Using PM motor as motor and generator at same time?

[rhubarb]

I'm a novice at electronics, and I've got a question pertaining to a project I've got going. I'm wondering if it is possible to set up a permanent magnet motor to work as both a generator and a motor at the same time. Well not exactly at the same time, but rather switching immediately back and forth. I would also need the motor control to have a throttle/speed control.

Any help on this is appreciated. I don't mind doing my homework, if anyone can help me get started in the right direction. Thanks,

rhubarb

 

[Resqueline]

A PM motor will start to work as a generator all by itself when its shaft speed is taken above its theoretical free-spin (no-load) speed.
Some PWM motor controller configurations seems to take care of "regenerative braking" as it's also called.