Modeling and Real-Time Simulation of Induction Motor Using RT-LAB

International Journal of Power Electronics and Drive System (IJPEDS)
Vol. 9, No. 4, December 2018, pp. 1476~1485
ISSN: 2088-8694, DOI: 10.11591/ijpeds.v9.i4.pp1476-1485  1476
Journal homepage: http://iaescore.com/journals/index.php/IJPEDS
Modeling and Real-Time Simulation of Induction Motor
Using RT-LAB
A. Hamed, A. Hazzab
Department of Electrical Engineering, Laboratory (COASEE), Tahri Mohamed Bechar University, Algeria
Article Info ABSTRACT
Article history:
Received Mar 18, 2018
Revised Aug 12, 2018
Accepted Sep 8, 2018
This paper presents the modeling and real-time simulation of an induction
motor. The RT- LAB simulation software enables the parallel simulation of
power drives and electric circuits on clusters of a PC running QNX or RT-
Linux operating systems at sample time below 10 µs. Using standard
Simulink models including SimPowerSystems models, RT-LAB build
computation and communication tasks are necessary to make parallel
simulation of electrical systems. The code generated by the Real-Time
Workshop of RT- LAB is linked to the OP5600 digital real-time simulator. A
case study example of real-time simulation of an induction motor system is
presented.This paper discusses methods to overcome the challenges of real-
time simulation of an induction motor system synchronizing with a real-time
clock.
Keyword:
RT-LAB
Real-Time
Induction motor
Modeling
Simulation Copyright © 2018 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
A. Hamed,
Department of Electrical Engineering,
Laboratory (COASEE), Tahri Mohamed Bechar University Algeria ,
Bechar University, Street Of Independence, BP 417, Bechar, Algeria.
Email: hamedali1985@yahoo.fr
1. INTRODUCTION
The induction motor is used in many industrial sectors as the main element of converting electrical
energy into a mechanical drive because of its low cost, robustness, high degree of reliability and good power-
to-weight ratio. Due to its feature sand high applicability in industrial fields, studies for higher efficiency
have always been demanded.
As testing and validation of induction motor has become more and more important in the design and
engineering process, the need for constant improvement of component modeling and for increasing the speed
of prototyping the system has also become greater. Conventionally, validation of a induction motor was done
by non-real-time simulation of the concept at early stage in the design, and by testing the system once the
design is implemented. But this method has some major drawbacks:first, the leap in the design process, from
off-line simulation to real prototype is so wide that it is prone to many troubles and problems related to the
integration at once of different modules; second, the off-line, non-real-time, simulation may become
tediously long for any moderately complex system, especially for motor drives with switching power
electronics [1].
Real-time simulation of induction motor is a valuable tool for development and testing of
control.Two situations can arise depending on the time required by the simulation platform to complete the
computation of state outputs for each time-step (Figure 1): 1) if the execution time, Te, for the simulation of
the system is shorter or equal to the selected time-step, the simulation is considered to be real-time (Figure 1
(a)); and 2) if Te is greater than its time-step size for one or more time-steps, overruns occur and the
simulation is considered as non-real-time or offline. In the latter case, either the time-step can be increased or
the system model can be simplified to run it in Real-Time [2]-[5].

