SIST EN IEC 62590-2-2:2026

SLOVENSKI STANDARD
01-oktober-2026
Železniške naprave - Elektronski močnostni pretvornik za fiksne postroje - 2-2.
del: Enosmerno napajanje - Krmiljeni pretvornik
Railway applications - Electronic power converters for fixed installations - Part 2-2: DC
Applications - Controlled converters
Bahnanwendungen – Leistungselektronische Stromrichter für ortsfeste Anlagen – Teil 2-
2: Gleichstrom Anwendungen – Gesteuerte Stromumrichter
Applications ferroviaires - Convertisseurs électroniques de puissance pour installations
fixes - Partie 2-2 : Applications de traction en courant continu - Convertisseurs
commandés
Ta slovenski standard je istoveten z: EN IEC 62590-2-2:2026
ICS:
29.200 Usmerniki. Pretvorniki. Rectifiers. Convertors.
Stabilizirano električno Stabilized power supply
napajanje
45.040 Materiali in deli za železniško Materials and components
tehniko for railway engineering
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 62590-2-2

NORME EUROPÉENNE
EUROPÄISCHE NORM August 2026
ICS 29.280
English Version
Railway applications - Electronic power converters for fixed
installations - Part 2-2: DC Traction applications - Controlled
converters
(IEC 62590-2-2:2026)
Applications ferroviaires - Convertisseurs électroniques de Bahnanwendungen - Leistungselektronische Stromrichter
puissance pour installations fixes - Partie 2-2: Applications für ortsfeste Anlagen - Teil 2-2: Anwendungen der
de traction en courant continu - convertisseurs commandés Gleichstrom-Zugförderung - Gesteuerte Stromumrichter
(IEC 62590-2-2:2026) (IEC 62590-2-2:2026)
This European Standard was approved by CENELEC on 2026-07-22. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62590-2-2:2026 E

European foreword
The text of document 9/3312/FDIS, future edition 1 of IEC 62590-2-2, prepared by TC 9 "Electrical
equipment and systems for railways" was submitted to the IEC-CENELEC parallel vote and approved
by CENELEC as EN IEC 62590-2-2:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-08-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-08-31
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 62590-2-2:2026 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60146-1-1:2024 NOTE Approved as EN IEC 60146-1-1:2024 (not modified)
IEC 60146-2 NOTE Approved as EN 60146-2
IEC 62590-2-1:2025 NOTE Approved as EN IEC 62590-2-1:2026 (not modified)
IEC 62924 NOTE Approved as EN 62924
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60071-1 - Insulation co-ordination - Part 1: Definitions, EN IEC 60071-1 -
principles and rules
IEC 60529 - Degrees of protection provided by enclosures EN 60529 -
(IP Code)
IEC 62590-1 2025 Railway applications - Electronic power EN IEC 62590-1 2025
converters for fixed installations - Part 1:
General requirements
IEC 62695 - Railway applications - Fixed installations - - -
Traction transformers
IEC 62236-5 - Railway applications - Electromagnetic - -
compatibility - Part 5: Emission and immunity of
fixed power supply installations and apparatus

IEC 62590-2-2 ®
Edition 1.0 2026-06
INTERNATIONAL
STANDARD
Railway applications - Electronic power converters for fixed installations -
Part 2-2: DC Traction applications - Controlled converters
ICS 29.280  ISBN 978-2-8327-1346-4

