Development Of Isolated Half-bridge AC-DC Converter For Hybird Car Vehicles

In this thesis, the author cooperate with a New Technology Development Co.,Ltd. of Shenzhen to design the3kW on-board charger what used to charge on-boardlithium battery for the company’s hybrid vehicles. Purpose is to solve energy supplyof the hybrid vehicle; without leasing the battery to provide energy to reduce its R&D costs; achieve commercialization, and to create profits for the company. Thesignificance of this project is that on-board charger can charge the battery at homeat night and at the work place in the daily time. When we are unable to find thecharging station, on-board charger can also be used in an emergency charge.The load of on-board charger is lithium batteries. Because of the danger oflithium batteries, we need to control the charging current accuracy. We studied thesingle-cell lithium battery operating mode, and established a lithium battery modelon the basis of operating mode. Compared different topologies for their strengthsand weaknesses, we choose a half-bridge topology based on the actual designrequirements as the main circuit topology and according to the design conditions wecalculated topological parameters.This design uses the isolated driver circuit. Driver chip TC4420outputs6Apeak current and is able to driver IGBT. We use SG3525to control PWM. The thirdchapter analyzes the operating mode of the half-bridge topology and analysis thereason of the IGBT turn-off shocks to provide a theoretical simulation and theexperimental platform. Transformer leakage is introduced into half bridge typecircuit model, and to establish rectifier bridge small signal model.We set up an actual experimental platform in SABER for simulation and gavecurrent conditions10A and2A to simulate the constant current constant voltagecharging mode. The actual output current ripple meets the design requirements.Because the characteristics of recovery of rectifier diode produce peak voltage, theauthors improved an absorption circuit to promote the efficiency of the system.We set up the experimental platform in the conditions of closed-loop testoutput2A. Observing the switch the output voltage waveform and the actual outputcurrent is2.2A. Analyzing the deviation of the output current and discuss the loss ofcomponents.