Design For Power System Of Fuel Cell/Battery Hybrid Forklift

As a handing tools in the modern logistics and material industry, forklift has played an important role in every material system. Currently, the forklift trucks on the market could be mainly divided into internal combustion forklifts and electric forklifts, but the serous problems of them have severely limited the application area and further development for both of them,such as the exhaust pollution and excessive nosie for the internal combustion forklifts and poor battery life, high maintenance costs, low efficiency for electric forklifts. Therefore, the application of new energy and new technology on this important project vehicles is so meaningful for both improving the working environment and production efficiency.As one of the new energy, the Proton Exchange Membrane Fuel Cell (PEMFC) has so much great features. Besides clean and high efficiency, the advantages, such as low working temperature, fast respose and long working life, are all exile for exiting forklifts. Therefore, replacing the power system with the PEMFC for forklifts is an effective way to solve the exiting forklift problems.Firstly, on the basis of actual measurements and analysis of electric forklift operating conditions, the paper choosed the air-cooled and self-humidifying PEMFC as a main power and the lead-acid battery as a supplemented power in the hybrid system.And based on the analysis of system structure, self-humidifying theory and control methods, this paper established the model of the PEMFC system, including air supply system model, PEMFC stack dynamic mechanism model, PEMFC dynamic voltage model and the PID control model for stack temperatue.The accuracy of these models has been verified by comparing the simulation results with the experimental data and manual data.Secondly, in order to determine the power level of the PEMFC and rated capacity of the battery and ensure the same performance of fuel cell forklift and original ones, this paper deteminded the satisfied hybrid degree range by calculation and measurement. In order to reduce the initial cost,4kW air-cooled and self-humidifing PEMFC and 240Ah lead-acid battery have been selected to build the hybrid forklift power system. Building a hybired system model on MATLAB/SIMULINK platform and the simulation results showed that the selected power souce could meet the forklift performance and greatly increase the mileage, which meet the design and use requirement.Finally, through hardware design and selection, using Labiew software to prepare the corresponding control program, a air-cooled and self-humidifying PEMFC test platform has been build,which design for Ballard company FCgen(?)1020ACS series 2kW air-cooled self-humidifying PEMFC. Based on the PEMFC test platform, build a fuel cell/battery hybrid forklift simulation platform composed by 2kW PEMFC and 110Ah lead-acid battery. Experimental results showed that power-follow type of energy management strategy could effectively distribute the power between the PEMFC and the lead-acid battery, and the SOC is maintained at the desired level.