1. Introduction to Space Systems and Spacecraft Design Space Systems Design Power Systems Design -I

2. Introduction to Space Systems and Spacecraft Design Space Systems Design 2 Power System Design Considerations Power Systems Design -I Power System Requirements Power Sources Power Storage Power Distribution Power Control

3. Introduction to Space Systems and Spacecraft Design Space Systems Design 3 Power Systems Design -I

4. Introduction to Space Systems and Spacecraft Design Space Systems Design 4 Power Systems Design -I

5. Introduction to Space Systems and Spacecraft Design Space Systems Design 5 Power Systems Design -I PrimarySecondary

6. Introduction to Space Systems and Spacecraft Design Space Systems Design 6 Power Systems Design -I Primary – non rechargeable batteries Secondary – rechargeable batteries Electrical Power Battery Storage

7. Introduction to Space Systems and Spacecraft Design Space Systems Design 7 Operating regimes of spacecraft power sources Power Systems Design -I

8. Introduction to Space Systems and Spacecraft Design Space Systems Design 8 Power Systems Design -I Energy Storage Not Rechargeable

9. Introduction to Space Systems and Spacecraft Design Space Systems Design 9 Power Systems Design -INot Rechargeable

10. Introduction to Space Systems and Spacecraft Design Space Systems Design 10 Power Systems Design -I Not Rechargeable Not Good

11. Introduction to Space Systems and Spacecraft Design Space Systems Design 11 Power Systems Design -I Rechargeable Old Technology

12. Introduction to Space Systems and Spacecraft Design Space Systems Design 12 Power Systems Design -I Rechargeable Old Technology

13. Introduction to Space Systems and Spacecraft Design Space Systems Design 13 Power Systems Design -I Rechargeable Old Technology

14. Introduction to Space Systems and Spacecraft Design Space Systems Design 14 Power Systems Design -IRechargeable

15. Introduction to Space Systems and Spacecraft Design Space Systems Design 15 Power Systems Design -I Rechargeable New Technology

16. Introduction to Space Systems and Spacecraft Design Space Systems Design 16 Power Systems Design -I Batteries Most common form of electrical storage for spacecraft Battery terms: Ampere-hour capacity =total capacity of a battery (e.g. 40 A for 1 hr = 40 A-hr Depth of discharge (DOD) = percentage of battery capacity used in discharge (75% DOD means 25% capacity remaining. DOD usually limited for long cycle life) Watt-hour capacity =stored energy of battery, equal to A-hr capacity times average discharge voltage. Charge rate =rate at which battery can accept charge (measured in A) Average discharge voltage =number of cells in series times cell discharge voltage (1.25 v for most commonly used cells)

17. Introduction to Space Systems and Spacecraft Design Space Systems Design 17 Power Systems Design -I Considerations for power calculations We have a battery that has a power capacity of: 1000mA (1000mAHrs)@ 1.2v It can supply 1000mA for 1 hour or 500mA for 2 hours or 250mA for 4 hours @ a voltage of 1.2 v. Power rating of 1000mA x 1.2 v = 1.2 watt hours

18. Introduction to Space Systems and Spacecraft Design Space Systems Design 18 Power Systems Design -I Battery selection:

19. Introduction to Space Systems and Spacecraft Design Space Systems Design 19 Power Systems Design -I Considerations for power calculations Two batteries in series.

20. Introduction to Space Systems and Spacecraft Design Space Systems Design 20 Power Systems Design -I Considerations for power calculations Two batteries in parallel.

21. Introduction to Space Systems and Spacecraft Design Space Systems Design 21 Power Systems Design -I Rechargeable

22. Introduction to Space Systems and Spacecraft Design Space Systems Design 22 Operating regimes of spacecraft power sources Power Systems Design -I

23. Introduction to Space Systems and Spacecraft Design Space Systems Design 23 Power Systems Design -I

24. Introduction to Space Systems and Spacecraft Design Space Systems Design 24 Power Systems Design -I New Technology

25. Introduction to Space Systems and Spacecraft Design Space Systems Design 25 Power Systems Design -I Sun spectral irradianceSolar cell responsePeak sun irradiance

26. Introduction to Space Systems and Spacecraft Design Space Systems Design 26 Power Systems Design -I

27. Introduction to Space Systems and Spacecraft Design Space Systems Design 27 Power Systems Design -I Dual Junction Cell Added by second junction Efficiency

28. Introduction to Space Systems and Spacecraft Design Space Systems Design 28 Power Systems Design -I Use of the Sun’s Spectrum

