Implementation of an Intelligent and Reliable Power supply management system of a Small Satellite Engr. Wajid Hassan Department of Electronic Engineering Usman Institute of Technology, Pakistan

Engr. Wajid Hassan

Department of Electronic Engineering

Usman Institute of Technology, Pakistan

Theme of the project The aim is to develop a student based Pakistani satellite within a span of 5 to 10 years. The aim of our project is to design and realize the power subsystem for the miniature (small) satellite. First Pakistani Student based LEO Satellite

The aim is to develop a student based Pakistani satellite within a span of 5 to 10 years.

The aim of our project is to design and realize the power subsystem for the miniature (small) satellite.

Various sub systems of satellite Satellite structure Satellite power system Satellite Attitude Control System Satellite thermal control system Satellite propulsion system Satellite Onboard Computer and Data handling unit. Satellite telemetry and Tele-command system. Satellite Antenna and RF system Satellite earth station (s) Block Digram of a satellite

Satellite structure

Satellite power system

Satellite Attitude Control System

Satellite thermal control system

Satellite propulsion system

Satellite Onboard Computer and Data handling unit.

Satellite telemetry and Tele-command system.

Satellite Antenna and RF system

Satellite earth station (s)

Power Supply Management System The Power supply management system is a system that is providing power sufficiently to all its subsystem. The power management system comprises of the following module. 1 Solar Array. 2 Battery Management Module. 3 Power Distribution Module for loads.

The Power supply management system is a system that is providing power sufficiently to all its subsystem.

The power management system comprises of the following module.

1 Solar Array.

2 Battery Management Module.

3 Power Distribution Module for loads.

Power Supply Management System….(Continued) Solar arrays is the prime source of accumulating power to provide voltages and current for complete system. These voltages are being store in batteries. Battery management system comprises of multiple battery banks that will continue to provide power even if satellite is not aligned to sunlight. This power system architecture incorporates maximum power point tracking system algorithm which is bound to provide maximum power to all its subsystems and loads incase of worsen condition. The algorithm which we used in our project is Perturbation &

Solar arrays

is the prime source of accumulating power to provide voltages and current for complete system. These voltages are being store in batteries.

Battery management system

comprises of multiple battery banks that will continue to provide power even if satellite is not aligned to sunlight.

This power system architecture incorporates maximum power point tracking system algorithm which is bound to provide maximum power to all its subsystems and loads incase of worsen condition.

The algorithm which we used in our project is Perturbation &

Battery management module Battery management module is concerned mainly with the charging, discharging and of the batteries and showing the levels of the voltage in a certain battery. This module is also responsible for switching of battery banks if the power from solar cell is not adequate to run the system. Two power batteries are available in the system. One as a active function and other for redundant approach. One other battery is used for providing reference voltage and is responsible to run the system if the power is at a very critical level and helps in running the most important parts of the satellite.

Battery management module is concerned mainly with the charging, discharging and of the batteries and showing the levels of the voltage in a certain battery.

This module is also responsible for switching of battery banks if the power from solar cell is not adequate to run the system.

Two power batteries are available in the system. One as a active function and other for redundant approach.

One other battery is used for providing reference voltage and is responsible to run the system if the power is at a very critical level and helps in running the most important parts of the satellite.

Power distribution module is responsible for providing required power efficiently with aid to voltage converters for all available subsystems and loads. DC/DC Converters are being used to change DC electrical power efficiently from one electrical level to another. There are many types of converters available. Some of the types which were useful in our project is, Buck Converter. Boost Converter. Buck-Boost Converter. Cuk Converter. Charge pump Converter. We are using Buck and Cuk converter in our project.

is responsible for providing required power efficiently with aid to voltage converters for all available subsystems and loads.

DC/DC Converters are being used to change DC electrical power efficiently from one electrical level to another.

There are many types of converters available. Some of the types which were useful in our project is,

Buck Converter.

Boost Converter.

Buck-Boost Converter.

Cuk Converter.

Charge pump Converter.

We are using Buck and Cuk converter in our project.

Various Existing Topologies of Power Supply System There are three most common power implementation approaches found on today's small satellites. These power system are as follows Direct Energy Transfer (DET) with Battery Bus. DET with Regulated Bus. Maximum Power Point Tracker with Battery Bus.

There are three most common power implementation approaches found on today's small satellites. These power system are as follows

Direct Energy Transfer (DET) with Battery Bus.

DET with Regulated Bus.

Maximum Power Point Tracker with Battery Bus.

Power requirements & Solar Array The requirement for our project is 12V which gives an ampere of 1.5A. This 12V is being down convert to different voltage ratings i.e. 5V and 15V etc. depending upon the load input requirements. Down conversion is done through DC-DC converter. Solar Array Used and Its Characteristics The array which we are using is 20 W with two nodes of voltages available i.e. 24v and 12v. The Array used is Silicon Based.

The requirement for our project is 12V which gives an ampere of 1.5A.

This 12V is being down convert to different voltage ratings i.e. 5V and 15V etc. depending upon the load input requirements.

Down conversion is done through DC-DC converter.

Solar Array Used and Its Characteristics

The array which we are using is 20 W with two nodes of voltages available i.e. 24v and 12v.

The Array used is Silicon Based.

