Power- and machine-electronics 1914-1966
Citation for published version (APA):
Wyk, van, J. D. (1966). Power- and machine-electronics 1914-1966: a selected bibliography and review on the
electronic control of electrical machines. South African Institute of Electrical Engineers.
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Published: 01/01/1966
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P.O. BOX 61019 MARSHALLTOWN TRANSVAAL
THE SOUTH AFRICAN
INSTITUTE OF ELECTRICAL ENGINEERS
KELVIN HOUSE 2, HOLLAAD STAEET
JOHANNESBURG TRANSVAAL REPUBLIC OF SOUTH AFRICA
REPUBLIC OF SOUTH AFRICA
POWER- AND MACHINE-ELECTRONICS 1914-1966
"A selected bibliography and review on the electronic control of electrical machines"
By
J.
D. van Wyk, formerly with the Group on Electromechanical Energy Conversion,
Techno-logica! University, Eindhoven, Netherlands, and at present with the Group on Automation,
The South African Iron and Steel lndustrial Corporation, Ltd., Vanderbijlpark.
85 pages: 21
x
27 cm,
1 099 items entered,
20 figures.
This bibliography has been compiled by the author in the course of several years of research
work at the Technological University Eindhoven, Netherlands. The purpose was to collect
the relevant information from all available sourees published from the turn of the century
to 1966. A second volume covering the literature from 1966 to 1970 is in preparation.
Brief summary of contents:
Historica! notes and evaluation.
Classification of the fields of power-electranies and machine-electronics.
List of journals cited in the bibliography.
Bi bliog ra ph i cal i nformation, classified systematically.
Alphabetical author index.
The bibliographical information has been arranged chronologically within each defined
systematic class. This facilitates retrieval and gives an indication of the subject development.
Copies of the Bibliography can be obtained from the lnstitute at the above address.
P.O. BOX 61019 MARSHALLTOWN
TRANSVAAL REPUBLIC OF SOUTH AFRICA
THE SOUTH AFRICAN
INSTITUTE OF ELECTRICAL ENGINEERS
KELVIN HOUSE 2, HOLLAAD STREET
JOHANNESBURG TRANSVAAL REPUBLIC OF SOUTH AFRICA
POWER· AND MACHINE· ELECTRONlOS 1914 -1966
A selected bibliography and review on the electronic control of electrica/ machines
By
J.
D.
Van Wyk*
*
Formerly with the Group on Electromechanical Energy Conversion, Technological
University Eindhoven, Netherlands, and at present with the Group on Automation,
lscor, Vanderbylpark.
CONTENTS
1
Summary
5
2
lntroductory remarks
5
3
Historical notes
5
4
Classification of the fields of power electranies and
machine-electranies
16
5
Practical comments concerning the bibliography .
19
6
Bibliography
6.0
List of Journals
22
6.1
General published work
25
6.2
Power electronic frequency changers
29
6.3
PEREM-systems or machine electronic systems
6.3.1
Group I systems (Frequency changers in combination
with induction and synchronous machines)
48
6.3.2
Group 11 systems.
(a) Rotor regulated induction machines .
54
(b)
Voltage regulated machines
55
6.4
Semiconductor power switches
63
6.5
Alphabetical list of authors
76
1
SUMMARY
This work contains a bibliography concerning
power electranies and machine-electranies or
PEREM-systems. In a short historica! introduetion
some aspects of the development of electronic
power switches, circuits and some electrical
machine regulation systems are outlined.
In this way the history of the mercury-arc
ree-tifier and the thyristor is traced. lt is attempted to
ascertain the origin of the idea of building an
inverter, of using it tor electrical machine control,
of electronic choppers, of electronic voltage
regu-lation of electronic machines and of electronic
rotor controL
Classification of the fields of power and
mac-hine electranies is discussed briefly, and some
practical comments on the bibliography given.
2
INTRODUCTORY REMAAKS
Rotating electrical machines have a relatively
long history compared to some other branches of
electrical engineering. For the duration of this
historica! development schemes have been
de-vised to change the relationship between torque
delivered by, and mechanica! speed of, a
par-ticular machine. The relationship between these
two mechanica! variables of the machine, being
determined by the electrical parameters of the
machine, the parameters of the supply and the
type of machine, is of a predestined farm tor a
specific machine operating trom one of the
nor-mally available supplies. The motivation tor the
above mentioned search has been the
tact
that the
requirements of the driven loads will nat always
match the predestined relationship between
torque and speed. Practical execution of the
theoretica! schemes suggested to achieve this end
did nat always follow so easily and the eventual
widespread practical application of the solutions
to the problem was in many instances prevented
by the intricate combination of economics,
reliability, efficiency, power factor, speed range,
regulation, simplicity, ease of control and
main-tenance, power-to-weight ratio, obsoleteness
and the many other factors determining the
prac-tical future of a salution to a problem in
engineering practice.
During this development it is interesting to
note the interest stimulated by every new device
showing promise tor the control of electrical
machines. The enthusiasm with which the search
tor changing the torque-speed relationship has
always been persecuted may be experienced even
in 1896 in the work of Görges
1where he reports
on the first observations concerning the
Görges-phenomenon.
The methods of achieving this much sought
after result by using power-electranies farms the
basis of this study. Apart trom these solutions,
however, the years have presented a rich array of
methods to change the torque-speed relationship.
An interesting and comprehensive survey has been
presented by Laithwaite
2,indicating the extent of
the demand tor simple variabie speed drives.
When the study of the subject of
machine-electranies was cammeneed by the author no
bibliography on this subject could be found. This
resulted in the present work. The bibliography
does nat pretend to be comprehensive. The extent
of the technical-scientific literature at present is
such as to almast exclude the possibility of one
person compiling a comprehensive bibliography
in the span of a tew years. The work does,
how-ever, pretend to present the growth of the subject.
