This ppt shows the modelling and simulation of permanent magnet synchronous motor by using torque control method. And this is the most advanced and soffestigated method to control the pmsm motors.

1. Guide : Mr. M. SRINIVASA RAO
ASSO. PROFFESOR

2. Abstract
» The use of Permanent Magnet Synchronous Motors (PMSM)
combined with Direct Torque Control (DTC) scheme offers
many opportunities to achieve rapid and accurate torque
control in servo applications.
» The DTC is implemented by selecting the proper voltage
vector according to the switching status of inverter which
was determined by the error signals of reference flux linkage
and torque with their measured real values.
» Here, model of Interior type of PMSM is studied. Its
performance for various motor parameters is tested on
MATLAB-SIMULINK.

3. » DTC was proposed by TAKAHASHI and NOGUCHI in
1986 for application in Induction Motors. Their idea
was to control the stator flux linkage and the torque
directly, not via controlling the stator current.
» This was accomplished by “ OPTIMUM SWITCHING
TABLE”.
» M. F. RAH MAN investigation of direct torque control
(DTC) for PMSM drives.
» It was mathematically proven that the increase of
electromagnetic torque in a PMSM is proportional to
load angle.
Literature Review

4. » Control of the amplitude and rotating speed of the stator
flux linkage are analyzed.
» Torque response with DTC was found to be 7 times faster
than with PWM current control.
» JAWAD FAIZ introduced a new analytical technique for
generating the reference flux from the torque. It is shown
how the maximum torque per ampere (MTPA) can be
followed in the control process.
» Salient-pole PMSM motor is simulated using the
maximum torque per flux (MTPF) and the reference flux
determined.

5. » In Permanent magnet synchronous motors the
rotor winding are replaced by permanent
magnets.
» A permanent magnet synchronous machine is
basically ordinary AC machine with winding
distributed in the stator slots so that the flux
created by stator current is approximately
sinusoidal.
» Permanent magnet drives are replacing classic DC
and induction machine drives in a variety of
industrial applications such as industrial robots
and machine tools.
Introduction to PMSM

6. » Two types of permanent magnet ac motor drives are
available :
1) PMSM drive with a sinusoidal flux distribution.
2) Brushless dc motor drive with a trapezoidal flux
distribution.
Xq>Xd
There are two major topologies of rotors of PMSMs

7. » The modeling of PM motor drive system is required for
proper simulation of the system.
» The d-q model has been developed on rotor reference
frame as shown in figure:
δ
Modelling of PMSM

8. Stator and Rotor flux linkages in different frames
» The model of PMSM without damper winding has been
developed on rotor reference frame using the following
assumptions:
» Saturation is neglected.
» The induced EMF is sinusoidal
» Eddy currents and hysteresis losses are negligible.
» There are no field current dynamics.

9. » The angle between the stator and rotor flux linkage δ is the
load angle when the stator resistance is neglected.
» In the steady state, δ is constant corresponding to a load
torque and both stator and rotor flux rotate at
synchronous speed
» In transient operation δ varies and the stator and rotor flux
rotate at different speeds.
» Since the electrical time constant is normally much
smaller than the mechanical time constant, the rotating
speed of the stator flux with respect to the rotor flux can
be easily changed

10. » Voltage equations in rotor reference frame are given by
» The flux Linkages are given by
» Substituting the flux linkages in the above voltage equations
» Arranging above equations in matrix form
qdrqqq iRV  
Motor Equations
dqrddd iRV  
qqq iL
fmddd LiL  
qqfddrqsq iLiLiRV   )(
)( fddqqrdsd iLiLiRV  




























f
fr
d
q
dsqr
drqs
d
q
i
i
LRL
LLR
V
V





11. » The developed motor torque is being given by
» Substitution of the flux linkages in terms of the inductances and current
yields
» The mechanical torque equation is
» The rotor mechanical speed is given by
» id and iq in terms of Im
» The electromagnetic torque equation is given by
 dqqde ii
p
T  






22
3
 dqqdqfe iiLLiPT )(
2
3
 
dt
d
JBTT m
mLe

 
dt
J
BTT mLe
m  




 



  













cos
sin
m
d
q
I
i
i
  



 sinI2sinILL
2
1
2
p
2
3
T mf
2
mqde

12. » V/F control is among the simplest control. The control is an
open-loop and does not use any feedback loops.
» The idea is to keep stator flux constant at rated value so
that the motor develops rated torque/ampere ratio over its
entire speed range.
CONTROL SCHEMES FOR PMSM
Variable Frequency Control
Vector Control
FOC DTC
Scalar Control
V/F Control

13. Field Oriented Control
Vector Control
Direct Torque Control
DTC vs FOC

14. There are 3 signals which affect the control
action in a DTC system;
» Torque –
» The amplitude of the Stator Flux linkage –
» The angle of the resultant flux linkage vector –
(angle between stator flux vector and rotor flux
vector)

16. » The stator flux linkage of PMSM is
» Neglecting the stator resistance, the stator flux
linkage can be directly defined as
dtRiV sss )(  
0  stsss dtiRtV 
0 stss tV 
Amplitude Control of Stator Flux
Linkage (Ψs)

17. 0 stss tV  0 stss tV 
HB- hysteresis-band width

18. HB- hysteresis-band width
0 stss tV 

19. Flux and torque variations Due to
Applied Voltage vector

20. » For counter-clockwise operation,
» if the actual torque is smaller than the reference, the
voltage vector that keeps Ψs rotation in the same direction
is selected.
» Once the actual torque is greater than the reference, the
voltage vectors that keep Ψs rotation in the reverse
direction are selected
» By selecting the voltage vectors in this way, the stator flux
linkage is rotated all the time and its rotational direction is
determined by the output of the hysteresis controller for
the torque.
The control of the rotation of stator
flux linkage

