Hybrid topology through-type power supply system and design method

Abstract

A hybrid topology through-type power supply system and a design method. The system comprises three groups of cascade units which are connected to a three-phase power grid and a single-phase traction network. Each group of cascade units comprises a voltage regulation conversion module and a short-circuit path blocking module. The voltage regulation conversion module comprises a plurality of non-isolation units. The short-circuit path blocking module comprises a plurality of blocking units, and the blocking units comprise a plurality of no-load units and a plurality of isolation units. The short-circuit path blocking module is located on one side or two sides of the voltage regulation conversion module. The no-load units and the isolation units expand the phase angle range and improve the system stability by blocking a short-circuit path and enhancing the voltage balancing capability; and the non-isolation units are responsible for achieving specific functions such as voltage conversion or regulation.

Description

Hybrid Topology Through-Power Supply System and Design Methodology Technical Field

[0001] This invention relates to the field of through-power supply, and more particularly to hybrid topology through-power supply systems and design methods. Background Technology

[0002] The three-phase side of the traction power supply substation is connected to the high-voltage public power grid. The frequency, phase, and amplitude of the output voltage on the single-phase side of the substation are fully controllable. Interconnected substations can simultaneously provide power support to the load, thus completely eliminating the over-phase device and solving the power quality and over-phase problems of the traction power supply system. This is the ideal power supply method for future rail transit. However, the topology directly connected to the 110kV input has problems such as high cost and complex implementation.

[0003] To address this problem, existing technologies have proposed several feasible topologies, which can be mainly categorized into the following three types:

[0004] (1) The unit-cascaded multilevel topology based on the power frequency transformer is adopted as shown in Figure 1. The unit-cascaded multilevel topology containing the power frequency transformer converts the three-phase grid voltage into several independent AC low voltages that match the power units. The three-phase AC is converted to single-phase AC through rectification and inversion by the power units. The single-phase output side of the power units forms the traction network supply voltage through series connection, and directly supplies power to the traction network.

[0005] Although through-power supply devices using power frequency transformers are relatively mature in structure and control and widely used, the application of power frequency transformers simplifies the overall system topology, eliminates the need for multi-unit cascading on the input side, and allows direct connection to the traction network on the output side without the need for a step-up transformer. However, multi-winding transformers suffer from problems such as complex structure, high manufacturing cost, large footprint, and low efficiency.

[0006] (2) The unit-cascaded multilevel topology based on the medium- and high-frequency transformer is adopted as shown in Figure 2. This type of topology consists of an input rectifier, an isolated DC-DC converter containing a medium- and high-frequency transformer, and an output inverter. In Figure 2, ABC represents the three phases ABC, and N represents ground.

[0007] Although the cascaded unit structure containing medium- and high-frequency transformers eliminates the power frequency transformer through power electronic transformers (PET), improving device efficiency and saving space, this scheme, which replaces the power frequency transformer with PET, has advantages such as high efficiency and small size compared to structures that use power frequency transformers for device isolation. However, energy will be lost during DC-DC conversion, thus adding a DC-DC conversion, which also increases system losses and costs.

[0008] (3) The modular multilevel converter (MMC) topology shown in Figure 3 is adopted. Each unit contains a rectifier and an inverter, and power transmission and conversion are realized through modulation technology. In Figure 3, SM represents a sub-module of the modular multilevel converter topology (MMC).

[0009] The MMC converter is directly connected to 110kV, avoiding the use of multi-winding transformers and multiple medium- and high-frequency transformers, but it requires a large number of units and has a high cost. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hybrid topology through-power supply system and design method.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A first aspect of the present invention is a hybrid topology through-power supply system, comprising three cascaded units connecting a three-phase power grid and a single-phase traction network;

[0013] Each cascaded unit includes a voltage regulation and conversion module and a short-circuit path blocking module. The voltage regulation and conversion module includes several non-isolated units, and the short-circuit path blocking module includes several blocking units. The blocking units include several unloaded units and several isolated units. Each non-isolated unit and isolated unit includes an AC positive input terminal, an AC negative input terminal, an AC positive output terminal, and an AC negative output terminal. Each unloaded unit includes an AC positive input terminal, an AC negative input terminal, and an unused terminal.

[0014] The short-circuit path blocking module is located on one or both sides of the voltage regulation and conversion module, and the unloaded unit, isolation unit and non-isolation unit are arranged in sequence according to their positional relationship.

[0015] In a cascaded unit, the positive AC input terminal of the first unit is connected to one phase of the three-phase power grid, and the negative AC input terminal of the last unit is grounded. The negative AC input terminal of the preceding unit in a cascaded unit is connected to the positive AC input terminal of the following unit, and the negative AC output terminal of the preceding unit in a cascaded unit is connected to the positive AC output terminal of the following unit. Any positive AC output terminal is connected to the positive terminal of a single-phase traction network, and any negative AC output terminal is connected to the negative terminal of a single-phase traction network.

[0016] Furthermore, the short-circuit path blocking module is located in front of the voltage regulation and conversion module;

[0017] The positive AC input terminal of the short-circuit path blocking module is connected to one phase of the three-phase power grid; the negative AC input terminal of the short-circuit path blocking module is connected to the positive AC input terminal of the voltage regulation and conversion module; the negative AC input terminal of the voltage regulation and conversion module is grounded; the negative AC output terminal of the short-circuit path blocking module is connected to the positive AC output terminal of the voltage regulation and conversion module.

[0018] The positive AC input of the short-circuit path blocking module is the positive AC input of the first blocking unit, and the negative AC input of the short-circuit path blocking module is the negative AC input of the last blocking unit. The positive AC input of the voltage regulation and conversion module is the positive AC input of the first non-isolated unit, and the negative AC input of the voltage regulation and conversion module is the negative AC input of the last non-isolated unit. The negative AC output of the short-circuit path blocking module is the negative AC output of the last blocking unit, and the positive AC output of the voltage regulation and conversion module is the positive AC output of the first non-isolated unit.

[0019] Furthermore, the short-circuit path blocking module is located behind the voltage regulation and conversion module;

[0020] The positive AC input terminal of the voltage regulation and conversion module is connected to one phase of the three-phase power grid; the negative AC input terminal of the voltage regulation and conversion module is connected to the positive AC input terminal of the short-circuit path blocking module; the negative AC input terminal of the short-circuit path blocking module is grounded; the negative AC output terminal of the voltage regulation and conversion module is connected to the positive AC output terminal of the short-circuit path blocking module.

[0021] The positive AC input of the voltage regulator module is the positive AC input of the first non-isolated unit, and the negative AC input of the voltage regulator module is the negative AC input of the last non-isolated unit. The positive AC input of the short-circuit path blocking module is the positive AC input of the first blocking unit, and the negative AC input of the short-circuit path blocking module is the negative AC input of the last blocking unit. The negative AC output of the voltage regulator module is the negative AC output of the last non-isolated unit, and the positive AC output of the short-circuit path blocking module is the positive AC output of the first blocking unit.

[0022] Furthermore, the short-circuit path blocking module is located on both sides of the voltage regulation and conversion module, that is, the two ends of the voltage regulation and conversion module are respectively connected to the first short-circuit path blocking module and the second short-circuit path blocking module;

[0023] The positive AC input terminal of the first short-circuit path blocking module is connected to one phase of the three-phase power grid. The negative AC input terminal of the first short-circuit path blocking module is connected to the positive AC input terminal of the voltage regulation and conversion module. The negative AC input terminal of the voltage regulation and conversion module is connected to the positive AC input terminal of the second short-circuit path blocking module. The negative AC input terminal of the second short-circuit path blocking module is grounded. The negative AC output terminal of the first short-circuit path blocking module is connected to the positive AC output terminal of the voltage regulation and conversion module. The negative AC output terminal of the voltage regulation and conversion module is connected to the positive AC output terminal of the second short-circuit path blocking module.

