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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.