Title of Invention

TRACTION SYSTEM IN VOLTAGE MODE INCLUDING POWER SUPPLY BUSES OF AN ELECTRIC TRACTION VEHICLE

Abstract ABSTRACT TRACTION SYSTEM IN VOLTAGE MODE INCLUDING POWER SUPPLY BUSES OF AN ELECTRIC TRACTION VEHICLE The present invention relates to a traction system in voltage mode including power supply buses of an elec¬tric traction vehicle, the said power supply buses each including a 2F filter, characterized in that the mid¬points of the said 2F filters of the set of said power supply buses are linked together.
Full Text The present invention relates to electric traction systems, in general, and relates, more par¬ticularly, to a traction system in voltage mode includ¬ing power supply buses of an electric traction vehicle.
In the field of electric traction systems, GTO {GATE TURN OFF} technology favours the use of electri¬cal power layouts of an electric traction system in¬cluding buses of the common-buses type.
IGBT (INSULATED GATE BIPOLAR TRANSISTOR) tech¬nology is likely to favour the implementation of elec¬trical power layouts of an electric traction system in¬cluding buses of the separate-buses type.
Electrical power layouts of an electric trac¬tion system of the prior art including buses of the common-buses type have the advantages that:
- all the traction power is shared among the forced-commutation single-phase bridges (PMCF from now on) on the same bus; there is therefore no overcurrent within the PMCFs in the event of dispersion in the traction powers from each inverter,
- in the case of a bus consisting of a number N of PMCFs, the interlacing of the N PMCFs makes it pos¬sible to minimize all the spectral lines from the fam¬ily 1 to the family N-1, giving rise to a level of per¬formance, from the point of view of the absence of os¬cillations on the catenary network, which is all the higher since the level of the value of the primary cur¬rent IPE is assured,
- in the case of an isolated PMCF, the total starting force is still provided while complying with the quality of the interlacing of the remaining PMCFs.
- the auxiliary unit is easily installed on the DC bus.

yucn electrical power layouts of an electric traction system of the prior art including buses of the common-buses type have the drawbacks that:
- a short-circuit of the common bus entails an excess torque on all the traction motors,
- because the comrnutation of the IGBTs needs a low circuit inductance, a short-circuit on all the ca¬pacitors of the common bus may give rise to an overcur-rent phenomenon.
The electrical power layouts of an electric traction system of the prior art including buses of the type with separate buses per axle have the advantages that:
- in the event of a short-circuit on a bus, the
overcurrent is minimized, and the excess torque of the
motor is limited to a single inverter; there is there¬
fore no influence on the other buses.
Such electrical power layouts of an electric traction system of the prior art including buses of the type with separate buses per axle have the drawbacks that:
- with the operation of each bus being inde¬pendent, because of the dispersions in the measurements of the DC voltages and of the traction powers on each inverter, the quality of the interlacing of the N PMCFs on N separate buses cannot be assured; the harmonics and the value of the primary current IPE are therefore degraded.
- because of this same problem of the interlac¬ing, the PMCFs have to be slightly over-dimensioned,
- the auxiliary units are difficult to install on the separate buses.
Table 1 below brings together all the perform¬ance aspects of the various electrical power layouts of an electric traction system of the prior art.


TABLE 1 ftncther object of the invention is an electric traction system including power supply buses of an electric traction vehicle exhibiting the advantages of traction systems including power supply buses of the common-buses type according to the prior art, as well as the advantages of traction systems including power supply buses of the separate-buses type according to the prior art.
Another object of the invention is an electric traction system including power supply buses of an electric traction vehicle not exhibiting the drawbacks of the electric traction systems according to the prior art.
Other object of the invention is an electric traction system including power supply buses of an electric traction vehicle in which the overall perform¬ance is improved.

