Inverter fault Analysis in Permanent Magnet Synchronous Motor using Matlab & Simulink

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2 Invrtr fault Analysis in Prmannt Magnt Synchronous Motor using Matlab & Simulink 1 Shashank Gupta, 2 Ashish Srivastava, 3 Dr. Anurag Tripathi 1 Sr. Lcturr, MPEC, Kanpur, 2 Sr. Lcturr, MPEC, Kanpur, 3 Associat Profssor, IET, Lucknow Abstract Th automation is highly xpandd in industrial procsss for a varity of applications, rliability, survivability, continuous opration and othr faultrlatd issus ar bcoming major concrns in th dvlopmnt of advancd. AC machin driv systms.[1] thr is a nd to analys th faults of prmannt magnt synchronous motor. In this papr I am trying to analys th prformanc of synchronous motor undr various invrtr faults. Thr ar many faults but in this papr I am daling with only singl phas opn circuit, singl, doubl & thr phas short circuit. Now a days synchronous motor is gaining importanc hnc thir analysis is a ncssity for th industrial application. 1. Introduction Prmannt magnt synchronous motors (PMSMs) hav bn widly usd in many industrial applications. Du to thir compactnss and high torqu dnsity, th PMSMs ar particularly usd in high-prformanc driv systms such as th submarin propulsion. Th prmannt magnt synchronous motor liminats th us of slip rings for fild xcitation, rsulting in low maintnanc and low losss in th rotor. Th PMSMs hav th high fficincy and ar appropriat for high prformanc driv systms such as CNC machins, robotic and automatic production systms in th industry. Modlling and simulation is usually usd in dsigning PM drivs compard to building systm prototyps bcaus of th cost. Having slctd all componnts, th simulation procss can start to calculat stady stat and dynamic prformanc and losss that would hav bn obtaind if th driv wr actually constructd. This practic rducs tim, cost of building prototyps and nsurs that rquirmnts ar achivd. In works availabl until now idal componnts hav bn assumd in th invrtr fding th motor and simulations hav bn carrid out. In this work, th simulation of a PM motor driv systm will b dvlopd using Simulink. Th simulation circuit will includ all ralistic componnts of th driv systm. A comparativ study associatd with SPWM invrtr fd PMSM undr halthy and convrtr fault conditions will b mad.. 2. Pmsm Driv Simulink Modling A prmannt magnt synchronous motor is fd from a variabl frquncy voltag sourc invrtr for control of spd and xcluding th nd of xtrnal starting modul. For starting prmannt magnt synchronous motor without xtrnal starting modul thy ar supplid through an invrtr varying its AC output frquncy from zro to ratd valu. Th voltag sourc invrtr rcivs DC voltag at its input sid and convrts this DC input to variabl frquncy AC output. Thr ar following thr moduls in th Simulink modlling of prmannt magnt synchronous motor driv. Thy ar as follows: Gat Puls Gnrator Modul Invrtr Modul Motor Modul 2.1 Gat Puls Gnrator Modul In Gat puls gnrator modul Sin Puls Width Modulation tchniqu is usd for gnration of gat pulss for th switching of six invrtr switchs. This is don by comparing thr Sin pulss with a triangular wav. Figur 1 Puls Width Modulation Switching Logic 1985

3 Whr Vtri is common triangular wav which is compard with thr control Sin pulss having a amplitud of m (m 1) and a rlativ phas diffrnc of 120 dgr with ach othr. Whn Vcontrol is highr than Vtri in amplitud uppr switchs in th Invrtr Modul switchd ON and output is Vdc/2 whil for highr valu of Vtri lowr switchs ar switchd ON and output is Vdc/2. Figur 4 Multiplxr block Th frquncy and amplitud signal gos into 3 Sin puls gnrator blocks. Th output of ths blocks ar thr Sin pulss with rlativ phas diffrnc of 120 dgr with ach othr. Figur 2 Phas A output Voltag wavform Th frquncy input to th sin puls gnrator is providd by a st of blocks which gnrats rquird sin wav frquncy for th gnration of gat pulss. Th block shown blow gnrats frquncy signal to b fd to th sin puls gnrator according to th rfrnc spd N providd by th constant block. Figur 5 Sin Wav Gnration Modul Now gat pulss ar gnratd by comparison of thr sin wavs (120 dgr displacd with ach othr) with triangular wav. Two gat pulss ar gnratd for ach phas namly (G1, G2), (G3, G3), (G5, G6). Figur 3 Frquncy Gnration Block wt = (2*pi*f)*t Th modul shown blow uss a multiplxr it rcivs two signal on is wt and scond is m dtrmining th amplitud of Sin puls. Aftr multiplxing th output is a row vctor having two signals [u1 u2]. Whr u1 = wt and u2 = m. 1986

