| In order to solve the energy crisis and environmental pollution caused by traditional fuel vehicles,electric vehicle(EV)has become the development trend of the automotive industry and the key technology of EV has become a worldwide research topic.As one type of EV,small EV’s research is relatively weak in the entire EV field.Compared with ordinary EV,small EV has the advantages of simple structure and low price.The power and economy of vehicle are determined by the performance of the drive system,which as a key technology has become a research hotspot.Based on this,the paper follows drive system of small EV as the research object and has depth analysis to structure and parameter design of the drive system,energy control strategy and experiment.Based on the depth study and analysis of the characteristics of common drive systems,a novel drive system and its control method are proposed,which can realize the efficient use of energy and brake energy regeneration of small EV.The designed drive system includes hybrid power source composed of battery banks and UC banks,bi-directional DC/DC power converter(BDPC),H-bridge inverter and drive motor.A novel technology of series-parallel switchover of UC banks is adopted in hybrid power source to achieve variable voltage power supply.On the basis of theoretical analysis and design of the components of the drive system,the parameters of the whole vehicle and the components of the drive system are matched,and the mathematical model and simulation model based on Matlab/Simulink of battery-UC hybrid power source,BDPC,H-bridge inverter,drive motor and the overall drive system are established.In order to ensure the efficient flow of energy in the novel drive system,an energy flow control strategy of real-time switching in multiple modes is proposed,which includes four working modes: forward-buck provide energy,forward-boost provide energy,reverse-buck recovery energy,reverse-buck recovery energy.Increment PID controller and differential forward PID controller are designed to control the system bus voltage and motor current,and the controller parameters are optimized.In order to justify the correctness and effectiveness of the novel drive system and its control strategy,while establishing a system model based on Matlab/Simulink and conducting simulation studies,a small experimental platform was built in the laboratory and the principle experiments were carried out.The results show that the novel drive system can improve the efficiency of energy utilization and brake energy regeneration,and efficient flow of energy is achieved in the drive system.The novel drive system and its control method are also suitable for pure electric vehicles(PEV),hybrid electric vehicles(HEV)and extended-range electric vehicle(EREV),which has great advantages compared to traditional drive systems. |