In accordance with the invention, the traction system in voltage mode including power supply buses of an electric traction vehicle is as characterized below:
One advantage of the traction system in voltage mode including power supply buses of an electric traction vehicle of the invention is better performance of the powers as well as of the harmonics.
Accordingly, the present invention provides a traction system in voltage mode comprising power supply buses of an electric traction vehicle, in which each bus of at least a part of the said power supply buses has a 2F filter, characterized in that the mid-points of the said 2F filters of the said power supply buses are linked together.
Other purposes, characteristics and advantages of the invention will emerge upon reading the description of the preferred embodiment of a traction system in voltage mode including power supply buses of an electric traction vehicle, the description being given in connection with the drawings in which :
-Figure I is an electrical layout of a electric traction system including buses of the separate-buses type in accordance with the prior art,
- Figures lA to ID show, respectively, the levels of harmonics and the shape of the four secondar> currents obtained by the electrical layout of Figure 1.
- Figure 2 is a electrical layout of an electric traction system including buses of the type with common buses per bogey in accordance with the prior art,
- Figures 2A to 2D show, respectively, the levels of harmonics and the shape of the tour secondaiy currents obtained by the electrical layout of Figure 2.
- Figure 3 is an electrical layout of an electric traction system including buses of the common buses type in accordance with the prior art,

Figures 3A and 3B show, respectively, the levels of harmonics and the shape of the four sccondary currents obtained by the electrical layout of Figures,
Figure 4 Is an electrical layout of a first preferred embodiment of an electric traction svslcm in

eluding buses of the si=iuj--(-ommon Duses type in accor¬dance with the invention.
- Figures -^A and 4B show, respectively, the
levels of harmonics and the shape of the four secondary
currents obtained by the electrical layout of Figure 4,
- Figure 5 is an electrical layout of another
preferred embodiment of the electric traction system
including two buses of the semi-common buses type in
accordance with the invention.
Figures 5A to 5C show, respectively, the equivalent layouts of the electrical layout of Figure 5, in the case of direct currents, of 2F currents and of a short-circuit of the higher bus,
- Figure 6 is an electrical layout of another preferred embodiment of an electric traction system in¬cluding of the semi-common buses type in accordance with the invention.
- Figure 7 is an electrical layout of another preferred embodiment of an electric traction system in¬cluding buses of the semi-common buses type in accor¬dance with the invention.
Figure 1 is an electrical layout of an electric traction system including buses of the separate-buses type in accordance with the prior art.
This Figure 1 shows a traction system with four buses, each bus including a PMCF and a 2F filter.
Figures lA to ID show, respectively, the levels of harmonics and the shape of the four secondary cur¬rents obtained by the electrical layout of Figure 1 in normal operation with a PMCF at rest.
Figure 2 is an electrical layout of an electric traction system including buses of the type with common buses per bogey in accordance with the prior art.
This Figure 2 shows a traction system with four buses, each bus including a PMCF and a 2F filter, the

buses being configured in pairs so that each pair of buses is associated with two PMCFs.
Figures 2A to 2D show, respectively, the levels of harmonics and the shape of the four secondary cur¬rents obtained by the electrical layout of Figure 2, in normal operation with a motor stopped.
Figure 3 is an electrical layout of an electric traction system including buses of the common-buses type in accordance with the prior art.
This Figure 3 shows a traction system with four buses, each bus including a PMCF, only one of the buses including a 2F filter, the buses being configured in such a way that the set of buses are associated with the four PMCFs.
Figures 3A and 3B show, respectively, the lev¬els of harmonics and the shape of the four secondary currents obtained by the electrical layout of Figure 3.
Figure 4 is an electrical layout of a first preferred embodiment of an electric traction system in¬cluding buses of the semi-common buses type in accor¬dance with the invention.
The traction system in voltage mode includes power supply buses of an electric traction vehicle.
The power supply buses each include a 2F filter the mid-points of which are linked together, preferably by means of switching elements.
Thus Figure 4 shows a four-bus traction system, each bus including a PMCF and a 2F filter, the 2F fil¬ters being configured in such a way that the mid-points of the 2F filters of the set of power supply buses are linked together.
Figures 4A and 4B show, respectively, the lev¬els of harmonics and the shape of the four secondary currents obtained by the el f*'^*"■*"!'"=*'■ T ='"^"i- •-■^ i?-!:-n,^„ A

