Abstract. Keywords. 1. Introduction. 2. System Description. Ajay Kumar Maurya 1, Kishore Chahar 2, Y. K. Chauhan 3

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1 International Journal of Advanced omputer Research (ISSN (print): ISSN (online): ) Volume-3 Number-1 Issue-8 March-213 Analysis on Photovoltaic Assisted Three Phase five level Unipolar PWM Inverter for Induction Motor Driven Water Pumpin System Ajay Kumar Maurya 1, Kishore hahar 2, Y. K. hauhan 3 Department Of lectrical nineerin, School of nineerin, Gautam Buddha University 1,2,3 Gr. Noida, India ajaymauryaee@mail.com 1 Abstract This paper presents the analysis of a photovoltaic bases three-phase five level voltae source inverter (VSI) supplyin induction motor driven water pump. The VSI uses a unipolar PWM technique for producin three phase 5 level voltae output and this output is used to drive three-phase induction motor drivin a pump load. Multilevel inverters are used for eneratin A voltae from several levels of D voltaes and enhance the performance of the system. The proposed system is used to reduce the filterin requirements and reduce the amplitude of all harmonics at the output of the inverter. The Power quality improves by reducin the harmonics level. The complete simulation model is simulated in MATLAB/SIMULINK and validates the theoretical considerations. Keywords Five level inverter, Induction motor drive, Photovoltaic array, Pump load, Unipolar PWM onverter. 1. Introduction Nowadays solar power is the quintessential enery source and receivin considerable attention from the researchers. Solar photovoltaic (PV) system enerates electricity with advantaes such as no pollution, no noise and many more. Solar PV is well suited to remote or arid reions. Solar water pumpin system is fast becomin an accepted means of obtainin water in remote areas where national rid connection is not viable [1]. There are numerous photovoltaic power systems ranin from 1 W to several meawatts [2]. PV cells are enerated dc power, and further feed to the power conditionin system. In order to suit the frequency and voltae level requirement of the load, a suitable switchin power inverter is used. The Major problem in power inverter is to eliminate harmonics and this aspect has been received attention 31 of researcher for many years. It is found that multilevel inverters ives satisfactory performance in hih power industrial applications [3][4]. Because multi level inverter output waveform increase in steps that s why it produced lower dv/dt stress in load side [5][6] also multi level inverter ives staircase waveforms synthesized a nearly sinusoidal voltae waveform with low harmonic distortion, thus reducin filter requirements. While the multilevel inverter requires more switches, capacitors and diodes than conventional two-level inverters, but here the advantae of multilevel inverter is that it offers the possibility of lower switchin frequency, which leads to hiher efficiency and lower electromanetic interference (MI) [7]. The Applications of multi level inverter covers wide area in industrial as well as in heavy industries, such as pumps, compressors, crushers, extruders, fans, marine propulsion, rindin mills, mine hoists, rollin mills, conveyors, blast furnace blowers, mixers, reactive power compensation, hih-voltae direct-current (HVD) transmission, hydro-pumped storae, as turbine starters, wind enery conversion, railway traction etc. [3]. This five level inverter connected to a 3-Ø induction motor. The Use of induction motor ives several advantaes as comparison to D motor. The Induction motor offers several advantaes of bein inexpensive, more robust etc. than other counterparts [1]. In this paper, the attempt has been made on analysis of multi-level inverter supplyin induction motor driven a water pump for irriation purpose. 2. System Description The omplete system is divided into three major parts a) Photovoltaic system, b) Three phase five level voltae source inverter (VSI) topoloy, c) Induction motor drive water pump. The Various components of system are described as,