[0024] The positive AC input terminal of the first short-circuit path blocking module is the positive AC input terminal of the first blocking unit in the first short-circuit path blocking module, and the negative AC input terminal of the first short-circuit path blocking module is the negative AC input terminal of the last blocking unit in the first short-circuit path blocking module. The positive AC input terminal of the voltage regulation and conversion module is the positive AC input terminal of the first non-isolated unit, and the negative AC input terminal of the voltage regulation and conversion module is the negative AC input terminal of the last non-isolated unit. The positive AC input terminal of the second short-circuit path blocking module is the positive AC input terminal of the first blocking unit in the second short-circuit path blocking module, and the negative AC input terminal of the second short-circuit path blocking module is the negative AC input terminal of the last blocking unit in the second short-circuit path blocking module.

[0025] The negative AC output of the first short-circuit path blocking module is the negative AC output of the last blocking unit in the first short-circuit path blocking module; the positive AC output of the voltage regulation and conversion module is the positive AC output of the first non-isolated unit; the negative AC output of the voltage regulation and conversion module is the negative AC output of the last non-isolated unit; and the positive AC output of the second short-circuit path blocking module is the positive AC output of the first blocking unit in the second short-circuit path blocking module.

[0026] Furthermore, the non-isolated unit includes a first rectifier, a first capacitor, and a first inverter;

[0027] The positive output terminal of the first rectifier is connected to the positive input terminal of the first inverter to form a first path, the negative output terminal of the first rectifier is connected to the negative input terminal of the first inverter to form a second path, and the first capacitor is connected between the first path and the second path.

[0028] The positive input terminal of the first rectifier serves as the positive AC input terminal of the non-isolated unit, the negative input terminal of the first rectifier serves as the negative AC input terminal of the non-isolated unit, the positive output terminal of the first inverter serves as the positive AC output terminal of the non-isolated unit, and the negative output terminal of the first inverter serves as the negative AC output terminal of the non-isolated unit.

[0029] Furthermore, the unloaded unit includes a second rectifier and a second capacitor;

[0030] The positive and negative output terminals of the second rectifier serve as the unused terminals of the unloaded unit, and the second capacitor is connected between the positive and negative output terminals of the second rectifier.

[0031] The positive input terminal of the second rectifier serves as the AC positive input terminal of the no-load unit, and the negative input terminal of the second rectifier serves as the AC negative input terminal of the no-load unit.

[0032] Furthermore, the isolation unit includes a third rectifier, a DC-DC converter, a second inverter, a third capacitor, and a fourth capacitor;

[0033] The positive output terminal of the third rectifier is connected to the positive input terminal of the DC-DC converter to form the third path. The negative output terminal of the third rectifier is connected to the negative input terminal of the DC-DC converter to form the fourth path. The positive output terminal of the DC-DC converter is connected to the positive input terminal of the second inverter to form the fifth path. The negative output terminal of the DC-DC converter is connected to the negative input terminal of the second inverter to form the sixth path. The third capacitor is connected between the third and fourth paths, and the fourth capacitor is connected between the fifth and sixth paths.

[0034] The positive input terminal of the third rectifier serves as the AC positive input terminal of the isolation unit, and the negative input terminal of the third rectifier serves as the AC negative input terminal of the isolation unit; the positive output terminal of the second inverter serves as the AC positive output terminal of the isolation unit, and the negative output terminal of the second inverter serves as the AC negative output terminal of the isolation unit.

[0035] A second aspect of the present invention provides a design method for a hybrid topology through-power supply system as described in the first aspect, comprising the following steps:

[0036] Determine the total number of non-isolated units, no-load units, and isolated units in the cascaded unit: Obtain the line voltage connected to the power grid and convert the line voltage into the phase voltage. At the same time, obtain the voltage withstand limit of the switching transistors of the input rectifiers in the non-isolated units, no-load units, and isolated units. Calculate the total number of non-isolated units, no-load units, and isolated units based on the ratio of the phase voltage to the voltage withstand limit of the switching transistors.

[0037] Determine the number of unloaded units: Based on the pressure equalization boundary setting, set the number of units in the first proportion of the total cascaded units to be in an unloaded state, i.e., the number of unloaded units;

[0038] Determine the number of isolation units: Based on the available vector to meet the traction power supply requirements, set the second proportion of units in the total cascaded number to block short-circuit paths, i.e., the number of unloaded units and isolation units. The number of isolation units is obtained by subtracting the first proportion of units from the second proportion of units.

[0039] Determine the number of non-isolated units: The number of non-isolated units is obtained by subtracting the total number of cascades from the total number of cascades by a second ratio.

[0040] Furthermore, the method further includes the following steps:

[0041] Determine the number of full-bridge and half-bridge units in the output inverter, including:

[0042] The input-output ratio is obtained based on the input phase voltage and the output voltage.

[0043] Assuming the input rectifier is a full-bridge structure, the number of equivalent full-bridge structures for the output inverter is obtained based on the total number of cascaded units and the input-output ratio.

[0044] The total number of output inverters is obtained by adding the number of isolated units and the number of non-isolated units. The number of equivalent full-bridge structures is obtained by configuring full-bridge and half-bridge structures based on the total number of output inverters. During the configuration process, a half-bridge unit is equivalent to 0.5 full-bridge units.

[0045] The beneficial effects of this invention are:

[0046] In an exemplary embodiment of the present invention, the cascaded unit is implemented using a hybrid topology of unloaded units, isolated units, and non-isolated units. When the unloaded units, isolated units, and non-isolated units are connected according to the above-described connection relationship, they together constitute a hybrid topology through-power supply system. In this system, the unloaded units and isolated units extend the phase shift angle range of the converter and improve system stability by blocking short-circuit paths and enhancing voltage equalization capabilities; while the non-isolated units are responsible for specific functions such as voltage conversion or adjustment. These three units cooperate to complete the overall function of the circuit system.

[0047] In yet another exemplary embodiment of the present invention, in order to meet the requirements of various traction loads on the converter vector boundary and ensure the stable operation of the system under various harsh environments, a design method for a hybrid topology through-power supply system is disclosed, mainly involving the calculation method of the number of unloaded units, isolated units, and non-isolated units. Attached Figure Description

[0048] Figure 1 is a schematic diagram of a three-phase to single-phase topology based on a power frequency transformer in the prior art;

[0049] Figure 2 is a schematic diagram of a three-phase to single-phase topology based on a medium- and high-frequency transformer in the prior art;

[0050] Figure 3 is a schematic diagram of a three-phase to single-phase topology based on a modular multilevel converter in the prior art;

[0051] Figure 4 is a schematic diagram of the hybrid topology through-power supply system provided in an exemplary embodiment of the present invention;

[0052] Figure 5 is a schematic diagram of the hybrid topology through-power supply system provided in another exemplary embodiment of the present invention;

[0053] Figure 6 is a schematic diagram of the hybrid topology through-power supply system provided in another exemplary embodiment of the present invention;

[0054] Figure 7 is a flowchart of a design method for a hybrid topology through-power supply system provided in an exemplary embodiment of the present invention;

[0055] Figure 8 is a flowchart of a design method for a hybrid topology through-power supply system provided in another exemplary embodiment of the present invention. Detailed Implementation

[0056] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0060] Referring to Figures 4 to 6, which illustrate schematic diagrams of a hybrid topology through-type power supply system provided in an exemplary embodiment of the present invention, the system includes three cascaded units connecting a three-phase power grid and a single-phase traction network; characterized in that:

[0061] Each cascaded unit includes a voltage regulation and conversion module and a short-circuit path blocking module. The voltage regulation and conversion module includes several non-isolated units, and the short-circuit path blocking module includes several blocking units. The blocking units include several unloaded units and several isolated units. Each non-isolated unit and isolated unit includes an AC positive input terminal, an AC negative input terminal, an AC positive output terminal, and an AC negative output terminal. Each unloaded unit includes an AC positive input terminal, an AC negative input terminal, and an unused terminal.

