11-Level Multilevel Inverter with Reduced Number of Switches using Level Shift Modulation

Transcription

1 Aailable online at: Special Issue fro 2 nd National onference on oputin, lectrical, lectronics and Sustainable nery Systes, 6 th 7 th July 2017, Rajahundry, India 11Leel Multileel Inerter with Reduced Nuber of Switches R.Satyaleelaara Prasanth 1 M.John Sreeniasa Rao 2 1PG Scholar, Departent of, Godaari Institute of nineerin and Technoloy, Rajahundry, Andhra Pradesh, India. 2Asssitant Professor, Departent of, Godaari Institute of nineerin and Technoloy, Rajahundry, Andhra Pradesh, India. To ite this Article R.Satyaleelaara Prasanth and M.John Sreeniasa Rao, 11Leel Multileel Inerter with Reduced Nuber of Switches, International Journal for Modern Trends in Science and Technoloy, Vol. 03, Special Issue 04, July 2017, pp ABSTRAT The ultileel conerter to achiee hiher power is to use a series of power seiconductor switches with seeral lower oltae dc sources to perfor the power conersion by synthesizin a staircase oltae waefor. Batteries can be used as the ultiple dc oltae sources. This paper focus on phase shifted and leel shifted pw based cascaded ultileel inerter fed drie. It offer seeral adantaes copared to the conentional 3phase bride inerter in ters of lower d/dt stresses, lower electroanetic interference, saller ratin and hih efficiency. The proposed ethod has been desined an thirteen leel cascaded ultileel inerter by usin phase shifted and leel shifted pulse width odulation technique and copare the Total haronic distortion. The selected pattern has been exposed to ie superior perforance in total haronics distortion. Siulation and experiental results confir the feasibility of proposed ethod. Keywords Multileel inerter, ascaded Hbrides, Batteries, PWM Technique, THD opyriht 2017 International Journal for Modern Trends in Science and Technoloy All rihts resered. I. INTRODUTION Power electronic deices play a ajor role in the conersion and control of electric power, especially to extract power fro renewable enery sources like photooltaic array and wind enery [1]. onersion of D to A power can be done with the help of inerters (sinle phase or three phases). onentional bipolar inerters produce alternatin staircase waefors with hiher haronics. Thus, the ultileel inerters (MLI) were deeloped [2]. This paper proides a new three phase confiuration to produce the IIleel output with less total haronic distortion (THD) in its output oltae. IPD, APD, O and VF PWM techniques were used to produce switchin pulses[3]. The cascaded Hbride (HB) confiuration has lesser nuber of coponents as copared to the conentional diode claped or capacitor claped inerters [4]. It contains sinle phase inerters connected in series with separate D sources that can be deried fro renewable enery sources like solar PV cell, bio fuel cell or wind turbine [5]. ach sinle phase inerter produces two D oltae leels. Brides with separate D sources are cascaded to each other for ore D leels. The switches operate at fundaental frequency of 50Hz. The diode claped MLI has 20 switches, 90 diodes and 10 ain Dbus capacitors per phase to produce an 11 leel staircase as the output oltae. The capacitor claped MLI uses 20 switches, 45 clapin capacitors and 10 ain Dbus capacitors per phase whereas the cascaded Hbride inerter uses only 24 switches per phase to produce the sae output [67]. This 53 International Journal for Modern Trends in Science and Technoloy, Volue 3, Special Issue 4, July 2017