Int J Pow Elec & Dri Syst ISSN: 2088-8694 
Modeling and Real-Time Simulation of Induction Motor Using RT-LAB (A. Hamed)
1477
Figure 1. Illustration of real-time and offline simulation: (a) Real-time simulation.
(b) Non-real-time simulation
This paper presents the modeling and real-time simulation of an induction motor in a power system.
Matlab/Simulink software is used to develop the induction motor model. The generated code of the Simulink
model is linked to the OP5600 digital real-time simulator in order to simulate the induction motor.
The paper is divided into six sections, the hardware and software configuration of RT-LAB is
presented in section 2, section 3 shows the mathematical model of the induction motor, a detailed modeling
of an induction motor in RT-LAB is shown in secion 4. Section 5 illustrates the real time simulation results
using RT-LAB, finally the conclusion is drawn in section 6.
2. RT-LAB CONFIGURATION
RT-LAB is an industrial-grade software package for engineers who use mathematical block
diagrams for simulation, control and related applications. The software use popular programming tools such
as MATLAB/Simulink and works with viewers such as Lab VIEW and programming languages including
C++. RT-LAB allows the user to readily convert Simulink Models to real-time simulations, via Real-Time
workshop (RTW) and run them over one or more PC processors [1],[4]-[6].
2.1. Hardware Configuration
RT-LAB software runs on a hardware configuration consisting of command station (host node),
target nodes, the communication links (real-time and Ethernet), and the I/O boards [7].
2.1.1. The Command Station
The command station is a PC workstation that operates under Windows, and serves as the user
interface. The command station allows users to: edit and modify models; see model data; run the original
model under its simulation software (Simulink, SystemBuild, etc.); generate and separate code; and control
the simulator's Go/Stop sequences [7].
2.1.2. Target nodes
The target nodes are real-time processing and communication computers that use commercial
processors interconnected by an Ethernet adapter. The real-time target nodes perform:
a. Real-time execution of the model’s simulation;
b. Real-time communication between the nodes and I/Os;
c. Acquisition of the model’s internal variables and external outputs through I/O modules [8],[9];

 ISSN: 2088-8694
Int J Pow Elec & Dri Syst, Vol. 9, No. 4, December 2018 : 1476 – 1485
1478
Figure 2. Communication between the Console and Target Node
The command node and target node are commercial PC’s with different operating system. A PCI-
626 I/O card (from Sensory Company Inc.) is used which satisfies all I/O requirements. Moreover, it is
supported by RT- Linux real-time operating system. In this configuration the only communication link used
is between the target and command station using Ethernet communication [7].
2.2. Software Configuration
For the above configuration of RT-Lab, the software in the command station (console) is Windows,
and the simulation software is Matlab-Simulink to program the simulation and control tasks. The simulation
program is coded into C code in the consol unit and transferred to the target node, which has linux operating
system. The target unit compiles and executes the C code file in parallel with the simulation program in the
console. The data is transferred on-line between the target and console throw communication Ethernet. In the
consol station, the program is written in two main blocks (Consol-Master).
SM_: master subsystem. There is always one and only one master subsystem inside a model.it
contains the computational elements of the model.
SC_: console subsystem. The console subsystem is the subsystem operating on the command station
that enables you to interact with the system .it contains all the simulink/systembuild blocks related to
acquiring and viewing data (scope, manual switch, to workspace-type blocks, etc).the blocks you need,
whether it is during or after the execution of the real-time model, must be included in the console
subsystem.the console runs asynchronously from the other subsystems.note that there can only be one
console per model [10]-[12].
2.3. Opcomm Communication Blocks
Once the model is grouped into console and computation subsystems, special blocks called opcomm
blocks must be inserted into the subsystems.these are simple feed-through blocks that intercept all incoming
signals before sending them to computation blocks within a given subsystem.opcomm blocks serve several
purposes.
When a simulation model runs in the RT-LAB environment,all connections between the main
subsystems(SC_,SM_,or SS_)are replaced by hardware communication links .for communication between
real-time target nodes(SM_ and SS_)RT-LAB uses adesignated real-time link.for communication between
the console(SC_)and the real-time nodes(SM_ or SS_)RT-LAB uses TCP/IP.
Because of these communication links between nodes, the simulation may not run the same way in
simulink or systemBuild as in RT-LAB. In RT-LAB, a computation subsystem waits for reception of all
signals before it is able to start calculating.in Simulink and SystemBuild,on the other hand,computations
performed on a signal start as soom as the signal is available,OpComm blocks emulate the behavior of the
system as it is run in RT-LAB [10].
2.4. Recording Data with OpWriteFile
To obtain all data for any particular signal, use the OpWriteFile block data recorded with this block
is stored on the target real-time node’s hard drive.the data file is automatically transferred to the command
station when the model is reset [10].
2.5. EXtreme High Performance (XHP) Mode
The XHP mode is a means for the real-time operating system to disable interrupts.this is done on a
per-subsystem (thus per-CPU) basic.not allowing interrupts prevents process switching which removes
latencies time for additional computation in the same time slice. The XHP mode is aimed at real-time
applications of a given base sample time that cause overruns (overflow their allowed time-step for