[0062] The short-circuit path blocking module is located on one or both sides of the voltage regulation and conversion module, and the unloaded unit, isolation unit and non-isolation unit are arranged in sequence according to their positional relationship.

[0063] In a cascaded unit, the positive AC input terminal of the first unit is connected to one phase of the three-phase power grid, and the negative AC input terminal of the last unit is grounded. The negative AC input terminal of the preceding unit in a cascaded unit is connected to the positive AC input terminal of the following unit, and the negative AC output terminal of the preceding unit in a cascaded unit is connected to the positive AC output terminal of the following unit. Any positive AC output terminal is connected to the positive terminal of a single-phase traction network, and any negative AC output terminal is connected to the negative terminal of a single-phase traction network.

[0064] Specifically, in this exemplary embodiment, as shown in Figures 4 to 6, the input to the entire through-power supply system is a three-phase power grid, with each phase having an input voltage of u. a / u b / u c Each input voltage is converted from three-phase to single-phase through a cascaded unit and then fed into the single-phase traction network to supply power to the locomotives running on the single-phase traction network.

[0065] In this exemplary embodiment, the cascaded unit is implemented using a hybrid topology of unloaded unit, isolated unit, and non-isolated unit. First, there are two types of cascaded units, namely a voltage regulation conversion module and a short-circuit path blocking module. There are two short-circuit path blocking modules located on one or both sides of the voltage regulation conversion module. The exemplary embodiment shown in Figure 4 shows the short-circuit path blocking module located on the front side of the voltage regulation conversion module. The exemplary embodiment shown in Figure 5 shows the short-circuit path blocking module located on the rear side of the voltage regulation conversion module. The exemplary embodiment shown in Figure 6 shows the short-circuit path blocking module located on both sides of the voltage regulation conversion module, that is, the two ends of the voltage regulation conversion module are respectively connected to the first short-circuit path blocking module and the second short-circuit path blocking module.

[0066] The specific connection relationships are as follows:

[0067] One of the three directions of the power grid (u a / u b / u c It is connected to the positive AC input terminal of the first unit in the cascaded unit, specifically u in the exemplary embodiment of FIG4. a (Through inductor L1) it is connected to the A1P terminal of the short-circuit path blocking module, specifically u in the exemplary embodiment of Figure 5. a (Through inductor L1) it is connected to the A5P terminal of the voltage regulation conversion module, specifically u in the exemplary embodiment of Figure 6. a (Through inductor L1) it is connected to the A1P terminal of the first short-circuit path blocking module.

[0068] The negative AC input terminal of the last unit in the cascaded unit is grounded. In the exemplary embodiment of FIG4, this is specifically grounded at the A10N terminal of the voltage regulation conversion module. In the exemplary embodiment of FIG5, this is specifically grounded at the A15N terminal of the short-circuit path blocking module. In the exemplary embodiment of FIG6, this is specifically grounded at the A15N terminal of the second short-circuit path blocking module.

[0069] In the cascaded units, the negative AC input terminal of the preceding unit is connected to the positive AC input terminal of the following unit. In the exemplary embodiment of FIG4, specifically, the A1N terminal of the first unit is connected to the A2P terminal of the second unit, and so on up to the A9N terminal of the ninth unit and the A10P terminal of the tenth unit. In the exemplary embodiment of FIG5, specifically, the A5N terminal of the fifth unit is connected to the A6P terminal of the sixth unit, and so on up to the A14N terminal of the fourteenth unit and the A15P terminal of the fifteenth unit. In the exemplary embodiment of FIG6, specifically, the A1N terminal of the first unit is connected to the A2P terminal of the second unit, and so on up to the A14N terminal of the fourteenth unit and the A15P terminal of the fifteenth unit.

[0070] In the cascaded units, the negative AC output terminal of the previous unit is connected to the positive AC output terminal of the next unit. In the exemplary embodiment of FIG4, specifically, the B3N terminal of the third unit is connected to the B4P terminal of the fourth unit, and so on up to the B9N terminal of the ninth unit and the B10P terminal of the tenth unit. In the exemplary embodiment of FIG5, specifically, the B5N terminal of the fifth unit is connected to the B6P terminal of the sixth unit, and so on up to the B12N terminal of the twelfth unit and the B13P terminal of the thirteenth unit. In the exemplary embodiment of FIG6, specifically, the B3N terminal of the third unit is connected to the B4P terminal of the fourth unit, and so on up to the B12N terminal of the twelfth unit and the B13P terminal of the thirteenth unit.

[0071] Any one of the AC positive output terminals is connected to the positive terminal of the single-phase traction network, and any one of the AC negative output terminals is connected to the negative terminal of the single-phase traction network. In the exemplary embodiment of FIG4, the B3P terminal of the short-circuit path blocking module is connected to the positive terminal of the single-phase traction network, and the B10N terminal of the voltage regulation and conversion module is connected to the negative terminal of the single-phase traction network. In the exemplary embodiment of FIG5, the B5P terminal of the voltage regulation and conversion module is connected to the positive terminal of the single-phase traction network, and the B13N terminal of the short-circuit path blocking module is connected to the negative terminal of the single-phase traction network. In the exemplary embodiment of FIG6, the B3P terminal of the first short-circuit path blocking module is connected to the positive terminal of the single-phase traction network, and the B13N terminal of the second short-circuit path blocking module is connected to the negative terminal of the single-phase traction network.

[0072] Specifically, in this exemplary embodiment, the non-isolated unit and the isolated unit jointly realize voltage conversion or adjustment, and the unloaded unit and the isolated unit realize the function of blocking short circuit paths. It should be explained in detail that:

[0073] The unloaded unit primarily extends the phase shift angle range of the proposed DC-DC converter by blocking short-circuit paths. However, due to the influence of voltage equalization issues, its phase shift angle range is still limited when operating alone. The isolation unit not only blocks short-circuit paths, thus further extending the phase shift angle range of the DC-DC converter, but more importantly, it also enhances the voltage equalization capability of the DC-DC converter within the isolation unit. Through voltage equalization, it can equalize the voltage of the unloaded unit, thereby improving the stability and performance of the entire system. The isolation unit and the unloaded unit complement each other. From the perspective of extending the phase shift angle, both the unloaded unit and the isolation unit can block short-circuit paths, thus extending the phase shift angle of the converter.

[0074] In other words, when the unloaded unit, the isolation unit, and the non-isolated unit are connected according to the above connection relationship, they together constitute a hybrid topology through-power supply system. In this system, the unloaded unit and the isolation unit extend the phase shift angle range of the DC-DC converter and improve the system stability by blocking short-circuit paths and enhancing voltage equalization capabilities; while the non-isolated unit is responsible for specific functions such as voltage conversion or adjustment. These three units cooperate with each other to complete the overall function of the circuit system.

[0075] Meanwhile, compared to the through-power supply scheme using a power frequency transformer for voltage reduction as shown in Figure 1 in the prior art, this exemplary embodiment eliminates the power frequency transformer, reducing system size and weight. Since energy is no longer transferred through the power frequency transformer, system losses are significantly reduced and system efficiency is improved. Compared to the PET scheme shown in Figure 2 in the prior art, the topology proposed in this exemplary embodiment reduces the number of output inverters and isolated DC-DC converters, thereby reducing energy transfer in the DC-DC converters. Therefore, compared to the PET scheme, system cost is reduced, system losses are reduced, and system efficiency is improved. Compared to the MMC scheme shown in Figure 3 in the prior art, the number of modules required is reduced, lowering cost requirements.

[0076] It should be noted that:

[0077] (1) Non-isolated units need to be cascaded. The unloaded unit and the isolated unit need to be located at either end or both ends of the voltage regulation and conversion module formed by the non-isolated units. They are similar. However, neither of them can be located between non-isolated units, otherwise they will not block the short circuit path.

