Single-phase traction power supply variable frequency power supply device and single-phase traction power supply variable frequency method

Abstract

This invention discloses a single-phase traction power supply frequency converter and a single-phase traction power supply frequency conversion method. The input-side transformer transforms the power frequency voltage to obtain N single-phase power frequency voltages. Each frequency conversion module transforms one input single-phase power frequency voltage to obtain N single-phase non-power frequency voltages with frequencies equal to the target frequency. The output-side transformer transforms the single-phase non-power frequency voltage obtained by connecting the N single-phase non-power frequency voltages in parallel to obtain a single-phase non-power frequency voltage with an output voltage equal to the target voltage, thus supplying power to trains under non-power frequency AC power supply systems. Therefore, this application can convert the power supply of domestic power frequency AC power supply systems into a single-phase non-power frequency AC power supply, thereby enabling commissioning tests on trains to be exported under foreign non-power frequency power supply systems, improving the safety and reliability of the trains to be exported. Moreover, the device of this application can be applied to frequency conversion operations using foreign power frequency voltages.

Description

Technical Field

[0001] This invention relates to the field of railway traction power supply, and in particular to a single-phase traction power supply frequency converter and a single-phase traction power supply frequency conversion method. Background Technology

[0002] Currently, domestic electrified railways use single-phase 27.5kV / 50Hz AC traction power supply, while foreign railway power supply systems are mainly divided into 25kV / 50Hz (or 25kV / 60Hz) and... There are two types. Since there are currently no electrified railways in China using non-power frequency (i.e., non-50Hz) AC power supply systems, foreign non-power frequency AC power supply methods are not applicable domestically. However, in recent years, China has gradually increased its exports of high-speed trains and electric locomotives. Given the current lack of domestic lines using non-power frequency AC power supply systems, it is impossible to conduct testing and commissioning of exported high-speed trains and electric locomotives under foreign non-power frequency power supply systems, resulting in lower safety and reliability for these exported trains and locomotives.

[0003] Therefore, how to provide a solution to the above-mentioned technical problems is a problem that those skilled in the art need to solve at present. Summary of the Invention

[0004] The purpose of this invention is to provide a single-phase traction power supply frequency conversion device and a single-phase traction power supply frequency conversion method, which can convert the power supply of the domestic power frequency AC power supply system into a single-phase non-power frequency AC power supply, thereby enabling the commissioning and testing of EMUs and electric locomotives to be exported under foreign non-power frequency power supply systems, improving the safety and reliability of EMUs and electric locomotives to be exported; moreover, the device of this application can be applied to frequency conversion operation of foreign power frequency voltage.

[0005] To solve the above-mentioned technical problems, the present invention provides a single-phase traction power supply frequency converter, comprising:

[0006] An input-side transformer for inputting power frequency voltage is used to transform the power frequency voltage to obtain N single-phase power frequency voltages; where N is a positive integer;

[0007] N frequency conversion and voltage transformation modules are connected one-to-one with the N output terminals of the input-side transformer. Each frequency conversion and voltage transformation module is used to convert the input single-phase power frequency voltage to obtain N single-phase non-power frequency voltages with a frequency equal to the target frequency.

[0008] The output-side transformer, connected to the parallel output terminals of N frequency conversion and voltage transformation modules, is used to transform the single-phase non-power frequency voltage obtained by paralleling N single-phase non-power frequency voltages to obtain a single-phase non-power frequency voltage with an output voltage equal to the target voltage, so as to supply power to the train under the non-power frequency AC power supply system.

[0009] Preferably, the frequency converter module includes a first connector, a single-phase AC-DC-AC converter, and a second connector; wherein:

[0010] The first end of the first connector is connected to one output terminal of the input-side transformer, the second end of the first connector is connected to the first AC side of the single-phase AC-DC-AC converter, the second AC side of the single-phase AC-DC-AC converter is connected to the first end of the second connector, and the second end of the second connector is connected to the input terminal of the output-side transformer; wherein, the first connector and the second connector are used to isolate the connection lines between the single-phase AC-DC-AC converter and the input-output-side transformer.

[0011] Preferably, the first connector and the second connector are specifically reactors, filters, disconnect switches, or transformers.

[0012] Preferably, the filter is an LC filter, an RC filter, or an LCL filter.

[0013] Preferably, the single-phase AC-DC-AC converter is a converter with a two-level, three-level, MMC, or cascaded topology constructed using power switching devices.

