A multi-port dc conversion topology

Abstract

The present application relates to a kind of multi-port direct current conversion topological structures, the topological structure includes: multiple phase circuits;Each phase circuit includes: high voltage port, high voltage port switch, multiple low voltage ports, multiple low voltage port switches, first voltage conversion circuit and second voltage conversion circuit;The end of the high voltage port of multiple phase circuits is connected with each other, and all low voltage ports are connected with each other;The other end of each low voltage port is connected with the low voltage end of first voltage conversion circuit and the low voltage end of second voltage conversion circuit by corresponding low voltage port switch, the other end of high voltage port is connected with the high voltage end of first voltage conversion circuit and the high voltage end of second voltage conversion circuit by high voltage port switch, and the low voltage end of first voltage conversion circuit is also connected with the low voltage end of second voltage conversion circuit;First voltage conversion circuit and second voltage conversion circuit are used to carry out voltage grade conversion, and can meet the demand of GW level power collection and delivery.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically to a multi-port DC-DC converter topology. Background Technology

[0002] The development and construction of large-scale distributed onshore new energy and deep-sea wind power have progressed rapidly, marking a new stage of large-scale, high-quality development for renewable energy in my country. New energy resources are widely distributed but have low individual capacity. Traditional point-to-point grid connection is inefficient, costly, and reliant on thermal power or AC synchronous grids. In recent years, with the continuous expansion of new energy bases, there is an urgent need to break through the limitations of traditional aggregation methods to achieve GW-level power aggregation and transmission. However, current aggregation methods cannot meet the demands of GW-level power aggregation. Summary of the Invention

[0003] To address the problem that existing collection methods cannot meet the requirements of GW-level power collection, this invention provides a multi-port DC-DC converter topology, which includes: multiple phase circuits; each phase circuit includes: a high-voltage port, a high-voltage port switch, multiple low-voltage ports, multiple low-voltage port switches, a first voltage conversion circuit, and a second voltage conversion circuit. One end of the high-voltage port of the multiple phase circuits is connected to each other; all the low-voltage ports of the multiple phase circuits are connected to each other. In each phase circuit, the other end of each low-voltage port is connected to the low-voltage terminal of the first voltage conversion circuit and the low-voltage terminal of the second voltage conversion circuit through a corresponding low-voltage port switch. The other end of the high-voltage port is connected to the high-voltage terminal of the first voltage conversion circuit and the high-voltage terminal of the second voltage conversion circuit through the high-voltage port switch. The low-voltage terminal of the first voltage conversion circuit is also connected to the low-voltage terminal of the second voltage conversion circuit. The first voltage conversion circuit and the second voltage conversion circuit are used to perform voltage level conversion.

[0004] Optionally, the first voltage conversion circuit and the second voltage conversion circuit have symmetrical structures.

[0005] Optionally, the high-voltage port includes a high-voltage positive port and a high-voltage negative port, and the high-voltage port switch includes a high-voltage positive port switch and a high-voltage negative port switch; the low-voltage port includes a low-voltage positive port and a low-voltage negative port, and the low-voltage port switch includes a low-voltage positive port switch and a low-voltage negative port switch. The first voltage conversion circuit includes: a plurality of first voltage conversion units; one end of the plurality of first voltage conversion units connected in series is connected to a corresponding low-voltage positive port through a plurality of low-voltage positive port switches, and is connected to a corresponding low-voltage negative port through a plurality of low-voltage negative port switches; the other end of the plurality of first voltage conversion units connected in series is connected to the high-voltage positive port through the high-voltage positive port switch. The second voltage conversion circuit includes: a plurality of second voltage conversion units, the second voltage conversion units being structurally symmetrical with the first voltage conversion unit; one end of the plurality of second voltage conversion units connected in series is connected to a corresponding low-voltage positive port through a plurality of low-voltage positive port switches, and is connected to a corresponding low-voltage negative port through a plurality of low-voltage negative port switches; the other end of the plurality of second voltage conversion units connected in series is connected to a high-voltage negative port through a high-voltage negative port switch.

[0006] Optionally, both the first voltage conversion unit and the second voltage conversion unit include: a first on / off control branch, a second on / off control branch, an energy storage module, and a third on / off control branch; In the first voltage conversion unit, one end of the first on / off control branch is connected to one end of the energy storage module, and the other end of the first on / off control branch is connected to a corresponding low-voltage positive port through a plurality of low-voltage positive port switches, and is also connected to one end of the third on / off control branch; the other end of the third on / off control branch is connected to the other end of the energy storage module, and the other end of the energy storage module is also connected to one end of the second on / off control branch; the other end of the second on / off control branch is connected to a corresponding low-voltage negative port through a plurality of low-voltage negative port switches; and one end of the energy storage module is also connected to the high-voltage positive port through a high-voltage positive port switch; In the second voltage conversion unit, one end of the first on / off control branch is connected to one end of the energy storage module, and the other end of the first on / off control branch is connected to a corresponding low-voltage negative port through a plurality of low-voltage negative port switches, and is also connected to one end of the third on / off control branch; the other end of the third on / off control branch is connected to the other end of the energy storage module, and the other end of the energy storage module is also connected to one end of the second on / off control branch; the other end of the second on / off control branch is connected to a corresponding low-voltage positive port through a plurality of low-voltage positive port switches; and one end of the energy storage module is also connected to the high-voltage negative port through a high-voltage negative port switch, and each on / off control branch includes at least a switching device.

[0007] Optionally, the first on / off control branch includes: a plurality of first switching devices connected in series, and a static voltage equalization circuit and a dynamic voltage equalization circuit connected in parallel across the two ends of each first switching device; the two ends of the plurality of first switching devices connected in series are the two ends of the first on / off control branch; the first switching device includes a diode or a thyristor with an anti-parallel diode. The second on / off control branch includes: a plurality of second switching devices connected in series, and a static voltage equalization circuit and a dynamic voltage equalization circuit connected in parallel across each second switching device; the two ends of the plurality of second switching devices connected in series are the two ends of the second on / off control branch; the second switching device includes a thyristor or a thyristor with an anti-parallel diode; The third on / off control branch includes: multiple third switching devices connected in series, and a static voltage equalization circuit and a dynamic voltage equalization circuit connected in parallel across each of the third switching devices; the two ends of the multiple third switching devices connected in series are the two ends of the third on / off control branch; the third switching device includes a thyristor or a thyristor with an anti-parallel diode.

[0008] Optionally, the energy storage module includes: an inductor and a plurality of energy storage units connected in series, wherein the two ends of the plurality of energy storage units connected in series with the inductor serve as one end and the other end of the energy storage module, respectively. Each of the energy storage units includes at least one half-bridge circuit and a DC capacitor, wherein the half-bridge circuit and the DC capacitor are connected in parallel.

[0009] Optionally, the energy storage unit includes a half-bridge circuit, which is connected in parallel with the DC capacitor. The midpoint of one arm of the half-bridge circuit is connected to one end of the first on / off control branch, and the negative terminal of the arm is connected to the inductor. In the case of multiple half-bridge circuits, the DC capacitor is connected in parallel among the multiple half-bridge circuits, and the midpoint of one arm of one half-bridge circuit is connected to one end of the first on / off control branch, while the midpoint of the arm of another half-bridge circuit is connected to the inductor.

[0010] Optionally, the energy storage unit includes multiple half-bridge circuits, and the energy storage unit further includes a first diode, a second diode, and a third switching device. The multiple half-bridge circuits include a first half-bridge circuit and a second half-bridge circuit, and the DC capacitor includes a first DC capacitor and a second DC capacitor. The first half-bridge circuit, the second half-bridge circuit, the first DC capacitor, the second DC capacitor, and the third switching device are connected in parallel; the anode of the first diode is connected to the positive terminal of the first half-bridge circuit, and the cathode of the first diode is connected to the positive terminal of the second half-bridge circuit; the anode of the second diode is connected to the negative terminal of the first half-bridge circuit, and the cathode of the second diode is connected to the negative terminal of the second half-bridge circuit. The midpoint of the bridge arm of the first half-bridge circuit is connected to one end of the first on / off control branch, and the midpoint of the bridge arm of the second half-bridge circuit is connected to the inductor.

