Workload-driven frequency-aware battery sizing

Despite the wide body of literature on the sizing of energy storage devices available in the domain of electrical energy systems, the problem has not drawn much attention in the area of battery-powered electronic systems. It is well-known that the straightforward method of sizing battery as the product of an expected duration and the average load current always underestimates the actual capacity that the battery can supply. The variability of the workload and of its spectral distribution will in fact affect the effective capacity of battery that cannot be ignored. This paper proposed a methodology to compute the required capacity of a battery based on the properties of the workload; in particular it accounts for both the impact of the distribution of the current load and of its frequencies, and determines corrective factors for both effects to be used for the calculation of the actual capacity. We used a frequency-sensitive circuit-equivalent battery model to validates our method on three synthetic and two real workloads. Simulation results show that even for workload with same average current, the required capacity can be as much as 70% larger than the capacity estimated using a traditional method.