2 Solar PV Refrence sinal International Journal of Advanced omputer Research (ISSN (print): ISSN (online): ) Volume-3 Number-1 Issue-8 March-213 II. Five-level inverter topoloy Five Level VSI ontrol ircuit to enerate ate sinal 3-Phase Induction Motor Outlet Water Pump Fi-1: Schematic diaram of complete system The Schematic diaram of complete system is shown in fi-1. In it solar PV dc power output is feed to three-phase five-level VSI. The Pump load is driven by induction motor, which draws power from fivelevel VSI. I. Photovoltaic system The PV cell characteristics are stronly nonlinear in nature; its most referred equivalent circuit [8] is shown in fi-2. The Related expression is iven in equation (1) [9] as follows: Inlet In multilevel inverter, a unipolar technique is proposed for eneratin five voltae levels and is shown in Fi-3. In this unipolar technique each inverter phase requires four IGBTs. The line-toneutral voltae with this power circuit has 5-levels in voltae. The load for each phase in connected throuh two filter inductor, here La1 and La2 for phase a. ach IGBT carries half of the load current [11]. [a1] Sa1 [a2] Sa2 La1 [a3] Sa3 [a4] La2 Sa4 [b1] Sb2 Sb1 [b2] Sb3 Sb4 Sc1 Sc2 Sc3 Sc4 A R a R b B R c [b3] [b4] [c1] [c2] [c3] [c4] I PV I d R sh R s Fi-2: quivalent circuit of solar PV As shown in the fi-2, I PV stands for PV shortcircuits current, I d is a diode current, R s means the series resistance of photovoltaic cells, R sh represents the photovoltaic battery parallel resistance, the internal value is less than 1 Ω.[1] The equation overnin the behavior of photovoltaic cell is expressed as, I I I e PV q V IR s AKT 1 Rsh (1) Where, I PV = Photo-enerated current (A) I= ell output current (A) I =Diode Saturation urrent (A) V=ell Output Voltae (V) R s =Series Resistor (Ω) e= lectron hare (coul) K=Boltzman onstant (j/k) T=cell temperature For simplicity PV is replaced by a dc battery in this paper. V IR s Fi-3: Five level unipolar topoloy The modulation scheme for phase a is shown in fi- 4 and fi-5[11]. The Hih frequency trianular carrier waves are compared with the reference sinal and in turn enerate the PWM pulses. In this method reference sinal is in the form of sine wave. When the reference sinal is reater or equal to the trianular carrier wave than switch Sa1 is ON and Sa2 is OFF. The modulation switchin scheme for switch Sa1 & Sa2 are shown in fi-4 and modulation scheme for switch Sa3 and Sa4 are shown in fi-5. When reference sinal is reater than or equal to trianular carrier wave switch Sa3 is ON otherwise switch Sa4 is ON. Here reference sinal frequency is 6Hz Time in seconds Fi-4: Modulation scheme for switch Sa1 & Sa2 32

3 Torque p.u 1 International Journal of Advanced omputer Research (ISSN (print): ISSN (online): ) Volume-3 Number-1 Issue-8 March Time in seconds.3 Fi-5: Modulation scheme for switch Sa3 & Sa4.2 III. Induction motor driven water pump.1 In this paper three phase induction motor is drivin a water pump system. The startin torque required by a water pump is shown Fi-6. In order to overcome the static friction torque, 1% of full-load torque is allowed at standstill as there is no land friction. When the pump fails to meet the line of torque, then torque taken by water pump is proportional to square of speed [12][13]. The speed-torque characteristic of pump load is expressed in q. (2), where quantities are expressed in p.u. [14] T=1.473ω ω+.22 (2) Speed p.u Fi-6: The water pump speed-torque characteristics 3. Simulink model of complete system The omplete simulation model based on Matlab/Simulink is shown in fi-7, which contains three major sections. First one is inverter section, second section is induction motor, and third one is pump load. A three phase squirrel cae 22V, 6Hz induction motor is used, whose parameters are iven in Table A1 of appendix. The induction motor is run by three phase five level VSI and it is used for drivin a water pump load. Discrete, s = 1e-6 s powerui [a1] [a3] [b1] [b3] [c1] [c3] pump load [a2] [a4] [b2] [b4] [c2] [c4] f(u) -K- [a1] a1 [b1] b1 [c1] c1 15 Tm Induction machine <Stator current is_a (A)> <Stator current is_b (A)> [a2] [a3] a2 a3 [b2] [b3] b2 b3 [c2] [c3] c2 c3 A B m <Stator current is_c (A)> -K- <Rotor speed (wm)> [a4] a4 [b4] b4 [c4] c4 ->RPM <lectromanetic torque Te (N*m)> <Rotor current ir_a (A)> Scope Fi-7: omplete simulation model 33

