The Research On Vehicle Control Unit For Extended Range Electric Vehicle

With the improvement of people’s production and living standards, as animportant transport vehicle’s quantity is growing rapidly. Although vehicle provideslots of convenience, it accelerates the consumption of petroleum resources, whichaggravates the situation of petroleum resource consumption and environmentpollution. To meet human needs and reduce petroleum resource consumption,researchers begin to develop new energy vehicles. Electric vehicle as a clean vehiclewith zero-pollution and zero-emission is the perfact solution. But its promotion isblocked because the battery technology has not got breakthrough progress yet,remaining high-cost and long charging time problems. Range extended electricvehicle as an ideal solution between conventional vehicle and electric vehicle has gotfast development under this circumstance.The core technologies of range extended electric vehicle include batterytechnology, energy management, motor control system and so on. As to these coretechnologies, a design of vehicle control unit and an energy management strategy areproposed in this paper. The design of vehicle control unit consists of overall framwork,modular circuit design, PCB design and circuit test. A detailed design project basedon the MC9S12XEP100micro-controller is also proposed, which has passed thefunctionality and stability test.The energy management strategy of range extended electric vehicle containsmany aspects of its complex structure. To achieve battery protection, a self-adaptiveand variable structure fuzzy control strategy is proposed to limit the charging anddischarging frequency and current. The fuzzy controller’s inputs are SOC(State ofCapacity) and driving motor power demand and output is power of range extender.And then the design methods of self-adaptive and variable structure control arefurther added to the fuzzy controller. The self-adaptive method depending on thechange rate of SOC is presented to limit the charging or discharging current. Based onthe battery state the variable structure method with different control rules is adoptedto limit the frequency, and divide the SOC battery states into charging state anddischarging state. The battery protection is achieved with those two aspects at last.Finally, simulation results via CRUISE are in accordance with that of rangeextender bench test.They both meet the design demandsand make a good preparationfor vehicle test.