[0011] Optionally, each of the energy storage units further includes: a battery; the battery is connected in parallel with the DC capacitor; The type of battery includes at least one of the following: lithium battery, lead-acid battery, vanadium redox flow battery, sodium-sulfur battery, electrochemical capacitor, or superconducting magnetic energy storage device.

[0012] Optionally, each of the half-bridge circuits includes: a plurality of fourth switching devices connected in series; Each of the fourth switching devices includes at least one of the following: an IGBT with an anti-parallel diode, an IGCT with an anti-parallel diode, or a silicon carbide MOSFET with an anti-parallel diode.

[0013] Optionally, each of the low-voltage port switches includes a plurality of thyristors connected in series, or a plurality of IGCTs connected in series; the high-voltage port switch includes a plurality of thyristors connected in series, or a plurality of IGCTs connected in series. Alternatively, each of the low-voltage port switches includes a plurality of thyristors with anti-parallel diodes connected in series, or a plurality of IGCTs with anti-parallel diodes connected in series; the high-voltage port switch includes a plurality of thyristors with anti-parallel diodes connected in series, or a plurality of IGCTs with anti-parallel diodes connected in series.

[0014] Optionally, each of the phase circuits further includes: a positive common port, a negative common port, and a fourth on / off control branch; Multiple low-voltage positive ports converge to the positive common port through corresponding low-voltage positive port switches, and the other ends of the first on / off control branches in multiple first voltage conversion units and the other ends of the second on / off control branches in multiple second voltage conversion units also converge to the positive common port; Multiple low-voltage negative ports converge to the negative common port through corresponding low-voltage negative port switches, and the other ends of the second on / off control branches in multiple first voltage conversion units and the other ends of the first on / off control branches in multiple second voltage conversion units also converge to the negative common port; The fourth on / off control branch is connected between the positive common port and the negative common port.

[0015] Optionally, the fourth on / off control branch includes: a plurality of fifth switching devices connected in series; one end of the plurality of fifth switching devices connected in series is connected to the positive common port, and the other end of the plurality of fifth switching devices connected in series is connected to the negative common port; The fifth switching device includes multiple diodes, multiple thyristors, or multiple IGCTs connected in series.

[0016] Optionally, the static voltage equalization circuit includes a static voltage equalization resistor; The dynamic voltage equalization circuit includes a dynamic voltage equalization capacitor and a dynamic voltage equalization resistor connected in series; one end of the dynamic voltage equalization resistor and the dynamic voltage equalization capacitor connected in series is connected to the cathode of the diode, and the other end is connected to the anode of the diode; or, one end of the dynamic voltage equalization resistor and the dynamic voltage equalization capacitor connected in series is connected to the anode of the diode in the thyristor with anti-parallel diode, and the other end is connected to the cathode of the diode in the thyristor with anti-parallel diode.

[0017] On the other hand, embodiments of the present invention also propose a multi-port DC converter system, including the multi-port DC converter topology described above, multiple new energy sources, and a DC bus; The multiple new energy sources are connected to multiple low-voltage ports of the multi-port DC converter topology, and the DC bus is connected to the high-voltage port of the multi-port DC converter topology.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention relates to a multi-port DC-DC converter topology, which includes: multiple phase circuits; each phase circuit includes: a high-voltage port, a high-voltage port switch, multiple low-voltage ports, multiple low-voltage port switches, a first voltage conversion circuit, and a second voltage conversion circuit; one end of the high-voltage ports of the multiple phase circuits is interconnected; all low-voltage ports of the multiple phase circuits are interconnected; in each phase circuit, the other end of each low-voltage port is connected to the low-voltage terminal of the first voltage conversion circuit and the low-voltage terminal of the second voltage conversion circuit through a corresponding low-voltage port switch, and the other end of the high-voltage port is connected to the high-voltage terminal of the first voltage conversion circuit and the high-voltage terminal of the second voltage conversion circuit through a high-voltage port switch; the low-voltage terminal of the first voltage conversion circuit is also connected to the low-voltage terminal of the second voltage conversion circuit; the first voltage conversion circuit and the second voltage conversion circuit are used to perform voltage level conversion. The multi-port DC converter topology in this invention provides multiple low-voltage ports that can realize DC aggregation of multiple new energy sources. Furthermore, through the connection method between the first voltage conversion circuit, the second voltage conversion circuit and the high and low voltage ports in each phase circuit, it can be ensured that the first voltage conversion circuit and the second voltage conversion circuit can withstand both the DC current of the low-voltage port and the DC voltage of the high-voltage port when performing voltage level conversion, thereby meeting the requirements of GW-level power aggregation and transmission. Attached Figure Description

[0019] Figure 1 A schematic diagram of a multi-port DC-DC converter topology provided by the present invention; Figure 2 A schematic diagram of a single-phase circuit in a multi-port DC-DC converter topology provided by the present invention; Figure 3 A schematic diagram of a single-phase circuit in a multi-port DC-DC converter topology provided by the present invention; Figure 4 This is a schematic diagram of a first voltage conversion unit topology provided by the present invention; Figure 5 This is a schematic diagram of a second voltage conversion unit topology provided by the present invention; Figure 6 A schematic diagram of the on / off control branch including a unidirectional switching device provided by the present invention; Figure 7 This is a schematic diagram of the on / off control branch containing a bidirectional switching device provided by the present invention. Figure 8 A schematic diagram of a multi-port DC-DC converter topology provided by the present invention; Figure 9 A schematic diagram of the energy storage unit topology provided by the present invention; Figure 10 This is a schematic diagram of a multi-port DC-DC converter system provided by the present invention. Detailed Implementation

[0020] Example 1: To meet the growing demand for the collection and transmission of new energy resources, such as the collection and transmission demand at the GW level, this invention provides a multi-port DC-DC converter topology, such as... Figure 1 and Figure 2 As shown, the topology may include: multiple phase circuits; each phase circuit includes: a high-voltage port, a high-voltage port switch, multiple low-voltage ports, multiple low-voltage port switches, a first voltage conversion circuit, and a second voltage conversion circuit. One end of the high-voltage port of multiple phase circuits is connected to each other; all the low-voltage ports of multiple phase circuits are connected to each other. In each phase circuit, the other end of each low-voltage port is connected to the low-voltage terminal of the first voltage conversion circuit and the low-voltage terminal of the second voltage conversion circuit through a corresponding low-voltage port switch. The other end of the high-voltage port is connected to the high-voltage terminal of the first voltage conversion circuit and the high-voltage terminal of the second voltage conversion circuit through a high-voltage port switch. The low-voltage terminal of the first voltage conversion circuit is also connected to the low-voltage terminal of the second voltage conversion circuit. The first voltage conversion circuit and the second voltage conversion circuit are used to perform voltage level conversion.

[0021] In this embodiment of the invention, the multi-port DC converter topology provides multiple low-voltage ports that can realize DC aggregation of multiple new energy sources. Furthermore, through the connection method between the first voltage conversion circuit, the second voltage conversion circuit and the high and low voltage ports in each phase circuit, it can be ensured that the first voltage conversion circuit and the second voltage conversion circuit can withstand both the DC current of the low-voltage port and the DC voltage of the high-voltage port when performing voltage level conversion, thereby meeting the requirements of GW-level power aggregation and transmission.

[0022] In this topology, the multiple phase circuits have the same structure but different phases. The identical structure ensures that each phase circuit can withstand the same voltage and current stress during voltage level changes, thereby achieving current sharing and uniform power distribution. This avoids the failure of the entire DC commutation process due to the failure of a single phase circuit. The different phases allow for control of the operating timing of each phase circuit, enabling the current ripples to cancel each other out on the time axis. This results in a (near) ideal smooth DC at the output port, improving the port current quality. Furthermore, since this control method can naturally achieve ripple cancellation, there is no need to use the large-volume, high-cost DC inductors used in traditional topologies to filter ripples, thus reducing the size and cost of the topology.

