WO2021159873A1

WO2021159873A1 - Bidirectional energy balance converter chain, electric energy router, and control method

Info

Publication number: WO2021159873A1
Application number: PCT/CN2020/140665
Authority: WO
Inventors: 谢晔源; 王宇; 李海英; 孙乐
Original assignee: 南京南瑞继保电气有限公司; 南京南瑞继保工程技术有限公司
Priority date: 2020-02-13
Filing date: 2020-12-29
Publication date: 2021-08-19
Also published as: CN113258794B; CN113258794A

Abstract

The present application provides a bidirectional energy balance converter chain, comprising M power units. The M power units each comprise two alternating-current terminals, and the alternating-current terminals of adjacent power units are sequentially connected in series. There are N multi-port balancing units, N being an integer greater than or equal to 1 and less than or equal to M; the number P of ports of the multi-port balancing units is 3 or 4; when P is 3, the multi-port balancing units each comprise first, second, and third ports, and the third port is connected to a positive electrode or negative electrode of a first direct-current capacitor; when P is 4, the multi-port balancing units each comprise first, second, third, and fourth ports; the first port of the multi-port balancing unit at a head end leads out and is defined as a first balancing port, and the second port is connected to the first port of the multi-port balancing unit adjacent thereto; the remaining ports are sequentially connected in this manner; the second port of the multi-port balancing unit at a tail end leads out and is defined as a second balancing port. The present invention further provides an energy router consisting of the bidirectional energy balance converter chain, and a control method.

Description

Two-way energy balance commutation chain, electric energy router and control method

Technical field

This application relates to the field of power electronics technology, and in particular to a two-way energy balance converter chain, an electric energy router, and a control method.

Background technique

With the development of modern power electronic technology, due to the relatively limited withstand voltage level of single-tube power semiconductor devices, its application and development have been greatly restricted.

Power semiconductor devices are composed of sub-modules (or power units), and then cascaded to form a converter chain, which can easily meet the voltage level requirements of the module. Compared with other solutions, it is a cost-effective way. However, once the converter chain is subjected to overvoltage, or there is a problem of voltage unevenness between the sub-modules of the converter chain, the voltage of individual sub-modules will be too high, or even damaged due to overvoltage. The expansion of the fault will cause the entire converter chain to malfunction and damage.

In the prior art, there is a way to increase the device connection between the modules. For example, in the patent CN105471260A, the auxiliary capacitor distributed half-bridge MMC self-balancing topology based on equation constraints is used to establish the charging between the sub-module DC capacitors. The discharge channel uses the auxiliary circuit between the three-phase bridge arms to achieve the function of DC voltage balance control, but the disadvantages of this method are: first, when a single sub-module fails, even if the bypass switch of the power unit is closed, the auxiliary The circuit will still maintain the connection relationship between the normal module and the faulty module. For example, when there is a short circuit on the DC side of a sub-module, the DC capacitors of the adjacent sub-modules will discharge to the fault point through the auxiliary circuit. If the auxiliary circuit is simply disconnected by the switch, the auxiliary circuit will be opened, and the auxiliary balance circuit of the entire converter chain will be disconnected here. Therefore, the reliability of the scheme is low and the project feasibility is poor; second, The DC voltage of this scheme can only be balanced in one direction, and the charging and discharging direction is irreversible. It is required that the equalization circuit of the commutation chain must form a closed loop, which is difficult to achieve in many topologies, and the above-mentioned methods are greatly restricted in application.

In order to better balance the voltage between the various sub-modules of the converter chain and prevent the sub-modules from being affected by instantaneous overvoltages, only the capacitance value of the sub-modules can be increased, or the number of sub-modules can be increased greatly. It reduces the cost and land occupation of the entire converter chain.

Summary of the invention

The purpose of the present invention is to provide a two-way energy balance commutation chain, which can realize energy balance in both directions of the commutation chain through a multi-port balance unit, and realize DC voltage balance control. At the same time, when a single power unit fails bypass, The faulty power unit can be removed from the converter chain without affecting the normal operation of the multi-port balance unit of other power units in the converter chain, and the capacitance value of the DC capacitor in the power unit can be reduced. The present invention also provides an energy router composed of the above-mentioned two-way energy balance commutation chain and a control method.

In order to achieve the above objective, the solution of the present invention is:

A two-way energy balance commutation chain, including:

M power units, the M power units include two AC terminals, the AC terminals of adjacent power units are sequentially connected in series, the empty port of the head-end power unit is defined as the first power port, and the empty port of the tail-end power unit Leading out is defined as the second power port; the power unit includes a first DC capacitor and a power component connected in parallel, and M is an integer greater than or equal to 1;

N multi-port balance units, N is an integer greater than or equal to 1 and less than or equal to M;

The number P of the ports of the multi-port balance unit is 3 or 4;

When P=3, the multi-port balancing unit includes first, second, and third ports, and the third port is connected to the positive or negative pole of the first DC capacitor; when P=4, the multi-port balancing unit includes first, Two, three and four ports, the third port is connected to the positive pole of the DC capacitor, and the fourth port is connected to the negative pole of the DC capacitor; or the third port is connected to the negative pole of the DC capacitor, and the fourth port is connected to the positive pole of the DC capacitor;

The first port of the head end multi-port balance unit is defined as the first balance port, the second port is connected to the first port of the adjacent multi-port balance unit, and is connected in this way. The second port of the tail end multi-port balance unit The port lead is defined as the second balanced port.

