阅读说明：本技术 一种变流器 (Current transformer ) 是由 王雄 翁星方 唐龙 谢湘剑 宋乾儒 林文彪 张祥 邹今换 叶文玉 董其爱 吴雪峰 于 2018-06-07 设计创作，主要内容包括：本申请公开了一种变流器,包括：N个PWM整流器和单相滤波电抗器组,每个PWM整流器对应一个单相滤波电抗器组；每个PWM整流器的交流输出端与单相滤波电抗器组的一侧串联,每个单相滤波电抗器组的另一侧相互连接且作为交流侧接入点,每个PWM整流器的直流侧相互并联且作为直流侧连接入点；每个PWM整流器采用预设的载波移相算法,实现每个PWM整流器错相工作,N为大于等于2的正整数；本申请在交流电源或负载AC和直流电源或负载DC之间串联多组相互并联一一对应的单相滤波电抗器组Linv和PWM整流器INV,结合预设的载波移相算法,能够保证每个PWM整流器INV错相工作,从而减少谐波,提高变流器的功率因数。(The application discloses converter includes: n PWM rectifiers and single-phase filter reactor groups, wherein each PWM rectifier corresponds to one single-phase filter reactor group; the alternating current output end of each PWM rectifier is connected with one side of each single-phase filter reactor group in series, the other side of each single-phase filter reactor group is connected with each other and serves as an alternating current side access point, and the direct current side of each PWM rectifier is connected with each other in parallel and serves as a direct current side access point; each PWM rectifier adopts a preset carrier phase-shifting algorithm to realize the phase-staggered work of each PWM rectifier, and N is a positive integer greater than or equal to 2; according to the method, multiple groups of single-phase filter reactor sets Linv and PWM rectifiers INV which are mutually connected in parallel and in one-to-one correspondence are connected in series between an alternating current power supply or a load AC and a direct current power supply or a load DC, and each PWM rectifier INV can be guaranteed to work in a phase-staggered mode by combining a preset carrier phase-shifting algorithm, so that harmonic waves are reduced, and the power factor of a converter is improved.)

1. A current transformer, comprising: n PWM rectifiers and single-phase filter reactor groups, wherein each PWM rectifier corresponds to one single-phase filter reactor group; the alternating current output end of each PWM rectifier is connected with one side of each single-phase filter reactor group in series, the other side of each single-phase filter reactor group is connected with each other and serves as an alternating current side access point, and the direct current side of each PWM rectifier is connected with each other in parallel and serves as a direct current side access point; and controlling each PWM rectifier by using a preset carrier phase-shifting algorithm to realize the phase-staggered work of each PWM rectifier, wherein N is a positive integer greater than or equal to 2.

2. The converter according to claim 1, wherein each PWM rectifier comprises three sets of fully-controlled switching devices, each set of fully-controlled switching devices comprises a first fully-controlled switching device and a second fully-controlled switching device, an output terminal of the first fully-controlled switching device is connected to an input terminal of the second fully-controlled switching device, an input terminal of the first fully-controlled switching device of each set of fully-controlled switching devices is connected to each other as a dc output terminal on a dc side, an output terminal of the second fully-controlled switching device of each set of fully-controlled switching devices is connected to each other as a dc input terminal on a dc side, a control terminal of each fully-controlled switching device is connected to a corresponding control circuit, receives the preset carrier phase shift algorithm, and a common terminal of the first fully-controlled switching device and the second fully-controlled switching device is connected to the single-phase filter reactor set as an ac output terminal.

3. The converter according to claim 2, wherein said fully controlled switching device is an IGBT.

4. The converter according to claim 1, further comprising: and the direct current side of the rectifier bridge is connected with each PWM rectifier in parallel, and the alternating current side of the rectifier bridge is connected with an access point of the alternating current side of the N single-phase filter reactor groups.

5. The converter according to claim 4, further comprising a bank of single-phase filter inductors connected to said AC side access points.

6. the converter according to claim 4, wherein the rectifier bridge comprises three sets of unidirectional conducting devices, each set of unidirectional conducting devices comprises a first unidirectional conducting device and a second unidirectional conducting device, a cathode of the first unidirectional conducting device is connected with an anode of the second unidirectional conducting device, an anode of the first unidirectional conducting device of each set of unidirectional conducting devices is connected with each other as an output end of a DC side of the rectifier bridge, a cathode of the second unidirectional conducting device of each set of unidirectional conducting devices is connected with each other as an input end of the DC side of the rectifier bridge, and a common end of the first unidirectional conducting device and the second unidirectional conducting device of each set of unidirectional conducting devices is connected with an AC side access point of the first single-phase filter reactor set and the second single-phase filter reactor set as an AC side of the rectifier bridge.

