Posted by Scott James on August 14, 2008 at 10:56pm
Hi Everyone,I am planning to begin making a solar powered UAV and have spent some time researching Solar Panels , MPPT’s, Airframes and Autopilots. I think the best way to go is to run the Motor / speed controller directly from the Solar panels / MMPT, but also have a small battery to “back up” the electronics just incase the UAV tips upside down etc.. so it has power to recover.I have tested the Powerfilm solar panels but don’t think they will be efficient enough for what I want to do. I think I will use the A-300 panels instead.This is the airframe I am thinking of using.My question is.. Is anyone else out there trying this, thinking about trying this or done this yet??I am interested to see some different approaches to the same problems.
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I have just started to think about this. My goal is to build a solar powered UAV that can cary a smartphone and Arduino Micro. My initial search of existing designs suggested that most of them were overgrown park flyers. My brother has been working on some UAV software for Android that seems like it has a lot of potential. With what he has already done, we can stream video and telemetry of a cellular data connection. It seems like some really cool things could be done by combining a cellular connection with the ability to stay up for hours at a time (potentially all day).
My main concern is cost and the thing I really need help with is solar cell selection.
From what I have gathered from the odd picture of them they have to be huge to actually have enough area to power them, they also should fly high and be a wing. The US did a project like this and it was something in the region of 10m across!
Check out University of Michigan SolarBubbles team goal to design, build and test a solar-powered unmanned aerial vehicle capable of 36+ hours of flight with less than a 15 foot wingspan.
For systems with batt and solar,
One could install two ESC's - one to connect the battery to the Motor, and the second to connect the solar cells to the same motor.
This overcomes the need for an MPPT and a DC to DC converter. The solar circuit includes a capacitor.
When the capacitor is charged above the target voltage (peak mppt for current sun conditions), turn on the Solar ESC until the capacitor drops below the target voltage. If you need battery power, you can use batteries during the time the capacitor is charger. You can vary the solar to battery ratio by changing the cycle ratio, But generally, you'll run on one or the other and not both. The total power is controlled by the throttle level to the ESCs. (don't throttle them up together).
To charge the batteries, include a charging transistor and a cheap lion charging circuit. ($5 model) power this circuit when the capacitor is above target voltage AND you're above target altitude.
(probably a very bad idea to power them both up together as even the power up chirp could cause a short.) don't connect the common ground until after power up.
The objective here is to avoid a complex, inefficient and heavy DC chain between your power sources and the motor.
The parallel ESC's offer a single transistor connection between the solar cells and the motor, and alternatively between the batteries and the motor. MPPT tracking can be managed by adjusting the motor power/climb rate and/or charging rate. (I can't think of any benefits of adding extra transistors in a discrete MPPT between the solar cells and motor.)
2 ESC $20
1 Motor $20
1 Lion Charger $5
1 ArduPilot Pro ($?)
1 Power transistor for Charger
1 Capacitor for Solar
1 Current Sensor for Solar Cells
x Solar Cells
MPPT Algorithm includes measuring current and voltage of solar circuit and adjusting the target voltage up and down to find the voltage at which the solar cells are producing peak wattage. In a separate loop, if the solar voltage is above the target, then use the power, if below, then stop using the power. The cell voltage must be higher than the battery to be useful. The second ESC solves the problem of voltage mismatch between the solar circuit and the battery potential.
Ben
P.S The nasty problem with parallel ESC is the potential for shorts - to address this place a fuse, and perhaps a inductor between the battery ground and the solar ground as this will minimize the effect of an unpleasant H-bridge short. Better would be a self-resetting fuse.
From what I have gathered from the odd picture of them they have to be huge (at least 3m wingspan) to actually have enough area to power them, they also should fly high and be a wing. The US did a project like this and it was something in the region of 10m across!
take look at my project... i am using Powerfilm solar panels that perfectly fit on my plane. they weigh 120grams and producing 1.25amps at full sun... i am using them to power all my equipment (including the brushless motor) together with a bank of batteries... http://borsaci06.com/robotics.html
Replies
thank you very much , i like your Solar UAV, i think Freewing Plane is more better
I have just started to think about this. My goal is to build a solar powered UAV that can cary a smartphone and Arduino Micro. My initial search of existing designs suggested that most of them were overgrown park flyers. My brother has been working on some UAV software for Android that seems like it has a lot of potential. With what he has already done, we can stream video and telemetry of a cellular data connection. It seems like some really cool things could be done by combining a cellular connection with the ability to stay up for hours at a time (potentially all day).
My main concern is cost and the thing I really need help with is solar cell selection.
Hi friends
From what I have gathered from the odd picture of them they have to be huge to actually have enough area to power them, they also should fly high and be a wing. The US did a project like this and it was something in the region of 10m across!
Regards
Sid
Nitrotek
For systems with batt and solar,
One could install two ESC's - one to connect the battery to the Motor, and the second to connect the solar cells to the same motor.
This overcomes the need for an MPPT and a DC to DC converter. The solar circuit includes a capacitor.
When the capacitor is charged above the target voltage (peak mppt for current sun conditions), turn on the Solar ESC until the capacitor drops below the target voltage. If you need battery power, you can use batteries during the time the capacitor is charger. You can vary the solar to battery ratio by changing the cycle ratio, But generally, you'll run on one or the other and not both. The total power is controlled by the throttle level to the ESCs. (don't throttle them up together).
To charge the batteries, include a charging transistor and a cheap lion charging circuit. ($5 model) power this circuit when the capacitor is above target voltage AND you're above target altitude.
(probably a very bad idea to power them both up together as even the power up chirp could cause a short.) don't connect the common ground until after power up.
The objective here is to avoid a complex, inefficient and heavy DC chain between your power sources and the motor.
The parallel ESC's offer a single transistor connection between the solar cells and the motor, and alternatively between the batteries and the motor. MPPT tracking can be managed by adjusting the motor power/climb rate and/or charging rate. (I can't think of any benefits of adding extra transistors in a discrete MPPT between the solar cells and motor.)
2 ESC $20
1 Motor $20
1 Lion Charger $5
1 ArduPilot Pro ($?)
1 Power transistor for Charger
1 Capacitor for Solar
1 Current Sensor for Solar Cells
x Solar Cells
MPPT Algorithm includes measuring current and voltage of solar circuit and adjusting the target voltage up and down to find the voltage at which the solar cells are producing peak wattage. In a separate loop, if the solar voltage is above the target, then use the power, if below, then stop using the power. The cell voltage must be higher than the battery to be useful. The second ESC solves the problem of voltage mismatch between the solar circuit and the battery potential.
Ben
P.S The nasty problem with parallel ESC is the potential for shorts - to address this place a fuse, and perhaps a inductor between the battery ground and the solar ground as this will minimize the effect of an unpleasant H-bridge short. Better would be a self-resetting fuse.
search for "ZEPHYR".
it flew for over 83h.... !!!
take look at my project... i am using Powerfilm solar panels that perfectly fit on my plane. they weigh 120grams and producing 1.25amps at full sun... i am using them to power all my equipment (including the brushless motor) together with a bank of batteries...http://borsaci06.com/robotics.html
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