{{Short description|Method of generating high-voltage wave-forms from lower-voltage components}} A '''multi-level converter''' (MLC) or (multi-level inverter) is a method of generating high-voltage wave-forms from lower-voltage components. MLC origins go back over a hundred years, when in the 1880s, the advantages of DC long-distance transmission became evident.<ref>{{cite book |last1=Arrillaga |first1=Jos |title=High Voltage Direct Current Transmission |date=1998 |publisher=Institution of Electrical Engineers |chapter=Chapter 1 |isbn=0852969414 |page=1–9 |edition=Second}}</ref>
Modular multi-level converters (MMC) were investigated by Tricoli et al in 2017. Although their viability for electric vehicles (EV) was established, suitable low-cost semiconductors to make this topology competitive are not currently available (as of 2019).<ref>{{cite journal |last1=Tricoli |first1=Pietro |title=Efficiency assessment of modular multilevel converters for battery electric vehicles |journal=IEEE Transactions on Power Electronics |volume=32 |issue=3 |pages=2041–2051 |date=Mar 2017 |doi=10.1109/TPEL.2016.2557579|bibcode=2017ITPE...32.2041Q |hdl=11311/1031928 |s2cid=8412590 |url=http://pure-oai.bham.ac.uk/ws/files/27674843/07457710.pdf }}</ref>
In 1999, Tolbert described the use of MLC for battery operated electric motors.<ref>{{cite journal |last1=Tolbert |first1=Leon M. |title=Multilevel Converters for Large Electric Drives |journal=IEEE Transactions on Industry Applications |date=Jan–Feb 1999 |volume=35 |issue=1 |pages=36–44 |doi=10.1109/28.740843 |citeseerx=10.1.1.468.9074 }}</ref>
Habib's 2018 review paper<ref>{{cite journal |last1=Habib |first1=Salman |title=Assessment of electric vehicles concerning impacts, charging infrastructure with unidirectional and bidirectional chargers, and power flow comparisons |journal=Int J Energy Res |volume=42 |issue=11 |date=Jan 2018 |pages=3416–3441 |doi=10.1002/er.4033|bibcode=2018IJER...42.3416H |s2cid=104109087 |doi-access=free }}</ref> reviews multi-level inverters (a synonym for MLC) stating the advantages of bi-directional energy flows to power the motor or charge the battery system.
== High-voltage DC converters == HVDC converters typically use series connected switched capacitors blocks. The blocks are switched in or out of the circuit to form the desired waveform, typically three-phase AC.
== Low-voltage DC converters == Hydrogen generation via electrolysis requires DC currents over several thousand amperes, but DC voltages in the range of only 100...400 VDC. A high voltage modular multi-level converter (MMC) can be adapted by connecting a galvanically isolated LLC resonant converter to each module capacitor.<ref>{{Cite book|chapter=11kW, 70kHz LLC Converter Design with Adaptive Input Voltage for 98% Efficiency in an MMC|first1=Roland|last1=Unruh|first2=Frank|last2=Schafmeister|first3=Joachim|last3=Böcker|title=2020 IEEE 21st Workshop on Control and Modeling for Power Electronics (COMPEL) |date=November 30, 2020|pages=1–8|via=IEEE Xplore|doi=10.1109/COMPEL49091.2020.9265771|isbn=978-1-7281-7160-9 |s2cid=227278364 }}</ref> Several half-bridge and full-bridge based MMC topologies are evaluated in.<ref>{{cite conference |last1=Unruh |first1=Roland |title=Evaluation of MMCs for High-Power Low-Voltage DC-Applications in Combination with the Module LLC-Design |book-title=22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe) |date=October 2020 |doi=10.23919/EPE20ECCEEurope43536.2020.9215687 |isbn=978-9-0758-1536-8 |s2cid=222223518 }}</ref> Such a converter can also be used to provide a centralized 400V DC power supply for data centers.
== M<sup>2</sup>LeC == M<sup>2</sup>LeC (pronounced Emlek), is a form of multi-level converter that combines the functions of generating electric motor wave-forms, with battery charging and management in a single set of power electronics hardware, where the various functions are performed through software alone.
== References == {{Reflist}}
Category:Voltage Category:Electrical components