Power managment

Power and communication requirements

Power
 OBC -  ? V, ? mA,  ? W
 2 Cameras -  ?V, ?mA, ?W
 Transceiver -  ?
 Battery heating -  ?
 ?

Communication

CUBESAT PERUN-1p

UHF / VHF TRANSCEIVER

Operations

Full and half duplex

 

Modulation

GFSK/GMSK

 

Frequency Range VHF

145-146 MHz

 

Frequency Range UHF

430-440 MHz

 

Output RF Power

1W

 

Antenna connector

MCX

 

Sensitivity

-127 dBm at 4,8 kb/s BER 5%, with FEC

 

Data rates

0.1 kb/s to 38.4 kb/s

 

Protocol

AX25

 

Operating temperature

-40 °C to +85 °C

 

Power Supply

3.3V

 

Dimension and weight

Compatible with cubesat standard

 

Other

RF parameters fully configurable on-orbit

 

 

Specification of power system

Input from 5 plates, one plate is antenna system.

Solar cell efficiency   29%
Area of solar cell 6*10-3 m2
Area of panel not covered by solar cell 4*10-3 m2
 Emissivity solar cell  0.8
 Emissivity panel (Al)  0.09
 Absorptivity solar cell  0.9
 Absorptivity panel (Al)  0.2
Solar insolation 1367 W m-2
Earth insolation 240 W m-2
 Perun 1p mass  1.3 kg
Specific heat Perun 1p 800 Wh kg-1K-1
Boltzmann constant 5.6704 *10-8  W m-2K-4
 Initial Perun 1p temperature  300 K
 
 Solar cell temperature dependence of efficiency
w = w0(1+dw(T-273-C0)) 

C0 – 28 C (test temperature for solar cells efficiency)
dw  - 2.2 *10-3 %/100/K


                                                      blue arrow - x axis; green arrow - y axis; red arrow - z axis
                                                                          Image   <--- click for animation

Acquision of energy from the solar panels during one day (upper part of figure), which is correlated with the total insolation on the sides of Perun 1p(bottom part of figure). Acquisition of energy follows the time when Perun 1p is exposed to Sun and when it is not. It is interesting that in one interval Perun 1p is exposed to Sun for a much longer period than the expected interchange lasting 45 minutes.
                                             Image

Power from the solar panels during one day (upper part of figure), which is correlated with the total insolation on the sides of Perun 1p(bottom part of figure). Power follows the time when Perun 1p is exposed to Sun and when it is not. Oscillations of power is due to the change in temperature of the solar panels.
                                             Image

Temperature of Perun 1p under the assumption that Perun 1p is cube of average heat capacity and mass. Absrption of Solar radiation is determined by the parameters of solar cells and base pannels. Cooling is due to radiation law, again with the parameters of the solar cells and base pannels.
                                             Image