Solid-state transformer-based new traction drive system and control

Abstract

A new type of traction drive system consisting of solid-state traction transformer (SSTT), inverter unit, auxiliary inverter, traction motor and other key components is built in order to suit the demand of developing the next-generation electric traction system which will be efficient and lightweight, with high power density. For the purpose of reducing system volume and weight and improving efficiency and grid-side power quality, an efficient SSTT optimized topology combining high-voltage cascaded rectifiers with high-power high-frequency LLC resonant converter is proposed. On this basis, an integrated control strategy built upon synchronous rotating reference frame is presented to achieve unified control over fundamental active, reactive and harmonic components. The carrier-interleaving phase shift modulation strategy is proposed to improve the harmonic performance of cascaded rectifiers. In view of the secondary pulsating existing in a single-phase system, the mathematical model of secondary power transfer is built, and the mechanism of pulsating voltage resulting in beat frequency of LLC resonant converter is revealed, so as to design optimum matching of system parameters. Simulation and experimental results have verified that the traction system and control scheme mentioned in this paper are reasonable and superior and that they meet the future application requirements for rail transit.

Key words： solid-state traction transformer; high-voltage cascaded rectifier; LLC resonant converter; synchronous rotating reference frame; carrier-interleaving phase shift control; secondary pulsating voltage; beat frequency

References

1 Fu Y. The research of non-power frequency traction transformer conversion system based LLC resonant conversion. Thesis for the Master’s Degree. Chengdu: Southwest Jiaotong Uninversity, 2015

2 Kouro S, Malinowski M, Gopakumar K, Recent advances and industrial applications of multilevel converters. IEEE Transactions on Industrial Electronics, 2010, 57(8): 2553–2580

3 Allebrod S, Hamerski R, Marquardt R. New transformerless, scalable modular multilevel converters for HVDC-transmission. In: Proceedings of IEEE Power Electronics Specialists Conference. Rhodes: IEEE, 2008, 174–179

4 Song Q, Liu W, Li X, A steady-state analysis method for a modular multilevel converter. IEEE Transactions on Power Electronics, 2013, 28(8): 3702–3713

5 Glinka M, Marquardt R. A new AC/AC multilevel converter family. IEEE Transactions on Industrial Electronics, 2005, 52(3): 662– 669

6 Inoue S, Akagi H. A bidirectional isolated DC&DC converter as a core circuit of the next-generation medium-voltage power conversion system. IEEE Transactions on Power Electronics, 2007, 22(2): 535–542

7 Krismer F, Kolar J W. Accurate power loss model derivation of a high-current dual active bridge converter for an automotive application. IEEE Transactions on Industrial Electronics, 2010, 57(3): 881–891

8 Nymand M, Andersen M A E. High-efficiency isolated boost DC-DC converter for high-power low-voltage fuel-cell applications. IEEE Transactions on Industrial Electronics, 2010, 57(2): 505–514

9 Weigel J, Ag A N S, Hoffmann H. High voltage IGBTs in medium frequency traction power supply. In: Proceedings of 13th European Conference on Power Electronics and Applications. Barcelona: IEEE, 2009

10 Feng J, Chu W Q, Zhang Z, Power electronic transformer based railway traction systems: Challenges and opportunities. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2017, PP(99): 1

11 Zhao C, Dujic D, Mester A, Power electronic traction transformer—Medium voltage prototype. IEEE Transactions on Industrial Electronics, 2014, 61(7): 3257–3268

12 Zhao C, Weiss M, Mester A, Power electronic transformer (PET) converter: Design of a 1.2 MW demonstrator for traction applications. In: Proceedings of 2012 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM). Sorrento: IEEE, 2012, 855–860

13 Dujic D, Mester A, Chaudhuri T, Laboratory scale prototype of a power electronic transformer for traction applications. In: Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE 2011). Birmingham: IEEE, 2011, 1–10

14 Dujic D, Steinke G K, Bellini M, Characterization of 6.5 kV IGBTs for high-powermedium-frequency soft-switched applications. IEEE Transactions on Power Electronics, 2014, 29(2): 906–919

