基于GaN器件与磁集成技术的车载充电机实验平台研究

Research on onboard charger experimental platform based on GaN devices and magnetic integration technology

随着新能源汽车的普及,对车载充电机的要求越来越高。为了有效提升整机效率和功率密度,将GaN器件与磁集成技术应用于车载充电机,进行了实验平台研究。基于GaN器件设计了两级式车载充电机拓扑结构与外围电路,通过制作磁集成平面变压器,优化了CLLC变换器,完成了整机控制程序设计及2kW车载充电机实验样机搭建,并对样机进行了实验测试与波形分析。实验结果表明,实验样机具有良好的稳态特性与动态特性,整机功率因数在0.98以上,满载峰值效率达到95.22%。该平台能够帮助学生加深对电力电子技术的认识,掌握新型电力电子器件的特性及应用,锻炼实践操作能力,提高相关课程的教学质量。

[Objective]With the development and increasing popularity of electric vehicles,portable onboard charger technology based on household power supply systems is receiving growing attention.Achieving high power factor,high efficiency,miniaturization,and high power density in onboard chargers is a critical challenge.At present,traditional Si metaloxide–semiconductor field-effect transistors(MOSFETs)are used as the main power tubes in onboard chargers,and magnetic elements are usually independent wire-wound magnetic elements,which limit the improvement of efficiency and power density.[Methods]This paper presents the structural design of a two-stage vehicle charger that utilizes a totem pole bridgeless PFC converter and a CLLC resonant converter.The totem pole PFC converter operates in continuous conduction mode,leveraging the excellent reverse recovery characteristics of GaN devices.Additionally,the fast switching speed of GaN devices increases the overall operating frequency,thereby reducing component size.Simultaneously,planar magnetic integration technology is utilized to design and produce a magnetic integrated planar transformer with controllable leakage inductance.This transformer utilizes the leakage inductance of its primary and secondary edges to replace the resonant inductance of the primary and secondary edges of the CLLC converter,thereby reducing the number of components and the size of the CLLC converter.This paper presents the design of the peripheral circuits and controller resources required for the experimental prototype of an onboard charger.A soft-start strategy is employed to achieve multiple control processes,from startup to stable operation.The overall system logic was designed,and a 2-kW onboard charger prototype was constructed.During the prototype start-up,we validated the effectiveness of the system's soft-start strategy by observing the recovery of the bus voltage and current overshoot when the PFC converter transitions from a no-load to a load state.The study examined the steady-state waveforms of the PFC converter at various input voltage frequencies and compared the critical experimental waveforms of the CLLC resonant converter at three output voltage levels to verify that the designed onboard charger meets the design specifications.Finally,the onboard charger's ability to regulate sudden load variations and its efficiency under constant voltage and constant current modes were validated.[Results]The experimental test results show that:1)GaN devices significantly enhance the power level of the totem pole bridgeless PFC converter,improving the efficiency and power density of the vehicle charger;2)the designed controllable leakage magnetic integrated planar transformer meets the design requirements;3)the designed vehicle charging system demonstrates good steady-state characteristics and dynamic regulation capability,with the performance of the entire machine meeting the design specifications.[Conclusions]This experimental platform helps students better understand the working principles,characteristics and applications of power electronic devices.It provides diversified and practical hands-on learning opportunities,integrating knowledge into teaching,injects new impetus and vitality into the school's teaching quality and ability,and cultivates excellent electrical engineering talents with all-round development.