7. The converter according to claim 6, wherein the unidirectional conducting device is a diode or a thyristor.

8. The converter according to any of claims 1 to 7, wherein the carrier phase shifting algorithm is carrier-error phase shiftingSPWM of (1), wherein N denotes the number of rectifiers, and N is N.

9. The converter according to any of claims 1 to 7, wherein the carrier phase shifting algorithm is carrier time-staggeredWhere N denotes the number of rectifiers, and N is equal to N.

Technical Field

The invention relates to the technical field of rail transit power supply, in particular to a current transformer.

Background

With the progress of science and technology, equipment which can only meet the production requirements does not meet the requirements of modern society, energy conservation and emission reduction are realized on the basis of meeting the production requirements, and in order to respond to the call of national energy conservation and emission reduction and avoid the brake energy from being consumed through a resistor, in this year, an energy feeding device is more and more widely applied to a subway line, namely, an energy feeding branch circuit is connected in parallel to a subway traction rectifier unit loop and used for feeding the train brake energy back to an alternating current power grid, so that the energy can be secondarily utilized.

Disclosure of Invention

In view of the above, the present invention provides a converter, which can rectify traction and also can perform inverse feedback, reduce harmonic waves, and improve power factor. The specific scheme is as follows:

A current transformer, comprising: n PWM rectifiers and single-phase filter reactor groups, wherein each PWM rectifier corresponds to one single-phase filter reactor group; the alternating current output end of each PWM rectifier is connected with one side of each single-phase filter reactor group in series, the other side of each single-phase filter reactor group is connected with each other and serves as an alternating current side access point, and the direct current side of each PWM rectifier is connected with each other in parallel and serves as a direct current side access point; and controlling each PWM rectifier by using a preset carrier phase-shifting algorithm to realize the phase-staggered work of each PWM rectifier, wherein N is a positive integer greater than or equal to 2.

Optionally, each PWM rectifier includes three sets of fully-controlled switching devices, each set of fully-controlled switching device includes a first fully-controlled switching device and a second fully-controlled switching device, an output end of the first fully-controlled switching device is connected to an input end of the second fully-controlled switching device, input ends of the first fully-controlled switching devices of each set of fully-controlled switching devices are connected to each other to serve as a dc output end on a dc side, output ends of the second fully-controlled switching devices of each set of fully-controlled switching devices are connected to each other to serve as a dc input end on the dc side, a control end of each fully-controlled switching device is connected to a corresponding control circuit to receive the preset carrier phase shift algorithm, and a common end of the first fully-controlled switching device and the second fully-controlled switching device is connected to a single-phase filter reactance as an ac output end.

optionally, the fully-controlled switching device is an IGBT.

Optionally, the method further includes: and the direct current side of the rectifier bridge is connected with each PWM rectifier in parallel, and the alternating current side of the rectifier bridge is connected with an access point of the alternating current side of the N single-phase filter reactor groups.

Optionally, the single-phase filter further includes a single-phase filter inductor group connected to the ac side access point.

Optionally, the rectifier bridge includes three sets of unidirectional conduction devices, each set of unidirectional conduction device includes a first unidirectional conduction device and a second unidirectional conduction device, a negative electrode of the first unidirectional conduction device is connected with a positive electrode of the second unidirectional conduction device, a positive electrode of the first unidirectional conduction device of each set of unidirectional conduction device is connected with a positive electrode of the second unidirectional conduction device as an output end of a direct current side of the rectifier bridge, a negative electrode of the second unidirectional conduction device of each set of unidirectional conduction device is connected with an input end of the direct current side of the rectifier bridge, and a common end of the first unidirectional conduction device and the second unidirectional conduction device of each set of unidirectional conduction device is connected with an alternating current side of the rectifier bridge and an alternating current side access point of the first single-phase filter reactor set and the second single-phase filter reactor set.

Optionally, the unidirectional conducting device is a diode or a thyristor.

Optionally, the carrier phase shift algorithm is carrier phase shiftSPWM of (1), wherein N denotes the number of rectifiers, and N is N.

Optionally, the carrier phase shift algorithm is carrier time shiftWhere N denotes the number of rectifiers, and N is equal to N.

