sensor less control for im drives based on new speed identification scheme

8/14/2019 Sensor Less Control for Im Drives Based on New Speed Identification Scheme

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SENSORLESS CONTROL FOR INDUCTION MOTOR DRIVES BASED ONNEW SPEED IDENTIFICATION SCH EME

Shyh-Shing Perng*, Yen-Shin Lai**,Member, IEEE, and Chang-Huan Liu*,Member, IEEE* Dept. of Elect. Eng., National Taiwan Inst. of Tech., Taipei, Taiwan, R. 0.C.**Dept. of Elect. Eng., National Taipei Inst. of Tech., Taipei, Taiwan, R. 0.C.

Absibact - A sensorless controller, which is based upon theproposed synchronous speed identification scheme [l], forinduction motor drives is presented in the paper. Incomparison with previous results [2-31 which involvetemperature-sensitive parameters, including rotor and/orstator resistors, the proposed MRAS synchronous speedidentification scheme requires neither rotor time constantnor stator resistance in both reference and adjustablemodells.It is shown in this paper that the new sensorless controllerfor induction motor drives consists of feedfonvard control ofstator voltage[4] and the new MRAS synchronous speedidentification scheme, and does not invoke rotor resistanceand voltage sensors. Simulation and experimental resultswill be presented to confirm the theoretical analysis.

NomenclaturexU:D:

r referring to the rotor flux framed d-axis componentq q-axis components stator componentr rotor component

reference or com mand value of xestimated (calc ulated) or feedback value of xSymbols

synchronous speedrotor speedslip frequencydifferential operatorrotor resistancestator resistancerotor self-inductancestator self-inductancemutual inductancetotal leakage factor; o = I- ( ~,2,, L Arotor time constant; 7rsampling period of digitalLr/ Rr

implementationslipstator voltagerotor currentstator currentmagnetizing currentrotor fluxstator fluxI. I N T R O D U C T I O N

To improve the performance of dynamic response ofinduction motor drives, the conventional V/F controlscheme has been replaced by vector control [ 5 ] , whichrequires accurate information about the mechanical speedor position for field orientation. The field oriented controlcan be achieved at the cost of using additional shaftsensors, thereby increasing the size and reducing therobustness of the whole drive system.

To overcome these issues, sensorless control, withoutusing any shaft sensor, becomes a trend for the design ofinduction motor drives. A variety of methods have beenproposed which heavily rely upon plant parameters. Acomprehensive review of sensorless control of inductionmotor drives can be found in reference [6].Sensorless induction motor drives based upon the theoryof Model Reference A daptive System (MRAS) [7] providean alternative way for the development. However, themethod shown in [2] requires both rotor and statorresistors, and integral operation which involves initialvalue problem. Although, integration operation is notrequired in [8], rotor time constant wh ich is sensitive totemperature variation, is still necessary for the adjustablemodel.To deal w ith this problem, a novel sensorless controller[ l] based on model reference adaptive system has beenproposed and demonstrated by experimental andsimulation results. The proposed MRAS scheme requiresneither rotor time constant nor stator resistance in bothadjustable and reference models. Furthermore, since nointegral operation is required, the proposed schemeprovides wider bandwidth for speed control.Although rotor resistance is not required in the new

0-7E103-3823-5/97/$10.00@ 1997 IEEE 553 PCC-Nagaoka 97


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MRAS scheme [l], the vector controller still requires therotor resistance for the calculation of slip frequency. Anew sensorless controller, which does not require rotorresistance an d voltage sensors, for induction m otor drivecontrol will be presented. Simulation and experimentalresults will be presented to confirm the theoreticalanalysis.

II. THEORYA . A New MRAS Scheme

Although the new MRAS scheme [l] for synchronousspeed identification has been presented, a brief reviewrelevant to the development of the new sensorlesscontroller for induction m otor drives is given as follows.The m otor voltage referring to rotor flux frame, can bederived as follows.

Equations (2 ) an d (3 ) are substituted into (4), which isthe reactive power of machine, thereby resulting in (5) .

Substituting the stator flux equ ation shown in (6) into(5 ) , the reactive power equation can be rewritten as shownin (7).