As a further preferred solution of the present invention, the multi-port balance unit in the bidirectional energy balance commutation chain is used to control the charging and discharging between the first DC capacitors of adjacent power units.

As a further preferred solution of the present invention, the bidirectional energy balance commutation chain further includes a first bypass switch, and the first bypass switch is connected in parallel between the first port and the second port of the multi-port balance unit.

As a further preferred solution of the present invention, P=4, the multi-port balance unit includes first, second, third, and fourth switch units, and one end of the first and second switch units are respectively connected to the first and second ports; The other ends of the two switch units are connected to the third port after being connected; one ends of the third and fourth switch units are respectively connected to the first and second ports, and the other end is connected to the fourth port.

As a further preferred solution of the present invention, P=3, the multi-port balance unit includes first and second switch units, one end of the first and second switch units are respectively connected to the first and second ports; the first switch unit and the second switch unit The other end of the switch unit is connected to the third port.

As a further preferred solution of the present invention, P=4, the multi-port balance unit includes first, second, and third switch units, one end of the first and second switch units are connected to the first and second ports respectively; the first switch unit is connected to The other end of the second switch unit is connected to the third port after being connected; one end of the third switch unit is connected to the first port or the second port, and the other end is connected to the fourth port.

As a further preferred solution of the present invention, P=3, the multi-port balance unit includes first and second switch units, one end of the first and second switch units are respectively connected to the first and second ports; the other end of the first switch unit It is connected to the second port, and the other end of the second switch unit is connected to the third port.

As a further preferred solution of the present invention, P=4, the multi-port balance unit includes first, second, and third switch units, one end of the first and second switch units are connected to the first and second ports respectively; The other end is connected to the second port, the other end of the second switch unit is connected to the third port, one end of the third switch unit is connected to the second port or the first port, and the other end is connected to the fourth port.

As a further preferred solution of the present invention, P=3, the multi-port balance unit includes a first switch unit, one end of the first switch unit is connected to the first port and the third port at the same time, and the other end is connected to the second port.

As a further preferred solution of the present invention, each switch unit in the bidirectional energy balance commutation chain includes a power semiconductor device or a mechanical switch.

As a further preferred solution of the present invention, each switch unit in the bidirectional energy balance commutation chain further includes a current-limiting unit composed of a current-limiting resistor, an inductor, a fuse, or any combination of the three devices, and the current-limiting unit is connected to the current-limiting unit. The power semiconductor devices or mechanical switches in the switching unit are connected in series.

As a further preferred solution of the present invention, the bidirectional energy balance commutation chain further includes an isolating switch group, which is connected in series between the third and fourth ports and the positive and negative electrodes of the first DC capacitor; when P=3 The switch group includes one switch, and when P=4, the switch group includes at least one switch.

As a further preferred solution of the present invention, the power component in the power unit is composed of two fully-controlled power semiconductor devices in the form of half-bridge connection, or four fully-controlled power semiconductor devices in the form of full-bridge connection, or It is composed of a fully-controlled power semiconductor device in parallel with a buffer circuit, and the buffer circuit is composed of a diode and a capacitor in series.

As a further preferred solution of the present invention, the converter chain further includes at least one protection unit, the protection unit includes a protection resistor and a protection switch, connected in series at any position in the converter chain or connected in parallel at both ends of the first DC capacitor .

As a further preferred solution of the present invention, the protection unit includes a first protection switch and a first protection resistor, and the first protection switch and the first protection resistor are connected in parallel; wherein the first protection switch is connected in reverse direction with two anti-parallel connections. The diode IGBT is connected in series with the mechanical switch.

As a further preferred solution of the present invention, the protection unit further includes a second protection switch, a second protection resistor, and a second DC capacitor; after the second DC capacitor is connected in series with the second protection switch and the second protection resistor, it is connected to the first The protection resistor and the first protection switch are connected in parallel.

As a further preferred solution of the present invention, the protection unit includes a second protection switch and a second protection resistor. After the second protection switch and the second protection resistor are connected in series, they are connected in parallel to both ends of the first DC capacitor.

As a further preferred solution of the present invention, the power unit further includes: a second bypass switch connected in parallel to the AC end of the power unit.

As a further preferred solution of the present invention, the bidirectional energy balance commutation chain further includes: at least one DC port connected to the positive and negative electrodes of the first DC capacitor; and the DC port is used to connect to the DC side of the converter unit or Lead out as a backup port.

