中文摘要：

为了拓展新能源并网的输入电压范围,提出一种全桥LLC（FBLLC）和半桥LLC（HBLLC）相结合的变拓扑电路.当输入电压低,采用FBLLC模态;当输入电压高,采用HBLLC模态.通过由数字信号处理器（DSP）进行全数字控制,电路随着输入电压的变化在HBLLC和FBLLC之间切换.这种变拓扑电路完全不增加额外器件,单纯依靠软件控制,控制简单,在拓扑切换上采用一种新的控制策略来尽可能优化效率.与传统LLC对比,分析和实验表明,在相同条件下,变拓扑LLC使输入电压范围能够拓展1倍.通过一个最大和最小输入电压比为4的对比试验,分别采用变拓扑LLC和传统LLC,结果表明：采用变拓扑电路,其整体效率能提升约3%.该拓扑适合应用于超宽输入电压范围的场合,如风力、光伏发电等.

英文摘要：

A novel variable LLC was presented on the purpose of expending the grid input voltage range in new energy.The variable LLC varies between full bridge LLC（FBLLC）and half bridge LLC（HBLLC） with the step of input voltage.The topology is FBLLC when the input voltage is low;the topology will change to HBLLC automatically by digital signal processor（DSP）controller while the input voltage is high.The circuit does not add any additional component and with simple software control.A new topology switching strategy was also presented to optimize efficiency.Analysis and experimental result showed that the input voltage was expended to twice to that of the traditional LLC.The two topologies（variable LLC and traditional LLC）used in the occasion that the maximum to minimum input voltage ratio is 4respectively. Experimental result showed that the total efficiency increased by about 3% by using the variable topology.The topology is suitable for applications with ultra-wide input voltage range such as solar and wind energy.