Through traction power supply system based on two-phase-single-phase isolation and non-isolation hybrid topology

Abstract

The invention discloses a through traction power supply system based on two-phase-single-phase isolation and non-isolation hybrid topologies, and belongs to the technical field of power electronic transformers, the through traction power supply system comprises two single-phase isolation and non-isolation hybrid topologies, each single-phase isolation and non-isolation hybrid topologies comprises an isolation unit and a non-isolation unit which are cascaded, each isolation unit comprises one or more cascaded isolation modules, the isolation module comprises a first rectifier, an isolation type power electronic transformer and a first inverter which are in cascade connection in sequence; the non-isolation unit comprises one or more cascaded non-isolation modules, and each non-isolation module comprises a second rectifier and a second inverter which are cascaded in sequence. Compared with a system adopting transformer isolation, an industrial frequency transformer and part of high-frequency isolation transformers are omitted, a short-circuit path can be blocked based on the isolation module, the topological volume is effectively reduced, the cost is reduced, and compared with a completely non-isolated system, the available vector plane is widened, and the safety and reliability of the system are high.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic transformers, and in particular to a through-type traction power supply system based on a two-phase-single-phase isolated and non-isolated hybrid topology. Background Art

[0002] At present, the main transformer of the traditional out-of-phase traction power supply scheme has a simple structure and low manufacturing cost, but the uncertainty and nonlinearity of the single-phase traction load lead to harmonic, reactive and negative sequence problems in the three-phase power grid, seriously damaging the power quality of the three-phase power grid. The contact bow frequently operates when the phase is over-split, resulting in unstable power supply for the locomotive load and electric arcing, which seriously affects the safety of the electric traction system. The through-type traction power supply system can completely eliminate the over-phase between substations, comprehensively manage the negative sequence, reactive power and harmonic problems of the three-phase power grid, improve the power quality of the power grid, and its output voltage amplitude and phase are fully controllable. In order to realize the through-type traction power supply, a variety of topologies such as three-phase-single-phase and two-phase-single-phase have been proposed, which are mainly divided into three categories:

[0003] ① Such as Figure 1 The input shown is a two-phase-to-single-phase converter isolated by an industrial frequency transformer. The two-phase electricity is reduced to low-voltage two-phase electricity through a high-ratio multi-tap transformer. Both phases of electricity are converted into direct current through n rectifier module converters, and are converted into single-phase alternating current through the subsequent inverter module. The two-phase output is then connected to a single-phase traction network after a total of 2n inverters are cascaded.

[0004] ② If Figure 2 In the non-isolated two-phase to single-phase converter shown, the input high-voltage two-phase electricity is converted into direct current through n rectifier modules respectively, the DC sides of the n rectifiers are directly connected to the n inverters at the next stage, and then 2n inverters are cascaded to output single-phase alternating current connected to the single-phase traction network;

[0005] ③If Figure 3 The isolated three-phase to single-phase converter shown is composed of a single-phase power electronic transformer connected in star shape. Its input is connected to a high-voltage three-phase power grid, and outputs direct current after isolation by a high-frequency DC-DC converter. The alternating current output by the cascaded n inverters of each phase is then connected in parallel, and then the output single-phase alternating current is connected to a single-phase traction network.

[0006] The above three topologies have the following technical features:

[0007] ① The first topology (two-phase to single-phase converter isolated by industrial frequency transformer) uses the existing traction transformer to convert three-phase electricity into two-phase electricity as the input of the two-phase multi-module cascade converter. The output side of the two-phase converter is cascaded to supply power to the traction load. This topology sets a multi-tap industrial frequency transformer on the input side, which reduces the consistency of the multi-module cascade converter.

[0008] ② The second topology (non-isolated two-phase to single-phase converter) eliminates the input multi-tap transformer, which reduces the volume, weight and system of the same-phase power supply system compared to the first topology. However, there is no electrical isolation in the circuit of this topology, and certain switching states may cause the DC side capacitor to short-circuit. It is necessary to select a specific switching state to avoid this short-circuit path, which results in a reduction in the fault tolerance vector in the event of a fault and reduced system reliability.

[0009] ③ The third topology (isolated three-phase to single-phase converter) uses a fully isolated power electronic transformer for each phase. The entire topology uses high-frequency isolated DC-DC to achieve electrical isolation of input and output, and the use of high-frequency isolated DC-DC converters significantly reduces the size and weight of the converter, but it also leads to increased cost control and complexity of the entire system.

