth switching tube S6 and a flying capacitor C5;

an emitter of the fifth switching tube S5 is connected with the anode of the diode in series and then is connected with a connection point between the second capacitor C2 and the third capacitor C3 through the cathode of the diode; the collector of the fifth switching tube S5 is connected to the connection point between the first switching tube S1 and the second switching tube S2;

the collector of the sixth switching tube S6 is connected in series with the anode of the diode, and then connected to the connection point between the second capacitor C2 and the third capacitor C3 through the cathode of the diode; the collector of the sixth switching tube S6 is connected to the connection point between the third switching tube S3 and the fourth switching tube S4; one end of the flying capacitor C5 is connected to the collector of the fifth switching tube S5, and the other end is connected to the emitter of the sixth switching tube S6.

10. The nine-level converter of claim 1, wherein: the middle positive level control module comprises a seventh bidirectional switch and an eighth bidirectional switch which are connected in series; one end of the seventh bidirectional switch is connected with a connection point between the first capacitor C1 and the second capacitor C2; the other end of the first bidirectional switch is connected with one end of a second bidirectional switch, and the other end of the second bidirectional switch is connected with a connection point between the first switch tube S1 and the second switch tube S2;

the middle negative level control module comprises a ninth bidirectional switch and a tenth bidirectional switch which are connected in series; one end of the ninth bidirectional switch is connected with a connection point between a third capacitor C3 and a fourth capacitor C4; the other end of the second bidirectional switch is connected with one end of a third bidirectional switch, and the other end of the third bidirectional switch is connected with a connection point between the third switch tube S3 and the fourth switch tube S4.

Technical Field

The invention relates to the technical field related to power electronic conversion, in particular to a nine-level converter.

Background

The multilevel converter technology is a technology for realizing capacity expansion by changing the topological structure of a converter. Compared with a two-level converter and a three-level converter, the multi-level converter can reduce output harmonic waves at an alternating current side, reduce voltage stress of a switching tube, reduce the volume of a passive filter and provide an effective solution for electric energy conversion in high-power occasions such as high voltage/large current and the like.

The traditional multilevel topological converter is divided into a flying capacitor converter, a midpoint clamping converter, a cascaded H-bridge converter and the like according to the topological structure of a main circuit, wherein the flying capacitor converter has a large number of capacitors, and the capacitor voltage is difficult to control; the traditional neutral point clamped converter has more switches; cascaded H-bridge converters require multiple independent dc power supplies, resulting in higher system cost.

Disclosure of Invention

Therefore, the invention uses the topological characteristics of two multilevel converters of neutral point clamping and flying capacitor for reference, and aims to provide a nine-level converter which realizes nine-level mode conversion through different combination modes of switch capacitor units.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides a nine-level converter, which comprises a series capacitor bank, a series bidirectional switch bank, a switch capacitor unit and a filter circuit, wherein the switch capacitor unit is connected with the filter circuit;

one side of the switched capacitor unit is respectively connected with the connection points of adjacent capacitors in the series capacitor group, and the other side of the switched capacitor unit is respectively connected with the first and last connection points in the connection points of the adjacent bidirectional switches in the series bidirectional switch group; the middle connecting point of the series capacitor bank is connected with the ground; the middle connecting point of the bidirectional switch group is connected with the filter circuit; one end of the series capacitor bank is connected with one end of the series bidirectional switch bank; and the other end of the series capacitor bank is connected with the other end of the series bidirectional switch bank.

Furthermore, the filter circuit comprises an energy storage inductor and a filter capacitor, one end of the energy storage inductor is connected with the middle connection point of the bidirectional switch group, the other end of the energy storage inductor is connected with the filter capacitor, and the other end of the filter capacitor is connected with the ground.

Further, the series capacitor bank comprises a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4;

one end of the first capacitor C1 is connected to one end of the series switch group, the other end of the first capacitor C1 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the third capacitor C3, the other end of the third capacitor C3 is connected to one end of the fourth capacitor C4, and the other end of the fourth capacitor C4 is connected to the other end of the series switch group;

further, the series bidirectional switch group comprises a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4;

one end of the first switch tube S1 is connected to one end of the series capacitor bank, the other end of the first switch tube S1 is connected to one end of the second switch tube S2, the other end of the second switch tube S2 is connected to one end of the third switch tube S3, the other end of the third switch tube S3 is connected to one end of the fourth switch tube S4, and the other end of the fourth switch tube S4 is connected to the other end of the series capacitor bank;

furthermore, one end of the energy storage inductor is connected with a connection point of the second switching tube S2 and the third switching tube S3, the other end of the energy storage inductor is connected with the filter capacitor, and the other end of the filter capacitor is connected with the ground.

