engleski

Integration of Electrical Systems on a Hybrid Skidder based on Parallelized Low Cost Direct Current Power Converter Array

Off-road vehicles are increasingly being equipped with hybrid electric powertrains in order to improve their fuel economy, and, consequently, to facilitate notable reductions in greenhouse gases emissions. The hybrid electric power-train apparently offers a favorable solution that can meet the above requirements for the propulsion of articulated forestry tractors, also known as skidders, due to the possibility of using a lower- power diesel engine, along with an additional battery storage system and driveline power source (i.e. electric motor). Due to the fact that hybrid electric vehicles utilize additional power from the high-voltage (typically 450V) battery energy storage system for vehicle propulsion, whereas many accessories (radio, lighting and similar) still operate at the low-voltage (24V) direct- current bus, two direct-current electrical systems are commonly present within such hybrid vehicles. Therefore, when the low-voltage bus requires addition power input (e.g. to recharge the low- voltage battery), the higher-voltage and higher capacity battery energy storage system can be used for that purpose by using direct-current to direct-current (DC/DC) power converters. In order to increase the power conversion efficiency and reliability, and also to avoid issues with overheating and reduce the maintenance requirements, a suitable parallel DC/DC converter array may be considered, along with an appropriate control strategy that minimizes the required number of active DC/DC power converters operating in parallel. Having this in mind, this paper investigates the effectiveness of one such parallelized low-cost DC/DC converter array within the electrical power distribution system of a hybrid skidder. The resulting direct-current bus voltage and current control systems have been verified by means of detailed computer simulations and experimentally on the hybrid propulsion system laboratory setup.

DC-DC converter ; power distribution system ; hybrid skidder ; efficiency

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