Figure 5 represents the electrical layout of the first preferred embodiment of the electric traction system including two buses of the semi-common buses type in accordance with the invention.
Figures 5A to 5C show the equivalent diagrams of the electrical layout of Figure 5, in the case, re¬spectively, of direct currents, of 2F currents and of a short-circuit of the higher bus,
Figure 6 is an electrical layout of another preferred embodiment of an electric traction system in¬cluding buses of the semi-common buses type in accor¬dance with the invention.
In accordance with this other preferred embodi¬ment of the electric traction system in accordance with the invention, the power supply buses are linked di¬rectly by means of self-inductive elements.
Figure 7 is an electrical layout of another preferred embodiment of an electric traction system in¬cluding buses of the semi-common buses type in accor¬dance with the invention.
In accordance with this other preferred embodi¬ment of the electric traction system in accordance with the invention, the first half of the power supply buses each includes a 2F filter, the other half of the power supply buses is linked in pairs to the first half of the power supply buses and the mid-points of the 2F filters of the first half of the power supply buses are linked together.
SIMULATIONS
The simulations defined below are carried out on four types of electrical power layout of an electric traction system of the prior art, including buses with the following bus type
■ Configuration of the traction systems: Option 1 according to the prior art:

Four-bus traction system, ^ach bus including a PMCF and
a 2F filter (Figure 1).
Option 2 according to the prior art:
Four-bus traction system, each bus including a PMCF and
a 2F filter, the buses being configured in pairs in
such a way that each pair of buses is associated with
two PMCFs (Figure 2).
Option 3 according to the prior art:
Four-bus traction system, each bus including a PMCF,
only one of the buses including a 2F filter, the buses
being configured in such a way that the set of buses
are associated with 4 PMCFs (Figure 3).
Option 4 in accordance with the invention:
Four-bus traction system, each bus including a PMCF and
a 2F filter, the 2F filters being configured in such a
way that the mid-points of the filters 2F of the set of
power supply buses are linked together (Figure 4).
Results of the simulation in the case where slight dispersions exist between the buses.
Table 2 below indicates the results of the simulation for limited dispersions between the DC buses.

OPTION 1 OPTION 2 OPTION
3 OPTION 4
Number of buses 4 2 1 -
Number of PMCFs and of inverters per bus 1 2 4
Number of interlaced PMCFs 4 4 4
Value of the Uc disper¬sion on bus 1 10% 10% 0%
Value of the power dis¬persion on bus 1 10% 10% 0%


TABLE 2 The comparison of the levels of harmonics for small dispersions due to an error in measurement of Uc or in the control of the inverters shows that an imbal¬ance of the order of 10% of Uc and of the power on a bus gives rise to:
- a first family of spectral lines and 58% in¬
crease in the value of the primary current IPE, in the
case of four separate buses each consisting of one
PMCF,
- a second family of spectral lines and 35% in¬
crease in the value o£ the primary current IPE, in the
case of two separate buses each consisting of two
PMCFs.
The results appear acceptable for the separate buses, provided that the catenary is perfect.
However, if the locomotive is far from the sub¬station under a catenary, the harmonics and the IPE of the current risk being substantially degraded.
Results of the simulation in the case where a significant imbalance exists between the buses.
Table 3 below indicates the results of the simulation for a significant difference in power be¬tween inverters.


