Research On The Power-assisted Torque Control Algorithm Of Electric Power-assisted Bicycles

In recent years,two-wheel vehicles such as electric bicycle and electric motorcycle driven by electric motors,have gradually become an important part of China's transportation system,and also represent the diversification of electric vehicles.As a new type of high-tech vehicle,Electric Power Assisted Bicycle(EPAC)has “electric power assistance” function and can help riders save strength when starting,climbing or top wind.It deserves scientific research and has broad market prospects.As the core control strategy of EPAC,power-assisted torque control algotithm can affect the comfort of riding directly.It is an obvious problem to provide assistance under conditions of uphill or changing load.So,this paper proposes a torque control approach adaptive to slope and load for EPAC.When the vehicle encounters the disturbance of load changes or uphill road,it can still maintain a stable driving state and achieve a better driving experience.First,According to the system dynamics analysis,the longitudinal dynamics model of EPAC is established.In addition,the torque sensor model and the power-assisted motor model are established as well.Second,a control approach adaptive to slope and load is proposed and applied to EPAC.During the control process,the power-assisted torque can be compensated by comparing the actual model and the nominal model based on the Model-Following Control(MFC).This approach doesn't require complicated estimation for road grade and load.What's more,the control method is proved to be effective and superior by simulations.And the stability of the control system is also verified in theory according to Routh criterion.Third,this paper designs the power-assisted control system to provide hardware foundation for real vehicle verificaition.In terms of hardware,the controller is designed to ensure the reliability and stability of the circuit.In respect of software,it is divided into underlying driver and the upper control.Finally,this paper develops an experimental platform of EPAC to verify the effectiveness of the torque control strategy.The feasibility of the torque sensor is proved by riding test outdoors.According to the simulation results with the same test configurations,the advantages of the algorithm presented in this paper are analyzed and discussed thoroughly.