[0014] Preferably, the power switching device is a GTO, an IGBT, or a SiC.

[0015] Preferably, when the input side of the single-phase traction power supply frequency converter is connected to a three-phase power frequency voltage, the input-side transformer is specifically:

[0016] A three-phase transformer is used to transform the three-phase power frequency voltage to obtain three single-phase power frequency voltages: phase A power frequency voltage, phase B power frequency voltage, and phase C power frequency voltage.

[0017] Preferably, when the input side of the single-phase traction power supply frequency converter is connected to a single-phase power frequency voltage, the input-side transformer is specifically:

[0018] A single-phase transformer is used to transform the input single-phase power frequency voltage to obtain one single-phase power frequency voltage, and then divide the one single-phase power frequency voltage into N outputs.

[0019] Preferably, the input-side transformer and the output-side transformer are specifically oil-immersed transformers, dry-type transformers, isolation transformers, or multi-winding transformers.

[0020] Preferably, the target frequency is 60Hz or

[0021] Preferably, the single-phase traction power supply frequency converter further includes:

[0022] A controller, connected to N frequency converter modules, is used to pre-select the input-side transformer and output-side transformer connected to the N frequency converter modules according to a preset transformer selection strategy, for reference in device connection design. When the N frequency converter modules are operating, the controller controls the frequency converter operation of the N frequency converter modules according to the output voltage of the input-side transformer and the input demand voltage of the output-side transformer, so that the input voltage of the output-side transformer meets its input demand voltage.

[0023] Preferably, when selecting the input-side transformer and the output-side transformer, the controller is specifically used for:

[0024] The required input voltage and output voltage of the frequency converter module are determined based on the allowable input and output range of the frequency converter module.

[0025] The input voltage of the input transformer is determined based on the input voltage requirement of the frequency converter and the power frequency voltage pre-connected to the input side of the device.

[0026] Based on the input voltage conditions, a transformer combination that meets the input voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the input-side transformer.

[0027] The output voltage of the output-side transformer is determined based on the output voltage requirement of the frequency converter and the power supply voltage requirement of the train.

[0028] Based on the output voltage conditions, a transformer combination that satisfies the output voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the output-side transformer.

[0029] Preferably, the controller is further configured to:

[0030] Obtain the actual single-phase non-power frequency voltage output by the output-side transformer, and calculate the voltage error between the power supply demand voltage of the train and the actual single-phase non-power frequency voltage;

[0031] The frequency conversion and voltage conversion operation of the frequency conversion and voltage conversion module is adjusted accordingly based on the voltage error, so that the actual single-phase non-power frequency voltage meets the power supply requirements of the train.

[0032] To solve the above-mentioned technical problems, the present invention also provides a single-phase traction power supply frequency conversion method, applicable to any of the above-mentioned single-phase traction power supply frequency conversion power devices, wherein the single-phase traction power supply frequency conversion method includes:

[0033] The input-side transformer and output-side transformer connected to the N frequency converter and transformer modules are selected in advance according to the preset transformer selection strategy for reference in the device connection design.

[0034] When N frequency conversion and voltage conversion modules are operating, the frequency conversion and voltage conversion operation of the N frequency conversion and voltage conversion modules is controlled according to the output voltage of the input-side transformer and the input demand voltage of the output-side transformer, so that the input voltage of the output-side transformer meets its input demand voltage.

[0035] Preferably, the process of pre-selecting the input-side transformer and output-side transformer connected to the N frequency converter and transformer modules according to a preset transformer selection strategy includes:

[0036] The required input voltage and output voltage of the frequency converter module are determined based on the allowable input and output range of the frequency converter module.

[0037] The input voltage of the input transformer is determined based on the input voltage requirement of the frequency converter and the power frequency voltage pre-connected to the input side of the device.

[0038] Based on the input voltage conditions, a transformer combination that meets the input voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the input-side transformer.

[0039] The output voltage of the output-side transformer is determined based on the output voltage requirement of the frequency converter and the power supply voltage requirement of the train.

[0040] Based on the output voltage conditions, a transformer combination that satisfies the output voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the output-side transformer.

[0041] Preferably, the single-phase traction power supply frequency conversion method further includes:

[0042] Obtain the actual single-phase non-power frequency voltage output by the output-side transformer, and calculate the voltage error between the power supply demand voltage of the train and the actual single-phase non-power frequency voltage;

[0043] The frequency conversion and voltage conversion operation of the frequency conversion and voltage conversion module is adjusted accordingly based on the voltage error, so that the actual single-phase non-power frequency voltage meets the power supply requirements of the train.