2 R.Satyaleelaara Prasanth and M.John Sreeniasa Rao : 11Leel Multileel Inerter with Reduced Nuber of Switches paper describes a sinle phase inerter confiuration with eiht switches and three D sources. A three phase ultileel inerter is obtained by interconnectin three sinle phase inerters to a star connected pure resistie load with a coon earth point. Therefore, this circuit offers lesser ate control circuitry, lesser cost, lesser heatin, ore ease of installation and lesser electroanetic interference. Table.I shows the coparison of the nuber of coponents between different topoloies. The perforance of the inerter usin IPD, APD, O and VF PWM ethods is shown [8]. A passie series L filter is desined to produce a sine wae fro the staircase inerter output. The purpose of the output L filter is attenuatin oltae ripples due to the inerter switchin [9]. II. MULTILVL INVRTR Iportance of ultileel inerter A power inerter, or inerter, is an electronic deice or circuitry that chanes direct current (D) to alternatin current (A). The input oltae, output oltae and frequency, and oerall power handlin depend on the desin of the specific deice or circuitry. The iportance of ultileel inerters has been increased since last few decades. These new types of inerters are suitable for hih oltae and hih power application due to their ability to synthesize waefors with better haronic spectru and with less Total Haronic Distortion (THD). Nuerous topoloies hae been introduced and widely studied for utility of nonconentional sources and also for drie Main feature of MultiLeel Inerter (MLI) 1. Ability to reduce the oltae stress on each power deice due to the utilization of ultiple leels on the D bus. 2. Iportant when a hih D side oltae is iposed by an application (e.. traction systes). 3. en at low switchin frequencies, saller distortion in the ultileel inerter A side waefor can be achieed (with stepped odulation technique). Adantaes of MultiLeel Inerter (MLI) A ultileel conerter has seeral adantaes oer a conentional twoleel conerter that uses hih switchin frequency pulse width odulation (PWM). The attractie features of a ultileel conerter can be briefly suarized as follows. 1. Staircase waefor quality: Multileel conerters not only can enerate the output oltaes with ery low distortion, but also can reduce the d/dt stresses; therefore lectro Manetic opatibility (M) probles can be reduced. 2. oonmode (M) oltae: Multileel conerters produce saller M oltae; therefore, the stress in the bearins of a otor connected to a ultileel otor drie 3. Input current: Multileel conerters can draw input current with low distortion. 4. Switchin frequency: Multileel conerters can operate at both fundaental switchin frequency and hih switchin frequency PWM. It should be noted that lower switchin frequency usually eans lower switchin loss and hiher efficiency. Unfortunately, the ultileel conerters do hae soe disadantaes. One particular disadantae is the reater nuber of power seiconductor switches needed. Althouh lower oltae rated switches can be utilized in a ultileel conerter, each switch requires a related ate drie circuit [40]. This ay cause the oerall syste to be ore expensie and coplex. Plentiful ultileel conerter topoloies hae been proposed durin the last two decades. onteporary research has enaed noel conerter topoloies and unique odulation schees. In recent years, new industrial applications for ediu and hih oltae otors (which ay require oltaes in eawatts ranes) applied these inerters which can be used as an alternatie to the power of a ultileel conerter for hih and ediu renewable enery sources. The use of ultileel conerters has been started since 1975, which is in fact the deelopent of the twoleel 54 International Journal for Modern Trends in Science and Technoloy, Volue 3, Special Issue 4, July 2017

3 R.Satyaleelaara Prasanth and M.John Sreeniasa Rao : 11Leel Multileel Inerter with Reduced Nuber of Switches conerters. Purpose of the use of ultileel conerters, access to a hih power is the key to a series of seiconductor strenth and low D oltae sources for enery conersion based on eleents such as capacitors, batteries and renewable enery sources is ipleented. Usin the appropriate switchin and considerin seeral sources of input D conerters, hih oltae can be obtained in a ultileel conerter output. Multileel conerters hae adantaes and disadantaes copared to two leel conerters considerin switchin frequency and Pulse Width Modulation (PWM) can include. 1 Quality of the A output waefor: a ultileel conerter cannot only produce a oltae output with extreely low distortion, also capable of decreased stress d /dt. So the proble of electroanetic interference (MI) can be reduced. 2 Less oon Mode oltae (M): less M oltae ultileel conerters and therefore less stress on the otor bearins as well as seiconductor coponents connected to a ultileel inerter will be reduced. 3 The input source: the use of ultileel conerters can already hain low distortion input sources, probles related to power quality in distribution systes to oercoe. 4 Switchin frequency: ultileel conerters can be both priary and hih switchin frequency to be used. Lower switchin frequency usually eans hiher efficiency as well. The disadantaes of ultileel conerters can also be suarized as follows: 1 To be expensie due to the hih nuber of switchin eleents (which cannot be econoically affordable.) 2 Desin coplexity due to the lack of sufficient knowlede (creates probles) 3 Different techniques for controllin conerters, ultileel proided. xaple can be pulse width odulation sine, eliinatin the haronic selectie odulation ector space entioned. Most iportant applications of inerters ultileel can to drie otors, ediu oltae, transission systes A flexible and renewable enery sources are connected to the rid. In this section, the adantaes and disadantaes of ultileel conerters, kind of acties switch usae, how to chare and dischare the closin of diodes and capacitors of the conerter structure and especially for the inerter connected to the rid will be reiewed III. MODULATION SHMS To control the frequency and haronics of the output oltae of the inerter, we ust select the ost appropriate PWM technique. The sinusoidal PWM (SPWM) ethod has been applied to the power switches, in which a reference sinusoidal wae of fundaental frequency is copared to hih frequency carrier wae(s). The leel, frequency or aplitude of the ultiple carrier sinals are aried based on the PWM technique. The odulation indices are kept sae in all the ethods for coparison. Aplitude odulation index is the ratio of the aplitude of the reference sine wae to the aplitude of the carrier waes. Frequency odulation index, is defed as the ratio of the frequency of carrier wae to the frequency of the odulatin wae. The PWM techniques in this paper are InPhase Disposition (lpd) type leel shift pulse width odulation (LSPWM), AntiPhase Disposition (APD) PWM, arrier Oerlap (O) PWM and Variable Frequency (VF) PWM. The aplitude odulation index rna is aintained at 0.9 and the frequency odulation index r at 200. The RMS alue of the fundaental coponent of the output oltae and the total haronic distortion (THD) are obsered by usin siulation results. In all the PWM techniques, 'N' nuber of carrier sinals are used to obtain 2N 1 oltae leels. In this paper, control technique of phase shifted (PSPWM) and leel shifted (LSPWM) pulse width odulation stratey is eployed. The two pw techniques are, 3.1 Phase Shifted PWM (PSPWM) Fi. 2 Phase Shifted arrier PWM In psc pw all the trianular carriers hae the sae frequency and sae peakpeak aplitude.but there is a phase shift between any two adjacent carrier waes.for Voltae leels (1) carrier sinals are required and they are phase shifted with an anle of θ=(360 /1).The ate sinals are enerated with proper coparison of carrier wae and odulatin sinal. 3.2 Leel shifted PWM (LSPWM For carriers sinals, the tie alues of each carrier waes are set to [0 1/600 1/300] while the outputs alues are set accordin to the disposition of carrier 55 International Journal for Modern Trends in Science and Technoloy, Volue 3, Special Issue 4, July 2017

