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Introduction to Space Systems and Spacecraft Design Space Systems Design Power Systems Design -II.

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Presentation on theme: "Introduction to Space Systems and Spacecraft Design Space Systems Design Power Systems Design -II."— Presentation transcript:

1 Introduction to Space Systems and Spacecraft Design Space Systems Design Power Systems Design -II

2 Introduction to Space Systems and Spacecraft Design Space Systems Design 2 Power Systems Design II Power Systems or EPS

3 Introduction to Space Systems and Spacecraft Design Space Systems Design 3 Power Systems Design II

4 Introduction to Space Systems and Spacecraft Design Space Systems Design 4 Power Systems Design II Look at the parts of the EPS

5 Introduction to Space Systems and Spacecraft Design Space Systems Design 5 Power Systems Design II Take Solar Panel

6 Introduction to Space Systems and Spacecraft Design Space Systems Design 6 Power Systems Design II

7 Introduction to Space Systems and Spacecraft Design Space Systems Design 7 Power Systems Design II What do we need from the solar panel? What are the attributes of a solar panel? 1.Total output power of solar panel. 2.Voltage of solar panel. 3.Maximum packing factor. 4.Efficiency of the solar cells. 5.Operating temperature of the panels. Lets go back and look at the solar cell.

8 Introduction to Space Systems and Spacecraft Design Space Systems Design 8 Power Systems Design II This dual junction cell 1.Has an efficiency of ~ 22% 2.Open circuit voltage ~ 2.2v 3.Size – 76 x 37 mm Lets go back and look at the solar cell.

9 Introduction to Space Systems and Spacecraft Design Space Systems Design 9 Power Systems Design II This dual junction cell 1.Has an efficiency of ~ 22% 2.Open circuit voltage ~ 2.2v 3.Size – 76 x 37 mm Solar cell has an I-V curve like this

10 Introduction to Space Systems and Spacecraft Design Space Systems Design 10 Power Systems Design II What are the attributes of a solar panel? 1.Total output power of solar panel. 2.Voltage of solar panel. 3.Maximum packing factor. 4.Efficiency of the solar cells. 5.Operating temperature of the panels. This dual junction cell 1.Has an efficiency of ~ 22% 2.Open circuit voltage ~ 2.2v 3.Size – 76 x 37 mm Looked at the solar cell.

11 Introduction to Space Systems and Spacecraft Design Space Systems Design 11 Power Systems Design II What are the attributes of a solar panel? 1.Total output power of solar panel. 2.Voltage of solar panel. 3.Maximum packing factor. 4.Efficiency of the solar cells. 5.Operating temperature of the panels. Need to select a battery to design for solar panel voltage

12 Introduction to Space Systems and Spacecraft Design Space Systems Design 12 RechargeablePower Systems Design II

13 Introduction to Space Systems and Spacecraft Design Space Systems Design 13 Power Systems Design II Use a lithium ion battery Li Ion batteries = 3.6 v nominal Design Criteria for charging Li Ion battery: 1.Need 10-15% more voltage to charge than the nominal voltage. 2.Here we would need solar panel voltage of ~ 4.0 – 4.2v to charge this battery. Design Criteria solar panel: 1.Number of cells = Max voltage/cell voltage. 2.Take minimum number of whole cells. # cells = (4.2v/string)/(2.2v/cell) = 1.9 or 2 cell for a string voltage of 4.4v

14 Introduction to Space Systems and Spacecraft Design Space Systems Design 14 Power Systems Design II

15 Introduction to Space Systems and Spacecraft Design Space Systems Design 15 Power Systems Design II Use two lithium ion batteries Li Ion batteries = 7.2 v nominal Design Criteria for charging Li Ion battery: 1.Need 10-15% more voltage to charge than the nominal voltage. 2.Here we would need solar panel voltage of ~ 8.0 – 8.3v to charge this battery. Design Criteria solar panel: 1.Number of cells = Max voltage/cell voltage. 2.Take minimum number of whole cells. # cells = (8.3v/string)/(2.2v/cell) = 3.77 or 4 cell for a string voltage of 8.8v Lets be conservative and use 5 cells for 11v.