[0023] After one end of the high-voltage port of multiple phase circuits is interconnected, it can be used to connect to the external DC bus to jointly bear the high-voltage output power on the DC bus side. For example... Figure 1As shown, the high-voltage port includes a high-voltage positive port and a high-voltage negative port, and the high-voltage positive port of multiple phase circuits. V H One end of the + terminal can be connected to the positive terminal of the DC bus, and the high-voltage negative terminal of multiple phase circuits. V H One end of each phase can be connected to the negative terminal of the DC bus, thus forming a multi-phase high-voltage output structure to jointly bear the total output power of the GW pole.

[0024] The interconnection of all low-voltage ports in multiple phase circuits enables flexible access and power decoupling of multiple new energy sources. Figure 1 Taking a circuit containing M phase circuits, where each phase circuit has multiple low-voltage ports including k low-voltage positive ports and k low-voltage negative ports, as an example, all low-voltage positive ports in the multiple phase circuits are interconnected within the topology, such as the low-voltage positive ports in the M phase circuits. V L1 +Interconnected V L2 +Interconnected, ... V Lk + Interconnected, all low-voltage negative ports are interconnected within the topology, such as the low-voltage positive ports in an M-phase circuit. V L1 Interconnected V L2 Interconnected, ... V Lk The interconnected topology, although each phase circuit contains k low-voltage positive and negative ports within the topology, still has k low-voltage positive and negative ports on the external side. This simplifies the access method for multiple new energy sources, and the power of any new energy source can be dynamically allocated to any phase circuit within the topology for processing. It also improves the redundancy and power regulation flexibility of the system.

[0025] Specifically, Figure 1 The topology of the medium-voltage DC converter equipment includes M Individual phase circuits: Phase circuit 1#, ..., Phase circuit M #. Each phase circuit includes k One low-voltage positive / negative port: V L1 + / V L1 … V Lk + / V Lk and a high-voltage positive / negative port:V H + / V H All low-voltage ports of all phase circuits are interconnected, and high-voltage ports are interconnected. The voltages of the multiple low-voltage ports are ± V L1 、…、± V Lk The voltage levels can be unequal, and there is no electrical isolation between the low-voltage and high-voltage ports. For example, the low-voltage DC port voltage levels are ±100kV and ±200kV, while the high-voltage DC port voltage levels are ±500kV, ±525kV, and ±800kV; or the low-voltage DC port voltage levels are ±20kV, ±30kV, and ±50kV, while the high-voltage DC port voltage levels are ±100kV and ±200kV.

[0026] In this topology, the interconnection of the low-voltage terminals of the first voltage conversion circuit and the second voltage conversion circuit can include at least two connection methods: First, the low-voltage terminals of the two voltage conversion circuits are interconnected, with the first and second voltage conversion circuits connected in series to form a full-bridge or half-bridge output structure; second, as... Figure 2 As shown, the low-voltage terminals of the two voltage conversion circuits are interconnected through an on / off control branch. This branch can be used to control the operating mode between the two voltage conversion circuits (such as switching between series and parallel modes), adapting to different input voltage ranges. The specific connection structure and control process for the second connection method are detailed in the fourth on / off control branch section, and will not be elaborated upon here.

[0027] Each low-voltage port switch includes multiple thyristors connected in series, or multiple IGCTs connected in series; the high-voltage port switch includes multiple thyristors connected in series, or multiple IGCTs connected in series. Alternatively, each low-voltage port switch includes a plurality of thyristors with anti-parallel diodes connected in series, or a plurality of IGCTs with anti-parallel diodes connected in series; the high-voltage port switch includes a plurality of thyristors with anti-parallel diodes connected in series, or a plurality of IGCTs with anti-parallel diodes connected in series.

[0028] In one implementation, the first voltage conversion circuit and the second voltage conversion circuit are structurally symmetrical. Structural symmetry means that the topologies of the first and second voltage conversion circuits are identical, but their connection polarities are opposite, forming a symmetrical positive and negative configuration. For example... Figure 3The single-phase circuit includes a first voltage conversion circuit and a second voltage conversion circuit. The high-voltage side of the first voltage conversion circuit is connected to the high-voltage positive port, and the low-voltage side is connected to the low-voltage positive port. The high-voltage side of the second voltage conversion circuit is connected to the high-voltage negative port, and the low-voltage side is connected to the low-voltage negative port. Their polarities are opposite, and both the first and second voltage conversion circuits are series-stacked structures composed of N cascaded voltage conversion units. Their structures are identical. It can be understood that the first and second voltage conversion circuits, except... Figure 3 The voltage conversion unit series structure shown can also be configured as a hybrid cascade or a structure containing redundant modules according to actual scenario requirements to further improve fault tolerance.

[0029] In this implementation, the symmetrical structure of the first and second voltage conversion circuits means they bear equal voltage stress but have opposite polarities. The DC bus voltage can be evenly distributed between the two circuits, achieving voltage balance. Furthermore, because their low-voltage ends are shared and their high-voltage ends are symmetrical, the common-mode voltage during the DC commutation process can be balanced, reducing the insulation requirements to ground. Additionally, due to their symmetry, combined with specific control methods, harmonic components during the conversion process can be canceled, helping to reduce voltage ripple and improve power quality. Moreover, this symmetrical structure, with bipolar inputs on both the low-voltage and high-voltage sides, also provides bidirectional energy flow capability.

[0030] For example, the high-voltage port includes a high-voltage positive port and a high-voltage negative port. Correspondingly, the high-voltage port switch includes a high-voltage positive port switch and a high-voltage negative port switch. The high-voltage positive port switch is connected in series with the positive terminal of the high-voltage side circuit, and the high-voltage negative port switch is connected in series with the negative terminal of the high-voltage side circuit. The high-voltage positive port switch and the high-voltage negative port switch can control the on / off state of the high-voltage side and isolate faults.

[0031] For example, the low-voltage port includes a low-voltage positive port and a low-voltage negative port. Correspondingly, the low-voltage port switch includes a low-voltage positive port switch and a low-voltage negative port switch. Each low-voltage positive port switch is connected in series with the positive terminal of the low-voltage side circuit where the low-voltage positive port is located, and each low-voltage negative port switch is connected in series with the negative terminal of the low-voltage side circuit where the low-voltage negative port is located. By controlling the on / off state of different low-voltage positive port switches and different low-voltage negative port switches, different (or different types) of new energy sources can be connected. To further enable flexible multi-port access and multi-voltage level conversion, combined with Figure 3In one example, the first voltage conversion circuit includes: multiple first voltage conversion units; one end of the multiple first voltage conversion units connected in series is connected to a corresponding low-voltage positive port through multiple low-voltage positive port switches, and is also connected to a corresponding low-voltage negative port through multiple low-voltage negative port switches; the other end of the multiple first voltage conversion units connected in series is connected to a high-voltage positive port through a high-voltage positive port switch. In this example, one end of the multiple first voltage conversion units connected in series serves as the low-voltage terminal of the first voltage conversion circuit, which can be connected in parallel to any one or more low-voltage ports, and can correspondingly connect to any one or more new energy sources; while the other end of the multiple first voltage conversion units connected in series serves as the high-voltage terminal of the first voltage conversion circuit, used to connect to the DC bus through the high-voltage port.

[0032] The second voltage conversion circuit includes: multiple second voltage conversion units, which are structurally symmetrical with the first voltage conversion unit; one end of the multiple second voltage conversion units connected in series is connected to a corresponding low-voltage positive port through multiple low-voltage positive port switches, and to a corresponding low-voltage negative port through multiple low-voltage negative port switches; the other end of the multiple second voltage conversion units connected in series is connected to a high-voltage negative port through a high-voltage negative port switch. In this example, one end of the multiple second voltage conversion units connected in series serves as the low-voltage terminal of the second voltage conversion circuit, which can be connected in parallel to any one or more low-voltage ports, and can correspondingly connect to any one or more new energy sources; the other end of the multiple second voltage conversion units connected in series serves as the high-voltage terminal of the second voltage conversion circuit, used to connect to the DC bus through the high-voltage port.

