Engineers at the University of California, Riverside have developed an online energy management system (EMS) based on an evolutionary algorithm for plug-in hybrid vehicles (PHEVs) that they say can improve vehicle fuel efficiency by more than 30%.

A paper describing the research was recently accepted for publication in the journal IEEE Transactions on Intelligent Transportation Systems.

Flow chart of the proposed on-line EMS.Flow chart of the proposed on-line EMS.The advantage of PHEVs, which combine an internal combustion engine (ICE) with an electric motor and a large rechargeable battery, over conventional hybrids is that they can be charged using grid electricity, which reduces their need for fuel. However, improving PHEV efficiency is limited by shortfalls in the EMS which controls the power split between engine and battery when the vehicle switches from all-electric mode to hybrid mode.

The EMS developed and simulated by the researchers combines vehicle connectivity information (such as cellular networks and crowdsourcing platforms) and evolutionary algorithms—a mathematical way to describe natural phenomena such as evolution, insect swarming, and bird flocking.

The research builds on previous work by the team showing that individual vehicles can learn how to save fuel from their own historical driving records. Together with the application of evolutionary algorithms, vehicles will not only learn and optimize their own energy efficiency, but will also share their knowledge with other vehicles in the same traffic network through connected vehicle technology.

The analytical framework consists of information acquisition (from external sources); prediction; optimization; and power split control. Using real-world data to evaluate the strategy, they found that the self-adaptive control strategy used in the proposed system statistically outperforms the conventional binary control strategy with an average of 10.7% fuel savings without considering battery charging opportunity and 31.5% fuel savings when considering charging opportunity.

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