SiC-based improved neutral legs with reduced capacitors for three-phase four-wire EV chargers

Yang, Peng ORCID: https://orcid.org/0000-0002-8429-7598, Ming, Wenlong ORCID: https://orcid.org/0000-0003-1780-7292, Liang, Jun ORCID: https://orcid.org/0000-0001-7511-449X, Ugalde Loo, Carlos E. ORCID: https://orcid.org/0000-0001-6361-4454, Navaratne, Rukshan, Ellabban, Omar and Ludtke, Ingo 2022. SiC-based improved neutral legs with reduced capacitors for three-phase four-wire EV chargers. IEEE Transactions on Transportation Electrification 8 (2) , pp. 2565-2582. 10.1109/TTE.2021.3138333

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Abstract

An electric vehicle (EV) charger can operate in an autonomous mode to create its own grid by utilizing the EV batteries during grid blackouts. This requires three-phase four-wire inverters as the grid-side ac/dc port of the EV charger to supply unbalanced loads. Although silicon carbide (SiC) MOSFETs can be adopted to increase the power density of these inverters, the second order ripples exhibited on the dc bus caused by unbalanced loads need to be mitigated by a large dc capacitance—increasing the size of inverters. In this paper, an improved neutral leg for three-phase four-wire inverters is presented, which not only provides the neutral current for unbalanced loads like a conventional neutral leg, but also reduces the second order ripples on the dc bus without the need for additional hardware components. Furthermore, it can reduce by 50% the dc capacitance compared to its conventional counterpart. A control strategy featuring power decoupling capability is included for the improved leg. It was built with SiC MOSFETs and experimentally assessed with a three-phase inverter, with results verifying its effectiveness. For completeness, the performance of the improved neutral leg is also evaluated through simulations in PLECS and compared to a conventional neutral leg.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering
Additional Information:	This work is licensed under a Creative Commons Attribution 4.0 License.
Publisher:	Institute of Electrical and Electronics Engineers
ISSN:	2332-7782
Date of First Compliant Deposit:	11 January 2022
Date of Acceptance:	19 December 2021
Last Modified:	05 Dec 2023 02:52
URI:	https://orca.cardiff.ac.uk/id/eprint/146451

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