3
HlSTORICAL NOTES
3.0 General remarks.
3.1 The development of the different switching
devices.
3.2 Power electronic frequency changers.
3.3 The development of machine electronics.
3.3.1 Electronic commutators.
3.3.2 Rotor control of induction machines.
3.3.3 Voltage control of machines by power
electron i es.
3.0
General remarks
The history of the control of electrical machines
by switching devices appears to consist of
alter-nating periods of supremacy of mechanica! and
static (gaseous or solid-state) switches.
The aidest known switch used in the control
of electrical machines is the mechanica!
commu-tator. Subsequently the gaseaus valves showed
promise tor generating the switching functions
necessary to control machines. These devices had
some disadvantages and at a time it appeared
that the mechanica! metallic rectifier (a modified
commutator!) was the future promise. Almast
simultaneously it was succeeded by a device
developing in parallel-the transductor or
mag-netic amplifier. The era of the semiconductor
switches then dawned-an era trom which we,
being still concerned in its development, are able
to derive but little historica! perspective.
Numerous works have been published and
circuit configurations and methods of regulating
electrical machines electronically worked out or
suggested in the past. lt has therefore become
extremely difficult to ascertain the origin of most
of the circuits and methods of control employed
at present in machine electronics. The aim of this
historica! introduetion is to present the knowledge
acquired on these matters during compiling of the
bibliography in an attempt to clear up some of
these aspects.
3.1 The development of the different
switching devices
lt has already been pointed out that the first
switching device used in rotating electrical
mac-hines was the mechanica! commutator.
lt
may be
said that this development, through many forms,
took place during the nineteenth century. This
is evident when one compares the cammutators
employed by Page in the years 1840, in his
elec-trical imitation of steam engines, to the rotating
cammutators used subsequently in direct voltage
machines.
Although interesting from a historica! and
educational point of view, this development will
not be traeed here.
The first static non-linear device discovered was
the crystal detector by Braun in 1874 in
Stras-bourg3•
4•
Much later, after 1920, this was
ex-tensively used in the radio field, but was never
developed to power levels applicable to electrical
machines. The selenium rectifier of Presser
(1925)
5,and the cuprous oxide rectifier of
Grondahl (1926)
6,
were used in the power field
with good results. As far as a controllable
switching device is concerned, the grid controlled
mercury-arc-rectifier was the only predecessor of
the present-dav controllable semiconductor
swit-ching devices. Therefore the development of this
device will now be considered.
Although the practical development of this
device did not come into being before nearly a
third of the twentieth century was past, it is
interesting to note that the physical pricinples
underlying the behaviour of
mercury-arc-recti-fiers had apparently been recognised in 1882 by
Jemin and Meneuvrier
7•They gave an account of
the property of an electric are established between
mercury and carbon electrodes, mentioning that
the current will flow in one direction only. In
1889 Fleming investigated the property of
uni-lateral conductivity of the electric are in air, while
between 1894 and 1898 Sahulka described the
results of identical investigations pertaining to
atmospheric arcs between mercury and iron or
carbon electrodes.
All these experiments were conducted under
atmospheric conditions. In the years 1890-1892
Arons made the first vapour lamps by enclosing
the are in an evacuated vessel. Apparently a
rectifier based on the unidirectional conduction
principle of the mercury are emerged around 1900
when Cooper- Hewitt took up the manufacture of
these lamps on a commercial scale. The stage was
then setfora gradual development of the
mercury-arc rectifier as a switching device, reaching general
application in all types of service probably after
1925.
In 1903 Cooper-Hewitt indicated the possibility
to control the current are in a mercury rectifier by
means of grids between anode and cathode, and
even mentioned the possibility to apply impulses
to these grids, but the development of the
con-trolled rectifier did not follow immediately
7 .In
1914 Langmuir in the U.S.A. indicated the
possi-bility of cantrolling the time of starting of the
current in a thyratron tube by means of a grid in
such a way that the average value of the current
changed at will. He employed a steady grid
potential of variabie magnitude. In subsequent
years other techniques for grid control, including
phase control by an a.c. potential on the grid, were
developed.
lt was not befare 1928 that the first practical
mercury are controlled rectifier seems to have been
developed by Langmuir and Prince
8.Shortly
afterwards the application of control grids tosteel
tank mercury-arc rectifiers was undertaken by
Brown- Boveri, Siemens-Schuckertwerke and the
Allgemeine Elektrizitäts Geselischaft almast
simul-taneously. When the Second World Power
Con-ference was held in Berlin in 1930 these three
firms staged comprehensive displays of the new
technique in their laboratories
7•Thus, 48 years
after the first principles appear to have been
realised, the controlled mercury-arc rectifier was
ready for large-scale practical application.
The controlled mercury-arc rectifiers had some
severe shortcomings such as being fragile, bulky,
expensive and prone to "arcing back". In many
cases the advantage of having a piece of static
apparatus was more than off-set by these
dis-advantages. Subsequently the mechanica I metallic
rectifier received an increasing amount of
atten-tion. Much development work along these lines
was done by Koppelmann
9,
being one of the ma in
exponents of this technique. Even at present it is
ditticuit to judge whether this device would have
found widespread practical application as a
ree-tifier finverter if the magnetic amplifier did nat
appear. At the time of the Second World War the
principles underlying the functioning of the
transductor had been known for a long time, yet
only during these and subsequent years did it
come to full development.
lt is at present well known that early in the
1950's the junction transistor foliowed the
pioneering workof Bardeen, Brattain and
Shock-ley in semiconductor devices at the Bell
Labora-tmies in the U.S.A.
