Controller Development On Hydro-Mechanical Continously Variable Transmission

Hydro-mechanical variable transmission (HMT) is a new practice of today’s vehicle drive combining two advantages of high power and high efficiency. It not only avoids manufacturing high-power hydraulic components in the field of pure hydraulic transmission, but also achieves continuously variable transmission. The development of HMT controller will lay the foundation for the research of dynamic characteristics, control strategies and road test of the vehicle with HMT.The controller that realizes the speed control inside range and the range changeover control is designed aiming at the follow-up study of HMT in this paper. The main content includes:(1)Based on the analysis of the fundamental structure, principle and characteristics of HMT, the speed regulation method was selected as the HMT control scheme.(2)Hardware circuit of HMT controller was designed, including:vehicle condition signal acquisition circuit, high speed switching valve drive circuit, the range changeover electromagnetic valve drive circuit, variable pump drive circuit, communication interface circuit and so on.(3)Based on the analysis of previous speed control strategy inside range, the increment PID control strategy with integral separation was proposed. The range changeover conditions and the range changeover logics were also derived.(4)The software was written in the integrated development environment CodeWarrior, mainly including:vehicle condition signal sampling program, the speed inside range control program, the range changeover control program, the oil pressure control of range changeover program, communication program, main program.(5)The verification tests of the controller were carried out, the controller designed in this paper is proved to basically meet the control requirements.