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Running switching and acceleration sensor

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Evgenij

Thu Mar 13 2008, 10:52AM

Registered Member #200 Joined: Sat Feb 18 2006, 01:49AM
Location: Pskov, Russia
Posts: 21

I work above the new accelerator. Probably, that my technical
decisions will be interesting to you. I offer three ideas which can improve the accelerator.
1. Running switching of SCR-keys from sensor coils.
2. Two capacitors bank with transition of energy of an induction from one bank to another.
3. The only one sensor (of acceleration) instead of many optic sensor of each coil.

The preliminary information is accessible in Russian only here: link moved to modern launcher

I assume, that you can use service of language translations,
for example Google language translator, to read from Russian text for pre-translation. It will not be very clear, but pictures should help for more understanding.
I ask someone of members of HV Community Forum to translate from the general sense to clear English language and to place here the explanatories with circuit's pictures from my Russian forum. So all the interested people can familiarize with new decisions.

Dr. Shark

Fri Apr 11 2008, 01:15PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

For some reason the page is messed up by the google translation

but I think I get what you are doing anyway. In fact I had the same idea a while ago, but did not get round to experimenting with it. The idea (or at least my take) relates to the diagonal half-bridge which two SCRs and two diodes that can be used to recover energy from the coil back to the capacitor bank. The same can be done with just _one_ SCR and diode, if there is a second capacitor bank that takes the reverse current with the opposite polarity. Basically this amounts to creating a bipolar capacitor from two electrolytics by connecting them in anti-parallel with a diode / SCR in series with each.

Evgenij

Wed Apr 16 2008, 11:38PM

Registered Member #200 Joined: Sat Feb 18 2006, 01:49AM
Location: Pskov, Russia
Posts: 21

Yes, this scheme like diagonal half-bridge work.
But it has some advantages:
1. Both transistors cope concerning the general wire (low-side directly).
2. SCR's are switched from coil's EMF serially automatically after switching of transistors.
3. One general sensor of acceleration instead of individual optical position sensors for each stage is used only.

The multistage accelerator with running switching solenoids
(The application for the invention is submitted on October, 5th 2006Ð³.)

The primary goal of the offered decision is construction of the effective accelerator with a lot of the steps, providing partial Ñ€ÐµÐºÑƒÐ¿ÐµÑ€Ð°Ñ†Ð¸ÑŽ energy of a self-induction at the strong magnetic fields, allowing to place solenoids on a trunk without intervals between the steps, having high reliability and noise immunity at a simple compact design and small quantity of power electric wires.

In figure the scheme of connection of the basic parts of the accelerator with two serially included groups of solenoids is shown.

By figures on the scheme are designated:
1 â€“ a ferromagnetic shell;
2 â€“ a trunk;
3 - the traction solenoid with the basic force coil;
4 - an additional touch winding of the traction solenoid;
5 - SCR's key;
6 â€“ power wires;
7 - the operating device;
8 - a transistor group key;
9 â€“ switching wires;
10 - energy recuperation circuit;
11 - a condenser energy source.

The multistage electromagnetic accelerator with the sensor of acceleration
(The application for the invention is submitted on December, 14th 2006Ð³.)

In figure the scheme of connection of the basic parts of the accelerator is shown.
By figures on the scheme are designated:
1 â€“ a ferromagnetic shell;
2 â€“ a trunk;
3 - the traction solenoid;
4 - the operating device;
5 â€“ the sensor of linear acceleration of a trunk;
6 â€“ means of serial switching of windings of solenoids;
7 - a condenser energy source.

Both invention combined in one device for most effectivity (running switching and acceleration sensor).

Dr. Shark

Thu Apr 17 2008, 11:35AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Evgenij, good to hear from you again!
I am not entirely sure I understand your second concept with the acceleration sensor, but the first one sounds very interesting to me. In fact it is a bit similar to what Thomas did here

(great, now we have Russian AND German here!), he also has an additional trigger winding on each coil. It is still a bit different though since he is using spark gaps and not SCRs.

Do you have a coilgun prototype that uses this principle? I'd be interested how well it is working, maybe I can use it in my coilgun so I don't have to mess with optical triggers and all the associated logic.

TheMerovingian

Thu Apr 17 2008, 01:26PM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

I tried a similar Hybrid design using IGBTs+SCRs but it failed because the SCRs turn off slowly, giving problems of stages turning back-on in multistage designs

Evgenij

Thu Apr 17 2008, 07:41PM

Registered Member #200 Joined: Sat Feb 18 2006, 01:49AM
Location: Pskov, Russia
Posts: 21

Problems:
1. SCRâ€™s are closed slowly. It is the truth. The resistor in a roundabout circuit accelerates recession of a current. But it is necessary to pay for it a high overvoltage of transistors and SCRs. But speed is fast in last stages and SCRs does not suffice time for turn-off.

Then I began to use not two phases, and three. Three transistors switch three groups. One transistor is turned to on. The second is switched off, but the current in group continues to go and decreases. The third transistor is switched off, the current does not go and SCR has time to be switched off. So I use three transistors, three capacitors, three groups of SCRâ€™s keys. After deenergizing the current comes back to capacitors on a circle 1-2-3-1.

2. The sensor measures acceleration of a barrel (acceleration of kickback force). The sensor should be fast. On-chip MEMS-accelerometer with 10 kHz bandwidth have not time to see acceleration from each stage. The sensor should see the contribution of each step to acceleration of a barrel. When the bullet precisely in the center of coil, acceleration is zero. This signal can be received from the fast sensor, but it is late a little. Even if to look at a maximum of acceleration of each stage is there will be a moment when already late to switch off a transistor. It is necessary hardly earlier.
The decision - to supervise simultaneously a current through the transistor and acceleration. Acceleration depends on a position of a bullet (force depends on position). And the current too varies.
Then also a signal of acceleration we subtract a signal of a current and there is only an acceleration from a position. The result is similar to known diagrams where dependence of force on position of a bullet is shown at a direct current in the coil. Now during the moment of a maximum of acceleration it is possible to switch the next step.
The offered decisions are not completely checked up yet. While it only food for mind.

More completed circuit shown

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