10.Furthermore it is extremely
interesting to note that in the very fjrst
compre-hensive work to appear on the p-n junction
transistor in 1951, Shockley and his co- workers
mention the p
1-n
1-p
2-n
2structure with an
elec-trode attached to the p
2-region
10-a structure we
know as a thyristor at present. Yet it appears that
the importance of this device when used as a
switch was nat realised. Following the work of
Shockley, Ebers developed the now famous two
transistor analogue to indicate what type of
characteristics might be expected trom such a
p-n-p-n device
13.
Although silicon p-n junction devices as power
rectifiers gained an increasing importance in the
subsequent years, the matter of a controlled
silicon rectifier rested until 1956, when Moll and
his associates at Bell saw the promise of the tour
layer structure
12.
Yet the p-n-p-n switch was still
.,at widely appreciated, and the actual initiative
,,f building a high current switch and introducing
lt
to the practical application field should probably
ne credited to York of the General Electric
~:ompany13.He was awara of the workat Bell, and
. ·Nith his co-workers built the first high current
version of the thyristor or p-n-p-n switch in 1957.
This touched off a world-wide investigation that
has continued to this day. Although it is ditticuit
to judge history oversoshort a span of time (only
ten years have elapsed since), it appears that if
a birth date for the practically useful thyristor has
to be named, it should be 1957-1958. Thus, ten
years after the first work on useful semiconductor
amplifiers and switches was done by Bardeen,
Brattain and Shockley, the new device was ready
to conquer the power field. lt must be remarked
that the invention of the thyristor came at an
extremely opportune moment, due to the high
degree of development already reached at that
time in the field of transistor-logic and amplifying
circuitry.
The thyristor stimulated study of multi-p-n
junction semiconductor devices during the past
ten years, and this has resulted in a family of
switching devices of a remarkable degree of
sophistication, yet at present still in their infancy.
At present the most promising, the "triac" or
bilateral triode switch, appears to be due to
workers at the General Electric Company again
14 .Other promising devices include the bilateral
diode switch ("diac"), gate-turn-aft-switches
(G.T.O.'s), light activated thyristors (Lasers) and
some other tour terminal devices. At present the
thyrislor is employed almast exclusively in
machine electronics, and therefore the historica!
development of these other devices will nat be
discussed.
Although, as remarked previously, the history
of the semiconductor power switch is very brief,
it is already possible to make two important
observations.
(i) Compared to the rate of development of
previous switches, the development of the
new family of devices is rapid.
(ii) Due to these circumstances one must be
extremely caretul in making forecasts with
regard to the application of these switches.
Pessimistic views as to the maximum
attain-able voltage ratings of these devices saw the
value of 600V generally obtainable on devices
tour years ago as near the limit, yet at present
thyristors with a rating of more than 3000V
are on the market.
lt is therefore worthwhile to consider every
possible application of these devices in
machine electranies with a view to the future.
The academica! thoughts of today build the
practical drives of tomorrow.
3.2
Power electronic frequency-changers
The role of power electronic frequency changers
in machine-electranies is primary. Normally
available supplies are of a fixed frequency. To
obtain other frequencies trom this
single-fre-quency supply, a non-linear device is incorporated
in the system. The spectrum arising out of this
may be used in all its components or in one
only-depending on the application. However,
machine-electronic systems are energy processing, and
therefore the losses in the non-linear element
should be small, or zero if possible, in order to
obtain a high efficiency. The ideal switch answers
to this description. When thinking about "high
frequency" of operation and adverse operating
conditions dependent on external influences, it
becomes clear why electronic devices have
always been sought. The development of these
types of devices known today has been examined
in 3.1, and some remarks about the historica!
development of the circuits using these will now
be made.
Soon after the practical value of the mercury
vapour tube as a rectifier was realised,
investiga-tions into its circuit implicainvestiga-tions started (see for
instanee:
15).
In the following years till 1930 most of the
u neontrolled rectifier circuit configurations known
today were developed. These circuits are well
known.
Although actual practical controlled
mercury-arc rectifier units were not developed before 1928,
the first inverter dates trom 1925. The term
"inverter'' is due to D. C. Prince of the General
Electric Company in the U.S.A.
16•
lnteresting is the
S.M. Synchronous machine
following comment of the editor of that journal
at the head of the abovementioned artiele: "In
the September, 1924, issue of this magazine, Mr.
Prince contributed an artiele dealing with the
tube-rectifier and its characteristic waveforms. In
the present contribution the author has taken the
rectifier circuit and inverted it turning in direct
current at one end and drawing out alternating
current at the other.
The new apparatus, consisting of pliotron
tubes, transformers, reactances etc. is known as
the "lnverter" and offers a means of converting
direct current into alternating current without
the u se of any rotating machines."
From this quotation the origin of the word
"inverter'' still in use today is obvious-it was
meant to indicate a circuit doing the inverse of
what a rectifier does.
G Generator supplying direct voltage
P1, P2 : "Piiotron" tubes
T: I nverter transfarmer
Fig. 1. The inverter circuit of Prince16
The switching elements used by Prince were
vacuum tubes. Due to the fact that he employed
15 kV as operating voltage, the voltage drop over
the tubes was not important. The problem of
supplying reactive power to the system was
over-come by using a synchronous machine in the
output. lt should be noted that the contiguration
of the switches in the above system is already of
the parallel type.
The parallel-configuration is sometimes referred
to as the "Wagner-inverter", yet it would probably
be more truthful to refer to it as the
"Prince-inverter", since Wagner worked much later
17•
After Prince, Sabbah
18and Tompkins
54also
dis-cussed the characteristics of parallel and series
inverters.