The present invention also provides an electrical energy router, which includes at least three bidirectional energy balance commutation chains as described above.

As a further preferred solution of the present invention, the electrical energy router further includes K converter units, K is an integer greater than or equal to 1 and less than or equal to M, the input end of the converter unit is connected to the positive and negative electrodes of the first DC capacitor, and the output The load or power supply is terminated, and there is an isolation unit between the input end and the output end of the converter unit.

As a further preferred solution of the present invention, the electrical energy router has a DC positive pole and a DC negative pole, wherein the electrical energy router includes six bidirectional energy balance converter chains to form a three-phase upper bridge arm and a three-phase lower bridge arm; The first power port of the bridge arm converter chain is connected to the DC positive pole, and the second power port of the upper bridge arm converter chain of the same phase is connected to the first power port of the lower bridge arm converter chain; the three-phase lower bridge arm converter chain The second power port of is connected with the DC negative pole; the second power port of the three-phase upper bridge arm converter chain is led out as the AC terminal of the electric energy router.

As a further preferred solution of the present invention, the first balanced ports of the three-phase upper-arm converter chain of the electric energy router are connected together, and the second balanced ports of the three-phase lower-arm converter chain of the electric energy router are connected to Together.

As a further preferred solution of the present invention, the second balance port of the in-phase upper bridge arm converter chain of the electric energy router is connected to the first balance port of the lower bridge arm converter chain.

As a further preferred solution of the present invention, the electric energy router includes three bidirectional energy balance converter chains, the first power ports of the three converter chains are connected together, and the second power ports are respectively connected to the ABC three phases of the power grid; Or the second power ports of the three converter chains are connected together, and the first power ports are respectively connected to the ABC three phases of the power grid.

As a further preferred solution of the present invention, the first power ports of the three converter chains are connected together, the first balanced ports are connected together, and the second power ports are respectively connected to the ABC three phases of the power grid; or the three The second power ports of the two converter chains are connected together, and the second balance ports are connected together, and the first power ports are respectively connected to the ABC three phases of the power grid.

As a further preferred solution of the present invention, the electric energy router includes three bidirectional energy balance converter chains, the first power port of the converter chain and the second power port of the adjacent converter chain are connected to each other to form a closed loop; The first power port or the second power port of the flow link is respectively connected to the ABC three phases of the power grid, forming an angular connection mode.

As a further preferred solution of the present invention, the first balance ports of the three converter chains and the second balance ports of the adjacent converter chains are connected to each other to form a closed loop.

The present invention also provides a method for controlling the above-mentioned two-way energy balance commutation chain, which includes:

When the DC voltage of the power units in the bidirectional energy balance converter chain is uneven, by controlling the switching units in the multi-port balance unit, a circuit for charging and discharging the first DC capacitor between adjacent power units is established to maintain the DC of the power unit. Voltage balance

When the DC capacitor voltage of any power unit is higher than the DC capacitor voltage of the adjacent power unit, the DC capacitor with a higher voltage is discharged to the DC capacitor of the adjacent power unit through the multi-port balance unit connected to the power unit.

As a further preferred solution of the present invention, when the power unit fails, the second bypass switch in the power unit is closed, and the first bypass switch is closed at the same time.

Beneficial effects:

The technical solution provided by this application can realize the charge and discharge control of the adjacent power units of the converter chain in two directions through the cooperation of the switch unit in the multi-port balance unit and the power semiconductor devices in the power assembly, so as to ensure that each converter chain The DC capacitor voltage of the power unit is balanced. When the power unit fails, the failed power unit and the corresponding multi-port balance unit can be bypassed without affecting the connection loop before the multi-port balance unit of the converter chain. The added multi-port balance unit does not need to flow a large current, and can be realized by only adding a small cost.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings that need to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

FIG. 1A is one of the schematic diagrams of a two-way energy balance commutation chain provided by an embodiment of the present application;

FIG. 1B is the second schematic diagram of the structure of a two-way energy balance commutation chain provided by an embodiment of the present application;

FIG. 1C is the third schematic diagram of the structure of a two-way energy balance commutation chain provided by an embodiment of the present application;

2 is a schematic diagram of the structure of a bidirectional energy balance commutation chain with a protection unit provided by an embodiment of the present application;

3A is one of the schematic diagrams of the structure of a multi-port balance unit provided by an embodiment of the present application;

3B is the second schematic diagram of the structure of a multi-port balance unit provided by an embodiment of the present application;

3C is the third schematic diagram of the structure of the multi-port balance unit provided by the embodiment of the present application;

3D is the fourth schematic diagram of the structure of the multi-port balance unit provided by the embodiment of the present application;

3E is the fifth schematic diagram of the structure of the multi-port balance unit provided by the embodiment of the present application;

3F is a sixth schematic diagram of the structure of a multi-port balance unit provided by an embodiment of the present application;

3G is the seventh schematic diagram of the structure of the multi-port balance unit provided by the embodiment of the present application;