[0010] Through comparison, it is found that the system costs of the above three topologies that use industrial frequency transformers or medium and high frequency isolation DC-DC for electrical isolation are relatively high. After completely eliminating the isolation transformer, more DC side capacitor short circuits will occur in the non-isolated circuit, causing serious harm to the safe operation of the entire system. Summary of the invention

[0011] The purpose of the present invention is to overcome the problems of the prior art and provide a through traction power supply system based on a two-phase-single-phase isolated and non-isolated hybrid topology.

[0012] The objective of the present invention is achieved through the following technical solutions: a through-connected traction power supply system based on a two-phase-single-phase isolated non-isolated hybrid topology, the system comprising a first single-phase isolated non-isolated hybrid topology and a second single-phase isolated non-isolated hybrid topology, the input side of the first single-phase isolated non-isolated hybrid topology is connected to a one-phase high-voltage power grid of a three-phase-two-phase traction transformer, the input side of the second single-phase isolated non-isolated hybrid topology is connected to the other-phase high-voltage power grid of the three-phase-two-phase traction transformer, the output sides of the first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology are cascaded and connected to the traction power supply network;

[0013] The first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology both include cascaded isolation units and non-isolated units, the isolation units are arranged at the head end and / or the tail end, and the non-isolated units are arranged at the middle stage; the isolation unit includes one or more cascaded isolation modules, the isolation module includes a first rectifier, an isolated power electronic transformer, and a first inverter cascaded in sequence; the non-isolated unit includes one or more cascaded non-isolated modules, the non-isolated module includes a second rectifier and a second inverter cascaded in sequence.

[0014] In one example, the positive input side of the first single-phase isolated and non-isolated hybrid topology is connected to one-phase high-voltage power grid of the three-phase-two-phase traction transformer via a first inductor, and the positive input side of the second single-phase isolated and non-isolated hybrid topology is connected to the other-phase high-voltage power grid of the three-phase-two-phase traction transformer via a second inductor.

[0015] In one example, the positive output side of the cascaded first single-phase isolated and non-isolated hybrid topology and the second single-phase isolated and non-isolated hybrid topology is connected to the traction grid via a third reactor.

[0016] In one example, a first capacitor is provided between the first rectifier and the isolated power electronic transformer, and a second capacitor is provided between the isolated power electronic transformer and the first inverter.

[0017] In one example, a third capacitor is provided between the second rectifier and the second inverter.

[0018] In one example, the first rectifier, the second rectifier, the first inverter, and the second inverter are full-bridge structures or half-bridge structures.

[0019] In one example, the isolated power electronic transformer is a dual active circuit, including a cascaded input-side rectifier bridge, a transformer, and an output-side rectifier bridge, and the power control of the isolation module includes:

[0020] Calculate the minimum transmission power of the isolation module. The calculation expression of the minimum transmission power P* is:

[0021] P*=(R2 / (R2+2R1)*P

[0022] in =(k / (k+2))*P in );

[0023] Where R1 is the equivalent resistance of the DC side of the non-isolated module load, R2 is the equivalent load of the isolated module; k = R2 / R1, is the proportional factor; P in is the current input power of the system;

[0024] The minimum transmission power of the isolation module is introduced into the control strategy of the isolated power electronic transformer to change the power transmission size.

[0025] It should be further explained that the technical features corresponding to the above examples can be combined or replaced with each other to form a new technical solution.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Compared with the system using transformer isolation, the present invention eliminates the power frequency transformer and part of the high-frequency isolation transformer, can block the short-circuit path based on the isolation module, and effectively reduce the topological volume, significantly reduce the cost, and compared with the completely non-isolated system, broaden the available vector plane, improve the safety and reliability of the system;

[0028] 2. The topology of the present invention is universal and can adjust the active power and reactive power transmission characteristics for any existing two-phase-single-phase traction transformer, thereby meeting the balance conditions of the corresponding traction transformer and achieving the grid-side power factor, thereby improving the grid-side power quality.

[0029] 3 The topology of the present invention has the function of energy recovery and can operate normally in all four quadrants. Energy flows in both directions and energy recovery can be achieved while avoiding the injection of harmonics into the grid side.