Following the invention of the steel tank
con-trolled mercury-arc rectifiers in Europe at the
beginning of the 1930's, an enormous activity in
the field of inverters was initiated. This may be
verified by consulting the histograms of the
bibliography. These developments concerned
many aspects of the problems associated with
inverters. lt is probably worthwhila to note two
further interesting points regarding development
of these circuits. The first inverter proposed by
Prince needed a synchronous machine in the
out-put to furnish the reactive power. This was the
case with all inverters proposed afterwards-in
absence of a machine they could not handle
reactive power. In 1932 Petersen
19proposed the
use of two additional valves (S
2and S'
2fig. 2) in
the parallel inverter to handle reactive power. lt is
possible to extend this principle also to systems
having more than one phase. Petersen still used
an additional voltage E for commutation-purposes.
Tompkins
54apparently first employed
commuta-tion capacitors in order to obtain a self-contained
inverter ("selbstgeführte Wechselrichter") (Fig.
3(a) ). This may be regarded as another major
advance in the art of inverters.
The use of the commutating capacitor had one
unwanted effect-it discharged over the
trans-farmer winding, impairing commutation.
lncor-poration of the decoupling diodes D
1and D
2RL = load resistance
LL = load inductance
E: Commutation EMF
(Fig. 3) eliminates this effect. As far as it is
possible to ascertain at present, this salution is
of a relatively recent date. According to Ward
20these diodes are due to B. Y. Umarov and were
first described by Hamudhanov
21•
On the other hand these diodes were used quite
independently by de Zeeuw in 1961 at the
Technological University of Eindhoven
22•
In the literature befare 1940 Tröger drew
inverter diagrams with mercury are rectifiers in
series with the commutation capacitors in a
review assay
23 •s•
1S" S' ,, S
2,S'
2 gas tubes T: lnverter transfarmer L: Commutating inductances•
2Fig. 2. Proposed inverter circuit of Petersen19 with "Petersen valves".
c
1 2 (a) S 1 , S 2 : Controlled rectifiers D 1, D 2 : Decoupling diodes (b) C: Commutating capacitor L: Commutating inductance T: lnverter transfarmerFig. 3. Development of parallel-inverter with decoupling diodes21
Unfortunately the references given by Tröger
are inadequate to be able to deduce the original
function, and therefore this question will most
probably have to remain unsolved for the time
being.
The frequency changing circuits developed in
the period of the controlled mercury-arc rectifier
were limited in their complication by the cast,
speed and size of these valves. The thyristor is
much smaller, tasterand already cheaper, and has
therefore started off a development of extrenely
complex circuits, with a corresponding increase
in possibilities tor application. To attempt to
trace the historica! development of these circuits
involve much detail and may safely be left to the
specialized student of these units. At present no
comprehensive survey of these circuits exists in
the literature, the existing works being of limited
scope (see tor instance
24).
3 PHASE SCFPLY,
Another type of frequency changer that has
known a remarkable development is the so-called
cycloconverter. The terms "cyclo-conversion" and
"cycloconverter" were invented by Rissik
7in
the years befare 1935 (see Fig. 4). The main
disadvantage of this type of cycloconverter was
the non-sinusoidal output voltage more or less
resembling a trapezium.
To eliminate this, the envelope cycloconverters
were developed. The Löbl-cycloconverter was of
a synchronous type, having a definite phase
relationship between the two
systems~5.The Krämer-cycloconverter
7• 26was
asynchro-nous, yet still had a fixed ratio of output to input
frequency.
Credit tor the development of a continuously
variabie grid-controlled cycloconverter goes to
Schenkel and van lssendorff
27• 28•This type of
circuit contiguration is again used to great
advantage in modern thyristor circuits.
s::;GL~ P'iAS;è S\"STD!
Fig. 4. Original cycloconverter circuit of Rissik, 1935'.
3.3
The development of
machine-electronics
Although the field of "machine-electronics"
has yet to be defined (Section 4), let it suffice at
present to say that it concerns the systems
con-sisting of rotating electrical machines and power
electronics. In this case power electranies is a
loosely defined entity, indicating electronic
cir-cuits in which the main tunetion is nat
informa-tion processing, but supplying power to some or
other system to be controlled. The level of this
power is nat defined, and may even be
micro-watts. lt will be realised that this present
definition is intuitive rather than exact.
ldeas to use electronic elements to control,
reg u late or augment electrical machines appear to
have been put into practice tor the first time
during the years immediately befare and after
1920. lt is possible that these contributions may
nat be characterised as machine-electranies as
it is known today, yet it may be considered as the
very beginning of the subject.
In the year 1917 Bolliger came upon the idea
of a "high-voltage" d.c. machine (published
1921) in which the substantial part of the
com-mutator action is executed by a mercury-arc
rectifier. Ta quote Bolliger: "Der Kommutator
arbeitet lediglich als ein bei leerlaufenden Phasen
kontaktmachender Spannungsschaltapparat, ohne
jede Stromwendung unter den Bürsten. Der
Gleichrichter hingegen wirkt als ein durch dié
Betriebsphasenspannungen gesteuerter
Strom-wendeapparat .... "
29.+
w
..
M.G. Mechanica! commutator M.R. Mercury-arc rectifier
From the previous paragraph and from Fig. 5
it may be gathered that by connecting the valve
in series with a mechanica! switch he was able
to obtain the characteristic of a controlled
rectifier. This is the more remarkable, since at that
stage the controlled mercury-arc rectifier still
belonged to the future. The high voltages in the
reverse direction, and the actual commutation
were the responsibilities of the rectifier. This
indicates that Bolliger had already fully realised
the necessity for a static electron ie commutator;
but did nat yet have the necessary circuit
elements. His appropriate camment on his own
work was: "Einen Anfang zu etwas dass noch
nicht ist".
H.R.
W ,-W 6 Machine armature windings
F.W. Field winding
Fig. 5. lllustration of the principle of the "high-voltage" d.c. machine of Bolliger.
