Study Of The Control System For Auxiliary Power Unit In Range-extender Electric Vehicle

Because of the enormous challenges brought by energy crisis of traditional vehicles,and the short driving range with electric car, auxiliary power unit(APU) of range-extenderelectric vehicle was researched and control strategy was designed in this paper. Shortdriving range problem of electric vehicles was solved, and fuel consumption was reduced.MATLAB/Simulink was used to study the engine, generator and control strategy fordesigning APU in range-extender electric vehicle.(1) The classical theory about mean value model of engine was studied. The engine’sair, fuel film model and output power model ware established. Speed of engine wascontrolled by PID algorithm. Actual speed was able to follow target speed quickly andsteady-state error was small by optimizating model and adjusting the PID parameters.Mathematical model of permanent magnet synchronous motor was established. Torque ofgenerator was controlled by vector algorithm and PID algorithm. By optimizing the controlalgorithm for permanent magnet synchronous motor, the generator torque could quicklyand accurately follow the target torque. Generator and engine model were handled withrigid connection, which was same as actual physical structure.(2)Based on the APU model, control strategy was designed. After debugging andoptimizing the control strategy, the correctness and feasibility was verified through9NEDC driving cycles. Hardware of APU controller was designed with Motorola MPC563microcontroller, which is the main control chip. The processing circuit about sensors’ inputsignals were designed, and the signal was converted into digital signal by CPU.(3) Finally, control strategy was verified to achieve two control objectives. Firstly,APU output power followed the power request. Secondly, fuel economy targets wasachieved. Through analysis and calculation of test data, control strategy could meet thecontrol objectives. namely, APU output power can quickly and accurately respond to demand power. The fuel consumption per hundred kilometers was only7.6L, which was20%less than conventional vehicles.