PMSM vector control performance improvement by using pulse with modulation and anti-windup PI

controller

Khalid CHIKH, Abdallah SAAD and Mohamed KHAFALLAH

Laboratory Building technologies and Industrial System Hassan ΙΙ University-ENSEM

Casablanca, Morocco genielectrique@gmail.com

Driss YOUSFI Department of Electrical engineering

Cadi Ayyad University-ENSA Marrakech, Morocco

dr_yousfi@yahoo.com

Abstract— This paper presents the simulation results in Matlab/Simulink of three versions of permanent magnet synchronous machine (PMSM) vector control. In order to choose the most suitable pulse width modulation (PWM) strategy for controlling the voltage inverter, in term of electromagnetic torque ripple minimization, three modulation techniques associated with the vector control are investigated i.e. sinusoidal PWM and Space Vector Modulation (SVM) with two types of symmetry. The computer simulation results demonstrate, also, the effectiveness of the anti-windup PI controller for the resolution of the saturation problem associated with classical PI controllers.

Keywords-PMSM;PWM;SVM;torque ripple; anti-windup

I. INTRODUCTION In recent years, the Permanents Magnet Synchronous

Machine (PMSM) is a real competitor of asynchronous machine in many applications. Free maintenance, robustness against environment, high efficiency, high power density, and high controllability are some of the PMSM characteristics responsible for its wide utilization in traction application such as hybrid and electric vehicles and in wind turbine [9].

To minimize the electromagnetic torque ripple, a study is presented to choose the most suitable PWM technique for controlling the voltage inverter. After simulation of the PMSM vector control with sinusoidal PWM, we developed and simulated this command by using two types of SVM techniques, and the difference between them is just in the adjacent vector sequence in each sector.

This paper, on the other hand, is focused on the comparison between two PI controller structures of electromagnetic torque associated to PMSM vector control. Classical PI controller is a simple method used in the control but there are many drawbacks of this regulator such as the sensitivity of performance to the system–parameter variations, load changes and saturation of its command in the dynamic state. In this work we purposed to solve the saturation problem of classical PI controller by an anti-windup PI controller of electromagnetic torque. Indeed, this anti-windup compensator is quite capable to reduce the peak and ripple in

electromagnetic torque at the dynamic state either by using SVM or sinusoidal PWM.

II. VECTOR CONTROL OF PMSM

A. Model of the PMSM The voltage and flux equations for a PMSM in the rotor

oriented coordinates d-q can be expressed as: . . .

. . . . .

Where Isd and Isq are the d - q axis stator currents, Rs is the stator resistance, is the flux linkage of the rotor magnets linking the stator, Ld and Lq are the d - q axis stator inductances, p is the number of pole pairs and is the mechanical speed.

This model is coupled, we must decouple it to obtain a new system by using compensation and decoupling techniques: .

.

And the electromagnetic torque equation (for ): Г

Finally, the motion equation is expressed as:

Г Г

B. Principle of Vector control The torque and flux of the PMSM are controlled through

stator current vector control. This vector is decomposed into a

978-1-61284-732-0/11/$26.00 ©2010 IEEE

torque and flux producing components in a frame, e.g. Isq and Isd respectively [4]. In this of vector control used is based to keep the cuand the voltage Vsq is used to control the rotat

In these conditions the relationship bettorque is linear. Г

The figure 1 show the principle of vector cand current sensors, from these signals the acontrol produce the PWM signals to controvoltage inverter according to the vector contr

Figure 1. Bloc diagram of vector control cont

C. PI anti-windup controller

In this vector control, the relationship linear and the torque depends just on curreason we proposed to improve the dynaPMSM by using a PI anti-windup controller loop.

Figure2. Bloc diagram of vector control with PI ant

For the conditioning technique proposed in

transfer function is given by the relationship:

The simulation results obtained by using tbetter than the results obtained in casecontroller.

III. SPACE VECTOR MODULA

With the development of dspace card, thhas become one of the most important PW

PI anti-windup controller structure

rotating reference paper, the strategy

urrent Isd equal zero tion speed.

tween current and

control with speed algorithm of vector ol the transitors of rol principle.

trolled PMSM

torque-current is rrent Isq. For this amic state of the just in current Isq

ti- windup controller

n [7] and [8], the

:

this controller are e of classical PI

ATION

he SVM technique WM methods for

voltage source inverter. It usecompute the duty cycle of the simplementation of PWM modudigital implementation and wioutput line to line voltages areThus SVM becomes a potentiain the torque signal [5].

The SVM principle is baseswitching period between two during times T1 and T2 , and twtime T0 [1].

