Abstract: A method and system for dynamically controlling and managing a fuel cell system is provided. The method and system ensures that predetermined operating parameters and conditions are met. This is achieved using programmable on-board hardware that is already available in the fuel cell system and does not require additional components. More specifically, operating characteristics are measured such as the voltage of the weakest cell, the stack output voltage, the stack output current, the current of a battery being charged by the stack and/or the power of the stack. When each of these measurements is taken, a determination is made to find the load change that should be made in order to adjust the stack voltage to achieve a desired goal. In particular, the load on the fuel cell system can be varied by adjusting the duty cycle of the switches within a DC-DC converter that is being operated by an associated microcontroller.

Abstract: This invention presents a method and apparatus for measuring the resistance across a fuel cell stack, a fuel cell array, or an individual fuel cell. The invention employs a fixed load circuit to switch a fixed resistance or to connect a fixed load current to the stack or array. When the load is turned on, the stack voltage is read, then the load is turned off and the stack voltage is read again to determine the voltage jump. A change in resistance is calculated that is related to cell hydration. In accordance with another aspect of the invention, the stack includes a programmable DC-DC switch under PWM microprocessor control. The DC-DC converter is used to switch the load on and off and the voltage jump is read using a sample and hold methodology with an optional instrumentation amplifier and a Kalman filter to determine accurate results for resistance with no additional hardware. The resistance measurements are used to identify and evaluate cell hydration.