Design and Implementation of On-board Electrical Power ... - OUFTI-1

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design and the tests are delegated to students. OUFTI may be interpreted as for OrbitalUtility For Telecommunication Innovation. It is also a typical interjection from Liege relatedto astonishment. OUFTI-1 will carry several innovative equipments.1.2.1 D-STARThe main mission of OUFTI-1 is to test the use of D-STAR in space. D-STAR is a newcommunication protocol. It has been developed by the Japanese amateur-radio league (JARL)for the ham-radio community. It can be used on UHF, VHF, and microwave amateur-radiobands. D-STAR is a fully digital protocol. It allows simultaneous data and voice transmission.It also specifies a network connexion method. With D-STAR, a user can contact another userwithin range. He also can pass through a D-STAR repeater station and contact a user in therange of the station. Some D-STAR repeaters also have an access to the internet. A usercan thus ”enter” in the network through a repeater, and contact a user who is in the rangeof another relay station.OUFTI-1 will be the first picosatellite to use the D-STAR protocol in space. The satellitewill act as an extension of the D-STAR repeater of the University of Liège (ON0ULG).1.2.2 The Experimental Electrical Power System (EPS2OUFTI-1 will also test an Experimental Electrical Power System, developed in cooperationwith Thales Alenia Space ETCA. The Experimental EPS is a digitally-controlled flybackconverter. This system will be redundant with a function of the main Electrical Power System(EPS). The Experimental EPS will provide a 3.3V power output for other electrical systems.1.2.3 New generation solar cellsThe satellite will be equipped with last-generation triple-junction solar cells from Azurspacewith en efficiency of 30%.1.3 Role of Electrical Power SystemThe primary role of the Electrical Power System (EPS), which is the subject of this report,is to supply other systems of the CubeSat with appropriate electrical power.This power is collected from the solar panels. Solar cells produce power when they areexposed to direct solar radiations or to indirect radiations from albedo.In orbit, the satellite regularly passes through the shadow of the earth. There, the radiationscaught by the solar cells are not sufficient to generate enough electrical power. Furthermore,even in daylight, D-STAR communications may need more power than the outputof the solar panels. The EPS thus needs batteries to store enough energy for the eclipses andpeak demands.The collected and stored power must then be distributed to other systems. On OUFTI-1,10
subsystems must be supplied with 3.3V, 5V, and/or 7.2V. The EPS has a power conditioningunit, able to deliver the required amount of electrical power at these voltages.The EPS secondary functions.Some important voltages, currents, and temperatures (they are called the ”HousekeepingParameters”) are measured, scaled, converted from analogical to digital, and transferred toan I 2 C bus. The EPS gathers measurements of its own parameters, but also the temperatureof the external faces of the CubeSat.The switches controlling the current for the antenna’s deployment are on the EPS.Heavy radiations can cause ”single event latch-up” in the semiconductor devices on thesatellite. This can burn the component if the power is not turned off quickly enough. Protectingthe power outputs against over-currents was initially one of the secondary functionsof the EPS. The choice has been made to place such protection circuits on other cards, onthe power input of each system. So, the power can be turned on and off for each systemindependently.In short, the primary functions of the EPS are:• Power source• Power storage• Power conditioning and distribution.The secondary functions of the EPS are:• Telemetry measurements and conditioning• Power control of the antenna’s deployment system• Over-current protection (located on user’s cards).11
Page 2 and 3: AcknowledgementsI want to thank the
Page 4 and 5: Contents1 Introduction 91.1 Cubesat
Page 6 and 7: 4.4.2 Mean case . . . . . . . . . .
Page 8 and 9: B Power budget worksheet 106C Pictu
Page 12 and 13: Chapter 2Requirements of the EPS2.1
Page 14 and 15: • The Single-Event Upset (SEU)Thi
Page 16 and 17: the P-POD. RBF pins must fit within
Page 18 and 19: Figure 2.6: Top view of the PC104 c
Page 20 and 21: Chapter 3Design of EPS architecture
Page 22 and 23: • Voltage (4) and current (5) at
Page 24 and 25: Figure 3.6: The equivalent circuit
Page 26 and 27: of our Lithium-Polymer batteries va
Page 28 and 29: Figure 3.12: I-V curve of a solar p
Page 30 and 31: 3.3.3 CapacityA important value to
Page 32 and 33: Parameter SLPB723870H4 SLPB554374HN
Page 34 and 35: of the batteries is kept between -2
Page 36 and 37: Over Charge Prohibition 4.275 ± 0.
Page 38 and 39: supplied in 5V. The circuit will be
Page 40 and 41: Chapter 4The Power Budget4.1 Introd
Page 42 and 43: Figure 4.1: P-V curve of a solar pa
Page 44 and 45: 4.3.2 Efficiency of convertersTo at
Page 46 and 47: Figure 4.3: Consumptions in % in me
Page 48 and 49: Chapter 5Electrical Design of EPS5.
Page 50 and 51: V outV in= D. (5.1)Since D ≤ 1, t
Page 52 and 53: The power losses in the inductor ar
Page 54 and 55: ∆i L,1 + ∆i L,2 = 0, (5.16)V in
Page 56 and 57: Using the value of ∆i L given by
Page 58 and 59: There is no data about the case to
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Capacitor selectionFour 10µF ceram
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• Output voltage: 5V.• Maximum
Page 64 and 65:
Figure 5.12: Burst mode operation (
Page 66 and 67:
Figure 5.14: Simplified schematics
Page 68 and 69:
Figure 5.15: Worksheet for 3.3V con
Page 70 and 71:
sequently, the k was chosen above 0
Page 72 and 73:
where G 1 is the initial control-to
Page 74 and 75:
Figure 5.21: Measured Bode diagram
Page 76 and 77:
Figure 5.26: Equivalence between th
Page 78 and 79:
C f =12πf f R 0f,L f = R 2 0f C f
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Figure 5.37: Schematics of the firs
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R KR >1.45V100mA − 1.3A35= 23.07
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The schematics is shown on figure 5
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A commercial model meets all requir
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Figure 5.45: Schematics of the heat
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PrefixX7X5Y5Z5SuffixTemperature ran
Page 92 and 93:
6.2.1 The second dissipation system
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• The antenna deployment system.
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6.3.3 TestsThe engineering model of
Page 98 and 99:
7.3 ActivitiesAs OUFTI-1 is designe
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8.1.2 DesignA model of Li-Po batter
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[15] Fabien Jordan, Phase B Electri
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TaK = 273 + TaC;%Photo-current ther
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Appendix BPower budget worksheetIn
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108
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Appendix CPictures of the prototype
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Appendix DSchematics of the enginee
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876543213V3 CONVERTER AND INPUT FIL
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87654321ANTENNA DEPLOYMENT CIRCUITB
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