4 a k a k a k R.Satyaleelaara Prasanth and M.John Sreeniasa Rao : 11Leel Multileel Inerter with Reduced Nuber of Switches waes. After coparin, the output sinals of coparator are transitted to the IGBT. This technique is diided into 3 types, In Phase disposition (IPD) IV. PROPOSD IRUIT The proposed inerter confiuration has 10 switches and two D sources per phase as shown in Fi.l. The series cobination aon the two D sources V dc, 2V dc and 2V dc can be used to produce eleen D leels at the inerter output in a sinle cycle. Fi.2 proides the siulation circuit of the proposed sinle phase circuit in MA TLAB. In each ode, four of the switches operate siultaneously. Fi.3 in phase disposition Discrete, s = 5e005 Vo All the carrier sinals are in phase. Discrete, s = 5e005 G6 PV1 PV Syste6 PV2 PV Syste4 s1 Display2 sp To Workspace sn Phase opposition disposition (POD) Staircase PWM T6 G4 T4 G5 T5 PV3 PV Syste5 PV4 PV Syste7 G7 s2 T7 Display1 sn i sp Subsyste PV5 PV Syste1 PV6 PV Syste3 G3 Display5 G1 T1 T3 PV7 PV Syste2 s3 G2 Voltae Measureent Scope Fi.4 phase opposition disposition All the carriers aboe zero reference are in phase but in opposition with those are below zero reference. Alternate phase opposition disposition (APOD) T2 Fi 1: Proposed Siulation ircuit V. SIMULATION RSULTS In this section, the proposed control structure is siulated in MATLAB SIMULINK enironent. A resistie load is connected by the hbride. Fi.5 Alternate phase opposition disposition The odulatin sinal of each phase is displaced fro each other by 120. All the carrier sinals hae sae frequency Fc and aplitude Ac while the odulatin sinal has a frequency of f and aplitude of A. The fc should be in inteer the ultiples of f with threeties. This is required for all the odulatin sinal of all the three phases see the sae carriers, as they are 120 apart. The carrier waes and the odulatin sinals are copared and the output of the coparator defines the output in the positie half cycle the coparator output will hae the alue hih, if the aplitude of the odulatin sinal is reater than that of the carrier wae and zero otherwise. Siilarly for the neatie half cycle, if the odulatin sinal is lower than the carrier wae the output of the coparator is hih and zero otherwise. Fi no: 5.1 siulink output of the inphase disposition Fi no: 5.2 siulink result for the anti phase disposition. 56 International Journal for Modern Trends in Science and Technoloy, Volue 3, Special Issue 4, July 2017