TABLE 3
In the case in which the difference in power is significant between the separate buses, the harmonics and the IPE can no longer be assured.
As to option 1, if the inverter on bus 1 is cut off (hypothetical case) , the IPE can reach four times more than normal.
As to option 2, if the inverter on bus 1 is cut off, the IPE can reach twice the normal.
This type of situation may possibly occur when the power of the auxiliary unit linked to the DC trac¬tion buses is significant.
Option 4 in accordance with the invention, called separate-common bus layout, shows identical per¬formance to the layout with common buses.

figure 5 is an electrical layout of another preferred embodiment of the electric traction system including tv;o buses of the semi-common buses type in accordance with the invention.
Figures 5A to 5C show, respectively, the equivalent diagrams of the electrical layout of Figure 5, in the case of DC currents, of 2F currents and of a short circuit of the upper bus.
The electrical layout of the electric traction system including two buses of the semi-common buses type in accordance with the invention includes a link between the individual buses via inductors.
In accordance with the first preferred embodi¬ment of the electrical layout of an electric traction system including buses of the semi-common buses type in accordance with the invention, the electric traction system includes a link between the 2F filters (Figure 4) .
The advantage of this first preferred embodi-Tient of the electrical layout is of preserving the ad-i/-antages of the separate buses, as well as the advan¬tages of the common buses without adding significant amounts of equipment.
In the case of steady-state operation of the electric traction system in accordance with the inven-;ion, the linking of the 2F filters allows energy to 3ass between the buses, and imposes uniformity of the 5C voltages, Uc.
The currents of the PMCFs are therefore made miform, the advantage of the electric traction system jith common buses is thus preserved.
In the case of a short circuit of a DC bus, the iupply of energy from the other buses passes through ■.he 2F inductors.

The advantage of the electric traction system with separate buses is thus preserved.
CONCLUSIONS
In order to avoid overcurrents in the event of a short circuit of the DC bus, the choice of the layout w ith cont inuous-separate bus degrades the performance of the harmonics and of the IPE because of the disper¬sion of the voltages Uc and loads.
However, because of the appearance of low-order harmonics, the degradation risks becoming aggravated in the event of resonance of the catenary.
The applicant also has the merit of proposing a power layout, called a common-buses layout, based on the layout known as separate-buses layout, the particu¬lar feature of this layout being that of placing the 2F capacitors in common on all the buses.
The simulation results thus show that the power layout with semi-common buses in accordance with the invention exhibits the same harmonics and the same value of the IPE as those exhibited by the common-buses layout of the prior art, while preserving the advan¬tages of the separate-buses power layout of the prior art as far as the transient states are concerned.


WE CLAIM:
1. A traction system in voltage mode comprising power supply buses of an
electric traction vehicle, in which each bus of at least a part of the said power
supply buses has a 2F filter, characterized in that the mid-points of the said 2F
filters of the said power supply buses are linked together.
2. The traction system in voltage mode as claimed in claim 1, wherein ihc said part constitutes a first half of the said power supply buses, the other half of the said power supply buses being linked in pairs to the said first half of the said supply buses.
3. A traction system in voltage mode, substantially as herein described with reference to the accompanying drawings

Documents:

0093-mas-1999 abstract-duplicate.pdf

0093-mas-1999 abstract.pdf

0093-mas-1999 claims-duplicate.pdf

0093-mas-1999 claims.pdf

0093-mas-1999 correspondence-others.pdf

0093-mas-1999 correspondence-po.pdf

0093-mas-1999 description(complete)-duplicate.pdf

0093-mas-1999 description(complete).pdf

0093-mas-1999 drawings.pdf

0093-mas-1999 form-19.pdf

0093-mas-1999 form-2.pdf

0093-mas-1999 form-26.pdf

0093-mas-1999 form-4.pdf

0093-mas-1999 form-6.pdf

0093-mas-1999 petition.pdf


Patent Number 198115
Indian Patent Application Number 93/MAS/1999
PG Journal Number 30/2009
Publication Date 24-Jul-2009
Grant Date
Date of Filing 25-Jan-1999
Name of Patentee ALSTOM TRANSPORT SA
Applicant Address 38 AVENIE KLEBER 75116 PARIS
Inventors:
# Inventor's Name Inventor's Address
1 LIU RONG FAN 13 RUE JEAN MONNET, 64000 PAU
PCT International Classification Number H02P5/34
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 98 00773 1998-01-26 France