阅读说明：本技术 一种能量可双向流动的多电平变换器 (Multi-level converter with energy capable of flowing bidirectionally ) 是由 吴军科 李辉 刘阳升 范兴明 于 2021-01-08 设计创作，主要内容包括：本发明公开了一种能量可双向流动的多电平变换器,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；所述开关电容单元包括中间正电平控制模块、中间负电平控制模块、开关电容模块、零电平控制模块；所述串联电容组中的各个电容分别通过中间正、负电平控制模块、开关电容模块和零电平控制模块的不同控制方式,产生九电平输出,本发明提供的能量可双向流动的多电平变换器,通过开关切换组合可以产生九电平的输出电压,该电路结构简单,可靠性高。(The invention discloses a multilevel converter with energy capable of bidirectionally flowing, 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; the switched capacitor unit comprises a middle positive level control module, a middle negative level control module, a switched capacitor module and a zero level control module; the multi-level converter with the energy capable of bidirectionally flowing can generate nine-level output voltage through switch switching combination, and the circuit is simple in structure and high in reliability.)

1. A bi-directional energy flow multilevel converter, comprising: the filter comprises a series capacitor bank, a series bidirectional switch bank, a switch capacitor unit and a filter circuit; the switched capacitor unit comprises a middle positive level control module, a middle negative level control module, a switched capacitor module and a zero level control module; the series capacitor bank comprises a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4; 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 capacitor C1 is connected to one end of a first switch tube S1, 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 a third capacitor C3, the other end of the third capacitor C3 is connected to one end of a fourth capacitor C4, and the other end of the fourth capacitor C4 is connected to the other end of a first switch tube S1;

one end of the first switching tube S1 is connected to one end of a first capacitor C1, 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 other end of a first capacitor C1;

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

one end of the switch capacitor module is connected with one end of the zero level control module, and the other end of the zero level control module is connected with a connection point between the first capacitor C2 and the second capacitor C3; the other end of the switched capacitor module is respectively connected with a connection point between the first switch tube S2 and the second switch tube S3, and a connection point between the third switch tube S3 and the fourth switch tube S4.

2. The energy bidirectional flow multilevel converter of claim 1, wherein: the zero 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 the first capacitor C2 and the second capacitor C3, the other end of the ninth bidirectional switch is connected with the tenth bidirectional switch, and the other end of the tenth bidirectional switch is connected with the switch capacitor module.

3. The energy bidirectional flow multilevel converter of claim 1, wherein: the middle positive level control module comprises a seventh bidirectional switch formed by a switching tube and a diode; the collector of the switching tube is connected with the cathode of the diode, the emitter of the switching tube is connected with the anode of the diode, and the collector of the switching tube is connected with the connection point between the first capacitor C1 and the second capacitor C2; and an emitting electrode of the switching tube is connected with one end of the switched capacitor module.

4. The energy bidirectional flow multilevel converter of claim 1, wherein: the middle negative level control module comprises an eighth bidirectional switch consisting of a switching tube and a diode; the collector of the switching tube is connected with the cathode of the diode, the emitter of the switching tube is connected with the anode of the diode, and the collector of the switching tube is connected with the connection point between the first capacitor C1 and the second capacitor C2; and the emitting electrode of the switch tube is connected with the other end of the switch capacitor module.

5. The energy bidirectional flow multilevel 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 emitting electrode of the fifth switching tube S5 is connected with the anode of the diode in series and then is connected with the middle positive level control module 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 with the anode of the diode in series and then is connected with the middle negative level control module 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.

6. The energy bidirectional flow multilevel 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.

7. The energy bidirectional flow multilevel 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.

Technical Field

The invention relates to the technical field related to electric energy conversion, in particular to a multi-level converter with energy capable of bidirectionally flowing.

Background

As distributed generation has increased in the power system, power converters have become an important interface for connecting distributed power sources to large power grids. In an alternating current-direct current hybrid micro-grid, an electric energy conversion device with energy flowing bidirectionally plays an important role in guaranteeing power balance of a grid and realizing harmonic control on an alternating current side. Compared with the traditional two-level converter, the multi-level converter can reduce the harmonic waves on the alternating current side. Therefore, how to combine the multilevel technology with the bidirectional power conversion circuit to find more electric energy conversion devices suitable for the ac/dc hybrid microgrid is a topic worthy of research.

Disclosure of Invention

In view of the above, the present invention provides a multilevel converter with bidirectional energy flow, which has a simple structure and can realize nine-level output.

The invention provides an energy bidirectional flow multilevel 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 comprises a capacitor, a capacitor and a capacitor; the switched capacitor unit comprises a middle positive level control module, a middle negative level control module, a switched capacitor module and a zero level control module; the series capacitor bank comprises a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4; 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 capacitor C1 is connected to one end of a first switch tube S1, 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 a third capacitor C3, the other end of the third capacitor C3 is connected to one end of a fourth capacitor C4, and the other end of the fourth capacitor C4 is connected to the other end of a first switch tube S1;

one end of the first switching tube S1 is connected to one end of a first capacitor C1, 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 other end of a first capacitor C1;

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

one end of the switch capacitor module is connected with one end of the zero level control module, and the other end of the zero level control module is connected with a connection point between the first capacitor C2 and the second capacitor C3; the other end of the switched capacitor module is respectively connected with a connection point between the first switch tube S2 and the second switch tube S3, and a connection point between the third switch tube S3 and the fourth switch tube S4.