[0044] This invention provides a single-phase traction power supply frequency converter, comprising an input-side transformer, N frequency conversion and voltage transformation modules, and an output-side transformer. The input-side transformer transforms the power frequency voltage to obtain N single-phase power frequency voltages. Each frequency conversion and voltage transformation module transforms one input single-phase power frequency voltage to obtain N single-phase non-power frequency voltages with frequencies equal to the target frequency. The output-side transformer transforms the single-phase non-power frequency voltage obtained by connecting the N parallel single-phase non-power frequency voltages to obtain a single-phase non-power frequency voltage with an output voltage equal to the target voltage, thus supplying power to trains under non-power frequency AC power supply systems. Therefore, this application can convert the power supply of domestic power frequency AC power supply systems into a single-phase non-power frequency AC power supply, thereby enabling commissioning tests of EMUs and electric locomotives to be exported under foreign non-power frequency power supply systems, improving the safety and reliability of exported EMUs and electric locomotives. Furthermore, the device of this application can be applied to frequency conversion operations using foreign power frequency voltages.

[0045] The present invention also provides a single-phase traction power supply frequency conversion method, which has the same beneficial effects as the above-mentioned frequency conversion power supply device. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of the structure of a single-phase traction power supply frequency converter provided in an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the structure of a frequency converter and voltage converter module provided in an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram of the structure of a single-phase traction power supply frequency converter under three-phase power frequency voltage input, provided in an embodiment of the present invention.

[0050] Figure 4 This is a schematic diagram of the structure of a single-phase traction power supply frequency converter under single-phase power frequency voltage input, provided by an embodiment of the present invention.

[0051] Figure 5 This is a schematic diagram of a power frequency voltage and a non-power frequency voltage provided for an embodiment of the present invention. Detailed Implementation

[0052] The core of this invention is to provide a single-phase traction power supply frequency conversion device and a single-phase traction power supply frequency conversion method, which can convert the power supply of the domestic power frequency AC power supply system into a single-phase non-power frequency AC power supply, thereby enabling the commissioning and testing of EMUs and electric locomotives to be exported under foreign non-power frequency power supply systems, improving the safety and reliability of EMUs and electric locomotives to be exported; moreover, the device of this application can be applied to frequency conversion operation of foreign power frequency voltage.

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments 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, 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.

[0054] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a single-phase traction power supply frequency converter provided in an embodiment of the present invention.

[0055] The single-phase traction power supply frequency converter includes:

[0056] The input-side transformer 1, which receives the power frequency voltage, is used to transform the power frequency voltage to obtain N single-phase power frequency voltages; where N is a positive integer.

[0057] N frequency conversion and voltage transformation modules 2 are connected one by one to the N output terminals of the input transformer 1. Each frequency conversion and voltage transformation module 2 is used to convert the input single-phase power frequency voltage to obtain N single-phase non-power frequency voltages with a frequency equal to the target frequency.

[0058] The output-side transformer 3, which is connected to the parallel output terminals of N frequency conversion and voltage transformation modules 2, is used to transform the single-phase non-power frequency voltage obtained by paralleling N single-phase non-power frequency voltages to obtain a single-phase non-power frequency voltage with an output voltage equal to the target voltage, so as to supply power to the train under the non-power frequency AC power supply system.

[0059] Specifically, the single-phase traction power supply frequency converter of this application includes an input-side transformer 1 (power frequency transformer), N frequency conversion transformer modules 2, and an output-side transformer 3 (non-power frequency transformer). Its working principle is as follows:

[0060] The input terminal of input transformer 1 receives a power frequency voltage (U1 / 50Hz). After receiving the power frequency voltage, input transformer 1 transforms the power frequency voltage to obtain at least one single-phase power frequency voltage (U2 / 50Hz). Assuming that input transformer 1 has N output terminals, and each of the N output terminals outputs one single-phase power frequency voltage, then input transformer 1 outputs N single-phase power frequency voltages.

[0061] Any single-phase power frequency voltage output from the input-side transformer 1 can supply power to one frequency converter module 2. Thus, the N output terminals of the input-side transformer 1 are connected one by one to N frequency converter modules 2. The operating state of each frequency converter module 2 is the same. Specifically, after each frequency converter module 2 receives a single-phase power frequency voltage, it performs frequency conversion and voltage conversion processing on the input single-phase power frequency voltage according to the frequency conversion and voltage conversion requirements of the frequency converter module, thereby obtaining N single-phase non-power frequency voltages (U3 / non-50Hz) with a frequency equal to the target frequency.

