Research On High Power Density Converter Of Hybrid Electric Vehicle And Control Algorithm

As the continuous development of global economy, the vehicle has graduallybecome an indispensable part in people’s life. It closes the distance among each other,improve the efficiency and the quality of our life. But at the same time, due to theincreasing demand of fossil fuel by conventional vehicles added greatly to airpollution, bringing huge challenge to the oil resource and the ecological environment,looking for a new energy to replace conventional fuel has become an internationalconsensus. New energy automobiles have attracted extensive attention due to its lessdemand for the fossil fuel and less pollution to the environment. Electric vehicle haveprominent advantages in protecting environment, limited by the capacity and energydensity of the battery, its dynamic performance is poor and it has a short range whichmakes it unable to compete with conventional vehicles. High-performance electriccars close to the internal combustion engine car costs expensive which impedes themarketization. As the transitional product from conventional cars to the electrical,hybrid electric vehicle combine the advantages of both, becoming the new model ofautomobile with more practical significance.Aiming at the existing problem of drive system of new energy vehicle, such as:dynamic voltage balance of battery module, the mileage, the power density, servicelife and safety, this paper proposes a hybrid multilevel converter composed ofcascaded H-bridge, matrix converter and medium frequency transformer. H-bridgeparalleled with battery as a module output in cascaded, this circuit is compatible withdifferent kinds of batteries. It will decrease the large-scale batteries in series throughthe independent energy management control. As the energy storage unit, we introducethe dynamic balance algorithm in the charging and discharging process of battery, tokeep the voltage of each battery consistent during the charge and discharge, as a result,it will prolong the service life of battery and at the same time improve the safety.Matrix converter combined with internal combustion engine can achieve outputtorque control and satisfy output requirements of different condition. Both cascaded H-bridge and matrix converter output medium frequency on the primary windings ofMFT, with the secondary windings connected the loads. MFT realize the power flowin system, form the EMS of the proposed converter. Input with medium frequencyvoltage decrease the weight and volume of system effectively, improve the powerdensity of EMS.Based on the research of control strategy in each part, modeled the simulationmodel and verified the validity of the proposed topology and algorithm. Set up theentire hardware platform, verified the balance control of cascaded H-bridge and theEMS algorithm.