Van der Bijl described control systems for
d.c. generator current and voltage in 1920
55,attributing=the=origin of the ideas to Wold.
In these systems a vacuum triode ("audion")
was connected either in series or in parallel with
the field winding of the generator, the essential
control element.
R
A: Audion, G : d.c. generator, R 1 : Current resistance,
Rg: Grid resistor, FW: Field winding
Fig. 6. Schemes presented by van der Bijl
In the years before 1930 Voorhoeve in the
Netherlands investigated possibilities to control
generator voltages by electronic means. Contrary
to the work reported by v. d. Bijl, he employed
vacuum diodes, the heating current being the
variabie (Fig. 7). This is understandable, since
at that time the grid controlled mercury-arc tube
had not yet been made widely known by Langmuir
and his associates.
Later work by the same group included the use
of vacuum triodes, but was overshadowed by the
D
R1
F
tast developing control schemes by
grid-con-trolled mercury-arc rectifiers
30, 31.After the invention of the controlled gaseous
valves an increasing amount of attention was
given to the study of machine-electronic
sys-tems. With reference to the histograms included
in the bibliography it is evident that there exists a
definite shift in time between the research work
devoted to power electranies and
machine-electron i es.
(a) + ç---~ G 1 : A.v. generator D: Vacuum diode F: Field winding T 1 : Current transfarmer T2:
Voltage transfarmer G 2: D.v. generator3.3.1
Electronic cammutators
Reference has already previously been made
to the fact that the electronic switches may be
used to perfarm the same tunetion as mechanica!
switches in conjunction with an electrical
machine. One of the initial ideas that sprung from
the availability of the controlled mercury-arc
rectifier was to build an electronic commutator.
The first machine to use an electron
ie commutator
was the machine of Kern-a now famous
example
32.In fact, Kern suggested various
con-figurations, one being shown in Fig. 7. In the
years befare 1940 these types of machines were
studied by many workers, and were originally
primarily intended for traction purposes.
Although it was applied on the European
con-tinent and in the U.S.A. to a certain extent
33,
the
thyratron or controlled mercury-arc commutator
motor never attained true widespread practical
application. In some cases smaller motors were
driven by vacuum-tube oscillators or by thyratron
relaxation oscillators, but all these applications
remained special solutions to a limited number of
problems. The motors used were mostly of the
synchronous type.
lt is understandable that since the thyristor
has come of age, the thyristor commutator motors
have received renewed attention. The
character-istics of this element makes universa! application
possible.
grid control
W1 .. •12 machine stator windinga L . - - - '
R rotor and field winding
T transtormar
CR ::cntrc::.:~.; r~etifier
Fig. 8. Thyratron-commutator machine proposed by Kern32
•
In most cases the modern technology tends
towards a separate inverter and motor, and not
towards using the motor windings as part of the
inverter. This approach may change with time,
however.
One of the ideas being worked out at present
is the use of thyristor-frequency changers in
conjunction with squirrel-cage induction
mac-hines for electric traction purposes
34• 35•
This idea
has been considered in the past, but rejected
36.The reason for the rejection of this proposal in
1940 was the enormous amount of equipment
needed, it being impossible to transport it aboard
an ordinary locomotive. Thyristors are relatively
small in size and eliminate this problem, as has
been illustrated by the present experiments. The
ma in hazards besetting the application of this type
of traction at present seem to be economics and
reliability
The interest in electronic cammutators
stimu-lated anew by the thyristor have apparently
stimulated the use of transistors for the same
tunetion in small machines. This is the inevitable
conclusion, as it was not befare 1962 that this
type of electronically commutated machine
re-ceived serious attention
38,although switching
transistors were available years before. lt
origi-nated in the U.S.A. and later spread to Germany
37•
At present the future for these devices appears
promising.
3.3.2
Rotor regulation of induction
machines
Compared to direct current machines wound
rotor induction machines are relatively cheap and
it is therefore interesting to investigate all
pos-sihilities to control them. Electronic regulation in
the rotor current of these machines has only
recently received some worthwhile attention,
however.
This may be verified by examination of the
appropriate histogram, and may be ascribed to
the high voltage drop over the previously
available electronic devices, as well as to their
cast and size.
The first work on electronic rotor control of
induction machines concerned electronic
Scher-IM: lnduction motor
RT 1, RT 2 : Rectifier transfarmers
bius ascades. Due to the considerations
men-tioned in section 3.3.1 the application was only
interesting tor larger machines. In 1939 Stöhr
56• 57
apparently proposed the first electronic Scherbius
cascade, indicated in Fig. 9. Subsequently Hölters
(1943)3
9also investigated this type of system.
To his system the rather unfortunate name of
"Asynchron-Stromrichtermotor" was given. This
name has si nee been used to indicate a nother type
of system, i.e. that of a variabie frequency
inverter feeding an induction motor, the motor
windings being part of the inverter.
CHR
M R: Mercury-arc rectifier
CMR: Controlled mercury-arc rectifiers Fig. 9. Electronic Scherbius cascade of Stöhr.
The magnetic amplifier was, and still is, applied
with good results to this type of control
2but it is
only during the last decade after the development
of the thyristor, that this type of control has
received increasing attention in the farm of
elec-tronic switching of the rotor current, notably in
Germany (See for instanee
40).Development of
silicon rectifiers renewed the interest in systems
consisting of wound-rotor induction machines
and frequency converters in the rotor4
1,
while
thyristors holds the promise of making this drive
economie and
campact-also
for
smaller
machines.
3.3.3
Voltage regulation of machines
by
power electranies
The systems employing control of the applied
voltage of the machines by electronic methods,
are to be divided mainly into two categories:
induction machines having antiparallel switches
on the stator side, and d.c. machines with
armature voltage controL (In some instances d.c.
machines are also operated with electronic field
control as already mentioned). The d.c. machines
having armature voltage control may be fed
trom
either an a.c. or a d.c. system.
