Development Of Position Sensorless Start/Generation Control System For Electric Vehicle Range Extenders

In order to improve the endurance of pure electric vehicles,the industry uses range extenders to assist electric vehicles to generate electricity.The range extender start/generation system is mainly composed of a permanent magnet brushless motor and an intelligent controller.This article takes the range extender start/generation integrated machine as the research object,researches the key technology of the range extender start/generation system,and develops a It can be used in the brushless motor start/generation control system on the range extender of electric vehicles,which can provide power output for the whole vehicle when the battery of electric vehicles is insufficient,improve the endurance of electric vehicles,and ensure the high temperature,complex road conditions and other complex environments Work stably under.The main contents are as follows:(1)The initial position of the rotor is determined by the voltage vector method.According to the characteristics of the range-extender system,120° on mode is finally determined to inject the voltage vector to realize the preset position of the rotor,and then the commutation is started from the next commutation position.(2)Determine the starting strategy and control algorithm of position sensorless brushless motor.The internal combustion engine of the range extender will have a relatively large resistance in the compression process,so the brushless motor needs to overcome the resistance of the internal combustion engine in the starting process.According to the characteristics of the system,the starting control algorithm is finally determined and the internal combustion engine is dragged to the ignition speed smoothly.(3)Determine the generation control strategy of sensorless brushless motor and its simulation analysis.The back electromotive force generated by brushless motor in the generating state is far more than the voltage withstand value of the on-board battery.The generation control algorithm determined in this paper ensures the stable voltage output in the wide speed range and the generation control algorithm is simulated and analyzed.(4)The rotor position detection method is proposed and verified by simulation.In the process of brushless motor running,commutation operation should be carried out according to the rotor position to ensure the stable running of the system.In this paper,based on the back electromotive force zero crossing,the line back electromotive force zero crossing method is proposed to detect the rotor position information and the simulation analysis is made.(5)Design and manufacture of range extender startup/generation system hardware,design range extender startup/generation system control software.Firstly,the hardware schematic diagram design,PCB drawing,device selection and other hardware design are completed in the limited space.It also follows the design idea of high cohesion and low coupling to write the control software to make the system run stably and efficiently.(6)The towing test platform is designed,and the software and hardware of the integrated control system of range extender start/power generation are debugged.