16 Introduction to Space Systems and Spacecraft Design Space Systems Design 16 Power Systems Design II Now we have: Two Li Ion batteries = 7.2 v nominal 5 cells for 11v to charge with.

17 Introduction to Space Systems and Spacecraft Design Space Systems Design 17 Power Systems Design II What are the attributes of a solar panel? 1.Total output power of solar panel. 2.Voltage of solar panel. 3.Maximum packing factor. 4.Efficiency of the solar cells. 5.Operating temperature of the panels. What is packing factor? Got

18 Total Panel Area Introduction to Space Systems and Spacecraft Design Space Systems Design 18 Power Systems Design II Packing Factor Packing Factor = Total Cell Area/ Total Panel Area Total Cell Area

19 Introduction to Space Systems and Spacecraft Design Space Systems Design 19 Packing Factor What do you do if given a fixed size panel on which to put solar cells and you have these different size solar cells? Fixed solar panel size Cell type 3 Cell type 1 Cell type 2 Power Systems Design II

20 Introduction to Space Systems and Spacecraft Design Space Systems Design 20 Packing Factor What do you do if given a fixed size panel on which to put solar cells and you have these different size solar cells? Power Systems Design II

21 Introduction to Space Systems and Spacecraft Design Space Systems Design 21 Power Systems Design II Now we have: 5 cells for 11v where the string has all of the cells hooked in series 11v Total Panel Area How do you mount these 5 cells on this panel?

22 Introduction to Space Systems and Spacecraft Design Space Systems Design 22 Power Systems Design II How do you mount these 5 cells on this panel? NO! OK! Visually we can see a very poor packing factor.

23 Introduction to Space Systems and Spacecraft Design Space Systems Design 23 Power Systems Design II What if the cells were bigger? Oh Oh! Now you have only 4.4v in the string.

24 Introduction to Space Systems and Spacecraft Design Space Systems Design 24 Power Systems Design II Cant do. All cells for a single string must be on same face. Got a cube? Put other cells on another face?

25 Introduction to Space Systems and Spacecraft Design Space Systems Design 25 Power Systems Design II Where are we now in the solar panel design? What are the attributes of a solar panel? 1.Total output power of solar panel. 2.Voltage of solar panel. 3.Maximum packing factor. 4.Efficiency of the solar cells. 5.Operating temperature of the panels. Assume we could mount the 5 cells on a panel, what is total power for the cells selected? Got Not got, but understand

26 Introduction to Space Systems and Spacecraft Design Space Systems Design 26 Power Systems Design II How much power from these cells? 5 cells for 11v 11v One cell area = 76 x 37 mm = 2812 mm^2 Total cell area = 8*2812 = mm^2 = 2.25 x10-2 m^2 We have 1350 watts/m^2 from the sun in space Direct power = (1350 w/m^2) x (2.25 x10-2 m^2) = 34.4 watts Converted power = direct power x cell efficiency = 34.4 w x 0.22 eff 7.5 watts = 7.5 watts For this dual junction cell 1.Has an efficiency of ~ 22% 2.Open circuit voltage ~ 2.2v 3.Size – 76 x 37 mm

27 Introduction to Space Systems and Spacecraft Design Space Systems Design 27 Power Systems Design II Where are we now in the solar panel design? What are the attributes of a solar panel? 1.Total output power of solar panel. 2.Voltage of solar panel. 3.Maximum packing factor. 4.Efficiency of the solar cells. 5.Operating temperature of the panels. Now we can assume to start: 1.panel is at 90 degrees with sun – max power 2.operating temperature 20 degrees.. Centigrade – 22% eff Got Not got, but understand Got Dont forget, temperature counts a lot.

