Electrical Power System (EPS) Role

4 EPS

DESIGN REQUIREMENTS

Issue : 1 Rev : 0

16/06/2006

Page : 12 of 43

This chapter will enumerate the different design requirements. First, the physical, electrical and data flow requirements will be listed and then we will speak about some other important specifications.

4.1 Physical structure requirements

The physical structure requirements for the EPS are principally the mass allocation, the PCB surface and the battery volume. So here are these physical constraints :

- Mass allocation : 130 g (given at the Team Meeting 16-03-06)

- PCB dimensions : 88 x 98 mm (given by Structure and Configuration subsystem)

- Battery volume : 45 x 15 x 90 mm (given by Structure and Configuration subsystem)

Batteries (black)

EPS PCB (blue)

Payload

Figure 6 : Batteries and PCB position

Ref.: S3-A-EPS-1-0-EPS.doc

Issue : 1 Rev : 0

16/06/2006

Page : 13 of 43

4.2 Electrical requirements

No electronics may be active during launch to prevent any electrical of RF interference with the launch vehicle and primary payloads. CubeSats with rechargeable batteries must be fully deactivated during launch or launched with discharged batteries.

4.3 Data Flow requirements

ADCS need power information from each side covered by cells. In fact, ADCS will use these power datas to determine the satellite attitude. This is an important constraint that we have to include in our design.

4.4 Other Specifications

4.4.1 Remove before flight pin

A remove before flight (RBF) pin is required to deactivate the CubeSats during integration outside the P-POD. The pin will be removed once the CubeSats are placed inside the P-POD. This pin will be directly connected to EPS.

4.4.2 Thermal requirements

Operating temperature range is expected to be -40°C to 70°C.

4.4.3 Deployment and Transmission delay

To allow adequate separation of CubeSats, antennas may be deployed 15 minutes after ejection from the P-POD (as detected by CubeSat deployment switches).

CubeSats may enter low power transmit mode (LPTM) 15 minutes after ejection from the P-POD.

LPTM is defined as short, periodic beacons from the CubeSat.

CubeSats may activate all primary transmitters, or enter high power transmit mode (HPTM) 30 minutes after ejection from the P-POD.

Ref.: S3-A-EPS-1-0-EPS.doc