Controller circuit for Hilden Brandt motor needed..

[hartiberlin]

Great video.
well it shows how the permanent magnet flux is redirected into the
"U" type core that is attached behind the paper.
If no input power to the coil is applied,
all the flux goes the shortout way via the electromagnet?s
path core.
When power is applied, the flux is redirected into the outer U shaped core
and you can see, that the pull force is much more,due to
the flux of the magnet is added...

[LarryC]

Hi there Utilitarian,
Well yes and no.
With little power you can "redirect" the field of the magnet and it adds-to the electro magnet field, resulting in a bigger combined magnetic force. If it is not clear from the video. You can see that with the electro magnet only one can move the second core section around with not too much effort (not that much holding force). But once the magnets are added and the same electro magnet is engaged (with the same power) you now have the field of the electro magnet, as well as the field of the permanent magnet added together through the second core section. Giving it an greatly increased 'holding force' and as you can see in the video once the magnets are added to the electro magnet one can hardly move the secondary core section anymore. Beauty of it is that once the power is shut down. The field of the permanent magnet returns instantly to its position of least resistance, and thus it returns into the main core again, releasing its grip on the secondary core. So you can see this as a valve that 'valves' magnetism 1/2 of the total magnetism is from the electro magnet and the other half is supplied by the magnets. Main point of it all is that the magnets-on-the-core situation gives you much more holding force then the electro magnet alone (for the same power input).

Steven

Yes, and not just double. According to Maxwell's Pulling force formula of F = B squared A / (2 μ0). Where B is flux density, when you double the flux density, it is squared,  so that you now have 4 times the pulling force.

Regards, Larry

[dingbat]

Okay, dingbat,
but how much was it slowing it down ?

It made the motor quite useless.  It caused an effect that was like torque reversals as the coils discharged through the diodes.  I was initially surprised how the diodes killed the motor, but when I thought about it it made sense.  The diodes cause current in the coils that causes a magnetic pulse that happens to counteract the armature rotation at the instance it occurs.  I don't know if the motor would have kept running with the diodes in the circuit.  It seems that the spikes must be allowed to dissipate somewhat unchecked to not disturb the torque being produced.

If the voltage is allowed to rise, the current can remain low.  With little or no current flow when the coils discharge, there is no magnetic disturbance during the discharge, which allows the armature to advance past the magnet during the release portion of the cycle.  When the current flows through the diodes, the valve grabs the armature as it is trying to move away to the next pole.  The effect was very dramatic and devastating to the proper operation of the motor.

I might note that the operation of the motor was very impressive too.

I am sure that it is possible to add solid state switching that can withstand the voltages we were seeing from the coils.  Honk was almost there.  I think that if and when he has time he can make the controller work with the information he has on the back emf and the forward emf spikes we saw.

Honk,  Is there a simple way to take some high voltage IGBT's or something similar, and connect the points to directly fire the IGBTs - just to do a simple test on the motor?  I will be busy for the next several weeks, but I could possibly make a trip down late in June,  and hook up some temporary switching stuff to the existing points if you think it would work.  I am not an expert on high voltage switching transistors, so I don't know if they would survive the voltages we recorded during the testing.  If you could advise me on how to do something like this I could try to put something together for Jack and help him get it going.  I'm just thinking some heavy switching electronics bolted to a heat sink or something.

Of course this would only be done with Jacks consent.  It is his stuff, and I play by his rules.

db

[Honk]

Honk,  Is there a simple way to take some high voltage IGBT's or something similar, and connect the points to directly fire the IGBTs - just to do a simple test on the motor?  I will be busy for the next several weeks, but I could possibly make a trip down late in June,  and hook up some temporary switching stuff to the existing points if you think it would work.  I am not an expert on high voltage switching transistors, so I don't know if they would survive the voltages we recorded during the testing.  If you could advise me on how to do something like this I could try to put something together for Jack and help him get it going.  I'm just thinking some heavy switching electronics bolted to a heat sink or something.

Of course this would only be done with Jacks consent.  It is his stuff, and I play by his rules.

db

Hi dingbat.

You could use this Ixys IGBTI, type XEL40N400 that handles 4000V.
http://www.ixyspower.com/store/Family.aspx?i=19
I'm not sure wether you can get hold of some samples on this transistor in time for your visit.
But it is an american company, tho. It might help you if you have the right connections.

[Liberty]

@Dingbat and Jack,

If the motor coil voltage spike is allowed to rise and expire, the voltage will probably eventually break down the insulation on the coil wire.  I have a suggestion to consider.  Would a resistive wire (like a spark plug wire) and a spark plug (spark gap) allow the voltage to rise and opposing current to decrease, so that when the spark discharges in the spark plug, the impedance is at such a mismatch for the 6 ohm coil that it does not create much of a counter magnetic field to the motor when it is running, but still discharges the spike safely without damage to the coil???

Just a thought to toss around.

Good luck Jack and hope you continue to recover.