[0078] (2) The unloaded units and isolation units can also be distributed in any order at any end or both ends of the voltage regulation and conversion module composed of non-isolated units. That is, multiple unloaded units and multiple isolation units can be distributed continuously as shown in Figures 4 to 6, or they can be distributed in a cross manner. When distributed in a cross manner, unloaded units may be set between isolation units and between isolation units and non-isolated units. In this case: when an unloaded unit is set between isolation units, the negative AC output terminal of the previous isolation unit is connected to the positive AC output terminal of the next isolation unit; when an unloaded unit is set between an isolation unit and a non-isolated unit, the negative AC output terminal of the isolation unit is connected to the positive AC output terminal of the non-isolated unit. That is to say, as long as the AC side of the cascaded unit is connected to the negative AC output terminal of the previous unit and the positive AC output terminal of the next unit, they can be connected together.

[0079] (3) The positive and negative terminals of the single-phase traction network can be connected to any AC output (corresponding to any AC positive output terminal connected to the single-phase traction network positive terminal, and any AC negative output terminal connected to the single-phase traction network negative terminal), that is, the AC positive and negative output terminals of the isolation unit, or the AC positive and negative output terminals of the non-isolation unit. Figures 4 to 6 only show the connection method at both ends, and other methods can be set according to requirements.

[0080] The following will describe in detail the preferred exemplary embodiments:

[0081] More preferably, in an exemplary embodiment, as shown in FIG4, the short-circuit path blocking module is located in front of the voltage regulation conversion module;

[0082] The positive AC input terminal of the short-circuit path blocking module is connected to one phase of the three-phase power grid; the negative AC input terminal of the short-circuit path blocking module is connected to the positive AC input terminal of the voltage regulation and conversion module; the negative AC input terminal of the voltage regulation and conversion module is grounded; the negative AC output terminal of the short-circuit path blocking module is connected to the positive AC output terminal of the voltage regulation and conversion module.

[0083] The positive AC input of the short-circuit path blocking module is the positive AC input of the first blocking unit, and the negative AC input of the short-circuit path blocking module is the negative AC input of the last blocking unit. The positive AC input of the voltage regulation and conversion module is the positive AC input of the first non-isolated unit, and the negative AC input of the voltage regulation and conversion module is the negative AC input of the last non-isolated unit. The negative AC output of the short-circuit path blocking module is the negative AC output of the last blocking unit, and the positive AC output of the voltage regulation and conversion module is the positive AC output of the first non-isolated unit.

[0084] Specifically, in the exemplary embodiment shown in FIG4, the short-circuit path blocking module includes four blocking units, namely two unloaded units (first unit and second unit) and two isolation units (third unit and fourth unit), and the voltage regulation and conversion module includes six non-isolated units (fifth unit to tenth unit).

[0085] The positive AC input terminal A1P of the first unit of the short-circuit path blocking module is connected to one phase of the three-phase power grid. The negative AC input terminal A4N of the fourth unit of the short-circuit path blocking module is connected to the positive AC input terminal A5P of the fifth unit of the voltage regulation and conversion module. The negative AC input terminal A10N of the tenth unit of the voltage regulation and conversion module is grounded. The negative AC output terminal B4N of the fourth unit of the short-circuit path blocking module is connected to the positive AC output terminal B5P of the fifth unit of the voltage regulation and conversion module.

[0086] In units one through ten, the positive AC output of the previous unit is connected to the positive AC input of the next unit (e.g., A3N is connected to A4P), the positive AC output B3P of the third unit is connected to the positive terminal of the single-phase traction network, and the negative AC output B10N of the tenth unit is connected to the negative terminal of the single-phase traction network.

[0087] More preferably, in an exemplary embodiment, as shown in FIG5, the short-circuit path blocking module is located behind the voltage regulation conversion module;

[0088] The positive AC input terminal of the voltage regulation and conversion module is connected to one phase of the three-phase power grid; the negative AC input terminal of the voltage regulation and conversion module is connected to the positive AC input terminal of the short-circuit path blocking module; the negative AC input terminal of the short-circuit path blocking module is grounded; the negative AC output terminal of the voltage regulation and conversion module is connected to the positive AC output terminal of the short-circuit path blocking module.

[0089] The positive AC input of the voltage regulator module is the positive AC input of the first non-isolated unit, and the negative AC input of the voltage regulator module is the negative AC input of the last non-isolated unit. The positive AC input of the short-circuit path blocking module is the positive AC input of the first blocking unit, and the negative AC input of the short-circuit path blocking module is the negative AC input of the last blocking unit. The negative AC output of the voltage regulator module is the negative AC output of the last non-isolated unit, and the positive AC output of the short-circuit path blocking module is the positive AC output of the first blocking unit.

[0090] Specifically, in the exemplary embodiment shown in FIG5, the voltage regulation conversion module includes six non-isolated units (units 5 to 10), and the short-circuit path blocking module includes five blocking units, namely three isolated units (units 11, 12 and 13) and two unloaded units (units 14 and 15).

[0091] The AC positive input terminal A5P of the fifth unit of the voltage regulation and conversion module is connected to one phase of the three-phase power grid. The AC negative input terminal A10N of the tenth unit of the voltage regulation and conversion module is connected to the AC positive input terminal A11P of the eleventh unit of the short-circuit path blocking module. The AC negative input terminal A15N of the fifteenth unit of the short-circuit path blocking module is grounded. The AC negative output terminal B10N of the tenth unit of the voltage regulation and conversion module is connected to the AC positive output terminal B11P of the eleventh unit of the short-circuit path blocking module.

[0092] In units 5 through 15, the positive AC output terminal of the previous unit is connected to the positive AC input terminal of the next unit (e.g., A7N terminal is connected to A8P terminal), the positive AC output terminal B5P terminal of unit 5 is connected to the positive terminal of the single-phase traction network, and the negative AC output terminal B13N terminal of unit 13 is connected to the negative terminal of the single-phase traction network.

[0093] More preferably, in an exemplary embodiment, as shown in FIG6, the short-circuit path blocking module is located on both sides of the voltage regulation and conversion module, that is, the two ends of the voltage regulation and conversion module are respectively connected to the first short-circuit path blocking module and the second short-circuit path blocking module.

[0094] The positive AC input terminal of the first short-circuit path blocking module is connected to one phase of the three-phase power grid. The negative AC input terminal of the first short-circuit path blocking module is connected to the positive AC input terminal of the voltage regulation and conversion module. The negative AC input terminal of the voltage regulation and conversion module is connected to the positive AC input terminal of the second short-circuit path blocking module. The negative AC input terminal of the second short-circuit path blocking module is grounded. The negative AC output terminal of the first short-circuit path blocking module is connected to the positive AC output terminal of the voltage regulation and conversion module. The negative AC output terminal of the voltage regulation and conversion module is connected to the positive AC output terminal of the second short-circuit path blocking module.

[0095] The positive AC input terminal of the first short-circuit path blocking module is the positive AC input terminal of the first blocking unit in the first short-circuit path blocking module, and the negative AC input terminal of the first short-circuit path blocking module is the negative AC input terminal of the last blocking unit in the first short-circuit path blocking module. The positive AC input terminal of the voltage regulation and conversion module is the positive AC input terminal of the first non-isolated unit, and the negative AC input terminal of the voltage regulation and conversion module is the negative AC input terminal of the last non-isolated unit. The positive AC input terminal of the second short-circuit path blocking module is the positive AC input terminal of the first blocking unit in the second short-circuit path blocking module, and the negative AC input terminal of the second short-circuit path blocking module is the negative AC input terminal of the last blocking unit in the second short-circuit path blocking module.