According to the theory of MRAS , (4) an d (7 ) can beused as the reference and adjustable models, respectively,to id en tie the synchronous speed. The block diagram forthe new MRAS synchronous speed identification schem eis shown in Fig. 3. Notice that the reactive power shownin (4) and (7) does no t contain either rotor resistance no rstator resistance. Moreover, the calculations of reactivepower for both reference and adjust mod els as shown in (4)an d (7), respectively do no t require any integrationoperation.The proposed MRAS has been proved [l] to behyperstable using the theory of Hyperstability [9].Therefore, the synchronous speed is identified andconverges to the real value; more details about thedevelopment and proof can be found in [11.

Reference model

Excitation+

MechanismAdjustable model

Fig. 1. The proposed synchronous speed identificationscheme based upon MRA SB. Feedforward Control of Stator Voltage

The stator voltage equation of induction m otor drives is

Assume that the torque producing current, iL;,, isconstant and equals to its command value, i& , then inthe steady state the stator voltage comman d can be shownas follows.

*

v&* = R,i&* - w e * d s ) r & AV

where

(9)

C. Flux ControlThe well-known current m odel of rotor flux is

(11)xA j L - X - (I o e - w 7 ) X r7, 7,and the corresponding q-axis component is

Therefore , xqr is affected by the torque producingcurrent, i i , , and the following relationships result

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provided that the d erivative of .zq,equals to zero.z0 f A: = 0 , then 1 = I ( m e o r ) X d r9s L m

0 if A:,


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One of the features of the 80196 MC single-chip micro-processor is its embedded PWM generator whichgenerates the three-phase PW M gating signals accordingto the com mand voltage using traditional natural-sampledsinusoidal pulse-width m odulation (SPWM) technique.Several protection circuits are included in the single-chip microprocessor board and will cause trip wheneveron e of the events, including over voltage, under voltage,regeneration voltage, over current, and over load, occurs.The current detection circuits transform the load currentsignals into the acceptable voltage level, -0.5 - +5.5V, ofthe embedded A/D converter of 80196 MC single-chipmicroproce ssor. It is worthy of note that the samp ling timeof A/D s around 15 p seclchannel.Although the output pulses of incremental encoder ofinduction motor is not fed into the c ontroller, a decodingcircuit is built in th e single-chip microprocessor board formeasurem ent purpose and further applications.B. Sofmare Design

For the implementation of the sensorless controllershown in Fig. 3 using sofiware, it is necessary to derivethe discrete-time representations of the equations. Tosimplify the calculations of transforming the continuous-

,

time equations to the related discrete-time forms, the socalled backward rule of Eulers formula is consideredand is shown as follows [111.z - 1p = - T , z

Equation (19), derived by substituting (17) into (18),illustrates the associated discrete-time representation forproportional-integer (PI) control, using speed control asan example.

2 ( k+1)= ( k )+ k , + ,T)Amr k+1)- pAur k )where

field f- + tatorcoordi , natesoltage control

Fig. 3. System configuratio n of the sensorless contro ller

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3 Phase 220 V

I 1(for monitoring only)

Fig. 4. Hardwa re configuration of the implementation ofthe sensorless controllerC. Results

The simulation work has been carried out usingSimulinkTM nd the controller has been realized usingsoftware based on a single chip microprocessor, MC80196, board.Figs. 5 an d 6 illustrate the simu lation and experimentalresults using speed command equal to f l O O O rpm ande 0 0 rpm as e xamples, respectively. As shown in Figs. 5an d 6 , the simulation results agree with experimentalresults very well confirming the theoretical analysis.

0.00 2.00 4.00 6.00 0.00 2.00 4.00 6.00(a) t imes(sec) (b) t imes (sec)

0.00 2.00 4.00 6.00 0.00 2.00 4.00 6.00(c) times (sec) (d) t imes (sec)

10.00 7 10.00 75 00 5 000 00 0 00-5 00 -5 00

- 1000 + - 1 0 0 0 + , , , , , ,000 2 0 0 400 60 0 000 2 0 0 400 600

(e) t imes (sec) (f) t imes (sec)Fig. !5. Illustration of experimental and simulation results,+IO00 rpm , 2 Nt.-m;(a) speed response,simulation; (b). speed response, experiment ;(c)estimated speed, simulation; (d) estimated speed,experiment; (e) current for phase A, simulation;(Qcurrent for p hase A, experiment.

