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

More documents

Recommendations

Info

Over Charge Prohibition 4.275 ± 0.025V/CellRelease4.075 ± 0.050V/CellDelay Time 1.0sec ± 300msecOver Discharge Prohibition 2.600 ± 0.080V/CellRelease2.900 ± 0.100V/CellDelay Time125 ± 37msecOver Current Prohibition 3A ± 1A (Depend on cell voltage)Releaseby ChargingDelay Time8 ± 4msecCurrent Consumption Operation Max. 5µ[A]Power downMax. 0.1µ[A]Table 3.4: Electric Characteristic of KOKAM Protection Circuit Module [20].3.5 Dissipation system (Shunt regulator)The role of the dissipation system is to prevent the voltage of the batteries to get over 4.2Vby dissipating the exceeding power. There will be one dissipation system, connected to thebatteries bus. The reliability of this system is thus critical. Its failure would result in the lossof the whole mission.The worst case is when solar panels output is maximum and no power is consumed in theCubeSat. We can show that the instantaneous power produced by our five solar panels willnever be higher than 5.5W. This value of 5.5W corresponds to an optimal exposure to sun, analbedo of 30%, operation at MPP [6]. The dissipation system must thus be able to dissipatea current of up to 1.31A (5.5W / 4.2V).3.6 Battery heaterThermal simulations were done by the THER team [7]. Results are shown in Fig. 3.22. Theypredict that, in absence of any temperature control measure, the temperature of the batterieswill fall to -21.4 ◦ C in a cold case, and rise to 36.3 ◦ C in a hot case. However, the recommendedoperating temperature of the batteries is between 0 ◦ C and 45 ◦ C. Therefore, a heater will bedirectly placed on the batteries to keep their temperature above 0 ◦ C.3.6.1 ControlThere are two possible solutions to control the heater. The heater could be controlled by theOBC, or could have an independent control. Table 3.5 shows conveniences and drawbacks ofeach solution.It was difficult to decide between these two solutions. After discussion with the OBC team,the solution of the independent control was selected. The control will take the temperatureof the batteries and let the current flow in the heater when the temperature falls below somepredetermined threshold.36
Figure 3.22: Temperatures of cards in OUFTI-1, in the cold case (left) and hot case (right),during one orbit time [7].Control by OBCUses less components.Less reliable (depends ofOBC).The heater can be controlledby an algorithm.Needs a pin in the PC104port.Independent controlUses more components.Independent of OBC andmeasurement system (morereliable).The control is “dumb”.One pin of the PC104 port isspared.Table 3.5: Comparisons of solutions to control the batteries heater.3.6.2 Supply voltageThe chosen solution is to supply the heater directly from the batteries. The reasons are:• The heater does not really need a regulated voltage.• The heater is independent of the power conditioning unit, which improves reliability.• The electrical supply is near, so that there is no need to have a wire connecting theheater to a voltage regulated output.3.7 USB battery chargerThe sixth face of OUFTI-1 contains an USB port. This is the only interface with the satellitewhen the faces are closed. One of the functions of the USB port will be to allow the chargeof the batteries when the CubeSat is sealed. A current of 100mA can be delivered throughthe USB port, with a voltage of 5V.The USB battery charger is a circuit that manages the charge of batteries when it is37
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 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 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
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?