阅读说明：本技术 一种机车牵引变压器及其应用 (Locomotive traction transformer and application thereof ) 是由 李艳平 刘毅红 盛政彬 陈立 向坤 曾明成 黄江瑞 冯厉鹏 张志鹏 许晓雷 于 2019-10-28 设计创作，主要内容包括：本发明公开了一种机车牵引变压器及其应用,机车牵引变压器由三个单相变压器组合形成三相变压器,三个所述单相变压器的原边线圈连接至两个逆变模块的不同输出相,且同一单相变压器的原边线圈的两端分别连接两个逆变模块的同一输出相；各所述单相变压器的副边线圈的一端形成三相变压器的输出端,各所述单相变压器的副边线圈的另一端相互连接并接地；各所述单相变压器的原边线圈的中性点与副边线圈的一端通过第一开关连接,各所述单相变压器的副边线圈上设有多个连接开关,用于在接通时形成不同匝数的副边线圈。本发明具有结构简单、操作简便、功能丰富、抑制环流、可适用不同工况等优点。(The invention discloses a locomotive traction transformer and application thereof, wherein the locomotive traction transformer is a three-phase transformer formed by combining three single-phase transformers, primary coils of the three single-phase transformers are connected to different output phases of two inversion modules, and two ends of the primary coil of the same single-phase transformer are respectively connected with the same output phase of the two inversion modules; one end of the secondary coil of each single-phase transformer forms the output end of the three-phase transformer, and the other end of the secondary coil of each single-phase transformer is connected with each other and grounded; the neutral point of the primary coil of each single-phase transformer is connected with one end of the secondary coil through a first switch, and the secondary coil of each single-phase transformer is provided with a plurality of connecting switches for forming secondary coils with different turns when the secondary coils are switched on. The invention has the advantages of simple structure, simple and convenient operation, rich functions, circulation inhibition, suitability for different working conditions and the like.)

1. A locomotive traction transformer is characterized in that the locomotive traction transformer is a three-phase transformer formed by combining three single-phase transformers, primary coils of the three single-phase transformers are connected to different output phases of two inversion modules, and two ends of the primary coil of the same single-phase transformer are respectively connected with the same output phase of the two inversion modules; one end of the secondary coil of each single-phase transformer forms the output end of the three-phase transformer, and the other end of the secondary coil of each single-phase transformer is connected with each other and grounded; the neutral point of the primary coil of each single-phase transformer is connected with one end of the secondary coil through a first switch, and the secondary coil of each single-phase transformer is provided with a plurality of connecting switches for forming secondary coils with different turns when the secondary coils are switched on.

2. The locomotive traction transformer according to claim 1, wherein the number of the connection switches is 2-5.

3. The locomotive traction transformer according to claim 1 or 2, wherein the three-phase transformer is a dry transformer or a flooded transformer.

4. A locomotive traction system comprises a rectification module, an intermediate direct current loop and a plurality of inversion modules which are connected in sequence, and is characterized by further comprising a locomotive traction transformer according to claim 1, 2 or 3, wherein the input end of a three-phase transformer in the locomotive traction transformer is respectively connected with the output end of each inversion module.

5. Method for applying a locomotive traction transformer in a locomotive traction system according to claim 1, 2 or 3,

in the starting stage of the locomotive, a first switch in each single-phase transformer is closed, a neutral point of a primary coil is connected with one end of a secondary coil through the first switch, meanwhile, each connecting switch is disconnected, so that the secondary side of the single-phase transformer is open-circuited, current directly supplies power to a load through the primary coil, and the three-phase transformer is in a working condition of a reactor;

when the locomotive normally runs, the first switch in each single-phase transformer is disconnected, the neutral point of the primary coil is disconnected with one end of the secondary coil, meanwhile, one of the connecting switches is closed, and the three-phase transformer is in the working condition of the transformer.

6. The application method of claim 5, wherein in the normal driving stage of the locomotive, when acceleration is needed, the number of turns of the secondary winding is increased by switching the connection switch, so that the output voltage of the three-phase transformer is increased, and the output power is increased; when speed reduction is needed, the number of turns of the secondary side coil is reduced by switching the connecting switch, so that the output voltage of the three-phase transformer is reduced, and the output power is reduced.

7. The application method according to claim 5, wherein each connection switch corresponds to the output current frequency of the transformer, and the corresponding connection switch is switched when the corresponding preset current frequency is reached.

8. The application method of claim 7, wherein the number of the connection switches is 3, and the connection switches are k2, k3 and k4, wherein the number of turns of the corresponding secondary side coils is reduced sequentially when k2, k3 and k4 are turned on.

