Interesting data on how to get an induction motor that has been converted to an Induction generator started to generate power.
Offered by Mike.
- The loss of magnetism that his motor shows is classical and it is the true reason why the motor as a generator has to be started or turned off with the loads removed. Two hints that I have tried and seem to work.
- Use a large amount of capacitance to get the generator to start and then switch out the extra capacitance (Leaving only the capacitance that is necessary to keep the generator going) once the generator is up to speed. Most motors have centrifical switches within them to do just that to the starting capacitor, when used as a motor.
- Putting a permanent magnet as near as possible to the windings. I think this works by causing a magnetic field to exist near the windings, then when the rotor disturbs the magnetic field, this induces voltage within the windings and the generator then takes off on its own. I've done this on one of my induction generators and it seems to help.
- Actually, if the induction motor come generator is connected to the power grid, no mods at all to the motor are required (the grid serves a similar function to the capacitors). If no wind is blowing or if the "generator" is turning slower than its synchronous rate however, it will act as a motor (not suprisingly). A switch is therefore required to disconnect the motor/gen until the wind is strong enough to spin it above the sync speed. One nice thing is that the system is self-synchronizing i.e. the gen automatically produces power at the same frequency and in sync with the power grid.