4 Figur 6 Comparison of Sin and Triangular wav for Gat Puls Gnration Th complt Gat Puls gnrator modul by comprising th abov dscribd sub moduls is shown blow. It taks rfrnc spd signal as its input and gnrats six gat pulss for switching six switchs of thr phas Sin PWM invrtr. Figur 8 Complt Gat Puls Gnrator with fault Modul Th intrnal viw of Fault Modul is shown in figur blow. This fault modul blocks th gat pulss of thos switchs in which w would lik to introduc fault. Hr In1, In2, In3, In3, In5, In6 ar six gat puls inputs G1, G2, G3, G3, G5, G6 and s1, s2, s3, s3, s5, s6 ar post fault gat signals ithr zro or on. Figur 7 Complt Gat Puls Gnrator without fault Modul Now in ordr to introduc faults in th invrtr modul w hav modifid th abov shown gat puls gnrator by introducing a fault modul btwn th comparator output and go to block providing signal routing to th invrtr switchs. Figur 9 Insid Viw of Fault Modul. 2.2 Invrtr Modul 1987

5 Th six gat pulss gnratd from Gat Puls Gnrator modul ar supplid to a thr phas invrtr. This invrtr modulats th input DC voltag to variabl frquncy AC output according to th puls width modulation tchniqu. Figur 12 Puls Width Modulatd Invrtr fd PMSM Now this prmannt magnt synchronous motor is supplid from thr phas Sin Puls Width Modulatd Invrtr as shown in th figur abov. Figur 10 Invrtr Modul Th pak fundamntal phas voltag output from th abov dscribd SPWM invrtr will b: V ao = m*(vdc/2) Whr m is amplitud of Sin wav (m 1) kping amplitud of triangular wav at Motor Modul Th Prmannt Magnt Synchronous Machin block oprats in ithr gnrator or motor mod. Th mod of opration is dictatd by th sign of th mchanical torqu T (positiv for motor mod, ngativ for gnrator mod). Th sinusoidal modl assums that th flux stablishd by th prmannt magnts in th stator is sinusoidal, which implis that th lctromotiv forcs ar sinusoidal. 3. SIMULATION RESULTS AND DISSUSSION Figur 13 PMSM Stator Currnt undr halthy condition Figur 14 Elctromagntic Torqu during halthy condition Figur 11 Motor Modul Figur 15 Motor Spd during halthy condition Simulation of invrtr fd PMSM driv is carrid out in thr conditions. 1988

6 In first condition driv is mad to run undr normal condition without any fault. In scond condition to introduc singl phas opn circuit fault in phas a gat signals G1, G2 in post fault conditions ar mad 0. In third condition to introduc singl phas short circuit fault gat signal G1 and G2 of IGBT of phas lg a is mad 1 and 0 rspctivly during post fault priod. Aftr collction of simulation rsults of PMSM driv undr halthy conditions and undr opn phas fault and singl switch short circuit fault condition, analytical discussions ar mad by comparativ study of prmannt magnt synchronous motor rspons undr faulty and halthy conditions rsults ar prsntd. Figur 17 d-q axis Currnt during opn phas fault Figur 18 Elctromagntic Torqu during opn phas fault 3.1 SIMULATION RESULTS UNDER SINGLE PHASE OPEN FAULT Th singl-phas opn circuit may b causd by switch-on failur of both transistors of a sam lg in invrtr, an lctrical failur in on of th invrtr phas lgs, or a ruptur btwn on phas winding trminal and priphry supply. In this cas, th motor in fact is opratd by th rst 2 phass, bcaus no currnt flows in th fault phas winding. W ar using gat signal for control of th IGBT of invrtr. To introduc singl phas opn circuit fault at phas a, G1 and G2 gat signals during post fault conditions ar mad 0. Th simulation rsults for th singl phas opn circuit fault ar displayd as follows: Figur 19 Motor Spd during opn phas fault Figur 4.7 shows th gat signals G1 and G2, as th fault occurs th gat signals G1 and G2 ar 0, and th IGBT 1 and IGBT 2 ar turnd off. Th phas a is opn circuitd and dos not snd any currnt to th motor. Th phas b and c is connctd and supply currnt to th motor. Th Figur 4.8 shows th stator currnt aftr opn phas fault, aftr th fault th phas a currnt is zro bcaus th motor trminal of phas a is opn. It can b sn th currnts bcom 2 phass with 180 o lctrical position diffrnc aftr fault happns. In Figur 4.9, although th man valus of th d and q-axis currnts ar not varying too much, but th grat puls of d-axis currnt is a potntial dangr to irrvrsibly dmagntiz th PM. On th othr hand, in Fig.4.10 and 4.11, th post-fault man lctromagntic torqu is almost zro and hnc cannot maintain th pr-fault spd [6]. Figur 16 Stator Currnt during opn phas fault 3.2 Simulation Rsults Undr Singl Phas Short Circuit Fault A transistor cannot switch off, which rsults th complmntary on to b switchd off by a transistor protction circuit. Th othr potntial rason is a phas trminal ruptur and ground of phas trminal. Hr in ordr to introduc singl phas short circuit fault gat signals G1 and G2 ar mad 1 and 0 rspctivly during post fault condition. 1989

