Research On The Ratio Control Of Metal Belt CVT Based On DSP2407

The Metal Belt CVT as vehicle's ideal transmission, has extensive development future and market space. When compared with the widely used automatic transmission (AT), it has many advantages, such as the performance is good, the structure is simple, the price is low and can realize vehicle's continuously variable speeds. Among CVT's control system, speed ratio control is one of the key technologies. Through control the stability of speed ratio, can make the vehicle according to driver's intention automately realize dynamic optimum matching between vehicle's running resistance and engine's output power. In this way, it can exert vehicle's fuel economy and dynamic performance to limiting condition, meeting its requirement on fuel economy and dynamic performance. So this paper makes some research on the stability of speed ratio control of CVT.In order to make a general outline on CVT, the first chapter introduces CVT's development condition, internal actuality and development trend. Then analyses CVT's merit and key technologies, and indicate that in order to guarantee favorable entire car performance, speed ratio control is the key. Finally, confirms this paper's research sense and research content.For the purposes of realizing the theory of speed-ratio control of CVT. The second chapter, analyses CVT's basic structure and gearshift theory first. Then studies the principle of speed ratio control, analyses the strategy and the method to realize the speed ratio control, and according to the practical situation of our test, ascertain the method of rotating speed instead. Finally, disign the speed ratio controller with PID control method and control procedure flow diagram.In order to study the control effect of speed ratio control of CVT vehicle, in the third chapter, I establishes engine simulation model, cvt - power train simulation model and ratio control with PID method model, and combines them together to get the Matlab Simulink model of CVT entire car with PID control method. Then according to the established simulation model towards CVT entire car at ramp starting, ramp acceleration and circulation working condition and proceeding contrast simulation analyses, check speed ratio PID controller 's control effect.With the development of technology, the use of electrical control system is becoming wider and wider. The Electronic Control Unit (ECU) is the core of control system of CVT. In the forth chapter ,in order to build the control system of CVT,I use the DSP2407. The basis of the ECU is the hardware which includes the micro electronic circuit and the peripheral equipments, including power assembly system, loading system, sampling system etc. And write the software diagram according to speed ratio control clew.In order to check the effect to speed ratio stability of speed ratio control theory as well as control strategy, I ave done a great deal of test adopting different control strategy at Lubao test car,and make contrast analysis of test result of speed ratio control , and adopted better control strategy to do tracking test, step tracking test , acceleration text as well as cycle working condition test at different throttle valve and different load, verify check established control theory as well as control strategy met the control requirement of speed ratio stability even better.