一种三相交错并联LLC谐振变换器轻载控制策略
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摘要
针对LLC谐振变换器轻载及空载时,开关频率在高频段变化范围大,造成变换器中部分元件的磁集成设计困难、易引起电压失控等问题,此处基于三相交错并联LLC谐振变换器设计对称脉宽调制(PWM)控制方法。通过设计软开关的实现条件,将变换器的运行模式分为软开关和硬开关两种状态,并分别对其工作原理与运行模态进行深入分析,得到具有单调性和非单调性的增益曲线,从而找到变换器最佳运行区间,实现变换器在轻载时既能工作在软开关状态,又能有效控制输出电压。基于SiC器件研制LLC谐振变换器实验样机,验证理论分析的正确性及方案的可行性。
LLC resonant converter switching frequency has a large range of changes in the high frequency when it is under light load and no load, this has caused difficulties in the design of magnetic integration of some components in the converter and the risk of voltage out of control.A symmetrical pulse width modulation(PWM) control method based on a three-phase interleaved parallel LLC resonant converter is designed.By designing the conditions of soft switching,the operating mode of the converter can be divided into two states, soft-switching and hard switching.The working principle and gain characteristics of the converter are analyzed in-depth.The gain curve with monotony and non-monotonicity characteristics are obtained to find the best operating range of the converter.The converter can work in the soft-switching state and effectively control the output voltage under light load.The converter experimental prototype is developed based on SiC devices to verify the correctness and rationality of the theoretical analysis.
LLC resonant converter switching frequency has a large range of changes in the high frequency when it is under light load and no load, this has caused difficulties in the design of magnetic integration of some components in the converter and the risk of voltage out of control.A symmetrical pulse width modulation(PWM) control method based on a three-phase interleaved parallel LLC resonant converter is designed.By designing the conditions of soft switching,the operating mode of the converter can be divided into two states, soft-switching and hard switching.The working principle and gain characteristics of the converter are analyzed in-depth.The gain curve with monotony and non-monotonicity characteristics are obtained to find the best operating range of the converter.The converter can work in the soft-switching state and effectively control the output voltage under light load.The converter experimental prototype is developed based on SiC devices to verify the correctness and rationality of the theoretical analysis.
引文
[1]金峰,刘福鑫,阮新波.采用模块化结构的多相多电平LLC谐振变换器[J].中国电机工程学报,2015,35(17):4486-4493.
[2]孙孝峰,申彦峰,李午英,等.交错并联双向Buck/Boost集成LLC谐振型三端口直流变换器[J].电工技术学报,2016,31(14):165-175.
[3] T Mishima, H Mizutani, M Nakaoka.A Sensitivity-improved PFM LLC Resonant Full-bridge DC/DC Coverter With LC Antiresonant Circuitry[J].IEEE Trans. on Power Electronics,2016,32(1):310-324.
[4]胡海兵,王万宝,孙文进,等.LLC谐振变换器效率优化设计[J].中国电机工程学报,2013,33(18):48-56.
[5]刘玮,牛鸣德,夏永涛.半桥LLC谐振变换器的特性分析[J].现代机械,2011,37(5):30-32.
[6] H P Park,J H Jung.PWM and PFM Hybrid Control Method for LLC Resonant Converters in High Switching Frequency Operation[J]. IEEE Trans. on Industrial Electronics,2016,64(1):253-263.
[7] Lee I, Moon G.The k-Q Analysis for an LLC Series Resonant Converter[J]. IEEE Trans. on Power Electronics,2014,29(1):13-16.
[2]孙孝峰,申彦峰,李午英,等.交错并联双向Buck/Boost集成LLC谐振型三端口直流变换器[J].电工技术学报,2016,31(14):165-175.
[3] T Mishima, H Mizutani, M Nakaoka.A Sensitivity-improved PFM LLC Resonant Full-bridge DC/DC Coverter With LC Antiresonant Circuitry[J].IEEE Trans. on Power Electronics,2016,32(1):310-324.
[4]胡海兵,王万宝,孙文进,等.LLC谐振变换器效率优化设计[J].中国电机工程学报,2013,33(18):48-56.
[5]刘玮,牛鸣德,夏永涛.半桥LLC谐振变换器的特性分析[J].现代机械,2011,37(5):30-32.
[6] H P Park,J H Jung.PWM and PFM Hybrid Control Method for LLC Resonant Converters in High Switching Frequency Operation[J]. IEEE Trans. on Industrial Electronics,2016,64(1):253-263.
[7] Lee I, Moon G.The k-Q Analysis for an LLC Series Resonant Converter[J]. IEEE Trans. on Power Electronics,2014,29(1):13-16.