Study Of CVT Rapid Control Prototyping

It is well known that transmission plays an important role in automobile: it transmits the input torque from power source to the output shaft with certain ratio, and it should have neutral or reverse. The more ratios the transmission has, the better automobile's dynamic and economical performance. So its performance has great effect to the whole power-line system. Because of conventional transmissions' limited levels and stable ratios, it is difficult to control them, particularly in dynamic and economical performance of automobiles which are equipped internal combustions (IC). The use of automatic transmission (AT) made it possible that the ratios continuous variety and it made IC worked in high efficient areas. But because of the bad efficient of AT key component, torque converter, the economical performance of auto is not better. The use of CVT is curbed because of its low capacity. With the development of technology, there is a trend that more and more CVT has been equipped. Therefore it is more important to research and develop control system and strategy with computers because the ratio control is the central.This paper begins with the operation theory of the continuous variable transmission (CVT), common control strategy and control means. Then the basic theory of semi-hardware simulation is given and the research and development (R&D) tools in this paper is also introduced; the model of the CVT hydraulic control system for real-time simulation has been established and the algorithm has also been studied.It is this paper's core that how to model CVT for real-time simulation and simulate the rapid control prototyping (RCP). Base on the results of CVT tests, the hardware of clamp control and ratio control system and PID controllers have been modeled in chapter 5. In order to get the controllers' parameters, the system's step response has been studied when the parameters are changed in off-line simulation. When off-line simulation, the differenc of differential coefficients changes the step-type of system. It is converted from higher-damp system to lower-damp system. And there is overrun. Base on the real hardwares' limits, the parameters of controllers are decided.Through MATLAB toolbox of RTW and the real-time simulation system dSPACE, PWM signals have been achieved and the real-time simulation of CVT has been made. From the simulation results, we can come to a conclusionthat the model is valid.