An open question about SG pulse motors

[ren]

Are your generator windings inductively coupled to your motor windings or are they on separate forms?

[tecknomancer]

inductively coupled

Are your generator windings inductively coupled to your motor windings or are they on separate forms?

the ac gen is not connected at all for now so it could be elemated from the equation, and no stray voltage is on the ac generator coils.

[smw1998a]

The output is going to a 44Ah 12 v telecom battery all of the collapse seems to be going to the output battery its hard to tell because it climbing when I'm checking the output but its about the same give or take an amp it's all heavy duty stuff I can only run it for a few min before I start freaking out out but nothing is even warm. possibly the generator? not sure on that it's not connected in any way to the circuit

maybe I found a way to dump back into the aether

thanks for you input

Hi Tecknomancer,
I will try and look at this from a different point of view. Your target speed is 1750RPM which equates to 233.3Hz. The time between passing rotor magnets TDC would be 4.2mS as the coils are triggered shortly after TDC a combined coil charge and discharge time of <2mS is required to maintain positive acceleration on the rotor.

Currently, you are achieving 700RPM which is a frequency of 93.3 Hz. The time between magnet passes is 10.7mS. To maintain positive acceleration on the rotor your coils must charge (to repel the rotor magnet) and discharge (to prevent repelling the next approaching rotor magnet) in TDC plus 5mS. I'm of the opinion that your motor is not charging and discharging the coils in the required time to maintain positive acceleration.

There may be several characteristics of the trigger circuit which are conspiring against you here. Since the inclusion of the SS magnet retainers and the inductive generator you now have your base resistance set to minimum. I assume this was to maintain positive acceleration and a single pulse per magnet pass. This alone will significantly increase the 'on' duration of the transistors (coil charge) and may also increase the coil discharge duration. Charge performance could remain largely unaffected as the extra input current is spent repelling the rotor magnet.

Another unavoidable fact is it takes current to repel a magnet, the more torque required, the more current necessary, even with a pulse motor. The duration of the rotor magnets interaction with the core of the coil can also significantly increase the coil charge duration. At 1750RPM the interaction can be as little as 0.8mS where as 700RPM the interaction can be 2.1mS. at 350RPM it is 4.2mS and as the charge time of the coil, with a given input voltage and base resistance, is much shorter than 4.2mS multi pulsing will occur.

It is clear that your recent additions are having a detrimental affect on the prime mover in your set up. My gut feeling suspects mechanical loading on the shaft is being exacerbated by some of the characteristics mentioned above. A simple test would be to replace your 12v charge battery with two 12v in series (24v) and see if you can attain higher RPM due to the shorter collapse, if so, place a third in series (36v) and see if RPM increases again.

Regards Lee..

[tecknomancer]

to maintain positive acceleration

Hi Tecknomancer,
I will try and look at this from a different point of view. Your target speed is 1750RPM which equates to 233.3Hz. The time between passing rotor magnets TDC would be 4.2mS as the coils are triggered shortly after TDC a combined coil charge and discharge time of <2mS is required to maintain positive acceleration on the rotor.

Currently, you are achieving 700RPM which is a frequency of 93.3 Hz. The time between magnet passes is 10.7mS. To maintain positive acceleration on the rotor your coils must charge (to repel the rotor magnet) and discharge (to prevent repelling the next approaching rotor magnet) in TDC plus 5mS. I'm of the opinion that your motor is not charging and discharging the coils in the required time to maintain positive acceleration.

There may be several characteristics of the trigger circuit which are conspiring against you here. Since the inclusion of the SS magnet retainers and the inductive generator you now have your base resistance set to minimum. I assume this was to maintain positive acceleration and a single pulse per magnet pass. This alone will significantly increase the 'on' duration of the transistors (coil charge) and may also increase the coil discharge duration. Charge performance could remain largely unaffected as the extra input current is spent repelling the rotor magnet.

Another unavoidable fact is it takes current to repel a magnet, the more torque required, the more current necessary, even with a pulse motor. The duration of the rotor magnets interaction with the core of the coil can also significantly increase the coil charge duration. At 1750RPM the interaction can be as little as 0.8mS where as 700RPM the interaction can be 2.1mS. at 350RPM it is 4.2mS and as the charge time of the coil, with a given input voltage and base resistance, is much shorter than 4.2mS multi pulsing will occur.

It is clear that your recent additions are having a detrimental affect on the prime mover in your set up. My gut feeling suspects mechanical loading on the shaft is being exacerbated by some of the characteristics mentioned above. A simple test would be to replace your 12v charge battery with two 12v in series (24v) and see if you can attain higher RPM due to the shorter collapse, if so, place a third in series (36v) and see if RPM increases again.

Regards Lee..

thanks lee I will be setting up some old wheels i have without the stainless steel covers to eliminate this as a issue, before the rebuild had reached 1800rpm with headroom to spare and I also before the rebuild mounted a generator on the back that was a real drag and the motor only went up a few amps here is a link to that video I will try to eliminate the various possible causes this week and post them here, also the amp draw does not seem constant with the loading of the motor at all , thank you for you input

[tecknomancer]

stainless steel covers 2

I had a wheel the same size in PVC plastic and I removed both wheels and put the one wheel on the trigger side it still went to 7 amps the rig with one wheel is vary sluggish so the stainless steel covers my be a factor but not the only one

[tecknomancer]

Problem Solved !!

1st thanks for everyone's input

The problem was something not found on most SG builds I have a 27ohm boost switch, that just makes it easy to start it's never on more than a min somehow in the rebuild I broke the switch and it was on inside so instead of 160 oms it was 27 ohms DUH and the trim pot was in parallel BUT it's fixed back down to able run on 500ma so now after the wheels rebalanced I can get back to testing at 120v dc I will post back on zeropointfuel.com and in the VMG project thread on this forum thanks agian

[tecknomancer]

stainless steel covers

they work fine so far

[smw1998a]

1st thanks for everyone's input

The problem was something not found on most SG builds I have a 27ohm boost switch, that just makes it easy to start it's never on more than a min somehow in the rebuild I broke the switch and it was on inside so instead of 160 oms it was 27 ohms DUH and the trim pot was in parallel BUT it's fixed back down to able run on 500ma so now after the wheels rebalanced I can get back to testing at 120v dc I will post back on zeropointfuel.com and in the VMG project thread on this forum thanks agian

That's good news Teck! Good luck with the testing.
Regards Lee.

[citfta]

Good news

Glad to hear the good news. Now I am looking forward to the test results.

I really like your design idea using a double shaft motor as a generator and bearing support at the same time. Good thinking. I may give that a try myself.

Carroll