top266eg to slow to recovery (90V 1A)

What is the application? Are you trying to ramp up the current in your electromagnet, reduce it, then ramp it up again? The ramp time may be limited by the inductance of the electromagnet and the voltage available. What is its inductance and resistance?

hello i am come back 

The application is Stud welding using the specific gun.Inside the gun ther is a solenoid.

to activate the solenoid i need the 90 volt 1 amps. to aid the system ther is connected one capacitor external at the pc board of 4700 uf 100V.

When i start to weld this solenoid must be active for 100ms maximun 300 ms.

if i try to use this circuit the first time is ok but after weld , the voltage rise up to 40/50 volt in 5/10 seconds and don't increase never over this value.

sometime the value of voltage return to 0 volt.

the inductance of solenoid is 40 mH  and 18 ohm resistance.

what do you think about?

i 'm forget:

i not used the core material 3F3 like project , but N87 with gapped core of 0,20 mm.

A solenoid with 40mH inductance and 16 ohms resistance will have an L/R time constant of 2.2 ms. This means that the current will rapidly ramp up to 90/18 amperes  in a time much shorter than the 100 ms time you need for solenoid activation. This also means that the power supply must be capable of sourcing 90/18, or 5 amperes to keep the solenoid activated for the time you need. I think you will need a solenoid with higher inductance and resistance to work with the power supply you have, as it would not be really practical to have a 450W power supply in place just for activating your solenoid..

i not need that the voltage stay 90 v constant but when the solenoid is energized after ,the voltage can fall down up to 65 volt.in this situation the mechanism of solenoid stay locked correctly.

so i need a little current to energized the solenoid.how to modific the circuit to obtain this result?

thanks

If you allow the power supply voltage to fall to 65V during  the course of the100 ms on period, the current through the solenoid will still be 65/18, or 3.6A. This is over twice the nominal power rating of your current power supply (235 W vs. 90 W), and will likely trigger primary overcurrent protection, which is the problem you were seeing originally.  You  need either a different solenoid design or a power supply design that can deliver 235 W for 100ms without going into protective shutdown. Since the primary overcurrent shutdown protection is pretty much instantaneous compared to the required 100 ms  on period, the power supply will need to be sized to deliver 235 W.

ok , i understood.i try to consider a new design.

thanks

I have reviewed the characteristics of my solenoid.

considering that the power supply correctly delivers the voltage of 90 volts and 1 ampere, however, I have a problem.

when I turn it on it takes about 15 seconds to get to the nominal voltage of 90 volts.

moreover when I connect the load (it absorbs about 1.1 amps) it goes into protection and takes a long time to get back to working properly.

I point out that I am using ferrites type n87 eno 3f3 as per project.

best regards

OK, I actually sat down and did an analysis of the design using PIXLS - first, the TOPSwitch in the current design is too small to deliver the required output power. Second, the clamp zener is only 100V, while your output reflected voltage is >130V. This means that a lot of the power stored in the transformer will go to heating up the clamp zener instead of being transferred to the output where it belongs. The clamp zener should be an 180V diode rather than a 100V diode. I have attached a PDF of a sample spreadsheet that has a design which should work for you if implemented properly. All the caveats I have mentioned regarding the load imposed by the solenoid still apply.

just possible, i try to modify the original project.

thanks

have a nice day

hi

I tried to build the circuit with the values you recommended in the pixls sheet.

I kept the basic scheme I posted, looking at your prescriptions.

the power supply tries to start and at the output on the secondary I get a maximum of tens of volts.

I state that the transformer I wound has 2x 17 turns on the primary with a 0.5 mm diameter wire and the secondary 24 turns with a 0.5 mm diameter wire. the bias has 4 turns with a 2x 0.45 mm wire

the ferrite I'm using is type n87.

the gap between one ferrite and the other is 0.5 mm.

I do not know what to do.

I would need a schematic that works with a maximum peak of 1.5 amps always using an ETD29 and series top switch.

i hope you have a solution for me.

if you need more information on the circuit I built, feel free to ask me.

the link of my design is: https://piexpertonline.power.com/piexpert/design/select?share=1a1eeb17be685aee593bc16ca0d839b7045663311406b014e6b3e03aebaeb375

I thank you in advance.

Are you still trying to drive the same solenoid you referenced earlier?

If you are trying to drive the same 18 ohm solenoid with  your power supply, it will not work, as the low solenoid resistance draws enough current to trigger the primary overcurrent protection of the TOPSwitch. I explained this earlier on in this thread.

You will need a 90 ohm solenoid, or a power supply capable of delivering at least 235W to work with the 18 ohm solenoid. In order for the 235W supply to work with the 18 ohm solenoid, you will need to add some circuitry to the secondary to approximate a constant power characteristic that allows the output voltage to droop and the output current limit to increase without triggering primary overcurrent protection.

The comments I made earlier regarding the power supply characteristics were addressing its capability solely as a 90W power supply and did not address the compatibility with the 18 ohm solenoid. 

hello

yes, i drive the same solenoid.

what  type of circutry need to add?

the last project that you have advise me don't work.

i have followed fine your data but......nothing.

I told you very early on about the power required to drive the 18 ohm inductor, and that it wouldn't work with a 90W supply. You will need at the minimum a 235W supply (as I explained earlier) to  power the 18 ohm inductor. - this is by allowing the output of the supply to sag to 65 VDC, otherwise the power requirement would be even higher.. I noticed that your current design was for 190-265VAC is this your present input requirement, or will you need to run full range? If you need to run full range, you will need to run a switchable doubler for the low range. in order to get the power you need using a TOPSwitch. 

Here is an add-on circuit that changes the output characteristic of your 90V, 90W power supply to a decent approximation of a constant power characteristic, which means that when the current limit is reached, the output voltage drops, but at the same time, the output current limit  increases, all without triggering the primary overcurrent protection, as the output current is controlled.

For your 90V, 90W supply, the current limit will be around 1A. With the 18 ohm solenoid load, the output voltage will fall to ~40VDC, while the output current limit will increase to ~2.2A . This may not be sufficient power to properly hold the solenoid in place for your purposes, but at least the power supply will not go into protection mode, which is currently the problem you are experiencing.

To run this circuit, you will need a separate secondary-referred safety isolated 25V bias winding, which can be implemented using fine gauge triple insulated wire with flying leads for proper safety spacing. The bias winding voltage will drop from 25V to ~11V when loaded by the solenoid, but this is still sufficient to properly run the constant-power circuit. This bias winding is in addition to the primary-referred bias winding used to power the TOPSwitch.  For initial evaluation, you could power the add-on circuit using a pair of 9V batteries in series pending modification of your transformer

With the constant power circuit in place, you will at least be able to drive the 18 ohm solenoid load without entering overcurrent protection mode. If the 90W power is insufficient for proper holding force, we can talk about options for increasing the supply output power and the mods needed for the constant power circuit.

I strongly suspect this power supply is meant  to replace an impedance-controlled transformer that would supply the necessary power to run the solenoid with the only limitation being thermal/duty cycle considerations.