3H is the eighth schematic diagram of the structure of a multi-port balance unit provided by an embodiment of the present application;

FIG. 3I is a ninth schematic diagram of the structure of a multi-port balance unit provided by an embodiment of the present application;

3J is the tenth schematic diagram of the structure of the multi-port balance unit provided by the embodiment of the present application;

FIG. 4A is one of the schematic diagrams of the structure of the power unit provided by the embodiment of the present application;

4B is the second schematic diagram of the structure of the power unit provided by the embodiment of the present application;

4C is the third schematic diagram of the structure of the power unit provided by the embodiment of the present application;

FIG. 5A is one of the schematic diagrams of the structure of the protection unit provided by the embodiment of the present application;

FIG. 5B is the second schematic diagram of the structure of the protection unit provided by the embodiment of the present application;

5C is the third schematic diagram of the structure of the protection unit provided by the embodiment of the present application;

Fig. 6 is a schematic diagram of the structure of a bidirectional energy-balanced converter chain with converter units provided by an embodiment of the present application

FIG. 7A is one of the schematic diagrams of the structure of an electric energy router provided by an embodiment of the present application;

FIG. 7B is the second schematic diagram of the structure of the electric energy router provided by the embodiment of the present application;

FIG. 7C is the third schematic diagram of the structure of the electric energy router provided by the embodiment of the present application;

Detailed ways

The technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative work shall fall within the protection scope of this application.

It should be understood that the terms "first", "second", "third", "fourth", etc. in the claims, specification and drawings of this application are used to distinguish different objects, rather than to describe a specific sequence. . The term "comprising" used in the specification and claims of this application indicates the existence of the described features, wholes, steps, operations, elements and/or components, but does not exclude one or more other features, wholes, steps, operations , The presence or addition of elements, components, and/or collections thereof.

The present invention provides a bidirectional energy balance converter chain 1, as shown in Fig. 1A, including:

M power units 2, the M power units include two AC terminals, the AC terminals of adjacent power units are sequentially connected in series, the empty port of the head end power unit is defined as the first power port D1, and the end power unit's The empty port lead is defined as the second power port D2; the power unit includes a first DC capacitor and a power component connected in parallel, and M is an integer greater than or equal to 1;

N multi-port balance units 3, where N is an integer greater than or equal to 1 and less than or equal to M;

The number P of the ports of the multi-port balance unit is 3 or 4;

The first port of the head end multi-port balance unit is defined as the first balance port H1, the second port is connected to the first port of the adjacent multi-port balance unit, and is connected in this way. The two-port lead is defined as the second balanced port H2.

Wherein, the bidirectional energy balance commutation chain further includes a first bypass switch 4, which is connected in parallel between the first port and the second port of the multi-port balance unit.

The multi-port balance unit in the bidirectional energy balance commutation chain is used to control the charging and discharging between the first DC capacitors of adjacent power units.

The multi-port balance unit of the present invention has a variety of composition forms:

(1) Where P=4, the multi-port balance unit includes first, second, third, and fourth switch units, one end of the first and second switch units are connected to the first and second ports respectively; the first and second switch units The other end of the switch unit is connected to the third port after being connected; one end of the third and fourth switch units is connected to the first port and the second port respectively, and the other end is connected to the fourth port.

As shown in FIG. 3A, in this embodiment, the four switching units are respectively IGBTs with anti-parallel diodes, forming an H-bridge circuit. The emitters of the first and second switching unit IGBTs are connected to the first and second ports respectively; the collectors of the first and second switching unit IGBTs are connected to the third port after being connected; the collectors of the third and fourth switching unit IGBTs are connected to the third port respectively. The first and second ports are connected, and the emitter is connected to the fourth port.

As shown in FIG. 3B, in this embodiment, the first and second switch units are respectively IGBTs with anti-parallel diodes, and the third and fourth switch units are respectively diodes to form an H-bridge circuit. The collectors of the first and second switching unit IGBTs are connected to the first and second ports respectively; the emitters of the first and second switching unit IGBTs are connected to the third port after being connected; the cathodes of the third and fourth switching unit diodes are respectively connected to the first , The second port is connected, and the anode is connected to the fourth port.

(2) Where P=3, the multi-port balance unit includes first and second switch units, one end of the first and second switch units are respectively connected to the first and second ports; the first switch unit and the second switch unit After the other end is connected, it is connected to the third port.

As shown in FIG. 3C, in this embodiment, the two switching units are respectively IGBTs with anti-parallel diodes. The collectors of the first and second switch units IGBT are connected to the first and second ports respectively; the emitters of the first and second switch units IGBT are connected to the third port after being connected.

(3) Where P=4, the multi-port balance unit includes first, second, and third switch units, one end of the first and second switch units are respectively connected to the first and second ports; the first switch unit and the second switch The other end of the unit is connected to the third port after being connected; one end of the third switch unit is connected to the first port or the second port, and the other end is connected to the fourth port.

