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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Fig. 1 (a), can be used to connect two three-phase electrical systems (input side and output side systems) using nine active branches. Each branch consists of a cascaded connection of full-bridge cells and a branch inductor. This topology was first proposed by R. Erickson and O. Al-Naseem in 2001 [2]. In common with other members of the modular multilevel cascade converter family [1], the M3C can easily reach high voltage ratings as well as significantly reduce voltage harmonics and electromagnetic interference. In addition, the modular structure makes it easier to accomplish construction, maintenance and thermal designs.Initially, the M3C topology was presented and researched without branch inductors. Space vector modulation (SVM) based capacitor-voltage balancing methods are proposed in

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract-The Modular multilevel matrix converter (M3C) is a promising topology for medium-voltage, high-power applications. Due to the modular structure, it is scalable, produces high quality output waveforms and can be fault tolerant. However, the M3C suffers from capacitor-voltage fluctuation if the output frequency is similar to the input frequency. This problem could limit the circuit's application in the adjustable speed drives (ASD). This paper introduces a theoretical analysis in the phasor-domain to find the branch energy equilibrium point of the M3C when operating with equal input and output frequencies. On the basis of this equilibrium point, a branch current reallocation based energy balancing control method is proposed to equalize the energy stored in the nine converter branches. With this novel control method, the M3C can effectively overcome the capacitor voltage fluctuation without using balancing techniques based on common mode voltage or applying reactive power at the input side.

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In more electric aircraft (MEA) weight reduction and energy efficiency constitute the key figures. Additionally, the safety and continuity of operation of its electrical power distribution system (EPDS) is of critical importance. These sets of desired features are in disagreement with each other, because higher redundancy, needed to guarantee the safety of operation, implies additional weight. In fact, EPDS is usually divided into isolated sections, which need to be sized for the worst-case scenario. Several concepts of EPDS have been investigated, aiming at enabling the power exchange among separate sections, which allows better optimization for power and weight of the whole system. In this paper, an approach based on the widespread use of multi-port power converters for both DC/DC and DC/AC stages is proposed. System integration of these two is proposed as a multiport power conversion system (MPCS), which allows a ring power distribution while galvanic isolation is still maintained, even in fault conditions. Thus, redundancy of MEA is established by no significant weight increase. A machine design analysis shows how the segmented machine could offer superior performance to the traditional one with same weight. Simulation and experimental verifications show the system feasibility in both normal and fault operations.

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A novel power electronic transformer (PET) topology w i th mult i port b idi rect i onal resonant DC-DC converters i s proposed where several medium-frequency multi-winding transformers is applied to realize the isolation. The topology is with high power density as well as high efficiency, which is a appropriate solution for electric tracton application like locomotives and high speed EMU trains. The power balancing could be realized by common flux linkage of the transformer, so that the load of the PET ports can be different from each other. Three control strategies of the multi port bidirectional LLC resonant DC-DC converters are proposed for either independent and paralleled secondary DC links with small LC parameter difference. Simulation and experimental results are given to validate the proposed topology and control strategies.