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19 results on '"Nasir Usman"'

6. A Three-Phase Modular Isolated Matrix Converter.

Author

Nasir, Usman, Costabeber, Alessandro, Wheeler, Patrick, Rivera, Marco, and Clare, Jon

Subjects
*MATRIX converters, *MODULAR construction, *MODULAR design, *POWER density, *LOW voltage systems
Abstract

This paper discusses the analysis, design, and experimental validation of a modular isolated matrix converter (MIMC), including modulation, commutation, and control. The MIMC topology is a single-stage high power density ac–ac converter, which is attractive for traction applications and space-restricted low voltage (LV) or medium voltage (MV) future distribution networks. The topology under study utilizes bidirectional switches based dual-active-bridge cells as basic building blocks. A single cell would have limited practical application as the output frequency is locked to the input one. On the contrary, the repetition of single cells proposed in the MIMC extending the matrix converter concept, achieves variable frequency operation while also providing a modular structure. However, the presence of medium frequency transformers in each cell poses additional challenges for modulation and safe commutation that are discussed and solved in this paper. Experimental results from a proof-of-concept 6 kW laboratory scale prototype validate the practical feasibility and the operation of the MIMC. [ABSTRACT FROM AUTHOR]

Published
2019
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19. A leakage-inductance-tolerant commutation strategy for isolated AC/AC converters

Author

Nasir, Usman, Costabeber, Alessandro, Rivera, Marco, Wheeler, Pat, Clare, Jon, Nasir, Usman, Costabeber, Alessandro, Rivera, Marco, Wheeler, Pat, and Clare, Jon

Abstract

This paper proposes a generalised commutation strategy suitable for matrix-based isolated AC/AC conversion stages in Solid State Transformers for use whenever there is nonnegligible leakage inductance in the isolation transformer. The standard 4-step commutation used in matrix converters can no longer be applied when transformer leakage inductance is present, as overrated switching devices or dissipative snubbers would be necessary, reducing the attractiveness of the topologies that include matrix-based isolated AC/AC stages. A case study of a single-phase AC/AC converter has been investigated in detail to demonstrate the application of the proposed commutation method to a topology that has recently been identified as the potential building block for future multi-modular AC/AC converters for grid applications. The proposed leakage-inductance-tolerant commutation strategy is based on the definition of a current decoupling phase in the commutation sequence and only needs suitable timing of the commutation steps, without high bandwidth voltage or current measurements. Matching simulations and experimental results from a 3kW laboratory scale prototype are presented to support the effectiveness of the proposed strategy.

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