[0062] The output terminals of N frequency converter and transformer modules 2 are connected in parallel to the input terminal of the output transformer 3. The input terminal of the output transformer 3 receives the single-phase non-power frequency voltage obtained by connecting N single-phase non-power frequency voltages from the N frequency converter and transformer modules 2 in parallel. After receiving the parallel single-phase non-power frequency voltage, the output transformer 3 transforms the voltage to obtain a single-phase non-power frequency voltage (U4 / non-50Hz) with an output voltage equal to the target voltage, thus enabling power supply to the train under a non-power frequency AC power supply system.

[0063] This invention provides a single-phase traction power supply frequency converter, comprising an input-side transformer, N frequency conversion and voltage transformation modules, and an output-side transformer. The input-side transformer transforms the power frequency voltage to obtain N single-phase power frequency voltages. Each frequency conversion and voltage transformation module transforms one input single-phase power frequency voltage to obtain N single-phase non-power frequency voltages with frequencies equal to the target frequency. The output-side transformer transforms the single-phase non-power frequency voltage obtained by connecting the N parallel single-phase non-power frequency voltages to obtain a single-phase non-power frequency voltage with an output voltage equal to the target voltage, thus supplying power to trains under non-power frequency AC power supply systems. Therefore, this application can convert the power supply of domestic power frequency AC power supply systems into a single-phase non-power frequency AC power supply, thereby enabling commissioning tests of EMUs and electric locomotives to be exported under foreign non-power frequency power supply systems, improving the safety and reliability of exported EMUs and electric locomotives. Furthermore, the device of this application can be applied to frequency conversion operations using foreign power frequency voltages.

[0064] Based on the above embodiments:

[0065] Please refer to Figure 2 , Figure 2This is a schematic diagram of the structure of a frequency converter and voltage converter module provided in an embodiment of the present invention.

[0066] As an optional embodiment, the frequency converter module 2 includes a first connector 21, a single-phase AC-DC-AC converter 22, and a second connector 23; wherein:

[0067] The first end of the first connector 21 is connected to one output terminal of the input-side transformer 1, the second end of the first connector 21 is connected to the first AC side of the single-phase AC-DC-AC converter 22, the second AC side of the single-phase AC-DC-AC converter 22 is connected to the first end of the second connector 23, and the second end of the second connector 23 is connected to the input terminal of the output-side transformer 3; wherein, the first connector 21 and the second connector 23 are used to isolate the connection lines between the single-phase AC-DC-AC converter 22 and the input-output-side transformers.

[0068] Specifically, each of the N frequency converter and transformer modules 2 in this application includes a first connector 21, a single-phase AC-DC-AC converter 22, and a second connector 23, and its working principle is as follows:

[0069] The frequency converter module 2 uses a single-phase AC-DC-AC converter 22 to convert and transform the input single-phase power frequency voltage to obtain a single-phase non-power frequency voltage with adjustable voltage amplitude and frequency. Meanwhile, to ensure the reliable operation of the single-phase AC-DC-AC converter 22, connectors are provided between the input-side transformer 1 and the single-phase AC-DC-AC converter 22, and between the single-phase AC-DC-AC converter 22 and the output-side transformer 3. These connectors isolate the connection lines between the single-phase AC-DC-AC converter 22 and the input-side transformer 1 and the output-side transformer 3, thereby ensuring the reliable operation of the single-phase AC-DC-AC converter 22.

[0070] More specifically, the single-phase AC-DC-AC converter 22 of this application can be made by connecting two single-phase H-bridge converters on the common DC side to realize AC-DC-AC power conversion.

[0071] As an optional embodiment, the first connector 21 and the second connector 23 are specifically reactors, filters, disconnect switches, or transformers.

[0072] Specifically, the first connector 21 and the second connector 23 of this application may be selected from, but are not limited to, reactors, filters, disconnect switches or transformers, and this application does not make any special limitations here.

[0073] It should be noted that the first connector 21 and the second connector 23 are devices that isolate the connection lines between the single-phase AC-DC-AC converter 22 and the input transformer 1 and the output transformer 3. If they affect the operation of the single-phase AC-DC-AC converter 22, the influence of the first connector 21 and the second connector 23 must be considered when controlling the operating state of the single-phase AC-DC-AC converter 22, so as to ensure that the overall operating state of the frequency converter and transformer module 2 is not affected.

