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M.Pradeep Kumar et al. Int. Journal of Engineering Research and Application www.ijera.com
Vol. 3, Issue 5, Sep-Oct 2013, pp.282-287
www.ijera.com 282 | P a g e
Design of Pmsm Based On Dtc Method with Mras
M. Pradeep Kumar*, S. Sirisha**, M. Chandramouly***
*(PG Scholar, Department of EEE, TKR College of Engineering &Technology, Hyderabad.)
** ( Department of EEE, TKR College of Engineering &Technology, Hyderabad.)
*** (Centre for Energy Studies JNTU college of Engineering Hyderabad.)
ABSTRACT :
Permanent magnet synchronous motors (PMSM) are appropriate for applications with load-independent
speeds or synchronous operation with high accuracy under defined speed. In this paper analysis the structure and
equations of the PMSM, direct torque control (DTC) and voltage space vector process then study model
reference adaptive system (MRAS) estimators. The PI controller uses from estimate speed feedback and do the
speed sensor less control of PMSM based on DTC method with MRAS. The simulation results show that the
speed of rotor estimates with high precision and torque response is considerably fast.
Keywords - permanent magnet synchronous motor; speed control; direct torque control; model reference adaptive
system.
I. INTRODUCTION
In the last years permanent magnet synchronous
motor, because of properties such as high efficiency,
high torque, high power, small volume and accurate
speed control have become more attention and uses in
chemical industry, texturing plants, glass industry,
transport systems, electrical household appliances,
ship engines, robotic automation, and escalators. The
control methods used for the permanent magnet
synchronous motors are: V/f control, field oriented
control and direct torque control [1].
The basic principle of DTC is to directly
select stator voltage vectors according to the
differences between the reference and actual torque
and stator flux linkage. The DTC possesses
advantages such as lesser parameter dependence and
fast torque response when compared with the torque
control via PWM current control [2].
Position sensor with higher quality is a
necessary component part of the drive system
employed in So that it is highly desired to develop the
position sensor less technology of PMSM. For the
mechanical position sensor could be bulky and easy to
failure in harsh environments, sensor less technology
can increase the reliability of the drive system.
Research on sensor less technology has increased in
academic and industrial communities over.
During recent years, sensor less drives of
PMSM has attracted much attention. Many techniques
have been proposed in order to estimate the rotor
speed and position, such as open-loop estimators using
stator voltages and currents, back EMF-based position
estimators, MRAS estimators, observe-based position
speed and position estimators, high-frequency signal
injection and artificial intelligence.
This paper adopts the MRAS scheme which uses the
PMSM itself as the reference model to estimate the
speed of the motor [3].
II. PERMANENT MAGNET
SYNCHRONOUS MOTOR TECHNOLOGY
Permanent magnet synchronous motors can be
designed in different structures according to their
application. In this motor permanent magnet can
replacing the DC induction coils of the rotor, that is
supplied the magnetic flux on the rotor. Stator coils
placed on the stator are three phase and the amount of
current drawn from the supply is minimal that leads to
low losses of the rotor and excitation, increase of
efficiency comparable with other motors and savings
on energy costs. The magnets on the rotor have two
following structure:
A. Placing the magnets on the rotor surface
Magnets are installed on the rotor in forms of
strips or arcs. These motors have large air gap and
faint armature reaction and are utilized in low-speed
applications because the low endurance of the magnets
to the centrifugal forces. These motors are usually
known as surface permanent magnet motors
(SPMSM). This motor is shown in Fig. 1.
RESEARCH ARTICLE OPEN ACCESS

Figure1. Magnets on the rotor surface
The differences between Radially and Circular
structure are shown in table 1 [4].
TABLE I. DIFFERENCES RADIALLY AND
CIRCULARSTRUCTURE
II. DIRECT TORQUE CONTROL
DTC is a sensor less technique which
operates the motor without requiring a shaft mounted
mechanical sensor. It is suitable for control of the
torque and flux without changing the motor
parameters and load. In this method torque and stator
flux are directly controlled by two hysteresis
controllers [5-7]. The block diagram of direct torque
control for permanent magnet synchronous motor is
shown in Fig.
Figure4. Block diagram of DTC for PMSM
A. Permanent magnet synchronous motor
Equations
Stator current vector on rotor flux (dq)
reference system as id,iq and the electromagnetic
torque is related with these vectors. Equations (1-3)
and equation (4) are electrical and mechanical model
equations respectively[8].
Where
f = rotor magnetic flux,
Ld = d - axis ststor inductance,
Lq = q - axis ststor inductance,
Rs = stator resistance,
Te = electromagnetic torque,
TL = load torque,
m = mechanical speed,
r = angular speed,
J = moment of inertia,
 = friction coefficient,
P = nuber of pole couples.
Structure of voltage source inverter(VSI) is shown in
fig. 5 at the same time only one switch on the each
column can can be on [5].
By the different selects of the six switches, there are
eight vectors that are six non-zero voltage vectors (V1,
V2, V3, V4, V5, V6) and two zero voltage vectors (V7,
V8) [2]. Lines to line voltages are:
Line-to-neutral voltages are:
The ststor voltages-vectors(V1-V8) can be
expressed in terms of the dc-link voltages (E) which
obtained from transformation motor terminal voltage

