现代移动通信系统中高效率高跟踪带宽包络线跟踪电源研究

Envelope tracking (ET) technique is capable of greatly improving the efficiency of the power amplifier in modern wireless communication system, which helps energy conservation and pollution reduction. The ET power supply is the key equipment of the ET system, and it has been facing huge challenges of accurately tracking the radio frequency signal envelope with continuously increased bandwidth and peak-to-average power ratio. The switch-linear hybrid (SLH) ET power supply is a combination of switching-mode converter and linear amplifier, featuring both high efficiency and high linearity, and has been gaining more and more attentions. This project will focus on the SLH ET power supply, aiming for a higher tracking bandwidth and a higher overall efficiency. The series-parallel combined form for SLH ET power supply will be proposed to reduce the output power of the linear amplifier, thus, obtaining a higher overall efficiency. As a basic constituent unit of SLH ET power supply, the switching-mode converter should realize high tracking bandwidth and efficiency. So, the multilevel dc-dc converter is adopted for the switching-mode converter. For the multilevel dc-dc converter, the voltage level numbers and magnitude of voltage levels will be optimized, and the topology and control of the voltage-level provider will be proposed. The spectrum of the radio frequency signal envelope will be analyzed, and the frequency band of the envelope will be properly divided and then assigned to the switching-mode converters and linear amplifier in the proposed series-parallel combined SLH ET power supply, for the purpose of achieving a higher efficiency. The mathematical model of the proposed series-parallel combined SLH ET power supply will be built, and the interaction among the constituent switching-mode converters and linear amplifier will be revealed based on the mathematical model, and then an effective control scheme will be proposed to increase the tracking bandwidth and overall efficiency. Finally, a prototype will be built aiming for a 20 MHz tracking bandwidth.

包络线跟踪(Envelope Tracking, ET)技术可以大幅提高现代移动通信基站功放效率，对于节能减排和缓解环境污染具有重要意义。随着射频输入信号包络线带宽和功率峰均比的日益增大，作为ET技术核心装置的ET电源，其研究极具挑战。本项目针对开关线性复合(Switch-Linear Hybrid, SLH) ET电源，以提高跟踪带宽和整体效率为目标，提出串并联组合架构，以减小线性放大器输出功率；针对多电平开关变换器，研究电平数及电平值优化设计以提高电压拟合效果，研究电平提供单元以提高其效率和各电平稳压精度；提出包络线功率频谱分段方法，并将跟踪带宽合理分配至串并联组合架构SLH ET电源中各变换器；建立串并联组合架构SLH ET电源数学模型，揭示各开关变换器和线性放大器之间的相互影响，提出其协调控制策略，以提高跟踪带宽和电源整体效率。最终将完成一台20MHz跟踪带宽的ET电源样机。

包络线跟踪(Envelope Tracking, ET)技术可以大幅提高移动通信基站功放效率，对于节能减排和缓解环境污染具有重要意义。随着射频输入信号包络线带宽和功率峰均比的日益增大，作为ET技术核心装置的ET电源，其研究极具挑战。本项目从系统架构、控制策略和参数优化设计等方面，开展了高效率高跟踪带宽ET电源的研究。.线性开关复合(Switch-Linear Hybrid, SLH) ET电源结合了开关变换器和线性放大器的优点，可同时获得较高的效率和跟踪带宽。本项目提出了串并联型SLH ET电源架构，以进一步降低线性放大器损耗，提升系统效率。针对电流型开关变换器，提出了准交错并联电流控制策略，减小了线性放大器电流，提高了系统效率；针对AB类线性放大器，提出了减小其下管损耗的方法，进一步提高了系统效率。.针对SLH ET电源中的多电平变换器，提出了其电平数和电平值的优化设计方法，提高了系统效率；提出了基于开关电容变换器的多电平变换器，大幅简化了电路结构；针对串联型和并联型SLH ET电源中的多电平变换器，分别提出了滞环电压预测控制方法和滞环电流预测控制方法，降低了其开关频率，提高了系统效率。.根据包络线功率谱密度曲线，提出了合理的包络线功率频谱分段方法，并提出了由跟踪带宽不同的多个开关变换器构成的SLH ET电源结构。选择两个跟踪带宽不同的开关变换器构成SLH ET电源，并针对慢速变换器和快速变换器，分别提出了谷值点电流控制方法和准临界连续模式电流控制方法。.分别建立了串联型、并联型和串并联型SLH ET电源的数学模型，分析了各开关变换器和线性放大器之间的相互影响机理，并提出了相应的抑制方法以消除变换器之间的相互影响，有效提高了系统效率和输出电压线性度。.本项目的研究将为研制高效率高跟踪带宽的ET电源提供重要的理论基础，其研究成果可应用于移动通信基站和便携式设备中的通信电源。