dSpace DS-1104 implementation of Field Oriented ...

th 10 10th International International conference conference on on Sciences Sciences and and Techniques Techniques of Automatic control & computer engineering of Automatic control & computer engineering December December 20-22, 20-22, 2009, 2009, Hammamet, Hammamet, Tunisia Tunisia

dSpace DS-1104 implementation of Field Oriented Control for Induction Motor T. Gallah, R. Trabelsi, R. Abdelati, A. Ben Ali and A. Khedher, Monastir Engineering School, Ibn Aljazzar City, 5000 Monastir-TUNISIA Email: [email protected], [email protected] Abstract: In this paper, we present practical results of Field-Oriented Control (FOC) for an induction motor via a voltage static inverter controlled by space vector modulation strategy. The design, analysis, and implementation for a 1.5-kW induction motor are completely carried out using a dSPACE DS1104 around a PowerPC, a digital signal processor (DSP) based real-time data acquisition control (DAC) system, and MATLAB/Simulink environment. Keywords: Induction motor, FOC, Experimental implementation, Card Dspace 1104 List of symbols V sαβ : stator voltages in reference frame αβ , i sαβ

: stator currents in reference frame αβ ,

ϕ rαβ : rotor fluxes in reference frame

αβ ,

R s , R r : stator and rotor resistances, L s , L r : stator and rotor cyclic inductances,

: stator-rotor cyclic mutual inductance, : Blondel coefficient, ωs : angular speed of the rotating field referred to the stator, ωr : angular speed of the rotating field referred to the rotor, p : Laplace operator , M

σ

J : moment of inertia, f : damping coefficient, n p : pairs pole number Tem , TL : electromagnetic and load torque. STA'2009-RME-718, pages 1562-1570 Academic Publication Center of Tunis, Tunisia

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STA’2009, MRE Machines et Réseaux Electriques, 9

1. Introduction Induction motors have found considerable applications in industry due to their reliability, ruggedness and relatively law cost [1,3]. Two principal elements have contributes at this progress: the development of the power electronics and the appearance of digital signal processor. Our application is made on a DS1104 controller board which is a compact single-board solution based on the floating point PowerPC (250 MHz). It requires only a half length slot and is suitable for many control applications, such as robotics, positioning systems, motor control and hardware in the loop simulation [2,3,6]. The DS1104 combines the TMS320 F240. This subsystem provides more complex functions like PWM, capture, timers, and I/O DSPACE panel. The DS1104 is designed for a standard PC environment, but can also be connected to a workstation via the network kit. The DSPACE© system including interface boards can be programmed in MATLAB/SIMULINK© environment and in C language. In the aim to be familiarized with this DS1104’s workspace and the DSPACE interface, we have interested to the closed loop control of an induction motor, by programming the suitable algorithm in the SIMULINK environment. PWM signals are delivered from DS1104’s interface to our inverter and signal of control variable are captured and studied. The paper is organized as follows. The second section relates to the modelling of an induction motor. The field oriented control (FOC) structure is presented in the third section. In section four we present our test bench. Experimental results are given in section six. Finally, we present concluding remarks and perspectives.

2. Induction Motor Model The induction motor can be described by five non-linear differential equations with four electrical variables, one mechanical variable and two control variables such as [1,4]:

  -γ   i sα      0 d  i sβ    = dt  ϕ rα   M  ϕ   Tr  rβ    0  

M σLs Lr Tr

0

M ω σL s Lr

-γ 0

1 Tr

M Tr

ω

M  ω σL s Lr   M  σLs Lr Tr    -ω   1   Tr 

 1   i sα   σLs    i sβ     + 0  ϕ rα   ϕ   0  rβ   0 

 0   1   v sα    σL s   v sβ  0  0 

(1)

dSpace DS-1104 Implementation of FOC for induction Motor

γ=

with

1 σL s

 M   R s +  L  r 

2   M2  Rr  , σ = 1 − Ls Lr   

(3)

and Tr =

Lr Rr

The mechanical equation is given by:

J

dω r + f ωr = T em − T r dt

(2)

The expression of the electromagnetic torque is written as follows: T em =

3n p M 2 Lr

(ϕ rα i sβ − ϕ rβ i sα )