[0030] 4. The topology of the present invention is flexible and can control the switching states of the rectifier, inverter and isolated power electronic transformer according to different load characteristics to adjust the output voltage amplitude, phase and frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to represent the same or similar parts. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0032] Figure 1 The schematic diagram of a two-phase to single-phase converter with input isolated by an industrial frequency transformer is shown;

[0033] Figure 2 It is a schematic diagram of a non-isolated two-phase to single-phase converter;

[0034] Figure 3 It is a schematic diagram of an isolated three-phase to single-phase converter;

[0035] Figure 4 A schematic diagram of an n-module isolated and non-isolated hybrid topology provided for an example of the present invention;

[0036] Figure 5 A schematic diagram of a 6-module isolated and non-isolated hybrid topology provided for an example of the present invention;

[0037] Figure 6 A block diagram of the power transmission control principle of an isolation module provided as an example of the present invention. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the use of ordinal numbers (e.g., "first and second", "first to fourth", etc.) is to distinguish objects, and is not limited to this order, and cannot be understood as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In addition, 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.

[0042] In one example, if Figure 1As shown, a through traction power supply system based on a two-phase-single-phase isolated non-isolated hybrid topology includes a first single-phase isolated non-isolated hybrid topology and a second single-phase isolated non-isolated hybrid topology, the input side of the first single-phase isolated non-isolated hybrid topology is connected to a one-phase (α phase) high-voltage grid of a three-phase-two-phase traction transformer, the input side of the second single-phase isolated non-isolated hybrid topology is connected to another phase (β phase) high-voltage grid of a three-phase-two-phase traction transformer, and the output sides of the first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology are cascaded and connected to the traction power supply grid, thereby forming a two-phase-single-phase isolated non-isolated hybrid topology. Preferably, the positive input side of the first single-phase isolated non-isolated hybrid topology is connected to a one-phase high-voltage grid of a three-phase-two-phase traction transformer via a first reactor, the positive input side of the second single-phase isolated non-isolated hybrid topology is connected to another phase high-voltage grid of a three-phase-two-phase traction transformer via a second reactor, and the positive output side of the cascaded first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology is connected to the traction grid via a third reactor.

[0043] Furthermore, the first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology both include cascaded isolation units and non-isolated units, the isolation units are arranged at the head end and / or the tail end, preferably the isolation units are arranged at the head end and the tail end, and the non-isolated units are arranged at the middle stage, and preferably the circuit structures of the first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology are the same. The isolation unit includes a plurality of cascaded isolation modules, the isolation module includes a first rectifier, an isolated power electronic transformer, and a first inverter that are cascaded in sequence, a first capacitor is preferably provided between the first rectifier and the isolated power electronic transformer, a second capacitor is preferably provided between the isolated power electronic transformer and the first inverter, a plurality of first rectifiers are cascaded on the input side, and a plurality of first inverters are cascaded on the output side. The non-isolated unit includes a plurality of non-isolated modules, and the non-isolated module includes a second rectifier and a second inverter cascaded in sequence, and a third capacitor is preferably provided between the second rectifier and the second inverter, and a plurality of second rectifiers are cascaded on the input side, and a plurality of second inverters are cascaded on the output side to realize the cascade of the non-isolated module; further, a plurality of first rectifiers and second rectifiers are cascaded on the input side, and a plurality of first inverters and second inverters are cascaded on the output side to realize the cascade connection between the isolation unit and the non-isolated unit. In this example, the first rectifier and the second rectifier are single-phase single-module rectifiers, the first inverter and the second inverter are single-phase inverters, and the isolated power electronic transformer is a single-phase single-module isolated power electronic transformer. Preferably, the isolated power electronic transformer is a dual active circuit, including a sequentially cascaded input side rectifier bridge, a transformer, and an output side rectifier bridge, and the input side rectifier bridge and the output side rectifier bridge are preferably full-bridge circuits composed of transistors. By combining the dual active circuit with the second rectifier and the second inverter in the non-isolated module, energy can flow in any direction between the source and the load, with four-quadrant operating characteristics.

[0044] The front-stage input port of the two-phase-single-phase isolated non-isolated hybrid topology is composed of two single-phase isolated non-isolated hybrid power electronic transformers (the first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology) input port leads, and the rear-stage output port is composed of two single-phase isolated non-isolated hybrid power electronic transformer output ports connected in series. Take the single-phase isolated non-isolated hybrid topology structure with isolation modules at the head and tail ends as an example for explanation. This example includes 3 isolation modules located at the head and tail ends and n-3 non-isolated modules located at the middle stage, such as Figure 4 As shown, input single-phase power u α The positive end is connected to the positive end AP1 of the first module input port of the α phase through the reactor L1, and the negative end AN1 of the first module input port is connected to the positive end AP2 of the second module input port. The connection mode of the third to n modules is similar. The negative end ANn of the input port of the nth module is connected to the negative end of the α phase output of the Vv traction transformer. β The positive end is connected to the positive end BP1 of the input port of the first module of the β phase through the inductor L2, the negative end BN1 of the input port of the first module is connected to the positive end BP2 of the input port of the second module, and the connection method of the third to n modules is similar. The negative end BNn of the input port of the nth module is connected to the negative end of the β phase output of the Vv traction transformer.

