wfouri
1 mW
So I have a few questions.
I have like so many people blown a motor or two, and can't afford buying expensive replacements.
A little background, I built an electric trials motorcycle, using an old "fantic key roo" frame, bit heavy but strong. Threw in an 25kw outrunner motor. Definitely doesn't produce torque. Paired it to a kelly kls-d motor controller, capable of 200A constant. Running 48v 44ah lithium cobalt batteries, high discharge rate, can do 500A. This motorcycle was ment to produce torque and used for just silly things.
The motor didn't make it through the testing phase, I was still running current around the 100A mark and it just smoked the motor.
So now I am considering joining the crowd in converting an old alternator, theoretically it's possible. I am however unsure of how effective it would be or how long it will last. The windings on a normal Automotive alternator are rather thick and you can find once rated above 100A of the older types.
So basically you strip the Alternator and turn it into an hybrid induction motor. You remove the rectifier and connect the phase (stator) wires to your standard controller, the rotor or field wires you want to connect to a DC speed controller to be able to vary the current going through the field, more current means more torque, but less speed and high losses, you just need it to start the motor and get low down torque. Since alternators usually work on demand, meaning that the regulator usually varies the field depending on the charge rate required to charge a battery and run all the lights ex.
So the hard part is how does one vary the field?? An idea I am toying with is just to take the potentiometer from the DC speed controller and building it into the twist grip, but its less than ideal, and you require a second pot inline to be able to tune the motor to be at its sweet spot at full throttle. Another option could be some sort of sensor on the rear wheel, to reduce the field as the wheel speeds up. Can a pas sensor be used for this? Does anyone have an idea of how that would be connected?
Controlling the stator is the easy part, just fit hall sensors to the motor, and connect the wires as per usual. It's controlling the field that seems to cause some difficulty.
Would like to hear some opinions and advice.
I have like so many people blown a motor or two, and can't afford buying expensive replacements.
A little background, I built an electric trials motorcycle, using an old "fantic key roo" frame, bit heavy but strong. Threw in an 25kw outrunner motor. Definitely doesn't produce torque. Paired it to a kelly kls-d motor controller, capable of 200A constant. Running 48v 44ah lithium cobalt batteries, high discharge rate, can do 500A. This motorcycle was ment to produce torque and used for just silly things.
The motor didn't make it through the testing phase, I was still running current around the 100A mark and it just smoked the motor.
So now I am considering joining the crowd in converting an old alternator, theoretically it's possible. I am however unsure of how effective it would be or how long it will last. The windings on a normal Automotive alternator are rather thick and you can find once rated above 100A of the older types.
So basically you strip the Alternator and turn it into an hybrid induction motor. You remove the rectifier and connect the phase (stator) wires to your standard controller, the rotor or field wires you want to connect to a DC speed controller to be able to vary the current going through the field, more current means more torque, but less speed and high losses, you just need it to start the motor and get low down torque. Since alternators usually work on demand, meaning that the regulator usually varies the field depending on the charge rate required to charge a battery and run all the lights ex.
So the hard part is how does one vary the field?? An idea I am toying with is just to take the potentiometer from the DC speed controller and building it into the twist grip, but its less than ideal, and you require a second pot inline to be able to tune the motor to be at its sweet spot at full throttle. Another option could be some sort of sensor on the rear wheel, to reduce the field as the wheel speeds up. Can a pas sensor be used for this? Does anyone have an idea of how that would be connected?
Controlling the stator is the easy part, just fit hall sensors to the motor, and connect the wires as per usual. It's controlling the field that seems to cause some difficulty.
Would like to hear some opinions and advice.