Control of d.c. machines fed by three phase
or single-phase a.c. systems drew attention after
the introduetion of the controlled mercury-arc
rectifier in 1928. lt was realised that this offers
the possibility to regulate the main current in the
motor4
2,and was apparently first extensively
investigated by Schilling
43.
As is evident from the
histograms, interest in these types of control
increased steadily through the years. Later
attention was devoted to constructing static
Ward-Leonard drives in this way. (See for
in-stance
30).Semiconductor switches increased
the possibilities (see histogram) and it may be
expected that the present popularity of this type
of semiconductor controlled drive will still
con-tinue for a considerable time.
Apparently the inventor of armature voltage
control of d.c. machines by pulse modulation, the
so-called series chopper-was Blaufuss in 1940
44•
The problem was to obtain a mechanica! ar
elec-tronic switch that could be operated reliably and
tast
enough to achieve this controL lt taak years
befare the idea of Blaufuss was taken up again.
Gutenbaum did theoretica! work on this type of
h 11
l
JMR
F.T.: Field Transfarmer M.T.: Ma in Transfarmer MR: Mercury rectifier rproblem
4-"· 46
but it is nat clear whether a system
was practically realised. The first practical
realisation of this scheme by electronic means
appears to be due to Jones
47in the U.S.A. and to
Abraham, Heumann and Koppelmann
48in
Ger-many, the two groups working independently,
and employing thyristors as switches.
lt is interesting to note that the electronic
L
CMR: Controlled mercury rectifier
L:
M:
Switching inductor Direct cutrent motor
Fig. 10. Original scheme for a.c. fed d.c. motor investigated by Schilling'".
chopper as employed by these groups was
discussed in 1932 by Tompkins in relation to the
parallel inverter
54•
These types of power-electronic systems have
since developed rapidly-especially with respect
Re Laad resistance Re: Charging resistance Cc: Commutating capacitor
T: Thyratron
to the circuit improvements possible. Electronic
choppers reg u lating series direct voltage machines
is one of the most successful machine-electranies
systems at present, finding widespread application
tor
low loss control in traction circuits.
Th: Main thyristor
Thc: Commutating thyristor
Sc: Commutating switch
Regulation of alternating voltage and current
by using electronic switches in antiparallel
con-tiguration appear to have foliowed the same line
of development. The idea is not new, and due to
Lenz
4 9(Fig. 12) who published it in 1933.
Previously the idea of using grid controlled
mercury valves tor current control had been used
in welding equipment
50,but in a one-sided
configuration. Strangely it does not seem to have
been worked out further for the control of
squirrel-cage motors, although the idea was
later applied in conjunction with magnetic
amp-lifiers51. The possibility of using thyristors has
renewed the interest in this type of control
recently
52,
and the development of the triac will
make this type of drive still more compact and
robust, and in the end much cheaper.
CM R I• CM R, Controlled mercury-arc rectifiers
T 1 Transfarmer
RL
LL LoadFig. 12. Antiparallel system investigated by Lenz (1933).
4
CLASSIFICATION OF THE FIELDS OF
POWER-ELECTRONICS AND
MACHINE-ELECTRONICS
4.1 Definitions of power electranies and
machine electranies
Under normal conditions the accent in an
electronic system may fall on the information
processing aspect or on the power processing
aspect, quite apart trom the power levels involved.
In the electronic systems used in combination
with electrical machines, these two functions are
both present. lt will be postulated here that part
of the system in which the accent is on
intar-mation processing be called the inforintar-mation-
information-electronics and the other part of the system
correspondingly the power electronics. lt will be
realised that it is not in all practical systems
possible to distinguish between these two
tune-tions explicitly, especially in the case of
micro-motors with electronic commutators
37,yet it
remains advisable to make the distinction with a
view to the classification system being developed.
The word "machine-electronics" in itself is
misleading, since as such it merely means
electranies used with a machine, not necessarily
an electrical machine, and it is specifically
inten-ded to indicate a system consisting of an electron
ie
part and a rotating electromechanical transducer
or rotating electrical machine. The use of this
word is only justified since it farms a handy
acronymn for sarnething that may be specified
as a "Power- Electron ie Rotating
Electromechani-cal transducer system", from which the more
appropriate acronymn PEREM-system may be
formed.
From the preceding it is clear that a
machine-electronkor PEREM-system consistsof two
sub-systems-the electranies and the rotating
elec-trical machine. Such a system is used instead of
a singular electrical machine in order to be a bie to
establish a torque-speed relationship differing
from the predestined farm for the machine when
connected to a "normal" supply. lt may be
remarked that mostly the information-electronics
is left out of the analysis of the system, and the
subsystem electranies (see Fig. 13) becomes the
power electronics. In Fig. 13 the dotted line marks
that part of the system most commonly referred
to, and being studied as machine-electronics.
Since a mutual influence exists between the
componentsof the system, the subject of machine
electranies does not merely combine the
"clas-sica!" knowledge of power electranies and
electrical machines.
Electrooie rotating electromechanical trans Subsystem Electronica
--- ---,
in formation El6ctronics Electronica 1 - - - -.... Subsyetea rotating electromecha-nical transducer-
-
-
-
- -
-
-
--
- -
-
...---
-
--- - -
-
- - - --
--·
Fig. 1 J. Electronic-rotating-electromechanical-transducer-system.As definitions may therefore be considered:
Power electranies concerns itself with the
study of that part of an electronic system in
which the accent falls on the processing of
power necessary at the output rather than on
information. The definition is nat coupled to a
certain absolute level of power, but is relative.