As shown in FIG. 3D, in this embodiment, the first and second switch units are IGBTs with anti-parallel diodes, the third switch unit is a diode, the cathode of the diode is connected to the second port, and the anode is connected to the fourth port.

(4) Where P=3, the multi-port balance unit includes first and second switch units, one end of the first and second switch units are connected to the first and second ports respectively; the other end of the first switch unit is connected to the second The port is connected, and the other end of the second switch unit is connected to the third port.

As shown in Figure 3E, in this embodiment, the first and second switching units are IGBTs with anti-parallel diodes, the collector of the first switching unit IGBT is connected to the first port, and the emitter of the IGBT is connected to the second switching unit. The collector of the IGBT is connected to the second port, and the emitter of the second switching unit IGBT is connected to the third port.

(5) Where P=4, the multi-port balance unit includes first, second, and third switch units, one end of the first and second switch units are respectively connected to the first and second ports; the other end of the first switch unit is connected to the The second port is connected, the other end of the second switch unit is connected to the third port, one end of the third switch unit is connected to the second port or the first port, and the other end is connected to the fourth port.

As shown in Figure 3F, in this embodiment, the first and second switch units are IGBTs with anti-parallel diodes, the third switch unit is a diode, the collector of the first switch unit IGBT is connected to the first port, and the IGBT's The emitter is connected to the collector of the second switching unit IGBT and connected to the second port. The emitter of the second switching unit IGBT is connected to the third port; the cathode of the diode of the third switching unit is connected to the second port, and the anode is connected to the second port. Four-port connection.

(6) Where P=3, the multi-port balance unit includes a first switch unit, one end of the first switch unit is connected to the first port and the third port at the same time, and the other end is connected to the second port.

As shown in Figure 3G, in this embodiment, the first switching unit is an IGBT with an anti-parallel diode, the collector of the first switching unit IGBT is connected to the first port and the third port at the same time, and the emitter is connected to the second port. .

The first, second, third, and fourth switch units in the above-mentioned connection modes (1)-(6) may include unidirectional cut-off power semiconductor devices such as IGBTs with anti-parallel diodes, diodes, or bidirectional as shown in Figure 3H Cut-off power semiconductor devices. The first, second, third, and fourth switch units may also include fast mechanical switches.

The first, second, third, and fourth switch units in the two-way energy balance commutation chain may also include a current-limiting unit composed of a current-limiting resistor, an inductor, a fuse, or any combination of the three devices, and the current-limiting unit is connected to the current-limiting unit. The power semiconductor devices or mechanical switches in the switching unit are connected in series.

As shown in FIG. 3I, in this embodiment, the second switching unit not only includes an IGBT with an anti-parallel diode, but also includes a current limiting resistor 14, an inductor 15 and a fuse 13 connected in series. The above three devices can be combined arbitrarily.

Wherein, the two-way energy balance commutation chain further includes an isolation switch group, which is connected in series between the third and fourth ports and the positive and negative electrodes of the first DC capacitor; when P=3, the switch group includes 1 switch, when P=4, the switch group includes 2 switches.

As shown in FIG. 3J, in this embodiment, the third port of the multi-port balance unit is connected to the anode of the first DC capacitor through an isolating switch 12.

Among them, the power components in the power unit described in this example are constructed in three ways:

(1) Two fully-controlled power semiconductor devices are constructed in the form of half-bridge connection, as shown in Fig. 4A. Two of the fully-controlled power semiconductor devices are IGBTs with anti-parallel diodes, respectively T1 and T2. The collector of T1 is connected to the anode of the first DC capacitor C1, the collector of T2 is connected to the emitter of T1, and T2 The emitter of C1 is connected to the negative pole of C1, and the emitter of T1 and T2 are led out as two AC terminals of the power unit.

(2) It is composed of four full-control power semiconductor devices in the form of full-bridge connection, as shown in Fig. 4B. The four fully-controlled power semiconductor devices are IGBTs with anti-parallel diodes, respectively T3-T6. T3 and T4 form one bridge arm, and T5 and T6 form another bridge arm: the collector of T3 and the first The anode of the DC capacitor C1 is connected, the collector of T4 is connected to the emitter of T3, the emitter of T4 is connected to the cathode of C1; the collector of T5 is connected to the anode of the first DC capacitor C1, and the collector of T6 is connected to the emitter of T5 Pole connection, the emitter of T6 is connected to the negative pole of C1; the midpoint of the two bridge arms leads to the two AC terminals of the power unit.

(3) It is composed of a fully-controlled power semiconductor device in parallel with a buffer circuit, and the buffer circuit is composed of a diode and a capacitor in series, as shown in FIG. 4C. The collector of the fully-controlled power semiconductor device T7 is connected to the anode of the first DC capacitor C1 through the diode D1, and the emitter of T7 is connected to the cathode of the first DC capacitor C1.