(3)

3. The Field Oriented Control (FOC) principle The field-oriented control theory applied to the induction motor aims at obtaining a decoupled control of the machine flux and torque by referring the (α,β) machine model to a rotating (d,q) reference frame aligned on rotor flux vector whose magnitude and position are provided by a flux estimator. The d-axis component of the stator current vector controls the flux, meanwhile, the q-axis current component controls the speed. The current control forms an inner loop of the overall control system, receiving the reference currents from the outer loops (flux loop and torque/speed loops) [6] . The principle of the FOC is based on the adaptation of the d-axis Park's frame according to the rotor flux level [1,2,3], that allows to write:

ϕ rd  ϕ rq

= ϕr

(4)

= 0

In these conditions, one can write:

 0 =  0 = 

R r i rd +

d dt

φ rd

(5)

R r i rq + ω r φ rd

while the expression of the electromagnetic torque is given by: Tem =

3 2

np

M Lr

φ rd i sq

(6)

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The concept of the proposed FOC structure is based on the determination of four transfers functions. To determine these transfers functions, we consider the following system:

dϕ sd  V sd = R s i sd + dt − ω s ϕ sq   V = R i + dϕ sq + ω ϕ s sq s sd  sq dt

( 7)

Where d-axis and q-axis flux components are expressed by:

M  ϕ sd = σ L s i sd + L ϕ r r  ϕ = σ L i sq s sq 

(8)

The synchronous speed and rotor flux level one expressed as follows: M i sq ωs = ωr + Tr

ϕr

d 1 ϕr = − (ϕ r − Misd ) dt Tr

(9) (10)

After some development using the Laplace transformer and relations (7 ) to (8 ), we rewrite the stator voltage system given by equation ( 11).

  Vsd =  σ    V =  σ  sq 

M 2 M  ) Rr )  isd − ϕ rd − ωsσ Tr Lr Lr 

Ls isq

M 2 M  Ls p + ( Rs + ( ) Rr )  isq + ωsϕ rd + ωsσ Lr Lr 

Ls isd

Ls p + ( Rs

+(

(11)

Designing by

Vsd = Vsd 1 + Vsd 2  Vsq = Vsq1 + Vsq 2 The quantities Vsd 2 and Vsq 2 represents the terms compensation wich can be used to reconstruct the stator voltage. The components Vsd 1 and Vsq1 are depending on the tow components isd and isq of stator current vector.

dSpace DS-1104 Implementation of FOC for induction Motor

 M 2   Vsd 1 =  σ Ls p + ( Rs + ( Lr ) Rr )  isd     M V = − ϕ rd − ωsσ Ls isq  sd 2 Tr Lr

(5)

 M 2   Vsq1 =  σ Ls p + ( Rs + ( Lr ) Rr )  isq     M V = ω ϕ + ω σ L i s s sd  sq 2 Lr s rd

4. Test bench

The supply power includes the redressed DC voltage of 500 V, which is smoothed by a simple LC filter and the three phase voltage source inverter with PWM based on insulated gate bipolar transistors (IGBT’s). Our application is made on a DS1104 controller board, which is connected to a PC environment and is a compact single-board solution. The DS1104 R&D controller board is one of the board’s incremental encoder interfaces picks up the encoder signal of the motor, while two converters are required to analyse the motor currents. The controller board calculates the control algorithm on the basis of the measured values and determines the corresponding pulse width modulation (PWM). The three-phase PWM signals are generated on the board’s DSP subsystem and determine the converter’s output voltage and frequency [4]. Power PC

Encoder

Encoder

Voltages acquisition card

2 ADC

Currents acquisition card

2 ADC TMS320 F240

PWM card interface

Control Desk

Fig.1. DS1104’s controller board

PWM 0-5

D S P A C E C A R D 1 1 0 4

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Fig.2. View of the experimental testing ground for IM drive system 6. Experimental implementation For the implementation of the proposed FOC for induction motor drive, an experiment has been carried out (Fig. 3). The FOC algorithm is programmed with Matlab-Simulink and downloaded in the dSpace DS-1104 control board, offering a four-channel 16-bit (multiplexed) ADC and four 12-bit ADC units. A sampling period of 200 µs is selected and the insulated gate bipolar transistors (IGBTs) are working at a switching frequency of 5 kHz with a dead time of 2 µ s . The output control signals of the Slave I/O PWM are of TTL level 5 V, whereas IGBTs of the static inverter must receive signals of 15 V. An adaptation interface board using the integrated circuit IR2130 from International rectifier is realized [4,5,6].