[0045] The first module, the n-1th module, and the nth module in the α and β phases are all isolated modules, and the two ends of their DC capacitors are connected to the intermediate high-frequency isolated DC-DC converter (isolated power electronic transformer); the second to n-2 modules are all non-isolated modules, and their output capacitors are directly connected to the subsequent single-phase inverter. The k phase is the output phase, which is composed of n subsequent inverters of the α phase and n subsequent inverters of the β phase in cascade. The positive end of the k phase output port is the positive end CP1 of the output port of the subsequent inverter of the first module of the α phase, and CP1 is connected to the positive end of the traction network. The negative end of the output port is the negative end CN2n of the output port of the subsequent inverter of the nth module of the β phase, and CN2n is connected to the negative end of the traction network. The negative terminal CN1 of the output port of the first module of phase k is connected to the positive terminal CP2 of the output port of the rear-stage inverter of the second module of phase k, the negative terminal CN2 of the output port of the rear-stage inverter of the second module of phase k is connected to the positive terminal CP3 of the output port of the rear-stage inverter of the third module of phase k, and the connection method of the 3rd to 2n modules of phase k is similar.

[0046] Furthermore, according to the different balancing conditions for achieving grid-side current power factor by different traction transformers, each phase topology of the topology (the first single-phase isolated and non-isolated hybrid topology, the second single-phase isolated and non-isolated hybrid topology) can be a 6-module cascade converter with isolation modules at both ends, or a 6-module cascade converter with 2 modules at the head end and 1 module at the tail end as an isolation module, or other combinations of isolation and non-isolation modules.

[0047] Furthermore, a two-phase-single-phase traction power supply system based on a head-to-tail isolated single-phase-single-phase 6-module cascade isolation non-isolation hybrid topology is described. The specific topology connection form is as follows: Figure 5 As shown, it includes two isolation modules respectively arranged at the head and tail ends and four non-isolation modules arranged at the middle stage, and the input single-phase power u α The positive end is connected to the positive end AP1 of the input port of the first module of the α phase through the reactor L1, and the negative end AN1 of the input port of the first module is connected to the positive end AP2 of the input port of the second module. The connection mode of the third to sixth modules is similar, and finally the negative end ANn of the input port of the sixth module is connected to the negative end of the α phase output of the Vv traction transformer. β The positive end is connected to the positive end BP1 of the input port of the first module of the β phase through the reactor L2, the negative end BN1 of the input port of the first module is connected to the positive end BP2 of the input port of the second module, and the connection mode of the 3rd to 6th modules is similar. Finally, the negative end BNn of the input port of the 6th module is connected to the negative end of the β phase output of the Vv traction transformer. Among them, the first module and the sixth module in the α and β phases are isolation modules, and the second to fourth modules are non-isolation modules. The k phase is the output phase, which is composed of 6 α-phase rear-stage inverters and 6 β-phase rear-stage inverters, a total of 12 inverter modules cascaded. The positive end of the k-phase output port is the positive end CP1 of the rear-stage inverter output port of the first module of the α phase, and CP1 is connected to the positive end of the traction network. The negative end of the output port is the negative end CN12 of the rear-stage inverter output port of the sixth module of the β phase, and CN12 is connected to the negative end of the traction network. The negative terminal CN1 of the output port of the first module of phase k is connected to the positive terminal CP2 of the output port of the rear-stage inverter of the second module of phase k, the negative terminal CN2 of the output port of the rear-stage inverter of the second module of phase k is connected to the positive terminal CP3 of the output port of the rear-stage inverter of the third module of phase k, and the connection method of the 3rd to 12th modules of phase k is similar.

