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

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• The Single-Event Upset (SEU)This is when a high energy particle hits a logic device and changes digitally stored dataor causes a gate to open or close at the wrong time.• The Single-Event Latch up (SEL)The SEL is when a high energy particle directly damages the device. It can, however,be corrected if the SEL is detected and the power to the device quickly turned off, thenturned back on.• The Single-Event Burnout (SEB)This is the case where the device is destroyed.The radiation dose is estimated to more than 10 5 [rad]. A protection against SEL can beprovided to the subsystems with current-limiter circuits. There is no particular protectionagainst SEU and SEB except reducing the effect of the radiations inside the satellite with alayer of shielding aluminium (less than 2.10 4 [rad] with 2mm of aluminium) [6]. There arecomponents designed and/or tested to be more resistant to radiations. Such componentsshould be used in the more critical systems of the EPS.TemperaturesThe temperatures in space, when the satellite is turned on, will essentially depend of thethermal design. The temperature ranges are not the same everywhere in the satellite. Thermalsimulations give an idea of the temperature at different points of the CubeSat. Following thelatest simulations [7], the external temperature will vary the most (from -33 ◦ C to +40 ◦ C),the temperature of the EPS card will stay between -22 ◦ C and +37 ◦ C, and the temperatureof batteries card between -22 ◦ C and +37 ◦ C. The EPS must thus be able to work within theseranges.• Solar cells must be selected so that they are able to work in the predicted range of -33 ◦ Cto +40 ◦ C.• The electronics on the EPS card must be designed to be able to operate from -22 ◦ Cto +37 ◦ C (PCB T ◦ ). Wider ranges were given by the first simulations. We decidedot use components with an operating temperature range of at least -40 ◦ C to +85 ◦ Cas ”absolute maximum rating”. The temperature tests have been done at -30 ◦ C and+70 ◦ C.• Lithium-Polymer batteries can withstand 0 to +45 ◦ C during charge and -20 to +60 ◦ Cduring discharge (but with a significant loss of capacity under 0 ◦ C) [20]. A solutionmust be found to maintain the batteries card in these ranges of temperature.14
2.2.2 LaunchVibrations and accelerationsThe payload of Vega will be subjected to vibrations during the launch. The maximum amplitudeand the frequency of the vibrations at the base of the launcher are characterized infigure 2.2.Figure 2.2: Sine excitation at spacecraft base [14].The effects of acceleration during launch are not to be underestimated. The payload ofVega has to be able to withstand an acceleration of 15g [14], even if it will probably be lowerin reality.Special attention must be paid to the fixation of heavy components. Also, componentscould be damaged by the bending of the PCB under vibrations and accelerations. Automotivecomponents will be chosen whenever possible.TemperaturesThe launch vehicle will pass through several atmospheric layers with specific temperatures.Inside Vega LV, the CubeSat will endure temperatures of -40 ◦ C to 80 ◦ during launch [13].Components of the EPS have to be able to withstand such temperatures during storage (theCubeSat is inactive during launch). Components with a working temperature range of -40 ◦ Cto 85 ◦ C should not have any problems.The batteries are still the most sensible component. Their storage temperature shouldstay between -20 ◦ C and 60 ◦ C [20]. A passive solution must be found to protect them duringlaunch. Thermal insulation and thermal inertia will certainly help.Regulations for CubeSatsFollowing articles are extracted from the document ”CubeSat Design Specifications” [12]:3.3.1 No electronics shall be active during launch to prevent any electrical or RF interferencewith the launch vehicle and primary payloads. CubeSats with rechargeable batteries shallbe fully deactivated during launch or launched with discharged batteries.3.3.2 One deployment switch is required (two are recommended) for each CubeSat. Thedeployment switch should be located at designated points (Appendix A).3.3.5 A remove before flight (RBF) pin is required to deactivate the CubeSats duringintegration outside the P-POD. The pin will be removed once the CubeSats are integrated into15
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 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
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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