FPGA BASED HARDWARE IMPLEMENTATION OF WTHD MINIMISATION IN ASYMMETRIC MULTILEVEL INVERTER USING BIOGEOGRAPHICAL BASED OPTIMISATION

Harmonic Elimination and THD Minimisation in asymmetric cascaded multilevel inverter involves complex nonlinear non convex trigonometric transcendental equations which has several solutions.Among the various topologies of cascaded multilevel inverter asymmetric cascaded multilevel inverter has the advantage of reduced switch count when compared to traditional symmetric multilevel inverter topology. In this paper FPGA based hardware implementation is carried for a 13 level inverter by using offline computation of switching angle with weighted total harmonic distortion (WTHD) as the objective function. WTHD optimisation offers the blend of eliminating the specific lower order harmonics as in SHE-PWM and minimisation of THD as in OMTHD. The simulation and experimental results were presented for 7 level symmetric and 13 level asymmetric inverter. The experimental waveforms were analysed for THD and lower order harmonics using fluke power analyser and comparison of WTHD with SHE-PWM and OMTHD are presented .The results indicates that in a 13 level inverter the WTHD based optimisation yields reduced THD of 5.35% in simulation and 5.9% experimentally.It also eliminates all the specified 5th ,7th ,11th ,13th and 17th lower order harmonics.

Keywords:

WTHD, BBO SHE- PWM, OMTHD,

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R.Kavitha completed her B.E from
Bharathiar University, India and M.E
Degree from Anna University in 2001 and
2004 respectively. She has 11 years of
teaching Experience and pursuing Ph.D. in
Anna Univerity, Chennai. She is now working
Professor in Kumaraguru college of
Technology, India. She is a life member of
ISTE. Her research interests are Multilevel
inverters and Optimisation Techniques.
Dr.Rani Thottungal obtained her B.E and
M.E degree from Andhra University,India
and her Ph.D degree from Bharathiar
university,India. She has 23 years of
teaching Experience. She is currently
working as Professor in Kumaraguru
college of Technology,India. She is a life
member member of ISTE and IE. Her
research interests includes power system and FACTS.