9. The application method according to claim 8, characterized in that when the locomotive runs to the first preset current frequency in an accelerated mode, k4 is closed, k2 and k3 are opened; when the locomotive reaches a second preset current frequency, closing k3, opening k2 and k 4; when the locomotive reaches a third preset current frequency, closing k2, opening k3 and k 4; wherein the first predetermined current frequency < the second predetermined current frequency < the third predetermined current frequency.

10. The application method according to claim 9, characterized in that when the locomotive runs to the first preset current frequency in a deceleration way, k3 is closed, k2 and k4 are opened; and when the locomotive runs to the second preset current frequency in a deceleration mode, closing the k4, and opening the k2 and the k 3.

Technical Field

The invention mainly relates to the technical field of transformers, in particular to a locomotive traction transformer and application thereof.

Background

In the novel locomotive traction system, when a train is started, because the starting current is large and the frequency variation range is large, a plurality of modules need to be connected in parallel for power supply, and circulation current exists among the modules; after the train is started to run to a certain speed, the output power of the transformer is continuously increased along with the continuous improvement of the speed of the train, the secondary side of the transformer adjusts the output voltage and the frequency according to the requirement, the transformer needs to normally work within the frequency range of 0-400 Hz, the transformer needs to have two functions of a reactor and a transformer, and the iron core, the primary winding and the like of the transformer need to be specially designed, so that the overall structure is complex.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the technical problems in the prior art, the invention provides the locomotive traction transformer which has the advantages of simple structure, simple and convenient operation, rich functions and circulation current inhibition, and correspondingly provides the application of the locomotive traction transformer in a locomotive traction system and locomotive control.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a locomotive traction transformer is formed by combining three single-phase transformers, primary coils of the three single-phase transformers are connected to different output phases of two inversion modules, and two ends of the primary coil of the same single-phase transformer are respectively connected with the same output phase of the two inversion modules; one end of the secondary coil of each single-phase transformer forms the output end of the three-phase transformer, and the other end of the secondary coil of each single-phase transformer is connected with each other and grounded; the neutral point of the primary coil of each single-phase transformer is connected with one end of the secondary coil through a first switch, and the secondary coil of each single-phase transformer is provided with a plurality of connecting switches for forming secondary coils with different turns when the secondary coils are switched on.

As a further improvement of the above technical solution:

the number of the connecting switches is 2-5.

The three-phase transformer is a dry type transformer or a liquid immersion type transformer.

The invention also discloses a locomotive traction system which comprises a rectification module, an intermediate direct current loop, a plurality of inversion modules and the locomotive traction transformer, wherein the rectification module, the intermediate direct current loop and the inversion modules are sequentially connected, and the input end of a three-phase transformer in the locomotive traction transformer is respectively connected with the output end of each inversion module.

The invention also discloses the application of the locomotive traction transformer in locomotive control, in the starting stage of the locomotive, a first switch in each single-phase transformer is closed, a neutral point of a primary coil is connected with one end of a secondary coil through the first switch, and meanwhile, each connecting switch is disconnected to open a secondary of the transformer, current directly supplies power to a load through the primary coil, and the three-phase transformer is in the working condition of an electric reactor;

when the locomotive normally runs, the first switch in each single-phase transformer is disconnected, the neutral point of the primary coil is disconnected with one end of the secondary coil, meanwhile, one of the connecting switches is closed, and the three-phase transformer is in the working condition of the transformer.

When the locomotive is in a normal running stage and needs to be accelerated, the number of turns of the secondary side coil is increased by switching the connecting switch, so that the output voltage of the three-phase transformer is increased, and the output power is increased; when speed reduction is needed, the number of turns of the secondary winding is reduced by switching the connecting switch, so that the output voltage of the three-phase transformer is reduced, and the output power is reduced accordingly.

Each connecting switch corresponds to the output current frequency of the transformer, and the corresponding connecting switch is switched when the corresponding preset current frequency is reached.

The number of the connecting switches is 3, and the connecting switches are k2, k3 and k4 respectively, wherein the number of turns of the corresponding secondary side coil is reduced in sequence when k2, k3 and k4 are switched on.

When the locomotive runs to the first preset current frequency in an accelerating mode, closing k4, opening k2 and k 3; when the locomotive reaches a second preset current frequency, closing k3, opening k2 and k 4; when the locomotive reaches a third preset current frequency, closing k2, opening k3 and k 4; wherein the first predetermined current frequency < the second predetermined current frequency < the third predetermined current frequency.

When the locomotive runs to a first preset current frequency in a deceleration mode, closing k3, opening k2 and k 4; and when the locomotive runs to the second preset current frequency in a deceleration mode, closing the k4, and opening the k2 and the k 3.