1479
computation) while running in RT-LAB in the standard mode. In XHP mode, the model waits in an empty
loop for its next scheduled step.the next model step is then computed.
In this mode, we use the CPU counter as our time reference.because this counter operates at the
CPU’s frequency, it offers a very high resolution, even for step-size in the microsecond range.because the
counter resides on the CPU and reading its value is done within one CPU cycle, this operation introduces
almost no latency [10].
3. INDUCTION MOTOR MODELING
The mathematical models of induction motor in the park frame are written as follows [13]-[19].
Vsd = Rs. Isd +
dϕsd
dt
− Wa. ϕsq
Vsq = Rs. Isq +
dϕsq
dt
− Wa. ϕsd
Vsd = Rr. Ird +
dϕrd
dt
− Wr. ϕrq
Vrq = Rr. Irq +
dϕrq
dt
− Wr. ϕrd (1)
The stator and rotor fluxes are related to the current by:
ϕsd = Ls. Isd + Lm. Ird
ϕsq = Ls. Isq + Lm. Irq
ϕrd = Ls. Ird + Lm. Isd
ϕrq = Ls. Irq + Lm. Isq (2)
The stator and rotor angular velocities are linked by the following relation:
Ws = W + Wr (3)
The equations of mechanical and electromagnetic torques are:
J
dΩ
dt
= Te − Tm − fΩ (4)
Te = P(ϕrqIrd − ϕrdIrq), Ω =
W
P
(5)
where: Rs is stator resistance, Rr is rotor resistance, Ls and Lr are respectively stator and rotor inductance Lm
the mutual inductance, ϕsd and ϕsq are the direct and quadrature stator flux, ϕrd and ϕrq are the direct and
quadrature rotor flux, Isd and Isq are the direct and quadrature stator current, Ird and Irq are the direct and
quadrature rotor current, P is the number of pair poles, Ws and Wr are the asynchronous and rotor angular
frequency, Te and Tm are the electromagnetique and mechanical torque, and F is the viscosity coefficient.
To get a model state in terms of the rotor sizes ( Ird , Irq , ϕrd , ϕrq),We express the stator sizes
( Isd , Isq , ϕsd , ϕsq) in terms of rotor sizes [13].
Isd =
ϕrd
Lm
−
Lr
Lm
Ird
Isq =
ϕrq
Lm
−
Lr
Lm
Irq
ϕsd =
Ls
Lm
ϕrd + δ Lm Ird
ϕsq =
Ls
Lm
ϕrq + δ Lm Irq (6)
By using equations (1) and the equations (6) of the IM, we obtain the dynamic model of induction
motor having as state vector (Ird , Irq, ϕrd , ϕrq , w):
dIrd
dt
=
(Rs Lr+ Rr Ls)
Lm
Ird + wa Irq −
Rs
δ Lm
2 ϕrq +
Ls
δ Lm
2 wϕrq +
Vsd
δ Lm
−
Ls
δ Lm
2 Vrd

 ISSN: 2088-8694
1480
dIrq
dt
=
(Rs Lr+ Rr Ls)
δ Lm
2 Irq + wa Ird −
Rs
δ Lm
2 ϕrq +
Ls
δ Lm
2 w ϕrd +
Vsd
δ Lm
−
Ls
δ Lm
2 Vrd
dϕrd
dt
= −Rr. Ird + waϕrq − wϕrq + Vrd
dϕrq
dt
= −Rr. Irq + waϕrd − wϕrd + Vrq
dw
dt
=
P2
J
(ϕrqIrd − ϕrdIrq) +
P
J
(Tm − fw) (7)
4. MODELING INDUCTION MOTOR IN RT-LAB
In RT-LAB all top-level subsystems must be named with a prefix identifying their function .The
prefixes are: SC_ for consol sybsystem and SM_ for master subsystem.
Depending on the type of data acquisition, we propose two RT-LAB models; in the first model the
data transfer between the target node and the console machine is during the simulation task, however in the
second one, the transfer will be done after the end of simulation performed.
4.1. Data Acquisition during Simulation
In this case RT-LAB enables signal acquisition from a real-time target during simulation using
OpComm block for synchronization between target node and console.
Figure 3. RT-Lab Real-Time simulation graphic model of IM
Figure 4. Master subsystem of induction mtor with opcomm block

