Scheduling of dual supercapacitor for longer battery lifetime in safety‐critical embedded systems with power gating

Abstract

The wake up of power gating (PG) components leads to flow of inrush current which quickly discharges the battery. An arrangement of instruction controlled hybrid battery supercapacitor (SC) elongates battery life in systems with PG. The present work improves a batterysingle SC system (BSC) model to its equivalent batterydual SC system (B2SC). Instructions: disconnect battery (db) and connect battery (cb) have been introduced along with architectural support for B2SC. During wakeup db disconnects (i) battery from the PG components, and (ii) either one or both of the SCs from the battery. Hence, simultaneously either both SCs can discharge or one can discharge while the other's charging. While cb connects the battery to the PG components and SCs. A suboptimal version of B2SC (B2SCsopt) is introduced, where the SCs are connected to the PG components requiring higher inrush current while rest remains connected to the battery. The efficacy of the proposed methods are evaluated on cardiac pacemaker, unmanned aerial vehicle and benchmark programmes. B2SC reduces battery ratecapacityeffect (Crate) by an average of 21.87% at the cost of average performance loss of 9.25%. (B2SCsopt) reduces Crate by an average of 29.37% at the cost of average performance loss of 16.87%.