In the present invention, a current transformer includes: n PWM rectifiers and single-phase filter reactor groups, wherein each PWM rectifier corresponds to one single-phase filter reactor group; the alternating current output end of each PWM rectifier is connected with one side of each single-phase filter reactor group in series, the other side of each single-phase filter reactor group is connected with each other and serves as an alternating current side access point, and the direct current side of each PWM rectifier is connected with each other in parallel and serves as a direct current side access point; each PWM rectifier adopts a preset carrier phase-shifting algorithm to realize the phase-staggered work of each PWM rectifier, and N is a positive integer greater than or equal to 2; according to the invention, multiple groups of single-phase filter reactor sets Linv and PWM rectifiers INV which are mutually connected in parallel and in one-to-one correspondence are connected in series between an alternating current power supply or load AC and a direct current power supply or load DC, and a preset carrier phase shift algorithm is combined, so that each PWM rectifier INV can be ensured to work in a phase-staggered manner, thus harmonic waves are reduced, and the power factor of the converter is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a current transformer disclosed in an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of another current transformer disclosed in the embodiment of the present invention;

Fig. 3 is a main circuit diagram of a bidirectional converter system according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention discloses a current transformer, which is shown in figure 1 and comprises: the system comprises N PWM rectifiers INV and single-phase filter reactor groups Linv, wherein each PWM rectifier INV corresponds to one single-phase filter reactor group Linv; the alternating current end of each PWM rectifier INV is connected with one side of a single-phase filter reactor group Linv in series, the other side of each single-phase filter reactor group Linv is connected with each other and serves as an alternating current side access point, and the direct current side of each PWM rectifier INV is connected with each other in parallel and serves as a direct current side access point; and controlling each PWM rectifier by using a preset carrier phase shift algorithm to realize the phase-staggered work of each PWM rectifier INV, wherein N is a positive integer greater than or equal to 2.

Wherein each PWM rectifier INV comprises three groups of fully-controlled switch devices 11, each group of fully-controlled switch devices 11 comprises a first fully-controlled switch device S1 and a second fully-controlled switch device S2, an output end of the first fully-controlled switch device S1 is connected with an input end of the second fully-controlled switch device S2, an input end of the first fully-controlled switch device S1 of each group of fully-controlled switch devices 11 is connected with each other to serve as a direct current input end of a direct current side, an output end of the second fully-controlled switch device S2 of each group of fully-controlled switch devices 11 is connected with each other to serve as a direct current output end of the direct current side, a control end of each fully-controlled switch device S1 or S2 is connected with a corresponding control circuit to receive a preset carrier wave reactance algorithm, a common end of the first fully-controlled switch device S1 and the second fully-controlled switch device S2 serves as an alternating current end to be connected with a single-phase filter reactance group Linv, each single-phase-shift reactor group comprises 3 single-phase filter reactance reactors, respectively connected to three phases at the AC side of the PWM rectifier INV.

Specifically, a common end, namely an alternating current side access point, of each single-phase filter reactor group Linv is connected with a three-phase alternating current power supply or an alternating current load AC, each PWM rectifier INV is connected in series with a direct current power supply or a direct current load DC, and a direct current side access point of the PWM rectifier INV comprises a direct current input end and a direct current output end which are respectively connected with a positive electrode and a negative electrode of the direct current power supply or the direct current load; the fully-controlled switching device can be an IGBT, and when the fully-controlled switching device is an IGBT, an emitter of the IGBT serves as an output end of the fully-controlled switching device, a collector of the IGBT serves as an input end of the fully-controlled switching device, and a gate of the IGBT serves as a control end of the fully-controlled switching device.

It should be noted that, in order to ensure that each PWM rectifier INV can perform phase-staggered operation and reduce harmonic, the carrier phase-shifting algorithm adopts carrier phase-staggered operationSPWM, or carrier miscarriageWherein N denotes the number of rectifiers, N is N, T_sRepresents a sampling period; for example, one converter includes two PWM rectifiers INV, an SPWM with carrier offset 180 ° is adopted, one converter includes three PWM rectifiers INV, an SPWM with carrier offset 120 ° is adopted, and similarly, carrier offset is performed according to P included in one converterWM rectifier INV number conversionAnd obtaining the corresponding carrier time error by the value of the middle n.

It can be understood that the conduction control is performed on the fully-controlled devices of the PWM rectifiers INV by adopting a preset carrier phase shift algorithm, and the single-phase filter reactor sets Linv corresponding to the PWM rectifiers INV one to one are combined, so that the multiple PWM rectifiers INV can perform phase-staggered operation, multiple chopping phase-staggered harmonic elimination is realized, and the harmonic is reduced.

