针对全桥 LLC 谐振变换器最常采用的变频-移相法在传统比例积分(PI)控制下动态超调较大的问题,提出一种 PI-滑模混合控制方法.该控制方法结合了PI控制与滑模控制的优点,在输出电压距离参考电压较远时采用滑模控制,输出电压接近参考电压时切换为 PI 控制,通过模糊控制完成两者的平滑过渡.详细分析了全桥 LLC 谐振变换器在变频模式和移相模式下的工作原理以及工作特性,给出混合控制方法的具体实现方案.为了验证所提方法的可行性,搭建仿真模型进行PI控制方法、滑模控制方法与PI-滑模混合控制方法三种方法的性能对比分析,并制作一台额定功率 2 kW的样机,试验结果表明,提出的PI-滑模混合控制方法可以显著降低系统的动态响应超调,同时消除稳态阶段的抖振问题,体现出良好的控制效果.
Full-bridge LLC Resonant Converter Based on Hybrid Control
Aiming at the problem of large dynamic overshoot under traditional proportional integral(PI)control,the most commonly used frequency conversion-phase shift method for full-bridge LLC resonant converters,a PI-sliding mode hybrid control method is proposed.This control method combines the advantages of PI control and sliding mode control,using sliding mode control when the output voltage is far from the reference voltage,switching to PI control when the output voltage is close to the reference voltage,and completing the smooth transition between the two through fuzzy control.The working principle and working characteristics of the full-bridge LLC resonant converter in frequency conversion mode and phase shift mode are analyzed in detail,and the specific implementation scheme of the hybrid control method is given.In order to verify the feasibility of the proposed method,the simulation model is built and the performance comparison analysis of PI control method,sliding mode control method and PI-sliding mode hybrid control method is carried out.And made a prototype with a rated power of 2 kW.The experimental results indicate that the proposed PI-sliding mode hybrid control method can remarkably lower the system's dynamic response overshoot,and eliminate the chattering issue in the steady state stage,demonstrating a good control performance.
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