Further, the zero 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 the first capacitor C2 and the second capacitor C3, the other end of the ninth bidirectional switch is connected with the tenth bidirectional switch, and the other end of the tenth bidirectional switch is connected with the switched capacitor module.

Further, the middle positive level control module comprises a seventh bidirectional switch composed of a switching tube and a diode; the collector of the switching tube is connected with the cathode of the diode, the emitter of the switching tube is connected with the anode of the diode, and the collector of the switching tube is connected with the connection point between the first capacitor C1 and the second capacitor C2; and an emitting electrode of the switching tube is connected with one end of the switched capacitor module.

Further, the middle negative level control module comprises an eighth bidirectional switch formed by a switching tube and a diode; the collector of the switching tube is connected with the cathode of the diode, the emitter of the switching tube is connected with the anode of the diode, and the collector of the switching tube is connected with the connection point between the first capacitor C1 and the second capacitor C2; and the emitting electrode of the switch tube is connected with the other end of the switch capacitor module.

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

an emitting electrode of the fifth switching tube S5 is connected with the anode of the diode in series and then is connected with the middle positive level control module 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 with the anode of the diode in series and then is connected with the middle negative level control module 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.

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.

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.

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

the invention has the beneficial effects that:

the energy bidirectional flow multilevel converter provided by the invention can generate nine-level output voltage under the condition of less switching elements and capacitors through the control combination of the switching unit and the switched capacitor unit, and meanwhile, the circuit can realize bidirectional conversion of power, thereby reducing the cost of the converter, simplifying the structure of the converter and enabling the performance of the converter to be 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 multilevel converter with bi-directional energy flow.

Fig. 2a is a schematic diagram of a current path with a positive current direction at an output level of 4E.

Fig. 2b is a schematic diagram of the current path with a negative current direction at an output level of 4E.

FIG. 3a is a schematic diagram of a current path with a positive current direction at an output level of 3E.

FIG. 3b is a schematic diagram of the current path with a negative current direction at an output level of 3E.

FIG. 4a is a schematic diagram of a current path with a positive current direction at an output level of 2E.

FIG. 4b is a schematic diagram of the current path with a negative current direction at an output level of 2E.

FIG. 5a is a schematic diagram of a current path with a positive current direction at an output level E.

FIG. 5b is a schematic diagram of the current path with a positive current direction at the output level E.

FIG. 6a is a schematic diagram of a current path with a positive current direction at an output level of 0.

FIG. 6b is a schematic diagram of the current path with a positive current direction at an output level of 0.

FIG. 7a is a schematic diagram of a current path with a positive current direction at an output level of-E.

FIG. 7b is a schematic diagram of the current path with the current direction being positive at an output level of-E.

FIG. 8a is a schematic diagram of a current path with a positive current direction at an output level of-2E.

FIG. 8b is a schematic diagram of the current path with negative current direction at an output level of-2E.

FIG. 9a is a schematic diagram of a current path with a positive current direction at an output level of-3E.

FIG. 9b is a schematic diagram of the current path with negative current direction at an output level of-3E.

FIG. 10a is a schematic diagram of a current path with a positive current direction at an output level of-4E.

FIG. 10b is a schematic diagram of the current path with negative current direction at an output level of-4E.

In the figure, 1 denotes a series capacitor bank, 2 denotes a series bidirectional switch bank, 31 denotes an intermediate positive level control module, 32 denotes an intermediate negative level control module, 33 denotes a switched capacitor module, 34 denotes a zero level control module, and 4 denotes a filter circuit.

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.

As shown in fig. 1, the present embodiment provides a multilevel converter with bidirectional energy flow, which 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.

The switched capacitor unit comprises a middle positive level control module, a middle negative level control module, a switched capacitor module and a zero level control 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;

the zero level control module is used for controlling zero level generation;

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 of the switch capacitor module is connected with one end of the switch capacitor module, and the other end of the switch capacitor module is connected with a 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 of the switch capacitor module is connected with one end of the switch capacitor module, and the other end of the switch capacitor module is connected with a connection point between the first switch tube S3 and the second switch tube S4;

one end of the switch capacitor module is connected with one end of the zero level control module, and the other end of the zero level control module is connected with a connection point between the first capacitor C2 and the second capacitor C3; the other end of the switched capacitor module is respectively connected with a connection point between the first switching tube S2 and the second switching tube S3 and a connection point between the third switching tube S3 and the fourth switching tube S4;

the middle positive level control module comprises a seventh bidirectional switch formed by a switching tube and a diode; the collector of the switching tube is connected with the cathode of the diode, the emitter of the switching tube is connected with the anode of the diode, and the collector of the switching tube is connected with the connection point between the first capacitor C1 and the second capacitor C2; the emitting electrode of the switch tube is connected with one end of the switch capacitor module;

