【摘要】 LLC谐振变换器能够实现全负载范围的初级零电压开关(ZVS)和次级零电流开关(ZCS),因此得到关注。全桥LLC谐振电路可以通过改变初级开关管驱动脉冲频率调制(PFM)方法,调节LLC谐振腔的增益进行闭环控制,保证输出电压在输入电压变化大、不同负载条件下的输出稳定。LLC谐振增益曲线会随负载减轻而调节特性变差,单一PFM调节无法应对。研究集PFM、脉宽调制(PWM)和间歇工作模式(Burst模式)的混合控制方案,解决变换器从空载到满载不同工作条件下的控制方式,并在发生短路故障时变换器迅速保护。此处采用HPM6300系列芯片完成LLC数字控制和保护功能,设计系统的实验装置并编写应用软件。经过整机测试,实验结果表明所采用方案的有效性,并达到设计目标。更多还原

【Abstract】 LLC resonant converters have gained attention for their ability to implement primary zero voltage switches(ZVS) and secondary zero current switches(ZCS) over the full load range.The full-bridge LLC resonant circuit can adjust the gain of the LLC resonator for closed-loop control by changing the primary switching tube drive pulse frequency modulation(PFM) method,so as to ensure that the output of the output voltage is stable under great change of input voltage and different load conditions.The LLC resonant gain curve will deteriorate with load reduction and a single PFM adjustment can not cope with it.The hybrid control scheme of PFM,pulse width modulation(PWM) and Burst mode is studied to solve the control mode of the converter under different working conditions from no-load to full-load and to protect the converter quickly when short circuit fault occurs.HPM6300 series chip is used to complete the LLC digital control and protection function,the experimental device of the system is design and the application software is writen.Through the whole machine test,the experimental results show that the scheme is effective and meets the design objectives.更多还原