[0048] The number n of isolated modules and non-isolated modules in two single-phase isolated non-isolated hybrid topologies is related to factors such as the internal topology structure and the withstand voltage of the switch tube. The internal topology structure can be a three-level full bridge, a three-level half bridge, or a two-level full bridge, a two-level half bridge, and the withstand voltage level of the switch tube is determined according to actual needs. If a three-level structure and a switch tube with a high withstand voltage level are used, the number of modules of the converter cascade is relatively small. The present invention combines an isolated converter and a non-isolated converter to propose a two-phase-single-phase isolated non-isolated hybrid topology for a through traction power supply system, which achieves power balance of the traction transformer on the basis of reducing the number of power conversion stages and reducing the cost of the converter, and has good power quality on the grid side and high system reliability.

[0049] In the traction power supply system formed by the isolation module and the non-isolation module of the present invention, the power of the non-isolation module is generally controlled, that is, the control module sends a PWM signal to control the switching of the rectifier and the inverter in the non-isolation module, but does not directly control the transmission power of the isolation module, which will cause the high-frequency transformer of the isolated power electronic transformer to be designed according to the maximum transmission power of the system when designing the capacity, which greatly increases the volume of the transformer. Based on the above traction power supply system, the present invention further controls the power of the isolation module, including:

[0050] Calculate the minimum transmission power of the isolation module. The calculation expression of the minimum transmission power P* is:

[0051] P*=(R2 / (R2+2R1)*P in =(k / (k+2))*P in );

[0052] Where R1 is the equivalent resistance of the DC side of the non-isolated module load, R2 is the equivalent load of the isolated module; k = R2 / R1, is the proportional factor; P in is the current input power of the system;

[0053] The minimum transmission power of the isolation module is introduced into the control strategy of the isolated power electronic transformer to change the power transmission size.

[0054] At this time, the derivation process of the calculation expression of the minimum transmission power P* is as follows:

[0055] Step 1: Calculate the current input power P of the system in :

[0056] P in =V s ×I s ;

[0057] Among them, V s is the input AC voltage of the system, I s Input AC current.

[0058] Step 2: Solve the modulation index m of the system:

[0059]

[0060] Among them, θ * It is the DC voltage reference value sent by the host computer.

[0061] Step 3. Solve the voltage balancing boundary of the system. When the voltage balancing boundary is reached, the converter with large load power (heavy-load module, non-isolated module in this example) tends to choose the vector that can transmit the maximum power, so the port level is 2E or -2E most of the time, ignoring the 0 and ±E vectors in the vector transfer path. The essence of the voltage balancing boundary is the maximum power transmitted by the converter at ±2E. When calculating the load ratio, it can be considered as the difference between the power transmitted by the 2E level converter and the power transmitted by the normal load converter, assuming that the port level of the heavy-load module is always 2E, and the port level of the light-load module (isolated module in this example) is 6msinωt-4E. In the stable state, the power transmitted by the converter is equal within half a cycle, so only the power difference in the first half of the entire cycle can be calculated, and the unbalanced load and input current satisfy the following relationship:

[0062]

[0063] Where ω represents the angular frequency; t represents the time; E represents the minimum voltage change unit; R1 is the equivalent resistance of the DC side of the heavy-load module load, and R2 is the equivalent load of the light-load module. Ignoring the energy stored in the inductor, the input and output power meet V s I s / 2=(2E) 2 Substituting (1 / R2+2 / R1) into the relationship between unbalanced load and input current, we get:

[0064]

[0065] Integrating the above equation, we can get the relationship between unbalanced load and modulation index:

[0066]

[0067] Define the proportional factor k = R2 / R1, and the pressure-equalizing boundary k expression is:

[0068]

[0069] According to the voltage-sharing boundary, the minimum transmission power P* of the isolation module is:

[0070] P*=(R2 / (R2+2R1)*P in =(k / (k+2))*P in ).

[0071] Preferably, if Figure 6 As shown in FIG. 1 , the minimum transmission power of the isolation module is introduced into the control strategy of the isolated power electronic transformer, including:

[0072] (1) According to the actual power P dc-dcThe compensation power △P* generated by the PI controller is used to calculate the synthetic given power P0*; wherein the compensation power △P* is calculated by the PI controller based on the error between the actual output DC voltage U2 of the secondary side of the isolation module and the expected output voltage U2*.