[0033] In this example, both the first and second voltage conversion circuits possess the capability for both unidirectional and bidirectional energy flow, enabling multi-voltage level conversion. By increasing or decreasing the number of the first and second voltage conversion units, the boost ratio capability of this topology can be improved or reduced.

[0034] In one implementation, both the first voltage conversion unit and the second voltage conversion unit include: a first on / off control branch, a second on / off control branch, an energy storage module, and a third on / off control branch; through the cooperation of the three on / off control branches and the energy storage module, flexible voltage conversion and polarity control can be achieved.

[0035] For example, see Figure 4In the first voltage conversion unit, one end of the first on / off control branch is connected to one end of the energy storage module. The other end of the first on / off control branch is connected to a corresponding low-voltage positive port via multiple low-voltage positive port switches, and also connected to one end of the third on / off control branch. The other end of the third on / off control branch is connected to the other end of the energy storage module, and the other end of the energy storage module is also connected to one end of the second on / off control branch. The other end of the second on / off control branch is connected to a corresponding low-voltage negative port via multiple low-voltage negative port switches. Furthermore, one end of the energy storage module is connected to a high-voltage positive port via a high-voltage positive port switch. Figure 4 In this circuit, the first on / off control branch is located between the positive terminal of the input port and the positive terminal of the output port, the second on / off control branch is located between the negative terminal of the input port and the negative terminal of the output port, and the first and second on / off control branches can be used to control the parallel mode of the first voltage conversion unit, and the third on / off control branch is located between the positive terminal of the input port and the negative terminal of the output port to control the series mode of the first voltage conversion unit.

[0036] For example, see Figure 5 In the second voltage conversion unit, one end of the first on / off control branch is connected to one end of the energy storage module. The other end of the first on / off control branch is connected to a corresponding low-voltage negative port via multiple low-voltage negative port switches, and also connected to one end of the third on / off control branch. The other end of the third on / off control branch is connected to the other end of the energy storage module, and the other end of the energy storage module is also connected to one end of the second on / off control branch. The other end of the second on / off control branch is connected to a corresponding low-voltage positive port via multiple low-voltage positive port switches. Furthermore, one end of the energy storage module is connected to a high-voltage negative port via a high-voltage negative port switch. Each on / off control branch includes at least a switching device. Figure 5 In this circuit, the first on / off control branch is located between the negative terminal of the input port and the negative terminal of the output port, the second on / off control branch is located between the positive terminal of the input port and the positive terminal of the output port, and the first and second on / off control branches can be used to control the parallel mode of the second voltage conversion unit. The third on / off control branch is located between the negative terminal of the input port and the positive terminal of the output port and is used to control the series mode of the second voltage conversion unit.

[0037] In this example, the low-voltage terminal of the first voltage conversion unit is connected with positive input and negative output, while the low-voltage terminal of the second voltage conversion unit is connected with negative input and positive output. Since their polarities are opposite, they can form a symmetrical voltage output when cascaded. Furthermore, through the coordinated control of the first, second, and third on / off control branches, the voltage of the energy storage module can be superimposed or bypassed, making it more suitable for multi-voltage level scenarios.

[0038] Specifically, by coordinating the control of each on / off control branch, all first and second voltage conversion units are in series mode, capable of withstanding the DC voltage at the high-voltage output port, thus reducing the voltage stress on each voltage conversion unit. If, through coordinating control, all first and second voltage conversion units are in parallel mode, they can withstand the DC current at the low-voltage input port, reducing the current stress on each voltage conversion unit. Therefore, in this embodiment of the invention, each voltage conversion unit can be selected from low-voltage and low-current-stress devices to reduce the overall cost.

[0039] In one implementation, taking an example where both the first voltage conversion unit and the second voltage conversion unit are N, the total number of them, 2N, is equal to the voltage at the high-voltage output port. V H Divide by k The minimum voltage of each low-voltage input port min( V L1 , V L1 ,…, V Lk And taking the nearest even number, its essence is to divide the high voltage demand by the minimum low voltage input and multiply by a safety factor to obtain the total number of voltage conversion units. In this implementation, using k The minimum voltage of each low-voltage input port is used as a reference to calculate the total number of voltage conversion units required. This ensures that even when a certain new energy source reaches its lowest voltage, the topology can still guarantee the required high-voltage output, avoiding shutdown. Taking the nearest even number provides the freedom of voltage adjustment, preventing the entire topology from operating in extreme conditions, lacking adjustment space, and being unable to cope with sudden load changes or voltage fluctuations.

[0040] To improve the high-voltage stress withstand capability and reliability of high-voltage ports, one implementation includes a first on / off control branch comprising: multiple first switching devices connected in series, and a static voltage equalization circuit and a dynamic voltage equalization circuit connected in parallel across each first switching device; the two ends of the series connection of the multiple first switching devices constitute the two ends of the first on / off control branch. A second on / off control branch comprises: multiple second switching devices connected in series, and a static voltage equalization circuit and a dynamic voltage equalization circuit connected in parallel across each second switching device; the two ends of the series connection of the multiple second switching devices constitute the two ends of the second on / off control branch. A third on / off control branch comprises: multiple third switching devices connected in series, and a static voltage equalization circuit and a dynamic voltage equalization circuit connected in parallel across each third switching device; the two ends of the series connection of the multiple third switching devices constitute the two ends of the third on / off control branch. In this implementation, the use of multiple switching devices connected in series in each on / off control branch can withstand the high-voltage stress of the high-voltage port, which is beneficial for adapting to the high-voltage environment required for GW power collection and transmission. Furthermore, the parallel connection of static and dynamic voltage equalization circuits across each switching device can prevent overvoltage damage caused by voltage unevenness during the on / off transition of the switching devices.

[0041] Each switching device can be a unidirectional switching device or a bidirectional switching device. Unidirectional switching devices are suitable for unidirectional energy flow scenarios, while bidirectional switching devices are suitable for bidirectional energy flow scenarios.

[0042] Unidirectional switching devices include, but are not limited to, one of the following: diodes, thyristors, IGCTs (Integrated Gate-Commutated Thyristors), IGBTs (Insulated Gate Bipolar Transistors), and silicon carbide MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors). The unidirectional switching device includes diode on / off control branches such as... Figure 6 The structure of the diode series valve is shown, and the one-way switching device included is a thyristor on / off control branch, as shown in the figure. Figure 6 The structure of the thyristor series valve is shown, and the one-way switching device included is the on / off control branch of the IGCT. Figure 6 The structure of the IGCT series valve is shown, and the one-way switching device included is the IGBT on / off control branch, as shown in the figure. Figure 6 The structure of the IGBT series valve is shown, and the unidirectional switching device included is a silicon carbide MOSFET. The on / off control branch is as follows: Figure 6The structure of the silicon carbide MOSFET series valve is shown. Diode series valves and thyristor series valves are relatively inexpensive, and their selection can reduce the overall cost. IGCT series valves, on the other hand, have fault current blocking capabilities. Therefore, the specific type of unidirectional switching device to be selected can be chosen based on the actual needs of the current scenario, and no restrictions are imposed here.

