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

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Figure 3.6: The equivalent circuit of a solar cell (Picture from Wikipedia).With,[ ] ) qVjI D = I 0(exp − 1nkTI 0 = K 1 T 3 exp( ) −EgkTV [V ] : Output voltageI [A] : Output currentI L [A] : Photogenerated currentI D [A] : Diode currentI 0 [A] : Reverse saturation currentV j [V ] : Voltage across diodeq [As] : Electric chargek [J/K] : Boltzmann constantT [K] : Temperaturen - : Diode ideality factorK 1 [A/(cm 2 K 3 )] : Manufacturer’s thermal constantE g [J] : Forbidden band energyThe third equation is the Shockley ideal diode equation.3.2.4 Matlab modelBased on this model, the SwissCube team has written a Matlab program to compute the I-Vcurve of a 26.6% efficiency solar cell, as a function of temperature and insolation [15]. Withthe help of parameters given by Azurspace, this code has been adapted to the 3G 30% solarcells in [3]. Some minor mistakes were corrected (i.e. value of the short circuit current) andnow the code can be used to obtain and display an approximation of the I-V curve of our solarcells. Figures 3.7 and 3.8 show I-V and P-V curves for temperatures from -35 ◦ C to +45 ◦ C(minimum and maximum temperatures on solar panels according to thermal simulations),under a full insolation (G = G nom = 1, 350W/m 2 )24
Figure 3.7: Matlab simulation of the I-V curve as a function of temperature.Figure 3.8: Matlab simulation of the P-V curve as a function of temperature.3.2.5 Solar panelsThere will be two solar cells per face, on five faces. The last face is occupied by the antennasand communication ports.A non-regulated power bus has been chosen for the EPS of OUFTI-1. The solar cells andthe batteries are connected to this bus. As a consequence, its voltage is determined by thebatteries (the bus is called the “batteries bus”). The next section will show that the voltage25
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 10 and 11: design and the tests are delegated
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 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
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 98 and 99:
7.3 ActivitiesAs OUFTI-1 is designe
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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