Further, the switched capacitor unit comprises a middle positive level control module, a middle negative level control module and a switched capacitor module;

one end of the middle positive level control module is connected with a connection point between a first capacitor C1 and a second capacitor C2; the other end is connected with the connection point between the first switch tube S1 and the second switch tube S2;

one end of the middle negative level control module is connected with a connection point between a first capacitor C3 and a second capacitor C4; the other end is connected with the connection point between the first switch tube S3 and the second switch tube S4;

one end of the switched capacitor module is connected with a connection point between a first capacitor C2 and a second capacitor C3; the other end is connected with the connection point between the first switch tube S2 and the second switch tube S3;

further, the middle positive level control module comprises a seventh switch tube and a diode; the collector of the seventh switching tube is connected with a connection point between a first capacitor C1 and a second capacitor C2; the emitter of the seventh switching tube is connected with the anode of a diode, and the cathode of the diode is connected with the connection point between the first switching tube S1 and the second switching tube S2;

further, the intermediate negative level control module comprises an eighth switching tube and a diode; the cathode of the diode is connected with the connection point between the third capacitor C3 and the fourth capacitor C4; the anode of the diode is connected with the emitter of an eighth switching tube, and the collector of the eighth switching tube is connected with the connection point between the third switching tube S3 and the fourth switching tube S4;

further, the switched capacitor module comprises a fifth switching tube S5, a sixth switching tube S6 and a flying capacitor C5;

an emitter of the fifth switching tube S5 is connected with the anode of the diode in series and then is connected with a connection point between the second capacitor C2 and the third capacitor C3 through the cathode of the diode; the collector of the fifth switching tube S5 is connected to the connection point between the first switching tube S1 and the second switching tube S2;

the collector of the sixth switching tube S6 is connected in series with the anode of the diode, and then connected to the connection point between the second capacitor C2 and the third capacitor C3 through the cathode of the diode; the collector of the sixth switching tube S6 is connected to the connection point between the third switching tube S3 and the fourth switching tube S4;

one end of the flying capacitor C5 is connected to the collector of the fifth switching tube S5, and the other end is connected to the emitter of the sixth switching tube S6.

Further, the middle positive level control module comprises a seventh bidirectional switch and an eighth bidirectional switch connected in series; one end of the seventh bidirectional switch is connected with a connection point between the first capacitor C1 and the second capacitor C2; the other end of the first bidirectional switch is connected with one end of a second bidirectional switch, and the other end of the second bidirectional switch is connected with a connection point between the first switch tube S1 and the second switch tube S2;

the middle negative level control module comprises a ninth bidirectional switch and a tenth bidirectional switch which are connected in series; one end of the ninth bidirectional switch is connected with a connection point between a third capacitor C3 and a fourth capacitor C4; the other end of the second bidirectional switch is connected with one end of a third bidirectional switch, and the other end of the third bidirectional switch is connected with a connection point between the third switch tube S3 and the fourth switch tube S4.

The invention has the beneficial effects that:

the nine-level converter provided by the invention can generate nine-level output voltage under the condition of less switching elements and capacitors through the combination change of the switched capacitor units, the number of manufacturing devices required by the circuit structure is less, the cost of the converter is reduced, the structure of the converter is simplified, the reliability is high, and the performance of the converter is more stable.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:

FIG. 1 is a schematic diagram of a nine-level circuit topology.

Fig. 2 is a diagram of a nine-level converter.

Fig. 3 is a schematic diagram of the current path at an output level of 4E.

Fig. 4 is a schematic diagram of the current path when the output level is 3E.

Fig. 5 is a schematic diagram of the current path when the output level is 2E.

Fig. 6(a) is a schematic diagram of a current path when the output level is E.

Fig. 6(b) is a schematic diagram of a current path when the output level is E, 2.

Fig. 7(a) is a schematic diagram 1 of a current path when the output level is 0.

Fig. 7(b) is a schematic diagram of a current path when the output level is 0, 2.

FIG. 8(a) is a schematic diagram of the current path at an output level of-E.

FIG. 8(b) is a schematic diagram of the current path at an output level of-E.

FIG. 9 is a schematic diagram of the current path at an output level of-2E.