For example, a bidirectional converter system includes four PWM rectifiers INV, each of which uses the same modulation wave but uses a predetermined carrier phase errorThe SPWM carrier phase shift algorithm shows that triangular carriers of the four PWM rectifiers INV are sequentially staggered by 90 degrees, a first PWM rectifier INV is 0 degree, a second PWM rectifier INV is 90 degrees, a third PWM rectifier INV is 180 degrees and a fourth PWM rectifier INV is 270 degrees, so that current harmonics are mutually offset, and the purpose of reducing the harmonics is achieved

Therefore, in the embodiment of the invention, a plurality of groups of single-phase filter reactor sets Linv and PWM rectifiers INV which are mutually connected in parallel and in one-to-one correspondence are connected in series between the alternating current power supply or load AC and the direct current power supply or load DC, and the phase-staggered work of each PWM rectifier INV can be ensured by combining a preset carrier phase-shifting algorithm, so that harmonic waves are reduced, and the power factor of the converter is improved.

The embodiment of the invention discloses a specific converter, and compared with the previous embodiment, the technical scheme is further explained and optimized by the embodiment. Referring to fig. 2, specifically:

When the converter is applied to the technical field of rail transit power supply, such as a subway power supply circuit, a direct current power supply or a load DC can be broken, in order to ensure that the converter can bear large short-circuit current and avoid damage of a fully-controlled switch device in the converter, the converter can also comprise a rectifier bridge Diode, a short-circuit loop between the converter and the direct current power supply or the load DC is constructed by utilizing the rectifier bridge Diode, and the rectifier bridge Diode is short-circuited with a PWM rectifier INV after the direct current power supply or the load DC is short-circuited, so that the fully-controlled switch device in the converter is protected; the direct current side of the rectifier bridge Diode is connected with each PWM rectifier INV in parallel, and the alternating current side of the rectifier bridge Diode is connected with the alternating current side access points of the N single-phase filter reactor groups Linv.

Specifically, the rectifier bridge Diode includes three groups of unidirectional conducting devices 21, each group of unidirectional conducting devices 21 includes a first unidirectional conducting device D1 and a second unidirectional conducting device D2, a cathode of the first unidirectional conducting device D1 is connected to an anode of the second unidirectional conducting device D2, an anode of the first unidirectional conducting device D1 of each group of unidirectional conducting devices 21 is connected to each other to serve as an output end of a direct current side of the rectifier bridge Diode, a cathode of the second unidirectional conducting device D2 of each group of unidirectional conducting devices 21 is connected to serve as an input end of the direct current side of the rectifier bridge, and a common end of the first unidirectional conducting device D1 and the second unidirectional conducting device D2 of each group of unidirectional conducting devices 21 serves as an alternating current side of the rectifier bridge Diode and is connected to an access point of an alternating current side of the first single-phase filter reactance group Linv and an alternating current side of the second single-phase filter reactance group Linv.

The unidirectional device D1 or D2 may be a diode or a thyristor.

It can be understood that, when the dc power supply or the load AC is short-circuited, since the conduction voltage drop of the unidirectional conducting device in the rectifier bridge Diode is lower than the conduction voltage drop of the fully-controlled switching device in the PWM rectifier INV, the short-circuited current of the dc power supply or the load AC returns to the dc power supply or the load AC again through the rectifier bridge Diode, so as to avoid the short-circuited current passing through the PWM rectifier INV and the damage of the fully-controlled switching device in the PWM rectifier INV.

furthermore, in order to limit the magnitude of the short-circuit current, the converter may further include a single-phase filter inductor group Lg connected to the ac side access point, where the single-phase filter inductor group Lg includes 3 single-phase filter inductors respectively connected to three phases on the ac side.

Referring to fig. 3, a main circuit diagram of a bidirectional converter system disclosed in the embodiment of the present invention includes a first converter 3, a second converter 4, a double split transformer T, a dc traction network 1, an ac bus 2, a first diode rectifier bridge DIO1, a first PWM rectifier INV1, a second PWM rectifier INV2, a third PWM rectifier INV3, a fourth PWM rectifier INV4, a first single-phase filter reactor bank L1, a second single-phase filter reactor bank L2, a third single-phase filter reactor bank L3, a fourth single-phase filter reactor bank L4, and a second diode rectifier bridge DIO 2.

Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The above detailed description of the converter provided by the present invention has been presented, and the principle and the implementation of the present invention are explained in the present document by applying specific examples, and the above description of the embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.