4 Phase to Neutral Voltae (V) Three phase voltae Voltae (V) Voltae (V) International Journal of Advanced omputer Research (ISSN (print): ISSN (online): ) Volume-3 Number-1 Issue-8 March Results and Discussion The Performance analysis of the system is studied usin various system quantities such as voltae enerated, torque, rotor current, stator current, Speed, water pump power V/s speed curve, THD analysis Followin investiations are carried out on the system to verify the system model. I. Analysis of five level inverter output for resistive load with and without filter For resistive load each phase is havin a resistance of 5Ω. The output waveform of three-phase five-level, 6Hz, VSI phase to phase voltae is shown in fi-8, phase to neutral voltae for phase a in fi-9, and, phase to neutral voltae for three phase is shown in fi-1 for load without filter inductor. After usin small filter inductance; L a1, L a2 for phase a, each one havin value of 1.5mH, output waveform is shown in fi-11. For phase to neutral voltae the five levels counted as:,+v/4,+v/2,+3v/4,+v as shown in fi-9 and fi- 1 [11] Fi-1: Three phase, phase to neutral voltae Fi-11: Three phase output waveform the of five level inverter with filter -1-2 II. Analysis of five level inverter output for induction motor-pump load system Fi-8: Three phase, phase to phase output waveform the of five level inverter without filter Fi-9: Phase to neutral voltae for phase a Normally levelin in multi-pulse converters are counted based on phase voltae. Here five steps as +V dc,+ V dc /2,, -V dc /2, -V dc. in phase to phase voltae are derived from dc side voltae [11]. When this 3-Ø five-level VSI is connected to 3-Ø induction motor for induction motor- pump load drive system, the output line to line voltae for three phase waveform is shown in fi-12. Fi-13 represents electromanetic torque of induction motor with permanently connected pump load. The induction motor experienced a very hih startin torque of around 47 Nm and attains steady state after some time. In steady sate, induction motor torque is around 1 Nm. Fi-14 represent s rotor current profile for phase a. Durin startin condition the rotor current is very hih and nearly about four times of steady state value. Fi-15 represents phase a stator current. The speed V/s time curve are shown in fi-16 in it speed in RPM. At steady state the speed of induction motor is 1672 RPM. Water pump power V/s speed curve is also shown in fi-17. The efficiency of induction motor for this system is nearly about 8% 34

5 Stator urrent (A) Rotor urrent (A) lectromanetic torque Te (N*m) Speed in RPM Vabc Speed in RPM 3 International Journal of Advanced omputer Research (ISSN (print): ISSN (online): ) Volume-3 Number-1 Issue-8 March Fi-12: Three phase line to line voltae waveform at induction pump load Fi-16: Speed V/s time curve Pout Fi-17: water pump power V/s speed curve III. Power quality analysis Fi-13: Induction motor electromanetic torque The FFT analysis of line-line voltae V ab has been carried out for one cycle after study state without filter inductance and with filter inductance and are shown in fi-18. In case of without filter the THD is 39.27% and after usin small filter inductance the THD reduced to 2.8% Time in seconds Fi-14: Induction motor phase a rotor current waveform Fi-18: FFT analysis of THD without filter 39.27% and 2.8% with filter Fi-15: Induction motor phase a stator current waveform 35 The Harmonic analysis of without filter inductance in phase voltae V ab as: Third harmonics present in it.9%, fourth harmonic present.5%, fifth harmonic present.1%, sixth