FIG. 10 is a schematic diagram of the current path at an output level of-3E.

FIG. 11 is a schematic diagram of the current path at an output level of-4E.

Fig. 12 is a nine-level converter in which current can flow in both directions.

In the figure, 1 denotes a series capacitor bank, 2 denotes a series bidirectional switch bank, 3 denotes a switched capacitor unit, and 4 denotes a filter circuit; 31 denotes an intermediate positive level control module, 32 denotes an intermediate negative level control module, and 33 denotes a switched capacitor module.

Detailed Description

The present invention is further described with reference to the following drawings and specific examples so that those skilled in the art can better understand the present invention and can practice the present invention, but the examples are not intended to limit the present invention.

Example 1

As shown in fig. 1, the nine-level converter provided in this embodiment at least includes a series capacitor bank and a series bidirectional switch bank disposed between positive and negative dc buses, a switched capacitor unit, and a filter circuit;

one side of the switched capacitor unit is respectively connected with the connection points of adjacent capacitors in the series capacitor group, and the other side of the switched capacitor unit is respectively connected with the first and last connection points in the connection points of the adjacent bidirectional switches in the series bidirectional switch group; the middle connecting point of the series capacitor bank is connected with the ground; the middle connecting point of the bidirectional switch group is connected with the filter circuit;

the filter circuit comprises an energy storage inductor and a filter capacitor, one end of the energy storage inductor is connected with the middle connection point of the bidirectional switch group, the other end of the energy storage inductor is connected with the filter capacitor, and the other end of the filter capacitor is connected with the ground;

the series capacitor bank comprises a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4;

one end of the first capacitor C1 is connected to a positive input terminal of a dc power supply V, the other end of the first capacitor C1 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the third capacitor C3, the other end of the third capacitor C3 is connected to one end of the fourth capacitor C4, and the other end of the fourth capacitor C4 is connected to a negative input terminal of the dc power supply;

the series bidirectional switch group comprises a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4;

one end of the first switching tube S1 is connected to the positive input end of the dc power supply, the other end of the first switching tube S1 is connected to one end of the second switching tube S2, the other end of the second switching tube S2 is connected to one end of the third switching tube S3, the other end of the third switching tube S3 is connected to one end of the fourth switching tube S4, and the other end of the fourth switching tube S4 is connected to the negative input end of the dc power supply;

one end of the energy storage inductor is connected with a connection point of the second switching tube S2 and the third switching tube S3, the other end of the energy storage inductor is connected with the filter capacitor, and the other end of the filter capacitor is connected with the ground.

As shown in fig. 2, the switched capacitor unit includes an intermediate positive level control module, an intermediate negative level control module, and a switched capacitor module;

the middle positive level control module is used for controlling 2E level generation;

the middle negative level control module is used for controlling-2E level generation;

the switched capacitor module is used for controlling the generation of + E or-E level;

one end of the middle positive level control module is connected with a connection point between a first capacitor C1 and a second capacitor C2; the other end is connected with the connection point between the first switch tube S1 and the second switch tube S2;

one end of the middle negative level control module is connected with a connection point between a first capacitor C3 and a second capacitor C4; the other end is connected with the connection point between the first switch tube S3 and the second switch tube S4;

one end of the switched capacitor module is connected with a connection point between a first capacitor C2 and a second capacitor C3; the other end is connected with the connection point between the first switch tube S2 and the second switch tube S3;

the middle positive level control module comprises a seventh switching tube and a diode; the collector of the seventh switching tube is connected with a connection point between a first capacitor C1 and a second capacitor C2; the emitter of the seventh switching tube is connected with the anode of a diode, and the cathode of the diode is connected with the connection point between the first switching tube S1 and the second switching tube S2;

the middle negative level control module comprises an eighth switching tube and a diode; the cathode of the diode is connected with the connection point between the third capacitor C3 and the fourth capacitor C4; the anode of the diode is connected with the emitter of an eighth switching tube, and the collector of the eighth switching tube is connected with the connection point between the third switching tube S3 and the fourth switching tube S4;

the switched capacitor module comprises a fifth switching tube S5, a sixth switching tube S6 and a flying capacitor C5;

an emitter of the fifth switching tube S5 is connected with the anode of the diode in series and then is connected with a connection point between the second capacitor C2 and the third capacitor C3 through the cathode of the diode; the collector of the fifth switching tube S5 is connected to the connection point between the first switching tube S1 and the second switching tube S2;

the collector of the sixth switching tube S6 is connected in series with the anode of the diode, and then connected to the connection point between the second capacitor C2 and the third capacitor C3 through the cathode of the diode; the collector of the sixth switching tube S6 is connected to the connection point between the third switching tube S3 and the fourth switching tube S4;

one end of the flying capacitor C5 is connected to the collector of the fifth switching tube S5, and the other end is connected to the emitter of the sixth switching tube S6.

