Loss Reduction at Partial Loads of Multi-Level DAB Converters Using Adjusted Switching Patterns
Journal article, 2023

A three-phase ($3\boldsymbol{\phi }$) dual-active-bridge (DAB) dc-dc converter built with a medium frequency transformer with $\Delta$Y-connected windings has low efficiency and low transformer utilization in partial loads. This makes the $3\boldsymbol{\phi }$-$\Delta$Y-DAB less attractive for applications where the performance at partial loads is crucial. This paper presents control strategies utilizing extra degrees of freedom provided by multi-level converters to minimize the RMS current and improve the partial load operation of the $3\boldsymbol{\phi }$-$\Delta$Y-DAB converter. The duration of the zero-level voltage of the Y-side is adjusted with the help of multi-level converters, and the $\Delta$-side dc-link voltage is controlled externally. It is shown that the RMS current can be reduced by $27 \,\%$ at no-load by increasing the duration of the zero-level voltage of the Y-side. In addition, the turn-on and turn-off currents of the switches of the Y-side can be decreased drastically for power levels below $42 \,\%$ of the nominal power. Considerable performance improvements can be accomplished by combining $\Delta$-side dc-link reduction with the Y-side duty cycle variation. It is shown that the RMS current at no-load can be reduced by $100 \,\%$ to zero. This is also validated by measurements where more than $90 \,\%$ reduction in the RMS current is observed at no-load. Moreover, a dramatic decrease in the turn-on and turn-off currents of the switches of both bridges is achieved. Measurements highlighted a factor of nine reduction in no-load turn-off currents of the primary bridge. Moreover, a loss split calculation shows that the semiconductor losses can be decreased by $94 \,\%$ and $81 \,\%$ at $5 \,\%$ and $10 \,\%$ of nominal power, respectively.

Harmonic analysis

transformer winding connection

dual-active-bridge (DAB)

Transformers

Windings

multi-level converters

harmonic analysis

Wind turbines

Topology

dc-dc power conversion

zero voltage switching

Multilevel converters

Bridge circuits

Author

Babak Alikhanzadehalamdari

Chalmers, Electrical Engineering, Electric Power Engineering

Torbjörn Thiringer

Chalmers, Electrical Engineering, Electric Power Engineering

Yuriy Serdyuk

Chalmers, Electrical Engineering, Electric Power Engineering

IEEE Transactions on Industry Applications

0093-9994 (ISSN) 1939-9367 (eISSN)

Vol. 59 5 6312-6323

Subject Categories

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1109/TIA.2023.3290573

More information

Latest update

11/21/2023