[0043] Bidirectional switching devices include, but are not limited to, one of the following: a thyristor with an anti-parallel diode, an IGCT with an anti-parallel diode, an IGBT with an anti-parallel diode, a silicon carbide MOSFET with an anti-parallel diode, a bidirectional thyristor, a bidirectional anti-parallel IGCT, a bidirectional anti-parallel IGBT, and a bidirectional anti-parallel silicon carbide MOSFET. The bidirectional switching device includes the on / off control branch of a thyristor with an anti-parallel diode, such as... Figure 7 The structure of the thyristor series valve with anti-parallel diode is shown, and the bidirectional switching device included is the on / off control branch of the IGCT with anti-parallel diode, as shown in the figure. Figure 7 The structure of the IGCT series valve with anti-parallel diode is shown. The bidirectional switching device included is the on / off control branch of the IGBT with anti-parallel diode, as shown below. Figure 7 The structure of the IGBT series valve with an anti-parallel diode is shown. The bidirectional switching device included is a silicon carbide MOSFET with an anti-parallel diode, and the on / off control branch is as follows: Figure 7 The structure of the silicon carbide MOSFET series valve with an anti-parallel diode is shown, and the included bidirectional switching device is the on / off control branch of the bidirectional thyristor, as shown in the figure. Figure 7 The structure of the bidirectional thyristor series valve is shown, and the bidirectional switching device included is the on / off control branch of the bidirectional anti-parallel IGCT, as shown in the figure. Figure 7 The structure of the bidirectional anti-parallel IGCT series valve is shown, and the bidirectional switching device included is the on / off control branch of the bidirectional anti-parallel IGBT, as shown in the figure. Figure 7 The structure of the bidirectional anti-parallel IGBT series valve is shown, and the bidirectional switching device included is a bidirectional anti-parallel silicon carbide MOSFET on / off control branch, as shown below. Figure 7 The structure of the bidirectional anti-parallel silicon carbide MOSFET series valve is shown. The specific type of bidirectional switching device selected can be chosen based on the actual needs of the current scenario; no restrictions are imposed here.

[0044] A static voltage equalization circuit includes a static voltage equalization resistor. When the switching devices are off, this circuit uses voltage division to evenly distribute the voltage across the series-connected switching devices, eliminating static voltage unevenness caused by differences in leakage current between the switching devices. A dynamic voltage equalization circuit includes a dynamic voltage equalization capacitor and a dynamic voltage equalization resistor connected in series. At the moment of switching device operation, the dynamic voltage equalization circuit uses the charging and discharging characteristics of the dynamic voltage equalization capacitor to suppress the rate of voltage change and absorb voltage spikes during the switching process, thereby achieving a uniform dynamic voltage distribution and protecting the switching devices from damage caused by transient overvoltages.

[0045] For example, in a unidirectional energy flow scenario, the first switching device includes a diode, the second switching device includes a thyristor, and the third switching device includes a thyristor or a thyristor with an anti-parallel diode, such as... Figure 6 As shown, one end of the dynamic voltage equalizing resistor and the dynamic voltage equalizing capacitor, connected in series, is connected to the cathode of the diode, and the other end is connected to the anode of the diode. In another example, in a bidirectional energy flow scenario, the first switching device includes a thyristor with an anti-parallel diode, the second switching device includes a thyristor with an anti-parallel diode, and the third switching device includes a thyristor with an anti-parallel diode, as shown... Figure 7 As shown, one end of the dynamic voltage equalizing resistor and the dynamic voltage equalizing capacitor connected in series is connected to the anode of the diode in the thyristor with anti-parallel diode, and the other end is connected to the cathode of the diode in the thyristor with anti-parallel diode.

[0046] In one implementation, the energy storage module includes: an inductor and multiple energy storage units connected in series, wherein the two ends of the series connection between the multiple energy storage units and the inductor serve as one end and the other end of the energy storage module, respectively. Figure 8 As shown. Inductors can serve as filters and energy storage devices, such as common-mode inductors or differential-mode inductors. By connecting multiple energy storage units in series, higher voltage levels and more flexible energy management can be achieved.

[0047] Each energy storage unit includes at least one half-bridge circuit and a DC capacitor connected in parallel. By increasing or decreasing the number of half-bridge circuits and DC capacitors, the voltage level or power handling capability of the entire energy storage module can be easily improved. Furthermore, the modular design of the energy storage unit can reduce maintenance difficulty and cost. The DC capacitor can also play a filtering role in voltage balancing, improving the reliability of the energy storage unit.

[0048] In one example, such as Figure 9 As shown in topology 1, the energy storage unit includes a half-bridge circuit, a half-bridge circuit and a DC capacitor connected in parallel, the midpoint of the bridge arm of the half-bridge circuit is connected to one end of the first on / off control branch, and the negative terminal of the bridge arm is connected to an inductor. This topology is simple and can automatically balance the DC bias by utilizing the characteristics of the half-bridge circuit.

[0049] In yet another example, such as Figure 9 As shown in Topologies 2 and 3, when the energy storage unit includes multiple half-bridge circuits, DC capacitors are connected in parallel between the multiple half-bridge circuits, and the midpoint of the bridge arm of one half-bridge circuit is connected to one end of the first on / off control branch, while the midpoint of the bridge arm of another half-bridge circuit is connected to an inductor. In this topology, the multiple half-bridge circuits can share the voltage, improve the withstand voltage level, and reduce the harmonic distortion of the current waveform. Referring to Topology 3, when the energy storage unit includes multiple half-bridge circuits, the energy storage unit may further include: a first diode, a second diode, and a third switching device. The multiple half-bridge circuits include a first half-bridge circuit and a second half-bridge circuit. The DC capacitors include a first DC capacitor and a second DC capacitor. The first half-bridge circuit, the second half-bridge circuit, the first DC capacitor, the second DC capacitor, and the third switching device are connected in parallel. The anode of the first diode is connected to the positive terminal of the first half-bridge circuit, and the cathode of the first diode is connected to the positive terminal of the second half-bridge circuit. The anode of the second diode is connected to the negative terminal of the first half-bridge circuit, and the cathode of the second diode is connected to the negative terminal of the second half-bridge circuit. The midpoint of the bridge arm of the first half-bridge circuit is connected to one end of the first on / off control branch, and the midpoint of the bridge arm of the second half-bridge circuit is connected to an inductor. In this topology, the first diode and the second diode are connected in series between the two half-bridge circuits. This prevents current from flowing back from the second half-bridge circuit to the first half-bridge circuit, ensuring that the first half-bridge circuit is not directly affected by the high power fluctuations in the subsequent stage. The third switching device can be turned on when either of the first half-bridge circuits fails, bypassing the faulty half-bridge circuit, preventing the fault from escalating, and continuing to operate at a lower power level.

[0050] In one possible implementation, each energy storage unit further includes: a battery; the battery is connected in parallel with a DC capacitor; the battery can be one or more types of batteries, possessing energy storage capabilities, and can achieve uninterrupted energy delivery even in the event of a failure at the new energy port. The battery type includes at least one of the following: lithium battery, lead-acid battery, vanadium redox flow battery, sodium-sulfur battery, electrochemical capacitor, or superconducting magnetic energy storage device.

[0051] In one implementation, each half-bridge circuit includes multiple fourth switching devices connected in series. The series connection of multiple fourth switching devices improves the voltage withstand capability of the half-bridge circuit. The fourth switching devices may have reverse conduction capability to accommodate the freewheeling requirements in the half-bridge circuit. For example, each fourth switching device may include at least one of the following: an IGBT with an anti-parallel diode, an IGCT with an anti-parallel diode, or a silicon carbide MOSFET with an anti-parallel diode. Optionally, to avoid uneven instantaneous voltage distribution caused by differences in device parameters and drive signal delays, the half-bridge circuit may also include a voltage equalization circuit connected in parallel across each fourth switching device, such as a static voltage equalization circuit and / or a dynamic voltage equalization circuit. For example, the energy storage unit may preferably be selected from topology 1, and the fourth switching device may preferably be an IGBT with an anti-parallel diode.

[0052] In one implementation, each phase circuit further includes: a positive common port (e.g., Figure 8 In V L +), negative common port (e.g.) Figure 8 In V L The system comprises a first on / off control branch and a fourth on / off control branch. Multiple low-voltage positive ports converge to a common positive port via corresponding low-voltage positive port switches. The other ends of the first on / off control branches in multiple first voltage conversion units and the second on / off control branches in multiple second voltage conversion units also converge to the common positive port. Multiple low-voltage negative ports converge to a common negative port via corresponding low-voltage negative port switches. The other ends of the second on / off control branches in multiple first voltage conversion units and the first on / off control branches in multiple second voltage conversion units also converge to the common negative port. A fourth on / off control branch connects the common positive port and the common negative port. This implementation enables bidirectional energy flow between multiple low-voltage ports and high-voltage ports and provides short-circuit protection.

