基于负载匹配的三相交错并联LLC谐振变换器变模式控制策略
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摘要
针对三相交错并联LLC谐振变换器的负载工况,提出一种基于负载匹配的变模式控制策略。当工作在额定负载时,采用脉冲频率调制(PFM)控制方法使其发挥最大效率;当工作在轻载时,设计对称脉宽调制(PWM)控制策略,利用电压增益曲线中负载独立点的特性设计开关频率,既实现了软开关,也限制了开关频率的增大。深入研究对称PWM控制下的工作原理与增益特性,进一步对变换器的线性控制区和非线性控制区展开分析。当工作在极轻载与空载状态时,采用Burst控制方法实现对输出电压的有效控制。此外,对不同控制策略之间切换点的选择进行了详细分析与优化设计,准确可靠地实现了变模式控制。最后,基于碳化硅器件研制变换器实验样机,验证对变换器进行性能分析和变模式控制策略的正确性与合理性。
A variable mode control strategy is proposed for a three-phase staggered-parallel LLC resonant converter,in which the load matching for load conditions is considered. In the case of rated load conditions,the PFM(Pulse Frequency Modulation) control method is used to maximize its performance efficiency. On the light load condition,the symmetrical PWM(Pulse Width Modulation) control strategy is designed,and the switching frequency that considers the characteristics of the load-independent point in the voltage gain curve is designed,which not only realizes soft switching,but also restricts the increase of switching frequency. The working principle and gain characteristics of symmetrical PWM control are studied,and the linear and nonlinear control zone of the converter are analyzed in detail. On the extremely light load and no load conditions,the Burst control method is employed to enable an effective control of the output voltage. Besides,the selection of switching points between different control strategies is analyzed and designed in detail,and the variable mode control strategy is realized accurately and reliably. The converter experimental prototype is developed based on SiC devices to verify the effectiveness and rationality of the performance analysis and variable mode control strategy of the converter.
A variable mode control strategy is proposed for a three-phase staggered-parallel LLC resonant converter,in which the load matching for load conditions is considered. In the case of rated load conditions,the PFM(Pulse Frequency Modulation) control method is used to maximize its performance efficiency. On the light load condition,the symmetrical PWM(Pulse Width Modulation) control strategy is designed,and the switching frequency that considers the characteristics of the load-independent point in the voltage gain curve is designed,which not only realizes soft switching,but also restricts the increase of switching frequency. The working principle and gain characteristics of symmetrical PWM control are studied,and the linear and nonlinear control zone of the converter are analyzed in detail. On the extremely light load and no load conditions,the Burst control method is employed to enable an effective control of the output voltage. Besides,the selection of switching points between different control strategies is analyzed and designed in detail,and the variable mode control strategy is realized accurately and reliably. The converter experimental prototype is developed based on SiC devices to verify the effectiveness and rationality of the performance analysis and variable mode control strategy of the converter.
引文
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[13] 刘闯,齐瑞鹏,刘海军,等.一种减小三相级联型PET各中间直流侧电容的方法[J].电力自动化设备,2017,37(11):46-53.LIU Chuang,QI Ruipeng,LIU Haijun,et al.Method of decreasing intermediate DC-link capacitors for three-phase cascaded power electronics transformers[J].Electric Power Automation Equipment,2017,37(11):46-53.
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[15] JEONG Y,MOON G W,KIM J K.Analysis on half-bridge LLC resonant converter by using variable inductance for high efficiency and power density server power supply[C]//Applied Power Electronics Conference & Exposition.Tampa,Florida,USA:IEEE,2017:170-177.
[2] 刘闯,徐鑫哲,刘海洋,等.基于电流平衡单元的输入并联输出并联型LLC谐振变换器模块[J].电工技术学报,2016,31(21):159-167.LIU Chuang,XU Xinzhe,LIU Haiyang,et al.Current balancing cell based IPOP LLC resonant converter modules[J].Transactions of China Electrotechnical Society,2016,31(21):159-167.
[3] 潘海燕,贺超,蒋友明,等.高效的LLC谐振变换器变模式控制策略[J].电力自动化设备,2015,35(1):71-78.PAN Haiyan,HE Chao,JIANG Youming,et al.Efficient variant mode control of LLC resonant converter[J].Electric Power Automation Equipment,2015,35(1):71-78.
[4] 周立身.宽输出电压的半桥型LLC谐振变换器设计[J].电力电子技术,2016,50(6):71-73.ZHOU Lishen.Design of half-bridge LLC resonant converter with wide output voltage[J].Power Electronics,2016,50(6):71-73.
[5] HAN H G,CHOI Y J,CHOI S Y,et al.A high efficiency LLC resonant converter with wide ranged output voltage using adaptive turn ratio scheme for a Li-ion battery charger[C]//Vehicle Power & Propulsion Conference.Hangzhou,China:IEEE,2016:1-6.
[6] LEE W,CHOI S,KIM C,et al.A new PWM-controlled quasi resonant converter for a high efficiency PDP sustaining power module[J].IEEE Transactions on Power Electronics,2008,23(4):1782-1790.
[7] GU Y,HANG L,LU Z.A flexible converter with two selectable topologies[J].IEEE Transactions on Industrial Electronics,2009,56(12):4854-4861.
[8] 王皓,朱金大,侯凯,等.基于混合控制式交错并联LLC谐振变换器的充电模块研制[J].电力系统自动化,2017,41(7):108-113.WANG Hao,ZHU Jinda,HOU Kai,et al.Development of charging module based on interleaving paralleled LLC resonant converter with hybrid control[J].Automation of Electric Power Systems,2017,41(7):108-113.
[9] PARK H P,JUNG J H.PWM and PFM hybrid control method for LLC resonant converters in high switching frequency operation[J].IEEE Transactions on Industrial Electronics,2016,64(1):253-263.
[10] CHEN J,SATO T,YANO K,et al.An average input current sensing method of LLC resonant converters for automatic Burst mode control[J].IEEE Transactions on Power Electronics,2017,32(4):3263-3272.
[11] 赵豫京,李建兵,范卿,等.半桥LLC谐振倍压变换器的混合控制策略[J].信息工程大学学报,2016,17(4):410-413.ZHAO Yujing,LI Jianbing,FAN Qing,et al.Hybrid control strategy of half-bridge LLC voltage-multiplying resonant converter[J].Journal of Information Engineering University,2016,17(4):410-413.
[12] SHEN Y,ZHAO W,CHEN Z,et al.Full-bridge LLC resonant converter with series-parallel connected transformers for electric vehicle on-board charger[J].IEEE Access,2018(6):13490-13500.
[13] 刘闯,齐瑞鹏,刘海军,等.一种减小三相级联型PET各中间直流侧电容的方法[J].电力自动化设备,2017,37(11):46-53.LIU Chuang,QI Ruipeng,LIU Haijun,et al.Method of decreasing intermediate DC-link capacitors for three-phase cascaded power electronics transformers[J].Electric Power Automation Equipment,2017,37(11):46-53.
[14] ORIETTI E,MATTAVELLI P,SPIAZZI G,et al.Current sharing in three-phase LLC interleaved resonant converter[C]//Energy Conversion Congress & Exposition.San Jose,California,USA:IEEE,2009:1145-1152.
[15] JEONG Y,MOON G W,KIM J K.Analysis on half-bridge LLC resonant converter by using variable inductance for high efficiency and power density server power supply[C]//Applied Power Electronics Conference & Exposition.Tampa,Florida,USA:IEEE,2017:170-177.