Changes

==The Basics==

==The Basics==

Satellite power modules are widely known as '''electrical power systems, or EPS'''. If you are purchasing Cubesat components as a kit, the EPS will come as a self contained unit, batteries inluded, with outputs for voltage bus distribution. The EPS can be broken down conceptually into four smaller blocks. They are the [[#Power Sources]], the [[#Energy Storage]], the [[#Power Distribution]], and the [[#Power Regulation and Control]] modules.

Satellite power modules are widely known as '''electrical power systems, or EPS'''. If you are purchasing Cubesat components as a kit, the EPS will come as a self contained unit, with outputs for voltage bus distribution and battery connnections. The EPS can be broken down conceptually into four smaller blocks. They are the [[#Power Sources|power sources]], the [[#Energy Storage|energy storage]], the [[#Power Distribution|power distribution]], and the '''Power Regulation and Control''' modules.

 

 

[[File:Design_Process_for_Power_Subsystems.png]]

==Power Sources==

==Power Sources==

Most satellites store their power through a set of primary and secondary batteries. One can find a table of industry standard batteries and their characteristics below.  

Most satellites store their power through a set of primary and secondary batteries. One can find a table of industry standard batteries and their characteristics below.  

Table of primary batteries.

[[File:Primary_battery_types.png]]

 

==Power Distribution==

==Power Distribution==

It is typical to single a single '''PDS''' in smaller satellites. In larger satellites it is not uncommon to have multiple distribution systems for collections of components. Typically a distribution bus will contain rails of 5v, and 3.3v for Cubesats. For special applications and different desired rail voltages, a modified EPS may be required. This is the critical module that handles voltage protection, isolation, and fault detection within the power block.

It is typical to single a single '''power distribution system (PDS)''' in smaller satellites. In larger satellites it is not uncommon to have multiple distribution systems for collections of components. Typically a distribution bus will contain rails of 5v, and 3.3v for Cubesats. For special applications and different desired rail voltages, a modified EPS may be required. This is the critical module that handles voltage protection, isolation, and fault detection within the power block.

The PDS also typically contains the '''Peak Power Tracking, PPT''' module. The PPT monitors the solar panels and places the appropriate load resistance across the solar panel terminals in order to draw the maximum amount of power from them. Solar panels have a non-linear IV curve, which means their power output changes across loads and voltages. As the sunlight changes the voltage, the PPT adjusts the load to match.   

The PDS also typically contains the '''Peak Power Tracking, PPT''' module. The PPT monitors the solar panels and places the appropriate load resistance across the solar panel terminals in order to draw the maximum amount of power from them. Solar panels have a non-linear IV curve, which means their power output changes across loads and voltages. As the sunlight changes the voltage, the PPT adjusts the load to match.   

Solar cell operating characteristics graph. Caption: the PPT keeps the solar pannels operating along the center line of peak performance.

Solar cell operating characteristics graph. Caption: the PPT keeps the solar pannels operating along the center line of peak performance.

==Power Regulation==

==Common Power values for Cubesats in Industry==

[[Category: Satellites]]

 

 

 

 

 

 

 

 

MIT open courseware http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-851-satellite-engineering-fall-2003/index.htm