[0096] The negative AC output of the first short-circuit path blocking module is the negative AC output of the last blocking unit in the first short-circuit path blocking module; the positive AC output of the voltage regulation and conversion module is the positive AC output of the first non-isolated unit; the negative AC output of the voltage regulation and conversion module is the negative AC output of the last non-isolated unit; and the positive AC output of the second short-circuit path blocking module is the positive AC output of the first blocking unit in the second short-circuit path blocking module.

[0097] Specifically, in the exemplary embodiment shown in FIG6, the first short-circuit path blocking module includes four blocking units, namely two unloaded units (first unit and second unit) and two isolation units (third unit and fourth unit), the voltage regulation and conversion module includes six non-isolated units (fifth unit to tenth unit), and the second short-circuit path blocking module includes five blocking units, namely three isolation units (eleventh unit, twelfth unit and thirteenth unit) and two unloaded units (fourteenth unit and fifteenth unit).

[0098] The positive AC input terminal A1P of the first unit of the first short-circuit path blocking module is connected to one phase of the three-phase power grid. The negative AC input terminal A4N of the fourth unit of the first short-circuit path blocking module is connected to the positive AC input terminal A5P of the fifth unit of the voltage regulation and conversion module. The negative AC input terminal A10N of the tenth unit of the voltage regulation and conversion module is connected to the positive AC input terminal A11P of the eleventh unit of the second short-circuit path blocking module. The negative AC input terminal A15N of the fifteenth unit of the second short-circuit path blocking module is grounded. The negative AC output terminal B4N of the fourth unit of the first short-circuit path blocking module is connected to the positive AC output terminal B5P of the fifth unit of the voltage regulation and conversion module. The negative AC output terminal B10N of the tenth unit of the voltage regulation and conversion module is connected to the positive AC output terminal B11P of the eleventh unit of the second short-circuit path blocking module.

[0099] In units one through fifteen, the positive AC output terminal of the previous unit is connected to the positive AC input terminal of the next unit (e.g., A12N terminal is connected to A13P terminal), the positive AC output terminal B3P terminal of the third unit is connected to the positive terminal of the single-phase traction network, and the negative AC output terminal B13N terminal of the thirteenth unit is connected to the negative terminal of the single-phase traction network.

[0100] More preferably, in an exemplary embodiment, as shown in Figures 4 to 6, the non-isolated unit includes a first rectifier, a first capacitor (C5 to C10, where C6 to C9 are not shown in the figures), and a first inverter;

[0101] The positive output terminal of the first rectifier is connected to the positive input terminal of the first inverter to form a first path, the negative output terminal of the first rectifier is connected to the negative input terminal of the first inverter to form a second path, and the first capacitor is connected between the first path and the second path.

[0102] The positive input terminal of the first rectifier serves as the positive AC input terminal of the non-isolated unit, the negative input terminal of the first rectifier serves as the negative AC input terminal of the non-isolated unit, the positive output terminal of the first inverter serves as the positive AC output terminal of the non-isolated unit, and the negative output terminal of the first inverter serves as the negative AC output terminal of the non-isolated unit.

[0103] Specifically, in this exemplary embodiment, a specific implementation of the non-isolated unit is disclosed. Taking the voltage regulation conversion module in FIG4 as an example (the implementation in FIG5 and FIG6 is the same), the fifth unit is a non-isolated unit. The fifth unit includes a first rectifier, a capacitor C5 (i.e., the first capacitor of the fifth unit) and a first inverter. The AC positive input terminal A5P of the first rectifier is the AC positive input terminal of the fifth unit, the AC negative input terminal A5N of the first rectifier is the AC negative input terminal of the fifth unit, the positive output terminal B5P of the first inverter is the AC positive output terminal of the fifth unit, and the negative output terminal B5N of the first inverter is the AC negative output terminal of the fifth unit.

[0104] It should be noted that:

[0105] (1) The positive input terminal of the non-isolated unit (i.e., the positive input terminal of the first rectifier) ​​has multiple connection methods:

[0106] The positive input terminal of the first rectifier is connected to the negative input terminal of the first rectifier of the previous non-isolated unit: In the non-isolated unit shown in Figure 4, the AC positive input terminal A6P of the first rectifier in the sixth unit is connected to the AC negative input terminal A5N of the first rectifier in the fifth unit;

[0107] The positive input terminal of the first rectifier is connected to the negative input terminal of the blocking unit closest to the voltage regulation conversion module in the short-circuit path blocking module. In the non-isolated unit shown in Figure 4, the AC positive input terminal A5P of the first rectifier in the fifth unit is connected to the AC negative input terminal A4N of the fourth unit (the blocking unit closest to the voltage regulation conversion module).

[0108] The positive input terminal of the first rectifier is connected to one of the three phases of the power grid (u). a / u b / u c In the non-isolated unit shown in Figure 5, the AC positive input terminal A5P of the first rectifier in the fifth unit is connected to the three-phase power grid. a Towards.

[0109] (2) The negative input terminal of the non-isolated unit (i.e., the negative input terminal of the first rectifier) ​​has multiple connection methods:

[0110] The negative input terminal of the first rectifier is connected to the positive input terminal of the first rectifier of the next non-isolated unit: In the non-isolated unit shown in Figure 5, the AC negative input terminal A5N of the first rectifier in the fifth unit is connected to the AC positive input terminal A6P of the first rectifier in the sixth unit;

[0111] The negative input terminal of the first rectifier is connected to the positive input terminal of the blocking unit closest to the voltage regulation and conversion module in the short-circuit path blocking module. In the non-isolated unit shown in Figure 5, the AC negative input terminal A10N of the first rectifier in the tenth unit is connected to the AC positive input terminal A11P of the eleventh unit (the blocking unit closest to the voltage regulation and conversion module).

[0112] The negative input terminal of the first rectifier is grounded: In the non-isolated unit shown in Figure 4, the AC negative input terminal A10N of the first rectifier in the tenth unit is grounded.

[0113] (3) The AC positive output terminal of the non-isolated unit (i.e., the positive output terminal of the first inverter) has multiple connection methods:

[0114] The positive output terminal of the first inverter is connected to the negative output terminal of the first inverter of the previous non-isolated unit: In the non-isolated unit shown in Figure 4, the AC positive input terminal B6P of the first inverter in the sixth unit is connected to the AC negative input terminal B5N of the first inverter in the fifth unit.

[0115] The positive output terminal of the first inverter is connected to the negative output terminal of the blocking unit closest to the voltage regulation conversion module in the short-circuit path blocking module. In the non-isolated unit shown in Figure 4, the AC positive output terminal B5P of the first inverter in the fifth unit is connected to the AC negative input terminal B4N of the fourth unit (the blocking unit closest to the voltage regulation conversion module).

[0116] The positive output terminal of the first inverter is connected to the positive terminal of the single-phase traction network: In the non-isolated unit shown in Figure 5, the AC positive output terminal B5P of the first inverter in the fifth unit is connected to the positive terminal of the single-phase traction network.

[0117] (4) The negative output terminal of the non-isolated unit (i.e., the negative output terminal of the first inverter) has multiple connection methods:

[0118] The negative output terminal of the first inverter is connected to the positive output terminal of the first inverter of the next non-isolated unit: In the non-isolated unit shown in Figure 5, the AC negative output terminal B5N of the first inverter in the fifth unit is connected to the AC positive output terminal B6P of the first inverter in the sixth unit.

[0119] The negative output terminal of the first inverter is connected to the positive output terminal of the blocking unit closest to the voltage regulation conversion module in the short-circuit path blocking module. In the non-isolated unit shown in Figure 5, the AC negative output terminal B10N of the first inverter in the tenth unit is connected to the AC positive output terminal B11P of the eleventh unit (the blocking unit closest to the voltage regulation conversion module).

[0120] The negative output terminal of the first inverter is connected to the negative terminal of the single-phase traction network: In the non-isolated unit shown in Figure 4, the AC negative output terminal B10N of the first inverter in the tenth unit is connected to the negative terminal of the single-phase traction network.

