Preliminary design of high voltage multi-phase inverter system for hydrogen-electric propulsion

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Date
2023-11-11
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Saudi Digital Library
Abstract
The primary concern in the aviation sector is the substantial impact of greenhouse gas emissions, particularly at high altitudes, resulting from aircraft fuel combustion. However, in electric aircraft, the focus lies on weight reduction, a critical determinant of fuel efficiency and overall performance. Current Power Electronics exhibit deficiencies in energy density and efficiency. In modern aviation, the adoption of electric actuators as a replacement for traditional hydraulic or pneumatic counterparts has been made feasible through advancements in inverter and motor technology, facilitating the integration of electrical power sources into aircraft propulsion systems. The high-power demands of this setup make the conventional converter inefficient. To address this challenge, adopting a three-level DC/AC inverter is a promising solution, offering advantages such as increased efficiency, reduced weight, improved power quality, and incorporating wide band gap (WBG) technologies like silicon carbide (SiC). This paper presents the preliminary design and performance analysis of a three-level inverter hybrid system employing both SiC MOSFET and Si IGBTs, employing LTSPICE and MATLAB Simulink software tools, with MATLAB preferred for its versatility. Two methods for creating lookup table data for SiC MOSFETs are explored. The implementation of the inverter system is divided into two stages, combining SiC MOSFETs and Si IGBTs in a hybrid system to enhance efficiency and cost- effectiveness. Sinusoidal Pulse Width Modulation (SPWM) strategies are employed for precise voltage control, and an Electromagnetic Interference (EMI) filter is incorporated to address potential EMI issues. Inverter's performance was analysed via MA TLAB simulations, identifying areas for improvement under different conditions. However, the research does not consider the electrical design topology, including weight, volume, and thermal management. Different strategies are evaluated, with the last strategy demonstrating higher accuracy and efficiency, achieving a high-rated power output of approximately 1.16 MW with an impressive efficiency of 86.44%. Additionally, the implementation of a 5th-order EMI filter further enhances system performance. The study highlights the importance of data analysis and parameter selection for optimising the inverter's operation, providing valuable insights for efficient power electronic systems. The proposed inverter system showed promise for advancing electric aviation and which was validated by other research results. Further research is recommended for higher efficiency and performance.
Description
The aviation industry significantly contributes to greenhouse gas emissions GHG, particularly notable for the increased release of potent gases such as carbon dioxide and nitrous oxide during high-altitude fuel combustion. These emissions increase the Earth's atmospheric heat retention, accelerating climate change [1]. According to the UK Department for Business, Energy & Industrial Strategy, the per- passenger emissions from air travel surpass those of coach and average petrol car journeys by 6.8 and 1.7 times, respectively [1]. Therefore, a comprehensive approach is imperative to reduce aviation emissions, including improved aircraft efficiency, adopting sustainable fuels, and introducing advanced technologies like electric and hybrid aircraft [2]. Critical to these efforts is enhancing system efficiency, power density, and power generation, which can be achieved through changes to system architecture, distribution, conversion, and inverter systems. Of particular importance are inverters, which contribute to system efficiency and emissions reduction and maintain the safety and reliability of aircraft systems by regulating voltage and frequency [3]. While their mass is a critical consideration due to its influence on an aircraft's overall weight, balance, and consequent range, performance, and efficiency, manufacturers have employed lightweight materials and advanced design techniques, such as silicon carbide (SiC), to address this challenge. SiC's attractive properties—including high thermal conductivity, high voltage capacity, and low power losses—make it suitable for power electronics, including inverters [4]. Despite potential challenges with rapid switching at the component and converter level, SiC inverters can operate at higher voltages and temperatures, leading to increased efficiency, reduced cooling requirements [5], and improved overall performance of electric aircraft and other electric vehicles. Despite challenges such as voltage and current oscillations (overshoot, losses) and high dv/dt that can negatively impact motors [6], the benefits of SiC inverters generally outweigh the downsides, making them a promising solution for high-performance applications, particularly in commercial aviation where size and weight are critical [7].
Keywords
Preliminary design of high voltage multi-phase inverter system for hydrogen-electric propulsion, Wide Bandgap, High Voltage Inverter, Multiphase, hydrogen, Silicon Carbide, electric aircraft
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