Multilevel Inverters (Copyrighted Material) Prasad Enjeti, Ph.D.

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1 Multilevel Inverters (Copyrighted Material) Prasad Enjeti, Ph.D. Associate Dean for Undergraduate Programs TI-Professor of Electrical & Computer Engineering Power Electronics & Power Quality Laboratory Texas A&M University, College Station, TX 77843, USA

2 The Texas Workforce Commission is projecting a 19 percent growth in engineering jobs in the next 12 years. This equates to more than 43,000 jobs. This projection mirrors a recent call by the Presidents Council of Advisors on STEM for the nation to increase the number of STEM graduates to one million in the next 10 years. More than 10,000 students applied to the Look College in 2012 for the 1,600 slots TAMU enrollment for Fall 2012 was 11,281 total students (8,397 undergraduate; 1,375 masters; 1,509 doctoral) Anticipated annual growth of: 6.5% UG ; 15% M.S.

3 Module Outline Multilevel Inverters (Copyrighted Material) Basic principle & types of multilevel inverters Pulse width modulation techniques Modular multilevel inverters Applications: a) Adjustable speed ac drives, b) Solar/Wind energy systems, c) Utility scale HVDC light systems, d) Fuel cell and battery energy storage systems Prasad Enjeti, Ph.D. Associate Dean for Undergraduate Programs TI-Professor of Electrical & Computer Engineering Power Electronics & Power Quality Laboratory Texas A&M University, College Station, TX 77843, USA

4 ECEN 613 Rectifier and Inverter Circuits Fall 2013 Professor: Course Notes: Textbook: Dr. Prasad Enjeti Rm. 128, ZEC, Tel: , TAMU Supplementary Course Notes Power Electronics Converters, Applications & Design (Third edition), by: Ned Mohan et al., John Wiley & Sons. (Available online for free: ) COURSE WEBPAGE: Students login: use your TAMU NEO account username & password.

5 ELEN 613 Rectifier and Inverter Circuits - Fall 2013

6 Multilevel Inverters 3-level half-bridge Reference: L. Helle, S.M. Nielsen, P. Enjeti, Generalized discontinuous dc-link balancing modulation strategy for 3-level inverters, IEEE PCC 2002, pp ECEN 613 Rectifiers & Inverters Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University 6

7 Multilevel Inverters - NPC 3-level half-bridge neutral point clamped (NPC) Gating signals Output voltage waveforms Reference: A. Nabae, I. Takahashi, H. Akagi, A new neutral-point clamped PWM inverter, IEEE Transactions on Industry Applications, Sep/Oct 1981, pp ECEN 613 Rectifiers & Inverters Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University 7

8 Multilevel Inverters : 5-level V an For a m-level inverter we have: Number of switches = 2(m-1) Number of dc-link capacitors = (m-1) Number of clamped diodes = 2(m-2) Voltage across each dc-link capacitor = V DC (m 1) ECEN 613 Rectifiers & Inverters Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University 8

9 Multilevel Inverters - ABB ECEN 613 Rectifiers & Inverters Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University 9

10 Medium Voltage Secondaries Note: A Total of 12- secondaries, only 4- secondaries shown for simplicity ( Phase A ) Utility Input Medium Voltage Adjustable Speed AC Motor Drive: ASI-Robicon Perfect Harmony Inverter Cells, Similar to Phase A N Inverter Cells, Similar to Phase A o Inv. 1a Inv. 1b Inv. 1c a 1 b 1 c 1 n a1 o a1 a 1 b 1 c o Inv. 2a Inv. 2b Inv. 2c a 2 b 2 c 2 n a2 o a2 a 2 b 2 c 2 a i a Inv. 3a Inv. 3b Inv. 3c b i b -7.5 o a 3 b 3 c 3 c i c n a3 o a3 a 3 b 3 c o Inv. 4a Inv. 4b Inv. 4c a 4 b 4 c 4 o a4 n a4 a 4 b 4 c 4 ECEN 613 Rectifiers & Inverters Input current and output voltage is of high quality Complicated multi-winding 60Hz input transformer Single phase inverter dc-link capacitor size is large Modular in construction & employs low voltage devices Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University A B C M 10

11 Toshiba MV Drive ECEN 613 Rectifiers & Inverters Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University 11

12 ECEN 613 Rectifiers & Inverters Dr. Prasad Enjeti, Department of Electrical & Computer Engineering, Texas A&M University

13 Power Electronics for Photovoltaic Applications Dr. Robert S. Balog, PhD PE Assistant Professor, Department of Electrical and Computer Engineering Director, Renewable Energy & Advanced Power Electronics Research Laboratory Robert S. Balog

14 Topics covered in the module 1. Electrical characteristics and modeling of PV 2. Interface requirements 3. Maximum power point tracking, series string vs. module-level, impedance matching 5. Circuit topologies 6. System design and applications 6. Standards and economics 2013 Robert S. Balog

15 Power Electronics for MPPT of PV M. Mirjafari, R. S. Balog, and R. Turan, "Multi-Objective Optimization of the DC-DC Stage of a Module-Integrated Inverter Based on an Efficiency Usage Model," IEEE Journal of Photovoltaics, accepted for publication 21 Jan P. Mazumdar, P. N. Enjeti, and R. S. Balog, "Analysis and Design of Smart PV Modules," IEEE Journal of Emerging and Selected Topics in Power Electronics (JESTPE), available IEEE Xplorer early access, 11 Dec Robert S. Balog 15