29. Introduction to Space Systems and Spacecraft Design Space Systems Design 29 Power Systems Design -I

30. Introduction to Space Systems and Spacecraft Design Space Systems Design 30 Power Systems Design -I Triple Junction Cell Added by second junctionAdded by third junction Efficiency

31. Introduction to Space Systems and Spacecraft Design Space Systems Design 31 Power Systems Design -I Reduce Efficiency Good Efficiency

32. Introduction to Space Systems and Spacecraft Design Space Systems Design 32 Power Systems Design -I

33. Introduction to Space Systems and Spacecraft Design Space Systems Design 33 Power Systems Design -I Max Cell Voltage when open circuit Max Cell Current when short circuit

34. Introduction to Space Systems and Spacecraft Design Space Systems Design 34 Power Systems Design -I Peak Power

35. Introduction to Space Systems and Spacecraft Design Space Systems Design 35 Power Systems Design -I Add cell voltages to get string voltage String of cells Parallel strings to cover panel Solar Cell Strings

36. Introduction to Space Systems and Spacecraft Design Space Systems Design 36 Power Systems Design -I

37. Introduction to Space Systems and Spacecraft Design Space Systems Design Power Systems Design -I Shadowing Kills all power

38. Introduction to Space Systems and Spacecraft Design Space Systems Design 38 Power Systems Design -I Use of NiCd batteries required reconditioning Reconditioning not required for Li Ion batteries. Reconditioning battery system Close sw to crowbar battery Close sw to crowbar second battery

39. Introduction to Space Systems and Spacecraft Design Space Systems Design 39 Power Systems Design -I How much Battery Charge Left? Charging causes heating Discharging causes heating

40. Introduction to Space Systems and Spacecraft Design Space Systems Design 40 Power Systems Design -I Some Solar Notes

41. Introduction to Space Systems and Spacecraft Design Space Systems Design 41 Power Systems Design -I 41 Sun Approx Cosine

42. Introduction to Space Systems and Spacecraft Design Space Systems Design 42 Power Systems Design -I Eclipse Parallel Sun Rays Sun Earth Satellite Orbit

43. Introduction to Space Systems and Spacecraft Design Space Systems Design Power Systems Design -I 43 Gravity Gradient Stabilized Sun

44. Introduction to Space Systems and Spacecraft Design Space Systems Design 44 Power Systems Design -I Passive Magnetic Stabilized N S S N S N S N S N S N S N S N S N S N S N S N S N S N S N Sun

45. Introduction to Space Systems and Spacecraft Design Space Systems Design 45 Inertially Stabilized Power Systems Design -I Sun

46. Introduction to Space Systems and Spacecraft Design Space Systems Design 46 Power Systems Design -I Power Systems Design - I or EPS Solar Panels - source Charge Control Batteries Voltage Bus Voltage DC/DC Voltage DC/DC Subsystem

47. Introduction to Space Systems and Spacecraft Design Space Systems Design 47 Power Systems Design -I Radios Fixed voltage busses (5v, -5v, 7v, 3.3v, 12v, etc.) Quieter – generates less noise on voltage bus

48. Introduction to Space Systems and Spacecraft Design Space Systems Design 48 Power Systems Design -I DC/DC Converter/Regulators Regulate 2 Li Ion batteries - ~7.2v  5v “Buck Up” 1 Li Ion battery - ~3.6v  5v Requires less circuitry, more efficient to regulate down Requires more circuitry, less efficient to “buck up” voltage.

49. Introduction to Space Systems and Spacecraft Design Space Systems Design 49 Power Systems Design -I Could be caused by arcing due to spacecraft charging Failure in subsystem that causes a short Feedback on voltage bus from some components Multiple return paths for current to battery – don’t use grounded frame Power cycling required to reset components that have latch up due to radiation

50. Introduction to Space Systems and Spacecraft Design Space Systems Design 50 Power Systems Design -I

51. Introduction to Space Systems and Spacecraft Design Space Systems Design 51 Power Systems Design -I

52. Introduction to Space Systems and Spacecraft Design Space Systems Design 52 Power Systems Design -I

53. Introduction to Space Systems and Spacecraft Design Space Systems Design 53 Power Systems Design -I What type of solar panel system does it take to generate 47.5 watts peak and 27.8 watts average?

54. Introduction to Space Systems and Spacecraft Design Space Systems Design 54 Power Systems Design -I

55. Introduction to Space Systems and Spacecraft Design Space Systems Design 55 Power Systems Design -I Questions?