Development of high-performance modular aeronautical batteries based on LiFePO4 cell technology

Abstract

Today, modern aircraft and flight safety are completely dependent on electronic systems, including engine starting and critical navigation, communication, and control systems. In the failure event of the aircraft's electrical generators, they are batteries that supply power to critical systems. This need has been around for a few decades when the dominant technology was lead-acid or nickel-cadmium batteries. In the last decade there have been modernization initiatives for lithium-ion batteries, light and with better performance, however, in 2013, there was an incident with a Boeing 787 involving smoke and fire risk, therefore there was a retreat in the sector in the use of lithium-ion batteries. This project proposes to develop a LiFePO4-based battery for aeronautical application, replacing old chemicals. During PHASE 1, a functional prototype was developed, demonstrating the feasibility of the LiFePO4 chemistry for aeronautical application. During PHASE 2, the aim is to develop advanced prototypes for qualification in industry standards, such as DO-311, DO-160, DO-254 and DO-178, resulting in safe batteries with good performance. Functionally, the batteries will be modular, allowing a series/parallel association for greater current and voltage capacity, which is motivated by the recent development of electric aircraft, where there is a need for association of many batteries, to reach high currents and voltages. The advantage will be the easy adaptation to other aircraft with different voltage and current requirements without the need to develop a new product, which in the industry ends up being an expensive and time-consuming process, requiring a lot of hardware, software and laboratory qualification tests, in addition to all the procedures with the sector's certification bodies such as ANAC, FAA and EASA. At the beginning of the research, the requirements will be detailed with aircraft manufacturers, who have already shown interest in the project and have already shared data during PHASE 1. The research challenge can be divided into three main areas, mechanics, electronics, and software. The mechanics will focus research on a structure that withstands the extreme environmental conditions of the DO-160, the most challenging being related to mechanical shock, vibration, resistance to water ingress. Load studies and simulations will be carried out on the materials considered for the manufacture of the prototype, so that during the tests there are no qualification problems. The electronics will focus on the functional requirements such as DO-160 capacity, charge, discharge, management and communication, and environmental conditions, particularly temperature, indirect effects of lightning, voltage spikes and transients, and radiated fields. The electronics must be able to communicate with the aircraft, informing battery integrity and charge availability, and recognize the connection with other batteries, monitoring the status of the entire set, and, in case of failure, ensure degradation minimal in performance. During the research, electronic simulations will be carried out in several functional and failure scenarios, bench tests, and operational tests with extreme conditions, validating the project's maturity for qualification tests. Software development will follow DO-178 and becomes quite complex due to the criticality of the system, requiring extensive testing and debugging, and later testing with the developed hardware, physically stimulating the input signals to verify the behavior of the software with the hardware. The final software will be tested against the hardware on the bench and during the DO-311 and DO-160 qualification tests. Successful research will result in advanced prototypes qualified to industry standards. This will make it possible to start the process for certification with ANAC and the sale of the product with manufacturers. (AU)