synopsis presentation 3

8/7/2019 SYNOPSIS PRESENTATION 3

1/12

HARMONIC MITIGATION IN AC-DC CONVERTER

FOR VECTOR CONTROLLED INDUCTION MOTOR

UNDER GUIDANCE OF SUHANI GUPTA

Mr. SANJIBA BISOYI SUSHANT VERMA

EE DEPARTMENT

VII SEMESTER


2/12

INTRODUCTIONy Induction Motor is widely used as it offers improved

efficiency, low cost and energy savings.

y Incorporation of flexible characteristic of DCMACHINE i.e. armature & field currents aredecoupled.

y This feature is incorporated with the help of VECTOR

CONTROL technique.y A 6-pulse AC-DC converter is used to feed power to the

VCIMD.


3/12

y

The diode bridge rectifier used in the converter suffersfrom operating problems such as:

y Poor power factor

y Injection of harmonic currents into the ac mains

y

Equipment overheating due to harmonic currentdistortion, etc.

y These harmonics need to be mitigated.

y THD (total harmonic distortion) should be minimum.

It is the ratio of sum of all harmonic components to thepower of fundamental frequency.


4/12

What is VECTORCONTROL?

y It is a technique of variable frequency control, whichcontrols the Torque & hence the Speed by controllingthe Current.

yThe stator phase currents are measured and convertedinto corresponding complex(space) vector.

y This complex vector is then transformed to acoordinate system rotating with the rotor of the

machine.y Then the rotor flux linkage is estimated by multiplying

the stator current vector with magnetizing inductanceLm.


5/12

y Using this rotor flux linkage vector, the stator currentvector is further transformed into the coordinatesystem where the real x-axis is aligned with the rotorflux linkage vector.

y Now the real x-axis component of the stator currentvector in the rotor flux oriented coordinate system can

be used to control the rotor flux linkage and theimaginary y-axis component can be used to control themotor torque.


6/12

6-pulse AC-DCCONVERTER:y The ac-dc converter feeds power to the VCIMD.

y It consists of 6-pulse diode bridge rectifier, energy

storage element at dc link, 3 phase voltage sourceinverter.

y Near unity power factor is achieved.

y Very low value of total harmonic distortion is also

obtained.y Good regulation of dc link voltage.

y Disadvantage is high cost.


7/12

Circuit diagram of6-pulse diode

rectifier fed VCIMD


8/12

AC mains current waveform of VCIMD fed by 6-pulse

rectifier along with its harmonic spectrum at full load


9/12

PROJECT STRATEGY:Study Phase: Study of theoretical background

Modelling Phase: Circuit designing

Analytical Phase: Analysis of the Output plot.

VII Semester: Study of theoretical background &modeling of the 6-pulse ac-dc converter.

VII Semester: Analysis of the output plots & itsoptimization.


10/12

Conclusion:The 6-pulse ac-dc converter will be designed and

modeled with reduced harmonics for vector controlled

3 phase squirrel cage induction motor. This will have alow value of THD along with better regulation of dclink voltage. Near unity power factor will also beachieved. A high pulse ac-dc converter is complex inconstruction though it is simple to implement. Theproposed harmonic mitigator along with the VCIMDwill be simulated in the MatLab environment.


11/12

Literature survey

:

y IEEE Guide for Harmonic Control and ReactiveCompensation of Static Power Converters, IEEE Standard, p.519, 1992.

y Y. Jang and M. M. Jovanovic, A comparative study of singleswitch three-phase high power factor rectifiers, IEEETrans. Ind. Appl., vol. 34, no. 6, pp. 13271334, Nov./Dec.1998.

y D. Rendusara, K. J. Slater, B. S. Lee, P. Enjeti, I. Pitel, andW. Gray,Design considerations for 12/24-pulse

autoconnected rectifiers for large VA, PWMdrive systems,in Proc., IEEE APEC 1999 Conf., pp. 903909.y D. A. Paice, Power Electronic Converter Harmonics:

Multipulse Methods for Clean Power. New York: IEEE, 1996.


12/12

y S. Choi, P. N. Enjeti, and I. J. Pitel, Polyphase

transformer arrangements with reduced kVAcapacities for harmonic current reduction in rectifiertype utility interface, IEEE Trans. Power Electron., vol.11,no. 5, pp. 680689, Sep. 1996.

y D. A. Paice, Multipulse converter system, U.S. Patent

4876634, vol. 24,Oct. 1989.y P. W. Hammond, Autotransformer, U.S. Patent

5619407, vol. 8,Apr. 1997.

y D.A. Paice, Transformers formultipulseAC/DC

converters, U.S. Patent 6101113, vol. 8, Aug. 2000.y G. R. Kamath, B. Runyan, and R. Wood, A compact

autotransformer based 12-pulse rectifier circuit, inProc. 2001 IEEE IECON, pp. 13441349.

synopsis presentation 3

Documents