Patent ID: 9419293
Filing Date: 2016-08-16
CPC Classification: B60L,H01M,Y02E,Y02T

Claim Text:
1. A system comprising: a fuel cell system; a switched load configured to be selectively coupled to the fuel cell system at a center frequency such that a first component of a current flow is induced across the fuel cell system when the switched load is coupled to the fuel cell system; an excitation current source configured to induce a second component of the current flow across the fuel cell system at the center frequency; a voltage sensor coupled to the fuel cell system configured to measure a voltage signal associated with the current flow; a current sensor coupled to the fuel cell system configured to measure a current signal associated with the current flow; a filtering system coupled to the voltage sensor and the current sensor configured to receive the voltage signal and the current signal and to generate a corresponding filtered voltage signal and a corresponding filtered current signal; a processing system coupled to the filtering system configured to calculate a high frequency resistance of the fuel cell system based on the filtered voltage and current signals; and wherein the processing system is configured to determine that levels of the filtered voltage and current signals exceed at least one threshold and, in response, cause the excitation current source to induce the second component of the current flow.