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Reconfigurable Mixed Battery with Unequal Battery Modules
  • +3
  • Nima Tashakor,
  • Pouyan Pourhadi,
  • Mahdi Bayati,
  • Mohammad Hamed Samimi,
  • Jingyang Fang,
  • Stefan Goetz
Nima Tashakor
Pouyan Pourhadi
Mahdi Bayati
Mohammad Hamed Samimi
Jingyang Fang
Stefan Goetz

Corresponding Author:[email protected]

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Abstract

Contrary to the modules in conventional modular multilevel and cascaded bridge converters with only serial and bypass operation, emerging topologies bring additional parallel inter-module connectivity, introducing sensorless voltage balancing, load current sharing, and enhanced efficiency. However, matching voltages and characteristics is crucial for the modules to allow for a parallel mode between them, but it is not feasible for mixed-type or heterogeneous battery systems. This paper introduces a reconfigurable battery system designed to solve the challenges of integrating batteries with varying characteristics. Using compact coupled inductors and a novel modulation strategy, the system achieves intermediate states between parallel and series modes when dealing with heterogeneous modules. The coupled inductors, with minimal magnetic material and a small footprint, have a negligible common-mode inductance for the high load current and limit circulating currents through high differential-mode inductance. Furthermore, the proposed modulation strategy introduces free DC/DC conversion functionality and enables an efficient bidirectional energy transfer, fully capable of controlling the power exchange between modules widely independently from the output control. This inter-module DC/DC functionality enables effective charge or load balancing among batteries of varying voltages, types, and age. Importantly, the same transistors perform the DC/DC functionality and the output control so that the topology does not need more silicon. Extensive simulations and experiments demonstrate the performance of the system. The proposed system can notably reduce the inductor’s core size by more than 80% with the circulating current as high as one-fifth of the load current. The solution also reduces the cost of the inductor by more than four times. Moreover, the findings demonstrate > 15 % improvement in conduction and > 50 % in switching losses.
30 Jan 2024Submitted to TechRxiv
06 Feb 2024Published in TechRxiv