Machine electranies or study of
PEREM-systems concerns itself with the study of
systems consisting of power-electranies in
con-junction with rotating electromechanical
trans-ducers (or rotating electrical machines).
Prac-tising of this branch of electrical engineering has
as its objective the alteration of the "traditional"
torque-speed relationship of a specific type of
machine.
4.2 Brief indication of a classification
system for PEREM-systems
lt is possible to employ various different
approaches to classify the different type:; . <;Jf
machine-electron ie systems. One of the
poss1bi11-ties is to use the power relation in the whole
electrical system. This approach will be used here.
Befare considering these power relations it is
necessary to make certain agreements regarding
the electrical machines. The stator and rotor
carry windings of m-phases and 2-p poles.
Circular rotating magnetic fields of angular
velocity of
Ü)s/P
and
Ü)r/P
with respect to the
stator and rotor bodies are set up when these
windings carry m-phase symmetrical current
systems of frequency f
sand f
ron the stator and
rotor respectively. To be able to obtain a d.c.
machine in this configuration, the frequency
changer must be inserted between the direct
current supply and the stator windings (see for
instanee reference
53).
A certain amount of power is fed into the
power electronics, passes trom the power
elec-tranies to the air gap of the electrical machine,
and under the assumption of negligible
power-electronic and stator loss (this is nat essential to
the argument however) this power is split
Uf?
in
the rotor into two components- meehamcal
power delivered to the laad, and a remaining
amount of power that manifests itself as rotor
losses unless fed back to the supply system.
lf constant laad torque be assumed, and the
mechanica! speed of the machine changes, the
mechanica! power will also change. Insome types
of PEREM-systems the power electranies are used
to change the stator frequency, and therefore the
amount of power fed across the air gap in such a
case. This makes it possible (in principle) to
deliver a si mil ar torque at two different mechanica I
speeds without changing the losses in the
machine-electronic system, as the speed of
rotation of the magnatie field in the air gap has
been adjusted. This class of systems camprise all
machines where the stator frequency is changed
by the power-electronics, such as
semiconductor-commutator motors ("Stromrichtermaschinen")
frequency-changers feeding squirrel-cage and
synchronous machines etc.
These primary systems or group-1 systems
con-stitute one section of the bibliography.
The relation between mechanica! speed of the
machine and torque delivered may not only be
changed by changing the supply frequency as
indicated above, but amongst other thing·s by
influencing the induced current in the rotor or
adjusting the mean applied stator voltage. In the
case of either of these methods, however, the
amount of power tor the fundamental frequency
fora specific electromagnetic torque in the airgap
remains constant to a first approximation, so that
the system suffers trom heavy rotor losses at low
speeds. lt follows immediately that induction
motors with electronic rotor control and stator
voltage switching will fall in this class.
The remaining types of machine-electronic
systems all camprise conventional d.c. machines
(with mechanica! commutator) with armature
voltage control or field control by electronic
chopper circuits. Strictly speaking it will probably
be better to consider these systems in a class of
their own. In termsof the agreements made
con-cerning the machine configurations (see second
paragraph of this section, 4.2) the power
elec-tronics is located in series with the machanical
frequency changer in the stator for
armature-voltage control or in the case of a field-chopper
in the rotor circuit. The torque-speed relationship
of the transducer without the machanical
fre-quency changer is a vertical line in the
torqua-speed plane (in this case the line is located at
zero speed), and the tunetion of the power
electronics in this case is to change the maximum
torque. The adaptation of the amount of power
crossing the air-gap is the responsibility of the
machanical frequency changer, not of the power
electronics. When the definition of group 11 or
"secondary" systems is the following: Group 11
systems are those systems in which the power
electranies do nat have the tunetion of changing
the amount of power fed across the air-gap of
the machine, but changing the maximum amount
of torque that may be delivered at a specific
speed, all voltage-controlled, field controlled and
induced current controlled systems fall into this
class.
4.3 Comments concerning the
classification that may be found in this
bibliography
In the first instanee one may expect the
existence of a certain amount of general works
dealing with the subject of PEREM-systems or
machine-electronics systems.
1t
will also be
necessary to include works not directly dealing
with the subject. but treating problems of
im-portance to the subject, or by their method of
attack being of value to the study of
PEREM-systems. All works judged to be of such a nature
were included in section
6.1
of the bibliography.
Power electranies in itself constitute an
important part of the activities of any group
working on machine-electronics, and much work
has been done in this field in the past.
1t was
therefore judged to be necessary to include a
section on power-electranies in the bibliography
in order to obtain a balanced survey. Specialised
questions pertaining to semiconductor power
switches constitute an important part of the
problems in the field of machine-electronics at
present. As these works proved to be numerous
the section on power electronics was split into
two parts. Section 6.2 of the bibliography
there-fore deals with the circuit aspects of
power-electronics, while section 6.4 is devoted entirely
to semiconductor power switches. Works on the
nature of all other types of power switches used
in the past, such as controlled and uncontrolled
mercury-arc tubes, thyratrons, vacuum tubes,
copper oxide and selenium rectifiers, etc. have
not been included in the present bibliography.
1t
was feit that the physical aspects of these
elements are not so actual at present tor
engineering purposes.
As discussed in section 4.2 group I
PEREM-systems are included under section
6.3.1
of the
bibliography. Group 11 systems are included under
section 6.3.2, and due to personal interests of
the author have been divided into two
sub-sections, i.e.
6.3.2
(a): systems with rotor control,
and 6.3.2 {b): systems with voltage controL
The different sections of the bibliography are
therefore:
6.0 List of journals cited in the bibliography.
6.1
General publishad work (concerning power
electronics, rotating electromechanical
transducers and machine-electronics).
6.3 PEREM-systems or machine-electronic
systems.