5 Ma (% of Fundaental) R.Satyaleelaara Prasanth and M.John Sreeniasa Rao : 11Leel Multileel Inerter with Reduced Nuber of Switches fi no: 5.3 siulink result for the carrier oerlap Leel Shifted PWM (Pulse Generator) Fi no: 5.4 Sinusoidal output oltae wae for for three phase 11 leel inerter usin VFPWM technique with series L filter. Load Voltae 200 Selected sinal: 10 cycles. FFT window (in red): 1 cycles Tie (s) 4 Fundaental (50Hz) = 215.9, THD= 4.56% Fi no 5.5 FFT Analysis of the haronic spectru for VF PWM technique (with L filter) Frequency (Hz) THD Analysis for Load Voltae (4.56%) sp sn Scope VI. ONLUSION Repeatin Sequence 5 onstant 3 onstant1 1 onstant2 AND s2 s3 = 0.5 s1 Fi: Pulse enerator for the proposed circuit Scope1 Three phase eleen leel inerter topoloy with less nuber of switches is proposed and siulated. Various PWM ethods are analyzed and copared. Fro the siulation results, it was found that VFPWM proides iniu THD of 12.51% in the inerter output oltae. This will be the best PWM technique for inerter switchin because sall inductance can be used in the L filter placed in series to the inerter output to produce a rectified A sine wae of low THD of 1.77%. Future Scope: The control technique offers ultileel power conerters can be further siplified and eneralized to different leels and other class of 57 International Journal for Modern Trends in Science and Technoloy, Volue 3, Special Issue 4, July 2017

6 R.Satyaleelaara Prasanth and M.John Sreeniasa Rao : 11Leel Multileel Inerter with Reduced Nuber of Switches power conerters and inerters. The leels of ultileel confiuration can be increased and further iproeents in ters of perforance and power quality issues can be broadly studied and could be ipleented with hard ware circuits. Motion ontrol onference, 1720 May IPM, I 6th International, Pp RFRNS [1] H. Fujita, and H. Akai, "A practical approach to haronic copensation inpower systesseries connection of passie and actie filters," in Industry Applications Society Annual Meetin, 1990., onference Record of the 1990 I, 1990, pp ol2. [2] Rodriuez J., Lai J.S., Pen F.Z.'Multileel inerters: A surey of topoloies, controls, and applications'. I Trans. Ind. lectron., o1.49, no. 4, pp , Au [3] Malinowski, M.;G opakuar, K.;R odriuez, J.; Perez, M.A;, "A Surey on ascaded Multileel Inerters," Industrial lectronics, I Transactions on, o1.57, no.7, pp , July [4] Balauruan c.r., Natarajan S.P., Vidhya V.'A New Modified Hybrid HBride Multileel Inerter usin less Nuber of Switches'. International onference on oputation of Power, nery, Inforation and ounication (IPI), 2013, pp 16. [5] Mohaed AS, Noran Mariun, Nasri Sulaian, MArnran M. Radzi :"A New ascaded Multileel Inerter Topoloy with Miniu Nuber of onductin Switches," I Innoatie Sart Grid TechnoloiesAsia (ISGT ASIA) [6] Khofoi S., Praisuwanna N., Tolbert L.M. :"A Hybrid ascaded Multileel Inerter Application for Renewable nery Resources Includin a Reconfiuration Technique," lectrical nineerin and oputer Science, The Uniersity of Tennessee, USA [7] Salodkar P., Sandeep N., Kulkarni P.S., Ajaykuar R.Y.:'A oparison of SeenLeel Inerter Topoloies for Multileel DA Power onersion'. I International onference on Power lectronics, Dries and nery Systes (PDS), [8] Beii L.M.A., Azli N.A., Khosrai F., Najafi., Kaybhosrai A: 'A New Multileel Inerter Topoloy with less Power Switches', International onference on Power and nery, 2012, I, 25 Deceber [9] Vadhiraj S., Narayana Sway K., Diakar B.P. ;, "Generic SPWM Technique for Multileel Inerter," lectrical and lectronics Dept, RVA Institute of Technoloy and Manaeent, Banalore, India. [10] Hyosun Ki, SeunKi Sui, "Analysis on Output L Filters for PWM Inerters", Power lectronics and 58 International Journal for Modern Trends in Science and Technoloy, Volue 3, Special Issue 4, July 2017