【作者】 宋伟；

【导师】 熊炫； 童乔凌；

【作者基本信息】 华中科技大学 ， 集成电路工程（专业学位）， 2024， 硕士

【摘要】 超高频功率变换器通过大幅提升开关频率,可减小电路对电感、电容等无源储能元件的需求,从而显著提高功率变换器的功率密度。为维持高效率,现有研究中的超高频功率变换器大多工作在断续模式,以保证功率管实现软开关。这导致输出电压中包含低频的控制纹波,牺牲了超高频功率变换器原本低纹波的优势。针对上述问题,有必要开展超高频功率变换器的新型控制方法研究,实现低输出电压纹波的目标,同时兼顾效率和负载范围。本文在对超高频DC-DC变换器的基本原理和设计方法开展研究的基础上,通过描述函数与阻抗等效法构建了隔离型Class-E变换器的简化等效模型,并基于此模型提出了临界导通调频控制方法。该方法通过调整功率管的驱动频率来改变输出功率的大小,可使得功率变换器连续工作以降低输出电压纹波,并可通过实时调整导通时间至临界值来保证功率管的软开关。随后通过仿真验证与板级实验证明了临界导通调频控制方法的有效性,相比传统的ON-OFF控制方法在电压纹波、效率等方面均有显著优势。为进一步发挥临界导通调频控制方法的优势,提高集成度,并解决板级实验中数字实现时的极限环振荡问题,实现电压纹波的最优化,本文设计了一款适用于超高频功率变换器的驱动与控制芯片。该款芯片采用华虹宏力180 nm BCD工艺设计并流片,可通过模拟电路实现临界导通调频控制。芯片的系统级测试结果表明,在模拟实现的临界导通调频控制方法下,输出电压纹波最低可至34 m V,相比数字实现方式明显消除了极限环振荡;相较传统的ON-OFF控制方式更是可将电压纹波降低约80%,并同时将效率提升约2%。更多还原

【Abstract】 By significantly increasing the switching frequency,the very high frequency(VHF)power converter can reduce the demand for passive energy storage components such as inductors and capacitors,so as to greatly improve the power density of the converter.In order to maintain high efficiency,most existing research on VHF power converters operates in discontinuous mode to ensure soft switching of the power switch.This results in low-frequency control ripple in the output voltage,sacrificing the original advantage of low ripple in VHF power converters.To address the above issues,it is necessary to conduct research on new control method for VHF power converters to achieve the goal of low output voltage ripple,while also considering efficiency and load range simultaneously.Building upon research into the basic principles and design methods of VHF DC-DC converters,this thesis establishes a simplified equivalent model of isolated Class-E converter using describing functions and impedance equivalence.Based on this model,a critical conduction frequency modulation control method is proposed.This method adjusts the driving frequency of the power switch to vary the output power,enabling continuous operation of the power converter to reduce output voltage ripple.Additionally,real-time adjustment of the conduction time to the critical value ensures soft switching of the power switch.Subsequent simulations and board-level experiments verify the effectiveness of the critical conduction frequency modulation control method.Compared to traditional ON-OFF control method,this approach demonstrates significant advantages in terms of voltage ripple and efficiency.To further leverage the advantages of the critical conduction frequency modulation control method,improve the integration of power converter,and address the issue of limit cycle oscillation during digital implementation in board-level experiments,achieving optimal voltage ripple,this thesis designs a driver and control chip for VHF power converters.This chip is designed and taped out using the HHGrace 180 nm BCD process,and can achieve critical conduction frequency modulation control through analog circuits.System-level test results of the chip demonstrate that under the analog implementation of the critical conduction frequency modulation control method,the minimum output voltage ripple can be reduced to 34 m V,significantly eliminating limit cycle oscillation compared to digital implementation.Compared to the traditional ON-OFF control method,the voltage ripple can be reduced by approximately 80%,while improving efficiency by about 2%.更多还原