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

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7.3 ActivitiesAs OUFTI-1 is designed for communications in D-STAR, an amateur-radio communicationprotocol, the author aquired the “HAREC” ham-radio license, which allows to use the hamradiofrequencies for radio communications.98
Chapter 8ConclusionsThe work described here corresponds to the second phase of work on the development of theElectrical Power System of OUFTI-1. The objective was to carry the project forward as far aspossible. (The first phase had been carried out by Philippe Ledent during his stay at Thalesduring the summer 2008.)8.1 Accomplished work8.1.1 ArchitectureThe architecture of the EPS as well as interaction between components are now established.The batteries are connected to the main power bus (“batteries bus”). The voltage of thebatteries bus is determined by the state of charge of the batteries. The batteries will beprotected against under-voltage and over-currents by the protection circuit module from themanufacturer. They will be protected against over-voltage by the dissipation system. Finally,they will be protected against the cold by the batteries heater.The solar cells of each face of the CubeSat are connected in series and protected againstreverse-bias current by a Schottky rectifier. This forms a solar panel. Solar panels areconnected to the batteries bus without maximum power point tracking (MPPT) system. Asolar panel is characterized by an I-V curve. The produced power is thus determined by thevoltage of the batteries bus.The power conditioning unit converts power from the batteries bus and provides threestabilized voltage power busses to supply the subsystems of the CubeSat. The protectioncircuit (over-current protection) of each subsystems is located on this subsystem’s electronicboard.The antennas deployment circuit is located on the EPS and is supplied from the batteriesbus.The power budget was computed and there is enough power to supply the satellite andallow D-STAR and AX.25 communications.99
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AcknowledgementsI want to thank the
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Contents1 Introduction 91.1 Cubesat
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4.4.2 Mean case . . . . . . . . . .
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B Power budget worksheet 106C Pictu
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design and the tests are delegated
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Chapter 2Requirements of the EPS2.1
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• The Single-Event Upset (SEU)Thi
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the P-POD. RBF pins must fit within
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Figure 2.6: Top view of the PC104 c
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Chapter 3Design of EPS architecture
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• Voltage (4) and current (5) at
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Figure 3.6: The equivalent circuit
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of our Lithium-Polymer batteries va
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Figure 3.12: I-V curve of a solar p
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3.3.3 CapacityA important value to
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Parameter SLPB723870H4 SLPB554374HN
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of the batteries is kept between -2
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Over Charge Prohibition 4.275 ± 0.
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supplied in 5V. The circuit will be
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Chapter 4The Power Budget4.1 Introd
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Figure 4.1: P-V curve of a solar pa
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4.3.2 Efficiency of convertersTo at
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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
Page 60 and 61: Capacitor selectionFour 10µF ceram
Page 62 and 63: • 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
Page 80 and 81: Figure 5.37: Schematics of the firs
Page 82 and 83: R KR >1.45V100mA − 1.3A35= 23.07
Page 84 and 85: The schematics is shown on figure 5
Page 86 and 87: A commercial model meets all requir
Page 88 and 89: Figure 5.45: Schematics of the heat
Page 90 and 91: PrefixX7X5Y5Z5SuffixTemperature ran
Page 92 and 93: 6.2.1 The second dissipation system
Page 94 and 95: • The antenna deployment system.
Page 96 and 97: 6.3.3 TestsThe engineering model of
Page 100 and 101: 8.1.2 DesignA model of Li-Po batter
Page 102 and 103: [15] Fabien Jordan, Phase B Electri
Page 104 and 105: TaK = 273 + TaC;%Photo-current ther
Page 106 and 107: Appendix BPower budget worksheetIn
Page 108 and 109: 108
Page 110 and 111: Appendix CPictures of the prototype
Page 112 and 113: Appendix DSchematics of the enginee
Page 114 and 115: 876543213V3 CONVERTER AND INPUT FIL
Page 116: 87654321ANTENNA DEPLOYMENT CIRCUITB
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