Figure3. Sp

According to the symmetry in each sectors, there are many proposed to study two different

A. Symmetrical SVM

The bloc diagram of the (DS1104) use a special symmeand signal to start or stop the S

Figure4. Bloc diagr

1

e

es the space vector concept to switches. It simplifies the digital ulations. An amplitude for easy ide linear modulation range for e the notable features of SVM. al technique to reduce the ripple

ed on the switching during one adjacent active vectors V1 , V2

wo zero vectors V0 , V7 during

pace vectors

of active and zero vectors used types of SVM. In this paper we

t symmetries.

SVM implanted in DSP card etry, it inputs are T1 , T2 , sector VM.

ram of DS1104 SVM

This bloc use a symmetrical symmetry shown in the figure5.

Figure5. Bloc diagram symmetry of DS1104 SVM

The vector _ é is commonly split into two nearest adjacent voltage vectors and zero vectors in an arbitrary sector. For example during one sampling interval Tp, vector _ é in the first sector can be expressed as:

_ é 1 2 2 2 2 2 2

Where

B. Asymmetrical SVM

In the literature, there are also an asymmetrical SVM, in this work we present in figure 6 commutation signals in the first sector of the higher transistors inverter [5].

Figure6. Bloc diagram symmetry of asymmetrical SVM

During one sampling interval Tp, vector _ é in the first sector can be expressed as:

_ é 1 2 2

Where The commutation losses with asymmetrical SVM (five commutations) are more than the case of symmetrical SVM (four commutations).

IV. SIMULATION RESULTS

The model of the PMSM, vector control, inverter voltage, vector modulation techniques and sinusoidal PWM are developed in MATLAB SIMULINK to examine the dynamic and static performance of the machine control. First, we present the simulation results of the vector control with classical PI torque controller using on the one hand, the sinusoidal PWM for direct control of the voltage inverter and in the other hand we will use two techniques for space vector modulation (SVM) already presented. To examine the robustness of the control we have subjected the machine to a test of speed and torque variation, in the beginning the machine starts under no load and a speed of 1000 rpm and drives a DC machine corresponds to a load torque of 0.12 Nm in no load, at t = 1.5 seconds a speed of 100 rpm is applied, and 0.55 seconds after we switch to the load test, for this and from the time t = 2.05 seconds we apply at the same time a speed of 1000 rpm and a rated torque of 0.8 Nm.

Second, we replace the classical PI controller by an anti-windup PI controller in order to overcome the saturation problem associated with this first during the transient and, therefore, causes a peak and oscillations of the electromagnetic torque at startup of the PMSM and at the moments of speed variations. To compare the simulation results, we test the dynamic of anti-windup PI controller under the same operating conditions with a classical torque PI controller.

Indeed, the simulation results show that the anti-windup PI controller is greatly improves the transient state, as and from the figure (couple) it is clear that the peak torque decreased from 3.5 Nm to 1.7 Nm and the torque oscillations are damped due to structure stabilizing of anti-windup controller.

V. CONCLUSION

A vector control simulation results of the PMSM with tree PWM techniques and two PI controllers structure is presented.

In term of electromagnetic torque ripple, the asymmetrical SVM (THD= 3.39 %) is more efficient than the symmetrical SVM (THD= 3 %), and also the commutation losses are smaller in case of asymmetrical SVM.

The simulation results of this study shows that, plus de execution time of the sinusoidal PWM is very small than the SVM, the electromagnetic torque ripple is also small by using sinusoidal PWM (THD= 2.24 %). Indeed, in case of PMSM vector control, the sinusoidal PWM is more efficient than SVM. But in case of direct torque control, the SVM improve significantly the electromagnetic torque ripple.

The second target of this work was achieved by using the anti-windup controller, who is quite capable to decrease the peak torque in the transient state. Indeed, this corrector resolves the saturation problem of the classical PI controller.

V0

T0/2 T0/2 T2 T1 T0/2 T0/2 T1 T2 Tp Tp

SPWM1

SPWM3

SPWM5 V1 V2 V7 V7 V2 V1 V0

Tp/2 T2/2 T1/2

V1 V2 V7 V7 V2 V1

SPWM1

SPWM3

SPWM5

T1/2 T2/2 T0 Tp/2

TABLE Ι. MOTOR PARAMETRS:

Rated output power (Watt) 500

Rated phase voltage (Volt) 190

Magnetic flux linkage (Wb) 0.052

Poles 3

Rated torque (Nm) 0.8

Maximum speed (rev/min) 6000

Stator resistance (Ω) 1.59

d-axis inductance (mH) 3.3

q-axis inductance (mH) 3.3

Inertia (Kg.m2) 0.003573

TABLE ΙΙ. SIMULATION PARAMETRS:

DC bus voltage (Volt) 60

Sample time (Second) 5.10-5

Modulation frequency (Khz) 10

REFERENCES [1] Lixin Tang, Limin Zhong, Muhammed Fazlur Rahman and Yuwen Hu

“A Novel Direct Torque Control for Interior Permanent-Magnet Synchronous Machine Drive With Low Ripple in Torque and Flux—A Speed-Sensorless Approach”, IEEE Transactions on industry applications, VOL. 39, NO. 6, NOVEMBER/DECEMBER 2003, pp…-..

