Testing of Electric Drive with a Serial Connection of the Same Phases of
Two Induction Motors through Computer Simulation
MIKHAIL PUSTOVETOV
Department of Electrical and Electronics Engineering,
Don State Technical University,
344000, Rostov region, Rostov-on-Don, Gagarin sq., 1,
RUSSIA
Abstract: Objective - check the functionality of the circuit of an electric locomotive fan drive that is not speed-
controlled, containing two induction motors, the same stator phases of which are connected in series. Methods:
computer simulation of electric drive at rated voltage and under-voltage at different values of shaft load and not
equal parameters of motors. The simulation results are presented. Results: the simulation showed that, despite
the possibility of sustainable operation at rated voltage, this scheme at under-voltage supply is unstable.
Conclusion: the auxiliary electric drive circuit with a series connection of the phases of two induction motors is
not recommended for use.
Key-Words: - auxiliary electric drive, electric locomotive, induction motor, computer simulation, capacitive
voltage divider, fan, parameters.
Received: January 27, 2023. Revised: Octobert 22, 2023. Accepted: November 24, 2023. Published: December 29, 2023.
1 Introduction
This article describes an example of the
implementation of one of the main objectives of the
computer simulation when it is used in the synthesis
of new schemes of electric drives, namely: to test
the feasibility and quality of operation of the
proposed scheme, taking into account the specific
conditions of use, based on which a decision is
made about the suitability or unsuitability of the
considered option. Specifically examined the
functioning of the electric locomotive auxiliary
drive with a series connection of the same phases of
two 3-phase induction motors.
2 Problem Formulation
To simulate the direct start of two 4-pole squirrel-
cage induction motors (IM) of type NVA-55 or
ANE-225 (used in the auxiliary electric drive of AC
electric locomotives in Russia, [1], [2], [3], [4], [5]),
the same phases of which are connected in series,
author uses the mathematical model of 3-phase IM
which described in, [2], (rotor parameters of IM
reduced to stator, [6], [7], [8]). Modeling of the fan
load (bottom in Figure 1) was performed according
to, [2]. The stator windings of two motors represent
a three-phase symmetrical system, connected in a
wye circuit without a neutral wire. To equalize the
voltage distribution of two motors between the
beginning and the end of each stator phase winding,
a capacitor is connected in parallel to the winding
(C-voltage divider, Figure 1). The ratings of all
capacitors are the same (1000 μF each in Figure 1).
OrCAD is used as a tool for simulation, [9], [10],
[11].
3 Problem Solution
It was revealed that at a load corresponding to the
rated power of the IM, the system does not provide
stable operation even in the ideal case, when the
parameters in each of the motors and each of the
loads are the same (Figure 2). In this case, the
presence or absence of capacitive dividers, as well
as the ratings of the capacitors, is not of
fundamental importance.
The process develops as follows. Differences in
IMs’ load are gradually increasing. One of the IMs
“stalls”: the electromagnetic torque drops (gradually
to zero) and, as a consequence, the rotation speed
too. Another IM accelerates above the rated rotation
speed, without reaching the synchronous speed, i.e.,
from the moment the speed of the first IM drops, the
speed of the second increases. The second IM
operates stably at an increased rotation speed. On
the IM that loses torque, the voltage decreases. On
the stator of the IM remaining in operation, the
voltage increases. The phase currents of the
corresponding IMs behave similarly.
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DOI: 10.37394/23201.2023.22.17
Mikhail Pustovetov
E-ISSN: 2224-266X
152
Volume 22, 2023
Fig. 1: View of the OrCAD-based, [9], [10], [11] computer model of an electric drive of two motor-fans
with a series connection of the phases of stators of the IM of type NVA-55 . Between the beginning and end of
each phase winding of the stator, a capacitor is connected parallel to the winding
With unequal parameters, the IM tends to “stall”:
with a larger moment of inertia, a larger load torque
on the shaft, less inductance, and a larger resistance.
Stable operation of two series-connected IM
motor fans can be achieved if three conditions are
met:
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1) in capacitive voltage dividers, resistances
must be connected in series with the
capacitors (RC voltage divider, Figure 3);
Fig. 2: Instability of joint operation of a pair of series connected IMs with completely identical parameters.