[0121] More preferably, in an exemplary embodiment, as shown in Figures 4 to 6, the unloaded unit includes a second rectifier and a second capacitor (C1 / C2 / C14 / C15);

[0122] The positive and negative output terminals of the second rectifier serve as the unused terminals of the unloaded unit, and the second capacitor is connected between the positive and negative output terminals of the second rectifier.

[0123] The positive input terminal of the second rectifier serves as the AC positive input terminal of the no-load unit, and the negative input terminal of the second rectifier serves as the AC negative input terminal of the no-load unit.

[0124] Specifically, in this exemplary embodiment, a specific implementation of the unloaded unit is disclosed. Taking the short-circuit path blocking module in FIG4 as an example (the implementation in FIG5 and FIG6 is the same), the second unit is an unloaded unit. The second unit includes a second rectifier and a capacitor C2. The AC positive input terminal A2P of the second rectifier is the AC positive input terminal of the second unit, the AC negative input terminal A2N of the second rectifier is the AC negative input terminal of the second unit, and the positive output terminal and negative output terminal of the second rectifier are the unloaded terminals of the unloaded unit.

[0125] It should be noted that:

[0126] (1) The AC positive input terminal of the unloaded unit (i.e., the positive input terminal of the second rectifier) ​​has multiple connection methods:

[0127] The positive input terminal of the second rectifier is connected to the negative input terminal of the previous blocking unit: In the unloaded unit shown in Figure 4, the AC positive input terminal A2P of the second rectifier in the second unit is connected to the AC negative input terminal A1N of the first unit (blocking unit, which is also another unloaded unit).

[0128] The positive input terminal of the second rectifier is connected to one phase of the power grid: In the unloaded unit shown in Figure 4, the AC positive input terminal A1P of the second rectifier in the first unit is connected to the three-phase power grid. a Towards.

[0129] The positive input terminal of the second rectifier is connected to the negative input terminal of the voltage regulation conversion module: This can be achieved in the unloaded unit shown in Figure 5 when one of the unloaded modules is located after the voltage regulation conversion module.

[0130] (2) The AC negative input terminal of the unloaded unit (i.e., the negative input terminal of the second rectifier) ​​has multiple connection methods:

[0131] The negative input terminal of the second rectifier is connected to the positive input terminal of the next blocking unit: In the unloaded unit shown in Figure 5, the AC negative input terminal A14N of the second rectifier in the fourteenth unit is connected to the AC positive input terminal A15N of the fifteenth unit (blocking unit, which is also another unloaded unit).

[0132] The negative input terminal of the second rectifier is grounded: In the unloaded unit shown in Figure 5, the AC negative input terminal A15N of the second rectifier in the fifteenth unit is grounded.

[0133] The negative input terminal of the second rectifier is connected to the positive input terminal of the voltage regulation conversion module: This can be achieved in the unloaded unit shown in Figure 4 when one of the unloaded modules is located before the voltage regulation conversion module.

[0134] More preferably, in an exemplary embodiment, as shown in Figures 4 to 6, the isolation unit includes a third rectifier, a DC-DC converter, a second inverter, a third capacitor (C31 / C41 / C111 / C121 / C131), and a fourth capacitor (C32 / C42 / C112 / C122 / C132).

[0135] The positive output terminal of the third rectifier is connected to the positive input terminal of the DC-DC converter to form the third path. The negative output terminal of the third rectifier is connected to the negative input terminal of the DC-DC converter to form the fourth path. The positive output terminal of the DC-DC converter is connected to the positive input terminal of the second inverter to form the fifth path. The negative output terminal of the DC-DC converter is connected to the negative input terminal of the second inverter to form the sixth path. The third capacitor is connected between the third and fourth paths, and the fourth capacitor is connected between the fifth and sixth paths.

[0136] The positive input terminal of the third rectifier serves as the AC positive input terminal of the isolation unit, and the negative input terminal of the third rectifier serves as the AC negative input terminal of the isolation unit; the positive output terminal of the second inverter serves as the AC positive output terminal of the isolation unit, and the negative output terminal of the second inverter serves as the AC negative output terminal of the isolation unit.

[0137] Specifically, in this exemplary embodiment, a specific implementation of the isolation unit is disclosed. Taking the short-circuit path blocking module in FIG4 as an example (the implementation in FIG5 and FIG6 is the same), the third unit is an isolation unit, which includes a third rectifier, a DC-DC converter, capacitor C31, capacitor C32, and a second inverter. The AC positive input terminal A3P of the third rectifier is the AC positive input terminal of the third unit, and the AC negative input terminal A3N of the third rectifier is the AC negative input terminal of the third unit. The positive output terminal B3P of the second inverter is the AC positive output terminal of the third unit, and the negative output terminal B3N of the second inverter is the AC negative output terminal of the third unit. The DC-DC converter is disposed between the third rectifier and the second inverter.

[0138] It should be noted that:

[0139] (1) The positive input terminal of the isolation unit (i.e., the positive input terminal of the third rectifier) ​​has multiple connection methods:

[0140] The positive input terminal of the third rectifier is connected to the negative input terminal of the previous blocking unit: In the isolation unit shown in Figure 4, the AC positive input terminal A4P of the third rectifier in the fourth unit is connected to the AC negative input terminal A3N of the third rectifier in the third unit.

[0141] The positive input terminal of the third rectifier is connected to the negative input terminal of the voltage regulation and conversion module: In the isolation unit shown in Figure 5, the AC positive input terminal A11P of the third rectifier in the eleventh unit is connected to the AC negative input terminal A10N of the tenth unit.

[0142] The positive input terminal of the third rectifier is connected to one phase of the power grid: This can be achieved when the isolation unit is the first in the short-circuit path blocking module, as shown in Figure 4.

[0143] (2) The AC negative input terminal of the isolation unit (i.e., the negative input terminal of the third rectifier) ​​has multiple connection methods:

[0144] The negative input terminal of the third rectifier is connected to the positive input terminal of the next blocking unit: In the isolation unit shown in Figure 5, the AC negative input terminal A11N of the third rectifier in the eleventh unit is connected to the AC positive input terminal A12P of the third rectifier in the twelfth unit.

[0145] The negative input terminal of the third rectifier is connected to the positive input terminal of the voltage regulation and conversion module. In the isolation unit shown in Figure 4, the AC negative input terminal A4N of the third rectifier in the fourth unit is connected to the AC positive input terminal A5P of the fifth unit of the voltage regulation and conversion module.

[0146] Grounding the negative input terminal of the third rectifier can be achieved in the isolation unit shown in Figure 5, when the isolation unit is the last one in the short-circuit path blocking module.

[0147] (3) The AC positive output terminal of the isolation unit (i.e., the positive output terminal of the second inverter) has multiple connection methods:

[0148] The positive output terminal of the second inverter is connected to the negative output terminal of the previous blocking unit: In the non-isolated unit shown in Figure 4, the AC positive input terminal B4P of the second inverter in the fourth unit is connected to the AC negative input terminal B3N of the second inverter in the third unit.

[0149] The positive output terminal of the second inverter is connected to the negative output terminal of the voltage regulation and conversion module: In the isolation unit shown in Figure 5, the AC positive output terminal B11P of the second inverter in the eleventh unit is connected to the AC negative input terminal B10N of the tenth unit of the voltage regulation and conversion module.

[0150] The positive output terminal of the second inverter is connected to the positive terminal of the single-phase traction network: In the isolation unit shown in Figure 4, the AC positive output terminal B3P of the second inverter in the third unit is connected to the positive terminal of the single-phase traction network.

[0151] (4) The AC negative output terminal of the isolation unit (i.e., the negative output terminal of the second inverter) has multiple connection methods:

[0152] The negative output terminal of the second inverter is connected to the positive output terminal of the next blocking unit: In the isolation unit shown in Figure 5, the AC negative output terminal B11N of the second inverter in the eleventh unit is connected to the AC positive output terminal B12P of the second inverter in the twelfth unit.