the middle negative level control module comprises an eighth bidirectional switch consisting of a switching tube and a diode; the collector of the switching tube is connected with the cathode of the diode, the emitter of the switching tube is connected with the anode of the diode, and the collector of the switching tube is connected with the connection point between the first capacitor C1 and the second capacitor C2; the emitting electrode of the switch tube is connected with the other end of the switch capacitor module;

the zero 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 first capacitor C2 and a second capacitor C3, the other end of the ninth bidirectional switch is connected with the tenth bidirectional switch, and the other end of the tenth bidirectional switch is connected with the switched capacitor module;

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

an emitting electrode of the fifth switching tube S5 is connected with the anode of the diode in series and then is connected with the middle positive level control module 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 with the anode of the diode in series and then is connected with the middle negative level control module 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 with the collector of the fifth switch tube S5, and the other end is connected with the emitter of the sixth switch tube S6;

the multi-level converter with bidirectional energy flow provided by the embodiment can generate nine output level modes of 4E, 3E, 2E, E, 0, -E, -2E, -3E and 4E through the control of 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 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).

The working process of the energy bidirectional flow multilevel converter is described in detail below, with the inductor current iL facing to the right as a positive reference direction:

as shown in fig. 2a and fig. 2b, when the level of the point O is 4E, when the inductor current iL is positive (fig. 2a), the gate driving signals of the fully-controlled switches S1 and S2 are high, the switches are turned on, and the circuit is in an inversion state; when the inductor current iL is negative (fig. b), the anti-parallel diodes of S1 and S2 are turned on and the circuit is in a rectifying state.

As shown in fig. 3a and fig. 3b, when the level of the point O is 3E, when the inductor current iL is positive (fig. 3a), the fully controlled switch S1 is turned on, the anti-parallel diode of S3 is turned on, and the circuit is in an inversion state; when the inductor current iL is negative (fig. 3b), the fully-controlled switch S3 is turned on, the anti-parallel diode of S1 is turned on, and the circuit is in a rectifying state;

as shown in fig. 4a and 4b, when the level of the point O is 2E, when the inductor current iL is positive (fig. 4a), the fully-controlled switches S6 and S7 are turned on, the anti-parallel diode of S3 is turned on, and the circuit is in an inversion state; when the inductor current iL is negative (fig. 4b), the fully-controlled switch S5 is turned on, the anti-parallel diodes of S2 and S7 are turned on, and the circuit is in a rectification state;

as shown in fig. 5a and 5b, when the point O is at E level, when the inductor current iL is positive (fig. 5a), the fully-controlled switches S2, S6 and S9 are turned on, the anti-parallel diode of S10 is turned on, and the circuit is in an inverted state; when the inductor current iL is negative (fig. 5b), the fully-controlled switches S3 and S5 are turned on, the anti-parallel diode of S7 is turned on, and the circuit is in a rectification state;

as shown in fig. 6a and 6b, when the O point is at 0 level, the inductor is in a freewheeling state, when the inductor current iL is positive (fig. 6a), the fully-controlled switches S6 and S9 are turned on, and the anti-parallel diodes of S3 and S10 are turned on; when the inductor current iL is negative (fig. 6b), the fully-controlled switches S5 and S10 are turned on, and the anti-parallel diode of S2 and S9 are turned on;

as shown in fig. 7a and 7b, when the point O is at-E level, when the inductor current iL is positive (fig. 7a), the fully-controlled switches S2 and S6 are turned on, the anti-parallel diode of S8 is turned on, and the circuit is in an inverting state; when the inductor current iL is negative (fig. 7b), the fully-controlled switches S3, S5 and S10 are turned on, the anti-parallel diode of S9 is turned on, and the circuit is in a rectification state;

as shown in fig. 8a and 8b, when the point O is at-2E level, when the inductor current iL is positive (fig. 8a), the fully-controlled switch S6 is turned on, the anti-parallel diodes of S3 and S8 are turned on, and the circuit is in an inversion state; when the inductor current iL is negative (fig. 8b), the fully-controlled switches S5 and S8 are turned on, the anti-parallel diode of S2 is turned on, and the circuit is in a rectification state;

as shown in fig. 9a and 9b, when the point O is at-3E level, when the inductor current iL is positive (fig. 9a), the fully-controlled switch S2 is turned on, the anti-parallel diode of S4 is turned on, and the circuit is in an inverting state; when the inductor current iL is negative (fig. 9b), the fully-controlled switches S3, S5 and S8 are turned on, and the circuit is in a rectifying state;

as shown in fig. 10a and 10b, when the point O is at-4E level, when the inductor current iL is positive (fig. 10a), the anti-parallel diodes of S3 and S4 are turned on, and the circuit is in an inverted state; when the inductor current iL is negative (fig. 10b), the fully controlled switches S3 and S4 are turned on, and the circuit is in a rectifying state.

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.