15 Besselmann T, Mester A, Dujic D. Power electronic traction transformer efficiency improvements under light-load conditions. IEEE Transactions on Power Electronics, 2014, 29(8): 3971–3981

16 Falcones S, Mao X, Ayyanar R. Topology comparison for solid state transformer implementation. In: Proceedings of 2010 IEEE Power and Energy Society General Meeting. Minneapolis: IEEE, 2010, 1–8

17 Shi J, Gou W, Yuan H, Research on voltage and power balance control for cascaded modular solid-state transformer. IEEE Transactions on Power Electronics, 2011, 26(4): 1154–1166

18 Zhao T, Wang G, Bhattacharya S, Voltage and power balance control for a cascaded H-bridge converter-based solid-state transformer. IEEE Transactions on Power Electronics, 2013, 28(4): 1523–1532

19 Huber J E, Kolar J W. Common-mode currents in multi-cell solid-state transformers. In: Proceedings of 2014 International Power Electronics Conference. Hiroshima: IEEE, 2014, 766–773

20 Marchesoni M, Novaro R, Savio S. AC locomotive conversion systems without heavy transformers: Is it a practicable solution? In: Proceedings of the 2002 IEEE International Symposium on Industrial Electronics. IEEE, 2002, 4: 1172–1177

21 Dujic D, Kieferndorf F, Canales F. Power electronic transformer technology for traction applications—An overview. Electronics, 2012, 16(1): 50–56

22 Oliveira D S, de A Honorio D, Barreto L H S C, A two-stage AC/DC SST based on modular multilevel converter feasible to AC railway systems. In: Proceedings of 2014 Twenty-Ninth Annual IEEE Applied Power Electronics Conference and Exposition (APEC). Fort Worth: IEEE, 2014, 1894–1901

23 Feng X. AC Electrical Drives & Control System. Beijing: Higher Education Press, 2009, 272–273 (in Chinese)

24 Zhou M, You X, Wang C, Switching angle calculation and harmonic analysis of current harmonic minimum PWM. Proceedings of the CSEE, 2014, 34(15): 2362–2370 (in Chinese)

25 Gou B, Feng X, Song W, Analysis and suppression of beat phenomenon for railway traction converters and motors. Proceedings of the CSEE, 2013, 33(9): 55–63 (in Chinese)

26 Liu H, Jiao Y, Ming D. Unified power quality controller based on synchronous rotating coordinates. High Power Converter Techno-logy, 2015, 4: 39–43

27 Jiang Y, Cao Y, Gong Y. Research on the cascade multilevel inverter based on different carrier phase-shifted angle. Proceedings of the CSEE, 2007, 27(1): 76–81 (in Chinese)

28 Holmes D G, McGrath B P. Opportunities for harmonic cancellation with carrier-based PWM for two-level and multilevel cascaded inverters. IEEE Transactions on Industry Applications, 2001, 37: 564–582

29 Salam Z, Goodman C. Compensation of fluctuating DC link voltage for traction inverter drive. In: Proceedings of IEEE Sixth International Conference on Power Electronics and Variable Speed Drives. Nottingham: IEEE, 1996: 390–395

30 Wang J, Lu X, Zhang F, Low frequency input current ripple analysis and reduction in a single phase inverter with two-stage structure. Proceedings of the CSEE, 2012, 32(6): 10–16 (in Chinese)

31 Kadavelugu A, Bhattacharya S. Design considerations and deve-lopment of gate driver for 15 kV SiC IGBT. In: Proceedings of 2014 Twenty-Ninth Annual IEEE Applied Power Electronics Conference and Exposition (APEC). Fort Worth: IEEE, 2014, 1497–1501

32 Kadavelugu A, Bhattacharya S, Ryu S H, Understanding dv/dt of 15 kV SiC N-IGBT and its control using active gate driver. In: Proceedings of 2014 IEEE Energy Conversion Congress and Exposition (ECCE). Pittsburgh: IEEE, 2014, 2213–2220