LEO Satellite Characteristics Satellites can operate in several types of Earth orbit. The most common orbits for environmental satellites are geostationary and polar. Geostationary Orbit Medium Earth Orbit Low Earth Orbit Low Earth Orbit Satellites in low earth orbit (LEO) orbit the earth at altitudes of less than 2000 km (1242 miles). Satellites in LEO can get much clearer surveillance images and require much less power to transmit their data to the earth. The satellite which we are planning to build is also for a LEO Earth Orbit. The satellite will be placed on a circular Low Earth Orbit with the inclination of 96 degrees and height of approx. 600 km. Velocity of the satellite on orbit is estimated to be 27000 km/h. Based on these parameters, revolution time has been computed: Torbit : 100 min Tsun : 65 min Teclipse : 35min

Satellites can operate in several types of Earth orbit. The most common orbits for environmental satellites are geostationary and polar.

Geostationary Orbit

Medium Earth Orbit

Low Earth Orbit

Low Earth Orbit

Satellites in low earth orbit (LEO) orbit the earth at altitudes of less than 2000 km (1242 miles).

Satellites in LEO can get much clearer surveillance images and require much less power to transmit their data to the earth.

The satellite which we are planning to build is also for a LEO Earth Orbit.

The satellite will be placed on a circular Low Earth Orbit with the inclination of 96 degrees and height of approx. 600 km. Velocity of the satellite on orbit is estimated to be 27000 km/h.

Based on these parameters, revolution time has been computed:

Torbit : 100 min

Tsun : 65 min

Teclipse : 35min

The simplified overview of satellite power management system

Final Block Diagram of Satellite Power Management System

MPPT algorithms There are many different forms of MPPT implementations but there are two main classes: (1) The Perturbation and Observation method (P & O Method) (2) The Incremental Conductance method. In addition there are other lesser known variations such as Voltage feedback method. Neural network method. Curve fitting method. Load matching method. Implementation of P&O MPPT algorithm

There are many different forms of MPPT implementations but there are two main classes:

(1) The Perturbation and Observation method (P & O Method)

(2) The Incremental Conductance method.

In addition there are other lesser known variations such as

Voltage feedback method.

Neural network method.

Curve fitting method.

Load matching method.

Reliability calculation Power management system is definitely the most essential system on satellite. For this we need to ensure the reliability of the system. Reliability calculations are often measured in mean time between failures (MTBF). The inverse of MTBF is the failure rate. MTBF = (MTTF + MTTR) = 1 / Failure rate. In the Equation above MTTF is mean time to failure and MTTR is repair time. The bath-tub curve shows the life cycle of electronic component, these component should be reliable such that it remain operational in worst case scenarios.

Power management system is definitely the most essential system on satellite.

For this we need to ensure the reliability of the system.

Reliability calculations are often measured in mean time between failures (MTBF).

The inverse of MTBF is the failure rate.

MTBF = (MTTF + MTTR) = 1 / Failure rate.

In the Equation above MTTF is mean time to failure and MTTR is repair time.

The bath-tub curve shows the life cycle of electronic component, these component should be reliable such that it remain operational in worst case scenarios.

Highlights of the project

Future Work It is necessary to cooperate with other group working on the satellite then and then only the satellite power supply system could be tested in actual. There is still a lot of work involved to complete the entire design of Power Supply Management Subsystem. different parts of Power Supply Management Subsystem that needs some improvement are Solar Cells. (GaAs or any other4th generation Solar cell technology) DC/DC Converters. Electromagnetic Considerations. AVR Controller must be used throughout. I2C must be implemented. Simulators must be used for testing the various parts of Power supply system such as 2D and 3D model for Thermal Analysis

It is necessary to cooperate with other group working on the satellite then and then only the satellite power supply system could be tested in actual.

There is still a lot of work involved to complete the entire design of Power Supply Management Subsystem.

different parts of Power Supply Management Subsystem that needs some improvement are

Solar Cells. (GaAs or any other4th generation Solar cell technology)

DC/DC Converters.

Electromagnetic Considerations.

AVR Controller must be used throughout.

I2C must be implemented.

Simulators must be used for testing the various parts of Power supply system such as 2D and 3D model for Thermal Analysis

Conclusion heavy difficulties due to the lack technical details of the satellite and heavy cost involved in developing reliable power supply using satellite graded components. A detailed study of various subsystem was also done. It’s the First student based satellite and others are encouraged to take interest in this demanding project and implement other subsystem in near future. Difficulty faced in converter and sensors Converters Issue With market research it was noted that available converters are highly expensive and are in range between Rs 2000-2500 /= Sensors Issue Current sensors are not available in the market. MAX series for current is available but it will prove to be highly expensive.

heavy difficulties due to the lack technical details of the satellite and heavy cost involved in developing reliable power supply using satellite graded components.

A detailed study of various subsystem was also done.

It’s the First student based satellite and others are encouraged to take interest in this demanding project and implement other subsystem in near future.

Difficulty faced in converter and sensors

Converters Issue

With market research it was noted that available converters are highly expensive and are in range between Rs 2000-2500 /=

Sensors Issue

Current sensors are not available in the market.

MAX series for current is available but it will prove to be highly expensive.

Thank You We dedicate this work to our Beloved Parents, Teachers and all the well-wishers who have always supported Us.

We dedicate this work to our Beloved Parents, Teachers and all the well-wishers who have always supported Us.