[0074] As an alternative embodiment, the filter is specifically an LC filter, an RC filter, or an LCL filter.

[0075] Specifically, the filter in this application may be, but is not limited to, an LC filter (a filter circuit designed using a combination of inductors and capacitors), an RC filter (a filter circuit designed using a combination of resistors and capacitors), or an LCL filter (a third-order resonant circuit designed using a combination of inductors and capacitors). This application does not impose any particular limitation on these filters.

[0076] As an optional embodiment, the single-phase AC-DC-AC converter 22 is specifically a converter with a two-level or three-level or MMC or cascaded topology constructed using power switching devices.

[0077] Specifically, the single-phase AC-DC-AC converter 22 of this application can be a two-level converter composed of power switching devices, that is, the driving level of the power switching devices in the converter includes both high and low levels; it can also be a three-level converter composed of power switching devices, that is, the driving level of the power switching devices in the converter includes high, low, and zero levels; or it can be a multi-level converter composed of power switching devices (such as an MMC (Modular Multilevel Converter) converter or a cascaded converter), that is, the driving level of the power switching devices in the converter includes multiple high levels, multiple low levels, and zero levels. This application does not impose any particular limitation on which type of converter is selected.

[0078] As an alternative embodiment, the power switching device is specifically a GTO, an IGBT, or a SiC.

[0079] Specifically, the power switching device of this application may be a GTO (Gate Turn-off Thyristor), which is suitable for high-power applications; or an IGBT (Insulated Gate Bipolar Transistor), which has high switching speed, low switching loss, and the ability to withstand pulse current surges; or SiC (Silicon Carbide Power Switching Device), which has low on-resistance and high voltage withstand capability. This application does not impose any particular limitation on the specific power switching device to be selected.

[0080] As an optional embodiment, when the input side of the single-phase traction power supply frequency converter is connected to a three-phase power frequency voltage, the input side transformer 1 is specifically as follows:

[0081] A three-phase transformer is used to transform three-phase power frequency voltages to obtain three single-phase power frequency voltages: phase A, phase B, and phase C.

[0082] Specifically, when the input side of the single-phase traction power supply frequency converter is connected to a three-phase power frequency voltage, the input-side transformer 1 of this application is a three-phase transformer, such as... Figure 3 As shown, after receiving a three-phase power frequency voltage, the three-phase transformer transforms the three-phase power frequency voltage to obtain three single-phase power frequency voltages: phase A, phase B, and phase C. Correspondingly, phase A, phase B, and phase C power frequency voltages supply power to the three frequency converter modules: phase A, phase B, and phase C, respectively.

[0083] As an optional embodiment, when a single-phase power frequency voltage is connected to the input side of the single-phase traction power supply frequency converter, the input side transformer 1 is specifically as follows:

[0084] A single-phase transformer is used to transform the input single-phase power frequency voltage to obtain one single-phase power frequency voltage, and then divide the one single-phase power frequency voltage into N outputs.

[0085] Specifically, when a single-phase power frequency voltage is connected to the input side of the single-phase traction power supply frequency converter, the input-side transformer 1 of this application is a single-phase transformer, such as... Figure 4 As shown, after receiving a single-phase power frequency voltage, the single-phase transformer transforms the input single-phase power frequency voltage to obtain one single-phase power frequency voltage. This single single-phase power frequency voltage can then be divided into N outputs, resulting in N single-phase power frequency voltages. Correspondingly, the N single-phase power frequency voltages supply power to N frequency conversion and voltage transformation modules.

[0086] As an optional embodiment, the input-side transformer 1 and the output-side transformer 3 are specifically oil-immersed transformers, dry-type transformers, isolation transformers, or multi-winding transformers.

[0087] Specifically, the input-side transformer 1 and the output-side transformer 3 of this application can be selected from, but are not limited to, oil-immersed transformers, dry-type transformers, isolation transformers, or multi-winding transformers. This application does not impose any special limitations on them.

[0088] As an optional embodiment, the target frequency is specifically 60Hz or

[0089] Specifically, the non-power frequency power supply systems for foreign railways are mainly divided into 25kV / 60Hz and There are two types, so this application can specifically control the output of the frequency converter module to 60Hz or... Frequency power supply (reference) Figure 5 ).