to stator D and Q axes. These voltages are show in
table 2 [5].
Stator magnetic flux can be calculated with following
equation:
Value of R is low, equation (12) implies that the flux
vector equal voltages integrate and the stator flux
vector will move in the same direction voltage vector
as shown in Fig. 6.
Figure 6. voltage space vectors
Voltage vectors controlling the amplitude of
the stator flux, so the voltage vector plane is divided
into six regions as shown in Fig. 6. In each region,
there are two adjacent voltage vectors that increase or
decrease the amplitude of s . For example, when s
in region 1, vectors of V1, V2, V6 and V3, V4, V5 are
increase and increse and decrease the amplitude of s
respectively. In this way s can be controlled at the
required value by selecting the proper voltage vectors
[9-12].
Switching table, for controlling both the flux and
torque are indicated in table 3. If = 1, =0 then the
actual flux is smaller and bigger than the refernce
value, respectively. The same is true for the torque.
TABLE III. SWITCHINHG TABLE OF PMSM
III. MODEL REFERENCE ADAPTIVE
SYSTEM
When the motor is running, its parameter will change
and its performance will become bad. Adaptive control
can remove this problem. The model reference
adaptive system (MRAS) is an important adaptive
controller [13]. The rotor speed is included in the (1)
and (2) equations that present current model are
relevant to rotor speed. So the stator current model is
chosen as the state variable:
So equation (14) can be converted to the
equation State of the adjustable model of PMSM with
speed angle as the adjustable parameter as follow:

So with replace equation (17) into equation (16), the
speed adaptive mechanism finally appears [14]:
But the above equation for SPMSM can be simplified
as follow (because Ld = Lq = Ls):
By these equations, block diagram control of the
PMSM based on MRAS can be gotten, and it is shown
as Fig. 7.
Figure7. The block diagram control of based on
MRAS
IV. SIMULATION PMSM BASED ON
DTC METHOD WITH MRAS
ADAPTIVE SYSTEM
With combine Fig. 4 and Fig. 7, can be
estimated the rotor speed and simulate with
MATLAB software Fig. 8 shows the block diagram of
speed sensor less control of PMSM based on DTC
method with MRAS. In Fig. 8, the estimate output
speed of MRAS compare with the reference speed of
input and uses from this speed as real speed of
machine.
Reference speed is 25 rad/s at 0s and then leaps to 10
rad/s at 1s. in the Fig. 9 speed of the motor is 25 rad/s
at 0.8s and 10 rad/s at 1.6s Fig. 10 sows the torque of
the motor. Load torqueis 10N.m as shown in fig. 10,
torque response is fast. Fig. 11 and fig. 12 sow flux of
alfa axis and beta axis.
Figure8. Simulation model of DTC method with
MRAS
OBSERVED WAVEFORMS:
Figure9. Real speed and Estimated speed of PMSM
Figure10. Torque of PMSM
Figure11. Flux of alfa axis

Figure12. Flux of beta axis
Figure13. The current of phase a (ia)
Figure14. The current of phase b (ib)
Figure15. The current of phase c (ic)
Figure16. Magnitude of stator flux
In Fig. 16 flux is constant and about 0.532 wb. Table 4
shows the parameters of the PMSM used to simulate.
TABLE IV. PARAMETERS OF PMSM
V. CONCLUSION
In this paper analysis DTC method and a control
system of MRAS is introduced. DTC method is
designed for an efficient control of torque and flux
without changing the motor parameters and load,
which in this method the flux and torque can be
directly controlled with the inverter voltage vectors.
The DTC is use in a wide range.
MRAS method using adjustable model and the
reference model so that estimates the position and
speed of the rotor, which in this method use the motor
itself as the reference model. The simulation results
with MATLAB software indicate that speed sensor
less control of PMSM based on DTC method with
MRAS has preferable good dynamic performance,
speed estimation precise and fast torque response.
REFERENCES:
[1] M. Jafarboland, E. Babaei, "Sensorless
speed/position estimation for permanet
magnet synchronous machine via extended
Kalman filter",Jour. of Trans. on Elec. Tech.
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[2] L. Zhong, M..F. Rahman, W.Y. Hu, K.W.
Lim, “Analysis of direct torque control in
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IEEETrans. on Pow. Elec., Vol.12, No.3, pp.
528-536, 1997.
[3] Z. Tan , Y. Li, Z. Ji, ”Speed sensorless DTC
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based on a full-order MRAS method”, IEEE
Trans on Pow. Elec. ,pp.1202– 1206, 2000.
[4] S. Özçıra, N. Bekiroğlu, E. Ayçiçek “Speed
control of permanent magnet synchronous
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method”,IEEE/ISPE, pp. 268-272, 2008.
[5] M. F. Rahman, L. Zhong, E. Haque,
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motor”, Sch. ofElec. Eng. and Tele., The Uni.
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[6] D. Sun, F. Weizhong, H. Yikang, “Study on
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[9] F. M. Abdel-kader, A. El-Saadawi, A. E.
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[10] J. Luukko, “Direct Torque Control of
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[12] Tian Ming-xiu, Wang Li-mei, Zhen Jian-
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[14] Y. Liang, Y. Li, "Sensor less control of PM
synchronous motors based on MRAS method
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BIOGRAPHIES:
M. Pradeep kumar received the B.Tech Degree in
EEE from J.N.T.U- Hyderabad. He is currently
pursuing M.Tech in TKR Engineering College.
M. Chandramouly received the B.Tech Degree in
E.E.E from JNTU-Hyderabad and M.Tech Degree in
Energy Systems from JNTU-college of engineering
Hyderabad. He is currently working on effective use of
energy systems in JNTU Hyderabad.

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