Research And Implementation Of High Power Water Cooled Intelligent Range Extender For Electric Vehicle

Range extender is an auxiliary power generation system for electric vehicles,which can increase the driving range of electric vehicles on a single charge,reduce the number of on-board batteries,reduce the cost of electric vehicles,and achieve a smooth transition from fuel vehicles to pure electric vehicles.Electric vehicle range extender requires small volume,light weight,high efficiency,so the core part of the range extender-motor uses brushless DC motor.The range extender of high power electric vehicle using brushless DC motor as starting/generating motor is studied.The working principle of the brushless DC motor is analyzed.In order to detect the rotor position of the brushless DC motor reliably and accurately,a zero-crossing detection method of backpotential based on terminal voltage is analyzed.This method can make the brushless DC motor carry out accurate commutation and ensure the smooth operation of the brushless DC motor.When the range extender starts,the brushless DC motor first operates in electric mode to start the engine.In order to improve the starting stability of the range extender,the torque pulsation of the brushless DC motor under different types of PWM modulation is studied.Finally,the PWM modulation mode is selected to improve the electromagnetic torque pulsation of the brushless DC motor,so that the brushless DC motor can start the engine smoothly.In order to make the brushless DC motor in the range extender have excellent dynamic characteristics,the principle of direct torque control of brushless DC motor is studied,and the direct torque control technology is introduced into the power generation state and the starting/generation conversion process of brushless DC motor.Through the experiment,the power generation results of brushless DC motor using direct torque control are compared with those using dual-PI control range expander.The results show that the brushless DC motor using direct torque control technology can significantly improve the power generation efficiency.In order to solve the problem of fast heat dissipation of the range extender in limited space,the circuit topology of the intelligent control system of the range extender is studied.The inverter and the rectifier are respectively assembled on different metal shell baseboards.The structure optimization of the water-cooled range extender is studied.The hardware and software design and implementation process of 7k W/72 V range extender control system are introduced.