Basic Circuit Help. thanks

[Maru1]

Background information: I'm designing a braking system for a mini wind turbine. My idea is to connect a low value resistor across the end terminals of the motor to increase current and torque. When not braking, there is a 10 ohm resistor connected across end terminals of the motor by default. I only need a basic idea for a circuit since this project is in early stages.

https://i.imgur.com/h7HnxCP.png
Is this something I should be aiming for or is that stupid?

Also this braking system should be activated once the wind speed reaches a certain speed, If I have a device that measures wind speed how would I create a circuit so that I get the 0.1 ohm resistor between the end terminals of motor instead of 10 ohm resistor automatically

All help is appreciated.

With thanks
Maru

 

[Audioguru]

You do not need to switch both ends of the resistors. Connect the resistors to one end of the motor and switch the resistor to the other end with a relay, a transistor or a Mosfet.

 

[Maru1]

You do not need to switch both ends of the resistors. Connect the resistors to one end of the motor and switch the resistor to the other end with a relay, a transistor or a Mosfet.

Thanks for the reply. Can you give me an idea of how that would look (diagram in Microsoft word or something similar).

 

[betwixt]

A mechanical furling system is more efficient but if you want to use dynamic braking, you need to measure the frequency of the output of the generator, from this you can work out the RPM. Then set limits of how fast it has to rotate before the load resistors are connected. As it exceeds each limit, connect another resistor in parallel across the output, either using a relay or a MOSFET. I would suggest you leave one side of the resistors permanently connected and rather than select one from a range of values to connect to the other end, you gradually add more resistors in parallel. In other words, you don't disconnect one and connect another but just keep adding more in parallel. This reduces the need for such high power resistors and also makes the switching easier.

Brian.

 

[jiripolivka]

Dynamic braking as intended can work but in excessive wind speed your generator and load resistor can burn down due to overcurrent. A better idea is to set propeller to zero momentum by turning its wings to a loose angle. Small propellers allow the mounting pole to be mounted on a spring-loaded base, then the pole with the propeller bows under a high wind and no damage is done.

 

[Disha Karnataki]

u can use solid state switches where ever you want to have various different values of resistances. This solid state switches can be operated by giving commands either from uc or may be whatever circuit you design as u said that u want to give it a pulse when the speed reaches a particular speed by introducing a braking by putting a low resistance in the circuit.
so the cirucit what you can do is first of all you will have your motor then there will be 10ohm resistance in parallel with resistance of 0.101010ohm and it has in series solid state switch i.e,(10ohm||(0.10101ohm+solid state switch)). Now if you close the switch then you will have 0.1ohm in series once,if u open the switch then you will have 0.1 ohms in series with the motor.
i found out the resistance value as 0.1010ohm by parallel resistance formula
this should help
regards
disha