一种多模式变频宽输出LLC变换器

针对新能源领域对开关变换器具有宽电压增益范围的要求,提出一种多模式变频宽输出LLC变换器.该变换器原边为全桥结构,副边整流器为两级倍压结构,通过控制副边开关管的导通与截止,具有3种不同的电路模式,其增益比为1:2:4.各种模式对应不同的输出电压等级,采用变频控制方式,变换器可以实现50～430 V的宽输出电压范围.多种...

Multi-mode variable frequency wide output LLC converter

To meet the requirement of wide voltage gain range of switching converter in new energy field,a multi-mode variable frequency wide output LLC converter is proposed. The primary side of the converter is a full bridge structure,and the secondary rectifier is a two-stage voltage doubling structure. By controlling the turn-on and turn off of the secondary switches,the converter has three different circuit modes,and its gain ratio is 1∶ 2∶ 4. Each mode corresponds to different output voltage levels,and the converter can realize a wide output voltage range of 50 V ~ 430 V by using variable frequency control. Multiple mode switching allows the converter to have a narrow switching frequency range( 65 kHz ~ 100 kHz).Through reasonable parameter design,the converter can realize zero voltage switching( ZVS) of the primary switches and zero current switching( ZCS) of the secondary diodes. The new circuit topology reduces the voltage stress on the secondary diodes and secondary capacitors,which is only half the output voltage. Based on theoretical and simulation analysis,a 1. 3 k W experimental prototype was produced.The experimental results show that the converter can achieve a wide output voltage range while ensuring efficiency,and is suitable for wide output applications.