A 21 kW Unfolding-Based Single-Stage AC-DC Converter for Wireless Charging Applications


This paper introduces a single-stage grid-tied ac-dc conversion system designed for wireless charging applications. The proposed system employs a T-type converter to process soft dc-link voltages that are generated by a 3-ϕ Unfolder. To achieve multiple control-related tasks simultaneously, such as input power factor correction and output power regulation, a modulation scheme is presented for the high-frequency T-type converter. The T-type converter-based soft-dc to dc system is modeled using the phasor transformation technique, and closed-loop control analysis is performed to effectively regulate the battery current. Additionally, in order to facilitate power level scalability, a modular architecture is proposed, and a board with dimensions of 26.2 in (L) × 13.2 in (W) × 4.5 in (H), including the cold plate, is designed to house three T-type converters, each rated for 21 kW of output power. Hardware results of a 21 kW prototype are presented, based on a single T-type module. The prototype demonstrates an ac-dc efficiency from the grid to the battery of ~96%, and a grid current total harmonic distortion of 1.27%. To demonstrate the modular structure for multiple T-type converters operated in tandem, six T-type converter modules are tested in parallel, and corresponding hardware results are presented as well.

See publication:
This publication pertains to:
Charging Stations
Publication Authors:
  • Aditya Zade
  • Chakridhar Reddy Teeneti
  • Mahmoud Mansour
  • Shubhangi Gurudiwan
  • Bryce Hesterman
  • Hongjie Wang
  • Regan Zane
It appeared in:
Peer-reviewed technical journal
Single-stage ac-dc conversion, Unfolder, T-type converter, sensorless power factor correction (PFC), small-signal phasor modeling, battery charger, electric vehicles (EV), wireless power transfer (WPT)