Compared with the prior art, the invention has the advantages that:

according to the locomotive traction transformer and the traction system, functions of the transformer and the reactor can be switched with each other through the mutual matching switching between the first switch and the connecting switches, for example, the first switch is closed to connect a neutral point of the primary coil and the secondary coil, and each connecting switch is disconnected to open the secondary coil, the neutral point of the primary coil is connected with the secondary coil, current directly supplies power to a load through the primary coil, and the three-phase transformer is in the working condition of the reactor; if the first switch is disconnected, the neutral point of the primary coil is disconnected with one end of the secondary coil, one of the connecting switches is closed, and the three-phase transformer is in a transformer working condition; the primary coil can be normally used as a primary winding of the transformer, and can also be used as a reactor coil after being switched by each switch, so that the transformer and reactor dual-demand situation can be suitable; and the switching between the transformer and the reactor can be realized through the switching of each switch, the structure is simple, the special design is not needed to be carried out in the transformer, the operation is simple and convenient, and the cost is low.

When the locomotive traction transformer is applied to locomotive control, when a train is just started, the traction transformer is in a working condition of the reactor through switching of the switch; two column coils of the single-phase transformer pass PWM wave currents with the same amplitude, frequency, pulse width and phase at the same time, but the directions of the two paths of currents are opposite, the generated magnetic fluxes are opposite, the magnetic fluxes are mutually offset, a small amount of leakage inductance is arranged in the coils, and the leakage inductance is utilized to restrain the circulating current between the two groups of inversion modules; the number of turns of the secondary coil of the traction transformer corresponds to different output voltages and frequency ranges, the number of turns of the secondary coil is changed in sequence through switching of the connecting switch, the transformer works under the working conditions of frequency modulation and capacitance adjustment, and in addition, the impulse voltage and current of each connecting switch during switching on and switching off are restrained by using the impedance of each coil through setting the sequence of the switching switch.

Drawings

Fig. 1 is a schematic circuit diagram of a transformer of the present invention in an embodiment.

Detailed Description

The invention is further described below with reference to the figures and the specific embodiments of the description.

As shown in fig. 1, in the locomotive traction transformer of the present embodiment, three single-phase transformers are combined to form a three-phase transformer, primary coils of the three single-phase transformers are connected to different output phases of two inversion modules, and two ends of the primary coil of the same single-phase transformer are respectively connected to the same output phase of the two inversion modules; one end of the secondary coil of each single-phase transformer forms the output end of the three-phase transformer, and the other ends of the secondary coils of each single-phase transformer are mutually connected and grounded; the neutral point of the primary coil of each single-phase transformer is connected with one end of the secondary coil through a first switch, and the secondary coil of each single-phase transformer is provided with a plurality of connecting switches for forming secondary coils with different turns when the secondary coils are switched on. The locomotive traction transformer can realize the mutual switching of the functions of the transformer and the reactor through the mutual matching switching between the first switch and the connecting switches, for example, the first switch is closed to connect the neutral point of the primary coil and the secondary coil, and each connecting switch is disconnected to open the secondary coil, the neutral point of the primary coil is connected with the secondary coil, the current directly supplies power to a load through the primary coil, and the three-phase transformer is in the working condition of the reactor; if the first switch is disconnected, the neutral point of the primary coil is disconnected with one end of the secondary coil, one of the connecting switches is closed, and the three-phase transformer is in a transformer working condition; the primary coil can be normally used as a primary winding of the transformer, and can also be used as a reactor coil after being switched by each switch, so that the transformer and reactor dual-demand situation can be suitable; and the switching between the transformer and the reactor can be realized through the switching of each switch, the structure is simple, the special design is not needed to be carried out in the transformer, the operation is simple and convenient, and the cost is low.

In the embodiment, the locomotive traction transformer adopts a combined structure of a three-phase transformer combined by three single-phase transformers, the single-phase connection method is Ii0, and the three-phase combined transformation method is Dyn11 or Dyn 5; the three-phase transformer is a dry type transformer or a liquid immersion type transformer and the like. In addition, the number of the connecting switches is 2-5, in a preferred embodiment, the number of the connecting switches is 3, and the number of the connecting switches is k2, k3 and k4, wherein the number of turns of the corresponding secondary side coils is reduced in sequence when k2, k3 and k4 are switched on.

The invention also discloses a locomotive traction system which comprises a rectification module, an intermediate direct current loop, a plurality of inversion modules and the locomotive traction transformer, wherein the rectification module, the intermediate direct current loop and the inversion modules are sequentially connected, and the input end of a three-phase transformer in the locomotive traction transformer is respectively connected with the output end of each inversion module. Specifically, the number of the inversion modules is two, namely D1 and D2; the three single-phase transformers are respectively T1, T2 and T3, wherein two ends A2 of a primary coil of the T1 are respectively connected with a U1 phase of the inverter module D1 and a U2 of the inverter module D2; two ends B2 of a primary coil of the T2 are respectively connected with a V1 phase of an inverter module D1 and a V2 phase of an inverter module D2; two ends C2 of the primary coil of T3 are respectively connected with the W1 phase of the inverter module D1 and the W2 phase of the inverter module D2.

