Research On Braking Energy Recovery Control System Of Electric Vehicle

The world is facing double challenges of energy shortage and environmental pollution,pure electric vehicles because of zero pollution,low energy consumption,has become one of the direction of the development of the car,but the battery technology is temporarily unable to have a big breakthrough,in pure electric vehicles are generally inadequate driving range,battery life short problem.The super capacitor has a good complementary with the lithium battery,with the composition of composite power system,can not only extend the driving range,in addition,the super capacitor of braking energy recovery can further extend the driving range,extend battery life and reduce mechanical brake parts loss,therefore,recovery of electric vehicle braking energy control the system of double power system research has important significance.In this paper,the dual energy system is used as the energy source of the electric vehicle,and the brushless DC motor is used as the driving motor of the electric vehicle.Firstly,the lithium battery is chosen as the main energy source of the energy system through the comparison of the lithium battery and the storage battery.Then,the structure of the lithium battery and the super capacitor is analyzed,and the auxiliary power source single converter parallel mode is selected.Through the introduction and comparison of several types of bi-directional DC/DC converter,the paper selects and uses a two-phase interleaved bi-directional DC/DC converter as the driving circuit of the supercapacitor.The circuit structure and working principle of the brushless DC motor is introduced,the three-phase bridge inverter circuit used as motor drive circuit,the selection is relatively simple and reliable 22 conduction mode through the switch of the guide way.Then,the 4 states of the electric vehicle are analyzed and compared,such as the normal running state,start up,climbing state,the state of braking energy recovery,and the state of super capacitor energy storage.According to the electric state and the feedback state of the brushless DC motor,the motor is driven by the double closed loop control.The state of charge and discharge of the capacitor is analyzed quantitatively,and the PI controller is used to control the two interleaved bi-directional DC/DC converter.Finally,the DC brushless motor/controller and dual power module are built in ADVISOR,and the simulation of the vehicle is done in the urban cycle and the suburbs.