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This paper presents a system configuration for transformer-less grid integration of large-scale charging infrastructures for electric vehicles (EVs) with wireless inductive charging. The proposed configuration relies on a Modular Multilevel Converter (MMC) topology as the grid interface of the charging infrastructure, where one wireless EV charger can be supplied from each individual module. This system topology could provide significant reduction in footprint and complexity of cable installations by allowing for transformer-less connection and direct integration with the medium voltage distribution grid. The requirements for power flow management when charging EVs that are unevenly distributed within the infrastructure are evaluated analytically. On this basis, a control strategy is presented for ensuring horizontal and vertical energy balancing among the MMC arms, and voltage balancing among the modules of each arm. Time-domain simulations demonstrate how the system can operate with severe unbalances resulting from different number and location of charging EV s. © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

The prospect of future multivendor HVDC systems has led to concerns about interoperability between converter terminals based on different technologies. This paper investigates the interoperability of converter terminals in a small-scale experimental setup, consisting of two 2-level (2L) Voltage Source Converters (VSCs) and two Modular Multilevel Converters (MMCs) with different number of half-bridge sub-modules in each arm. The laboratory setup is utilized to demonstrate interoperability of a 2-level VSCs and an MMCs when operated in parallel on the dc-side as well as in parallel at a common connection point in an ac grid. Experimental results are presented for the investigated 4-terminal configuration with one 2L VSC controlling the dc voltage and all other converters controlling their active power flow. The presented results give an additional empirical confirmation that topological differences between properly designed converter terminals should have limited influence on system level operation and system interoperability of MT HVDC systems Interoperability of Modular Multilevel Converters and 2-level Voltage Source Converters in a Laboratory-Scale Multi-Terminal DC Grid

This paper presents a driver topology intended for WBG devices with the goal of improving the switching performance. In particular, the initial delay time of the switching transient was targeted. In high power and high frequency bridge converters, the dead time causes output voltage waveform distortion and increases losses. Shorter delay time leads to shorter dead time requirement. Simulations show that the delay time can be minimised by correctly implementing the suggested driver stage. For the experimental validation, an improvement of 6-8 ns was demonstrated while keeping the same di/dt and dv/dt as a conventional gate driver. The improvement increases with increasing gate resistance. © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.