[0053] For example, the fourth on / off control branch includes: multiple fifth switching devices connected in series (such as...) Figure 8 In S s1+j and S s1 j One end of the series connection of multiple fifth switching devices is connected to the positive common port, and the other end of the series connection of multiple fifth switching devices is connected to the negative common port.

[0054] The fifth switching device includes multiple diodes, multiple thyristors, or multiple IGCTs connected in series.

[0055] by Figure 8 The phase circuit shownj Taking # as an example, a specific topology for each phase circuit in this topology is explained, where j takes values ​​in the range [1, M], and M is the number of phase circuits. Phase circuit j #Include k A low-voltage positive port switch S p1+j , S p2+j … S pk+j ( j = 1,2,…, M ), k A low-voltage negative terminal switch S p1 j , S p2 j … S pk j One high-voltage positive port switch S s2+j One high-voltage negative port switch S s2 j 2 fifth switching devices S s1+j , S s1 j (Together they constitute the fourth on / off control branch). N First voltage transformation units: a1, a2, ..., a N (Together they constitute the first voltage conversion circuit). N Two second voltage conversion units: b1, b2, ..., b N (Together forming the second voltage conversion circuit). Low-voltage positive port V L1 +、 V L2 +、…、 V Lk + Through their respective series-connected low-voltage positive port switches S p1+j , S p2+j … S pk+j Connect to the positive common port V L +, Low-voltage negative port V L1 ,V L2 … V Lk Through their respective series-connected low-voltage negative terminal switches S p1 j , S p2 j … S pk j Connect to the negative common port V L Positive common port V L + and negative common port V L A fifth switching device is connected between them. S s1+j , S s1 j Positive common port V L + and negative common port V L The input ports of the first voltage conversion unit a1 and the second voltage conversion unit b1 are connected in parallel. The first voltage conversion unit a... i ( i = 1,2,…, N The output port of ) is connected to the first voltage conversion unit a( i +1) input port. Second voltage conversion unit b i ( i = 1,2,…, N The output port of ) is connected to the second voltage conversion unit b. i +1) input port, wherein the first on / off control branch in the first voltage conversion unit a1 is S a11j The second on / off control branch in the first voltage conversion unit a1 is S a12j The third on / off control branch in the first voltage conversion unit a1 is S a13j The first on / off control branch in the first voltage conversion unit aN is: S aN1j The second on / off control branch in the first voltage conversion unit aN isS aN2j The third on / off control branch in the first voltage conversion unit aN is S aN3j The first on / off control branch in the second voltage conversion unit b1 is... S b11j The second on / off control branch in the second voltage conversion unit b1 is S b12j The third on / off control branch in the second voltage conversion unit b1 is S b13j The first on / off control branch in the second voltage conversion unit bN is... S bN1j The second on / off control branch in the second voltage conversion unit bN is S bN2j The third on / off control branch in the second voltage conversion unit bN is S bN3j The first voltage conversion unit and the second voltage conversion unit also include an energy storage module, which consists of an inductor connected in series and multiple energy storage units.

[0056] In one implementation, the number of phase circuits M and the number of low-voltage input ports k satisfy the following relationship: M = k +2. This structure allows for full-power or derating operation even in the event of a single independent fault, providing greater fault tolerance. Furthermore, when the topology is operating normally, the phase circuits in this structure can share voltage stress and provide an additional boost ratio. In addition, a larger number of phase circuits can make the output voltage and current waveforms smoother. In this implementation, the operating timing angles of every two phase circuits (such as phase circuit j# and phase circuit j+1#) differ by 360° / (k+2). This timing misalignment allows each phase to "take turns operating" in parallel, naturally canceling out current ripples.

[0057] The multi-port DC-DC converter topology shown in this embodiment of the invention can be applied to both unidirectional and multidirectional energy flow scenarios.

[0058] In unidirectional energy flow scenarios, multi-port DC converter topologies are primarily used to aggregate and centrally transmit distributed renewable energy from various power plants. The low-voltage ports of a multi-port DC converter topology can connect to multiple renewable energy collection buses, while the high-voltage ports can connect to renewable energy transmission buses, providing a high step-up ratio voltage transformation capability. Specifically, this involves aggregating multiple medium / high-voltage DC renewable energy sources, converting their energy through multi-port DC converter equipment, and then stepping up the voltage to a higher level for transmission as medium / high-voltage DC. This effectively avoids the stability bottlenecks inherent in AC systems and reduces line transmission losses.

[0059] Combination Figure 8In this unidirectional energy flow scenario, the selection can include: a low-voltage positive port switch. S p1+j , S p2+j … S pk+j ( j = 1,2,…, M and low-voltage negative port switch S p1 j , S p2 j … S pk j The structure can be either a thyristor series valve or an IGCT series valve. Using an IGCT series valve allows the low-voltage positive and negative port switches to have fault current blocking capability. High-voltage positive port switch... S s2+j and high voltage negative terminal switch S s2 j Choose either a thyristor series valve or an IGCT series valve. Using an IGCT series valve allows the high-voltage positive and negative port switches to have fault current blocking capability. Fifth switching device. S s1+j , S s1 j A diode series valve is selected to reduce cost and control complexity. In the first voltage conversion unit, the first on / off control branch... S ai1j ( i = 1,2,…, N ; j = 1,2,…, M A diode series valve is selected; the second on / off control branch... S ai2j Select a thyristor series valve; third on / off control branch S ai3j A thyristor-connected valve is selected. In the second voltage conversion unit, the first on / off control branch... S bi1j ( i = 1,2,…, N ; j = 1,2,…, M A diode series valve is selected; the second on / off control branch... S bi2jSelect a thyristor series valve; third on / off control branch S bi3j A thyristor series valve is selected. The energy storage unit in the first voltage conversion unit and the second voltage conversion unit adopts topology 1, and the switching device is an IGBT with anti-parallel diode.

[0060] In bidirectional energy flow scenarios, multi-port DC converter topologies are mainly used to realize energy flow from the low-voltage side to the high-voltage side and from the high-voltage side to the low-voltage side.

[0061] When realizing energy flow from the low-voltage side to the high-voltage side, the operation of this topology includes: parallel charging of the low-voltage port to the first voltage conversion circuit and the second voltage conversion circuit, and series discharging of the first voltage conversion circuit and the second voltage conversion circuit to the high-voltage port. For example, during parallel charging, the first on / off control branch of each first voltage conversion unit (e.g., ...) controls the on / off state of the first on / off control branch. S ai1j … S aN1j ) and the second on / off control branch is on (e.g. S ai2j … S aN2j ), the first on / off control branch of each second voltage conversion unit and (such as S bi1j … S bN1j Second on / off control branch (such as...) S bi2j … S bN2j The circuit is turned on, causing the first voltage conversion circuit and the second voltage conversion circuit to form a parallel mode, and controlling the low-voltage port switch (e.g., the low-voltage port of the input energy, hereinafter referred to as the charging low-voltage port) corresponding to the low-voltage port switch. S p1+j / S p1 j ,or S p2+j / S p2 j ,…,or S pk+j / S pk j (or a combination of multiple low-voltage port switches) is turned on, and the low-voltage port charges the first voltage conversion circuit and the second voltage conversion circuit in parallel; all other switches and branches are turned off, including the third on / off control branch of each first voltage conversion unit (such as...).S ai3j … S aN3j ) turn off, the third on / off control branch of each second voltage conversion unit (such as S bi3j … S bN3j ) Turn-off, fourth on / off control branch (such as the fifth switching device) S s1+j , S s1 j ) Shutdown, high-voltage port switch (such as S s2+j , S s2 j The low-voltage port switch corresponding to the low-voltage port where no energy is input is turned off (e.g., if the charging low-voltage port is...). S p1+j / S p1 j ,but S p2+j / S p2 j … S pk+j / S pk j (Shutdown). Another example is the third on / off control branch controlling each first voltage conversion unit during series discharge (e.g., ...). S ai3j … S aN3j ) is turned on, and the third on / off control branch of each second voltage conversion unit (such as S bi3j … S bN3j The circuit is turned on, causing the first voltage conversion circuit and the second voltage conversion voltage to form a series mode, and controlling the fourth on / off control branch (such as the fifth switching device). S s1+j , S s1 j ) Conducting, high-voltage port switch (such as S s2+j , S s2 jWhen the voltage is turned on, the first voltage conversion circuit and the second voltage conversion circuit discharge in series at the high-voltage port; all other switches and branches are turned off, controlling the first on / off control branch of each first voltage conversion unit (such as...). S ai1j … S aN1j ) and the second on / off control branch is on (e.g. S ai2j … S aN2j ) turn off, the first on / off control branch of each second voltage conversion unit and (such as S bi1j … S bN1j Second on / off control branch (such as...) S bi2j … S bN2j ) Turn off, and switch the low-voltage port corresponding to all low-voltage ports (such as S p1+j / S p1 j , S p2+j / S p2 j … S pk+j / S pk j ( ) Shutdown. During the energy flow from the high-voltage side to the low-voltage side, the high-voltage port is charged in series with the first voltage conversion circuit and the second voltage conversion circuit, and the first voltage conversion circuit and the second voltage conversion circuit are discharged in parallel with the low-voltage port.