: I I I , ~ ,0.00

-200.00-400.00 -200.00-400.00

0.00 1.00 2.00 3.00 4.00 5.00(a) times(sec)I I I I I ,

0.03 1.00 2.00 3.00 4.00 5.00(b) times (sec); I l , 2;j I I I0.00-200.00 -200.00-400.00 -400.00

0.00 1.00 2.00 3.00 4.00 5.00 0.00 1.00 2.00 3.00 4.00 5.00(c) times (sec) (d) times (sec)10.001 10.001

-10.00+-, -10.00m,0.00 1.00 2.00 3.00 4.00 5.00 0.00 1.00 2.00 3.00 4.00 5.00(e) times (sec) (9 times (sec)Fig. 6 . Illustration of experimental and simulation results,+200 rpm , 2 Nt.-m;(a) speed response, simulation;

(b). speed response, experiment ;(c) estimatedspeed, simulation; (d) estimated speed, experiment;(e) current for phase A, simulation; (Qcurrent forphase A, experiment.IV. C O N C L U S I O N

A novel sensorless controller based on MRAS scheme,requiring neither rotor time constant nor stator resistancein both adjustable and reference models, for inductionmotor drives has been presented in this paper. Theproposed sensorless controller does not require rotorresistance, and thereby increasing the robustness toparameter va riations.The proposed sensorless controller is demonstratedusing simulation and experimental results confirming thetheoretical analysis.V. A C K N O W L E D G M E N T S

The authors gratefully acknowledge the financialsupport given by the National S cience Council under thegrants NSC8 6-2213-E-010-075 and NSC86-2622-E-011-005R.

VI. R E F E R E N C E S

1. S. S. Perng, Y. S. Lai ,and C. H. Liu, A novelsensorless controller for induction motor drives, toappear in EPE97.C. Schauder, Adaptive speed identification for vectorcontrol of induction motors without rotational

2.

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3.

4.

5.

6 .

7.8.

9.10 .

11 .

transducers, IEEE IAS Con$ Rec., pp. 493-499, 1989.(also see IEEE Trans. Ind. Appl., Vol. 28, No. 5 , pp .F. Z. Peng and T. Fukao, Robust speed identificationfor spee d-sens orless Vector control of inductionmotors, IEEE IAS Con$ Rec. , pp. 419-426, 1993.(also see IEEE Trans. Ind. Appl. ,Vol. 30, No. 5 , pp.T. Okuyama, N. Fujimoto, T. Matsui and Y. Kubota,A high performance seed control scheme forinduction moor without seed and voltage sensors,Con. Rec. of IEEE IAS Ann. Meet . , pp. 106-111,1986.F., Blaschke, The principle of field orientation asapplied to the new TRANSVECTOR closed loopcontrol system for rotating field machines, S iemensReview, Vol. 34, pp. 217-220, 1972.J. Holtz, Sp eed estimation an d sensorless control ofAC drives, Proceedings of IEEE IECON, Vol. 2, pp.Y. D. Landau, Adaptive control: the model referenceapproach, Marcel Dekker, Inc, New York, 1979.H. Tajima and Y. Hori, Speed sensorless fieldorientation control of the induction machine, IEEEIASConJ Rec., pp. 385-391, 1991.V. M. Popov, Hyperstability of automatic controlsystems, Springer-Verlag, New York, 1973.S. Shinnaka, A unified analysis on simultaneousidentification of velocity and rotor resistance ofinduction motors, Trans. IEE Japan, Vol. 113-D,G. F. Franklin, J. D. Powell, and M. L. Workman,Digital contro l of dynam ic systems, Addison-Wesley,Reading, Massachusetts, 1990.

1054-1061, 1992.)

1234-1240, 1994.)

649-654, 1993.

NO. 12, pp. 1483-1484, 1993.

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sensor less control for im drives based on new speed identification scheme

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