28 Introduction to Space Systems and Spacecraft Design Space Systems Design 28 Start here Tuesday for IdahoPower Systems Design II

29 Introduction to Space Systems and Spacecraft Design Space Systems Design 29 Power Systems Design II Now that we have beat our way through the solar panel design lets go look at the some more parts of the EPS.

30 Introduction to Space Systems and Spacecraft Design Space Systems Design 30 Power Systems Design II Power Systems or EPS What is this?

31 Introduction to Space Systems and Spacecraft Design Space Systems Design 31 Power Systems Design II Power Systems or EPS Back bias diode When panel 1 is shaded, the back bias diode keeps the current from flowing backwards through panel 1, when panel 2 is generating a voltage across it. Panel 1 Panel 2

32 Introduction to Space Systems and Spacecraft Design Space Systems Design 32 Power Systems Design II Power Systems or EPS What is this ? RV Measure current by measuring voltage across a low resistance precision resistor

33 Introduction to Space Systems and Spacecraft Design Space Systems Design 33 Power Systems Design II Power Systems or EPS

34 Introduction to Space Systems and Spacecraft Design Space Systems Design 34 Power Systems Design II Power Systems or EPS

35 Introduction to Space Systems and Spacecraft Design Space Systems Design 35 Power Systems Design II

36 Introduction to Space Systems and Spacecraft Design Space Systems Design 36 Power Systems Design II

37 Introduction to Space Systems and Spacecraft Design Space Systems Design 37 Power Systems Design II Expanded subsystem control

38 Introduction to Space Systems and Spacecraft Design Space Systems Design 38 Power Systems Design II Expanded subsystem control

39 Introduction to Space Systems and Spacecraft Design Space Systems Design 39 Power Systems Design II What does a charge regulator do? 1.Controls voltage from PV to battery 2.Controls rate of charge 3.Prevents overcharging 4.Can boost or buck PV voltage to match battery needs.

40 Introduction to Space Systems and Spacecraft Design Space Systems Design 40 Power Systems Design II Expanded subsystem control

41 Introduction to Space Systems and Spacecraft Design Space Systems Design 41 Power Systems Design II Consider: When high current occurs in a subsystem, it could be from latch-up. What to do? Cycle power. Where do you do this – hardware controlled in the EPS.

42 Introduction to Space Systems and Spacecraft Design Space Systems Design 42 Power Systems Design II Consider the satellites attitude control for solar power generation.

43 Introduction to Space Systems and Spacecraft Design Space Systems Design 43 Eclipse Parallel Sun Rays Sun Earth Satellite Orbit Power Systems Design II

44 Introduction to Space Systems and Spacecraft Design Space Systems Design 44 Gravity Gradient Stabilized Power Systems Design II

45 Introduction to Space Systems and Spacecraft Design Space Systems Design 45 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 Power Systems Design II

46 Introduction to Space Systems and Spacecraft Design Space Systems Design 46 Inertially Stabilized Power Systems Design II

47 Introduction to Space Systems and Spacecraft Design Space Systems Design 47 Power Systems Design II

48 Introduction to Space Systems and Spacecraft Design Space Systems Design 48 Power Systems Design II

49 Introduction to Space Systems and Spacecraft Design Space Systems Design 49 Power from sun in orbit ~ 1350 watts/meter 2 Power from cells on ground ~ 35% less than in space Can get some power form albedo – earth shine ~ 35% Some Solar Notes Power Systems Design II

50 Introduction to Space Systems and Spacecraft Design Space Systems Design 50 Power Systems Design II

51 Introduction to Space Systems and Spacecraft Design Space Systems Design 51 Power Systems Design II Need to consider the power requirements of all of the subsystems and when they are used to build a power budget.

52 Introduction to Space Systems and Spacecraft Design Space Systems Design 52 Power Systems Design II Questions?


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