[0073] (2) Calculate the given duty cycle based on the synthesized given power P0* and the DC voltage of the isolated power electronic transformer in the isolation module When the system output reaches a steady state, the given duty cycle and the actual duty cycle Consistent, get the actual duty cycle

[0074]

[0075] in, The PWM given duty cycle of the switch devices in the input side rectifier bridge of the isolated power electronic transformer; The PWM given duty cycle of the switching devices in the output side rectifier bridge of the isolated power electronic transformer; It represents the phase shift duty ratio between the primary and secondary sides of the isolated power electronic transformer; U1 is the primary DC voltage of the isolated power electronic transformer; r is the voltage gain nU2 / U1 of the isolated power electronic transformer, n is the transformation ratio of the isolated power electronic transformer, U2 is the output DC voltage of the secondary side of the isolated power electronic transformer; L is the equivalent inductance of the isolated power electronic transformer; T s In order to ensure the real-time minimum power of the isolation module, r needs to be calculated using the real-time voltage.

[0076] (3) The actual duty cycle The input modulation module obtains the switching signal, and controls the switching of the isolated power electronic transformer in the isolation module based on the switching signal, thereby realizing the transmission power control of the isolation module and achieving the voltage balancing effect. By reducing the power transmission of the isolation module, the volume of the system is reduced and the efficiency is improved.

[0077] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A through-type traction power supply system based on a two-phase-single-phase isolated non-isolated hybrid topology, characterized in that: It includes a first single-phase isolated non-isolated hybrid topology and a second single-phase isolated non-isolated hybrid topology, the input side of the first single-phase isolated non-isolated hybrid topology is connected to a one-phase high-voltage power grid of a three-phase-two-phase traction transformer, the input side of the second single-phase isolated non-isolated hybrid topology is connected to the other-phase high-voltage power grid of the three-phase-two-phase traction transformer, and the output sides of the first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology are cascaded and connected to the traction power supply network; The first single-phase isolated non-isolated hybrid topology and the second single-phase isolated non-isolated hybrid topology both include cascaded isolation units and non-isolated units, the isolation units are arranged at the head end and / or the tail end, and the non-isolated units are arranged at the middle stage; the isolation unit includes one or more cascaded isolation modules, and the isolation module includes a first rectifier, an isolated power electronic transformer, and a first inverter that are cascaded in sequence; The non-isolated unit includes one or more cascaded non-isolated modules, and the non-isolated module includes a second rectifier and a second inverter which are cascaded in sequence.

2. The through-type traction power supply system based on the two-phase-single-phase isolated non-isolated hybrid topology according to claim 1 is characterized in that: The positive input side of the first single-phase isolated and non-isolated hybrid topology is connected to one-phase high-voltage power grid of the three-phase-two-phase traction transformer via a first inductor, and the positive input side of the second single-phase isolated and non-isolated hybrid topology is connected to the other-phase high-voltage power grid of the three-phase-two-phase traction transformer via a second inductor.

3. The through-type traction power supply system based on the two-phase-single-phase isolated non-isolated hybrid topology according to claim 1 is characterized in that: The positive output sides of the cascaded first single-phase isolated and non-isolated hybrid topology and the second single-phase isolated and non-isolated hybrid topology are connected to the traction grid via the third reactor.

4. The through-type traction power supply system based on the two-phase-single-phase isolated non-isolated hybrid topology according to claim 1 is characterized in that: A first capacitor is provided between the first rectifier and the isolated power electronic transformer, and a second capacitor is provided between the isolated power electronic transformer and the first inverter.

5. The through-type traction power supply system based on two-phase-single-phase isolated non-isolated hybrid topology according to claim 1 is characterized in that: A third capacitor is provided between the second rectifier and the second inverter.

6. The through-type traction power supply system based on two-phase-single-phase isolated and non-isolated hybrid topology according to claim 1 is characterized in that: The first rectifier, the second rectifier, the first inverter, and the second inverter are full-bridge structures or half-bridge structures.

7. The through-type traction power supply system based on two-phase-single-phase isolated and non-isolated hybrid topology according to claim 1 is characterized in that: The isolated power electronic transformer is a dual active circuit, including a cascaded input-side rectifier bridge, a transformer, and an output-side rectifier bridge. The power control of the isolation module includes: Calculate the minimum transmission power of the isolation module. The calculation expression of the minimum transmission power P* is: P*=(R2 / (R2+2R1)*P in =(k / (k+2))*P in ); Where R1 is the equivalent resistance of the DC side of the non-isolated module load, R2 is the equivalent load of the isolated module; k = R2 / R1, is the proportional factor; P in is the current input power of the system; The minimum transmission power of the isolation module is introduced into the control strategy of the isolated power electronic transformer to change the power transmission size.

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