brunoeiterer edited this page Jan 30, 2018 · 10 revisions

FloripaSat EPS Wiki

The Electrical Power System has been designed to harvest, store and distribute energy for the FloripaSat I cubesat mission. The energy harvesting system is based on solar energy conversion through six solar panels attached to the FloripaSat structure. The EPS is designed to operate the solar panels at their maximum power point. The harvested solar energy is stored in two lithium-ion batteries connected in series. The energy distribution is done by several integrated DC-DC converters. The full EPS system is composed of the solar panels, the EPS PCB, the Batteries PCB and the External Batteries Charger PCB.

Highlighted Features

  • Compatible with Gomspace Solar Panels or panel of similar characteristics
  • Compliant with CubeSat standard
  • Low power MSP430 MCU up to 20 MHz
  • Maximum power point tracking
  • Overvoltage, undervoltage, overcurrent and short circuit protection for the batteries
  • Consumption measurement capability
  • Solar panels power measurement capability
  • Batteries electrical measurements capability
  • One 3.3V/1A, two 3.3V/2A, one 5V/3A, two 5V/5A and one battery voltage supply output pins
  • Seven temperature measurements with high accuracy
  • Operates on five energy levels
  • Low power operation capability
  • Board for batteries support
  • Board to control the external charging of the batteries before the flight

General Characteristics

Mechanical Dimensions (LxWxH) Main Board 94 mm x 90 mm x 12 mm
Batteries Board 72 mm x 64 mm x 28 mm
Charger Board 42 mm x 26 mm x 12 mm
Mass Main Board 91 g
Batteries Board 21g
Charger Board 5 g
Operating Temperature -20 ºC to +70 ºC
Thermal Dissipation < 1.3 W
Power Supply Digital Circuits 3.3 V ± 0.1 V
Batteries Charging 4.5 V to 15 V ± 0.1 V
Batteries Control 4 V to 9.2 V ± 0.1 V
Power Consumption Static 0.43 W
Dynamic 5.4 W
Current Sensor Solar Panels up to 600 mA ± 18 mA
Voltage Regulator
TPS5420QDRQ1
up to 300 mA ± 9 mA
Voltage Measurement Solar Panels (+X -Y) up to 4.84 V ± 0.1452 V
Solar Panels (+Y -Z) up to 4.84 V ± 0.1452 V
Solar Panels (+Z -X) up to 4.84 V ± 0.1452 V
MPPT Boost Ouput up to 10 V ± 0.3 V
Main Power Bus up to 10 V ± 0.3 V
Batteries Measurements Voltage up to 4.6 V ± 0.23 V
Current up to 5.12 A ± 0.256 A
Electrical Charge up to 40.96 Ah ± 2.048 Ah
Average Current up to 5.12 A ± 0.256 A
Temperature -128 ºC to 128 ºC ± 2 ºC
Charge/Discharge Cycles up to 512 cycles
Batteries Protection Overvoltage 8.7 V
Undervoltage 5.4 V
Overcurrent 3.3 A
Temperature Measurements -50 ºC to 170 ºC ± 2 ºC
MPPT Efficiency over 95 %
I²C (slave mode) Voltage 3.3 V
Bit Rate up to 400 kbit/s
UART Voltage 3.3 V
Baudrate 4800 bit/s

How to use the EPS PCB

To use the EPS PCB the board needs to be properly powered-on and the code needs to be flashed to the MCU. To accomplish this the Build and Upload tutorial should be followed, along with one of the Power-on tutorials.

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