Research On Continuously Variable Transmission Control System Based On DSP

CVT transmission compared with other transmissions has obvious advantages. It can achieve the best match between the engine and external load, and notably improves the automobile fuel oil economy, driving force and driving stability, and resolve the four fundamental problems including saving energy, reducing consumption, safety and the cost thereby, in automobile making industry. Therefore, CVT is a kind of ideal transmission device. In this dissertation, the working theory and the marching on engine of CVT are analyzed, and the mixed fuzzy-PI control strategy is designed, and simulation is done. Based on this control strategy, transmission control unit (TCU) is designed. Study contents concretely as follows:The structure, operating principle and control technique of metal v-belt CVT are analyzed. According to engine output torque and speed rate characteristic of, the best matching problem between the transmission system and engine is analyzed. The scheme that speed ratio controlling affect on the best driving force and the best economy of integrated car is proposed.In order to study the control effect of speed ratio change on fuel economy performance of vehicles under complex working conditions, a mixed fuzzy-PI control strategy is proposed, which realizes effective adjustment to speed ratio and makes the engine always works in ideal working point. An integrated car simulation model including engine, transmission system and speed ratio controller is built. The typical work condition of the vehicle is simulated. Simulation results show that the speed ratio mixed fuzzy-PI controller has a better following characteristics and higher accuracy compared with a conventional fuzzy controller. Even in the case of external disturbance, the target engine speed can still be maintained at the most economic working point. At the same time, speed ratio has better following characteristics in different road conditions. A design scheme of TCU based on TMS320LF2407A chip is introduced. A power circuit, signal collection circuit and output driving circuit are analyzed in detail. Software system is given combining with the TMS320LF2407A characteristic, and makes detailed introduction to every functional subprograme modules being composed of software system.Finally, the functional subprograms are compiled and debugged under integrated development environment CCS2.0, and the feasibility of control strategy is verified.