[论文解读] High-Efficiency Self-Adjusting Switched Capacitor DC-DC Converter with Binary Resolution

Alexander Kushnerov|HAL (Le Centre pour la Communication Scientifique Directe)|Mar 22, 2010

Advanced DC-DC Converters参考文献 47被引用 32

一句话总结

本文提出一种高效率自适应开关电容DC-DC转换器，具备二进制分辨率，通过一种新型数制将二进制小数映射至电容电压水平，实现精确的输出电压控制。通过动态配置浮空电容以维持二进制加权电压，该转换器在宽输入电压范围内显著降低功耗并提升效率，仿真与实验结果均已验证。

ABSTRACT

Switched-Capacitor Converters (SCC) suffer from a fundamental power loss deficiency which make their use in some applications prohibitive. The power loss is due to the inherent energy dissipation when SCC operate between or outside their output target voltages. This drawback was alleviated in this work by developing two new classes of SCC providing binary and arbitrary resolution of closely spaced target voltages. Special attention is paid to SCC topologies of binary resolution. Namely, SCC systems that can be configured to have a no-load output to input voltage ratio that is equal to any binary fraction for a given number of bits. To this end, we define a new number system and develop rules to translate these numbers into SCC hardware that follows the algebraic behavior. According to this approach, the flying capacitors are automatically kept charged to binary weighted voltages and consequently the resolution of the target voltages follows a binary number representation and can be made higher by increasing the number of capacitors (bits). The ability to increase the number of target voltages reduces the spacing between them and, consequently, increases the efficiency when the input varies over a large voltage range. The thesis presents the underlining theory of the binary SCC and its extension to the general radix case. Although the major application is in step-down SCC, a simple method to utilize these SCC for step-up conversion is also described, as well as a method to reduce the output voltage ripple. In addition, the generic and unified model is strictly applied to derive the SCC equivalent resistor, which is a measure of the power loss. The theoretical predictions are verified by simulation and experimental results.

研究动机与目标

• 解决开关电容转换器（SCCs）在目标电压范围外运行时因能量耗散导致的根本性功耗损失问题。
• 在SCCs中实现细粒度的二进制分辨率输出电压控制，以最小化电压间隔并减少功耗损失。
• 开发一种新型数制及硬件映射规则，确保浮空电容能自动被充电至二进制加权电压。
• 将该方法扩展至任意进制，支持升压与降压转换，且输出纹波最小化。
• 推导统一的等效电阻模型，用于量化和预测SCCs中的功耗损失。

提出的方法

• 引入一种新型数制，将目标输出电压表示为二进制小数，实现高精度电压分辨率。
• 设计SCC拓扑结构，使输出与输入之间的空载电压比为由电容配置决定的二进制分数。
• 建立代数规则，将二进制数表示法转换为SCC物理硬件配置。
• 利用被充电至二进制加权电压的浮空电容（例如，Vout = V_in × (b1/2 + b2/4 + ...)）实现高分辨率输出电压控制。
• 应用通用且统一的模型，推导SCC的等效串联电阻（ESR），作为功耗损失的直接度量。
• 通过仿真与实验原型实现并验证设计，包括纹波抑制技术。

实验结果

研究问题

• RQ1 如何重新配置开关电容转换器，以实现低功耗的二进制分辨率输出电压控制？
• RQ2 需要何种新型数制与映射规则，才能确保浮空电容被自动充电至二进制加权电压？
• RQ3 所提出的SCC拓扑结构能否通过减小目标电压级别间的电压间隔，在宽输入电压范围内保持高效率？
• RQ4 统一的等效电阻模型能否准确预测SCCs在不同配置下的功耗损失？
• RQ5 为支持升压转换并减小输出电压纹波，二进制分辨率SCC需进行哪些修改？

主要发现

• 所提出的SCC通过精确的二进制分辨率电压控制最小化能量损失，随着电容数量（位数）增加，目标电压间的间隔减小，从而实现高效率。
• 采用二进制加权电容配置可确保输出电压比精确匹配任意二进制分数，实现细粒度控制且硬件开销极低。
• 通过等效电阻方法进行理论建模，能准确预测功耗损失，仿真结果证实了预测的效率增益。
• 实验验证表明，由于电压误差减小和开关损耗降低，该转换器在输入电压大幅波动时仍能保持高效率。
• 该方法支持升压与降压转换，通过简单的电容重构扩展即可有效减小输出电压纹波。
• 统一模型使SCC拓扑结构的系统性分析与优化成为可能，为未来高效率电源转换设计奠定了基础。