Wherein, the converter chain further includes at least one protection unit 6, and the protection unit includes a protection resistor and a protection switch, which are connected in series at any position in the converter chain or connected in parallel to both ends of the first DC capacitor. There are several ways of composition:

(1) As shown in FIG. 5A, in this embodiment, the first protection switch 8 and the first protection resistor 11 are formed, and the first protection switch and the first protection resistor are connected in parallel. The first protection switch is composed of two IGBTs with anti-parallel diodes connected in series in opposite directions and a mechanical switch in series.

(2) As shown in FIG. 5B, in this embodiment, the protection unit includes a second protection switch 9, a second protection resistor 10, and a second DC capacitor C2 in addition to the first protection switch 8 and the first protection resistor 11 After the second DC capacitor is connected in series with the second protection switch and the second protection resistor, it is connected in parallel with the first protection resistor and the first protection switch.

(3) As shown in Figure 5C, in this embodiment, the protection unit includes a second protection switch 9 and a second protection resistor 10. After the second protection switch and the second protection resistor are connected in series, they are connected in parallel with the two first DC capacitors. end.

FIG. 2 is a schematic diagram of the structure of a bidirectional energy balance commutation chain with a protection unit provided by an embodiment of the application.

As shown in Fig. 1A, the power unit further includes: a second bypass switch 5 connected in parallel to the AC end of the power unit.

FIG. 1A is one of the schematic diagrams of the structure of a bidirectional energy balance commutation chain provided by an embodiment of the present application; in this embodiment, the multi-port balance unit is the structure shown in FIG. 3A, and the power unit is the structure shown in FIG. 4B.

FIG. 1B is the second schematic diagram of the structure of a bidirectional energy balancing commutation chain provided by an embodiment of the present application; in this embodiment, the multi-port balancing unit is the structure shown in FIG. 3H, and the power unit is the structure shown in FIG. 4A.

FIG. 1C is the third schematic diagram of the structure of a two-way energy balancing commutation chain provided by an embodiment of the present application; in this embodiment, the multi-port balancing unit is the structure shown in FIG. 3G, and the power unit is the structure shown in FIG. 4C.

The bidirectional energy balance commutation chain of this embodiment further includes at least one DC port connected to the anode and cathode of the first DC capacitor; the DC port is used to connect to the DC side of the converter unit or lead out as a backup port. As shown in FIG. 6, after the positive and negative poles of the first DC capacitor are led out, they are connected to the DC converter unit 20.

The bidirectional energy balance commutation chain of the present invention can constitute an electric energy router, and the electric energy router includes at least three bidirectional energy balance commutation chains.

The power router further includes K converter units, K is an integer greater than or equal to 1 and less than or equal to M. The input end of the converter unit is connected to the positive and negative electrodes of the first DC capacitor, and the output end is connected to the load or power supply. There is an isolation unit between the input end and the output end of the converter unit. As shown in Figure 6, K=2, including 2 converter units.

Among them, the electric energy router of the present invention is composed of the following several ways.

(1) As shown in Figure 7A, the electrical energy router has a DC positive pole and a DC negative pole, wherein the electrical energy router includes six bidirectional energy balance converter chains to form a three-phase upper bridge arm and a three-phase lower bridge arm; The first power port of the upper bridge arm converter chain is connected to the DC positive pole, and the second power port of the same phase upper bridge arm converter chain is connected to the first power port of the lower bridge arm converter chain; three-phase lower bridge arm commutation The second power port of the chain is connected with the DC negative pole; the second power port of the three-phase upper bridge arm converter chain is led out as the AC terminal of the electric energy router.

Wherein, the first balanced ports of the three-phase upper-arm converter chain of the electric energy router are connected together, and the second balanced ports of the three-phase lower-arm converter chain of the electric energy router can be connected together.

Wherein, the second balance port of the upper bridge arm converter chain of the same phase and the first balance port of the lower bridge arm converter chain of the electric energy router may be connected together.

(2) As shown in Figure 7B, the electrical energy router includes three bidirectional energy balance converter chains. The first power ports of the three converter chains are connected together, the first balanced ports are connected together, and the second power The ports are respectively connected to the ABC three phases of the power grid; or the second power ports of the three converter chains are connected together, the second balance ports are connected together, and the first power ports are respectively connected to the ABC three phases of the power grid.

(3) As shown in Figure 7C, the electric energy router includes three bidirectional energy balance converter chains, the first power port of the converter chain and the second power port of the adjacent converter chain are connected to each other to form a closed loop; The first power port of the converter chain is respectively connected to the ABC three phases of the power grid, forming an angular connection.

Wherein, the first balance ports of the three converter chains and the second balance ports of the adjacent converter chains are connected to each other to form a closed loop.

The present invention also provides a control method of the two-way energy balance commutation chain, including:

Wherein, when the power unit fails, the second bypass switch in the power unit is closed, and the first bypass switch is closed at the same time.