6.3.1 Group 1-systems (works concerning
the study of inverters in
com-bination with synchronous and
in-duction machines).
6.3.2 Group 2-systems.
(a) Works concerning rotor control
of induction machines.
(b) Works concerning voltage
con-trolled machines.
6.4 Semiconductor power switches.
6.5 Alphabetical list of authors.
5
PRACTICAL COMMENTS
CONCERNING COMPILATION OF
THE BIBLIOGRAPHY
5.1 Selection
As previously stressed the bibliography
re-presents a selected colleetien of works on machine
and power electronics. lt is not possible to obtain
or read every item of publishad literature on the
subject, nor include all these in a bibliography.
In many cases an abstracting journal was
em-ployed to evaluate the contents of a certain
publication. lt is realised that this procedure is not
only dependent on the judgment of the author,
but also on the abstracter, and not always
dependable.
Many of the publishad contributions concern
description of fabricated apparatus, discussion of
oparation or installation problems etc. While this
material is in itself necessary
tor
the engineering
profession, it is not of great significanee to the
present study, and has been omitted as far as
possible. Practical or descriptive work has been
included only when it contained an essential
element
tor
developing a theoretica! background.
5.2 Histograms
To indicate the growth of the different fields,
histograms of the amount of publishad literature
included in the bibliography have been compiled.
Units of five years have been assumed reasonable.
Befare drawing conclusions trom these histograms
(a tempting tendency) one must remamber that
the bibliography represents a selected collection.
On the other hand these histograms are valuable
tor
judging the relativa activity at a certain time.
5.3 Further extensions of the bibliography
Depending on circumstances it is hoped that
in the future the bibliography may be brought
up to date periodically. The author would be
extremely grateful for any correspondence
poin-ting out errors or adding to or correcpoin-ting the
historica! background.
REFERENCES
Görges, H.
Ueber Drehstrommotoren mit verminderter Touren-zahl.
ETZ no. 33, 517-518, 1896.
2 Laithwaite, E. R.,
Electrical varia bie speed drives.
Engineer's Digest, 25 (1 0), 115-165, 1964. 3 Braun, F., Pogg. Ann. 153, 556, 1874. 4 Spenke, E., Elektronische Halbeiter. Springer, 1955. 5 Presser, E., ETZ, 53, 339, 1932. 6 Grondahl,
L.
0., Science, 36, 306, 1926. 7 Rissik, H.,Mercury-arc current converters. Pitman, Londen, 1935. 8 Prince, D. C.,
The direct current transfarmer utilizing thyratron tubes.
G. E. Rev. 31, 347-350, 1928.
9 Kopelmann, F.,
Der Kontaktumformer.
ETZ, 62, 3-16, 1941.
10 Shockley, W., Sparks, M., Teat G. K., p-n Junction transistors.
Phys. Rev.
83
(1 ), 151-162, 1951.11 Ebers, J. J., Moll, J.
L.,
Large signa! behaviour o.f junction transistors.
Proc. I.R.E., 42, (12), 1761-1772, 1954.
12 Moll, J.
L.;
Tannenbaum, M.; Goldey, I.M.; Holonyak,N.
p- n- p- n transistor switches.
Proc. I.R.E., 44, (9), 1174, 1956.
13 Gentry, F. E.; Gutzwiller, F. W.; Holonyak, N.; Zastrow, E. E. von,
Semiconductor controlled rectifiers. Prentice-Hall. New Jersey, 1964.
14 Gentry, F. E.; Scace, R. I.; Flowers, J.
A three terminal a.c. switch.
IEEE Electron Device Conference, Washington, Oct. 31-Nov.1963.
15 Tschudy, W.,
Experimentene Untersuchungen am Quecksilber-dampf-Gieichrichter für Wechselstrom.
Diss. ETH., Zürich, 1914.
16 Prince, D. C., The lnverter.
G.E. Rev. 28, 676-681, 1925. 17 Wagner, C. F.,
Parallel inverter with resistive load.
Al EE Trans., 54, 1227-1235, 1935.
18 Sabbah, C. A.,
Series-parallel type static converters.
G.E. Rev .. 34, 288-301 1931.
19 Petersen: discussion of M. Schenkel:
Technische Grundlagen und Anwendungen ges-teuerter Gleichrichter und Umrichter.
ETZ, 53, 761-770. 1932.
Discussion: 771-773. 20 Ward, E. E.,
lnvertor suitable for operatien over a range of frequency.
Proc. I.E.E., 111, 1423-1433, 1964.
21 Hamudhanov, M. Z.,
"Variable frequency operatien of asynchronous motors using electronic frequency changers" in: Technica! problems of electric drives.
U.S.S.R. Academy of Science. 1957.
22 Zeeuw, W. J. de,
Private communication.
Technological University Eindhoven. 23 Tröger, R.,
Technische Grundlagen und Anwendungen der Stromrichter.
Elekt. Bahnen,
8,
51 -58, 1932.24 Mapham, N. W.,
The classification of SCR inverter circuits.
IEEE Intern at. Conv. Rec., 12 (Pt. 9), 99-105, 1964.
25 Löbl, 0.,
Bahnumrichter System Löbl/RWE.
Elektr. Bahnen, 8, 65-69, 1932.
26 Elektr. Bahnen, 11, 235, 1935.
27 Schenkel, M., lssendorff, I. von,
New arrangement of high power rectifier for power control, inverted eperation and frequency conver-sion.
Siemens Zeitschrift, 11. 142-146, 1931.
28 Schenkel, M.,
Eine unmittelbare asychrone Umrichtung für
niederfrequente Bahnnetze.
Elektr. Bahnen,
8,
69-73, 1932.29 Bolliger. A.,
Die Hochspannungs- Gleichstrommaschine. Springer, Berlin, 1921.
