A solar power plant is good when there is sun. But most of the CIS is similar to Foggy Albion, at least in the cold season, and many have windows facing the northern part, so you can assemble a small windmill for an emergency source of electricity (smartphones, laptops, cameras).
This is not a 100% finished project, but rather information and test results collected from forums that will help in the manufacture of a small home-made wind turbine.
It is based on a BLDC motor from a gyro scooter, after which a rectifier is a Schottky bridge for 6 diodes. The voltage range is wide since the BLDC motor is ~60kV. For an output over 5V, the rotation is 300 rpm, but the maximum voltage can be much higher.
A perfectly reasonable solution is to use a step-down switching regulator with a wide input voltage range (even >30 V) and conversion to 5 V with high efficiency.
The output in the simplest case can be directly routed to USB, but it is better to embed the 18650 cell in the generator case and charge it with a parallel 5V output to USB. This will provide sufficient inertia by smoothing out the charging current during lighter winds – that is, the built-in storage concept.
For this project, we bought used hoverboards to use BLDC motors for the turbine. During the tests, the EMAX GB4008 engine was used, the parameters are in the table.
It is embedded in a 3D printed part.
The motor was measured with different current values - in CV mode.
Power up to 5 W, with it the turbine should turn around 950 rpm (5 V, 1 A). We have P \u003d 3 windings with R \u003d 7 Ohms each, so if we assume that 1/3 of the total current flows through each winding, then on average at a current of 1 A we lose about 1-2 W to heat the engine from the formula (I / P) ^2*R.
The blades are made of a PVC pipe with a diameter of 11 cm, their length is about 20 cm. The profile of the blades was drawn on a sheet of A4 paper, pasted onto a PVC tube and cut out with a jigsaw. Charging starts at a wind mark of about 20 km / h, with an anemometer it would be more accurate.
Please note that 3D printing must be made from a UV resistant material such as ASA because it will crack after one sunny summer.
In general, such small wind farms need to be carefully thought out and calculated in order for them to make sense and be quite efficient.