How to obtain the nine-level mode is described in detail below according to the structure of the nine-level converter, which is as follows:

as shown in fig. 3, when only the first bidirectional switch and the second bidirectional switch are turned on, the output level of the circuit is 4E;

as shown in fig. 4, when only the first bidirectional switch and the third bidirectional switch are turned on, the output level of the circuit is 3E;

as shown in fig. 5, when only the middle positive level control module and the second bidirectional switch are turned on, the output level of the circuit is 2E;

as shown in fig. 6(a), when only the middle positive level control module and the third bidirectional switch are turned on, the output level of the circuit is E;

as shown in fig. 6(b), when only the sixth switch tube S6 and the second bidirectional switch are turned on, the output level of the circuit is E;

as shown in fig. 7(a), when only the sixth switching tube S6 and the third bidirectional switch are turned on, the circuit output level is 0;

as shown in fig. 7(b), when only the fifth switch tube S5 and the second bidirectional switch are turned on, the output level of the circuit is 0;

as shown in fig. 8(a), when only the fifth switch tube S5 and the third bidirectional switch are turned on, the output level of the circuit is-E;

as shown in fig. 8(b), when only the sixth switch tube S6 and the second bidirectional switch are turned on, the output level of the circuit is-E;

as shown in fig. 9, when only the middle negative level control module and the third bidirectional switch are turned on, the output level of the circuit is-2E;

as shown in fig. 10, when only the middle negative level control module and the second bidirectional switch are turned on, the output level of the circuit is-3E;

as shown in fig. 11, when only the middle negative level control module, the third bidirectional switch, and the fourth bidirectional switch are turned on, the circuit output level is-4E.

The circuit structure provided by the embodiment can combine with the addition of a flying capacitor in the circuit through a small number of fully-controlled switches, but the combination of the switches is changed greatly, so that a circuit with a brand-new function is formed, the simple circuit structure can also realize nine-level output, and the diversity of circuit change is increased.

In this embodiment, the switch tube is an IGBT, and is a composite fully-controlled voltage-driven power semiconductor device composed of a BJT (bipolar transistor) and an MOS (insulated gate field effect transistor).

Example 2

As shown in fig. 12, the middle positive level control module includes a seventh bidirectional switch and an eighth bidirectional switch connected in series; one end of the seventh bidirectional switch is connected with a connection point between the first capacitor C1 and the second capacitor C2; the other end of the first bidirectional switch is connected with one end of a second bidirectional switch, and the other end of the second bidirectional switch is connected with a connection point between the first switch tube S1 and the second switch tube S2;

the middle negative level control module comprises a ninth bidirectional switch and a tenth bidirectional switch which are connected in series; one end of the ninth bidirectional switch is connected with a connection point between a third capacitor C3 and a fourth capacitor C4; the other end of the first bidirectional switch is connected with one end of a third bidirectional switch, and the other end of the third bidirectional switch is connected with a connection point between the third switch tube S3 and the fourth switch tube S4;

the first to eighth bidirectional switches provided by this embodiment all adopt a switch tube and a diode connected in parallel, the anode of the diode is connected with the emitter of the switch tube as one end of the bidirectional switch tube, and the cathode of the diode is connected with the collector of the switch tube as the other end of the bidirectional switch tube.

The nine-level converter provided by the embodiment can generate nine output level modes of 4E, 3E, 2E, E, 0, -E, -2E, -3E and 4E by controlling the switched capacitor unit; the flying capacitor is obtained by adding and subtracting combination of series capacitors and flying capacitors. The circuit can be combined to obtain nine modes by only arranging one flying capacitor C5 on the basis of four capacitors, so that the mode change types are increased and the conversion efficiency of the circuit is improved under the condition that the number of fully-controlled switches is not increased basically.

The filter circuit provided by the embodiment can convert square waves close to sine waves into sine waves, and meets the requirement of the inverter for outputting sine waves. The switched capacitor module provided by the embodiment can be in various forms, for example, two or more capacitors can be combined in series and parallel, and more circuits can be generated.

The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.