Fig.3. Bloc diagram of the field-oriented-control algorithm using Matlab/Simulink.

dSpace DS-1104 Implementation of FOC for induction Motor

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300 Vs , Vs (V) α β 200 100 0 -100 -200 -300 t (s) -400 0

5

10

15

20

25

30

35

40

Fig. 4 : Stator voltage response 300 Vs , Vs (V) α

β

200 100 0 -100 -200 -300 t (s) 37.85

37.9

37.95

38

38.05

38.1

38.15

38.2

38.25

Fig. 5 : ZOOM of Fig.4 around 38.05 s 15 is , is (A) α

β

10 5 0 -5 -10 t (s) -15 0

5

10

15

20

25

Fig. 6 : Stator Current response

30

35

40

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1.5 is , is (A) α

β

1 0.5 0 -0.5 -1 -1.5

t (s) 22.55

22.6

22.65

22.7

22.75

22.8

22.85

Fig. 7 : ZOOM of Fig.6 around 22.7 s 0.9 φ , φ r

r-ref

(Wb)

0.8

0.7

0.6

0.5 t (s) 0.4 0

5

10

15

20

25

30

35

40

Fig 8: Rotor flux 260

ω ,ω r

ref

(rd/s)

240

220

200

180 t (s) 160 0

5

10

15

20

25

30

Fig. 9 : Rotor Speed response via FOC method

35

40

dSpace DS-1104 Implementation of FOC for induction Motor

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The obtained results are shown in figures 4 to 9. The rotor flux is kept constant at its rated value 0.81 wb and the reference speed is 200 rd/s. It’s clear that this strategy of control leads to satisfactory results. One according to the experimental results that the variations of the real and reference speed and flux present a simular dynamic in terms of continuation and establishment.

6. Conclusion This work has been devoted to the real time control of an induction motor. A FOC method combined to the space vector modulation incorporating the PI controller is experimentally implemented using a digital signal processor board DS 1104 for a laboratory 1.5Kw induction motor. Our presented test bench has registered a good performances on the capture of different control variables such as rotor speed and stator currents. Our future work will be interested to the experimental implementation control of the generalized predictive Control of the induction machine. References [1] T. Gallah, A. Khedher, M. F. Mimouni and F. M’sahli, «Theoretical comparison between Field Oriented and Generalized Predictive Control for an Induction Motor », International Journal on Sciences and Techniques of Automatic control, IJ-STA, Vol. 1, No.1, pp 43-60, June 2007. [2] A Makouf, M. E. H. Benbouzid, D. Diallo, and N. E. Bouguechal « A Practical Scheme for Induction Motor Speed Sensorless Field-Oriented Control », IEEE Transaction onEnergy conversion, vol.19, No. 1, March 2004. [3] Khedher A., Mimouni M. F., Derbel N. and Masmoudi A., « Robust Field Oriented Control Analysis of an Induction Motor Using an Adaptive Flux Observer Based on Sliding Mode Methodology ». IEEE-MESM’2003, pp.186-190, January 2004, Sharjah, UAE.

[4] M. Jemli , H. Ben Azza and M. Gossa, « Real-time implementation of IRFOC for Single-Phase Induction Motor drive using dSpace DS 1104 control board ». Simulation Modelling Practice and Theory 17, pp.1071–1080, March 2009. [5] Ouhrouche M.A., Léchevin N. and Abourida S., «RT-Lab Based Real-Time Simulation of a Direct Field-Oriented Control for a Induction Motor », Electrimacs 2002, August 2002. [6] R. Bojoi, A. Tenconi, G. Griva, and F. Profumo, «Vector Control of Dual-Three-Phase Induction-Motor Drives Using Two Current Sensors», IEEE Trans. on Industry Applications, vol. 42, no. 5, pp. 1284-1292, Septembre/October 2006.