Research On Test Bench Of Pure Electric Vehicle Power System

Depending on models and uses of different vehicles, power performance of thedrive system should be differently designed in electric vehicles R&D(research anddevelopment) process, to maximize the speed of R&D. Test bench of pure electricvehicle power system can conduct drive system performance test and also can simulateelectric vehicle running resistances and inertia by providing the torque. In the earlyelectric vehicle research and development, as a physical simulation platform it can beable to provide test data to shorten the pure electric vehicle development time. Thepaper is mainly focus on the following work:The various running resistances affecting the running of pure electric vehicles wasanalyzed, then pure electric vehicle kinetics model was established. Pure electricvehicle inertia simulation requires that the inertia of the electric vehicle to be convertedto the motor-driven side. In the project the convert coefficience which convert therotating mass to translational quality was commonly used. In accordance with theprinciple of conservation of energy in the inertia convert before and after the formuladerivation, the conversion formula that the electric vehicle inertia was converted torotational inertia of the motor-driven side.For the complex resistance characteristics of pure electric vehicle inertiasimulation test bench and torque disturbance produced by axes not aligned on testbench, speed closed-loop vector control method applied to torque loading motor wasproposed. It compensated the bench resistance, torque disturbance and inertia deviationautomatically, and it solved the simulation deviation produced by torque controlmethod, in which rotation inertia of test bench used in control program is differentfrom the actual inertia. Speed control method on test bench works as follows: driveunit of the test bench simulates vehicle drive system, torque load unit with speedclosed-loop simulates vehicle speed, both are controled at the same time, the torqueload unit providing load torque makes the speed of the test bench to be consistent withthe speed of vehicles.Based on a pure electric vehicle parameters and pure electric car model, the speedof electric vehicle will be calculated with known drive unit torque, and this speed wasgiven to torque load unit with speed closed-loop. Finally, the vehicle motion issimulated. Basis on above theory, test bench simulation model established in matlab software, carried out the simulation of drive motor tests and the simulated the inertia,also, the test bench model simulated start, running, braking of a model of pure electricvehicles. Finaly, test bench with different inertia simulating electric vehicle wasconducted and the motion resistance of test bench was automaticly compensated ontest bench model.According to the above method, pure electric vehicle power system test benchwas builded. Torque load unit of the bench simulated vehicle inertia and vehicleresistance. Then, drive system efficiency test and vehicle inertia simulation was carriedout on the test bench and test data analysis was realized.