Sharing ideas on how to make a more efficent motor using Flyback (MODERATED)

[verpies]

How much control do you want to have over the pulses going to the motor?

That is a very good question because many home-made rotors often are not made symmetrically, and e.g. a 8-magnet rotor might not have the magnets spaced exactly 45º apart or the magnets are not magnetized evenly, requiring the stator pulses to be precisely tailored to the magnet positions.

There are some 3 phase motor controllers already built that are pretty cheap.  They are used in Radio Control vehicles. 

What shaft position sensor do they use?
Do they allow the energizing pulse to be positioned at specific shaft angles ?  How about the "flyback" pulse ?

[citfta]

That is a very good question because many home-made rotors often are not made symmetrically, and e.g. a 8-magnet rotor might not have the magnets spaced exactly 45º apart or the magnets are not magnetized evenly, requiring the stator pulses to be precisely tailored to the magnet positions.
What shaft position sensor do they use?
Do they allow the energizing pulse to be positioned at specific shaft angles ?  How about the "flyback" pulse ?

It looks like tishatang has done more research on these controllers than I have so he could probably answer your questions better than I.  I was under the impression the controller sensed the signal coming back just as tishatang has said.  There are no other position sensors on the little motors.  They only have the 3 phase wires going to them.  I do know there is a lot of information available on the RC forums about the controllers and rewinding the motors and so forth.  If luc thinks these can be used I would be glad to do more research to see how they could be used.

Tishatang I would like to see the simple $5 control circuit you mentioned.  I might have a good use for that sometime and not have to connect up the transmitter and receiver just to control a motor.

Carroll

[tishatang]

Quote by Verpies
_{"That is a very good question because many home-made rotors often are not made symmetrically, and e.g. a 8-magnet rotor might not have the magnets spaced exactly 45º apart or the magnets are not magnetized evenly, requiring the stator pulses to be precisely tailored to the magnet positions."}

I just realized, the test motor has 8 poles and the stator has 12 poles.  The idea of an ESC will not work because of the timing issue based on non-sensored motors.  They measure the back emf of the non-energized pole.  This gives close enough timing to work.  Maybe an ESC will work if a position sensor is added?  Some ESC can handle both types of sensing.  In this case make sure the ESC is for motor with sensor.

I am fairly certain the DC motor/alternator system will work because the rotor, regardless the number of poles, will try to follow the rotating magnetic field within the stator.  I would guess there will be speeds that will lock on at specific rpm's that are in sync with multiples of 8 and 12?  Harmonic steps that will be more efficient and stable?

Chris

[tishatang]

@Carroll

Here is a link to different kinds.  They are called servo testers.  They are used on the bench to check the flaps and speed of motor without the use of radio.  First, I used the cheap light blue one.  Then I went to the big red knob one.  Has finer control, better pot.

http://www.hobbyking.com/hobbyking/store/__470__189__Servos_Parts-Servo_Tester.html

Chris

[citfta]

I feel like a total dunce!  I have a servo tester.  I just never thought about using it for controlling the esc!!

Thanks Chris!!

Carroll