Piezoelectric resonators have shown promise as efficient, power-dense energy storage element alternatives to continue the miniaturization of DC-DC converters. However, practical piezoelectric resonators diverge from their ideal behavior due to spurious modes that cause high loss regions throughout their operating frequency range. Typically, control of piezoelectric resonator DC-DC converters is constrained to unidirectional power flow each resonant cycle for maximum efficiency operation. However, output power depends on the frequency with such control, which means the converter cannot operate at loads corresponding to spurious mode frequencies. This paper presents a fixed-frequency control mode utilizing the high-quality factor of piezoelectric resonators to avoid spurious modes. The fixed-frequency control enables efficient operation spanning the converter's full load range, demonstrated through a prototype DC-DC converter with a custom fabricated lithium niobate resonator. At a conversion ratio of 60 V to 30 V, spurious modes limit the converter's operating range from 33 W to 51 W using unidirectional power-constrained control, yet the fixed-frequency control extends operation from 33 W to 2 W.

中文翻译：

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用于避免杂散模式的压电谐振器 DC-DC 转换器的固定频率控制

压电谐振器已显示出作为高效、功率密集型储能元件替代品的前景，可继续推动 DC-DC 转换器的小型化。然而，由于在整个工作频率范围内导致高损耗区域的寄生模式，实际的压电谐振器偏离了它们的理想行为。通常，压电谐振器 DC-DC 转换器的控制受限于每个谐振周期的单向功率流，以实现最高效率操作。然而，输出功率取决于这种控制的频率，这意味着转换器不能在与杂散模式频率相对应的负载下运行。本文提出了一种利用压电谐振器的高品质因数来避免杂散模式的固定频率控制模式。固定频率控制可在转换器的整个负载范围内实现高效运行，通过带有定制制造的铌酸锂谐振器的原型 DC-DC 转换器进行演示。在 60 V 至 30 V 的转换比下，杂散模式使用单向功率受限控制将转换器的工作范围限制在 33 W 至 51 W，而固定频率控制将工作范围从 33 W 扩展至 2 W。