Fusco, Gaia (2010) Innovative aspects of design, integration and test of satellite equipments and systems. [Tesi di dottorato] (Unpublished)
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|Item Type:||Tesi di dottorato|
|Uncontrolled Keywords:||Innovative Space Equipments|
|Date Deposited:||02 Dec 2010 21:46|
|Last Modified:||30 Apr 2014 19:44|
In recent years, the growing interest in the use of satellites as a quick and cheap way to access space, is increasing the request of new-concept, lower cost, re-usable and flexible systems. A good answer to such a growing demand is the development of innovative high-performance architectures compatible with a wide range of platforms and applications and compliant with ECSS standards. The Ph.D. activities start in this frame, as a cooperation between the University “Federico II” of Naples and the Italian Company Carlo Gavazzi Space S.p.A.. The research work is focused on the design, integration and validation of new-concept satellite equipments, such as a Li-ion modular battery and a magnetic actuator. Starting from an evaluation of the technologies state-of-the-art and from an assessment of the products currently available on the market, the main potential innovative aspects (able to improve the product characteristics while reducing development costs and times) are pointed out. A critical analysis of the potential innovations is carried out, including the description of the benefits, as well as the strategies to manage the drawbacks. The design of both the modular battery and the magnetic actuator is completely ITAR free and characterized by a simple and reversible integration process. It is also worth mentioning that, for the first time, thanks to an Italian research project, an Italian space company presents itself on the space market as an internationally recognized supplier of batteries and magnetic actuators for space applications. The Li-ion battery is modular in the sense that it can satisfy a large number of energy requests for different satellite configurations by simply adding or removing basic elements named “modules”, i.e. it does not need to be re-designed and re-qualified for each mission. Each battery module, including eight Saft MPS176065 cells, is completely self-standing from a structural, thermal, and electrical point of view. The first flight opportunity for the modular battery is represented by Lares, i.e. a mission of the Italian Space Agency (ASI). Lares is the payload for the qualification flight of Vega launcher. Lares battery has been manufactured and integrated as a proto-flight model and has been submitted to a successful acceptance campaign, including performance, vibration, and thermal tests. The next flight opportunities for the modular battery are the ASI satellite missions Miosat and Prisma, and the ESA mission named Eseo. A very promising future evolution of the modular battery design is represented by a hybrid Li-ion/supercapacitor battery system able to satisfy the requirements of satellite missions characterized by high peak power requests. The integration of supercapacitors with Li-ion cells can increase battery lifetime and significantly reduce the total mass of the energy storage unit. The integration of supercapacitors in the battery system requests for an accurate evaluation of the use of such technology in the space environment and of the impacts on both Electrical Power Subsystem and Spacecraft System design. A magnetic actuator (or torque rod) for satellite applications consists of a cylindrical ferromagnetic rod winded by a copper wire. The current circulating into the wire determines a magnetic dipole moment interacting with the earth magnetic flux density. This interaction produces a mechanical torque for satellite attitude control. The equipment, designed in the frame of the Ph.D. activities, is characterized by a simple and highly-reversible integration process thanks to an innovative housing and to a non-elastomeric thermal filler. The magnetic core has been selected as an off-the-shelf (non-custom) ferromagnetic alloy, minimizing procurement times and minimum order quantity. The design process, taking into account the demagnetizing field as function of the core shape, follows three main steps: the first is the definition of the core geometry, the second is the selection of the core material, and the third is the sizing of the winding. The actuator design has been preliminary verified by a numerical simulation and successfully validated by a full qualification campaign including performance, vibration, and thermal tests. Part of the Ph.D. work has been also dedicated to the sizing of the Electrical Power Subsystem (including the Li-ion modular battery as energy storage unit) for different ASI/ESA missions and to further spacecraft-level system activities such as the integration of a telecom payload on a pre-existing satellite platform, and the modification of the platform architecture due to a postponement of the satellite launch.
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