The Study On Hydromechatronics Compound Soft-start Variable Speed Drive System

With the development of national economy in recent years，high-power heavymachine is widely applied in various industries.The startup of high-power motor withload will produce a starting current which is5to7times of the rated current and havea great impact on the motor as well as the power grid.The instantaneously shutdownof high-power equipment will bring strong impact to the device.The smooth runningof high-power equipment in different situations is also a big problem.In order tosolve the above problems， it is necessary to apply real controllable softstarting/stepless speed regulation technology to high-power equipment.This paperuses the differential planetary gear train transmission mechanism in combination withthe fluid transmission control technology to control the whole mechanicaltransmission device， which not only can make the non-load starting of main motorpossible， but also can realize the soft starting， stepless speed regulation， softstopping， self-weight downing function et al of working mechanism of heavy loadmechanical equipment by adopting the continuous controllability of fluid drive.Thisarticle can lay good theoretical fundation for controllable mechanical soft starting/speed control technology of high-power equipment，and is of great significance to thedevelopment of the vital common technology of our nation’s heavy load mechanicalequipment.The main work is as following：(1) The working principles of the mechanical-electrical-hydraulic soft startingsystem are studied， the dynamics analysis and mathematical modeling of workingmechnism’s soft starting， soft stopping，self-weight downing stage are done.Thesimulation of the mathematical model is conducted to obtain the variation law ofhydraulic pump’s exit pressure.(2) The three-dimensional assembly model of mechanical transmission system isimported into ADAMS dynamics simulation software to establish its dynamicssimulation model and the simulation test is done.The simulation results show that thesoft starting，soft stopping，self-weight downing of each stage of working mechanismbasically consistent with the design values， which verifies the correctness of themathematical model.(3) The optimization mathematic model is established by setting the volume of high speed planetary gear train，low-speed planetary gear train and bevel gear pair asoptimization targets， and by using the external requirements as constraints.Theoptimization solving process of the mathematical model is done by using the fminconfunction in MATLAB software.The optimal structure parameters are obtained，whichreduce the consumption of metal material and the manufacturing cost.