IEC 62590-2-2:2026-06(en)
IEC 62590-2-2:2026 © IEC 2026
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, symbols, and abbreviated terms . 7
3.1 Terms and definitions . 7
3.1.1 Semiconductor devices and combinations. 7
3.1.2 Line-commutated converters . 7
3.1.3 Self-commutated converters . 8
3.2 Graphical symbols . 8
3.3 Abbreviated terms. 9
4 System configurations . 9
4.1 General . 9
4.2 Purpose of converters . 10
4.2.1 AC/DC converters . 10
4.2.2 DC converters . 14
4.3 Basic characteristic of converters . 15
4.3.1 General. 15
4.3.2 Line-commutated converters . 15
4.3.3 Self-commutated converters . 16
4.3.4 Special considerations for combinations of AC/DC converters . 18
4.4 Interface to 3AC power network . 19
4.5 Interface to DC electric traction power supply system . 20
5 Design and integration . 20
5.1 System integration and coordination requirements . 20
5.2 Load requirements . 20
5.3 Data to be defined by the user's specification . 20
5.4 Mechanical requirements defined by the user's specification . 21
5.5 Data to be indicated by the manufacturer: . 21
6 Performance requirements . 22
6.1 General . 22
6.2 Protection . 22
6.3 Short-time withstand current . 22
6.4 Rating plate . 23
6.5 Main circuit terminals marking . 24
6.6 Losses. 24
7 Tests . 24
7.1 General . 24
7.2 Test specifications . 25
7.2.1 Visual inspection . 25
7.2.2 Test of accessory and auxiliary components . 25
7.2.3 Insulation test . 26
7.2.4 Operational sequence test . 26
7.2.5 Checking of protective functions . 26
7.2.6 Control function test . 26
7.2.7 Light load functional tests . 27
IEC 62590-2-2:2026 © IEC 2026
7.2.8 Load test . 27
7.2.9 Inherent voltage drop . 27
7.2.10 Temperature rise test . 27
7.2.11 Short-time withstand current test . 28
7.2.12 Power loss determination . 29
7.2.13 Audible sound. 29
7.2.14 EMC . 29
7.2.15 Harmonic measurements . 30
7.2.16 Power factor measurement . 30
7.2.17 Mechanical tests . 30
Annex A (informative) Power flow control strategies . 31
A.1 General . 31
A.2 Examples for DC side coordination of current versus voltage characteristics . 31
Annex B (informative) Calculation factors . 42
Annex C (informative) Test circuits for load tests . 43
C.1 General . 43
C.2 Test circuits . 43
Bibliography . 45

Figure 1 – General arrangement of AC/DC converters . 10
Figure 2 – Connection with separate transformers . 12
Figure 3 – Connection with combined transformer . 12
Figure 4 – Connection with combined transformer with taps . 13
Figure 5 – Converter with reversible valve device assembly . 13
Figure 6 – Common system configuration of stationary ESS . 14
Figure 7 – Configurations of DC converters . 14
Figure A.1 – Thyristor rectifier . 31
Figure A.2 – DC converter . 32
Figure A.3 – Diode rectifier with a DC converter . 33
Figure A.4 – Diode rectifier and self-commutated inverter . 34
Figure A.5 – Diode rectifier and thyristor inverter . 35
Figure A.6 – Diode rectifier and thyristor inverter . 36
Figure A.7 – Diode rectifier and thyristor inverter . 37
Figure A.8 – Diode rectifier and thyristor inverter . 38
Figure A.9 – Thyristor rectifier and thyristor inverter . 39
Figure A.10 – Self-commutated converter/inverter . 40
Figure A.11 – Self-commutated converter/inverter . 41
Figure C.1 – Test of a controlled rectifier or inverter . 43
Figure C.2 – Test of a reversible converter . 43

Table 1 – Graphical symbols. 8
Table 2 – Rectifiers, inverters and combinations . 11
Table 3 – Summary of tests . 25
Table B.1 – Voltage factors . 42

IEC 62590-2-2:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Railway applications -
Electronic power converters for fixed installations -
Part 2-2: DC Traction applications - Controlled converters

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 62590-2-2 has been prepared by IEC technical committee 9: Electrical equipment and
systems for railways. It is an International Standard.
This first edition partially cancels and replaces IEC 62589 and IEC 62590. This edition
constitutes a technical revision.
The text of this International Standard is based on the following documents:
Draft Report on voting
9/3312/FDIS 9/3328/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
IEC 62590-2-2:2026 © IEC 2026
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62590 series, published under the general title Railway applications -
Electronic power converters for fixed installations, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 62590-2-2:2026 © IEC 2026
INTRODUCTION
Semiconductor converters for traction power supply differ from other electronic power
converters for industrial use due to special electrical service conditions and due to the large
range of load variation and the particular characteristics of the load.
Controlled rectifiers supply a DC traction network from a three-phase power network using
controllable semiconductor valves. Inverters allow the recuperation of power from a DC traction
network into a three-phase power network. Reversible converters combine the functions of a
rectifier and an inverter.
DC converters are self-commutated converters for connecting the DC traction network to other
DC networks or storage devices.

