Research of two speed DCT electric power-train and control system
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The research for this thesis is based on an international cooperation project with BAIC Motor Electric Vehicle Co. Ltd, UTS and AVL/NTC. It aims to develop a sample of a two speed DCT used in an electric drive system. For the dual clutch’s structural characteristics, one clutch is connected with one gear, so it is very simple to realize two speed driving. Simulation models are built in a co-simulation platform using AMESim and Simulink. Gear ratio selection is processed during the matching of Q60FB and C70GB vehicles. The ratios selected are 2nd and 3rd gear, and the ratios are 8.45 and 5.36. The prototype is modified from a VW 6spd DCT to operate at 2 speeds. The work primarily involves modification of the mechanical part of the gears and shaft, and changing the hydraulic parts. To optimize vehicle dynamics and economic performance, a shifting schedule calculation method for PEVs is provided. This uses a graphical development method and is adapted for the purposes of simulations and experimental work. As long as gear shifts are initiated according to the schedule, the EM will be maintained at a higher efficiency operating region. As a result, the proposed method provides more efficient operations of the PEV. Study of the control algorithm, including the vehicle control algorithm and shift control algorithm, is the core of this thesis. To investigate shift control and its calibration of a two speed DCT electric drive power-train, this thesis analyzes the shifting process. The vehicle control algorithm section follows the judgment of the pure electric multimode algorithm. The shift control section analyses the traditional DCT control shifting algorithm. In addition, the shifting control algorithm is based on motor active braking control. Detailed shifting control algorithms are developed which include power-on and power-off methods. Corresponding simulation analysis has also been carried out. The rig test uses the UTS power-train test bench for the purposes of modification. Calibration and testing works are employed for processing and the test rig mainly calibrates the shift control algorithm, DCT temperature testing, and NEDC and UDDS drive cycles testing. Vehicle integration and testing are finished at BJEV. This is based on the BAIC independent brand car of Q60FB, with two gear DCT prototype mounting and road test calibration. Finally, the project tests dynamic and economic performance.
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