21. If the actual flux linkage is smaller than the
reference flux value then Ø = 1.
The same is true for the torque.
Working principle of Direct Torque
Control for PMSM

22. » When an upper transistor is switched on, i.e., when a, b or
c is “1”, the corresponding lower transistor is switched
off, i.e., the corresponding a’, b’ and c’ will be “0”.
VOLTAGE SOURCE INVERTER

23. switching voltage vectors
STATE Sa Sb Sc
V0 OFF OFF OFF
V1 ON OFF OFF
V2 ON ON OFF
V3 OFF ON OFF
V4 OFF ON ON
V5 OFF OFF ON
V6 ON OFF ON
V7 ON ON ON

24. » There are eight possible combinations of on and off patterns for
the upper power switches and lower power devices.
» STATE 1: ( 000 ) STATE 2: ( 100 )
» STATE 3: ( 110 ) STATE 4: ( 010 )
0,0,0 00  coba VVV
0V,VV,VV codc0bdc0a 
0V,0V,VV co0bdc0a 
0,,0 00  codcba VVVV

25. dccodc0b0a VV,VV,0V  dcco0b0a VV,0V,0V 
dcco0bdc0a VV,0V,VV  dccodc0bdc0a VV,VV,VV 
» STATE 5: ( 011 ) STATE 6: ( 001 )
» STATE 7: ( 101 ) STATE 8: ( 111 )

26. Vao = Vdc ; Vbo = Vdc ; Vco = 0
The space vector is Vs = Vao + Vbo ej2/3 + Vco e-j2/3
Substituting the values of Vao, Vbo and Vco:
Vs = Vdc(1/2 + j 3/2) (in rectangular form)
= Vdc 600 (in polar form)
Similarly the switching vectors can be computed for the
rest of the inverter switching states.
Computation of Switching vectors
For state-2 (+ + -):

27. Different switching states & corresponding space
vectors.
Switching state
[a b c]
Space Vector Vs
Rectangular form Polar form
V0 = [0 0 0] Vdc (0 + j0) 0 0
V1 = [1 0 0] Vdc (1 + j0) Vs 0
V2 = [1 1 0] Vdc (0.5 + j ) Vs 60
V3 = [0 1 0] Vdc (-0.5 + j ) Vs 120
V4 = [0 1 1] Vdc (-1 + j0) Vs 180
V5 = [0 0 1] Vdc (-0.5 – j ) Vs 240

28. 





























cn
bn
an
q
d
v
v
v
V
V
2
3
2
3
0
2
1
2
1
1
3
2
22
qdref vvV 
ftt
v
v
d
q






 
2tan 1

» To implement the Space Vector PWM, the voltage
equations in the abc reference frame can be transformed
into the stationary d-q reference frame that consists of the
horizontal (d) and vertical (q) axis.

29. » The three-phase variables are transformed into d-q
axes variables with the following transformation
dtirv dsdd )(   dtirv qsqq )( 
)( 22
qds  
)(
2
3
dqqde iipT  
Flux and Torque Estimator

30. Trajectory of stator flux vector in DTC
control
Inverter voltage vectors and corresponding
stator flux variation in time Δt
It receives the input signals Ф, τ θ and generates the
appropriate control voltage vector (switching states Sa, Sb, Sc)
for the inverter
Switching Table

31. Switching table of inverter voltage
vectors

32. Basic block diagram of DTC for PMSM

33. Digital outputs of the flux and torque controller have
following logic:
FEATURES, ADVANTAGES AND DISADVANTAGES
OF DTC :

34. Simulink Block of the DTC for PMSM

35. Simulink Block of the DTC for PMSM

36. 1. Simulink model
of the controller
2. Sub block of the
direct torque control
switching.

37. 1.
2.
Study of effect of magnet strength and change in M.I on
PMSM under no load and full load
Electromagnetic torque (1) and speed (2) for Ipm = 1.4 A under noload:

38. 1.
2.
Electromagnetic torque (1) and speed (2) for Ipm = 1.4 A under full load:

39. 1.
2.
Electromagnetic torque (1) and speed (2) for Ipm = 1.8 A under noload:

40. 1.
2.
Electromagnetic torque (1) and speed (2) for Ipm = 1.8 A under fullload:

41. 1.
2.
Electromagnetic torque (1) and speed (2) for M.I = 0.03 under noload:

42. 1.
2.
Electromagnetic torque (1) and speed (2) for M.I = 0.03 under fullload:

43. 1.
2.
Electromagnetic torque (1) and speed (2) for M.I = 0.09 under noload:

44. 1.
2.
Electromagnetic torque (1) and speed (2) for M.I = 0.09 under fullload:

45. Torques produced in the PMSM
Excitation torque with varying the Ipm values

46. Induction torque with varying the Ipm values
Reluctance torque with varying the Ipm values

47. Study of effect of Ipm, change in M.I on PMSM with DTC for torques

48. » DTC strategy realizes almost ripple-free operation for the
electromagnetic torque and speed under no-load as well
as full-load for different values of Ipm and M.I.
» When magnetic strength value (Ipm) increases from 1.4 to
2.2, excitation torque and reluctance torque are increased
and induction torque remains unchanged.
» With the increase in moment of Inertia the response time
of drive without DTC is more, and with DTC, the drive has
smooth synchronization process.
» The simulation results verify the proposed control and also
shown that the transient response of torque and speed of
drive with DTC is much faster than the drive without DTC
Results and Conclusions