IEC 62590-2-2:2026 © IEC 2026
1 Scope
This part of IEC 62590 describes functions and working principles, specifies requirements,
interfaces, and test methods for controlled converters for DC electric traction power supply
systems:
– AC/DC converters:
• rectifiers,
• inverters,
• combinations.
– DC converters.
The purpose of the converters can be a power connection to other power networks or energy
storages.
The common characteristic of this equipment is the possibility to influence the power flow in the
DC electric traction power supply system. The converters can be:
– line-commutated;
– self-commutated.
This document applies to fixed installations of the following electric traction systems:
– railway networks,
– metropolitan transport networks including metros, tramways, trolleybuses and fully
automated transport systems, magnetic levitated transport systems, and electric road
systems.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60071-1, Insulation co-ordination - Part 1: Definitions, principles and rules
IEC 60529, Degrees of protection provided by enclosures (IP code)
IEC 62590-1:2025, Railway applications - Electronic power converters for fixed installations -
Part 1: General requirements
IEC 62695, Railway applications - Fixed installations - Traction transformers
IEC 62236-5, Railway applications - Electromagnetic compatibility - Part 5: Emission and
immunity of fixed power supply installations and apparatus
IEC 62590-2-2:2026 © IEC 2026
3 Terms, definitions, symbols, and abbreviated terms
For the purposes of this document, the terms and definitions given in IEC 62590-1 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Terms and definitions
3.1.1 Semiconductor devices and combinations
3.1.1.1
rated current
I
Nd
value of a DC current a controlled converter is designed for, referring
to the DC electric traction power supply system
Note 1 to entry: All rated values of the components are derived from this value.
Note 2 to entry: A converter can have a rated continuous current and rated currents in conjunction with a duty class.
3.1.1.2
rated DC power
rated current multiplied with nominal DC voltage
Note 1 to entry: This value refers to DC electric traction power supply system side.
3.1.1.3
reversible converter
converter in which the direction of the power flow is reversible
[SOURCE IEC 60050-551:1998, 551-12-37, modified – Figure 1 has been omitted.]
3.1.2 Line-commutated converters
3.1.2.1
trigger delay angle
time expressed in angular measure by which the trigger pulse is delayed with respect to the
reference instant in the case of phase control
Note 1 to entry: With line, machine or load commutated converters the reference instant is the zero crossing instant
of the commutating voltage. With AC controllers it is the zero crossing instant of the supply voltage. For AC controllers
with inductive loads the trigger delay angle is the sum of the phase shift and the current delay angle.
[SOURCE: IEC 60050-551:1998, 551-16-33, modified – In the definition, “the” has been
deleted.]
3.1.2.2
commutation failure
failure to commutate the current from a conducting arm to the succeeding arm
[SOURCE: IEC 60050-551:1998, 551-16-59, modified – In the definition, “a” has been deleted]
IEC 62590-2-2:2026 © IEC 2026
3.1.3 Self-commutated converters
3.1.3.1
switched valve device
controllable valve device which can be turned on and off by a control signal
[SOURCE: IEC 60050-551:1998, 551-14-08, modified – In the definition, “a” has been deleted,
"may" has been replaced with "can".]
3.1.3.2
free-wheeling diode
diode parallel to a switched valve device in reverse direction fulfilling the purpose of a free-
wheeling arm
3.1.3.3
buck converter
direct DC converter providing an output voltage which is lower than the input voltage
[SOURCE: IEC 60050-551:1998, 551-12-33]
3.2 Graphical symbols
Table 1 lists all symbols used in this document. These symbols are based on symbols registered
in IEC 60617.
Table 1 – Graphical symbols
Symbol Explanation
AC/DC converter with optional indication of power
flow direction
SOURCE: IEC 60617-S00213:2001-07;
3~ 3~ 3~
IEC 60617-S01402:2001-09;
IEC 60617-S01403:2001-09
DC DC DC
IEC 60617-S00099:2001-07;
IEC 60617-S00100:2001-07;
IEC 60617-S01407:2001-10.
DC converter
DC
SOURCE: IEC 60617-S00213:2001-07;
DC
IEC 60617-S01402:2001-09.
DC converter with isolation between 2 electrical
circuits
DC
SOURCE: IEC 60617-S00213:2001-07;
DC
IEC 60617-S01402:2001-09;
IEC 60617-S01407:2001-10
diode rectifier (valve device) assembly
SOURCE: IEC 60617-S00641:2001-07;
Rec
IEC 62590-2-2:2026 © IEC 2026
Symbol Explanation
IGBT converter (valve device) assembly
SOURCE: IEC 60617-S00616:2001-07;
IEC 60617 S00621:2001-07;
IEC 60617-S00624:2001-07;
IEC 60617-S00641:2001-07.
thyristor converter (valve device) assembly
SOURCE: IEC 60617-S00654:2001-07.
Rec
Transformer with two windings
SOURCE: IEC 60617-S00841:2001-07.