Results of simulation of rotation speeds (graphs 1 and 2) and load torques (graphs 3 and 4) of two NVA-55
IMs. Graphs 1 and 3 refer to one IM, 2 and 4 to another IM
2) the loads on the motors’ shafts at the rated
supply voltage should be significantly lower
than the rated one (for stable operation of
two series connected motors at similar
conditions, the load of each should not
exceed 50% of the rated one);
3) the loads on the motors’ shafts must be the
same.
You can calculate the load torque on the shaft of
one IM of type NVA-55 during long-term operation
in traction mode of an electric locomotive using data
from, [12], which says: “On the EP1 mainline
passenger AC electric locomotive, the power
consumed by the fans and oil-pump at rated mode
and operation in traction is equal to 110 kW". This
refers to four motor fans with NVA-55 and one oil
pump. Assuming the power of the IM driving oil
pump is significantly less than that of the NVA-55,
we will approximately calculate the shaft power of
one NVA-55: 110/4 = 27.5 kW. The torque on the
shaft will be 27500/(1440∙6.28/60) ≈ 180 N∙m. This
is 49.8% of the rated value (364 N∙m). It is known,
[2], [13], that in the long-term operation of the
VL85 mainline freight AC electric locomotive, the
power of the IM of type ANE-225 with a TsVV 89-
15 centrifugal fan on the shaft is 32.5 kW, the
torque is 32500/(1440∙6.28/60) ≈ 216 N∙.m. This is
59.3% of the rated torque value for NVA-55.
According to data, [1], [13], the IM of auxiliary
drives of an electric locomotive must be capable of
operating without voltage stabilization in the range
of catenary voltage variations ±25% of the rated
one.
Assuming that one NVA-55 has standard
parameters (the moment of inertia reduced to the
motor shaft, J = 5 kg∙m2, is taken for each motor),
and the other has a 10% lower main inductance, and
also that the fan is used as a load on the shaft
provides 10% less load than that of the first IM (on
the shaft of the IM with standard parameters at a
rotation speed of 150.906 rad/s the load torque is
180 N∙m, and for the second IM is 162 N∙m only),
we will simulate the turn-on of the circuit at the
supply voltage, at 25% less than rated. The results
(with the value of each capacitance of 1000 μF) are
shown in Figure 4: the rotation speed of the IM with
standard parameters at the end of the transition
process is set at a normal level, slightly lower than
1500 rpm, and the rotation speed of the IM with a
less main inductance is significantly lower. The
phase voltage value for IM with standard parameters
is higher than normal. The phase voltage at stator
terminals of “non-standard” IM is significantly
lower than normal.
Computer simulation for the case of loading with
a fan of type TsVV 89-15 at reduced voltage gave
similar results. The stable operation of a pair of IMs
is noted, but with very different characteristics. The
currents of the same phases in two IMs are the
same.
At the rated supply voltage, in the case of the
same load of two IMs with TsVV 89-15 fans, the
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DOI: 10.37394/23201.2023.22.17
Mikhail Pustovetov
E-ISSN: 2224-266X
154
graphs of changes in voltages and rotation speeds of
the IM are similar to those shown in Figure 4.
Fig. 3: OrCAD hierarchical block symbolizing the computer model of the IM of type NVA-55. In capacitive
dividers, 100 Ohm resistances are connected in series with 1000 μF capacitors
Fig. 4: Results of computer simulation the operation of two series-connected IMs at a supply voltage 25% less
than the rated (graphs of phase voltages and IM rotation speeds). 1 – rotation speed of the IM with standard
parameters; 2 – rotation speed of the IM with a less main inductance; 3 – graph of the voltage of the IM with a
less main inductance. The graph 4 of the IM voltage with standard parameters is shifted down 1000 V for
greater clarity
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DOI: 10.37394/23201.2023.22.17
Mikhail Pustovetov
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155
Fig. 5: Results of computer simulation the operation of two NVA-55 with different parameters at the rated
supply voltage with the same fan loads on the shafts (graphs of phase voltages and motor rotation speeds). All
designations similar to Figure 4
Simulation of the operation of two NVA-55 with
different (see above) parameters at rated voltage
with the same fan loads on the shafts of 180 N∙m
(torque value at a rotation speed of 150.906 rad/s)
gave significantly better results (Figure 5). Both IMs
operate stably in similar modes, both in terms of
rotation speed and phase voltage.