[0062] When realizing energy flow from the high-voltage side to the low-voltage side, the operation of this topology includes: the high-voltage port performing series charging to the first voltage conversion circuit and the second voltage conversion circuit, and the first voltage conversion circuit and the second voltage conversion circuit performing parallel discharging to the low-voltage port respectively. For example, during series charging, the third on / off control branch of each first voltage conversion unit (such as...) controls the on / off state of... S ai3j … S aN3j ) is turned on, and the third on / off control branch of each second voltage conversion unit (such as S bi3j … S bN3jThe circuit is turned on, causing the first voltage conversion circuit and the second voltage conversion voltage to form a series mode, and controlling the fourth on / off control branch (such as the fifth switching device). S s1+j , S s1 j ) Conducting, high-voltage port switch (such as S s2+j , S s2 j The circuit is turned on, and the high-voltage port charges the first and second voltage conversion circuits in series; all other switches and branches are turned off, controlling the first on / off control branch of each first voltage conversion unit (such as...). S ai1j … S aN1j ) and the second on / off control branch is on (e.g. S ai2j … S aN2j ) turn off, the first on / off control branch of each second voltage conversion unit and (such as S bi1j … S bN1j Second on / off control branch (such as...) S bi2j … S bN2j ) Turn off, and switch the low-voltage port corresponding to all low-voltage ports (such as S p1+j / S p1 j , S p2+j / S p2 j … S pk+j / S pk j ) Turn off. Another example is during parallel discharge, controlling the first on / off control branch of each first voltage conversion unit (e.g., S ai1j … S aN1j ) and the second on / off control branch is on (e.g. S ai2j … S aN2j), the first on / off control branch of each second voltage conversion unit and (such as S bi1j … S bN1j Second on / off control branch (such as...) S bi2j … S bN2j The circuit is turned on, causing the first voltage conversion circuit and the second voltage conversion circuit to form a parallel mode, and controlling the low-voltage port switch corresponding to the low-voltage port of the output energy (hereinafter referred to as the discharge low-voltage port) (such as...). S p1+j / S p1 j ,or S p2+j / S p2 j ,…,or S pk+j / S pk j (or a combination of multiple low-voltage port switches) is turned on, and the first voltage conversion circuit and the second voltage conversion circuit discharge the low-voltage port in parallel; all other switches and branches are turned off, including the third on / off control branch of each first voltage conversion unit (such as...). S ai3j … S aN3j ) turn off, the third on / off control branch of each second voltage conversion unit (such as S bi3j … S bN3j ) Turn-off, fourth on / off control branch (such as the fifth switching device) S s1+j , S s1 j ) Shutdown, high-voltage port switch (such as S s2+j , S s2 j The low-voltage port switch corresponding to the low-voltage port that has no input energy is turned off (e.g., if the discharge low-voltage port is...). S p1+j / S p1 j ,but Sp2+j / S p2 j … S pk+j / S pk j (Shut down).

[0063] Combination Figure 8 The selection for this bidirectional energy flow scenario can include: a low-voltage positive port switch. S p1+j , S p2+j … S pk+j ( j = 1,2,…, M and low-voltage negative port switch S p1 j , S p2 j … S pk j Choose either a thyristor series valve with an anti-parallel diode or an IGCT series valve with an anti-parallel diode. Using an IGCT series valve with an anti-parallel diode allows the low-voltage positive and negative port switches to have fault current blocking capability. High-voltage positive port switch... S s2+j and high voltage negative terminal switch S s2 j Choose either a thyristor series valve with an anti-parallel diode or an IGCT series valve with an anti-parallel diode. Using an IGCT series valve with an anti-parallel diode allows the high-voltage positive and negative port switches to have fault current blocking capability. Fifth Switching Device S s1+j , S s1 j A thyristor series valve with an anti-parallel diode is selected to reduce cost and control complexity. In the first voltage conversion unit, the first on / off control branch... S ai1j ( i = 1,2,…, N ; j = 1,2,…, M Select a thyristor series valve with anti-parallel diodes; second on / off control branchS ai2j Select a thyristor series valve with anti-parallel diodes; third on / off control branch S ai3j A thyristor series valve with an anti-parallel diode is selected. In the second voltage conversion unit, the first on / off control branch... S bi1j ( i = 1,2,…, N ; j = 1,2,…, M Select a thyristor series valve with anti-parallel diodes; second on / off control branch S bi2j Select a thyristor series valve with anti-parallel diodes; third on / off control branch S bi3j A thyristor series valve with an anti-parallel diode is selected.

[0064] As can be seen from the above embodiments, the multi-port DC converter topology proposed in this invention can reconstruct the charging and discharging circuit through dynamic control of switched capacitors, and therefore can be better applied to the scenario of new energy collection and transmission.

[0065] Furthermore, during charging and discharging, the rate of change of the charging or discharging current can be controlled based on the received charging or discharging current rate adjustment command to form a trapezoidal charging or discharging current. This control of the rate of change of the charging or discharging current can be achieved by controlling the conduction timing and duty cycle of multiple parallel charging or discharging circuits, or by combining the aforementioned timing of each phase circuit with a phase angle staggered by 360° / (k+2), or by controlling the conduction process of the high-voltage port switch in a series charging or discharging circuit. The trapezoidal charging or discharging current improves current quality and reduces switching stress and conduction losses.

[0066] Example 2: Based on the same inventive concept, the present invention also provides a multi-port DC-DC converter system, such as... Figure 10 As shown, it includes a multi-port DC converter topology, multiple new energy sources, and a DC bus; Multiple low-voltage ports of the multi-port DC converter topology are connected to multiple new energy sources, and the DC bus is connected to the high-voltage ports of the multi-port DC converter topology.

[0067] The multi-port DC-DC converter topology is shown in the above embodiment and will not be described again here.

[0068] Understandably, with multiple renewable energy sources connected to the low-voltage port and the DC bus connected to the high-voltage port, the multi-port DC converter topology can boost the medium / high voltage of multiple renewable energy sources to higher voltage levels and send them to the DC bus, achieving unidirectional energy flow. Alternatively, it can convert the medium / high voltage on the DC bus side and output it to multiple renewable energy sources, achieving bidirectional energy flow.