7 motor, th avrag of gnratd torqu as shown in Figur 4.15 is zro. Du to th positiv and ngativ grat torqu puls th motor spd falls. Compard with th opn phas post-fault rsults, th singl-short circuit is th most dangrous fault. Th hug short circuit currnt not only is possibl to lad to irrvrsibly dmagntizing of PM, but also could burn th armatur coil [3],[6]. 4. Conclusion Figur 20 Stator Currnt during singl phas short circuit fault This projct analyzd th potntial faults of PMSM in singl invrtr lg. According to th logic analysis rsults, a sris of dynamic simulations for ths faults ar stablishd in Simulink@ MATLAB. Espcially, th constructions of ky moduls hav bn shown in th projct. Finally, according to th proposd simulation modls, th two faults including singlphas opn circuit, singl-phas short circuits ar implmntd succssfully. Th validity of ths simulation mthods has bn xplaind and analyzd dpnding on th rsult wavforms. Figur 21 d-q axis Currnt during singl phas short circuit fault Compard with th opn phas post-fault rsults, th singl-short circuit is th most dangrous fault. Singl phas short circuit givs th highst transint pak currnt. Th opn-circuit fault rprsnts a rlativly bginning oprating condition, particularly if th machin s back-mf is low (i.., low) and th post-fault control stratgy is to immdiatly rmov th switch gat pulss. Figur 22 Elctromagntic Torqu during singl phas short circuit fault Tabl 1 comparison of rsults paramtr Motor in halthy conditi on Op n phas fault Sing l phas short circu it Two phas short circu it Thr phas short circu it Figur 23 Motor Spd during singl phas short circuit fault In figur 4.13, th currnt of fault phas gts dominantly positiv aftr sc, and th polaritis of othr 2-phas currnts ar ngativ. This accords with th wy connction of 3-phas windings, and th sum of 3-phas currnts always is zro. Du to th dominant dc componnt, th fault phas currnt is limitd by th phas rsistanc. Dspit th high currnt is applid to Pak Stator currnt (amp) Ia Ib Ic to

8 Pak Elctromagnt ic torqu(n-m) to Phas Opn Circuit Fault IEEE Transactions On Powr Elctronics, Vol. 17, Spt [9] S. Angayarkanni, A. Snthilnathan and R. Ilango, Svpwm Controlld Prmannt Magnt Synchronous Motor (IJITR) Intrnational Journal Of Innovativ Tchnology And Rsarch,vol no-1, Dc-Jan Pak spd(rpm) 1545 to to to 675 [10] T.J.E.Millr, Brushlss prmannt magnt and rluctanc motr drivs,clarndon prss,1989 [11] R.Krishnan, Prmannt Magnt Synchronous and Brushlss DC Motor Driv, CRC Prss,1988. [12] M.H. Rashid, A Powr Elctronics Handbook Acadmic Prss Dirct axis pak currnt(amp) to [13] Nd Mohan, Tor M. Undland, William P. Robbins, Powr Elctronics: Convrtrs, Applications, and Dsign. John Wily & Sons Inc,1989. [14] Mustafa Aktaş, A Novl Mthod For InvrtrFaults DtctionAnd Diagnosis In Pmsm Drivs Of Hvs Basd On Discrt Wavlt Transform Advancs In Elctrical And Computr Enginring Volum 12, Nov 4, Quadratur axis pak currnt(amp) 3.45 to Rfrncs [1] AWADALLAH M.A., MORCOS M.M., GOPALAKRISHNAN S., NEHL T.W.: Dtction of stator short circuits in VSI-fd brushlss DC motors using wavlt transform, IEEE Trans., [2] Tck-sng Low, Mohannd.A. Jabbar, Spd Control of Prmannt Magnt Synchronous Motor Driv Using an Invrtr, IEEE trans. Industry application Vol.-26 Jan/Fb [3] Rammohan Rao Errablli and Ptr Mutschlr, Fault-Tolrant Voltag Sourc Invrtr for Prmannt Magnt Drivs IEEE Trans. on powr lctronics, vol. 27, no. 2, Fb [4] Ptr Thlin, Short circuit fault conditions of a burid PMSM invstigatd with FEM Prsntd at NORPIE/2002, Stockholm, Swdn, August [5] Quntao An, Guanglin Wang and Li Sun, A Fault- Tolrant Opration Mthod of PMSM Fd by Cascadd Two-Lvl Invrtrs IEEE 7th Intrnational Powr Elctronics and Motion Control Confrnc - ECCE Asia, Jun 2-5, [6] Pragasan Pillay and R.krishnan, Modling of Prmannt Magnt Motor Drivs IEEE Trans on industrial lctronics, vol.35, no.4, Nov [7] Tao Sun, Suk-H L and Jung-Pyo Hong, Faults Analysis and Simulation for Intrior Prmannt Magnt Synchronous Motor Using Simulink@MATLAB Procding Of Intrnational Confrnc On Elctrical Machins And Systms 2007, Oct. 8-11, [8] Brian A.Wlchko, Thomas M.Jahns and Silva Hiti, IPM Synchronous Machin Driv Rspons to a Singl- 1991