Automotive DC-DC bidirectional converter made with many interleaved buck stages

TLDR

Interleaving reduces filter size, improves dynamic response, and enhances power management, and is employed in dual‑battery vehicle bidirectional DC‑DC converters with three‑to‑five parallel buck stages. The paper proposes using many parallel phases with digital control to enable new technological possibilities. The authors implement a bidirectional DC‑DC converter with many interleaved buck stages controlled digitally. Two 1000‑W prototypes built with SO‑8 transistors demonstrate that FPGA‑based digital control eliminates current loops and simplifies the control stage.

Abstract

Interleaving technique is used in some applications due to its advantages regarding filter reduction, dynamic response, and power management. In dual battery system vehicles, the bidirectional dc-dc converter takes advantage of this technique using three-to-five paralleled buck stages. In this paper, we propose the use of a much higher number of phases in parallel together with digital control. It will be shown that this approach opens new possibilities since changes in the technology are possible. Thus, two 1000-W prototypes have been designed using surface mount technology devices (SO-8 transistors). An additional important feature is that due to the accuracy of the digital device [field-programmable gate array (FPGA)], current loops have been eliminated, greatly simplifying the implementation of the control stage.