6 International Journal of Advanced omputer Research (ISSN (print): ISSN (online): ) Volume-3 Number-1 Issue-8 March-213 [4] B. K. Bose, Power electronics and motor drives recent proress and perspective, I Trans. Ind. lectron., Vol. 56, no. 2, pp , 29. [5] A. Nami, F. Zare, A. Ghosh and F. Blaabjer "A hybrid cascade converter topoloy with seriesconnected symmetrical and asymmetrical diodeclamped H-bride cells", I Trans. Power 5. onclusion lectron., vol. 26, no. 1, pp.51-65, 211. [6] B. Wu, Hih-Power onverters and A Drives. New York: Wiley-I Press, Mar. 26. [7]. Ozdemir, S. Ozdemir, L.M. Tolbert, Fundamental Frequency Modulated Six-Level Diode-lamped Multilevel Inverter for Three-Phase Stand-Alone Photovoltaic System Industrial lectronics, I Transactions on Vol. 56, no. 11, 29. [8]. Rodriuez, G.A.J. Amaratuna, Dynamic maximum power injection control of A photovoltaic modules usin current-mode control lectric Power Applications,I Proceedins Vol.153, no. 1,pp , 26. [9] Zhou De jia, Zhao Zhenmin, WU Libo. Analysis characteristics of photovoltaic arrays usin simulation. J T sinhua Univ (Sci & Tech), 6. Appendix 47(7): , 27. [1] X. Zhou, D. Son, Y. Ma, and D. hen, "The simulation and desin for MPPT of PV system Based on Incremental onductance Method," in Information nineerin (II), 21 WAS International onference on, Vol:2, pp , 21. [11] V. G. Aelidis and H.. Goh, "Low-distortion variable-level PWM technique," Proc. Inst. lectr. n. lectr. Power Appl., Vol. 145, no. 2, pp , [12] H.H. Anderson, W.G.rawford, Submersible, pumpin plant Proceedins of the I - Part A: Power nineerin Vol. 17, no. 32, pp , 196. [13] M. herui, M. Bourahla, A. Aissaoui, Application of The calculated PWM technique in the photovoltaic pumpin system nvironment-friendly eneries and applications (FA), pp , 212. [14] O. S. brahim, M. A. Badr, A. S. lendy and P. K. Jain "ANN-based optimal enery control of induction References motor drive in pumpin applications", I Trans. nery onvers., vol. 25, no. 3, pp , 21. harmonic present.4%, seventh harmonic present.18%, eihth harmonic present.8%, ninth harmonic present.7%, eleventh harmonic present.14% thirteenth harmonic present.6%. In this paper, the analysis on multilevel inverter fed induction motor-pump load system is studied. The proposed five-level PWM inverter produce low harmonic distortion and by usin small filter inductance the THD is reduce and power quality is enhanced. The proposed five-level inverter also has less complex control circuit in comparison to the traditional five-level inverter topoloy. The complete system is desined in MATLAB/ SIMULINK. The system performance is found to be satisfactory for induction motor-pump load system which thereby validatin the system model. Table A1: Induction motor specifications and parameters S.No. Parameter Values 1 Rotor type Squirrel-cae 2 Nominal Power Frequency 6Hz 4 Vrms 22 5 Stator Resistance.435Ω 6 Stator Inductance.2H 7 Rotor Resistance.816Ω 8 Rotor Inductance.2H 9 Mutual Inductance H 1 Inertia.89 k.m 2 11 Friction factor.5 N.m.s 12 Pole Pairs 2 [1] J.L. Davies, M. Malenret, Application of induction motor for solar water pumpin, AFRION '92 Proceedins., 3rd AFRION onference, pp , [2] B. Kroposki, R. de Blasio, Technoloies for the new millennium: Photovoltaics as a distributed resource, Proc. I Power n. Soc. Summer Meetin,Vol. 3, pp , 2. [3] F. Khoucha, M.S. Laoun, A. Kheloui, Benbouzid, M.. H.; A omparison of Symmetrical and Asymmetrical Three-Phase H-Bride Multilevel Inverter for DT Induction Motor Drives I Transactions on nery onversion, Vol.26, no. 1, pp.64-72, 211. Ajay Kumar Maurya was born in He received the B. Tech deree in electrical enineerin from U.P. Tech. University Lucknow, India. He is currently workin towards the M.Tech deree in power system at Gautam Buddha University, Gr. Noida, India. His research interests include active power filter, solar power system, multilevel inverter. 36