Dead-ime Induced Oscillaions in Inverer-fed Inducion Moor Drives Anirudh Guha Advisor: Prof G. Narayanan Power Elecronics Group Dep of Elecrical Engineering, Indian Insiue of Science, Bangalore, India 560012 Elecrical Divisional Symposium April 29 2016
2 Inverer-fed Inducion Moor and V/f Conrol Inducion Moor Drive Inverer- fed inducion moor - for variable speed operaion. Simple conrol - Consan V/f conrol of inducion moors. Torque-Speed Characerisics Used for loads such as fans, pumps, compressors ec. These loads operae a ligh-loads a low speeds. Also during iniial esing of inverers and inducion moors, moor drive is ypically run under noload condiions using V/f conrol.
Dead-ime Induced Sub-harmonic Oscillaions in a 100-kW Inverer-fed Inducion Moor. Susained sub-harmonic oscillaions in curren a f1 = 10Hz C() Dead-ime effec T T s m R sw 1 sample V p Inverer leg S R1 S R2 SR 1 d d Normal behaviour a f1 = 30Hz SR 2 d v ROid, 0.5V dc d 0.5V dc i R v RO, ac ve v RO, err 0 V dc d Oscillaory behaviour of he drive a low and medium speeds, paricularly under no-load. Inverer dead-ime resuls in /accenuaes he oscillaory behaviour of he drive. Model drive including dead-ime effec o predic where oscillaions occur. 3
4 Modeling of Inducion Moor Drive Including he Effec of Inverer Dead-ime Dead-ime effec alers he saor volage equaions of he moor drive. Non-lineariy in saor dynamic equaions on accoun of dead-ime effec. The effec of dead-ime impacs he seady-sae operaing poin of he drive sysem as well. Small-signal model of he drive derived by linearising he non-linear sysem dynamic equaions abou a seady-sae operaing poin.
Review of Small-signal Model of Inverer fed Inducion Moor Including Inverer Dead-ime Impac of inverer dead-ime is observed in he saor R ss submarix. Deails of he 5 h order model in he poser. Sabiliy analysis performed wih he small-signal model. 5
Locus of Eigen Values of he 100kW Moor Drive Wihou and Wih Dead-Time Wihou Dead-ime Wih Dead-ime = 5 us Wihou dead-ime: eigen values wih only negaive real pars no oscillaory behaviour expeced. Wih dead-ime: oscillaions expeced beween 5 Hz and around 19 Hz explains exp. observaions Condiions: V dc = 590 V, f sw = 5 khz, V/f =0.61 pu (reduced flux) 6
7 Region of Oscillaory Behaviour of a 11kW Inducion Moor Drive on he Volage-frequency plane Roo loci wih dead-ime Eigen values ploed for d = 3us, f sw = 5kHz, V dc = 600V, V/f = 0.89 pu. Region of oscillaory behaviour obained considering differen V/f raios or flux levels. Measuremens of oscillaory behaviour in 11kW inducion moor, and in few oher moors of differen power levels carried ou Region of Oscillaory Behaviour: in collaboraion wih an indusry. Analysis Simulaion Experimen
Miigaion of Small-signal Insabiliy : Emulaion of a Virual Series Inducor Inducance Emulaion Concep Simple V/f conrol Virual Inducor Eigen values wih series inducance Proposed conrol wih inducance emulaion Inverer is conrolled such ha he erminal volage is he sum of he ideal sinusoidal volage (corresponding o he ideal modulaing signal) and he volage drop across he series inducor. 8
Conclusions and Conribuions 1. Oscillaory behaviour measured in inducion moor drives of differen power levels Collaboraion wih indusry for some of hese measuremens. 2. a) Dynamic model of inverer-fed inducion moor including effec of dead-ime. b) Seady-sae soluion of inverer-fed inducion moor including dead-ime. 3. a) Small-signal model of inverer-fed inducion moor including dead-ime. b) Sabiliy analysis o predic region of oscillaory behaviour experimenal validaion on 100kW and 11kW moors. 4. Acive damping mehod based on inducance emulaion o miigae dead-ime induced oscillaions. 5. Improved dynamic model of recifier-inverer fed inducion moor including impac of dead-ime on inverer dc inpu curren and dc link dynamics. 6. Under-compensaion and over-compensaion of dead-ime effec - Demonsraion of wo ypes of oscillaory behavior in he drive 9
Key Publicaions: [1] A. Guha and G. Narayanan, Small-signal sabiliy analysis of an open-loop inducion moor drive including he effec of inverer dead-ime, in IEEE Trans Ind. Appl., vol 52, no1, pp 242-253, 2016 [2] A. Guha and G. Narayanan, Modelling and analysis of inducion moor drive including he effec of inverer deadime, Sadhana, March 2016. [3] A. Guha and G. Narayanan, Inducance-Emulaion-Based Acive Damping of Dead-Time-Induced Oscillaions in a 100-kW Inducion Moor Drive in Proc. IEEE Transporaion and Elecrificaion Conf., ITEC India, Aug 2015. [4] A. Guha, C. Abhishek, C. Kumaresan, G. Narayanan, and R. Krishnamoorhy, Theoreical predicion and experimenal verificaion of ligh-load insabiliy in a 11-kw open-loop inducion moor drive, in Proc. NPEC 2015, Bombay, India [5] A. Guha and G. Narayanan, Impac of Dead-ime on Inverer Inpu Curren, DC-link Dynamics and Ligh-load Insabiliy in Recifier-Inverer-fed Inducion Moor Drives, acceped in IEEE SPEEDAM, Ialy 2016. [6] A. Guha, A. Tripahi, and G. Narayanan, Experimenal sudy on dead-ime induced oscillaions in a 100-kw openloop inducion moor drive, in Proc. Naional Power Elecronics Conference NPEC 2013, Kanpur, India. [7] A. Guha and G. Narayanan, An Improved Dead-Time Compensaion Scheme for Volage Source Inverers Considering he Device Swiching Transiion Times, in Proc. IEEE IICPE, 2014, Kurukshera, India [8] A. Guha, C. Abhishek, E,Panda, C. Kumaresan, G. Narayanan, and R. Krishnamoorhy, Experimenal Case Sudies on Dead-Time Induced Oscillaions and is Miigaion in 5-HP and 10-HP Inducion Moor Drives, in IEEE ICEES 2016 10