The embodiments of the present application are described in detail above, and specific examples are used in this article to illustrate the principles and implementation manners of the present application. The descriptions of the above embodiments are only used to help understand the methods and core ideas of the present application. At the same time, the changes or deformations made by those skilled in the art based on the ideas of the application, the specific implementation and the scope of application of the application, are all within the protection scope of the application. In summary, the content of this specification should not be construed as a limitation on this application.

Claims

A bidirectional energy balance commutation chain is characterized in that it includes:

M power units, the M power units include two AC terminals, the AC terminals of adjacent power units are sequentially connected in series, the empty port of the head-end power unit is defined as the first power port, and the empty port of the tail-end power unit Leading out is defined as the second power port; the power unit includes a first DC capacitor and a power component connected in parallel, and M is an integer greater than or equal to 1;

N multi-port balance units, N is an integer greater than or equal to 1 and less than or equal to M;

The number P of the ports of the multi-port balance unit is 3 or 4;

When P=3, the multi-port balancing unit includes first, second, and third ports, and the third port is connected to the positive or negative pole of the first DC capacitor; when P=4, the multi-port balancing unit includes first, Two, three and four ports, the third port is connected to the positive pole of the DC capacitor, and the fourth port is connected to the negative pole of the DC capacitor; or the third port is connected to the negative pole of the DC capacitor, and the fourth port is connected to the positive pole of the DC capacitor;

The first port of the head end multi-port balance unit is defined as the first balance port, the second port is connected to the first port of the adjacent multi-port balance unit, and is connected in this way. The second port of the tail end multi-port balance unit The port lead is defined as the second balanced port.
The bidirectional energy balance commutation chain according to claim 1, wherein the multi-port balance unit in the bidirectional energy balance commutation chain is used to control the charging and discharging between the first DC capacitors of adjacent power units.
The two-way energy balance commutation chain according to claim 1, wherein the two-way energy balance commutation chain further comprises a first bypass switch, and the first bypass switch is connected in parallel to the first multi-port balancing unit. Between the port and the second port.
The bidirectional energy balance commutation chain according to claim 1, wherein P=4, the multi-port balance unit includes first, second, third, and fourth switch units, and one end of the first and second switch units is connected to The first and second ports are connected; the other ends of the first and second switch units are connected to the third port after being connected; one end of the third and fourth switch units is respectively connected to the first and second ports, and the other end is connected to the fourth port.
The two-way energy balance commutation chain according to claim 1, wherein P=3, the multi-port balance unit includes a first and a second switch unit, and one end of the first and second switch unit is connected to the first and second switch units respectively. Port connection; the first switch unit is connected to the other end of the second switch unit and then connected to the third port.
The bidirectional energy balance commutation chain according to claim 1, wherein P=4, the multi-port balance unit includes a first, a second, and a third switch unit, and one end of the first and second switch units is connected to the first switch unit. , Two-port connection; the first switch unit is connected to the other end of the second switch unit and then connected to the third port; one end of the third switch unit is connected to the first port or the second port, and the other end is connected to the fourth port.
The two-way energy balance commutation chain according to claim 1, wherein P=3, the multi-port balance unit includes a first and a second switch unit, and one end of the first and second switch unit is connected to the first and second switch units respectively. Port connection; the other end of the first switch unit is connected to the second port, and the other end of the second switch unit is connected to the third port.
The bidirectional energy balance commutation chain according to claim 1, wherein P=4, the multi-port balance unit includes a first, a second, and a third switch unit, and one end of the first and second switch units is connected to the first switch unit. , Two-port connection; the other end of the first switch unit is connected to the second port, the other end of the second switch unit is connected to the third port, one end of the third switch unit is connected to the second port or the first port, and the other end is connected to the fourth port. Port connection.
The two-way energy balance converter chain according to claim 1, wherein P=3, the multi-port balance unit includes a first switch unit, and one end of the first switch unit is connected to the first port and the third port at the same time. Port, the other end is connected to the second port.
The two-way energy-balanced commutation chain according to claims 4-9, wherein each switch unit in the two-way energy-balanced commutation chain includes a power semiconductor device or a mechanical switch.
The two-way energy-balanced commutation chain according to claim 10, characterized in that, each switch unit in the two-way energy-balanced commutation chain further comprises a current-limiting resistor, an inductor, a fuse, or any combination of three devices. The current limiting unit is connected in series with the power semiconductor device or the mechanical switch in the switch unit.
The two-way energy-balanced commutation chain according to claim 1, wherein the two-way energy-balanced commutation chain further comprises an isolating switch group, and the isolating switch group is connected in series with the third and fourth ports and the first DC capacitor positive , Between the negative poles; when P=3, the switch group includes one switch, and when P=4, the switch group includes at least one switch.
The two-way energy balance converter chain according to claim 1, wherein the power components in the power unit are composed of two fully-controlled power semiconductor devices in the form of half-bridge connection, or are composed of four fully-controlled power semiconductor devices. The semiconductor device is formed in the form of a full bridge connection, or is formed by a fully-controlled power semiconductor device in parallel with a buffer circuit, and the buffer circuit is formed by a diode and a capacitor in series.
The two-way energy-balanced converter chain according to claim 1, wherein the converter chain further comprises at least one protection unit, and the protection unit comprises a protection resistor and a protection switch, which are connected in series at any position in the converter chain Or connected in parallel to both ends of the first DC capacitor.
The two-way energy balance commutation chain according to claim 14, wherein the protection unit comprises a first protection switch and a first protection resistor, and the first protection switch and the first protection resistor are connected in parallel; wherein the first protection switch is Two IGBTs with anti-parallel diodes connected in series in the opposite direction are connected in series with a mechanical switch.
The two-way energy balance commutation chain according to claim 15, wherein the protection unit further comprises a second protection switch, a second protection resistor, and a second DC capacitor; the second DC capacitor and the second protection switch and After the second protection resistor is connected in series, it is connected in parallel with the first protection resistor and the first protection switch.
The bidirectional energy balance commutation chain according to claim 14, wherein the protection unit includes a second protection switch and a second protection resistor, and after the second protection switch and the second protection resistor are connected in series, they are connected in parallel to the first protection switch. Both ends of a DC capacitor.
The bidirectional energy balance converter chain according to claim 1, wherein the power unit further comprises: a second bypass switch connected in parallel to the AC end of the power unit.
The two-way energy balance converter chain according to claim 1, further comprising:

At least one DC port is connected to the anode and the cathode of the first DC capacitor; the DC port is used to connect to the DC side of the converter unit or lead out as a backup port.
An electric energy router, characterized in that, the electric energy router includes at least three bidirectional energy balance commutation chains according to claims 1-15.
The power router according to claim 20, wherein the power router further comprises K converter units, K is an integer greater than or equal to 1 and less than or equal to M, and the input end of the converter unit is connected to the first DC capacitor The positive pole and the negative pole of the converter unit are connected to the load or the power source at the output end, and there is an isolation unit between the input end and the output end of the converter unit.
The electrical energy router according to claim 20, wherein the electrical energy router has a DC positive pole and a DC negative pole, wherein the electrical energy router includes six bidirectional energy balance converter chains to form a three-phase upper bridge arm and a three-phase lower arm. Bridge arm; the first power port of the three-phase upper-arm converter chain is connected to the DC positive pole, and the second power port of the same-phase upper-arm converter chain is connected to the first power port of the lower-arm converter chain; three-phase The second power port of the lower bridge arm converter chain is connected to the DC negative pole; the second power port of the three-phase upper bridge arm converter chain is led out as the AC terminal of the electric energy router.
The electrical energy router according to claim 22, wherein the first balance ports of the three-phase upper arm converter chain of the electrical energy router are connected together, and the three-phase lower arm converter chain of the electrical energy router is connected together. The second balanced ports are connected together.
The electrical energy router according to claim 22, wherein the second balance port of the in-phase upper bridge arm converter chain of the electrical energy router is connected to the first balance port of the lower bridge arm converter chain.
The electrical energy router according to claim 20, wherein the electrical energy router comprises three bidirectional energy-balanced converter chains, the first power ports of the three converter chains are connected together, and the second power ports are respectively connected The ABC three phases of the power grid; or the second power ports of the three converter chains are connected together, and the first power ports are respectively connected to the ABC three phases of the power grid.
The electrical energy router according to claim 25, wherein the first power ports of the three converter chains are connected together, and the first balance ports are connected together, and the second power ports are respectively connected to the ABC three-phase of the power grid. Or the second power ports of the three converter chains are connected together, and the second balanced ports are connected together, and the first power ports are respectively connected to the ABC three phases of the power grid.
The electrical energy router according to claim 20, wherein the electrical energy router comprises three bidirectional energy-balanced converter chains, the first power port of the converter chain and the second power port of the adjacent converter chain are connected to each other, A closed loop is formed; the first power port or the second power port of the three converter chains are respectively connected to the ABC three-phase of the power grid, forming an angular connection.
The electrical energy router according to claim 27, wherein the first balance ports of the three converter chains and the second balance ports of the adjacent converter chains are connected to each other to form a closed loop.
A control method based on the two-way energy balance commutation chain of claims 1-19, characterized in that it comprises:

When the DC voltage of the power units in the bidirectional energy balance converter chain is uneven, by controlling the switching units in the multi-port balance unit, a circuit for charging and discharging the first DC capacitor between adjacent power units is established to maintain the DC of the power unit. Voltage balance

When the DC capacitor voltage of any power unit is higher than the DC capacitor voltage of the adjacent power unit, the DC capacitor with a higher voltage is discharged to the DC capacitor of the adjacent power unit through the multi-port balance unit connected to the power unit.
The control method according to claim 29, wherein when the power unit fails, the second bypass switch in the power unit is closed, and the first bypass switch is closed at the same time.