[2] Jean-Paul-Louis, Claude-BERGMANN "Numerical control of synchronous machines", Tech Engineering, Electrical Engineering Treaty, DOC 3644.

[3] Alessandro Lidozzi, Luca Solero, Fabio Crescimbini, Augusto Di Napoli “ SVM PMSM drive with low resolution hall-effect sensors”, IEEE Transaction on power electronics , Vol.22, NO.1, January 2007.

[4] S. Vaez-Zadeh, E.Jalali “Combined vector control and direct torque control method for high performance induction motor drives”, ScienceDirect, Energy Conversion and Management 48 (2007) 3095-3101.

[5] Tian-Jun Fu, Wen-Fang Xie “A novel sliding-mode control of induction motor using space vector modulation technique”, ISA Transaction 44 (2005) 481-490.

[6] S. Rafa, H. Zeroug, L. Hocine, K. Boudj''Simulation on Matlab / Simulink and implemented on DSP / FPGA vector control of permanent magnet synchronous machine (PMSM) fed by an inverter voltage with Space Vector Modulation (SVM),''Industrial Electrical Systems Laboratory. University of Science and Technology Houari Boumedienne.

[7] A. Ebach, M. T. Lamchich,''Mr. Cherkaoui direct torque control of induction motor speed control system with anti-windup'', Laboratory of Electronics and Instrumentation, Faculty of Science Semlalia, University Cadi Ayyad-Marrakech, Morocco.

[8] Mr. Chenani, S. Doubabi''control with anti-windup compensator of a micro hydropower plant,''Laboratory of Automation and Computer Engineering, Faculty of Science and Technology, University Cadi Ayyad, Marrakech, Morocco.

[9] Ravindra Kumar Sharma, Vivek Sanadhya, Laxmidhar Behera and S Bhattacharya ‘‘Vector control of permanent magnet synchronous motor’’, 978-1-4244-2746-8/08/&25.00, 2008 IEEE.

[10] K. Hakiki, A. Meroufel, V. Cocquempot and M. Chenafa ‘‘A New Adaptive Fuzzy Vector Control for Permanent Magnet Synchronous Motor Drive’’,18th Mediterranean Conference on Control & Automation Congress Palace Hotel, Marrakech, Morocco June 2010.

[11] Jun Liu, Meng-zhi Huang and Yang Wang ‘‘Research on Vector-Control System of PMSM Based on Internal Model Control of Current Loop’’, Second International Workshop on Computer Science and Engineering, 2009.

[12] Junjie Ren, Hui Feng, Hongying Ren and Yi Huang ‘‘Simulation of PMSM Vector Control System Based on Propeller Load Characteristic’’, International Conference on Intelligent Control and Information Processing August 13-15, 2010 - Dalian, China.

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Figure.9: Stator current Speed in case of vector control with sinusoidal PWM (a) classical PI controller (b) anti-windup PI controller

Figure.7: Speed in case of vector control with sinusoidal PWM (a) classical PI controller (b) anti-windup PI controller

Figure.8: Electromagnetic torque in case of vector control with sinusoidal PWM (a) classical PI controller (b) anti-windup PI controller

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Figure.10: Current THD in case of vector control with sinusoidal PWM (a) classical PI controller (b) anti-windup PI controller

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Figure.11: Speed in case of vector control with symmetrical SVM (a) classical PI controller (b) anti-windup PI controller

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Figure.12: Electromagnetic torque in case of vector control with symmetrical SVM (a) classical PI controller (b) anti-windup PI controller (a) (b)

Figure.13: Stator current in case of vector control with symmetrical SVM (a) classical PI controller (b) anti-windup PI controller (a) (b)

Figure.14: Current THD in case of vector control with symmetrical SVM (a) classical PI controller (b) anti-windup PI controller (a) (b)

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Figure.15: Speed in case of vecto(a)

Figure.16: Electromagnetic torque in case o(a)

Figure.17: Stator current in case of ve(a)

Figure.18: Current THD in case of vector(a)

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