1. 1 Electrical Power System By Aziatun Burhan

2. 2 Overview Design goal requirements throughout mission operation: Energy source generates enough electrical power Energy storage stores electrical power Power distribution distributes electrical power Power regulation controls electrical power For a slide like this enlarge the font to fill the slide or fill space with a picture (check other slides as well)

3. 3 Power Budget SubsystemPower consumption (W) Total Power (inc. 20% safety margin) Continuous operation 23.7 ADCS4 Orbit Control3.74 OBC2 Power5 Communication3.05 Camera (idle)2 Non-continuous operation 66 Thermal control **10 Propulsion **30 Camera **15 Total 89.7

4. 4 Mission Power Profile

5. 5 Trade studies summary This trade study examines the option of using only non- rechargeable battery vs solar cells+rechargeable battery system as satellite’s power source. To meet NANOsat requirements, a power source that has low mass and small size is desirable for this mission. Try to make this slide into a couple of bullets rather than sentences

6. 6 Solar cells vs Battery Factors that effect trade study: - Total power consumption and power profile during the mission - Mission life of satellite : 24 hours - Mass and area constraints that come from NANOsat requirement * Solar cells can produce lots of power with little increase in total mass * If power consumption is large, the mass and size of non-rechargeable battery could be greater. - Choice of orbit and type of attitude control - Operating environment

7. 7 Solar cells vs Battery We choose solar cells as the main power source with rechargeable battery to store energy and to provide power during eclipse - Solar cells+ battery has little increase in mass for larger increase in power consumption - Fewer non rechargeable battery that is qualified for space application

8. 8 Solar cell vs Battery Solar cell+batteryNon rechargeable battery MassLessMore Power/massHighLow Mission lengthWeeks-monthsFew hours-one/two days Attitude/Orbit controlOptional / DependantIndependant Effect of FailureNo power during eclipse No power throughout mission Thermal controlLess dependantExtremely dependant CostDo you have cost estimates? Make the table smaller to keep the page number out of it

9. 9 Solar cells Ultra triple junction Gallium Arsenide solar cell 28.0 % BOL efficiency 2.31 V, 16.3 mA/cm² ( ~0.96 W/ cell) 2.3g Customized size: 3.69 cm 6.85cm Area per cell: ~ 25cm²

10. 10 Solar cells layout & assemblies Sides (A) 5 identical solar panels Power source: Direct sunlight, at 45 ° angle from normal direction of plane 91 UTJ GaAs solar cells per side - 13 solar cells per string : 30 V - 7 strings : 2.85 A 40.68 Watt minimum per side during daylight Dimension : 48 cm x 48 cm Area: 2275 cm²

11. 11 Assumption: 2 sides are exposed in direct sunlight at one time. Solar flux is at constant value of 1353 W/m^2 Worst case hot temperature was used to find thermal efficiency for a solar cell, therefore the calculated power output from the a solar panel is the minimum value. Enlarge the font

12. 12 Rechargeable Batteries Saft MPS 176065 Lithium-ion cells 8 cells in series in a battery box Capacity: 5.8 Ah Mean voltage: 3.6 V Battery mass: 1.4 kg (including casing) Maximum DOD: 70% for <500 cycles Charging method: Constant Voltage- constant current + balancing Space qualified 2 battery boxes (for redundant operation with one unit failed)

13. 13 Energy storage requirements: Peak power load: ~90 W Discharge time: 36 min (maximum) Charging time: 0.9 to 1 hour Charge/Discharge cycle / day: 16 Required battery capacity: 2.6 Ah for 75% DOD

14. 14 Demonstration *will recheck the values this weekend

15. 15 Power Management & Distribution SmallSat power management electronics 28V unregulated; MPPT; Modular & Scalable from 30W to 300W Consist of 3 main elements: - Battery Charge Regulator (BCR) - Power Conditioning Module (PCM) - Power Distribution Module (PDM)

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17. 17 Power Distribution Design Power Bus (~28 V) DC-DC step down converter DC-DC Step down converter ADCS FCS COMM OBC Payload (Camera) Thermal control PropulsionPower 5V supply line 12 V supply line

18. 18 Power Distribution ** non continuous operation Continuous power per one orbit period: 23.7 W Maximum power per one orbit period: 89.7 W Average power per one orbit period: 47 W Average power during daylight: 42.5 W Average power during eclipse: 53 W