Research On Electric Vehicle Chager Based On Series-parallel Hybrid-type Structure

Electric vehicles is one of the most effective way to ease energy shortage and airpollution with less emissions, low noise, high efficiency and low maintenance and runningcosts. We must develop supporting charging power supply system for it is an essentialsubsystem to promote the spread in a large range of electric vehicles. Multi-moduleseries-parallel hybrid-type structure of the charging power supply system is meaningful toenlarge the charge capacity, improve system reliability, take redundant configuration andmodular design, reduce the system maintenance costs and size. However, series-parallelhybrid-type charger needs to take current-sharing and voltage-sharing measures to ensurethe power-sharing between the modules, avoiding overcurrent or overvoltage situation. Inthis paper, a Lithium-ion battery charger based on an improved phase-shifted full-bridgeZVS DC/DC converter and series-parallel hybrid-type technology is designed, whoseoutput voltage is160V, and output current is80A.Firstly, the basic working principle of an improved phase-shifted full bridge ZVSDC/DC converter, including the condition of the lead and lag bridge arm to achievezero-voltage switching, the causes of duty cycle loss, the role of and location in series ofthe DC isolation capacitor, is analyzed. Then, main circuit simulation analysis concludingthe clamping diode rectifier diodes is made， clamping diode rectifier diodes can suppressthe peak voltage effectively and reduce the loss caused by diode reverse recovery at thesame time.Secondly, the main circuit parameters is designed, including the phase-shiftedfull-bridge pulse circuit, MOSFET drive circuit, protection circuit, and choose powerdevices. After that, the basic working principle of droop current sharing method and activecurrent sharing technique is introduced. Simulation analysis of active current sharingschemes is made. Based the working principle and simulation analysis, advantages anddisadvantages of this schemes is compared, the control strategy using outter loop controlleradding with basic average current control is adopted.Again, a phase-shifted full-bridge ZVS DC/DC converter small-signal modeling iscompleted. Current-sharing controllers, voltage-sharing controllers, detection circuit, A/D sampling module, D/A converter module, control system software and CAN buscommunication are devised. And, the main circuit parameters design, the phase-shiftedfull-bridge ZVS DC/DC converter small-signal modeling, current-sharing controllers andvoltage-sharing controllers design are verified well, as showed in the simulation.Lastly, experiments results, including experimental waveforms and measurement dataof the two modules in parallel, the two modules in series and four-module in series-parallelhybrid-type operation, are showed which verifies the theoretical analysis and designs.