– A Modular Approach
Leon M. Tolbert1,2
Oak Ridge National Laboratory
P.O. Box 2009
Oak Ridge, TN 37831-6472
Department of Electrical and Computer
The University of Tennessee
Knoxville, TN 37996-2100
parameters are accessible for control and verification
Simulink induction machine model discussed in this paper
has been featured in a recent graduate level text book , and it also has been used by different scholars in the US [7-9], Korea, and Brazil [10-12] in their research.
Abstract - In this paper, a modular Simulink implementation
of an induction machine model is described in a step-by-step approach. With the modular system, each block solves one of the model equations; therefore, unlike black box models, all of the machine parameters are accessible for control and verification purposes.
After the implementation, examples are given with the model
used in different drive applications, such as open-loop constant V/Hz control and indirect vector control are given. Finally, the use of the model as an induction generator is demonstrated.
II. INDUCTION MOTOR MODEL
The induction machine d-q or dynamic equivalent circuit is
shown in Fig. 1. One of the most popular induction motor
models derived from this equivalent circuit is Krause’s model detailed in . According to his model, the modeling
equations in flux linkage form are as follows:
Usually, when an electrical machine is simulated in circuit
simulators like PSpice, its steady state model is used, but for electrical drive studies, the transient behavior is also
important. One advantage of Simulink over circuit simulators is the ease in modeling the transients of electrical machines and drives and to include drive controls in the simulation.
As long as the equations are known, any drive or control
algorithm can be modeled in Simulink. However, the
equations by themselves are not always enough; some
experience with differential equation solving is required.
Simulink induction machine models are available in the
literature [1-3], but they appear to be black-boxes with no
internal details. Some of them [1-3] recommend using Sfunctions, which are software source codes for Simulink blocks. This technique does not fully utilize the power and
ease of Simulink because S-function programming
knowledge is required to access the model variables. Sfunctions run faster than discrete Simulink blocks, but Simulink models can be made to run faster using
“accelerator” functions or producing stand-alone Simulink models. Both of these require additional expense and can be
avoided if the simulation speed is not that critical. Another approach is using the Simulink Power System Blockset 
that can be purchased with Simulink. This blockset also
makes use of S-functions and is not as easy to work with as
the rest of the Simulink blocks.
Reference  refers to an implementation approach similar
to the one in this paper but fails to give any details.
In this paper, a modular, easy to understand Simulink
induction motor model is described. With the modular
system, each block solves one of the model equations;
therefore, unlike black box models, all of the machine
= ωb vqs −
Fds + s (Fmq + Fqs )
= ω b vds + e Fqs + s (Fmd + Fds )
(ω e − ω r )
(ω − ω r )
= ω b v dr + e
Fqr + r (Fmd − Fdr )
Fmq − Fqr
= ω b v qr −
Fig. 1. Dynamic or d-q...