Tokyo Institute of Technology CUTE-I Electrical Power Subsystem (EPS)

Last updated, Jun 24th, 2003

Function

1) Controlling electric power generated by solar cells.
2) Sharing solar power between internal device and lithium ion battery charger suitably.
3) Regulating electric power high efficiently.
4) Measuring the solar cell generated voltage, current, Li-Ion charge/discharge current and bus voltage.
5) Measuring the temperature of circuit board, regulator, and battery.

Cirtcuit Diagram

Click to enlarge.

Device

CUTE-I EPS generally consists of comsumer devices except for the solar cells.

<Battery>
CUTE-I has lithium-Ion secondary batteries as the internal power storage. The following table showes the specification of the lithium-ion battery. CUTE-I battery consists of 4-parallel configuration (4160mAh).

Specifications of Lithium-Ion Battery
Nominal Capacity		1040mAh
Nominal Voltage		3.8V
Charging Voltage		4.2+/-0.05V
Cathode Materials		Cobalt
Anode Materials		Graphite
Dimensions (W,T,H)		33.8 x 6.5 x 66.6mm
Cycle Life		500cycle
Operationg Temperature Range	Charge	-0'C to 45'C
	Discharge	-20'C to 60'C
	Storage	-20'C to 40'C
Weight		32g

<Solar Cell>
CUTE uses high efficiency and thin silicon solar cells.
The following table shows the specifications and electrical performance.
The estimation of generated electric power is more than 1.5W.

Specifications of Silicon Solar Cells
Cell Dimension (Original size)	4 x 6 cm (Cut Available)
Cell Thickness	100um
Voc	630 mV
Isc	1125mA
VL	530mV
IL	1038mA
Pmax	550mW
Fill Factor	0.78
Efficiency	16.9%
AM0 135.3mW/cm2 , 28 degrees

<Regulator>
CUTE-I required voltages are...
- 3.3V: OBC, sensors, TNC,...
- 5.0V: TCXO
- 3.8V: CW Tx, FM Tx, FM Rx.

CUTE-I EPS supplies the suitable and stable voltage using high-efficient DC-DC converter.

Circuit Board


Front	Back