[0090] As an optional embodiment, the single-phase traction power supply frequency converter also includes:

[0091] The controller, which is connected to N frequency converter modules, is used to pre-select the input-side transformer and output-side transformer connected to the N frequency converter modules according to a preset transformer selection strategy, for reference in the device connection design. When the N frequency converter modules are operating, the controller controls the frequency converter operation of the N frequency converter modules according to the output voltage of the input-side transformer and the input demand voltage of the output-side transformer, so that the input voltage of the output-side transformer meets its input demand voltage.

[0092] Furthermore, the single-phase traction power supply frequency converter of this application also includes a controller for controlling each frequency converter module by controlling the on / off state of the power switching devices within each frequency converter module. Its working principle is as follows:

[0093] Considering that the output voltage of the input-side transformer must be within the allowable input range of the frequency converter module when transforming the power frequency voltage connected to the device's input side, and that the output voltage of the output-side transformer must meet the train's power supply requirements when transforming the single-phase non-power frequency voltage output from the parallel frequency converter modules, this application pre-sets a transformer selection strategy for selecting the input-side and output-side transformers within the device. Based on this, the controller pre-selects the input-side and output-side transformers connected to the N frequency converter modules according to the preset transformer selection strategy, for reference in the device connection design. After the device is connected and put into operation, the controller controls the frequency conversion and transformation operation of the N frequency converter modules according to the output voltage of the input-side transformer and the input requirement voltage of the output-side transformer, with the aim of ensuring that the input voltage of the output-side transformer meets its input requirement voltage, thereby ultimately providing the power supply voltage required by the train.

[0094] As an optional embodiment, when selecting the input-side transformer and the output-side transformer, the controller is specifically used to:

[0095] The required input and output voltages of the frequency converter and transformer module are determined based on the allowable input and output ranges of the module.

[0096] The input voltage requirements of the input transformer are determined based on the input voltage requirements of the frequency converter and the power frequency voltage pre-connected to the input side of the device.

[0097] Based on the input voltage conditions, a transformer combination that meets the input voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the input-side transformer.

[0098] The output voltage of the output transformer is determined based on the output voltage requirements of the frequency converter and the power supply voltage requirements of the train.

[0099] Based on the output voltage conditions, a transformer combination that meets the output voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the output side transformer.

[0100] Specifically, when selecting the input-side transformer and the output-side transformer, the controller first finds an input voltage of the frequency converter within the allowable input range of the frequency converter module as the input demand voltage of the frequency converter module, and finds an output voltage of the frequency converter module within the allowable output range of the frequency converter module as the output demand voltage of the frequency converter module.

[0101] It is known that the input-side transformer transforms the power frequency voltage connected to the device's input side, resulting in the input voltage of the frequency converter module. Therefore, the controller can determine the input transformation condition of the input-side transformer based on the input voltage requirement of the frequency converter module and the power frequency voltage pre-connected to the device's input side. Then, based on the input transformation condition of the input-side transformer, a transformer is selected from a preset transformer cluster. The purpose is to combine the selected transformers into a transformer combination that meets the input transformation condition. This transformer combination can then be used as the input-side transformer and connected to the device.

[0102] Similarly, it is known that the output-side transformer transforms the single-phase non-power frequency voltage output in parallel from each frequency converter and transformer module to obtain the train's power supply voltage. Therefore, the controller can determine the output transformation condition of the output-side transformer based on the output voltage requirements of the frequency converter and transformer module and the power supply voltage requirements of the train. Then, based on the output transformation condition of the output-side transformer, a transformer is selected from the preset transformer cluster. The purpose is to combine the selected transformers into a transformer combination that meets the output transformation condition. This transformer combination can then be used as the output-side transformer and connected to the device.

[0103] As an optional embodiment, the controller is also used for:

[0104] Obtain the actual single-phase non-power frequency voltage output by the transformer on the output side, and calculate the voltage error between the train's power supply demand voltage and the actual single-phase non-power frequency voltage.

[0105] The frequency conversion and voltage conversion operation of the frequency conversion and voltage conversion module is adjusted accordingly based on the voltage error, so that the actual single-phase non-power frequency voltage meets the power supply requirements of the train.