[0069] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A multi-port DC-DC converter topology, characterized in that, The topology includes: multiple phase circuits; one end of the high-voltage ports of the multiple phase circuits are interconnected; all low-voltage ports of the multiple phase circuits are interconnected; in each phase circuit, the other end of each low-voltage port is connected to the low-voltage terminal of the first voltage conversion circuit and the low-voltage terminal of the second voltage conversion circuit through a corresponding low-voltage port switch; the other end of the high-voltage port is connected to the high-voltage terminal of the first voltage conversion circuit and the high-voltage terminal of the second voltage conversion circuit through a high-voltage port switch; the low-voltage terminal of the first voltage conversion circuit is also connected to the low-voltage terminal of the second voltage conversion circuit; the high-voltage port includes a high-voltage positive port and a high-voltage negative port, and the high-voltage port switch includes a high-voltage positive port switch and a high-voltage negative port switch; the low-voltage port includes a low-voltage positive port and a low-voltage negative port, and the low-voltage port switch includes a low-voltage positive port switch and a low-voltage negative port switch; the first voltage conversion circuit includes multiple first voltage conversion units, and the second voltage conversion circuit includes multiple second voltage conversion units; the first voltage conversion circuit and the second voltage conversion circuit are used for voltage level conversion. In the first voltage conversion unit, one end of the first on / off control branch is connected to one end of the energy storage module. The other end of the first on / off control branch is connected to a corresponding low-voltage positive port via multiple low-voltage positive port switches, and is also connected to one end of the third on / off control branch. The other end of the energy storage module is connected to the other end of the third on / off control branch and one end of the second on / off control branch. The other end of the second on / off control branch is connected to a corresponding low-voltage negative port via multiple low-voltage negative port switches. One end of the energy storage module is also connected to a high-voltage positive port via a high-voltage positive port switch. In the second voltage conversion unit, one end of the first on / off control branch is connected to one end of the energy storage module. The other end of the first on / off control branch is connected to a corresponding low-voltage negative port via multiple low-voltage negative port switches, and is also connected to one end of the third on / off control branch. The other end of the energy storage module is connected to the other end of the third on / off control branch. The other end of the circuit is connected to one end of the second on / off control branch; the other end of the second on / off control branch is connected to the corresponding low-voltage positive port through multiple low-voltage positive port switches; and one end of the energy storage module is also connected to the high-voltage negative port through a high-voltage negative port switch; in the first on / off control branch, the two ends of multiple first switching devices connected in series are the two ends of the first on / off control branch; in the second on / off control branch, the two ends of multiple second switching devices connected in series are the two ends of the second on / off control branch; in the third on / off control branch, the two ends of multiple third switching devices connected in series are the two ends of the third on / off control branch; each first, second, and third switching device has a static voltage equalization circuit and a dynamic voltage equalization circuit connected in parallel at both ends; the first switching device includes a diode or a thyristor with an anti-parallel diode, and the second and third switching devices include thyristors or thyristors with an anti-parallel diode; In each phase circuit, the positive common port is connected to one end of the series connection of multiple fifth switching devices in the fourth on / off control branch, and the negative common port is connected to the other end of the series connection of multiple fifth switching devices.

2. The topology according to claim 1, characterized in that, The first voltage conversion circuit and the second voltage conversion circuit have symmetrical structures.

3. The topology according to claim 1 or 2, characterized in that, One end of the series connection of multiple first voltage conversion units is connected to the corresponding low-voltage positive port through multiple low-voltage positive port switches, and is also connected to the corresponding low-voltage negative port through multiple low-voltage negative port switches. The other end of the series connection of multiple first voltage conversion units is connected to the high-voltage positive port through the high-voltage positive port switch. The second voltage conversion unit is symmetrical to the first voltage conversion unit in structure; one end of the multiple second voltage conversion units connected in series is connected to the corresponding low-voltage positive port through multiple low-voltage positive port switches, and is connected to the corresponding low-voltage negative port through multiple low-voltage negative port switches; the other end of the multiple second voltage conversion units connected in series is connected to the high-voltage negative port through the high-voltage negative port switch.

4. The topology according to claim 1, characterized in that, The energy storage module includes: an inductor and multiple energy storage units connected in series, wherein the two ends of the multiple energy storage units connected in series with the inductor serve as one end and the other end of the energy storage module, respectively. Each of the energy storage units includes at least one half-bridge circuit and a DC capacitor, wherein the half-bridge circuit and the DC capacitor are connected in parallel.

5. The topology according to claim 4, characterized in that, The energy storage unit includes a half-bridge circuit, which is connected in parallel with the DC capacitor. The midpoint of one arm of the half-bridge circuit is connected to one end of the first on / off control branch, and the negative terminal of the arm is connected to the inductor. In the case of multiple half-bridge circuits, the DC capacitor is connected in parallel among the multiple half-bridge circuits, and the midpoint of one arm of one half-bridge circuit is connected to one end of the first on / off control branch, while the midpoint of the arm of another half-bridge circuit is connected to the inductor.

6. The topology according to claim 4, characterized in that, The energy storage unit includes multiple half-bridge circuits, and the energy storage unit further includes a first diode, a second diode, and a third switching device. The multiple half-bridge circuits include a first half-bridge circuit and a second half-bridge circuit. The DC capacitor includes a first DC capacitor and a second DC capacitor. The first half-bridge circuit, the second half-bridge circuit, the first DC capacitor, the second DC capacitor, and the third switching device are connected in parallel; the anode of the first diode is connected to the positive terminal of the first half-bridge circuit, and the cathode of the first diode is connected to the positive terminal of the second half-bridge circuit; the anode of the second diode is connected to the negative terminal of the first half-bridge circuit, and the cathode of the second diode is connected to the negative terminal of the second half-bridge circuit. The midpoint of the bridge arm of the first half-bridge circuit is connected to one end of the first on / off control branch, and the midpoint of the bridge arm of the second half-bridge circuit is connected to the inductor.

7. The topology according to claim 4, characterized in that, Each of the energy storage units further includes: a battery; the battery is connected in parallel with the DC capacitor; The type of battery includes at least one of the following: lithium battery, lead-acid battery, vanadium redox flow battery, sodium-sulfur battery, electrochemical capacitor, or superconducting magnetic energy storage device.

8. The topology according to claim 4, characterized in that, Each of the half-bridge circuits includes: a plurality of fourth switching devices connected in series; Each of the fourth switching devices includes at least one of the following: an IGBT with an anti-parallel diode, an IGCT with an anti-parallel diode, or a silicon carbide MOSFET with an anti-parallel diode.

9. The topology according to claim 1, characterized in that, Each of the low-voltage port switches includes a plurality of thyristors connected in series, or a plurality of IGCTs connected in series; the high-voltage port switch includes a plurality of thyristors connected in series, or a plurality of IGCTs connected in series. Alternatively, each of the low-voltage port switches includes a plurality of thyristors with anti-parallel diodes connected in series, or a plurality of IGCTs with anti-parallel diodes connected in series; the high-voltage port switch includes a plurality of thyristors with anti-parallel diodes connected in series, or a plurality of IGCTs with anti-parallel diodes connected in series.

10. The topology according to claim 1, characterized in that, Multiple low-voltage positive ports converge to the positive common port through corresponding low-voltage positive port switches, and the other ends of the first on / off control branches in multiple first voltage conversion units and the other ends of the second on / off control branches in multiple second voltage conversion units also converge to the positive common port; Multiple low-voltage negative ports converge to the negative common port through corresponding low-voltage negative port switches, and the other ends of the second on / off control branches in multiple first voltage conversion units and the other ends of the first on / off control branches in multiple second voltage conversion units also converge to the negative common port; The fourth on / off control branch is connected between the positive common port and the negative common port.

11. The topology according to claim 10, characterized in that, The fifth switching device includes multiple diodes, multiple thyristors, or multiple IGCTs connected in series.

12. The topology according to claim 1, characterized in that, The static voltage equalization circuit includes a static voltage equalization resistor; The dynamic voltage equalization circuit includes a dynamic voltage equalization capacitor and a dynamic voltage equalization resistor connected in series; one end of the dynamic voltage equalization resistor and the dynamic voltage equalization capacitor connected in series is connected to the cathode of the diode, and the other end is connected to the anode of the diode; or, one end of the dynamic voltage equalization resistor and the dynamic voltage equalization capacitor connected in series is connected to the anode of the diode in the thyristor with anti-parallel diode, and the other end is connected to the cathode of the diode in the thyristor with anti-parallel diode.

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