[0153] The negative output terminal of the second inverter is connected to the positive output terminal of the voltage regulation and conversion module. In the isolation unit shown in Figure 4, the AC negative output terminal B4N of the second inverter in the fourth unit is connected to the AC positive output terminal B5P of the fifth unit of the voltage regulation and conversion module.

[0154] The negative output terminal of the second inverter is connected to the negative terminal of the single-phase traction network: In the isolation unit shown in Figure 5, the AC negative output terminal B13N of the second inverter in the thirteenth unit is connected to the negative terminal of the single-phase traction network.

[0155] Referring to Figure 7, Figure 7 shows a flowchart of a design method for a hybrid topology through-power supply system based on the first aspect of the present invention, provided in another exemplary embodiment of the present invention, including the following steps:

[0156] S01: Determine the total number of non-isolated units, no-load units and isolated units in the cascaded unit: Obtain the line voltage connected to the power grid and convert the line voltage into the phase voltage. At the same time, obtain the voltage withstand limit of the switching transistors of the input rectifier in the non-isolated unit, no-load unit and isolated unit. Calculate the total number of non-isolated units, no-load units and isolated units according to the ratio of the phase voltage and the voltage withstand limit of the switching transistors.

[0157] S03: Determine the number of unloaded units: Based on the pressure equalization boundary setting, set the number of units in the first proportion of the total cascaded number that are in an unloaded state, i.e., the number of unloaded units.

[0158] S05: Determine the number of isolation units: Based on the available vector to meet the traction power supply requirements, set the number of units in the second proportion of the total cascaded number to block short-circuit paths, i.e., the number of unloaded units and isolation units. The number of isolation units is obtained by subtracting the number of units in the first proportion from the number of units in the second proportion.

[0159] S07: Determine the number of non-isolated units: The number of non-isolated units is obtained by subtracting the total number of cascades from the total number of cascades by a second ratio.

[0160] Specifically, in this exemplary embodiment, in order to meet the requirements of various traction loads on the converter vector boundary and ensure the stable operation of the system under various harsh environments, a design method for a hybrid topology through-power supply system is disclosed, mainly involving the calculation method of the number of unloaded units, isolated units, and non-isolated units:

[0161] S01: When the input is a 110kV line voltage, the corresponding phase voltage is 63.5kV. Considering the voltage withstand capability limitation of the existing 6.5kV switching transistor, 15 three-level modules need to be cascaded to meet the 63.5kV phase voltage requirement.

[0162] S03: During the module cascading process, based on the setting of the equalization boundary, the system can allow 1 / 3 of the modules to be in an unloaded state. In order to leave sufficient safety margin, the number of unloaded units is selected as 4.

[0163] S05: To ensure that the available vector power supply meets the traction power supply requirements, and to ensure the stability and reliability of the system, the number of unloaded units plus isolation units in the 15 cascaded modules is set to 9. Therefore, in addition to the already configured 4 unloaded units, 5 additional isolation units are required. Specifically, in addition to configuring 4 unloaded units, 5 isolation units with isolated DC-DC converters are needed to meet the phase angle difference required for continuous power supply; therefore, the number of unloaded units plus isolation units is set to 9.

[0164] S07: The number of non-isolated units is 15-9=6.

[0165] Figure 6 shows the hybrid topology obtained by the design method. Each phase consists of 15 cascaded modules. The wiring can preferably be the same. The input terminals of the three cascaded modules are directly connected to the power grid, and the output terminals of the three inverters are first connected in series, then in parallel, and then connected to the single-phase traction network.

[0166] More preferably, in an exemplary embodiment, as shown in FIG8, the method further includes the following steps:

[0167] S09: Determine the number of full-bridge and half-bridge units in the output inverter, including:

[0168] S0901: The input-output ratio is obtained based on the input phase voltage and the output voltage;

[0169] S0903: Set the input rectifier to a full-bridge structure, and obtain the number of equivalent full-bridge structures of the output inverter based on the total number of cascaded units and the input-output ratio;

[0170] S0905: The total number of output inverters is obtained by adding the number of isolated units and the number of non-isolated units. The equivalent number of full-bridge structures is obtained by configuring full-bridge and half-bridge structures according to the total number of output inverters. During the configuration process, a half-bridge unit is equivalent to 0.5 full-bridge units.

[0171] Specifically, in this exemplary embodiment, the number of full-bridge and half-bridge modules also needs to be further configured:

[0172] S0901: Converts the phase voltage from 63.5kV to the output voltage of 27.5kV with a transformation ratio of 2.3.

[0173] S0903: When the input consists of 15 full-bridge modules, the theoretical number of output modules required is 6.5 full-bridge modules.

[0174] S0905: A half-bridge module can be equivalent to 0.5 full-bridge modules. Therefore, it is necessary to approximate the required 6.5 full-bridge modules by reasonably configuring the half-bridge and full-bridge modules. Since 4 of the 15 total modules have been determined to be unloaded modules, 9 half-bridge modules and 2 full-bridge modules are selected from the remaining 11 modules, thus effectively configuring 6.5 full-bridge modules.

[0175] In summary, the system is configured as follows: each phase input consists of 15 cascaded modules, and of the outputs of the 15 modules, 4 are unloaded units, and of the remaining 11 non-unloaded units, 5 are isolated units and 6 are non-isolated units. The outputs of the 11 non-unloaded units are 9 half-bridges (5 of which have isolated units) and 2 are full-bridges.

[0176] This configuration satisfies both voltage and power requirements while ensuring system stability and reliability. Furthermore, when applied to other fields, the same method can be used to determine the number of cascaded modules, the number of isolated DC-DC converters, and the number of full-bridge and half-bridge modules.

[0177] In addition, it should be noted that the above-mentioned module structure can also be used in fields such as three-phase to three-phase high-voltage frequency converters, two-phase to single-phase continuous power supply systems and single-phase to single-phase same-phase power supply systems.

[0178] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A hybrid topology through-type power supply system, comprising three cascaded units connecting a three-phase power grid and a single-phase traction network; characterized in that: Each cascaded unit includes a voltage regulation and conversion module and a short-circuit path blocking module. The voltage regulation and conversion module includes several non-isolated units, and the short-circuit path blocking module includes several blocking units. The blocking units include several unloaded units and several isolated units. Each non-isolated unit and isolated unit includes an AC positive input terminal, an AC negative input terminal, an AC positive output terminal, and an AC negative output terminal. Each unloaded unit includes an AC positive input terminal, an AC negative input terminal, and an unused terminal. The short-circuit path blocking module is located on one or both sides of the voltage regulation and conversion module, and the unloaded unit, isolation unit and non-isolation unit are arranged in sequence according to their positional relationship. In a cascaded unit, the positive AC input terminal of the first unit is connected to one phase of the three-phase power grid, and the negative AC input terminal of the last unit is grounded. The negative AC input terminal of the preceding unit in a cascaded unit is connected to the positive AC input terminal of the following unit, and the negative AC output terminal of the preceding unit in a cascaded unit is connected to the positive AC output terminal of the following unit. Any positive AC output terminal is connected to the positive terminal of a single-phase traction network, and any negative AC output terminal is connected to the negative terminal of a single-phase traction network.

