降低整流管电压应力的宽输入LLC参数优化方法

A Parametric Optimization Method for Reducing Voltage Stress of Rectifier Tube in Wide Input LLC

为了提高宽电压范围输入LLC谐振变换器的可靠性,针对宽输入LLC谐振变换器在寄生参数的影响下整流管电压产生高频振荡导致电压应力过大的问题,分状态建立等效模型和状态方程。根据整流管电压应力随工作频率的变化规律,分析应力最大区域并提出能降低整流管电压应力的参数优化设计方法。在该方法下,整个工作区间在避开应力最大区域的同时保证了增益宽度。搭建2.5倍输入范围的600 W全桥LLC平台,开展实验验证。实验结果表明,相比传统的宽电压范围输入LLC参数设计方法,该方法显著降低了工作范围内的整流管最大电压应力值,提高了电路的安全稳定性。

In order to improve the reliability of the wide voltage range input LLC resonant converter,the equivalent model and state equation are established to solve the problem of excessive voltage stress caused by the high frequency oscillation of rectifier tube’s voltage under the influence of parasitic parameters in the wide input LLC resonant converter.According to the variation law of rectifier tube’s voltage stress with working frequency,the maximum stress region is analyzed and a parametric optimization design method to reduce voltage stress of rectifier tube is proposed.In this method,the gain width is guaranteed while avoiding the maximum stress region in the whole working zone.A 600 W full-bridge LLC platform with 2.5 times input range is built to carry out experimental verification.The experimental results show that,compared with the traditional wide voltage range input LLC parametric design method,the proposed method significantly reduces the maximum voltage stress of the rectifier tube in the operating range,and improves the safety and stability of the circuit.