This paper presents a model of a whole polymer electrolyte fuel cell system including the stack, an air compressor, a cooling system, and a power converter. This model allows its integration in a complete hybrid electric vehicle simulation. The level of detail of the model is chosen to enable control rules design, ancillaries sizing, and study of the interaction between the components of the vehicle. This model is formalized with energetic macroscopic representation, thus organized in a unified multidomain graphical description. Experimental results are compared to simulations for validation of the model accuracy.