2. The hybrid topology through-power supply system according to claim 1, characterized in that: The short-circuit path blocking module is located in front of the voltage regulation and conversion module; The positive AC input terminal of the short-circuit path blocking module is connected to one phase of the three-phase power grid; the negative AC input terminal of the short-circuit path blocking module is connected to the positive AC input terminal of the voltage regulation and conversion module; the negative AC input terminal of the voltage regulation and conversion module is grounded; the negative AC output terminal of the short-circuit path blocking module is connected to the positive AC output terminal of the voltage regulation and conversion module. The positive AC input of the short-circuit path blocking module is the positive AC input of the first blocking unit, and the negative AC input of the short-circuit path blocking module is the negative AC input of the last blocking unit. The positive AC input of the voltage regulation and conversion module is the positive AC input of the first non-isolated unit, and the negative AC input of the voltage regulation and conversion module is the negative AC input of the last non-isolated unit. The negative AC output of the short-circuit path blocking module is the negative AC output of the last blocking unit, and the positive AC output of the voltage regulation and conversion module is the positive AC output of the first non-isolated unit.

3. The hybrid topology through-power supply system according to claim 1, characterized in that: The short-circuit path blocking module is located behind the voltage regulation and conversion module; The positive AC input terminal of the voltage regulation and conversion module is connected to one phase of the three-phase power grid; the negative AC input terminal of the voltage regulation and conversion module is connected to the positive AC input terminal of the short-circuit path blocking module; the negative AC input terminal of the short-circuit path blocking module is grounded; the negative AC output terminal of the voltage regulation and conversion module is connected to the positive AC output terminal of the short-circuit path blocking module. The positive AC input of the voltage regulator module is the positive AC input of the first non-isolated unit, and the negative AC input of the voltage regulator module is the negative AC input of the last non-isolated unit. The positive AC input of the short-circuit path blocking module is the positive AC input of the first blocking unit, and the negative AC input of the short-circuit path blocking module is the negative AC input of the last blocking unit. The negative AC output of the voltage regulator module is the negative AC output of the last non-isolated unit, and the positive AC output of the short-circuit path blocking module is the positive AC output of the first blocking unit.

4. The hybrid topology through-power supply system according to claim 1, characterized in that: The short-circuit path blocking module is located on both sides of the voltage regulation and conversion module, that is, the two ends of the voltage regulation and conversion module are respectively connected to the first short-circuit path blocking module and the second short-circuit path blocking module. The positive AC input terminal of the first short-circuit path blocking module is connected to one phase of the three-phase power grid. The negative AC input terminal of the first short-circuit path blocking module is connected to the positive AC input terminal of the voltage regulation and conversion module. The negative AC input terminal of the voltage regulation and conversion module is connected to the positive AC input terminal of the second short-circuit path blocking module. The negative AC input terminal of the second short-circuit path blocking module is grounded. The negative AC output terminal of the first short-circuit path blocking module is connected to the positive AC output terminal of the voltage regulation and conversion module. The negative AC output terminal of the voltage regulation and conversion module is connected to the positive AC output terminal of the second short-circuit path blocking module. The positive AC input terminal of the first short-circuit path blocking module is the positive AC input terminal of the first blocking unit in the first short-circuit path blocking module, and the negative AC input terminal of the first short-circuit path blocking module is the negative AC input terminal of the last blocking unit in the first short-circuit path blocking module. The positive AC input terminal of the voltage regulation and conversion module is the positive AC input terminal of the first non-isolated unit, and the negative AC input terminal of the voltage regulation and conversion module is the negative AC input terminal of the last non-isolated unit. The positive AC input terminal of the second short-circuit path blocking module is the positive AC input terminal of the first blocking unit in the second short-circuit path blocking module, and the negative AC input terminal of the second short-circuit path blocking module is the negative AC input terminal of the last blocking unit in the second short-circuit path blocking module. The negative AC output of the first short-circuit path blocking module is the negative AC output of the last blocking unit in the first short-circuit path blocking module; the positive AC output of the voltage regulation and conversion module is the positive AC output of the first non-isolated unit; the negative AC output of the voltage regulation and conversion module is the negative AC output of the last non-isolated unit; and the positive AC output of the second short-circuit path blocking module is the positive AC output of the first blocking unit in the second short-circuit path blocking module.

5. The hybrid topology through-power supply system according to any one of claims 1 to 4, characterized in that: The non-isolated unit includes a first rectifier, a first capacitor, and a first inverter; The positive output terminal of the first rectifier is connected to the positive input terminal of the first inverter to form a first path, the negative output terminal of the first rectifier is connected to the negative input terminal of the first inverter to form a second path, and the first capacitor is connected between the first path and the second path. The positive input terminal of the first rectifier serves as the positive AC input terminal of the non-isolated unit, the negative input terminal of the first rectifier serves as the negative AC input terminal of the non-isolated unit, the positive output terminal of the first inverter serves as the positive AC output terminal of the non-isolated unit, and the negative output terminal of the first inverter serves as the negative AC output terminal of the non-isolated unit.

6. The hybrid topology through-power supply system according to any one of claims 1 to 4, characterized in that: The unloaded unit includes a second rectifier and a second capacitor; The positive and negative output terminals of the second rectifier serve as the unused terminals of the unloaded unit, and the second capacitor is connected between the positive and negative output terminals of the second rectifier. The positive input terminal of the second rectifier serves as the AC positive input terminal of the no-load unit, and the negative input terminal of the second rectifier serves as the AC negative input terminal of the no-load unit.

7. The hybrid topology through-power supply system according to any one of claims 1 to 4, characterized in that: The isolation unit includes a third rectifier, a DC-DC converter, a second inverter, a third capacitor, and a fourth capacitor; The positive output terminal of the third rectifier is connected to the positive input terminal of the DC-DC converter to form the third path. The negative output terminal of the third rectifier is connected to the negative input terminal of the DC-DC converter to form the fourth path. The positive output terminal of the DC-DC converter is connected to the positive input terminal of the second inverter to form the fifth path. The negative output terminal of the DC-DC converter is connected to the negative input terminal of the second inverter to form the sixth path. The third capacitor is connected between the third and fourth paths, and the fourth capacitor is connected between the fifth and sixth paths. The positive input terminal of the third rectifier serves as the AC positive input terminal of the isolation unit, and the negative input terminal of the third rectifier serves as the AC negative input terminal of the isolation unit; the positive output terminal of the second inverter serves as the AC positive output terminal of the isolation unit, and the negative output terminal of the second inverter serves as the AC negative output terminal of the isolation unit.

8. The design method of the hybrid topology through-power supply system as described in any one of claims 1 to 7, characterized in that: Includes the following steps: Determine the total number of non-isolated units, no-load units, and isolated units in the cascaded unit: Obtain the line voltage connected to the power grid and convert the line voltage into the phase voltage. At the same time, obtain the voltage withstand limit of the switching transistors of the input rectifiers in the non-isolated units, no-load units, and isolated units. Calculate the total number of non-isolated units, no-load units, and isolated units based on the ratio of the phase voltage to the voltage withstand limit of the switching transistors. Determine the number of unloaded units: Based on the pressure equalization boundary setting, set the number of units in the first proportion of the total cascaded units to be in an unloaded state, i.e., the number of unloaded units; Determine the number of isolation units: Based on the available vector to meet the traction power supply requirements, set the second proportion of units in the total cascaded number to block short-circuit paths, i.e., the number of unloaded units and isolation units. The number of isolation units is obtained by subtracting the first proportion of units from the second proportion of units. Determine the number of non-isolated units: The number of non-isolated units is obtained by subtracting the total number of cascades from the total number of cascades by a second ratio.

9. The design method according to claim 8, characterized in that: The method further includes the following steps: Determine the number of full-bridge and half-bridge units in the output inverter, including: The input-output ratio is obtained based on the input phase voltage and the output voltage. Assuming the input rectifier is a full-bridge structure, the number of equivalent full-bridge structures for the output inverter is obtained based on the total number of cascaded units and the input-output ratio. The total number of output inverters is obtained by adding the number of isolated units and the number of non-isolated units. The number of equivalent full-bridge structures is obtained by configuring full-bridge and half-bridge structures based on the total number of output inverters. During the configuration process, a half-bridge unit is equivalent to 0.5 full-bridge units.

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