1481
Figure 5. Console subsystem of induction motor with opcomm block
We use OpComm block in master and console subsystems; the consol sends the signal of Resistant
Torque to the master subsystem and the latter sends signals of Isa,Isb,Isc,Ids,Iqs,Qrd,Qsd,Ce,Speed to the
console subsystem.
4.2. Data Acquisition after the End of Simulation
In this case, we use OpWriteFile block for recording all data in the target node’s hard disk, and
when the simulation ends, the target node sends recorded data in matefile format to the console.
Figure 6. RT-Lab Real-Time simulation graphic model of IM with OpWriteFile Block

 ISSN: 2088-8694
1482
Figure 7. Master subsystem of induction motor with OpWriteFile Block
We use an OpWriteFile block in master subsystem for recording simulation data
Figure 8. Console subsystem of induction motor without opcomm block
The OpComm block is not used in the console subsystem.
5. RESULTS AND ANALYSIS
All the simulations are carried out on an induction motor whose parameters are listed in the Table 1.
Table 1. Induction motor parameters
Parameters Symbols Input values
Rotor Resistance
Stator Resistance
Rtor Inductance
Stator Inductance
Inductance mutual
Phase voltage
frequency
pair of pole
Rr
Rs
Lr
Ls
Lm
Vph
f
p
3.81
4.85
0.274
0.274
0.258
220
50
2
We applied a resistant torque to the induction motor at time 2.0 s to 3.0 s. Figure 9 shows the speed
response in real-time simulation in different times steps.Through the red curve we note that there is no data

1483
loss when we use 30 µs as time-step, The response is the same as in offline simulation.In the second case,
when we use 20 µs as time-step it is shown clearly in the zoom graph that it started to loss data, However in
the last case when we use 10 µs as time-step we observe that data was considerably lost and the signal of the
speed has completely changed.
Figure 9. Speed respone of induction motor in different time-steps
We conclude that the acquisition data from the target node during simulation leads to the data loss if
the time-step is small then 20 µs, because TCP/IP is relatively slow compared with most real-time systems
like fireWire-type network.
Figure 10 shows the speed response in second proposal where OpWriteFile block is used. In this
case the target node does not send data to the console while the simulation is running. After simulation ends,
the target node sends the recorded data in hard disque of target as mat file content all signal information to
the console.
Figure 10.speed respone of induction motor in real-time with opwritefile block
We note from the curve that although very small time-step is used compared to the previous
experiment, no data loss occurred just as in offline simulation. Later, a simulation attempt with time-step as
0,1 µs caused overruns and the simulator showed the following error message

 ISSN: 2088-8694
1484
Figure 11. Overruns detected
6. CONCLUSION
In this paper we proposed two RT-LAB models for real-time simulation of the induction motor, in
the first, model, data acquisition was during simulation, however in the second model, data acquisition was
after the end of simulation, The simulation results show that in the first model we got data loss when we use
small time-step because TCP/IP is relatively slow compared with real-time systems like fireWire-type
network. However in the second model no data loss occured.
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BIOGRAPHIES OF AUTHORS
Hamed Ali was born on 18th december 1985 in bechar, Algeria he received the ingeniorat degree
in computer science from the Bechar University, Algeria in 2008 and the master degree in
computer science from the Tahri Mohammed Bechar University, Algeria in 2012. In 2014, he
was a laboratory membre at, Laboratory of Control Analysis and Optimization of the Electro-
Energetic Systems (CAOSEE). His research interrest covers, power electronics electric drives
control, real-time simulation and artificial intelligence.
e-email : hamedali1985@yahoo.fr
Hazzab Abdeldjebar received the state engineer degree in electrical engineering in 1995 from the
University of Sciences and Technology of Oran (USTO), Algeria the M.Sc. degree from the
Electrical Engineering Institute of the USTO in 1999, and the Ph.D. degree from the Electrical
Engineering Institute2 of the USTO in 2006. He is currently professor of electrical engineering
at University of Bechar, Bechar, Algeria, where he is Director of the Research Laboratory of
Control Analysis and Optimization of the Electro-Energetic Systems. His research interests
include power electronics, electric drives control, and artificial intelligence and their
applications.

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