Tinman's Rotary Transformer

[scratchrobot]

I tried running an old washing machine motor from a 12v lipo battery and was amazed it ran so well.
http://www.youtube.com/watch?v=tPF7s9r8K7A
http://www.youtube.com/watch?v=S9latuhlCMo

[tinman]

Actually, it would be 50 pulses per sec.

Mags

Mags
50Hz is 50 complete cycle's per second,that means 100 half cycles per second.When we rectify the ac,we bring the bottom half of the wave,and place it between the two top half's. This give's you 100 half wave cycles,or 100 pulses a second.

[tinman]

@ Tim
You must also remember the overlap on the rotor segments to that of the brushes.This means that four rotor segments have current passing through them at once, 80% of the time.
As you will see in the video's,my motor only runs at around 1200 to 1300 RPM.
Dont forget that in the video of the scope trace i am using a PWM at high frequency,and also notice the half wave AC. But you will also see no switching of the rotor segments in the scope,and this is because the current flow is never broken-due to the over lap.
So we have a situation were we have 2 rotor segments on,then 4, then 2 ,then 4 -and so on.
This also means that your math is not a constant,and only true for 20% per revolution.

Please dont get me wrong here. What you explained is very true and correct,but there is more happening.When you get yours up and running,do a test between pulsed DC or rectified AC,and straight DC.Work out P/in for both,torque out for both,and also P/out for both. You will find that the pulsed P/in is far more efficient.
In reguards to the overlap of the brushes to rotor segment's,you will find that the rotor segment aproaching the stator core,is always on-this is how they work in normal operation.So if it's always on,how dose the field around the stator core collap's?]
Now like you said,the frequency of the rectified ac is very low,and it is this that makes this unit very average in performance. The frequency would need to be matched to each rotor segment,and then we would have something realy cool. But us poor men have to use what we have lol.

Anyway,i am going to dust of the old unit,and reserch it right along side you on this thread.Now i have my two channel scope,we can look at the current in,and p/out from the stator coils. This way you will be able to see exactly what is happening.
As you said-this motor realy isnt good for this effect to work. But in saying that,even this motor far outperforms an off the shelf motor.
Oh,and there is one other hickup we have to sort out,and that comes when you try to use two stator coil's. I havnt figured that one out yet,but i think we will have to cut the stator housing in half???.

[Liberty]

@ Tim
You must also remember the overlap on the rotor segments to that of the brushes.This means that four rotor segments have current passing through them at once, 80% of the time.
As you will see in the video's,my motor only runs at around 1200 to 1300 RPM.
Dont forget that in the video of the scope trace i am using a PWM at high frequency,and also notice the half wave AC. But you will also see no switching of the rotor segments in the scope,and this is because the current flow is never broken-due to the over lap.
So we have a situation were we have 2 rotor segments on,then 4, then 2 ,then 4 -and so on.
This also means that your math is not a constant,and only true for 20% per revolution.

Please dont get me wrong here. What you explained is very true and correct,but there is more happening.When you get yours up and running,do a test between pulsed DC or rectified AC,and straight DC.Work out P/in for both,torque out for both,and also P/out for both. You will find that the pulsed P/in is far more efficient.
In reguards to the overlap of the brushes to rotor segment's,you will find that the rotor segment aproaching the stator core,is always on-this is how they work in normal operation.So if it's always on,how dose the field around the stator core collap's?]
Now like you said,the frequency of the rectified ac is very low,and it is this that makes this unit very average in performance. The frequency would need to be matched to each rotor segment,and then we would have something realy cool. But us poor men have to use what we have lol.

Anyway,i am going to dust of the old unit,and reserch it right along side you on this thread.Now i have my two channel scope,we can look at the current in,and p/out from the stator coils. This way you will be able to see exactly what is happening.
As you said-this motor realy isnt good for this effect to work. But in saying that,even this motor far outperforms an off the shelf motor.
Oh,and there is one other hickup we have to sort out,and that comes when you try to use two stator coil's. I havnt figured that one out yet,but i think we will have to cut the stator housing in half???.

Hi Tinman,

Just curious, what are the best figures have you been able to obtain for overall efficiency of the motor in your configuration?

Liberty

[gotoluc]

i am going to dust of the old unit,and reserch it right along side you on this thread.Now i have my two channel scope,we can look at the current in,and p/out from the stator coils. This way you will be able to see exactly what is happening.

Thanks TM for bringing this project back out.

I'll be watching the tests with interest

Luc