Graphs similar to those presented in Figure 5 are
obtained in the complete absence of RC dividers on
two series-connected IMs, all other things being
equal. Stable operation of a pair of IMs is not
ensured when installing only C-dividers.
Stable operation in similar modes with an IM
load of 50% is ensured by placing RC dividers in
two phases out of three of each IM (in the same
phases of the IMs). The result is similar to that
shown in Figure 5.
4 Conclusion
Thus, the auxiliary electric drive circuit with a series
connection of the phases of two IMs is not
recommended for use, since it does not provide
sufficient stability of the motor when the supply
voltage decreases, despite the possibility of
sustainable operation at rated voltage. Besides this
for stable operation, it demands significantly less
(50 %) loads on the shafts than rated.
References:
[1] Gulyaev A.V., Ten E.E., Fokin D.S.,
Shukharev S.A., Simulating the operation of
auxiliary machines of a 2(3)ES5K locomotive,
Russian Electrical Engineering, Vol.87, 2016,
pp. 93–96.
https://doi.org/10.3103/S1068371216020073.
[2] Pustovetov M., Shukhmin K., Goolak S.,
Matijošius J., Kravchenko K., Induction
Motor Computer Models in Three-Phase
Stator Reference Frames: A Technical
Handbook, Bentham Science Publishers Pte.
Ltd. Singapore, 2023. https://doi.org/
10.2174/97898151243091230101.
[3] Piskunov S.V., Efremov A.P., Electric motors
for drives of modern locomotive auxiliaries.
Russian Electrical Engineering, Vol.79, 2008,
pp. 642–643.
https://doi.org/10.3103/S1068371208110126.
[4] Girnik A.S., Fedyanin A.L., "Simulation of
auxiliary induction motors with asymmetric
power and circuit rotor in using on the
locomotives," 2012 7th International Forum
on Strategic Technology (IFOST), Tomsk,
Russia, 2012, pp. 1-5, https://doi.org/
10.1109/IFOST.2012.6357674.
[5] Girnik A.S., Dixon R.C., "Control of
overheating condition for induction motors,"
2012 7th International Forum on Strategic
Technology (IFOST), Tomsk, Russia, 2012,
pp. 1-5,
https://doi.org/10.1109/IFOST.2012.6357700.
[6] Wildi T., Electrical Machines, Drives and
Power Systems, 6th edition, Upper Saddle
River: Pearson Prentice Hall, 2005.
[7] Boldea I., Nasar S.A., The Induction Machine
Handbook, CRC Press, 2010.
[8] Trzynadlowski A., Control of Induction
Motors, Academic Press, 2001.
WSEAS TRANSACTIONS on CIRCUITS and SYSTEMS
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Mikhail Pustovetov
E-ISSN: 2224-266X
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[9] Keown J, OrCAD PSpice and Circuit
Analysis, 4th edition, Prentice Hall, 2000.
[10] Rashid M.H., SPICE for Power Electronics
and Electric Power, 3rd edition, Boca Raton,
USA: CRC Press, 2012.
[11] Fitzpatrick D., Analog Design and Simulation
Using OrCAD Capture and PSpice, 2nd
edition, Newnes, 2017.
[12] A. M. Rutshtein, Adjustable auxiliary electric
drive of electric locomotive EP1, Electrical
Locomotives Building (Elektrovozostroenie),
Vol.40, 1998, pp. 213–221.
[13] Shukhmin K.A., Yanov V.P., Dependence of
the characteristics of the auxiliary motor of
type ANE-225 of electric locomotive on the
parameters of the squirrel cage, Electrical
Locomotives Building (Elektrovozostroenie),
Vol.39, 1998, pp. 178–182.
Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting
Policy)
The author equally contributed to the present
research, at all stages from the formulation of the
problem to the final findings and solution.
Sources of Funding for Research Presented in a
Scientific Article or Scientific Article Itself
No funding was received for conducting this study.
Conflict of Interest
The author has no conflicts of interest to declare.
Creative Commons Attribution License 4.0
(Attribution 4.0 International, CC BY 4.0)
This article is published under the terms of the
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WSEAS TRANSACTIONS on CIRCUITS and SYSTEMS
DOI: 10.37394/23201.2023.22.17
Mikhail Pustovetov
E-ISSN: 2224-266X
157