Research On Three-leve ZVS Half-bridge Charger And Its Parallel Current Sharing Technology

With the World environment and Energy problem going from bad to worse, large energy consumption and badly environment pollution that the traditional internal combustion engine vehicle causes have raised concerns around the world.The development of new energy vehicles has attracted the world-wide attention. As a new energy automobile charging device, the electric vehicle charger plays an important role in promoting the development of new energy vehicles. To develop a high-power, high safety and reliability and high efficiency of electric vehicle charger has a very vital significance. In addition, to realize the fast charging of the electric vehicles, the Electric Vehicle Charging Station generally uses a distributed power system which is constituted by a few paralleled chargers to improve the capacity of the Electric Vehicle Charging Station. Due to the production technology differences and the device features differences, the current of paralleled chargers is uneven during the runtime. So research on parallel current sharing technique of electric vehicle chargers is needed.The gaol of this paper is to develop a half-bridge three-level ZVS charger and research the parallel-current-sharing scheme of multiple chargers. This article firstly introduced a topology structure of a half-bridge three-level ZVS charger and the working principle of a half-bridge three-level ZVS dc converter, and made a parameter calculation and selection for the power device of the charger’s power circuit on this basis. And then it designed a control circuit with a core of TMS320F2812 DSP and a protection circuit with a core of CPLD, which plays a role of a hardware protector when inputting overvoltage, outputting overvoltage and overcurrent, etc. CAN bus is the multiple master bus and has the high anti-interference ability. With these two advantages, we finally designed a CAN bus based master-slave control method to achieve the parallel current sharing between multiple chargers. This method can also realize constant voltage charging control.In this paper, the author developed a half-bridge three-level ZVS charger whose control frequency is 100 KHZ, output power is 7.5KW, and efficiency is 93%. the disign of the half bridge three level ZVS charger has been verified to be correct through the debugging and the experiment on the main power circuit and the control circuit.The simulation for the parallel current sharing of multiple chargers from MATLAB/Simulink and the experimental results verified the correctness of the theoretical analysis and design method.