Electric Skateboards and Wind Turbines?

Esk8 Electronics
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Now, what the heck do skateboards have to do with wind turbines? Not a lot, except that a skateboard running downhill IS A TURBINE… It’s the exact SAME HARDWARE… Nice :1st_place_medal:

Both need an esk that is able to control torque (FOC/vesc), where the only difference is the sign (or direction) of this torque, and the direction of the flow of current. It’s an esk in regen mode, but with the nice feature that it is able to spin up out of stall by itself. It can do automatic take-of, and generate lift on the wings by running in normal esk mode, at the slightest wind detected by an air pressure sensor.

I am currently developing a vesc board which I have named FOC KING (prev. F-of-C). FOC KING (prev. F-of-C), but my motivation was not initially to build an electronic skateboard, but instead to build the electronics for a hoistable wind turbine for my sailboat.

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The esk8 forum is great, and I have now ordered two skateboards that I am going to electrify for running both up- and downhill.

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yes indeed

both can be generators,

so’s hydro power, coal power, and nuclear

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Talking about hydropower… I’ve been there already, and you can produce a LOT of power by dragging a propeller after a sailboat - which actually then again makes it kind-of wind power.

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Hi,

I am verry interested in this topic.
I was looking a to vesc generator and I am very happy to find this post.

I have the turbine of a Seahawk VAWT and a small PMG generator so a would like to put them to good use.
https ://www.desertpowerinc.com/pacwind.htm

I have a few questions. :slight_smile:
Is running a lisp script?
Can be connected to a solar inverter?
Can max speed be limited?

Thanks in advance.

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You should be able to program the wind generator logics in Lisp, however I have not tried that myself.
Connected to solar inverter? If this inverter has some kind of MPPT, I don’t think it’s possible, because this MPPT is probably tailored for solar.
Max speed limit? Yes, should be possible to program that - also in lisp - (but I prefer C-language in the firmware). But this will be a software solution only. To be storm proof, you often would like a mechanical safety solution - lets say that one of your phase wires detaches or is cut, then you have a run-away.

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And OMG, I have thought a lot about such mechanical safety solutions. You could design a small piece of hardware with a mechanical relay that shorts all three phase wires when the AC voltage gets above a threshold. The phase wires should then remain clamped together, until reset manually in some way.

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WOW. I was thinking that this a dead topic and no one will answer.

The turbine that i have can sustain in winds +100 mph. The question came from the generator side due tue open voltage is 1 V per 10 rpm so could go over the ESC max voltage.

Regarding connecting to a solar inverter is to avoid charging and discharging a battery.
If this is possible the ESC will power on when the turbine start generating or need an adition power spuply to maintain the mcu running?

I think the low adoption of home wind turbines is due to the lack of a good controller. A good wind ESC could solve home wind generation.

Can I find you on discord? (PM if you want.)

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Yeah you will, unless using a vesc with a “roll to start” feature but that requires a minimum eRPM to work properly

Low adoption is also due to them being loud and annoying AF.

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Clearly I need to learn a lot.
Can you explain more about “roll to start” ?

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It’s a feature done in esk8, most likely a list script but AFAIK it’s also hardware dependant.

What it does it when the vesc is connected to a power source such as a battery and it senses rotation on a motor, either through an encoder or hall sensors, it powers on the VESC.

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Nice.

My idea is to use it for a wind turbine connected to Grid without battery.
What happens when voltage is produced by PMG and the electronics is off?

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You can’t connect it directly to the grid. The BEMF generated by the vesc is output in DC

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In the FreeDRIVE design can i have supply bord power by a secondary sorce?

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You should be able to - it needs 12V and 5V supply.

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Think you’re are right. There is no good controller, and to make one, “intelligent” regenerative braking is the way to go.

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I am a mechanical engineer with some understantgin of electronics so i have a lot if questions :slight_smile:
Could be a solution to use a small bridge rectifier from PMG and connect to supply bord VCC? will that require at lesat 12 v to start the ESC?

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Do you have any data from your boat tubine?
How you calculate the maximum Power on RPM?

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You could have a simple algorithm like this:
Realtime params:

  • RT_rpm
  • RT_power

LOOP:

expPower = getExpectedPower(RT_rpm)
IF (expPover > RT_power):
Increase regenerative braking torque
ELSE:
Decrease regenerative braking torque

ENDLOOP


#define RPM_TO_TIP_SPEED_FACTOR 0.120427718
// = circumference / 60, where circum=2pir

#define POWER_FACTOR 0.7935
// = 0.5blade_efficiencyArea, where blade_efficiency Cp=0.38197 and Area=pi*r^2

float getExpectedPower(float rpm)
{
float windspeed = rpm * RPM_TO_TIP_SPEED_FACTOR / valFloat[TipSpeedRatio_ID]; // Unit is meter/sec

float power = POWER_FACTOR * pow(windspeed, 3) - valFloat[Losses_ID];

if (power < 0) return 0.;
else return power;
}

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This is you TSR, tip-speed-ration - how many times faster the wing-tip is traveling with reference to wind speed. For my turbine the figure was 7.

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This is the losses in the turbine in Watts. For my turbine I set it to 35W