Research On LLC Resonant Converter Digital Current-sharing Technology

With the problems of environment pollution and energy shortage has become increasingly prominent, the electric car has attracted extensive attention form governments and car manufacturers with its great advantage in technology, environmental protection and energy conservation. At the same time, the technology of the electric vehicle charging also obtained the unceasing development and optimization. Electric vehicle charging power supply usually adopts multiple charging power supply parallel power supply module to realize the high power output, power supply modules in parallel can not only meet the requirement of high power, but also make full use of the model of full control type electronic device. It can also reduce the volume of the power supply, and improve the output efficiency of the power.According to the design requirement of power module, this dissertation uses TMS320F28035 integrated CAN module which produced by TI company as the main control chip, and designs a parallel current-sharing system based on CAN bus. Each power module was controlled through the DSP of the mian control chip. Two decentralized power modules composed the parallel system in parallel, and can realized the digital communication by CAN bus, finally achived the current-sharing of the system. The mian contents of this dissertation contain hardware and software design of the parallel system, and make the prototype. It is verified that the scheme is feasibility and good performance.First of all, this dissertation briefly introduces the research background and significance of the subject、the research status and development trend of parallel current-sharing. On this basis, it analyses the common current-sharing methods.And this dissertation finally selects CAN bus to achieve an average current-sharing.Secondly, it designs the mian circuit、the control circuit(including the auxiliary power supply、drive circui、protection circuit and sampling circuit) with TMS320F28035 as the control core and the hardware design of the parallel system based on the analysis of the mian circuit topology and control strategy. Then, it completed the design of power module main control program and digital current-sharing system control program based on CAN bus, and realized the current-sharing control algorithm.Finally, this dissertation contructed two units of lOkW full bridge three level LLC resonant converter. Through the analysis of the experimental data and image, it verified the validity and feasibility of the syatem.