Abstract
The design of single-phase differential buck inverters has two important considerations, including reducing second-order ripple power using decoupling capacitors and increasing inverter performances. Using larger decoupling capacitors will improve the performance of ripple power reduction and efficiency while reducing power density. Such trade-off has not been fully modeled and investigated, leading to the sub-optimal design of inverters. To address that, in this paper, the trade-off among decoupling capacitance, inverter efficiency and power density are investigated through detailed mathematical modeling and sensitivity study. The trade-off of the volume and power loss of essential inverter components, including power switches, inductors and heatsinks, are also studied to facilitate the inverter design. A fast multi-objective design optimization method based on geometric programming is presented to optimize the inverter efficiency and power density. A 1 kW prototype of a Gallium Nitride (GaN) based inverter has been designed based on the proposed method. A hardware prototype of the inverter has been built and tested, which has an efficiency of 98.02% and power density <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ {4.54\;\mathrm{{kW/dm^{3}}}}$</tex-math></inline-formula> and matches 99% to the presented multi-objective design method. This validates the accuracy and effectiveness of the presented design approach considering detailed trade-off analysis.
Highlights
T HE instantaneous power on the DC-link of single-phase inverters have inherent second-order ripple components that significantly affect the performance of the systems
The proposed design approach was implemented in MATLAB/Simulink and examined with a 1kW gallium nitride (GaN)-based inverter
Four 900V TP90H180PS GaN field-effect transistors (FETs) were used to build the prototype and the device is manufactured by Transphorm
Summary
T HE instantaneous power on the DC-link of single-phase inverters have inherent second-order ripple components that significantly affect the performance of the systems. Conventional solutions to minimize the effects of ripple power is to deploy large electrolytic capacitors at DC-link of inverters [1]. Film capacitors can be used instead, which have a much longer lifetime They cannot be used to directly replace electrolytic capacitors due to the reason of their large volume and high cost [3]. The WBG devices cannot help to address the aforementioned problem of DC-link capacitors because such capacitors are sized according to the low-frequency second-order ripples [5], instead of switching-frequency ripples. Small-sized and long-lifetime film capacitors can be used [7]. This method needs extra active and or passive components, which will inevitably increase the control complexity and volume of the inverters [8], [9]
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