[0106] Furthermore, considering that there may be some error between the actual single-phase non-power frequency voltage output by the output transformer and the power supply demand voltage of the train, the controller can also calculate the voltage error between the power supply demand voltage of the train and the actual single-phase non-power frequency voltage output by the output transformer after obtaining the actual single-phase non-power frequency voltage output by the output transformer. Then, the frequency conversion and voltage conversion operation of the frequency conversion and voltage conversion module is adjusted accordingly based on the voltage error between the two, so that the actual single-phase non-power frequency voltage output by the output transformer meets the power supply demand voltage of the train.

[0107] This application also provides a single-phase traction power supply frequency conversion method, applicable to any of the above-mentioned single-phase traction power supply frequency conversion power devices, the single-phase traction power supply frequency conversion method comprising:

[0108] The input-side transformer and output-side transformer connected to the N frequency converter and transformer modules are selected in advance according to the preset transformer selection strategy for reference in the device connection design.

[0109] When N frequency converter and voltage converter modules are operating, the frequency converter and voltage converter operation of the N frequency converter and voltage converter modules are controlled according to the output voltage of the input transformer and the input demand voltage of the output transformer, so that the input voltage of the output transformer meets its input demand voltage.

[0110] As an optional embodiment, the process of pre-selecting the input-side transformer and output-side transformer connected to the N frequency converter modules according to a preset transformer selection strategy includes:

[0111] The required input and output voltages of the frequency converter and transformer module are determined based on the allowable input and output ranges of the module.

[0112] The input voltage requirements of the input transformer are determined based on the input voltage requirements of the frequency converter and the power frequency voltage pre-connected to the input side of the device.

[0113] Based on the input voltage conditions, a transformer combination that meets the input voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the input-side transformer.

[0114] The output voltage of the output transformer is determined based on the output voltage requirements of the frequency converter and the power supply voltage requirements of the train.

[0115] Based on the output voltage conditions, a transformer combination that meets the output voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the output side transformer.

[0116] As an optional embodiment, the single-phase traction power supply frequency conversion method further includes:

[0117] Obtain the actual single-phase non-power frequency voltage output by the transformer on the output side, and calculate the voltage error between the train's power supply demand voltage and the actual single-phase non-power frequency voltage.

[0118] The frequency conversion and voltage conversion operation of the frequency conversion and voltage conversion module is adjusted accordingly based on the voltage error, so that the actual single-phase non-power frequency voltage meets the power supply requirements of the train.

[0119] For a description of the frequency conversion method provided in this application, please refer to the above-described embodiments of the frequency conversion power supply device; further details will not be repeated here.