Transformer with three windings
SOURCE: IEC 60617-S00844:2001-07.

Group of connections
SOURCE: IEC 60617-S00002:2001-07.

3.3 Abbreviated terms
3AC three phase alternating current
AC alternating current
ACTB apparatus for connecting the ESU to the DC bus
DC direct current
ESS energy storage system
ESU energy storage unit
IGBT insulated gate bipolar transistor
U power frequency test voltage for power frequency withstand voltage test
a
U nominal DC voltage
dN
U no load transformer voltage, valve side
v0
4 System configurations
4.1 General
The main purpose of controlled electronic power converters for DC electric traction power
supply systems is to establish an intended power flow. The power can flow from a 3AC power
network to the DC electric traction system or vice versa. This can also be a bidirectional power
flow to energy storages or other equipment using regenerated power.
IEC 62590-2-2:2026 © IEC 2026
4.2 Purpose of converters
4.2.1 AC/DC converters
4.2.1.1 General
The AC/DC converters connect a 3AC power network with a DC electric traction power supply
system as shown in Figure 1. Requirements from both networks shall be applied, see 5.3.

Figure 1 – General arrangement of AC/DC converters
4.2.1.2 Rectifiers
The purpose of rectifiers is to have a power flow from the 3AC power network to the DC electric
traction power supply system.
Controlled rectifiers operate on an adjustable characteristic curve in the current versus voltage
plane. This characteristic can be adjustable. Examples are given in Annex A. Limits can be
included.
Controlled rectifiers can be line-commutated or self-commutated.
A suitable duty class should be chosen from IEC 62590-1:2025, 5.7.2.
4.2.1.3 Inverters
The purpose of inverters is to enable a power flow from the DC electric traction power supply
system to the 3AC power network to improve the energy efficiency of the railway system.
Inverters operate on an adjustable characteristic curve in the current versus voltage plane. This
characteristic can be adjustable. Examples are given in Annex A. Limits can be included.
Inverters can be line-commutated or self-commutated.
The definition of a load cycle is appropriate in most cases, see IEC 62590-1:2025, 5.7.3.
4.2.1.4 Reversible converters
The purpose of the combination of a rectifier and an inverter is to enable a bidirectional power
exchange between a 3AC power network and the DC electric traction power supply system.
Reversible converters operate on an adjustable characteristic curve in the current versus
voltage plane. This characteristic can be adjustable. Examples are given in Annex A. Limits can
be included.
IEC 62590-2-2:2026 © IEC 2026
There is a broad variety of combinations using line-commutated and self-commutated
converters, see Table 2.
Figure 2 to Figure 5 show various possible combinations of rectifiers and inverters that can be
installed in a reversible substation. They can share the same transformer, the same control, or
the same filter.
Commonly used parts of the reversible converter are subject to a combined load requirement.
For the rectifier part a suitable duty class should be chosen. For the inverter part a suitable
load cycle or a suitable duty class should be chosen according to the application, see Figure 2
to Figure 5. This can result in an asymmetric load for 3 winding transformers in special cases
shown in Figure 3 and Figure 4.
IEC 62590-2-1 applies to the uncontrolled part of the reversible converter, if any, and this
document applies to the inverter part.
Table 2 – Rectifiers, inverters and combinations
Rectifier Inverter Reversible converter
3~ 3~ 3~
General symbol
DC DC DC
Inv
Rec
Rec Inv
Examples of associated
Rec
Inv
transformer and valve device
assembly
Rec Inv
Rec Inv
Rec
Inv
Rec/Inv
NOTE 1 The symbols represent typical valve devices used in the respective application.
NOTE 2 "Rec" indicates the use of a rectifier and "Inv" the use of an inverter.

IEC 62590-2-2:2026 © IEC 2026
Figure 2 – Connection with separate transformers
A reversible converter configuration can consist of a separated rectifier and inverter. Figure 2
shows such a configuration. Both can be connected to the same 3AC power network or to
different 3AC power networks. The function and design are as independent as possible.

