CORDIS - EU research results

Intelligent DC/DC converter for fuel cell road vehicles

Final Report Summary - INTELLICON (Intelligent DC/DC converter for fuel cell road vehicles)

The INTELLICON project was based on the concept of replacing the need for on-board vehicular traction battery energy storage having a fuel cell power plant by a super-capacitor. The essential concept is that the fuel cell system provides continuous average power via a unidirectional DC / DC converter provides a regulated DC rail for system stability and on-board energy storage and immediate power demand are provided by a super-capacitor. The super-capacitor acting as a solid-state flywheel used to store cache energy for vehicle acceleration, braking and similar short-term energy flows.

The strategic advantages over current state-of-the-art are identified to be:
- potential reduction in unit capital cost of hybrid power trains;
- significant reduction in the maintenance profile of fuel cell hybrid power trains by replacing batteries with long-life and maintenance free super-capacitors;
- isolation of the fuel cell output from the main DC bus and traction system, thereby isolating energy source from the highly variable load and creating opportunities for greater flexibility in the choice of fuel cell options and independent optimisation of both fuel cell operation and the traction system. Energy source voltage is totally independent of the DC rail;
- general overall improvement in operational safety and reliability of fuel cell systems. The system provides for protection of the fuel cell from adverse operational conditions by making the DC / DC converter 'intelligent'. This feature was developed during the project and continues. Including provision of contaminant warning / protection, hydrogen / air pressure, earth leakage, short-circuit, adverse temperature, super-capacitor condition etc.
- overall reduction of the weight overhead of fuel cell hybrid systems. Achieved by using high energy density DC / DC converter technology and super-capacitor which have a higher specific energy and power density than that of an equivalent advanced battery system by careful topology, packaging and thermal management;
- improves vehicle performance due to optimised power train without compromising energy source;
- the production units of the DC / DC converter will be of modular construction whereby various power handling modules and drivers can each be supplied by the same logic board;
- high efficiency of over 94 % with proactive energy management and Canbus communications;
- the system has been shown to be eminently applicable for plug-in hybrid both thermal engine and fuel cell and battery systems (where the battery is the energy source);
- regulatory and homologation compliance.

There is, however, another key benefit from this novel concept namely that the system architecture together with the novel control algorithms are anticipated to extend the operational life of fuel cells by 100 % or more because the fuel cell is operating over a narrow bandwidth and not subject to highly variable loads. This is also true of battery only systems where the onboard battery source is not subject to dramatic charge and discharge cycling.

The same fundamentals also apply to the application of thermal engine hybrid power trains because by optimum narrow band use gives rise to improving engine consumption i.e. reducing carbon emissions for a given drive cycle over current state of the art.

The project represents a paradigm shift in hybrid power train architecture for the advantages listed. Although, it was originally envisaged for materials handling, airport vehicles, small industrial vehicles and neighbourhood road vehicles the concept is anticipated to find advantage in larger systems light rail for example.