[0120] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0121] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A single-phase traction power supply variable frequency power supply device, characterized by, include: An input-side transformer for inputting power frequency voltage is used to transform the power frequency voltage to obtain N single-phase power frequency voltages; where N is a positive integer; N frequency conversion and voltage transformation modules are connected one-to-one with the N output terminals of the input-side transformer. Each frequency conversion and voltage transformation module is used to convert the input single-phase power frequency voltage to obtain N single-phase non-power frequency voltages with a frequency equal to the target frequency. The output-side transformer, which is connected to the parallel output terminals of N frequency conversion and voltage conversion modules, is used to transform the single-phase non-power frequency voltage obtained by paralleling N single-phase non-power frequency voltages to obtain a single-phase non-power frequency voltage with an output voltage equal to the target voltage, so as to supply power to the train under the non-power frequency AC power supply system. When the input side of the single-phase traction power supply frequency converter is connected to a three-phase power frequency voltage, the input side transformer is specifically: A three-phase transformer is used to transform the three-phase power frequency voltage to obtain three single-phase power frequency voltages: A-phase power frequency voltage, B-phase power frequency voltage, and C-phase power frequency voltage. Correspondingly, the frequency converter module includes an A-phase frequency converter module, a B-phase frequency converter module, and a C-phase frequency converter module; the A-phase power frequency voltage, the B-phase power frequency voltage, and the C-phase power frequency voltage supply power to the three frequency converter modules respectively. When the input side of the single-phase traction power supply frequency converter is connected to a single-phase power frequency voltage, the input side transformer is specifically: A single-phase transformer is used to transform the input single-phase power frequency voltage to obtain one single-phase power frequency voltage, and then divide the one single-phase power frequency voltage into N outputs to obtain N single-phase power frequency voltages. The single-phase traction power supply frequency converter also includes: A controller, connected to N frequency converter and transformer modules respectively, is used to pre-select the input-side transformer and output-side transformer connected to the N frequency converter and transformer modules according to a preset transformer selection strategy, for reference in device connection design; when the N frequency converter and transformer modules are operating, the controller controls the frequency converter and transformer operation of the N frequency converter and transformer modules according to the output voltage of the input-side transformer and the input demand voltage of the output-side transformer, so that the input voltage of the output-side transformer meets its input demand voltage; When selecting the input-side transformer and the output-side transformer, the controller is specifically used for: The required input voltage and output voltage of the frequency converter module are determined based on the allowable input and output range of the frequency converter module. The input voltage of the input transformer is determined based on the input voltage requirement of the frequency converter and the power frequency voltage pre-connected to the input side of the device. Based on the input voltage conditions, a transformer combination that meets the input voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the input-side transformer. The output voltage of the output-side transformer is determined based on the output voltage requirement of the frequency converter and the power supply voltage requirement of the train. Based on the output voltage conditions, a transformer combination that meets the output voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the output-side transformer. The frequency converter module includes a first connector, a single-phase AC-DC-AC converter, and a second connector; wherein: The first end of the first connector is connected to one output terminal of the input-side transformer, the second end of the first connector is connected to the first AC side of the single-phase AC-DC-AC converter, the second AC side of the single-phase AC-DC-AC converter is connected to the first end of the second connector, and the second end of the second connector is connected to the input terminal of the output-side transformer; wherein, the first connector and the second connector are used to isolate the connection lines between the single-phase AC-DC-AC converter and the input-output-side transformer; The first connector and the second connector are specifically reactors, filters, disconnect switches, or transformers; The filter is specifically an LC filter, an RC filter, or an LCL filter; The target frequency is specifically 60 Hz or 16 Hz; Each frequency converter and voltage transformer module operates in the same state to obtain N single-phase non-power frequency voltages with frequencies equal to the target frequency; The controller is also used for: Obtain the actual single-phase non-power frequency voltage output by the output-side transformer, and calculate the voltage error between the power supply demand voltage of the train and the actual single-phase non-power frequency voltage; The frequency conversion and voltage conversion operation of the frequency conversion and voltage conversion module is adjusted accordingly based on the voltage error, so that the actual single-phase non-power frequency voltage meets the power supply requirements of the train.

2. The single-phase traction power supply frequency conversion power supply device as claimed in claim 1, characterized in that, The single-phase AC-DC-AC converter is specifically a converter with a two-level, three-level, MMC, or cascaded topology constructed using power switching devices.

3. The single-phase traction power supply frequency conversion power supply device as claimed in claim 2, characterized in that, The power switching device is specifically a GTO, IGBT, or SiC.

4. The single-phase traction power supply frequency conversion power supply device as claimed in claim 1, characterized in that, The input-side transformer and the output-side transformer are specifically oil-immersed transformers, dry-type transformers, isolation transformers, or multi-winding transformers.

5. A single-phase traction power supply variable frequency method, characterized by, The single-phase traction power supply frequency converter method, applied to any one of claims 1-4, comprises: The input-side transformer and output-side transformer connected to the N frequency converter and transformer modules are selected in advance according to the preset transformer selection strategy for reference in the device connection design. When N frequency converter and voltage converter modules are operating, the frequency converter and voltage converter operation of the N frequency converter and voltage converter modules is controlled according to the output voltage of the input side transformer and the input demand voltage of the output side transformer, so that the input voltage of the output side transformer meets its input demand voltage. The process of pre-selecting the input-side transformers and output-side transformers connected to N frequency converter modules according to a preset transformer selection strategy includes: The required input voltage and output voltage of the frequency converter module are determined based on the allowable input and output range of the frequency converter module. The input voltage of the input transformer is determined based on the input voltage requirement of the frequency converter and the power frequency voltage pre-connected to the input side of the device. Based on the input voltage conditions, a transformer combination that meets the input voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the input-side transformer. The output voltage of the output-side transformer is determined based on the output voltage requirement of the frequency converter and the power supply voltage requirement of the train. Based on the output voltage conditions, a transformer combination that meets the output voltage conditions is selected from the preset transformer cluster, and this transformer combination is used as the output-side transformer. The single-phase traction power supply frequency conversion method also includes: Obtain the actual single-phase non-power frequency voltage output by the output-side transformer, and calculate the voltage error between the power supply demand voltage of the train and the actual single-phase non-power frequency voltage; The frequency conversion and voltage conversion operation of the frequency conversion and voltage conversion module is adjusted accordingly based on the voltage error, so that the actual single-phase non-power frequency voltage meets the power supply requirements of the train.

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