The purpose of this paper is to simulate micro direct methanol fuel cells (DMFCs) for portable electronic devices by means of a non‐linear equivalent circuit based on a fully coupled, dynamic, electrochemical model.
The equivalent circuit accounts for electrochemical reactions and electric current generation inside the catalyst layers, electronic and protonic conduction, fuel crossover across the membrane, mass transport of reactants inside the diffusion layers. The V‐I characteristic of the device is obtained by combining mass transport and electric equations. The transient dynamics is accounted for by an equivalent capacitance, while the slow dynamics by the mass conservation equation. The equivalent circuit is embedded in the Matlab/Simulink® dynamic model of a hybrid system, consisting of a micro fuel cell and a Li‐ion rechargeable battery.
An original equivalent circuit of a passive DMFC suitable for static and dynamic simulations under variable loading conditions is proposed and validated.
The one‐dimensional model of the micro cell does not take into account transverse mass transfer and current density variations in the cell layers, which can be due to non‐homogeneous materials or to the complex dynamics of the convective mass flow in the reservoir and in the room air.
The equivalent circuit can be used for simulating the dynamic performance in realistic operating conditions when the fuel cell is used to supply the electronic equipment through a power management unit.
The DMFC is described from an electrical point of view as a controlled non‐linear generator; such equivalent representation is particularly suited for designing power management units for electronic portable devices.
