I'm working on a project about making a portable wind turbine. It's meant to charge phones and batteries using a USB port (which gives out 5 volts of power). We're mechanical engineers, so we're not experts in electronics. We need some help.

We're starting with a brushless DC motor and going up to the USB output. Could you suggest what parts we'll need? We're also thinking of using a gearbox in our design. Do you know of any good companies in the UK that make affordable brushless DC motors and gearboxes?

Also, if you have any easy-to-understand resources that can help us learn more about what we need for this project, that would be really helpful. Thanks so much for any help you can give!

 

Look at this for starters - https://www.portescap.com/en/newsroom/whitepapers/2021/12/running-a-brushed-dc-motor-as-a-generator

 

When back-fed/driven, a BLDC motor generates 3ph AC, so for one, you will need a 3ph full wave rectifier device.
Also the generated voltage increases with RPM rate, so some kind of regulation will be needed.

 

Obviously the size and efficiency of the turbine, together with wind speed, will inform the choice of motor and the charging power available.
I suggest reading up about buck-boost DC-DC converters and MPPT.

 

Probably the low output current from a low voltage DC motor used as a generator will take days to charge a phone.

Horizon Hobby sells a model airplane that uses brushless motors that are operated from a speed controller powered by a 3.2V to 4.2V Lithium battery. The motor is listed in the online manual for the "UMX Twin Otter".
All their other low voltage brushless motors operate from 6.4V minimum so as a generator their output power at your low voltage will be very low.