NOTE Dashed symbols represent optional components to achieve symmetry.
Figure 3 – Connection with combined transformer
A reversible converter configuration can share the same main transformer. Such a configuration
is shown in Figure 3. In this case an additional transformer is used to adapt the inverter 3AC
voltage to the rectifier 3AC voltage. If a three-winding transformer with two traction side
windings is used, a single inverter or multiple inverters can be connected to one or both
windings equally. The main transformer shall be designed for both power flow directions.
IEC 62590-2-2:2026 © IEC 2026
NOTE Dashed symbols represent optional components to achieve symmetry.
Figure 4 – Connection with combined transformer with taps
Figure 4 shows a configuration with a combined transformer with taps. No additional
transformer is used for the adaptation of the inverter and rectifier voltage.

Figure 5 – Converter with reversible valve device assembly
Figure 5 shows the configuration of a reversible converter using a unique all-in-one reversible
valve device assembly associated with a unique transformer. In this case, the control for both
flow directions is integrated.
More than one traction side transformer winding can be used.
4.2.1.5 Reversible AC/DC converters for energy storages
The purpose of a reversible converter for an energy storage is to connect the DC electric traction
power supply system to an energy storage unit. In this case the ESU is a rotating machine.
IEC 62924 covers reversible converters for energy storage. The converter fulfils the function of
the ACTB.
The configuration is shown in Figure 6.
IEC 62590-2-2:2026 © IEC 2026
Load requirements are defined in IEC 62924.

NOTE DC bus means the DC traction power supply system in the addressed use case.
Figure 6 – Common system configuration of stationary ESS
4.2.2 DC converters
A DC converter connects the DC electric traction power supply system to another DC system.
This can be for example a capacitor or battery for energy storage purposes or a DC distribution
system. DC converters can also be used for controlling a wayside braking resistor for consuming
power of braking rolling stock.
NOTE A controlled wayside braking resistor is often called an automatic assured receptivity unit, or a braking
resistor unit.
Figure 7 shows the basic configuration of DC converters.

