Modeling and ratio control of an electromechanical continuously variable transmission
A new type of electromechanical continuously variable transmission (EMCVT) was investigated. The EMCVT uses a direct current (DC) motor to push the driving pulley, which in turn changes the transmission ratio without a hydraulic system. This paper introduces the principle of the EMCVT and establishes a dynamic ratio control model. Ratio control strategies using both position and speed closed loop control are proposed. Simulation results show that the simulation ratio curves of the EMCVT follow pre designed ratios well for ramp and sine curves. Control software is based on MATLAB/Simulink/Stateflow and MotoHawk platforms. A prototype vehicle equipped with an EMCVT has been developed. Vehicle test results show that the control performance of the EMCVT satisfies the requirements of vehicle operation. The effectiveness of the EMCVT ratio control strategy proposed in this paper is validated with test data for the prototype vehicle.