The locomotive traction system comprises the transformer, has the advantages of the transformer, can be suitable for different working conditions, realizes variable frequency capacity adjustment of the transformer in a wide range of 0-400 Hz, and meets the traction power output of a high-speed train in different running states. Specifically, in the starting stage of the locomotive, a first switch in each single-phase transformer is closed, a neutral point of a primary coil is connected with one end of a secondary coil through the first switch, meanwhile, each connecting switch is disconnected, so that the secondary coil of the transformer is opened, current directly supplies power to a load through the primary coil, and the three-phase transformer is in the working condition of the reactor;

when the locomotive normally runs, a first switch in each single-phase transformer is disconnected, a neutral point of a primary coil is disconnected with one end of a secondary coil, meanwhile, one connecting switch is closed, and the three-phase transformer is in a transformer working condition; when the locomotive needs to be accelerated in a normal running stage, the number of turns of the secondary side coil is increased by switching the connecting switch, so that the output voltage of the three-phase transformer is increased, and the output power is increased; when speed reduction is needed, the number of turns of the secondary winding is reduced by switching the connecting switch, so that the output voltage of the three-phase transformer is reduced, and the output power is reduced accordingly.

In the embodiment, each connecting switch corresponds to the preset current frequency of the organic vehicle, and the corresponding connecting switch is switched when the corresponding preset current frequency is reached; the number of the connection switches is 3 for explanation, the connection switches comprise k2, k3 and k4, wherein the turns of the corresponding secondary side coils are reduced in sequence when k2, k3 and k4 are switched on, and the first switch is k 1. When the locomotive runs to the first preset current frequency in an accelerating mode, closing k4, opening k2 and k 3; when the locomotive reaches a second preset current frequency, closing k3, opening k2 and k 4; when the locomotive reaches a third preset current frequency, closing k2, opening k3 and k 4; wherein the first predetermined current frequency < the second predetermined current frequency < the third predetermined current frequency.

When the locomotive runs to a first preset current frequency in a deceleration mode, closing k3, opening k2 and k 4; and when the locomotive runs to the second preset current frequency in a deceleration mode, closing the k4, opening the k2 and opening the k3, and repeating the steps.

The above scheme is generally described below with reference to a full embodiment:

when a train is just started, the k1 switch is closed, the k2, the k3 and the k4 switches are all disconnected, the secondary side of the transformer is open, current directly supplies power to a load through the primary side winding, and the traction transformer is in a reactor working condition at the moment; the single-phase two-column coil simultaneously passes PWM wave current with the same amplitude, frequency, pulse width and phase, but the directions of the two paths of current are opposite, the generated magnetic fluxes are also opposite, the magnetic fluxes are mutually offset, a small amount of leakage inductance is arranged in the coil, and the leakage inductance is utilized to restrain the circulating current between the two groups of inversion modules;

when the train runs to a certain speed, the current output by the two groups of modules is gradually changed from direct current to PWM waves with a certain frequency (the locomotive reaches a preset speed), the k1 switch is switched off, the k4 switch is switched on, and the transformer enters the working condition of the transformer; along with the continuous increase of the power of the transformer, the frequency of the transformer is also continuously improved, when the current frequency reaches the 2 nd threshold value, the k3 switch is closed, the k4 switch is opened, the working output voltage of the transformer is improved, and the output power is also increased; when the current frequency reaches the 3 rd threshold value, the k2 switch is closed, the k3 switch is opened, and the working output voltage and the output power of the transformer reach the maximum;

when the train operates at a reduced speed, when the frequency of the PWM waves output by the two groups of modules is gradually reduced to be lower than a 3 rd threshold value, the k3 switch is closed, and the k2 switch is opened; when the voltage reaches the 2 nd threshold value, the k4 switch is closed, the k3 switch is opened, and the working output voltage and the output power of the transformer are reduced; the traction transformer repeats the steps in each working cycle;

the number of turns of the secondary coil of the traction transformer corresponds to different output voltages and frequency ranges, the number of turns of the secondary coil is changed in sequence through switching of the connecting switch, the transformer works under the working conditions of frequency modulation and capacitance adjustment, and in addition, the impulse voltage and current of each connecting switch during switching on and switching off are restrained by using the impedance of each coil through setting the sequence of the switching switch.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present invention, or modify equivalent embodiments to equivalent variations, without departing from the scope of the invention, using the teachings disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention should fall within the protection scope of the technical scheme of the present invention, unless the technical spirit of the present invention departs from the content of the technical scheme of the present invention.