Module Requirements

1. The FloripaSat shall have six solar panels as primary source of energy.
Defined by the team.

2. The solar panels electrical characteristics shall be compliant with the following parameters: Vmpp = 4800 mV ± 150 mV; Impp = 500 mA ± 50mA; at Spectrum: AMO WRC = 1367 W/m² and T = 28 °C.
Defined by the team.

3. The EPS shall control the solar panels in order to keep the energy harvested within 95% of the maximum capability of the panel for all irradiance intensities.
Defined by the team.

4. The EPS shall store the harvested energy in two rechargeable lithium-ion batteries connected in series.
Defined by the team.

5. The batteries electrical characteristics shall be as follows: nominal voltage of 7.4 V ±200 mV (3.7 V ±100 mV each battery) and electrical charge capacity of 3Ah ± 200mAh.
Defined by the team.

6. The batteries shall present a voltage difference of no higher than 25 mV before the series connection.
Defined by the team.

7. The EPS shall provide power to the FloripaSat’s subsystems considering priority criteria and batteries state of charge.
Defined by the team.

8. The EPS shall have 7 power buses:

• Main power bus (batteries voltage ± 200 mV/3A);
• EPS/Beacon (3V3 ± 200 mV/2A);
• PA Transceiver Radio (3V3 ± 200 mV/5A);
• PA Beacon (3V3 ± 200 mV/5A);
• Antenna Module (3V3 ± 200 mV/2A);
• OBDH/Transceiver radio/solar panel sensors (3V3 ± 200 mV/1A);
• RUSH (5V ± 200 mV/3A).

Defined by the team.

9. The EPS shall have a microcontroller in order to perform all its designated tasks.
Defined by the team.

10. The EPS microcontroller shall have one timer with period of 1 s ± 50 ms to control the main EPS tasks.
Defined by the team.

11. The EPS microcontroller shall have one timer with period of 100 ms ± 5 ms to control the MPPT tasks.
Defined by the team.

12. The EPS microcontroller shall have an watchdog to reset the microcontroller in case of software failure.
Defined by the team.

13. The EPS shall have a dedicated chip to monitor the FloripaSat's batteries.
Defined by the team.

14. The batteries monitoring chip shall communicate with the EPS microcontroller through One Wire Protocol.
Defined by the team.

15. The batteries monitoring chip shall measure:

• batteries individual voltage (±5% error);
• batteries charging current (±5% error);
• batteries discharging current (±5% error);
• batteries average current (±5% error);
• batteries accumulated current (±5% error);
• EPS temperature (±2°C error);
• number of charge/discharge cycles of the batteries (0% error).

Defined by the team.

16. The batteries monitoring chip shall provide information about state of charge/discharge control.
Defined by the team.

17. The batteries monitoring chip shall provide information about state of charge of the battery.
Defined by the team.

18. The EPS shall have batteries overvoltage protection: the protection mosfet shall be opened when the batteries voltage is over 8.7V ± 5%.
Defined by the team.

19. The EPS shall have batteries undervoltage protection: the protection mosfet shall be opened when the batteries voltage is under 5.4V ± 10%.
Defined by the team.

20. The EPS shall have batteries overcurrent protection: the protection mosfet shall be opened when the batteries current is over 3.3A ± 5%.
Defined by the team.

21. The EPS shall be able to cut off the power delivering to all subsystems (excepting itself and the beacon transmitter) in case of critical low batteries state of charge scenarios.
Defined by the team.

22. The EPS shall have a batteries heating system controlled by its microcontroller and appropriated power drivers.
Defined by the team.

23. The EPS shall have a measurement system for the batteries temperature.
Defined by the team.

24. The EPS shall be able to control the FloripaSat's batteries temperature within ±2°C steady state error from the set point. Also, EPS shall guarantee that the batteries will operate under appropriate temperature conditions (between 0°C and 45°C ).
Defined by the team.

25. The EPS shall provide PWM signals to control the battery heating system. The period of the PWM signals must be 20 ms ± 1ms and the duty cycles should not differ from the desired value by more than 1%.
Defined by the team.

26. The EPS shall provide drivers for the batteries heating system. The drivers’ mean output voltage must not differ by more than 5% of the desired value.
Defined by the team.

27. The EPS shall operate the FloripaSat's batteries charge/discharge processes avoiding unbalanced cell conditions. The voltage difference between the cells during operation should be no more than 50 mV. Because..
Compliance with CDS 3.3.8.

28. The EPS shall have a step-up converter to charge the batteries from the solar panels with at least 75% of efficiency.
Defined by the team.

29. The EPS microcontroller shall provide PWM signals to control the step-up converter. The period of the signals must be 2 us ± 5%. The duty cycles must not differ from the desired value by more than 5%.
Defined by the team.

30. The EPS shall have an independent circuit to control the step-up converter to charge the batteries from the solar panels in case the microcontroller fails. The frequency of the PWM signal generated should be 500 kHz ± 5% and the duty cycle 58% ± 5%.
Defined by the team.

31. The EPS shall comply with the launcher safety requirements. All the FloripaSat's subsystems shall not be powered before or during the launch.
Compliance with CDS 3.3.1 and 3.3.3.

32. The EPS shall have at least two separation-switches to avoid the system to be powered before/during the launch.
Compliance with CDS 3.3.2.

33. The batteries temperature measurement system shall communicate with the EPS microcontroller through SPI Protocol (2 KHz).
Defined by the team.

34. The EPS shall have UART (@9600 bps) communication for debugging.
Defined by the team.

35. The EPS shall communicate with the beacon microcontroller through UART (@9600 bps).
Defined by the team.

36. The EPS shall do a housekeeping through I2C protocol (100 kHz) in slave mode (OBDH).
Defined by the team.

37. Every solar panel pair shall have a voltage adaptation system for measurements with an error of no more than 1.5%.
Defined by the team.

38. Every solar panel pair adapted voltage from EPS shall be measured by the EPS microcontroller, with an error of no more than 1.5%.
Defined by the team.

39. Every solar panel current from EPS shall be measured individually by a current sensor, with an error of no more than 1.5%.
Defined by the team.

40. Every current sensor output shall be measured by the EPS microcontroller with an error of no more than 1.5%.
Defined by the team.

41. The step-up converter output shall have a voltage adaptation system for measurements with an error of no more than 1.5%.
Defined by the team.

42. The step-up converter output shall be measured by the EPS microcontroller with an error of no more than 1.5%.
Defined by the team.

43. The main power bus shall have a voltage adaptation system for measurements with an error of no more than 1.5%.
Defined by the team.

44. The main power bus voltage shall be measured by the EPS microcontroller with an error of no more than 1.5%.
Defined by the team.

45. The EPS shall have an external connector to charge the batteries.
Defined by the team.

46. The RBF pin shall cut all power to the satellite once it is inserted into the satellite.
Compliance with CDS 3.3.7.1.