Figure 7 – Configurations of DC converters
Both sides of a non-isolating DC converter are part of the DC electric traction power supply
system.
An isolating DC converter separates the DC electric traction power supply system from another
system with different insulation coordination.
IEC 62924 covers energy storage. The converter is fulfilling the function of an ACTB.
See Figure 6.
For energy storage purpose load requirements are defined in IEC 62924.
For any other purpose a load class should be selected.
IEC 62590-2-2:2026 © IEC 2026
4.3 Basic characteristic of converters
4.3.1 General
Controlled converters have different basic working principles. A coordination between the
transformer and the valve device assembly is required. In most cases the transformer is part of
a filter circuit. The choice of the transformer main values has a major influence on the power
quality of the connected networks.
All controlled converters use voltage and current sensors. Their signals are processed and used
to create firing signals for the semiconductors. For all converters connected to a 3AC power
network, a synchronization with this network is necessary.
The user shall specify the complete operating range, together with the tolerance of the 3AC
network voltage. This information shall be used by the manufacturer to design the transformer
and the valve device assembly.
4.3.2 Line-commutated converters
4.3.2.1 General
The basic behaviour of line-commutated converters is broadly described in IEC 60146-1-1.
An application guide is IEC/TR 60146-1-2.
For basic connections, 6-pulse bridges or combinations thereof are used. The most common
types of line-commutated converters are those with 12-pulse connections. The basic
connections and calculation factors for uncontrolled operation can be taken from
IEC 62590-2-1:2025, Table 1.
NOTE The ratio between the direct voltage drop and the impedance voltage specified in IEC 60146-1-1:2024,
Table 10 have a slightly different meaning.
The DC voltage can be controlled by varying the trigger delay angle. A voltage versus current
characteristic can be established.
4.3.2.2 Line-commutated rectifiers
The transformer’s no-load voltage shall be chosen according to the required range of operation.
The transformer’s no-load voltage for a controlled rectifier is higher than for an uncontrolled
diode rectifier. The trigger delay angle reduces the DC voltage as described in
IEC TR 60146-1-2.
NOTE For the purposes of the rectifier, the trigger delay angle is in the range clearly below 90°. The trigger delay
angle depends on the point of operation and is usually between 60° and 5°. For practical reasons, a trigger delay
angle of 0° is not achievable as thyristors can only be switched on with a forward voltage.
The no-load transformer voltage is higher than the one for a comparable diode rectifier. With a
higher no-load voltage:
– the control range increases;
– the reactive power at the 3AC side increases;
– the DC harmonic content increases;
– the transformer power for the same traction load is higher;
– the 3AC harmonic content is higher at low current.
IEC 62590-2-2:2026 © IEC 2026
4.3.2.3 Line-commutated inverters
The transformer’s no-load voltage shall be chosen according to the required range of operation.
NOTE For inverters the trigger delay angle is higher than 90° and the cathodes are connected to the negative
polarity of the supply voltage. A practical range is between 130° and 165° including some reserve.
The expected worst-case operational situation should not lead to a commutation failure. This
worst case consists of the maximum operational DC voltage at the maximum DC current in
combination with the minimum expected operational 3AC power network voltage.
A commutation failure is a short-circuit and leads to an interruption of the inverter operation.
Only intended protection devices shall operate.
A commutation failure shall not lead to any damage of the inverter by design. Only the foreseen
protection devices should be reset. Neighbouring rectifiers should not be affected to guarantee
the availability of the power supply function.
The maximum allowable trigger delay angle depends on:
– the recovery time of the thyristor;
– the overlap angle as a function of the current;
– the commutation inductance provided by the transformer and the short-circuit impedance;
– the 3AC power network voltage;
– the transformer's rated no-load voltage;
– the DC operating voltage.
The choice of a proper traction side no-load voltage for the transformer is important for the
overall behaviour of the inverter. With a higher no-load voltage:
– the probability of a commutation failure decreases;
– the DC harmonic content is higher;
– the reactive power increases;
– the transformer power for the same current is higher.
In most cases a DC side inductor should be used to improve the operational behaviour in case
of a commutation failure and to reduce the DC harmonic current.
4.3.3 Self-commutated converters
4.3.3.1 General
Self-commutated converters are described in IEC 60146-2.
Self-commutated converters are characterized using switched valve devices that can be
switched on and off. The most commonly used valves are transistors and turn-off thyristors,
both with an antiparallel free-wheeling diode.
Self-commutated converters contain a major capacitor smoothing the DC side voltage. Together
with other components, they form a filter. Converters can be pre-charged in order to avoid
current surges.
IEC 62590-2-2:2026 © IEC 2026
4.3.3.2 AC/DC converters
A broad variety of connections are used in AC/DC converters.
The common main characteristics of self-commutated AC/DC converters are as follows.
– Use of free-wheeling diodes. The free-wheeling diodes are forming an uncontrolled rectifier.
The DC voltage is higher than the amplitude of the 3AC transformer traction side voltage.
– There is no fixed ratio between the 3AC transformer traction side voltage and the DC
voltage. The ratio is determined by pulse patterns and modulation methods. Safety margins
are used for the adaption to all points of operation.
– The converters can be operated in both directions even if not intended in some applications.
– The transformer is used for voltage adaption and electric isolation of the two networks
– The impedance of the transformer is used for power flow control and is part of a filter.
– Harmonic orders are specific for every converter type, on the DC side as well as on the
AC side.
– A major capacitance on the DC side is required for operation.
Pulse frequency, modulation method and number of parallel units define the harmonic orders
on the 3AC power network side as well as on the DC side. Coordination is recommended to
avoid frequencies used by the signalling system as well as resonance frequencies as far as
they are identified.
A self-commutated AC/DC converter can have additional control functions such as providing
reactive power for the 3AC power network side or active filtering. These optional functions shall
be specified if requested by the user.
4.3.3.3 DC converters
DC converters are mostly self-commutated.
DC converters are mostly reversible.
DC converters use a filter on the DC traction side.
Applications for energy storages shall be bidirectional. The free-wheeling diodes may carry a
current in the case of a DC electric traction power supply system short-circuit. A disconnection
device can be used for this case.
The power flow is controlled in both directions or in one direction only for wayside resistors.
For non-isolated DC converters boost or buck converters can be used.
Isolating DC converters consist of an inverter, a transformer, and a rectifier. They can be used
to connect the DC electric traction power supply system to other DC power systems. Both DC
circuits can have a different insulation level. In the terminology of power electronics, this type
is an indirect DC
...