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Integrated reciprocal conversion with selective direct operation for energy harvesting systems

Savanth, Parameshwarappa Anand, Kumar, Weddell, Alexander, Myers, James, Flynn, David and Al-Hashimi, Bashir (2017) Integrated reciprocal conversion with selective direct operation for energy harvesting systems IEEE Transactions on Circuits and Systems I: Regular Papers, pp. 1-10. (doi:10.1109/TCSI.2017.2707304).

Record type: Article


Energy harvesting IoT systems aim for energy neutrality, i.e. harvesting at least as much energy as is needed. This however, is complicated by variations in environmental energy and application demands. Conventional systems use separate power converters to interface between the harvester and storage, and then to the CPU system. Reciprocal power conversion has recently been proposed to perform both roles, eliminating redundancy and minimizing losses. This paper proposes to enhance this topology with ‘selective direct operation’, which completely bypasses the converter when appropriate. The integrated system, with 82% bidirectional conversion efficiency, was validated in 65nm CMOS with only the harvester, battery and decoupling capacitors being off-chip. Optimized for operation with cm² photo-voltaic cell and a 32-bit sub-threshold processor, the scheme enables up to 16% otherwise wasted energy to be utilized to provide >30% additional compute cycles under realistic indoor lighting conditions. Measured results show 84% peak conversion efficiency and energy neutral execution of benchmark sensor software (ULPBench) with cold-start capability.

PDF Integrated Reciprocal Conversion with Selective Direct Operation for Energy Harvesting Systems - Accepted Manuscript
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Accepted/In Press date: 12 May 2017
Published date: 14 June 2017
Organisations: Electronics & Computer Science, Faculty of Physical Sciences and Engineering, EEE, Southampton Marine & Maritime Institute


Local EPrints ID: 411741
ISSN: 1549-8328
PURE UUID: 67e0eee1-fd0e-4df7-a71b-27bd8fc6fe9a
ORCID for Alexander Weddell: ORCID iD

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Date deposited: 23 Jun 2017 16:31
Last modified: 13 Sep 2017 04:01

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Author: Parameshwarappa Anand, Kumar Savanth
Author: Alexander Weddell ORCID iD
Author: James Myers
Author: David Flynn

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