This paper presents design consideration and performance analysis of novel reduced parts online three-phase uninterruptible power supply (UPS) system. The proposed UPS system is based on reduced switch count dual bridge matrix converter. It employs only six power switches and results in reducing the cost of the system compared to conventional online UPS topologies, while achieving excellent performance. The performance of the proposed system is evaluated through simulation in terms of input/output waveforms quality and shows the viability of topology. 1. Introduction Protecting sensitive loads like medical facilities, life supporting systems, data centers, telecommunication systems, and industrial processing systems are the main purpose of implementing uninterruptible power supplies (UPSs system) [1]. UPS system has to provide distortion free, high quality waveforms in order to ensure the reliable operation of the load, regardless of quality of the AC power source [2]. Different types of UPS systems are developed since the advent of UPS concept. Among these types, the online UPS is the most common type for low to medium power applications due to its superior performance such as high tolerance to the input voltage variation and precise regulation of the output voltage [3]. However, conventional online UPS topology employs big number of switches and as a consequence, suffers from high cost, which stops it from adopting in some cost sensitive applications like personal computers. So the idea of developing different topologies to reduce the cost of UPS systems attracts researcher’s attention [4]. In general, the cost reduction is achieved by developing topologies in order to [5](i)reduce the number of power switches,(ii)replace power switches with diodes, because diodes are cheaper than active power switches. Employing the mentioned methods would further reduce the cost by eliminating the circuitry for driving power switches and simplifying the control circuit:(i)lowering the voltage stress across power switches,(ii)eliminating passive components like transformers, capacitors, and inductors. Removing bulky passive elements and lowering the number of power switches would bring some advantages like greater compactness and higher reliability. This paper present the design and performance analysis of a new online three-phase UPS system based on dual bridge matrix converter topology. The concept of reducing the number of switches is applied by using 9 switch dual bridge matrix converter. Further switch reduction is obtained by using capacitor midpoint connection
References
[1]
A. Emadi, A. Nasiri, and S. B. Bekiarov, Uninterruptible Power Supplies and Active Filters, CRC Press, 2005.
[2]
H. R. Karshenas and M. Niroomand, “Design and implementation of a single phase inverter with sine wave tracking method for emergency power supply with high performance reference,” in Proceedings of the 8th International Conference on Electrical Machines and Systems (ICEMS '05), pp. 1232–1237, September 2005.
[3]
M. Niroomand and H. R. Karshenas, “Hybrid learning control strategy for three-phase uninterruptible power supply,” IET Power Electronics, vol. 4, no. 7, pp. 799–807, 2011.
[4]
M. Niroomand and H. R. Karshenas, “Design and implementation of a new hybrid learning control strategy for three-phase UPS,” in Proceedings of the 11th International Conference on Electrical Machines and Systems (ICEMS ;08), pp. 1732–1737, October 2008.
[5]
A. Nasiri, S. B. Bekiarov, and A. Emadi, “Reduced parts three-phase series-parallel UPS system with active filter capabilities,” in Proceedings of the 38th IAS Annual Meeting, IEEE Industry Applications Conference, vol. 2, pp. 963–969, October 2003.
[6]
M. Niroomand and H. R. Karshenas, “Review and comparison of control methods for uninterruptible power supplies,” in Proceedings of the Power Electronic & Drive Systems & Technologies Conference (PEDSTC '10), pp. 18–23, IEEE, 2010.
[7]
A. Nasiri, “Digital control of three-phase series-parallel uninterruptible power supply systems,” IEEE Transactions on Power Electronics, vol. 22, no. 4, pp. 1116–1127, 2007.
[8]
H. R. Karshenas and M. Niroomand, “Analysis and comparison of two control strategies for three-phase series-parallel UPS,” in Proceedings of the 11th International Conference on Electrical Machines and Systems (ICEMS '08), pp. 1726–1731, October 2008.
[9]
J. Holtz and U. Boelkens, “Direct frequency converter with sinusoidal line currents for speed-variable AC motors,” IEEE Transactions on Industrial Electronics, vol. 36, no. 4, pp. 475–479, 1989.
[10]
L. Wei and T. A. Lipo, “A novel matrix converter topology with simple commutation,” in Proceedings of the 36th IAS Annual Meeting, pp. 1749–1754, October 2001.
[11]
J. W. Kolar, M. Baumann, F. Schafmeister, and H. Ertl, “Novel three-phase AC-DC-AC sparse matrix converter,” in Proceedings of the 17th Annual IEEE Applied Power Electronics Conference and Expositions, pp. 777–791, Dallas, Tex, USA, March 2002.
[12]
P. W. Wheeler, J. Rodríguez, J. C. Clare, L. Empringham, and A. Weinstein, “Matrix converters: a technology review,” IEEE Transactions on Industrial Electronics, vol. 49, no. 2, pp. 276–288, 2002.
[13]
J. W. Kolar, F. Schafmeister, S. D. Round, and H. Ertl, “Novel three-Phase AC-AC sparse matrix converters,” IEEE Transactions on Power Electronics, vol. 22, no. 5, pp. 1649–1661, 2007.
[14]
L. Wei, T. A. Lipo, and H. Chan, “Matrix converter topologies with reduced number of switches,” in Proceedings of the IEEE 33rd Annual Power Electronics Specialists Conference (PESC '02), pp. 57–63, June 2002.
[15]
C. Klumpner, M. Lee, C. Pitic, P. Wheeler, and P. Zanchetta, “A new three-level indirect matrix converter with reduced number of switches,” in Proceedings of the IEEE Industry Applications Conference 42nd Annual Meeting, pp. 186–193, September 2007.
[16]
L. Wei, T. A. Lipo, and H. Chan, “Robust voltage commutation of the conventional matrix converter,” in Proceedings of the IEEE 34th Annual Power Electronics Specialists Conference, pp. 717–722, June 2003.
